1. |
- Awan, Z A, et al.
(author)
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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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In: MICROVASCULAR RESEARCH. - : Elsevier Science B.V., Amsterdam. - 0026-2862. ; 81:3, s. 245-251
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Journal article (peer-reviewed)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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2. |
- Bansch, Peter, et al.
(author)
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Effect of charge on microvascular permeability in early experimental sepsis in the rat.
- 2011
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In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 82, s. 339-345
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Journal article (peer-reviewed)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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3. |
- Farnebo, Simon, et al.
(author)
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Hyperaemic changes in forearm skin perfusion and RBC concentration after increasing occlusion times
- 2010
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In: MICROVASCULAR RESEARCH. - : Elsevier Science B.V., Amsterdam. - 0026-2862. ; 80:3, s. 412-416
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Journal article (peer-reviewed)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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4. |
- Ingegnoli, Francesca, et al.
(author)
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Nailfold capillaroscopy in systemic sclerosis: Data from the EULAR scleroderma trials and research (EUSTAR) database
- 2013
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In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 89, s. 122-128
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Journal article (peer-reviewed)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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5. |
- Jungner, Mårten, et al.
(author)
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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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In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 88:Mars,25, s. 48-55
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Journal article (peer-reviewed)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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6. |
- Keramidas, Michail E., et al.
(author)
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Heterogeneous sensitivity of cerebral and muscle tissues to acute normobaric hyperoxia at rest
- 2012
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In: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 84:2, s. 205-210
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Journal article (peer-reviewed)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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7. |
- Li, Jie, et al.
(author)
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Minimally modified LDL upregulates endothelin type B receptors in rat basilar artery
- 2012
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In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 83:2, s. 178-184
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Journal article (peer-reviewed)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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8. |
- Nilsson, Jan, et al.
(author)
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Microcirculation changes during liver resection - A clinical study.
- 2014
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In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 94:May 16, s. 47-51
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Journal article (peer-reviewed)abstract
- In this study we aimed to evaluate effects of liver resection on hepatic microcirculation. In addition we wanted to study if histological liver damage could be detected intra-operatively.
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9. |
- Tesselaar, Erik, et al.
(author)
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Transdermal iontophoresis as an in-vivo technique for studying microvascular physiology
- 2011
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In: MICROVASCULAR RESEARCH. - : Elsevier Science B.V., Amsterdam. - 0026-2862. ; 81:1, s. 88-96
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Journal article (peer-reviewed)abstract
- Assessment of microvascular function is of major importance in understanding the physiology of the vasculature and in investigating the vascular effects of pathological conditions. Transdermal iontophoresis can be used to non-invasively introduce vasoactive drugs into the skin. The response of the local cutaneous microvasculature to these drugs can be measured by methods such as laser Doppler flowmetry. Although the technique has been used for over two decades, there are still important methodological issues to be resolved. This review describes the technique of iontophoresis as well as its development during recent years, while focusing on how iontophoresis can be used as an in-vivo model for studying physiologic mechanisms and on the analysis and interpretation of dose-response data.
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