| 1. |
- Barbu, Andreea, et al.
(författare)
-
The use of hydrogen gas clearance for blood flow measurements in single endogenous and transplanted pancreatic islets
- 2015
-
Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 97, s. 124-129
-
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.
|
|
| 2. |
- Bergkvist, Max, et al.
(författare)
-
Assessment of microcirculation of the skin using Tissue Viability Imaging: A promising technique for detecting venous stasis in the skin
- 2015
-
Ingår i: Microvascular Research. - : Elsevier. - 0026-2862 .- 1095-9319. ; 101, s. 20-25
-
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.
|
|
| 3. |
- Bunke, Josefine, et al.
(författare)
-
Extended-wavelength diffuse reflectance spectroscopy for a comprehensive view of blood perfusion and tissue response in human forearm skin
- 2019
-
Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 124, s. 1-5
-
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.
|
|
| 4. |
- Dinsdale, Graham, et al.
(författare)
-
Intra-and inter-observer reliability of nailfold videocapillaroscopy - A possible outcome measure for systemic sclerosis-related microangiopathy
- 2017
-
Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 112, s. 1-6
-
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.
|
|
| 5. |
- Elawa, Sherif, et al.
(författare)
-
The microvascular response in the skin to topical application of methyl nicotinate : Effect of concentration and variation between skin sites
- 2019
-
Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 124, s. 54-60
-
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.
|
|
| 6. |
- Emrani, Zahra, et al.
(författare)
-
Capillary density : An important parameter in nailfold capillaroscopy
- 2017
-
Ingår i: Microvascular Research. - Netherland : Elsevier. - 0026-2862 .- 1095-9319. ; 109, s. 7-18
-
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.
|
|
| 7. |
- Fatemi, Alimohammad, et al.
(författare)
-
Nailfold microvascular changes in patients with systemic lupus erythematosus and their associative factors
- 2019
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 126
-
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.
|
|
| 8. |
- Ingegnoli, Francesca, et al.
(författare)
-
A comparison between nailfold capillaroscopy patterns in adulthood in juvenile and adult-onset systemic sclerosis: A EUSTAR exploratory study
- 2015
-
Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 102, s. 19-24
-
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.
|
|
| 9. |
- Jonasson, Hanna, et al.
(författare)
-
Oxygen saturation, red blood cell tissue fraction and speed resolved perfusion — A new optical method for microcirculatory assessment
- 2015
-
Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 102, s. 70-77
-
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.
|
|
| 10. |
- Karbalaie, Abdolamir, 1970-, et al.
(författare)
-
Elliptical broken line method for calculating capillary density in nailfold capillaroscopy : Proposal and evaluation
- 2017
-
Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 113, s. 1-8
-
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.
|
|
