1. |
- Droog Tesselaar, Erik, et al.
(författare)
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Nonspecific vasodilatation during transdermal iontophoresis : the effect of voltage over the skin
- 2003
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Ingår i: Microvascular research. - 0026-2862. ; 65:3, s. 172-178
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Tidskriftsartikel (refereegranskat)abstract
- We used laser Doppler perfusion imaging (LDPI) to study nonspecific vasodilatation during iontophoresis. In iontophoresis studies, nonspecific vasodilatation occurs as a result either of galvanic currents or of the applied voltage over the skin. We made dose–response measurements to study the effect of ionic strength of the vehicle on the nonspecific vasodilatation during iontophoresis of sodium chloride and deionized water, while we monitored the voltage over the skin. We found that anodal and cathodal ionotophoresis induced a voltage over the skin that was dependent on the ionic strength of the test solution. The nonspecific vasodilatation during anodal iontophoresis was less pronounced than during cathodal iontophoresis, and was independent of the voltage over the skin. The nonspecific vasodilatation in cathodal iontophoresis was related to the voltage over the skin, and was possibly mediated by depolarization of local sensory nerves. In experiments using cathodal iontophoresis, therefore, the ionic strengths of the vehicle and the drug are important when vasoactive drugs are examined, as the nonspecific vasodilatation needs to be controlled for. As the vasodilatation that we observed was heterogeneously distributed within the area of iontophoresis, LDPI may provide more accurate measurements than conventional laser Doppler perfusion monitoring.
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2. |
- Ajan, Aida, et al.
(författare)
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Reproducibility of Laser Doppler Flowmetry in gingival microcirculation. A study on six different protocols
- 2024
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Laser Doppler Flowmetry (LDF) is a non-invasive technique for the assessment of tissue blood flow, but increased reproducibility would facilitate longitudinal studies. The aim of the study was to assess the interday reproducibility of Laser Doppler Flowmetry (LDF) at rest, at elevated local temperatures, and with the use of the vasodilator Methyl Nicotinate (MN) in six interconnected protocols for the measurement of the blood supply to the microvascular bed of the gingiva. Methods: Ten healthy volunteers were included. Interweek LDF measurements with custom-made acrylic splints were performed. Six protocols were applied in separate regions of interest (ROI): 1; basal LDF, 2; LDF with thermoprobe 42 degrees C, 3; LDF with thermoprobe 45 degrees C, 4; LDF with thermoprobe 42 degrees C and MN, 5; LDF with thermoprobe 45 C and MN and 6; LDF with MN. Results: Intra-individual reproducibility was assessed by the within -subject coefficient of variation (wCV) and the intraclass correlation coefficient (ICC). Basal LDF measurements demonstrated high reproducibility with wCV 11.1 in 2 min and 10.3 in 5 min. ICC was 0.9 and 0.92. wCV after heat and MN was 4.9-10.3 and ICC 0.82-0.93. The topically applied MN yielded increased blood flow. Conclusion: This is the first study evaluating the reproducibility of basal LDF compared to single or multiple vasodilatory stimuli in gingiva. Multiple collector fibers probe and stabilizing acrylic splints are recommended. Vasodilatory stimulation showed a tendency toward higher reproducibility. Furthermore, MN yields vasodilation in gingiva.
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3. |
- Arildsson, Mikael, 1967-, et al.
(författare)
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Effects on skin blood flow by provocation during local analgesia
- 2000
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 59:1, s. 122-130
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Tidskriftsartikel (refereegranskat)abstract
- Although topical analgesia cream has been used for several years, little is known about its effects on the microcirculation. Previous studies have shown a vasoconstrictive effect after short application times and a vasodilatation after longer application. It has also been shown that vasomotion does not occur in the analgesized skin. The present study was undertaken to investigate the alterations in skin blood perfusion following local cooling, local heating and pin-pricking after the establishment of analgesia. In 11 healthy volunteers, skin analgesia was attained by use of a eutectic mixture of lidocaine and prilocaine (EMLA, Astra Pain Control AB, Sweden) applied to the skin three hours prior to provocation. The changes in skin blood perfusion, after applying three different provocation methods, were studied using the laser Doppler technique. Local cooling and heating to temperatures of +10 and +45°C, respectively, were applied for 9 s by use of a copper probe (Ø12 mm). In the pin-prick provocation method, a combined effect of deflection and penetration of the skin to in total 3 mm was attained. Identical provocation methods were applied to placebo treated and untreated skin areas. After heat provocation, significant differences in the perfusion response between the treatments were seen (P < 0.0001). Skin areas treated with analgesia cream responded with a slow increase in perfusion that persisted beyond the four minute measurement period. Placebo and untreated areas decreased their perfusion over time. After cooling a significant reduction in skin perfusion was seen, irrespective of the treatment. Similarly, after pin-pricking a perfusion increase was seen for all treatments. The findings indicate that topical analgesia influences the myogenic control of the blood flow in those vascular plexa measured by laser Doppler following heat provocation. No differences could be seen in the response to pin-pricking and cooling for the different treatments.
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4. |
- Arildsson, Mikael, 1967-, et al.
(författare)
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Skin capillary appearance and skin microvascular perfusion due to topical application of analgesia cream
- 2000
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 59:1, s. 14-23
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Tidskriftsartikel (refereegranskat)abstract
- Local topical analgesia changes basal skin perfusion and its regulation. In particular, the response induced by local heating, which in nontreated skin comprises a rapidly increased perfusion followed by a normalization within 30 s, is altered to a delayed and persistent perfusion increase. The response dependency to the analgesia cream application time, that is, the intradermal penetration of the analgesics and in which vascular plexa the response occurs, is not known. The aim of this study was to assess changes in the appearance of superficial skin capillaries and skin microvascular perfusion changes due to different application periods of topical analgesia cream (EMLA). Twelve subjects were treated with EMLA and placebo applied to the volar side of each forearm, respectively. The treatment areas were assigned different application times (20 min, 40 min, 1 h, 2 h, and 3 h). The areas were cleared from the creams and shortly thereafter provoked during 9 s with a probe heated to 45°C. To assess capillary number density and skin perfusion, capillary microscopy, and Laser Doppler perfusion imaging (LDPI), respectively, were used. The number density of physiologically active capillary was significantly decreased with longer application times of EMLA (P < 0.005). The LDPI-signal showed a persistent perfusion increase after provocation associated with increasing application time of the cream. This perfusion pattern was not seen after 20 min of treatment, but was present in 9 of 12 subjects after 3 h of treatment. No significant relationship between changes in the capillary number density and the LDF measurement was found. In conclusion, a longer application time and therefore a higher intradermal concentration and a deeper penetration of the analgesics was associated with a delayed and persistent perfusion increase after local heating. There was a discrepancy between changes in capillary number density and skin perfusion, indicating that the perfusion increase does not occur in the capillaries but in the deeper lying vessels. Hence, the contribution of the capillary perfusion to the LDF-signal is smaller than previously anticipated. Capillary number density and presumably their perfusion were decreased with longer application times.
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5. |
- Awan, Z A, et al.
(författare)
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Diffuse reflectance spectroscopy: Systemic and microvascular oxygen saturation is linearly correlated and hypoxia leads to increased spatial heterogeneity of microvascular saturation
- 2011
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Ingår i: MICROVASCULAR RESEARCH. - : Elsevier Science B.V., Amsterdam. - 0026-2862. ; 81:3, s. 245-251
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Tidskriftsartikel (refereegranskat)abstract
- The microvascular oxygen saturation (SmvO(2)) in the skin and tongue (sublingual mucosa) in pigs (n = 6) was characterised using diffuse reflectance spectroscopy (DRS). The correlation between arterial oxygen saturation (SaO(2)) and SmvO(2) as well as the spatial heterogeneity of SmvO(2) was examined during hypoxia. DRS uses shallow-penetrating visible light to assess microvascular oxygen saturation (SmvO(2)) in superficial tissue. Hypoxia was induced by gradual reduction in ventilation or reduction of the inspiratory oxygen fraction. The spatial heterogeneity of SmvO(2) was expressed as the coefficient of variation (CV) of repeated SmvO(2) measurements. Baseline SmvO(2) before interventions was 20.2% (10.3%-38.1%, median with range) in groin skin, 32.9% (13.0%-49.3%) in the ear and 42.2% (32.1%-51.5%) in the tongue. SmvO(2) in the groin was significantly lower than venous oxygen saturation (SvO(2)) (p andlt; 0.05) and SmvO(2) in the tongue (p = 0.03). There was a significant linear correlation between SaO(2) and SmvO(2) in all measuring sites for both interventions (pandlt;0.05). Similarly there was a significant correlation between CV of repeated SmvO(2) measurements and SmvO(2) in all measuring sites for both interventions (p andlt; 0.01). The results from baseline measurements indicate a surprisingly high oxygen extraction in the measurement volume of DRS, especially in the groin skin. A reduction of SmvO(2) with decreasing SaO(2) was found and additionally the results suggest that spatial heterogeneity of microvascular oxygen saturation increases during hypoxia. Microvascular disturbances have been demonstrated in both local vascular diseases and systemic conditions such as shock and sepsis, an assessment of microvascular oxygen saturation using DRS may be useful in the monitoring of the microcirculation in such patients. This study is a part of an ongoing characterization of the DRS technique.
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6. |
- Bansch, Peter, et al.
(författare)
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Effect of charge on microvascular permeability in early experimental sepsis in the rat.
- 2011
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 82, s. 339-345
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Tidskriftsartikel (refereegranskat)abstract
- A key feature of sepsis is hypovolemia due to increased microvascular permeability. It has been suggested that the negative charge of albumin and of the endothelial glycocalyx is important for maintenance of the normally low permeability for albumin. Here we tested the hypothesis that charge effects contribute to the increased permeability in sepsis. Transcapillary escape rate (TER) and initial distribution volume for (125)I-labeled bovine serum albumin (BSA, isoelectric point pH 4.6) and for (131)I-labeled charge modified BSA (cBSA, average isoelectric point, pH 7.1) was measured 3h after sepsis was induced by cecal ligation and incision (CLI) (n=11) and in control animals (n=12). The importance of charge for permeability in sepsis was estimated by comparing the ratio between TER for cBSA and TER for BSA during control conditions to that after CLI. Plasma concentration of the glycocalyx component glycosaminoglycans (GAGs) was measured in separate control and CLI animals. The initial distribution volume for BSA and cBSA in control animals was 38±3ml/kg and 47±4mL/kg and decreased by 17% and 19%, respectively, following CLI. TER for BSA increased from 16.7±4.1% in the controls to 20.1±1.9% following CLI. Corresponding values for cBSA were 26.7±5.6% and 29.8±3.5%, respectively. The ratio between TER for cBSA and TER for BSA was 1.62±0.1 in the control group and 1.49±0.1 following CLI (p<0.05). Plasma GAG concentrations were higher in CLI animals than in the control group. We conclude that CLI induce hypovolemia secondary to increased microvascular permeability. Negative charge contributes to the normally low permeability of albumin and the importance of charge is decreased in early experimental sepsis. The observed charge effects are associated with CLI-induced breakdown of the glycocalyx.
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7. |
- Barbu, Andreea, et al.
(författare)
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The use of hydrogen gas clearance for blood flow measurements in single endogenous and transplanted pancreatic islets
- 2015
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 97, s. 124-129
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Tidskriftsartikel (refereegranskat)abstract
- The blood perfusion of pancreatic islets is regulated independently from that of the exocrine pancreas, and is of importance for multiple aspects of normal islet function, and probably also during impaired glucose tolerance. Single islet blood flow has been difficult to evaluate due to technical limitations. We therefore adapted a hydrogen gas washout technique using microelectrodes to allow such measurements. Platinum micro-electrodes monitored hydrogen gas clearance from individual endogenous and transplanted islets in the pancreas of male Lewis rats and in human and mouse islets implanted under the renal capsule of male athymic mice. Both in the rat endogenous pancreatic islets as well as in the intra-pancreatically transplanted islets, the vascular conductance and blood flow values displayed a highly heterogeneous distribution, varying by factors 6-10 within the same pancreas. The blood flow of human and mouse islet grafts transplanted in athymic mice was approximately 30% lower than that in the surrounding renal parenchyma. The present technique provides unique opportunities to study the islet vascular dysfunction seen after transplantation, but also allows for investigating the effects of genetic and environmental perturbations on islet blood flow at the single islet level in vivo. (C) 2014 The Authors. Published by Elsevier Inc.
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8. |
- Bentzer, Peter, et al.
(författare)
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Endothelin-1 Reduces Microvascular Fluid Permeability through Secondary Release of Prostacyclin in Cat Skeletal Muscle.
- 2002
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 63:1, s. 50-60
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to analyze effects of various plasma concentrations of the vasoconstrictor endothelin-1 on microvascular fluid permeability and on transcapillary fluid exchange. We also analyzed whether the permeability-reducing substance prostacyclin is involved in the permeability effects of endothelin-1, as prostacylin is suggested to be released via ET(B) receptor stimulation. The study was performed on an autoperfused cat calf muscle preparation, and a capillary filtration coefficient (CFC) technique was used to estimate variations in microvascular fluid permeability (conductivity). Intraarterial infusion of endothelin-1 in low doses (5 and 10 ng/min/100 g muscle) caused transcapillary absorption, whereas higher doses (20-40 ng/min/100 g) induced filtration despite further vasoconstriction. Low-dose endothelin-1 had no significant effect on CFC, while CFC was reduced to at most 55% of baseline at higher doses (P < 0.01). Simultaneous local intraarterial infusion of the prostacyclin synthesis inhibitor tranylcypromine restored CFC to 114% of baseline (P < 0.01) and further increased vascular resistance. A low, nonvasodilator dose of prostacyclin given intravenously counteracted the tranylcypromine effect on CFC. The decreased CFC induced by a high dose of endothelin-1 was counteracted by the ET(B) receptor antagonist BQ-788 with no change in vascular resistance (P < 0.05). We conclude that the decreased CFC following high doses of endothelin-1 can be attributed to a decrease in microvascular hydraulic conductivity, mediated by secondary release of prostacylin via stimulation of the ET(B) receptor. Endothelin-1 may induce edema through postcapillary vasoconstriction. (c)2001 Elsevier Science.
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9. |
- Bergkvist, Max, et al.
(författare)
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Assessment of microcirculation of the skin using Tissue Viability Imaging: A promising technique for detecting venous stasis in the skin
- 2015
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Ingår i: Microvascular Research. - : Elsevier. - 0026-2862 .- 1095-9319. ; 101, s. 20-25
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Tidskriftsartikel (refereegranskat)abstract
- Background: : Venous occlusion in the skin is difficult to detect by existing measurement techniques. Our aim was to find out whether Tissue Viability Imaging (TiVi) was better at detecting venous occlusion by comparing it with results of laser Doppler flowmetry (LDF) during graded arterial and venous stasis in human forearm skin. Methods: : Arterial and venous occlusions were simulated in 10 healthy volunteers by inflating a blood pressure cuff around the upper right arm. Changes in the concentration of red blood cells (RBC) were measured using TiVi, while skin perfusion and concentration of moving red blood cells (CMBC) were measured using static indices of LDF during exsanguination and subsequent arterial occlusion, postocclusive reactive hyperaemia, and graded increasing and decreasing venous stasis. Results: : During arterial occlusion there was a significant reduction in the mean concentration of RBC from baseline, as well as in perfusion and CMBC (p less than 0.008). Venous occlusion resulted in a significant 28% increase in the concentration of RBC (p = 0.002), but no significant change in perfusion (mean change -14%) while CMBC decreased significantly by 24% (p = 0.02). With stepwise increasing occlusion pressures there was a significant rise in the TiVi index and reduction in perfusion (p = 0.008), while the reverse was seen when venous flow was gradually restored. Conclusion: : The concentration of RBC measured with TiVi changes rapidly and consistently during both total and partial arterial and venous occlusions, while the changes in perfusion, measured by LDF, were less consistent This suggests that TiVi could be a more useful, non-invasive clinical monitoring tool for detecting venous stasis in the skin than LDF.
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10. |
- Bergkvist, Max, et al.
(författare)
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Assessment of oxygenation with polarized light spectroscopy enables new means for detecting vascular events in the skin
- 2020
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 130
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Impaired oxygenation in the skin may occur in disease states and after reconstructive surgery. We used tissue viability imaging (TiVi) to measure changes in oxygenation and deoxygenation of haemoglobin in an in vitro model and in the dermal microcirculation of healthy individuals. Materials and methods: Oxygenation was measured in human whole blood with different levels of oxygenation. In healthy subjects, changes in red blood cell concentration (C-RBC,(TiVi)), oxygenation (Delta C-OH,(TiVi)) and deoxygenation (Delta C-DOH,(TiVi)) of haemoglobin were measured during and after arterial and venous occlusion using TiVi and were compared with measurements from the enhanced perfusion and oxygen saturation system (EPOS). Results: During arterial occlusion, C-RBC,(TiVi) remained unchanged while Delta C-OH,(TiVi) decreased to -44.2 (10.4) AU (p = 0.04), as compared to baseline. After release, C-RBC,C-TiVi increased to 39.2 (18.8) AU (p < 0.001), Delta C-OH,C-TiVi increased to 38.5. During venous occlusion, C-RBC,C-TiVi increased to 28.9 (11.2) AU (p < 0.001), Delta C-OH,C-TiVi decreased to -52.2 (46.1) AU (p < 0.001) compared to baseline after 5 min of venous occlusion. There was a significant correlation between the TiVi Oxygen Mapper and EPOS, for arterial (r = 0.92, p < 0.001) and venous occlusion (r = 0.87, p < 0.001), respectively. Conclusion: This study shows that TiVi can measure trends in oxygenation and deoxygenation of haemoglobin during arterial and venous stasis in healthy individuals.
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11. |
- Bunke, Josefine, et al.
(författare)
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Extended-wavelength diffuse reflectance spectroscopy for a comprehensive view of blood perfusion and tissue response in human forearm skin
- 2019
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 124, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to investigate the possibility of using extended-wavelength diffuse reflectance spectroscopy (EW-DRS) to measure tissue response related to blood perfusion. The study was performed on a model that we have previously found to be useful for studying techniques for perfusion monitoring following the injection of epinephrine in a local anesthetic in the human forearm.METHODS: Nine healthy subjects were included in the study. Spectroscopy was performed with an EW-DRS system using a combination of two spectrometers to resolve light in the visible (350 nm to 1100 nm) and the near-infrared regions (900 nm to 1700 nm). The change in signal upon the injection of lidocaine (20 mg/ml) + epinephrine (12.5 μg/ml) (LIDO +EPI), compared to a control injection with saline (9 mg/ml), was investigated.RESULTS: Injection of lidocaine + epinephrine (12.5 μg/ml) caused a change in the EW-DRS signal in the wavelength intervals 510 to 610 nm, known to change upon deoxygenation of hemoglobin. When examining the full wavelength range (450 to 1550 nm) a decrease in reflectance upon LIDO +EPI injection was observed, suggesting that the broader spectrum provides more detailed information on the tissue response. The time to stable hypoperfusion was found to be 2.6 min.CONCLUSIONS: EW-DRS appears to be a promising technique for monitoring perfusion, and could provide a useful tool in plastic and reconstructive surgery. The broad spectrum provides detailed information on the molecular changes taking place in the tissue. However, the technique must be thoroughly validated before it can be implemented in clinical practice.
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12. |
- Detert, Hedvig, et al.
(författare)
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Microcirculatory response to cold stress test in the healthy hand
- 2023
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 148
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Cold sensitivity of the fingers is common in several conditions. It has been linked to digital vasospasm, microvascular dysfunction, and neural mechanisms. This study aimed to investigate the normal digital micro-vascular response to a cold stress test in healthy individuals using Laser Speckle Contrast Imaging (LSCI).Methods: Twenty-six healthy individuals, mean age 31 (SD 9) years were included. Skin perfusion of digits II-V was measured using Laser Speckle Contrast Imaging before and after a standardized cold stress test. Changes in skin perfusion from baseline were analyzed between hands, digits, and sexes.Results: Skin perfusion was significantly (p < 0.0001) affected by cold provocation in both the cold exposed and the contralateral hands in all participants of the study. This effect was significantly different between the radial (digit II and III) and the ulnar (digit V) side of the hands (p < 0.001). There was a trend towards a larger decrease in perfusion in men (ns), and a faster recovery to baseline values in women (ns). A larger inter subject variability was seen in perfusion values in women.Conclusions: The normal microvascular response to cold provocation may involve both centrally and regionally mediated processes. When exposing one hand to a cold stress test, the contralateral hand responds with simul-taneous but smaller decreases in perfusion.
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13. |
- Dinsdale, Graham, et al.
(författare)
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Intra-and inter-observer reliability of nailfold videocapillaroscopy - A possible outcome measure for systemic sclerosis-related microangiopathy
- 2017
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 112, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Our aim was to assess the reliability of nailfold capillary assessment in terms of image evaluability, image severity grade ('normal', 'early', 'active', 'late'), capillary density, capillary (apex) width, and presence of giant capillaries, and also to gain further insight into differences in these parameters between patients with systemic sclerosis (SSc), patients with primary Raynaud's phenomenon (PRP) and healthy control subjects.METHODS: Videocapillaroscopy images (magnification 300×) were acquired from all 10 digits from 173 participants: 101 patients with SSc, 22 with PRP and 50 healthy controls. Ten capillaroscopy experts from 7 European centres evaluated the images. Custom image mark-up software allowed extraction of the following outcome measures: overall grade ('normal', 'early', 'active', 'late', 'non-specific', or 'ungradeable'), capillary density (vessels/mm), mean vessel apical width, and presence of giant capillaries.RESULTS: Observers analysed a median of 129 images each. Evaluability (i.e. the availability of measures) varied across outcome measures (e.g. 73.0% for density and 46.2% for overall grade in patients with SSc). Intra-observer reliability for evaluability was consistently higher than inter- (e.g. for density, intra-class correlation coefficient [ICC] was 0.71 within and 0.14 between observers). Conditional on evaluability, both intra- and inter-observer reliability were high for grade (ICC 0.93 and 0.78 respectively), density (0.91 and 0.64) and width (0.91 and 0.85).CONCLUSIONS: Evaluability is one of the major challenges in assessing nailfold capillaries. However, when images are evaluable, the high intra- and inter-reliabilities suggest that overall image grade, capillary density and apex width have potential as outcome measures in longitudinal studies.
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14. |
- Dinsdale, Graham, et al.
(författare)
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Quantitative outcome measures for systemic sclerosis-related Microangiopathy – Reliability of image acquisition in Nailfold Capillaroscopy
- 2017
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 113, s. 56-59
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Tidskriftsartikel (refereegranskat)abstract
- Background Nailfold capillaroscopic parameters hold increasing promise as outcome measures for clinical trials in systemic sclerosis (SSc). Their inclusion as outcomes would often naturally require capillaroscopy images to be captured at several time points during any one study. Our objective was to assess repeatability of image acquisition (which has been little studied), as well as of measurement. Method 41 patients (26 with SSc, 15 with primary Raynaud's phenomenon) and 10 healthy controls returned for repeat high-magnification (300 ×) videocapillaroscopy mosaic imaging of 10 digits one week after initial imaging (as part of a larger study of reliability). Images were assessed in a random order by an expert blinded observer and 4 outcome measures extracted: (1) overall image grade and then (where possible) distal vessel locations were marked, allowing (2) vessel density (across the whole nailfold) to be calculated (3) apex width measurement and (4) giant vessel count. Intra-rater, intra-visit and intra-rater inter-visit (baseline vs. 1 week) reliability were examined in 475 and 392 images respectively. A linear, mixed-effects model was used to estimate variance components, from which intra-class correlation coefficients (ICCs) were determined. Results Intra-visit and inter-visit reliability estimates (ICCs) were (respectively): overall image grade, 0.97 and 0.90; vessel density, 0.92 and 0.65; mean vessel width, 0.91 and 0.79; presence of giant capillary, 0.68 and 0.56. These estimates were conditional on each parameter being measurable. Conclusion Within-operator image analysis and acquisition are reproducible. Quantitative nailfold capillaroscopy, at least with a single observer, provides reliable outcome measures for clinical studies including randomised controlled trials.
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15. |
- Droog Tesselaar, Erik, et al.
(författare)
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A protocol for iontophoresis of acetylcholine and sodium nitroprusside that minimises nonspecific vasodilatory effects
- 2004
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Ingår i: Microvascular research. - : Elsevier BV. - 0026-2862. ; 67:2, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Iontophoresis of vasoactive substances is a promising tool for studying pharmacological aspects of the (patho)physiology of the microvasculature. However, nonspecific microvascular responses are a common problem in most protocols used. We studied the effect of current density (mA/cm2), charge density (mC/cm2), drug concentration (mass %) and vehicle concentration (M) on the nonspecific vasodilatation during iontophoresis of sodium chloride, acetylcholine (ACh) and sodium nitroprusside (SNP). We found that nonspecific vasodilatation depended on current density and charge density in both anodal and cathodal iontophoresis. The responses to ACh and SNP were dependent on current density, charge density and drug concentration. We found that by limiting current density (<0.01 mA/cm2) and charge density (<7.8 mC/cm2) and with adjusted concentrations for drugs and vehicles, it is possible to prevent nonspecific effects during iontophoresis of ACh and SNP, while maximum drug effects (plateaus in the dose–response curves) are still obtained. These new findings are important for future iontophoresis studies in which vasoactive drugs are used to assess microvascular function because the presented approach has advantages compared to older techniques, which mainly have attempted to suppress or compensate for the nonspecific responses during iontophoresis by the use of local anaesthetics or the measurement of drug-minus-vehicle responses, both of which present well-known experimental shortcomings.
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16. |
- Dubniks, Maris, et al.
(författare)
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Change in plasma volume from a state of hyper-, normo- or hypovolemia with or without noradrenalin infusion in the rat.
- 2008
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 76, s. 75-79
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Tidskriftsartikel (refereegranskat)abstract
- Fluid substitution is important in critically ill patients to maintain normovolemia, but there is always a risk that the treatment is too aggressive resulting in fluid overload, or is insufficient with maintenance of hypovolemia. The present study on the rat aims at evaluating the change in plasma volume after 2.5 h from a state of hyper- and hypovolemia. The analysis was made without and with noradrenalin infusion, based on the fact that noradrenalin infusion is a common drug to maintain an adequate arterial pressure, and noradrenalin may induce transcapillary filtration. Plasma volume was determined at baseline and at the end of the experiments with a (125)I-albumin tracer technique. Arterial and central venous pressure, and urine output were recorded. We showed that induction of hypervolemia with a 5% albumin solution (15 ml/kg) resulted in successive loss of plasma volume, which was aggravated with noradrenalin infusion. Hypovolemia induced by hemorrhage (15 ml/kg) resulted in transcapillary absorption, an absorption almost abolished during noradrenalin infusion. There was no plasma volume loss in the sham group. Urine output was higher under hypervolemia than under normovolemia, which in turn was higher than under hypovolemia. We conclude that hypervolemia induces plasma volume loss, which is aggravated by noradrenalin infusion. The compensatory absorption effect after hemorrhage is counteracted by noradrenalin. The results can be explained by differences in hydrostatic capillary pressure via alterations in arterial and venous pressure, according to the 2-pore theory of transcapillary fluid exchange.
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17. |
- Elawa, Sherif, et al.
(författare)
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The microvascular response in the skin to topical application of methyl nicotinate : Effect of concentration and variation between skin sites
- 2019
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 124, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMethyl nicotinate (MN) induces a local cutaneous erythema in the skin and may be used as a local provocation in the assessment of microcirculation and skin viability. The aims were to measure the effects of increasing doses of MN, to find the concentration that yields the most reproducible effect from day to day and between sites, and to study the variation between skin sites.MethodsMicrovascular responses to topically applied MN at different concentrations were measured in 12 subjects on separate days and on contralateral sides, using laserspeckle contrast imaging (LSCI). MN effects were measured in four different body sites.ResultsAt 20 mmol/L, the response to MN was most reproducible day-to-day and site-to-site, and resulted in a plateau response between 5 and 20 min after application.The skin region of the lower back had a lower perfusion value compared to the epigastric region (p = 0.007). When responses were compared to nearby, unprovoked areas, a significantly larger increase in perfusion was seen in the forearm, compared to all other anatomical sites (p < 0.03).ConclusionA concentration of 20 mmol/L MN generated the most reproducible microvascular response in the skin. The response varies between different body sites.
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18. |
- Emrani, Zahra, et al.
(författare)
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Capillary density : An important parameter in nailfold capillaroscopy
- 2017
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Ingår i: Microvascular Research. - Netherland : Elsevier. - 0026-2862 .- 1095-9319. ; 109, s. 7-18
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Tidskriftsartikel (refereegranskat)abstract
- Nailfold capillaroscopy is one of the various noninvasive bioengineering methods used to investigate skin microcirculation. It is an effective examination for assessing microvascular changes in the peripheral circulation; hence it has a significant role for the diagnosis of Systemic sclerosis with the classic changes of giant capillaries as well as the decline in capillary density with capillary dropout. The decline in capillary density is one of microangiopathic features existing in connective tissue disease. It is detectable with nailfold capillaroscopy. This parameter is assessed by applying quantitative measurement. In this article, we reviewed a common method for calculating the capillary density and the relation between the number of capillaries as well as the existence of digital ulcers, pulmonary arterial hypertension, autoantibodies, scleroderma patterns and different scoring system.
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19. |
- Erjefält, Jonas, et al.
(författare)
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Microcirculation-derived factors in airway epithelial repair in vivo
- 1994
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 48:2, s. 161-178
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Tidskriftsartikel (refereegranskat)abstract
- Airway epithelial repair, by cell migration over a denuded, intact basement membrane, occurs rapidly in vivo. The present study examines microcirculation-derived factors in the reepithelialization process in the guinea pig. A well-defined tracheal zone was gently deepithelialized; no bleeding occurred and the basement membrane was left intact. Plasma exudation was visualized by use of iv colloidal gold (diameter: 5 nm) or fluoresceinisothiocyanate-labeled dextran. Scanning and transmission electron microscopy confirmed the migration of epithelial cells and, additionally, allowed us to examine the presence of an extracellular matrix gel and leukocytes on the denuded basement membrane. Fibronectin was analyzed by immunocytochemistry. Following epithelial removal plasma promptly extravasates and produces a fibrin-fibronectin gel to cover the denuded basement membrane. Epithelial cells dedifferentiate, flatten, and migrate rapidly (several micron/min) beneath the plasma-derived gel. Within 30 min the gel contains numerous leukocytes, some of which are eosinophils. Plasma exudes into the gel until about 8 hr by which time the entire denuded zone (800 microns) is covered by squamous epithelium. The fibrin-fibronectin gel is suggested to be exclusively plasma-derived. In conclusion, reepithelialization in vivo occurs beneath a gel containing adhesive plasma proteins and leukocytes. We suggest that a plasma exudate provides immediate cover of denuded airway basement membrane and that plasma- and leukocyte-derived factors contribute essentially to reepithelialization in vivo.
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20. |
- Farnebo, Simon, et al.
(författare)
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Hyperaemic changes in forearm skin perfusion and RBC concentration after increasing occlusion times
- 2010
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Ingår i: MICROVASCULAR RESEARCH. - : Elsevier Science B.V., Amsterdam. - 0026-2862. ; 80:3, s. 412-416
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Tidskriftsartikel (refereegranskat)abstract
- Tissue occlusion and the hyperaemic response upon reperfusion can be used as a tool to assess microvascular function in various vascular diseases. Currently, laser Doppler flowmetry (LDF) is applied most often to measure hyperaemic responses. In this study, we have applied tissue viability imaging (TiVi) and LDF to measure the change in red blood cell concentration and perfusion in the skin after occlusions of the forearm with increasing duration. We have found that there is a strong correlation between the changes in perfusion and red blood cell (RBC) concentration during post-occlusive hyperaemia (perfusion: r = 0.80; RBC concentration: r = 0.94). This correlation increases with longer occlusion durations (1, 5 and 10 min). Furthermore, for both perfusion and RBC concentration, the maximum responses (perfusion: r(2) = 0.59; RBC concentration: r(2) = 0.78) and the recovery times (perfusion: r(2) = 0.62; RBC concentration: r(2) = 0.91) increase linearly with the duration of the occlusion. Maximum responses and recovery times were more reproducible for RBC concentration (as measured with TiVi) than for perfusion (as measured with LDF). These results show that perfusion and RBC concentration are related during post-occlusive hyperaemia and that TiVi can be used as a tool in the assessment of hyperaemic responses that has advantages in terms of reproducibility, sensitivity and ease of use.
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21. |
- Fatemi, Alimohammad, et al.
(författare)
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Nailfold microvascular changes in patients with systemic lupus erythematosus and their associative factors
- 2019
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 126
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to determine capillaroscopic changes in patients with systemic lupus erythematosus (SLE) and their predictors. Methods: Fifty-nine SLE patients and 31 controls were enrolled in a cross-sectional study. Nailfold capillaroscopy examinations were performed, and qualitative semi-quantitative and quantitative parameters were evaluated in all fingers. Demographic features and lupus characteristics, such as renal involvement, medications, laboratory data, disease activity (SLEDAI) and damage, were recorded. The predictors of capillaroscopic abnormalities were obtained by backward stepwise regression analysis. Results: Capillary numbers of right hands were significantly lower in patients than in controls [8.74 (1.66) vs. 9.63 (1.80), P = 0.0001]. Capillaries were wider in patients than in controls in right [56.32 pm (16.76) vs. 50.43 mu m (10.16), P = 0.002] and left hands [54.40 (15.02) vs. 49.71 (9.77), P = 0.005]. Capillaries were shorter in SLE patients than in controls. Multivariate analysis revealed that the main associative factors of microvascular abnormalities were gender, drinking tea and hydroxychloroquine use for giant capillaries, SLEDAI and low C3 for avascularity and age, lupus nephritis and corticosteroid use for ramification. Conclusion: Most nailfold capillaroscopic abnormalities were more common in SLE patients than in controls. Hydroxychloroquine, corticosteroids, SLEDAI, low complement and lupus nephritis may be the major prognostic factors for microvascular changes in SLE patients.
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22. |
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23. |
- Freccero, Carolin, et al.
(författare)
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The influence of wavelength and probe configuration on findings of a skin vasoconstriction test when using laser Doppler perfusion devices.
- 2006
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 71:Jan 3, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to establish the degree to which a standardized test based on laser Doppler blood flow measurement is dependent on the particular equipment set-up being used. For this purpose, we examined finger skin blood flow with laser Doppler instruments in 20 healthy subjects. In laser Doppler perfusion monitoring (LDPM), we used a custom-made probe with two detecting fibers placed 0.25 and 1.2 min from the illuminating fiber, respectively, and two laser Doppler perfusion imagers (LDPI) with a wavelength of 632.8 nm and 780 rim, respectively. Warming of the hand was achieved with a Peltier element, and reflex vasoconstriction was induced by immersing the other hand for 3 min into a water bath kept at 15 degrees C. As a measure for the change in skin blood flow, a vasoconstriction index (VAC: cooling/before cooling) was calculated and used for the comparison of the different devices. VAC values gathered around 0.6 for all devices. However, LDPI with a wavelength of 632.9 nm showed a slightly higher VAC index, and the difference was significant. We conclude that using a standardized test is the most appropriate for monitoring changes in blood flow rather than recording and comparing discrete values in intermittent recordings. Although a difference was noted when comparing the devices, different fiber separations and wavelengths seem then to be of little consequence. (c) 2005 Published by Elsevier Inc.
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24. |
- Fredriksson, Ingemar, et al.
(författare)
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Measurement depth and volume in laser Doppler flowmetry
- 2009
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 78:1, s. 4-13
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Tidskriftsartikel (refereegranskat)abstract
- A new method for estimating the measurement depth and volume in laser Doppler flowmetry (LDF) is presented. The method is based on Monte Carlo simulations of light propagation in tissue. The contribution from each individual Doppler shift is calculated and thereby multiple Doppler shifts are handled correctly. Different LDF setups for both probe based (0.0, 0.25, 0.5, and 1.2 mm source-detector separation) and imaging systems (0.5 and 2.0 mm beam diameter) are considered, at the wavelengths 543 nm, 633 nm, and 780 nm. Non-linear speckle pattern effects are accounted for in the imaging system setups. The effects of tissue optical properties, blood concentration, and blood oxygen saturation are evaluated using both homogeneous tissue models and a layered skin model. The results show that the effect on the measurement depth of changing tissue properties is comparable to the effect of changing the system setup, e.g. source-detector separation and wavelength. Skin pigmentation was found to have a negligible effect on the measurement depth. Examples of measurement depths are (values are given for a probe based system with 0.25 mm source-detector separation and an imaging system with a 0.5 mm beam diameter, respectively, both operating at 780 nm): muscle - 0.55/0.79 mm; liver - 0.40/0.53 mm; gray matter - 0.48/0.68 mm; white matter - 0.20/0.20 mm; index finger pulp - 0.41/0.53 mm; forearm skin - 0.53/0.56 mm; heat provoked forearm skin - 0.66/0.67 mm.
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25. |
- Girkantaite, Zivile, et al.
(författare)
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Laser Doppler flowmetry evaluation of skin microvascular endothelial function in patients with metabolic syndrome
- 2022
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Background: Metabolic syndrome (MetS) is associated with high cardiovascular morbidity and mortality, and endothelial dysfunction is an early pathogenetic event in the MetS. Lifestyle changes and pharmacological intervention might partly restore endothelial function in MetS. Whereas an optimal non-invasive test for endothelial dysfunction is still being sought, the aim of this study was to assess the relationship between changes in skin microvascular endothelial function, detected by Laser Doppler flowmetry, and cardiovascular risk factors (CVRFs) of patients with MetS. Design and methods: 3081 patients (1865 women and 1216 men, mean age 53 ± 6 years) with MetS were enrolled in the study, which was conducted during the period of 2010–2014 at Vilnius University Hospital Santaros Klinikos. Skin microvascular endothelial function was evaluated using the Laser Doppler flowmetry in combination with the post-occlusive reactive hyperaemia test. The percentage change of flow from peak to the rest flow (PF-RF) was calculated and used as the main measure of endothelial function. Results: The study showed that decrease in flow-mediated dilatation reflected by PF-RF was associated with increased triglycerides (p = 0.002), male sex (p < 0.001), and diabetes (p = 0.002). Patients with quite a few CVRFs (body mass index ≥25 kg/m2, smoking, diabetes, arterial hypertension, a positive history of dyslipidaemia) had significantly lower PF-RF score than patients only with one of these risk factors (p < 0.001). Conclusions: Changes in skin microvascular endothelial function are significantly associated with most CVRFs and depend on the number of CVRFs.
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26. |
- Golster, Helena, et al.
(författare)
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Red Blood Cell Velocity and Volumetric Flow Assessment by Enhanced High-Resolution Laser Doppler Imaging in Separate Vessels of the Hamster Cheek Pouch Microcirculation
- 1999
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 58:1, s. 62-73
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Tidskriftsartikel (refereegranskat)abstract
- An enhanced high-resolution laser Doppler imager (EHR-LDI), configured to fit the demands of a measurement area containing separate microvessels, was evaluated for perfusion measurements in hamster cheek pouch preparations during ischemia, reperfusion, and pharmacologically induced vasodilation and vasoconstriction. Measurements in separate microvessels where the laser beam was smaller than the vessel diameter were referred to as red blood cell (RBC) velocity estimates, as previously validated in vitro, whereas a relative flow index, RFI (mean RBC velocity/tissue area), was introduced as a volumetric flow measure. Microvessel diameter and RBC velocity changes during ischemia, reperfusion, as well as during vasoconstriction and vasodilation correlated to the data obtained from the microscope. Correspondingly, during the described provocations anticipated volumetric flow changes were registered as changes in the RFI. When data on intravessel RBC velocity profiles are presented they reflect a parabolic flow profile usually seen in this size microvessel. The EHR-LDI appears a promising tool for investigation of the microvasculature, as it almost simultaneously provides information on relative changes of both in vivo RBC velocity and volumetric flow (RFI), although the latter estimate needs to be further refined.
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27. |
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28. |
- Henricson, Joakim, et al.
(författare)
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Assessment of microvascular function by study of the dose‐response effects of iontophoretically applied drugs (acetylcholine and sodium nitroprusside) : Methods and comparison with in vitro studies
- 2007
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 73:2, s. 143-149
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Tidskriftsartikel (refereegranskat)abstract
- Current knowledge about vascular function stems mainly from pharmacological in vitro studies using mounted vascular strips on a strain gauge. We know of no paper that has systematically examined the possibility of assessing the conventional dose–response effects of iontophoresis and laser Doppler investigation of vasoactive substances and compared those relations to data obtained from strips mounted on a strain gauge. We used the vasoactive substances acetylcholine (endothelium dependent) and sodium nitroprusside (endothelium independent) and an antagonist (atropine) to enable further investigations in the receptor physiology of iontophoresis. Dose–response curves from the iontophoresis experiments showed close similarity to those obtained by vascular strips mounted on a strain gauge. The coefficient of variation (CV) of the dose–response factors found in iontophoresis (both inter and intra experimental variability) was low. The iontophoretic effective dose of 50% (ED50) for acetylcholine and nitroprusside had only CVs of 25% and 26%, respectively, compared with 71% and 77% for the vascular strips. Acetylcholine-induced response was antagonized by iontophoresis of atropine. Contrary to expectations, this antagonism was not competitive. The results show that iontophoresis in combination with laser Doppler technology produces reproducible and reliable dose–response curves that picture the vascular effects of vasoactive drugs.
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29. |
- Henricson, Joakim, et al.
(författare)
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Tissue viability imaging : Microvascular response to vasoactive drugs induced by iontophoresis
- 2009
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 78:2, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- When one is studying the physiology of the cutaneous microcirculation there is a need for relevant non-invasive and versatile techniques. In this study we used a new optical device, the tissue viability imager (TiVi), to map changes in cutaneous microvascular concentrations of red blood cells during iontophoresis of vasoactive substances (noradrenaline (NA) and phenylephrine (Phe) for vasoconstriction and acetylcholine (ACh) and sodium nitroprusside (SNP) for vasodilatation). We aimed to present data both individually and pooled, using a four-variable logistic dose response model that is commonly used in similar in vitro vascular studies. The accuracy of the TiVi was also investigated by calculating the coefficient of variation and comparing it with similar tests previously done using laser Doppler imaging. Tests were also performed using the TiVi and LDPI simultaneously to further compare the two methods. Results showed that the TiVi is capable of quantifying vascular responses to iontophorised noradrenaline and phenylephrine without the need to increase background flow first. Fitting the TiVi data to the dose response model resulted in ED50-values with narrow confidence intervals and acceptable r2 values. Mean ED50-values for the TiVi did not differ significantly from similar values obtained using laser Doppler. Results further seem to suggest that when the blood perfusion increases during vasodilatation in skin the initial phase relies mainly on an increase in red blood cell concentration whereas the further perfusion increase is due to an increase in red blood cell velocity.
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30. |
- Hjalmarsson, Clara, 1969, et al.
(författare)
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Electron microscopic evaluation of the endothelial surface layer of glomerular capillaries.
- 2004
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Ingår i: Microvascular research. - : Elsevier BV. - 0026-2862. ; 67:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Recent data from various vascular beds suggest that a layer of mucopolysaccharides covering the endothelial cells play an important role in transport processes, among others. In this study, electron microscopy (EM) was used to explore the presence of an endothelial surface layer (ESL) in rat glomerular capillaries. We adopted various fixation and labeling techniques, as follows: (1) negatively charged lipid particles were used as a tracer that was expected to be excluded from the ESL. The density of intravascular lipid particles in flow-arrested capillaries was 89% lower in a 200-nm periendothelial area than in the rest of the luminal space (n = 6 rats, P < 0.001); (2) podocytes of cryofixed fresh tissue had a 20-nm extramembranous coat, interpreted as the true glycocalyx; the coat was less expressed on the endothelium; (3) on unfixed endothelial cells, colloidal lanthanum labeled a 60-nm-thick layer, occasionally forming lumps; (4) perfusion with a fluorocarbon-based oxygen-carrying fixative, followed by tannic acid contrast enhancement, revealed an extensive (> 200 nm) ESL not previously described; however, this finding was restricted to superficial glomerular capillaries; (5) Cupromeronic Blue cytochemistry displayed a loose proteoglycan network in fenestral openings and, occasionally, a semiordered ESL; (6) ferricyanide-reduced osmication resulted in increased numbers of fenestral diaphragms. In conclusion, this study provides novel morphological evidence to support the presence of a significant glomerular ESL.
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31. |
- Horiuchi, Yoshihito, et al.
(författare)
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Role of histamine release in nonspecific vasodilatation during anodal and cathodal iontophoresis
- 2004
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Ingår i: Microvascular research. - : Elsevier BV. - 0026-2862. ; 67:2, s. 192-196
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Tidskriftsartikel (refereegranskat)abstract
- Nonspecific vasodilatation during iontophoresis is an important confounding factor in experimental pharmacology. In this investigation, we studied the involvement of sensory nerves and histamine-related reactions in causing nonspecific vasodilatation in a model of anodal and cathodal iontophoresis of sodium chloride. Firstly, we applied a mixture of local anesthetic (EMLA) cream to confirm its suppressive effect on nonspecific vasodilatation and to measure its efficacy in three different dosages (duration: 1, 2, and 3 h). We then investigated the role of histamine in nonspecific vasodilatation by giving an oral antihistamine drug (cetirizine) to subjects who had and had not been given EMLA. We found substantial suppression of the nonspecific vasodilatation in all EMLA-treated groups (all dosages) compared with untreated controls (with suppression rates of 60–65%). Dosage had no significant effect. A further suppression of nonspecific vasodilatation was seen after oral cetirizine during anodal and cathodal iontophoresis in both EMLA-treated and untreated groups. The antihistamine effect was most pronounced during anodal iontophoresis. These results suggest a histaminergic increase in perfusion that may be independent of neurogenic mechanisms and depend on polarity (anode or cathode). Local nerve blocks (EMLA) together with cetirizine may therefore be used to reduce nonspecific vasodilatation in both anodal and cathodal iontophoresis.
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32. |
- Hultborn, Ragnar, 1946
(författare)
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Blood flow, volume and arterio-venous passages in induced mammary tumours of the rat
- 2018
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 116, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- Objective To study blood flow, vascular volume and arterio-venous passages in induced mammary tumours of the rat to characterize parameters possibly responsible for tumour hyponutrition. Method Dimethylbenzanthracene-induced mammary tumours in Sprague-Dawley rats were studied. Regional blood flow was studied by use of the radioactive microsphere tracer technique using 141Cerium-labelled 15 μm spheres coinjected into the left cardiac ventricle with 125Iodine-labelled 25 μm spheres. Blood volume was studied by use of 125Iodine- or 99mTechnetium-labelled human serum albumin, the latter allowing autoradiography of tumour sections for visualization of flow and volume. Results Twenty-seven rats with 170 tumours had a mean tumour blood flow of 48 and 67 mL × min− 1 × 100 g− 1 using 15 and 25 μm sphere data, respectively, indicating a significant passage through vessels between 15 and 25 μm. The lungs showed a “nominal bronchial” blood flow of 260 and 135 mL × min− 1 × 100 g− 1 for the 15 and 25 μm spheres, respectively, indicating pulmonary trapping, particularly of small spheres passing the systemic circulation in vessels larger than 15 μm. There was a positive correlation between the total tumour blood flow within individual rats and trapped spheres of both dimensions in the lungs, indicating shunts also larger than 25 μm. Normal tissues disclosed only small differences in regional blood flow as measured by the two spheres. Blood volume was studied in 20 rats with 120 tumours, with a vascular volume of 3.6 mL × 100 g− 1 representing a blood turnover > 15 times/min. Blood volume co-localized with perfusion as seen in autoradiographs. Conclusion In induced rat mammary tumours, a high fraction of blood, 28%, passes arterio-venous vessels between 15 and 25 μm and there also exist passages > 25 μm. These findings indicate that the functional capacity of the tumour vascular bed might be impaired, adding to the abnormal microenvironment of tumours. © 2017 Elsevier Inc.
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33. |
- Hultman, Martin, 1992-, et al.
(författare)
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Comprehensive imaging of microcirculatory changes in the foot during endovascular intervention - A technical feasibility study
- 2022
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Ingår i: Microvascular Research. - Maryland Heights, MO, United States : Academic Press. - 0026-2862 .- 1095-9319. ; 141
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Tidskriftsartikel (refereegranskat)abstract
- Chronic limb-threatening ischemia (CLTI) has a major impact on patient's lives and is associated with a heavy health care burden with high morbidity and mortality. Treatment by endovascular intervention is mostly based on macrocirculatory information from angiography and does not consider the microcirculation. Despite successful endovascular intervention according to angiographic criteria, a proportion of patients fail to heal ischemic lesions. This might be due to impaired microvascular perfusion and variations in the supply to different angiosomes. Non-invasive optical techniques for microcirculatory perfusion and oxygen saturation imaging have the potential to provide the interventionist with additional information in real-time, supporting clinical decisions during the intervention. This study presents a novel multimodal imaging system, based on multi-exposure laser speckle contrast imaging and multi-spectral imaging, for continuous use during endovascular intervention. The results during intervention display spatiotemporal changes in the microcirculation compatible with expected physiological reactions during balloon dilation, with initially induced ischemia followed by a restored perfusion, and local administration of a vasodilator inducing hyperemia. We also present perioperative and postoperative follow-up measurements with a pulsatile microcirculation perfusion. Finally, cases of spatial heterogeneity in the observed oxygen saturation and perfusion are discussed. In conclusion, this technical feasibility study shows the potential of the methodology to characterize changes in microcirculation before, during, and after endovascular intervention.
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34. |
- Hultman, Martin, et al.
(författare)
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Flowmotion imaging analysis of spatiotemporal variations in skin microcirculatory perfusion
- 2023
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 146
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Tidskriftsartikel (refereegranskat)abstract
- Background: Flowmotion is the rhythmical variations in measured skin blood flow that arise due to global and local regulation of the vessels and can be studied using frequency analysis of time-resolved blood flow signals. It has the potential to reveal clinically useful information about microvascular diseases, but the spatial heteroge-neous nature of the microvasculature makes interpretation difficult. However, recent technological advances in multi-exposure laser speckle contrast imaging (MELSCI) enable new possibilities for simultaneously studying spatial and temporal variations in flowmotion.Aim: To develop a method for flowmotion analysis of MELSCI perfusion images. Furthermore, to investigate the spatial and temporal variations in flowmotion in forearm baseline skin perfusion.Method: In four healthy subjects, forearm skin perfusion was imaged at 15.6 fps for 10 min in baseline. The time -trace signal in each pixel was analyzed using the wavelet transform and summarized in five physiologically relevant frequency intervals, resulting in images of flowmotion. Furthermore, a method for reducing the effect of motion artifacts in the flowmotion analysis was developed.Results: The flowmotion images displayed patterns of high spatial heterogeneity that differed between the fre-quency intervals. The spatial variations in flowmotion, quantified as the coefficient of variation, was between 11 % and 31 % in four subjects. Furthermore, significant temporal variations in flowmotion were also observed, indicating the importance of a spatiotemporal analysis.Conclusion: The new imaging technique reveals significant spatial differences in flowmotion that cannot be ob-tained with single-point measurements. The results indicate that global statistics of flowmotion, such as the mean value in a large region of interest, is more representative of the microcirculation than data measured only in a single point. Therefore, imaging techniques have potential to increase the clinical usefulness of flowmotion analysis.
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35. |
- Hultman, Martin, et al.
(författare)
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Robust analysis of microcirculatory flowmotion during post-occlusive reactive hyperemia
- 2024
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- Background: Flowmotion analysis of the microcirculatory blood flow is a method to extract information about the vessel regulatory function. It has previously shown promise when applied to measurements during a postocclusive reactive hyperemia. However, the reperfusion peak and the following monotonic decline introduces false low frequencies that should not be interpreted as rhythmic vasomotion effect. Aim: To develop and validate a robust method for flowmotion analysis of post-occlusive reactive hyperemia signals. Method: The occlusion-induced reperfusion response contains a typical rapid increase followed by a monotonic decline to baseline. A mathematical model is proposed to detrend this transient part of the signal to enable further flowmotion analysis. The model is validated in 96 measurements on healthy volunteers. Results: Applying the proposed model corrects the flowmotion signal without adding any substantial new false flowmotion components. Conclusion: Future studies should use the proposed method or equivalent when analyzing flowmotion during post-occlusive reactive hyperemia to ensure valid results.
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36. |
- Häggblad, Erik, 1972-, et al.
(författare)
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Reflection Spectroscopy of Analgesized Skin
- 2001
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Ingår i: Microvascular Research. - : ScienceDirect. - 0026-2862 .- 1095-9319. ; 62:3, s. 392-400
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Tidskriftsartikel (refereegranskat)abstract
- Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.
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37. |
- Ingegnoli, Francesca, et al.
(författare)
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A comparison between nailfold capillaroscopy patterns in adulthood in juvenile and adult-onset systemic sclerosis: A EUSTAR exploratory study
- 2015
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 102, s. 19-24
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Qualitative capillaroscopy patterns in juvenile- and adult-onset systemic sclerosis (SSc) were studied in adulthood using data from the EULAR Scleroderma Trials and Research (EUSTAR) database. Methods: Data collected between June 2004 and April 2013 were examined with focus on capillaroscopy. In this retrospective exploratory study, series of patients with juvenile-onset SSc were matched with series of adult-onset SSc having the same gender and autoantibody profile. Results: 30 of 123 patients with juvenile-onset and 2108 of 7133 with adult-onset SSc had data on capillaroscopy. Juvenile-onset SSc showed scleroderma pattern more frequently than adult-onset SSc (93.3% and 88%). The OR was 2.44 and 95% Cl 0.57-10.41. An active scleroderma pattern was present in 58% of juvenile- and 61% of adult-onset SSc. The OR was 0.91 and 95% Cl 0.28-2.93. The late scleroderma pattern was present in 61% of juvenile- and 55.5% of adult-onset SSc. The OR was 1.06 and 95% Cl 0.34-3.56. Conclusion: This is the first exploratory study on the comparison of capillaroscopy between juvenile- and adult-onset SSc in adulthood. Juvenile-onset SSc had an increase prevalence of sderoderma pattern, but a similar distribution of the three patterns was suggested. Further studies are needed to define this issue. (C) 2015 Elsevier Inc. All rights reserved.
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38. |
- Ingegnoli, Francesca, et al.
(författare)
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Nailfold capillaroscopy in systemic sclerosis: Data from the EULAR scleroderma trials and research (EUSTAR) database
- 2013
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 89, s. 122-128
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aims of this study were to obtain cross-sectional data on capillaroscopy in an international multi-center cohort of Systemic Sclerosis (SSc) and to investigate the frequency of the capillaroscopic patterns and their disease-phenotype associations. Methods: Data collected between June 2004 and October 2011 in the EULAR Scleroderma Trials and Research (EUSTAR) registry were examined. Patients' profiles based on clinical and laboratory data were obtained by cluster analysis and the association between profiles and capillaroscopy was investigated by multinomial logistic regression. Results: 62 of the 110 EUSTAR centers entered data on capillaroscopy in the EUSTAR database. 376 of the 2754 patients (13.65%) were classified as scleroderma pattern absent, but non-specific capillary abnormalities were noted in 55.48% of the cases. Four major patients' profiles were identified characterized by a progressive severity for skin involvement, as well as an increased number of systemic manifestations. The "early" and "active" scleroderma patterns were generally observed in patients with mild/moderate skin involvement and a low number of disease manifestations, while the "late" scleroderma pattern was found more frequently in the more severe forms of the disease. Conclusion: These data indicate the importance of capillaroscopy in SSc management and that capillaroscopic patterns are directly related to the extent of organ involvement. (C) 2013 Elsevier Inc. All rights reserved.
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39. |
- Jia, Min, et al.
(författare)
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Tetrahydroxystilbene glucoside-induced relaxation of the superior mesenteric artery via both endothelium-dependent and endothelium-independent mechanisms
- 2019
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 123, s. 42-49
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Tidskriftsartikel (refereegranskat)abstract
- Tetrahydroxystilbene glucoside (TSG) is the main water-soluble component in Polygonum multiflorum Thunb, and it has many cardioprotective effects. Although TSG is able to relax blood vessels, its relaxation of rat superior mesenteric arteries and the underlying mechanism of this process are not clearly understood. The aim of the present study was to use in vivo and in vitro models to investigate the arterial relaxation effect of TSG on rat superior mesenteric arteries and the mechanisms involved. We found that TSG concentration-dependently relaxed the superior mesenteric artery with or without endothelium. The vasorelaxation induced by TSG is not related to the vasodilator derived factor NO but is rather by the inhibition of COX-2 activity and decreased TXA2. We also found that the vasorelaxation induced by TSG was attenuated by 4‑AP. Moreover, TSG also inhibited the contraction induced by an increase in external calcium concentration in Ca2+-free medium plus KCl (60 mM). These results suggest that TSG induces relaxation in mesenteric arterial rings through an endothelium-dependent pathway that involves the inhibition of COX-2 activity and decreased in TXA2 and through an endothelium-independent pathway via opening of a voltage-dependent K+ channel, blockade of Ca2+ influx and release of intracellular Ca2+.
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40. |
- Jonasson, Hanna, et al.
(författare)
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Oxygen saturation, red blood cell tissue fraction and speed resolved perfusion — A new optical method for microcirculatory assessment
- 2015
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 102, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a new fiber-optic system that combines diffuse reflectance spectroscopy (DRS) and laser Doppler Flowmetry (LDF) for a multi-modal assessment of the microcirculation. Quantitative data is achieved with an inverse Monte Carlo algorithm based on an individually adaptive skin model. The output parameters are calculated from the model and given in absolute units: hemoglobin oxygen saturation (%), red blood cell (RBC) tissue fraction (%), and the speed resolved RBC perfusion separated into three speed regions; 0–1 mm/s, 1–10 mm/s and above 10 mm/s (% mm/s). The aim was to explore microcirculatory parameters using the new optical method, integrating DRS and LDF in a joint skin model, during local heating of the dorsal foot and venous and arterial occlusion of the forearm in 23 healthy subjects (age 20–28 years). There were differences in the three speed regions in regard to blood flow changes due to local heating, where perfusion for high speeds increased the most. There was also a high correlation between changes in oxygenation and changes in perfusion for higher speeds. Oxygen saturation at baseline was 44% on foot, increasing to 83% at plateau after heating. The larger increase in perfusion for higher speeds than for lower speeds together with the oxygenation increase during thermal provocation, shows a local thermoregulatory blood flow in presumably arteriolar dermal vessels. In conclusion, there are improved possibilities to assess microcirculation using integrated DRS and LDF in a joint skin model by enabling both oxygenation and speed resolved blood flow assessment simultaneously and in the same skin site. Output parameters in absolute units may also yield new insights about the microcirculatory system.
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41. |
- Jonasson, Hanna, et al.
(författare)
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Post-ischemic skin peak oxygen saturation is associated with cardiovascular risk factors: a Swedish cohort study
- 2022
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to explore the associations between skin microcirculatory function and established cardiovascular risk factors in a large Swedish cohort. As part of the Swedish CArdioPulmonary bioImage Study (SCAPIS), microcirculatory data were acquired at Linko center dot ping University hospital, Linko center dot ping, Sweden during 2016-2017. The subjects, aged 50-64 years, were randomly selected from the national population register. Microcirculatory reactivity was assessed using a 5-min arterial occlusion-release protocol. Comprehensive skin microcirculatory data were continuously acquired by using a fiberoptic probe placed on the lower right arm. After exclusion of missing data (208), 1557 subjects were remaining. Among the parameters, skin microcirculatory peak oxygen saturation after occlusion release, had the strongest relationship to the cardiovascular risk factors. The linear associations between peak oxygen saturation and cardiovascular risk factors were analyzed adjusted for age and sex. We found a negative association with peak oxygen saturation (standardized regression coefficient) for blood pressure (systolic-0.05 (95% CI:-0.10;-0.003) and diastolic-0.05 (-0.10;-0.003)), BMI-0.18 (-0.23;-0.13), waist circumference (males-0.20 (-0.32;-0.16), females-0.18 (-0.25;-0.11)), prevalent diabetes-0.31 (-0.49;-0.12), hypertension-0.30 (-0.42;-0.18), dyslipidemia-0.24 (-0.40;-0.09), fasting glucose level-0.06 (-0.12;-0.01), HbA1c-0.07 (-0.12;-0.02), triglyceride level-0.09 (-0.14;-0.04), hsCRP-0.12 (-0.17;-0.07), and current smoker versus never smoked-0.50 (-0.67;-0.34). A positive association with peak oxygen saturation was found for cholesterol level 0.05 (0.005; 0.11) and HDL 0.11 (0.06; 0.17). This is the first study showing that post-ischemic skin microvascular peak oxygen saturation is associated with virtually all established cardiovascular risk factors in a population-based middle-aged cohort.
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42. |
- Jungner, Mårten, et al.
(författare)
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Rosuvastatin in Experimental Brain Trauma: Improved Capillary Patency but no Effect on Edema or Cerebral Blood Flow.
- 2013
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 88:Mars,25, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Microvascular dysfunction, characterized by edema formation secondary to increased blood-brain barrier (BBB) permeability and decreased blood flow, contributes to poor outcome following brain trauma. Recent studies have indicated that statins may counteract edema formation following brain trauma but little is known about other circulatory effects of statins in this setting. The objective of this study was to investigate whether statin treatment improves brain microcirculation early after traumatic brain injury, and whether microvascular effects are associated with altered production of nitric oxide and prostacyclin. METHODS: After fluid percussion injury, rats were randomized to intravenous treatment with 20mg/kg of rosuvastatin or vehicle. Brain edema (wet/dry weight), BBB integrity ((51)Cr-EDTA blood to brain transfer), cerebral blood flow ((14)C-iodoantipyrine autoradiography), and number of perfused cortical capillaries (FITC-albumin fluorescence microscopy), were measured at 4 and 24hours. NO and prostacyclin production was estimated from plasma concentration of the degradation products NO2- and NO3- (NOx) and 6-keto-PGF1-alpha, respectively. Sham injured animals were treated with vehicle and analyzed at 4hours. RESULTS: Trauma resulted in brain edema, BBB dysfunction, and reduced cortical blood flow, with no effect of statin treatment. Trauma also induced a reduction in the number of perfused capillaries, which was improved by statin treatment. Statin treatment led to increased NOx levels and reduced mean arterial blood pressure. 6-keto-PGF1-alpha levels tended to increase after trauma, and were significantly reduced by rosuvastatin. CONCLUSIONS: Rosuvastatin treatment may improve microcirculation after traumatic brain injury by preserved patency of cerebral capillaries. This effect is associated with increased NO and reduced prostacyclin production. No effect on brain edema or BBB-barrier integrity was found.
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43. |
- Karbalaie, Abdolamir, 1970-, et al.
(författare)
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Elliptical broken line method for calculating capillary density in nailfold capillaroscopy : Proposal and evaluation
- 2017
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 113, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Nailfold capillaroscopy is a practical method for identifying and obtaining morphological changes in capillaries which might reveal relevant information about diseases and health. Capillaroscopy is harmless, and seems simple and repeatable. However, there is lack of established guidelines and instructions for acquisition as well as the interpretation of the obtained images; which might lead to various ambiguities. In addition, assessment and interpretation of the acquired images are very subjective. In an attempt to overcome some of these problems, in this study a new modified technique for assessment of nailfold capillary density is introduced. The new method is named elliptic broken line (EBL) which is an extension of the two previously known methods by defining clear criteria for finding the apex of capillaries in different scenarios by using a fitted elliptic. A graphical user interface (GUI) is developed for pre-processing, manual assessment of capillary apexes and automatic correction of selected apexes based on 90° rule. Intra- and inter-observer reliability of EBL and corrected EBL is evaluated in this study. Four independent observers familiar with capillaroscopy performed the assessment for 200 nailfold videocapillaroscopy images, form healthy subject and systemic lupus erythematosus patients, in two different sessions. The results show elevation from moderate (ICC = 0.691) and good (ICC = 0.753) agreements to good (ICC = 0.750) and good (ICC = 0.801) for intra- and inter-observer reliability after automatic correction of EBL. This clearly shows the potential of this method to improve the reliability and repeatability of assessment which motivates us for further development of automatic tool for EBL method.
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44. |
- Karbalaie, Abdolamir, 1975-, et al.
(författare)
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Image Enhancement Effect on Inter and Intra-observer Reliability of Nailfold Capillary Assessment
- 2018
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Ingår i: Microvascular Research. - : Elsevier. - 0026-2862 .- 1095-9319.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Nailfold capillaroscopy (NC) is a diagnostic imaging technique that is used to assess the blood capillary network in the nailfold area. NC is routinely used for patients with microcirculation problems, such as systemic sclerosis and other connective tissue diseases. Experts commonly use subjective evaluation as a reference point in images of nailfold video capillaroscopy, so it is important to reduce the inherent ambiguities in human judgment and diagnosis. Image quality is an important factor that affects measurement error and assessment time of NC images.Objective: In this study, a new image enhancement technique was introduced and evaluated subjectively.Methods: In total, 475 nailfold video capillaroscopy images from 18 healthy subjects and 41 systemic lupus erythematosus patients were used. The images were randomly divided into two sets, one each with 275 and 200. Eight independent observers who were familiar with the capillaroscopy technique participated in this study. The set of 275 images was evaluated by three observers with the forced–choice pairwise comparison method. Elliptic broken line (EBL) was used to count the number of capillaries. The intra- and inter-observer reliability of the original and enhanced images was evaluated on 200 images by five observers.Result: Except for eight images, all observers preferred the enhanced images in the visual quality comparison method. The intra-class correlation coefficient (ICC) of intra- and inter-observer reliability increased from 0.76-0.84 to 0.82-0.89, respectively, when using the enhancement method.Conclusion: By improving the image quality, more capillary details will be visible, and an observer can document more details that may not be visible in the original image and can do so more efficiently.
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45. |
- Karlander, Lars-Erik, 1950-, et al.
(författare)
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Acidosis in muscle tissue distal to vascular contusion despite unchanged global blood flow in rats : An uncoupling of microvascular blood flow and metabolism?
- 2005
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 70:1-2, s. 111-115
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Tidskriftsartikel (refereegranskat)abstract
- Studies using a contusion trauma model have shown that the femoral artery of the rat remains patent in 85% despite a severe vessel injury. A significant increase in tissue oxygenation (PtO2) has been found despite only a minor effect on blood flow (<20% decrease) on the muscle surface distal to the injury indicating a disturbed relationship between microvascular blood flow and metabolism. The aim of the present study was to further study the interplay between microvascular blood flow and metabolism within the distal muscle using an ethanol clearance technique (blood flow) in conjunction to the determination of an ischemia marker (lactate) by use of microdialysis. Although skeletal muscle blood flow remained unaltered as assessed by ethanol clearance, skeletal muscle lactate levels increased significantly (P < 0.001) post-trauma in both legs. The increase was initially higher, faster and the increase over time larger in the trauma leg as compared to the control leg (P < 0.001). These findings indicate a systemic effect of the trauma. Further, it suggests a functional impairment of the relationship between microvascular blood flow and/or muscle metabolic processes when the trauma is directed towards the supplying blood vessel. The reason for this anaerobic insult as found in this study compared to the presence of a local increase in PtO2 in the trauma leg as shown in our previous study is suggestive of an microvascular blood flow and tissue metabolism uncoupling. © 2005 Elsevier Inc. All rights reserved.
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46. |
- Keramidas, Michail E., Assistant Professor, et al.
(författare)
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Finger constrictor and thermoperceptual responsiveness to localised cooling following 5 weeks of intermittent regional exposures to moderately augmented transmural vascular pressure
- 2021
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To examine the effects of prolonged intermittent exposures to moderately increased transmural pressure on finger vasoreactivity and thermoperception to localised cooling. Methods: Eleven men completed a 5-week regimen (3 sessions⋅week1; 55 min⋅session1), during which the vasculature in one arm (EXP) was exposed intermittently (10-min exposure: 5-min pause) to increased trans-mural pressure (from +65 mmHg week-1 to +105 mmHg week-5). Before and after the regimen, finger cuta-neous vascular conductance (CVC), temperature (Tavg), and thermoperception (thermal sensation, discomfort and pain) were monitored during a 30-min hand cold (8 ◦C water) provocation trial. The responses of the non-trained hand were examined during an additional cold trial. Results: After the regimen, baseline finger CVC and Tavg were higher in both hands (p ≤0.01). During cooling, neither finger CVC nor Tavg were modified (p >0.05). Yet the magnitude of the cold-induced drop of CVC was augmented in both hands, and to a similar extent (p ≤0.02). The regimen alleviated thermal pain in both hands (p ≤0.02); the sensation of coldness and thermal discomfort were attenuated mainly in the EXP hand (p =0.02). Conclusions: Present findings indicate that iterative local exposures to augmented intravascular pressure do not alter finger vasoreactivity to localised cooling. The pressure training, however, might impair finger basal vasomotor tone, and aggravate the magnitude of constrictor responsiveness to cooling. The pressure training also elicits thermoperceptual desensitisation to noxious thermal stimulus. To large extent, these vascular and perceptual adjustments seem to be transferred to the cutaneous vasculature of the non-trained limb.
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47. |
- Keramidas, Michail E., et al.
(författare)
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Heterogeneous sensitivity of cerebral and muscle tissues to acute normobaric hyperoxia at rest
- 2012
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 84:2, s. 205-210
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to investigate the effects of acute normobaric hyperoxia at rest on cerebral, respiratory and leg muscle oxygenation. Ten healthy men were studied twice in a single-blinded counterbalanced crossover study protocol. On one occasion they breathed air and on the other 100% normobaric O-2 for a 2-hour time period. Oxygenated (Delta[O(2)Hb]), deoxygenated (Delta[HHb]) and total (Delta[tHb]) hemoglobin in the cerebral frontal cortex, and in the intercostal and vastus lateralis muscles were simultaneously monitored with near-infrared spectroscopy. The hyperoxic stimulus promptly increased Delta[O(2)Hb] (similar to 2 mu M) and decreased Delta[HHb] (similar to 3.6 mu M) in the frontal cortex. These cerebral responses were directly and fully countered by resumption of normoxic air breathing. In contrast, Delta[HHb] significantly decreased due to the acute hyperoxic stimulus in both intercostal and vastus lateralis muscles. The temporal changes in muscle oxygenation were slower compared to those in the cerebral area; and they only partially recovered during the 15-min normoxic-recovery period. Acute supplementation of normobaric O-2 at rest influences cerebral, leg and respiratory muscle oxygenation of healthy individuals, but not in the same manner. Namely, the frontal cortex seems to be more sensitive to hyperoxia than are the skeletal muscle regions.
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48. |
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49. |
- Laschke, Matthias, et al.
(författare)
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The Rho-kinase inhibitor Y-27632 inhibits cholestasis-induced platelet interactions in the hepatic microcirculation.
- 2009
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 78, s. 95-99
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Tidskriftsartikel (refereegranskat)abstract
- Bile duct obstruction is associated with hepatic accumulation of leukocytes and liver injury. Emerging data suggest that platelets may play an important role in tissue damage and inflammation. Herein, we characterized the platelet response in cholestatic liver injury and evaluated the role of Rho-kinase signaling. For this purpose, C57BL/6 mice were treated with the Rho-kinase inhibitor Y-27632 (10 mg/kg) and vehicle before undergoing bile duct ligation (BDL) for 12 h. Platelet rolling and adhesion, formation of platelet aggregates as well as microvascular perfusion in the liver were analyzed using intravital fluorescence microscopy. Liver damage was monitored by measuring serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Administration of Y-27632 reduced the BDL-associated increase of ALT and AST by 95% and 89%, respectively. The inhibition of Rho-kinase also reduced cholestasis-induced platelet rolling and adhesion by more than 46% and 73% in postsinusoidal venules and platelet adhesion in sinusoids by 60%. In addition, Y-27632 decreased platelet aggregation in hepatic sinusoids and postsinusoidal venules by 69% and 81%. BDL caused a significant reduction of hepatic microvascular perfusion. Importantly, pretreatment with Y-27632 restored sinusoidal perfusion in cholestatic animals. Our findings demonstrate that Rho-kinase regulates multiple aspects of platelet interaction in the microcirculation of cholestatic animals. Moreover, inhibition of Rho-kinase signaling not only attenuates platelet responses but also maintains microvascular perfusion and protects against hepatocellular injury in cholestasis. Thus, targeting Rho-kinase signaling may be an effective way to protect against platelet-mediated liver injury in obstructive jaundice.
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50. |
- Li, Jie, et al.
(författare)
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Minimally modified LDL upregulates endothelin type B receptors in rat basilar artery
- 2012
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 83:2, s. 178-184
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Tidskriftsartikel (refereegranskat)abstract
- Minimally modified low density lipoprotein (mmLDL) is a well-known risk factor for cerebral vascular diseases and upregulation of endothelin type B (ETB) receptors plays key roles in the pathogenesis. The present study was designed to examine if mmLDL upregulated endothelin ETB receptors in basilar artery and its possible intracellular signaling molecular mechanisms. Rat basilar arteries were cultured for 24 h in the presence of mmLDL with specific inhibitors. The artery contractile responses and receptor expressions of mRNA and protein were investigated using myograph system, real-time PCR and Western blot techniques, respectively. Results showed that ETB receptor agonist, sarafotoxin 6c induced a weak contraction in fresh basilar artery segments. After organ culture the contraction curve mediated by ETB receptor was shifted towards the left with an increased E-max of 88 +/- 6%. The mmLDL 10 mu g/mL further shifted the concentration contractile curves towards the left with an increased E-max of 116 +/- 12%. The organ culture significantly increased ETB receptor mRNA and protein levels from fresh arteries, which was further enhanced by mmLDL The staurosporine (PKC inhibitor), both SB386023 and U0126 (extracellular signal related kinases 1 and 2 inhibitor), and wedelolactone (NF-kappa B inhibitor) almost totally abolished organ culture-increased and mmLDL-increased contraction and expressions of endothelin ETB receptor. SP600125 (C-jun terminal kinase inhibitor) and SB203580 (p38 inhibitor) attenuated both organ cultured-induced and mmLDL-induced upregulation of endothelin ETB receptors. In conclusion, mmLDL upregulates ETB receptors of cerebral basilar artery via the PKC. MAPK and NF-kappa B signal pathways. (C) 2011 Elsevier Inc. All rights reserved.
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