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| 4. |
- 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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| 5. |
- Bergkvist, Max, 1976-, et al.
(författare)
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Vascular Occlusion in a Porcine Flap Model : Effects on Blood Cell Concentration and Oxygenation.
- 2017
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Ingår i: Plastic and Reconstructive Surgery - Global Open. - : Wolters Kluwer. - 2169-7574. ; 5:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Venous congestion in skin flaps is difficult to detect. This study evaluated the ability of tissue viability imaging (TiVi) to measure changes in the concentration of red blood cells (CRBC), oxygenation, and heterogeneity during vascular provocations in a porcine fasciocutaneous flap model.Methods: In 5 pigs, cranial gluteal artery perforator flaps were raised (8 flaps in 5 pigs). The arterial and venous blood flow was monitored with ultrasonic flow probes. CRBC, tissue oxygenation, and heterogeneity in the skin were monitored with TiVi during baseline, 50% and 100% venous occlusion, recovery, 100% arterial occlusion and final recovery, thereby simulating venous and arterial occlusion of a free fasciocutaneous flap. A laser Doppler probe was used as a reference for microvascular perfusion in the flap.Results: During partial and complete venous occlusion, increases in CRBC were seen in different regions of the flap. They were more pronounced in the distal part. During complete arterial occlusion, CRBC decreased in all but the most distal parts of the flap. There were also increases in tissue oxygenation and heterogeneity during venous occlusion.Conclusions: TiVi measures regional changes in CRBC in the skin of the flap during arterial and venous occlusion, as well as an increase in oxygenated hemoglobin during venous occlusion that may be the result of reduced metabolism and impaired delivery of oxygen to the tissue. TiVi may provide a promising method for measuring flap viability because it is hand-held, easy to-use, and provides spatial information on venous congestion.
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| 6. |
- Bergram, Martin, et al.
(författare)
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Low awareness of non-alcoholic fatty liver disease in patients with type 2 diabetes in Swedish Primary Health Care
- 2022
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Ingår i: Scandinavian Journal of Gastroenterology. - : Taylor & Francis Ltd. - 0036-5521 .- 1502-7708. ; 57:1, s. 60-69
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Tidskriftsartikel (refereegranskat)abstract
- Objectives Non-alcoholic fatty liver disease (NAFLD) is more common in patients with type 2 diabetes mellitus (T2DM) compared to individuals without. Recent guidelines recommend screening for NAFLD in patients with T2DM. Our aim was to investigate the prevalence of NAFLD in patients with T2DM in a Swedish primary health care setting, how they are cared for and assess the risk of biochemical signs of advanced fibrosis. Material and methods In this cohort study, patients with T2DM from five primary health care centers were included. Medical records were retrospectively reviewed and living habits, medical history, results of diagnostic imaging and anthropometric and biochemical features were noted in a standardized form. The risk of steatosis and advanced fibrosis was assessed using commonly used algorithms (FLI, HSI, NAFLD-LFS, NAFLD ridge score, FIB-4 and NFS). Results In total 350 patients were included. Diagnostic imaging had been performed in 132 patients and of these, 34 (26%) had steatosis, which was not noted in the medical records in 16 (47%) patients. One patient with steatosis had been referred to a hepatologist. Of assessable patients, 71-97% had a high to intermediate risk of steatosis and 29-65% had an intermediate to high risk of advanced fibrosis according to the algorithms used. Conclusion This study indicates a high prevalence of NAFLD among T2DM patients in Swedish primary care. Patients with known NAFLD were followed up to a very low extent. Using fibrosis algorithms in primary health care would result in many patients needing further assessment in secondary care.
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| 7. |
- Fredriksson, Ingemar, 1980-, et al.
(författare)
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Vasomotion analysis of speed resolved perfusion, oxygen saturation, red blood cell tissue fraction, and vessel diameter : Novel microvascular perspectives
- 2022
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Ingår i: Skin research and technology. - : Wiley-Blackwell Publishing Inc.. - 0909-752X .- 1600-0846. ; 28:1, s. 142-152
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundVasomotion is the spontaneous oscillation in vascular tone in the microcirculation and is believed to be a physiological mechanism facilitating the transport of blood gases and nutrients to and from tissues. So far, Laser Doppler flowmetry has constituted the gold standard for in vivo vasomotion analysis.Materials and methodsWe applied vasomotion analysis to speed-resolved perfusion, oxygen saturation, red blood cell tissue (RBC) tissue fraction, and average vessel diameter from five healthy individuals at rest measured by the newly developed Periflux 6000 EPOS system over 10 minutes. Magnitude scalogram and the time-averaged wavelet spectra were divided into frequency intervals reflecting endothelial, neurogenic, myogenic, respiratory, and cardiac function.ResultsRecurrent high-intensity periods of the myogenic, neurogenic, and endothelial frequency intervals were found. The neurogenic activity was considerably more pronounced for the oxygen saturation, RBC tissue fraction, and vessel diameter signals, than for the perfusion signals. In a correlation analysis we found that changes in perfusion in the myogenic, neurogenic, and endothelial frequency intervals precede changes in the other signals. Furthermore, changes in average vessel diameter were in general negatively correlated to the other signals in the same frequency intervals, indicating the importance of capillary recruitment.ConclusionWe conclude that vasomotion can be observed in signals reflecting speed resolved perfusion, oxygen saturation, RBC tissue fraction, and vessel diameter. The new parameters enable new aspects of the microcirculation to be observed.
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| 8. |
- Hackethal, Johannes, et al.
(författare)
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Microvascular effects of microneedle application
- 2021
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Ingår i: Skin research and technology. - : WILEY. - 0909-752X .- 1600-0846. ; 27, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- Background The efficiency of transdermal drug delivery may be increased by pretreating the skin with microneedles, but distinct effects of microneedles and the microneedle-enhanced delivery of vasoactive drugs on the skin microvasculature are still not well investigated. Materials and Methods In eight healthy human subjects, we measured the microvascular response to microneedle-induced microtraumas in the skin microvasculature using polarized light spectroscopy imaging (Tissue Viability imaging, TiVi). The microvascular response was assessed for up to 48 hours for three microneedle sizes (300 mu m, 500 mu m, and 750 mu m) and for different pressures and application times. Results In our results, microneedle application increased the local red blood cell (RBC) concentration for up to 24 hours dependent on the needle lengths, applied time, and force. Conclusion Optimization of microneedles size, pressure, and application time should be taken into account for future protocols for drug delivery and experimental provocations.
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| 9. |
- Henricson, Joakim, 1977-, et al.
(författare)
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In vivo dose-response analysis to acetylcholine : pharmacodynamic assessment by polarized reflectance spectroscopy
- 2022
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Ingår i: Scientific Reports. - London, United Kingdom : Nature Publishing Group. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Transdermal iontophoresis offers an in vivo alternative to the strain-gauge model for measurement of vascular function but is limited due to lack of technical solutions for outcome assessment. The aims of this study were to, after measurement by polarized reflectance spectroscopy (PRS), use pharmacodynamic dose-response analysis on responses to different concentrations of acetylcholine (ACh); and to examine the effect of three consecutively administered iontophoretic current pulses. The vascular responses in 15 healthy volunteers to iontophorised ACh (5 concentrations, range 0.0001% to 1%, three consecutive pulses of 0.02 mA for 10 min each) were recorded using PRS. Data were fitted to a four-parameter logistic dose response model and compared. Vascular responses were quantifiable by PRS. Similar pharmacodynamic dose response curves could be generated irrespectively of the ACh concentration. Linearly increasing maximum vasodilatory responses were registered with increasing concentration of ACh. A limited linear dose effect of the concentration of ACh was seen between pulses. Polarized reflectance spectroscopy is well suited for measuring vascular responses to iontophoretically administrated ACh. The results of this study support further development of iontophoresis as a method to study vascular function and pharmacological responses in vivo.
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| 10. |
- Henricson, Joakim, 1977-, et al.
(författare)
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Micropuncture closure following high density microarray patch application in healthy subjects
- 2022
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 28:2, s. 305-310
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Tidskriftsartikel (refereegranskat)abstract
- Background The high-density microarray patch (HD-MAP) promises to be a robust vaccination platform with clear advantages for future global societal demands for health care management. The method of action has its base not only in efficient delivery of vaccine but also in the reliable induction of a local innate physical inflammatory response to adjuvant the vaccination process. The application process needs to induce levels of reactivity, which are acceptable to the vaccine, and from which the skin promptly recovers. Materials and methods 1 x 1 cm HD-MAP patches containing 5000, 250-mu m long microprojections were applied to the skin in 12 healthy volunteers. The return of skin barrier function was assessed by transepidermal water loss (TEWL) and reaction to topical histamine challenge. Results Skin barrier recovery by 48 h was confirmed for all HD-MAP sites by recovered resistance to the effects of topical histamine application. Conclusions Our previous observation, that the barrier disruption indicator TEWL returns to normal by 48 h, is supported by this papers demonstration of return of skin resistance to topical histamine challenge in twelve healthy subjects.
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| 11. |
- Henricson, Joakim, et al.
(författare)
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Moisture sensor for exudative wounds : A pilot study
- 2021
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Ingår i: Skin research and technology. - : Wiley. - 0909-752X .- 1600-0846. ; 27:5, s. 918-924
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Tidskriftsartikel (refereegranskat)abstract
- Background Exudative wounds cause discomfort for patients. Introduction of a moisture sensor to dressings could facilitate change of dressings only when needed. The aim of this pilot study was to evaluate the ability of a newly developed moisture sensor to detect moisture in relation to the absorbing capacity of the dressing. Materials and Methods In five patients, with one leg ulcer each, three dressing changes per patient were observed. Interval of dressing change was according to clinical need and healthcare professionals decision. Sensor activation, dressing weight and complications were registered. To investigate the effect of dressing on sensor activation, half of the observations were made without an extra layer of non-woven between the dressing and sensor (Variant A), and half with (Variant B). Results The sensor indicated time for dressing change in six out of fifteen observations. Variants A and B did not differ regarding activation or the timing of the activation. Conclusions The addition of a moisture sensor for facilitating management of exudative wounds is promising. We recommend future larger studies evaluating the potential clinical benefits and risks of the addition of a moisture sensor. We also recommend evaluation of potential home monitoring of wounds by a moisture sensor.
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| 12. |
- 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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| 13. |
- Högstedt, Alexandra, et al.
(författare)
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Effect of N-G-monomethyl l-arginine on microvascular blood flow and glucose metabolism after an oral glucose load
- 2020
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Ingår i: Microcirculation. - : WILEY. - 1073-9688 .- 1549-8719. ; 27:3
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Tidskriftsartikel (refereegranskat)abstract
- Objective The aim of this study was to investigate whether the effects on local blood flow and metabolic changes observed in the skin after an endogenous systemic increase in insulin are mediated by the endothelial nitric oxide pathway, by administering the nitric oxide synthase inhibitor N-G-monomethyl l-arginine using microdialysis. Methods Microdialysis catheters, perfused with N-G-monomethyl l-arginine and with a control solution, were inserted intracutaneously in 12 human subjects, who received an oral glucose load to induce a systemic hyperinsulinemia. During microdialysis, the local blood flow was measured by urea clearance and by laser speckle contrast imaging, and glucose metabolites were measured. Results After oral glucose intake, microvascular blood flow and glucose metabolism were both significantly suppressed in the N-G-monomethyl l-arginine catheter compared to the control catheter (urea clearance: P amp;lt; .006, glucose dialysate concentration: P amp;lt; .035). No significant effect of N-G-monomethyl l-arginine on microvascular blood flow was observed with laser speckle contrast imaging (P = .81). Conclusion Local delivery of N-G-monomethyl l-arginine to the skin by microdialysis reduces microvascular blood flow and glucose delivery in the skin after oral glucose intake, presumably by decreasing local insulin-mediated vasodilation.
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| 14. |
- Iredahl, Fredrik, 1988-
(författare)
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Assessment of microvascular and metabolic responses in the skin
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this project was to develop experimental in vivo models that allow for minimally invasive investigations of responses in the skin to microvascular and metabolic provocations. The cutaneous microvasculature has emerged as a valuable model and been proposed to mirror the microcirculation in other organs. Dysfunction in the cutaneous microcirculation has thus been linked to systemic diseases such as hypertension and diabetes mellitus. Models for investigating skin responses could facilitate the understanding of pathophysiological mechanisms as well as effects of drugs.In the first study, three optical measurement techniques (laser Doppler flowmetry (LDF), laser speckle contrast imaging (LSCI) and tissue viability imaging (TiVi)) were compared against each other and showed differences in their ability to detect microvascular responses to provocations in the skin. TiVi was found more sensitive for measurement of noradrenaline-induced vasoconstriction, while LSCI was more sensitive for measurement of vascular occlusion. In the second study, microvascular responses in the skin to iontophoresis of vasoactive drugs were found to depend on the drug delivery protocol. Perfusion half-life was defined and used to describe the decay in the microvascular response to a drug after iontophoresis. In the third study, the role of nitric oxide (NO) was assessed during iontophoresis of insulin. The results showed a NO-dependent vasodilation in the skin by insulin. In the fourth study the vasoactive and metabolic effects of insulin were studied after both local and endogenous administration. Local delivery of insulin increased skin blood flow, paralleled by increased skin concentrations of interstitial pyruvate and lactate, although no change in glucose concentration was observed. An oral glucose load resulted in an increased insulin concentration in the skin paralleled by an increase in blood flow, as measured using the microdialysis urea clearance technique, although no changes in perfusion was measured by LSCI.The thesis concludes that when studying skin microvascular responses, the choice of measurement technique and the drug delivery protocol has an impact on the measurement results, and should therefore be carefully considered. The thesis also concludes that insulin has metabolic and vasodilatory effects in the skin both when administered locally and as an endogenous response to an oral glucose load. The vasodilatory effect of insulin in the skin is mediated by nitric oxide.
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| 15. |
- Iredahl, Fredrik, et al.
(författare)
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Local Response and Barrier Recovery in Elderly Skin Following the Application of High-Density Microarray Patches
- 2022
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Ingår i: Vaccines. - : MDPI. - 2076-393X. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- The high-density microneedle array patch (HD-MAP) is a promising alternative vaccine delivery system device with broad application in disease, including SARS-CoV-2. Skin reactivity to HD-MAP applications has been extensively studied in young individuals, but not in the >65 years population, a risk group often requiring higher dose vaccines to produce protective immune responses. The primary aims of the present study were to characterise local inflammatory responses and barrier recovery to HD-MAPs in elderly skin. In twelve volunteers aged 69-84 years, HD-MAPs were applied to the forearm and deltoid regions. Measurements of transepidermal water loss (TEWL), dielectric permittivity and erythema were performed before and after HD-MAP application at t = 10 min, 30 min, 48 h, and 7 days. At all sites, TEWL (barrier damage), dielectric permittivity (superficial water);, and erythema measurements rapidly increased after HD-MAP application. After 7 days, the mean measures had recovered toward pre-application values. The fact that the degree and chronology of skin reactivity and recovery after HD-MAP was similar in elderly skin to that previously reported in younger adults suggests that the reactivity basis for physical immune enhancement observed in younger adults will also be achievable in the older population.
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| 16. |
- Iredahl, Fredrik, et al.
(författare)
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Modeling Perfusion Dynamics in the Skin During Iontophoresis of Vasoactive Drugs Using Single-Pulse and Multiple-Pulse Protocols
- 2015
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Ingår i: Microcirculation. - : Informa Healthcare / Wiley: 12 months. - 1073-9688 .- 1549-8719. ; 22:6, s. 446-453
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Tidskriftsartikel (refereegranskat)abstract
- Objective: After iontophoresis of vasoactive drugs into the skin, a decrease in perfusion is commonly observed. We delivered vasoactive drugs by iontophoresis using different delivery protocols to study how these affect this decrease in perfusion as measured using LDF. Methods: We measured skin perfusion during iontophoresis of (ACh), MCh, andNAusing a single pulse or separate pulses at different skin sites, and during repeated delivery of ACh at the same site. Results: Perfusion half-life was 6.1 (5.6-6.6) minutes for ACh and 41 (29-69) minutes for MCh (p less than 0.001). The maximum response with multiple pulses of ACh iontophoresis was lower than with a single pulse, 30 (22-37) PU vs. 43 (36-50) PU, p less than 0.001. Vasoconstriction to NA was more rapid with a single pulse than with multiple pulses. The perfusion half-life of ACh decreased with repeated delivery of ACh at the same site-first 16 (14-18), second 5.9 (5.1-6-9) and third 3.2 (2.9-3.5) minutes, p less than 0.001. Conclusions: The drug delivery protocol affects microvascular responses to iontophoresis, possibly as a result of differences in the dynamics of local drug concentrations. Perfusion half-life may be used as a measure to quantify the rate of perfusion recovery after iontophoresis of vasoactive drugs.
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| 17. |
- Iredahl, Fredrik, et al.
(författare)
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Non-Invasive Measurement of Skin Microvascular Response during Pharmacological and Physiological Provocations
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 10:8, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Microvascular changes in the skin due to pharmacological and physiological provocations can be used as a marker for vascular function. While laser Doppler flowmetry (LDF) has been used extensively for measurement of skin microvascular responses, Laser Speckle Contrast Imaging (LSCI) and Tissue Viability Imaging (TiVi) are novel imaging techniques. TiVi measures red blood cell concentration, while LDF and LSCI measure perfusion. Therefore, the aim of this study was to compare responses to provocations in the skin using these different techniques. Method Changes in skin microcirculation were measured in healthy subjects during (1) iontophoresis of sodium nitroprusside (SNP) and noradrenaline (NA), (2) local heating and (3) post-occlusive reactive hyperemia (PORH) using LDF, LSCI and TiVi. Results Iontophoresis of SNP increased perfusion (LSCI: baseline 40.9 +/- 6.2 PU; 10-min 100 +/- 25 PU; pless than0.001) and RBC concentration (TiVi: baseline 119 +/- 18; 10-min 150 +/- 41 AU; p = 0.011). No change in perfusion (LSCI) was observed after iontophoresis of NA (baseline 38.0 +/- 4.4 PU; 10-min 38.9 +/- 5.0 PU; p = 0.64), while RBC concentration decreased (TiVi: baseline 59.6 +/- 11.8 AU; 10-min 54.4 +/- 13.3 AU; p = 0.021). Local heating increased perfusion (LDF: baseline 8.8 +/- 3.6 PU; max 112 +/- 55 PU; pless than0.001, LSCI: baseline 50.8 +/- 8.0 PU; max 151 +/- 22 PU; pless than0.001) and RBC concentration (TiVi: baseline 49.2 +/- 32.9 AU; max 99.3 +/- 28.3 AU; pless than0.001). After 5 minutes of forearm occlusion with prior exsanguination, a decrease was seen in perfusion (LDF: p = 0.027; LSCI: pless than0.001) and in RBC concentration (p = 0.045). Only LSCI showed a significant decrease in perfusion after 5 minutes of occlusion without prior exsanguination (pless than0.001). Coefficients of variation were lower for LSCI and TiVi compared to LDF for most responses. Conclusion LSCI is more sensitive than TiVi for measuring microvascular changes during SNP-induced vasodilatation and forearm occlusion. TiVi is more sensitive to noradrenaline-induced vasoconstriction. LSCI and TiVi show lower inter-subject variability than LDF. These findings are important to consider when choosing measurement techniques for studying skin microvascular responses.
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| 18. |
- Iredahl, Fredrik, et al.
(författare)
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Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load
- 2016
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Ingår i: Microcirculation. - : Wiley-Blackwell. - 1073-9688 .- 1549-8719. ; 23:7, s. 597-605
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Insulin causes capillary recruitment in muscle and adipose tissue, but the metabolic and microvascular effects of insulin in the skin have not been studied in detail. The aim of this study was to measure glucose metabolism and microvascular blood flow in the skin during local insulin delivery and after an oral glucose load.METHODS: Microdialysis catheters were inserted intracutanously in human subjects. In eight subjects two microdialysis catheters were inserted, one perfused with insulin and one with control solution. First the local effects of insulin was studied, followed by a systemic provocation by an oral glucose load. Additionally, as control experiment, six subjects did not recieve local delivery of insulin or the oral glucose load. During microdialysis the local blood flow was measured by urea clearance and by laser speckle contrast imaging (LSCI).RESULTS: Within 15 minutes of local insulin delivery, microvascular blood flow in the skin increased (urea clearance: P=.047, LSCI: P=.002) paralleled by increases in pyruvate (P=.01) and lactate (P=.04), indicating an increase in glucose uptake. An oral glucose load increased urea clearance from the catheters, indicating an increase in skin perfusion, although no perfusion changes were detected with LSCI. The concentration of glucose, pyruvate and lactate increased in the skin after the oral glucose load.CONCLUSION: Insulin has metabolic and vasodilatory effects in the skin both when given locally and after systemic delivery through an oral glucose load.
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| 19. |
- Iredahl, Fredrik, et al.
(författare)
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The Microvascular Response to Transdermal Iontophoresis of Insulin is Mediated by Nitric Oxide
- 2013
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Ingår i: Microcirculation. - : WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA. - 1073-9688 .- 1549-8719. ; 20:8, s. 717-723
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveInsulin has direct effects on blood flow in various tissues, most likely due to endothelial NO production. We investigated whether insulin delivered to the skin by iontophoresis increases microvascular perfusion and whether this effect is partly or completely mediated by the release of NO. MethodsIn healthy subjects, regular insulin and monomeric insulin were delivered to the skin by cathodal iontophoresis. The skin was pretreated either with L-NAME or control solution (PBS) using anodal iontophoresis. Microvascular responses were measured using laser Doppler flowmetry. ResultsA dose-dependent increase in perfusion was observed during iontophoresis of regular and monomeric insulin. The maximum perfusion was significantly elevated compared with control after PBS (regular insulin 53.6 (12.7-95.6) PU vs. 4.2 (3.4-4.8) PU, p = 0.002; monomeric insulin 32.6 (8.9-92.6) PU vs. 5.9 (3.4-56.0) PU, p = 0.03). The microvascular response to insulin was abolished after L-NAME (regular insulin: 25.6 (11.6-54.4) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.15; monomeric insulin 10.9 (5.4-56.8) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.22). ConclusionsThe main finding is that iontophoresis of insulin induces a dose-dependent vasodilation in the skin, which could be suppressed after pretreatment with a NO synthase inhibitor. This suggests that vasodilation in the skin after iontophoresis of insulin is mediated by the NO pathway.
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| 20. |
- Koppner, Jenny, et al.
(författare)
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Factors affecting self-perceived mental health in the general older population during the COVID-19 pandemic: a cross-sectional study
- 2024
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Ingår i: BMC Public Health. - : BMC. - 1471-2458. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Mental health problems among older people are large public health concerns but often go unrecognized and undertreated. During COVID - 19 several restrictions regarding social contacts were launched, primarily for the old. The objective of this study is to investigate which factors that had the main negative affect on mental health in the older population during the pandemic. Method A cross-sectional cohort study set in Swedish primary care during the pandemic years 2021-2022. The population constitutes of 70-80-years-old, N = 260. Instruments used are Geriatric depression scale 20 (GDS20); Hospital anxiety and depression scale (HADS), and Perceived stress scale 10 (PSS10). Sociodemography and risk factors are explored. Outcome measures are factors independently associated with decreased mental health. Analyses were performed for the group as a whole and with logistic regression models comparing individuals who stated they were mentally affected by the pandemic to individuals who stated they were not. Results Participants who stated they were mentally affected by the COVID - 19 pandemic reported significantly higher levels of anxiety (p < 0.001), depression (p < 0.001), and stress (p = 0.026) compared to those who stated they were not mentally affected. Explanatory regression models of up to 50% showed that following factors were prominent among individuals who reported a decline in their mental health due to the COVID - 19 pandemic (n = 24); impaired social life (OR 20.29, p < 0.001, CI 4.53-90.81), change in physical activity (OR 5.28, p = 0.01, CI 1.49-18.72), perceived family situation (OR 31.90, p = 0,007, CI 2,53-402.42), mild/moderate and high anxiety (OR 4.94, p = 0.034, CI 1.13-21.60, OR 7.96, p = 0.035, CI 1.16-54.53 respectively), and female gender (OR 6.52, p = 0.029, CI 1.22-34.92). Conclusion Anxiety, family situation, social life and change in physical activity were the main factors influencing the 70-80-years-old's self-perceived mental health during the COVID - 19 pandemic. Long-term effects of social restrictions on mental health in the older population need to be further investigated.
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| 21. |
- Mirdell, Robin, et al.
(författare)
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Microvascular blood flow in scalds in children and its relation to duration of wound healing: A study using laser speckle contrast imaging
- 2016
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Ingår i: Burns. - : ELSEVIER SCI LTD. - 0305-4179 .- 1879-1409. ; 42:3, s. 648-654
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Tidskriftsartikel (refereegranskat)abstract
- Background: Microvascular perfusion changes in scalds in children during the first weeks after injury is related to the outcome of healing, and measurements of perfusion, based on laser Doppler imaging, have been used successfully to predict the need for excision and grafting. However, the day-to-day changes in perfusion during the first weeks after injury have not to our knowledge been studied in detail. The aim of this study, based on a conservative treatment model where excision and grafting decisions were delayed to day 14 after injury, was to measure changes in perfusion in scalds using laser speckle contrast imaging (LSCI) during the first three weeks after injury. Methods: We measured perfusion with LSCI in 34 patients at regular intervals between 6 h after injury until complete reepithelialization or surgery. Duration of healing was defined as the time to complete reepithelialization. Results: Less perfusion, between 6 and 96 h after injury, was associated with longer duration of healing with the strongest association occurring between 72 and 96 h. Burns that healed within 14 days had relatively high initial perfusion, followed by a peak and subsequent slow decrease. Both the maximum perfusion and the time-to-peak were dependent on the severity of the burn. Burns that needed excision and grafting had less initial perfusion and a gradual reduction over time. Conclusion: The perfusion in scalds in children shows characteristic patterns during the first weeks after injury depending on the duration of wound healing, the greatest difference between wounds of different severity being on the 4th day. Perfusion should therefore preferably be measured on the fourth day if it is to be used in the assessment of burn depth. (c) 2015 Elsevier Ltd and ISBI. All rights reserved.
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| 22. |
- Nasr, Patrik, et al.
(författare)
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Evaluating the prevalence and severity of NAFLD in primary care: the EPSONIP study protocol
- 2021
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Ingår i: BMC Gastroenterology. - : BMC. - 1471-230X. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundNon-alcoholic fatty liver disease (NAFLD) affects 20-30% of the general adult population. NAFLD patients with type 2 diabetes mellitus (T2DM) are at an increased risk of advanced fibrosis, which puts them at risk of cardiovascular complications, hepatocellular carcinoma, or liver failure. Liver biopsy is the gold standard for assessing hepatic fibrosis. However, its utility is inherently limited. Consequently, the prevalence and characteristics of T2DM patients with advanced fibrosis are unknown. Therefore, the purpose of the current study is to evaluate the prevalence and severity of NAFLD in patients with T2DM by recruiting participants from primary care, using the latest imaging modalities, to collect a cohort of well phenotyped patients.MethodsWe will prospectively recruit 400 patients with T2DM using biomarkers to assess their status. Specifically, we will evaluate liver fat content using magnetic resonance imaging (MRI); hepatic fibrosis using MR elastography and vibration-controlled transient elastography; muscle composition and body fat distribution using water-fat separated whole body MRI; and cardiac function, structure, and tissue characteristics, using cardiovascular MRI.DiscussionWe expect that the study will uncover potential mechanisms of advanced hepatic fibrosis in NAFLD and T2DM and equip the clinician with better diagnostic tools for the care of T2DM patients with NAFLD.Trial registration: Clinicaltrials.gov, identifier NCT03864510. Registered 6 March 2019, https://clinicaltrials.gov/ct2/show/NCT03864510.
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| 23. |
- Samils, Linda, et al.
(författare)
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Workload and sex effects in comprehensive assessment of cutaneous microcirculation
- 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
- Introduction: Workload and sex-related differences have been proposed as factors of importance when evaluating the microcirculation. Simultaneous assessments with diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) enable a comprehensive evaluation of the microcirculation. The aim of the study was to compare the response between sexes in the microcirculatory parameters red blood cell (RBC) tissue fraction, RBC oxygen saturation, average vessel diameter, and speed-resolved perfusion during baseline, cycling, and recovery, respectively.Methods: In 24 healthy participants (aged 20 to 30 years, 12 females), cutaneous microcirculation was assessed by LDF and DRS at baseline, during a workload generated by cycling at 75 to 80 % of maximal age-predicted heart rate, and recovery, respectively.Results: Females had significantly lower RBC tissue fraction and total perfusion in forearm skin microcirculation at all phases (baseline, workload, and recovery). All microvascular parameters increased significantly during cycling, most evident in RBC oxygen saturation (34 % increase on average) and perfusion (9-fold increase in total perfusion). For perfusion, the highest speeds (>10 mm/s) increased by a factor of 31, whereas the lowest speeds (<1 mm/s) increased by a factor of 2.Conclusion: Compared to a resting state, all studied microcirculation measures increased during cycling. For perfusion, this was mainly due to increased speed, and only to a minor extent due to increased RBC tissue fraction. Skin microcirculatory differences between sexes were seen in RBC concentration and total perfusion.
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| 24. |
- Zötterman, Johan, et al.
(författare)
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Monitoring of partial and full venous outflow obstruction in a porcine flap model using laser speckle contrast imaging
- 2016
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Ingår i: Journal of Plastic, Reconstructive & Aesthetic Surgery. - : ELSEVIER SCI LTD. - 1748-6815 .- 1878-0539. ; 69:7, s. 936-943
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Tidskriftsartikel (refereegranskat)abstract
- Background: In microsurgery, there is a demand for more reliable methods of postoperative monitoring of free flaps, especially with regard to tissue-threatening obstructions of the feeding arteries and draining veins. In this study, we evaluated laser speckle contrast imaging (LSCI) and laser Doppler flowmetry (LDF) to assess their possibilities to detect partial and full venous outflow obstruction, as well as full arterial occlusion, in a porcine flap model. Methods: Cranial gluteal artery perforator flaps (CGAPs) were raised, and arterial and venous blood flow to and from the flaps was monitored using ultrasonic flow probes. The venous flow was altered with an inflatable cuff to simulate partial and full (50% and 100%) venous obstruction, and arterial flow was completely obstructed using clamps. The flap microcirculation was monitored using LSCI and LDF. Results: Both LDF and the LSCI detected significant changes in flap perfusion. After partial (50%) venous occlusion, perfusion decreased from baseline, LSCI: 63.5 +/- 12.9 PU (p = 0.01), LDF 31.3 +/- 15.7 (p = 0.64). After 100% venous occlusion, a further decrease in perfusion was observed: LSCI 54.6 +/- 14.2 PU (p amp;lt; 0.001) and LDF 16.7 +/- 12.8 PU (p amp;lt; 0.001). After release of the venous cuff, LSCI detected a return of the perfusion to a level slightly, but not significantly, below the baseline level 70.1 +/- 11.5 PU (p=0.39), while the LDF signal returned to a level not significant from the baseline 36.1 +/- 17.9 PU (p amp;gt; 0.99). Perfusion during 100% arterial occlusion decreased significantly as measured with both methods, LSCI: 48.3 +/- 7.7 (PU, pamp;lt;0.001) and LDF: 8.5 +/- 4.0 PU (pamp;lt;0.001). During 50% and 100% venous occlusion, LSCI showed a 20% and 26% inter-subject variability (CV%), respectively, compared to 50% and 77% for LDF. Conclusions: LSCI offers sensitive and reproducible measurements of flap microcirculation and seems more reliable in detecting decreases in blood perfusion caused by venous obstruction. It also allows for perfusion measurements in a relatively large area of flap tissue. This may be useful in identifying areas of the flap with compromised microcirculation during and after surgery. (C) 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
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