Laser Speckle Contrast Analysis Research Articles

Relationship between peripheral and intracoronary blood flow in patients with angina and non-obstructive coronary arteries.

Background: Coronary vasomotor dysfunction, an important underlying cause of angina and non-obstructive coronary arteries (ANOCA), encompassing coronary vasospasm, coronary endothelial dysfunction and/or coronary microvascular dysfunction, is clinically assessed by invasive coronary function testing (ICFT). As ICFT imposes a high burden on patients and carries risks, developing non-invasive alternatives is important. We evaluated whether coronary vasomotor dysfunction is a component of systemic microvascular endothelial and smooth muscle dysfunction, and can be detected using laser speckle contrast analysis (LASCA). Methods: Forty-three consecutive ANOCA patients underwent ICFT, with intracoronary acetylcholine, adenosine, and flow measurements, to assess coronary vasomotor dysfunction. Cutaneous microvascular function was assessed using LASCA, combined with vasodilators acetylcholine, sodium-nitroprusside and insulin and using EndoPAT, by measuring the reactive hyperemia index (RHI). Results: Of the 43 included ANOCA patients (79% women, 59±9 years), 38 patients had coronary vasomotor dysfunction, including 28 with coronary vasospasm, 26 with coronary endothelial dysfunction and 18 with coronary microvascular dysfunction, with overlapping endotypes. Patients with and without coronary vasomotor dysfunction had similar peripheral flow responses to acetylcholine, insulin, and RHI. In contrast, coronary vasomotor dysfunction was associated with lower peripheral flow responses to sodium-nitroprusside (p<0.001). An absolute flow response to sodium-nitroprusside of 83.95APU resulted in 86.1% sensitivity and 80.0% specificity for coronary vasomotor dysfunction (area under the ROC curve: 0.883; p=0.006). Conclusions: This study provides evidence of a systemic vascular smooth muscle dysfunction in ANOCA patients with coronary vasomotor dysfunction, and diagnostic value of peripheral microvascular function testing as non-invasive tool for detecting coronary vasomotor dysfunction.

Skin Microvascular Dysfunction in Type 2 Diabetes Mellitus Using Laser Speckle Contrast Analysis and Association with Carotid Intima-Media Thickness.

Background: It is established that diabetes mellitus (DM) is characterized by increased cardiovascular risk associated with subclinical atherosclerosis as well as microvascular alterations. Laser speckle contrast analysis (LASCA) is an innovative, non-invasive method for assessing skin microvascular function. Objectives: We sought to assess skin microvascular function in patients with type 2 DM and matched controls. Methods: Consecutive patients with DM and individuals matched for age, sex and BMI were included in the study. Skin microvascular perfusion was assessed, using LASCA, during baseline, a 5 min occlusion period and a 5 min reperfusion period. Carotid intima-media thickness (cIMT) was measured as a surrogate marker of macrocirculation. Results: In total, 18 patients with DM and 22 in the control group were enrolled. No statistically significant differences were observed in baseline flux, peak flux and percentage decrease during arterial occlusion. During reperfusion, individuals with DM exhibited a smaller peak magnitude compared to controls (147.0 ± 64.7% vs. 189.4 ± 46.0%, respectively; p < 0.05). Moreover, cIMT was higher in patients with DM compared to controls (0.68 ± 0.09 mm vs. 0.60 ± 0.08 mm, respectively, p < 0.01) and was negatively correlated with skin microvascular reactivity in the univariate analysis. In the multivariate analysis, glucose and office systolic blood pressure levels remained significant predictors of microvascular reactivity. Conclusions: Our study shows that patients with type 2 DM exhibit impaired skin microvascular function compared to controls. Furthermore, glucose levels and blood pressure play a key role in microvascular dysfunction. However, additional studies are needed to address the clinical significance of early microvascular changes in DM.

A pilot study using the LASCA technique to analyze stress using heart rate variability.

In the quest to uncover biological cues that help explain organic changes brought on by an external stimulus, like stress, new technologies have become necessary. The Laser Speckle Contrast Analysis (LASCA) approach is one of these technologies that may be used to analyze biological data, including respiratory rate (RR) intervals, and then use the results to determine heart rate variability (HRV Thus, to evaluate the stress brought on by physical activity, this study used the LASCA approach. A stress induction procedure involving physical exertion was employed, and the results were compared to other established techniques (cortisol analysis and ECG signal) to verify the LASCA methodology as a tool for measuring HRV and stress. The study sample comprised 27 willing participants. The technique involving LASCA allowed for the non-invasive (non-contact) acquisition of HRV and the study of stress. Furthermore, it made it possible to gather pertinent data, such as recognizing modifications to the thermoregulation, peripheral vasomotor tonus, and renin-angiotensin-aldosterone systems that were brought on by elevated stress and, as a result, variations in HRV readings.

Long-Term Data on Efficacy and Safety of Selexipag for Digital Systemic Sclerosis Vasculopathy.

Raynaud phenomenon (RP) and digital ulcers (DUs) are the main signs of digital vasculopathy in systemic sclerosis (SSc). Selexipag is an oral prostacyclin agonist approved for SSc-related pulmonary arterial hypertension. Following our previous preliminary short-course report, we herein present long-term data on selexipag safety and efficacy in the treatment of SSc digital vasculopathy. Selexipag was administered to patients with SSc with severe digital vasculopathy refractory or with contraindication to all other vasoactive therapies. Each subject was assessed at baseline and after 3, 6, and 12 months. Clinical outcomes related to RP and DUs were evaluated along with modified Rodnan skin score of the fingers. Digital perfusion was assessed by laser speckle contrast analysis (LASCA). Nailfold videocapillaroscopy (NVC) was also performed. Eight patients with SSc (63% female, mean age 50.1 years) received selexipag. After 12 months of treatment, RP was reported to significantly decrease in the number of daily episodes and mean duration (P < 0.001 and P = 0.01, respectively). All patients achieved a complete healing of their DUs (P = 0.03) within 6 months. A progressive reduction of fingers skin score was observed (P = 0.03). No structural changes of capillaries were noted on NVC. Conversely, LASCA revealed an important increase in total digital perfusion (P = 0.004) despite seasonal variability. The safety profile was consistent with that reported in the literature. We observed a sustained efficacy of selexipag on SSc digital vasculopathy during 1 year of administration. Our promising results encourage the design of a new randomized controlled trial to evaluate the effect of selexipag on SSc digital vasculopathy.

Accumulation of Microvascular Target Organ Damage in Systemic Lupus Erythematosus Patients Is Associated with Increased Cardiovascular Risk.

Background: Systemic lupus erythematosus (SLE) is a prototype autoimmune disease associated with increased cardiovascular (CV) burden. Besides increased arterial stiffness and subclinical atherosclerosis, microvascular dysfunction is considered an important component in the pathophysiology of CV disease. However, there is a lack of data regarding the effect of multiple target organ damage (TOD) on CV health. Objectives: This study aimed to evaluate (i) the presence of microvascular changes in SLE in various vascular beds, (ii) the possible associations between the accumulation of microvascular TOD and CV risk and (iii) whether Galectin-3 represents a predictor of combined microvascular TOD. Methods: Participants underwent (i) evaluation of skin microvascular perfusion (laser speckle contrast analysis), (ii) fundoscopy (non-mydriatic fundus camera), (iii) indirect assessment of myocardial perfusion (subendocardial viability ratio) and (iv) determination of urine albumin-to-creatinine ratio (UACR). CV risk was calculated using the QResearch Risk Estimator version 3 (QRISK3). Serum Galectin-3 levels were determined. Results: Forty-seven SLE patients and fifty controls were studied. SLE patients demonstrated impaired skin microvascular reactivity (160.2 ± 41.0 vs. 203.6 ± 40.1%), retinal arteriolar narrowing (88.1 ± 11.1 vs. 94.6 ± 13.5 μm) and higher UACR levels compared to controls. Furthermore, SLE individuals had significantly higher Galectin-3 levels [21.5(6.1) vs. 6.6(6.6) ng/dL], QRISK3 scores [7.0(8.6) vs. 1.3(3.6)%] and a greater chance for microvascular dysfunction. In the SLE group, patients with multiple TOD exhibited higher QRISK3. In the multivariate analysis, the accumulation of TOD correlated with disease activity and Galectin-3 (p < 0.05). Conclusions: Our study showed for the first time that SLE patients exhibit a greater number of cases of TOD. The accumulation of TOD was associated with increased CV risk. Clinicians dealing with SLE should be aware and seek microvascular alterations.

Role of IL33 in chronic inflammation and microvascular damage as a reflection of organ damage on a cohort of patients with acromegaly

AimAcromegaly is a rare chronic disease, caused by the over-secretion of growth hormone (GH), that creates a pro-inflammatory state, but the exact mechanisms by which GH or insulin-like growth factor 1 (IGF-1) act on inflammatory cells are not fully understood. Aim of the study was to evaluate Interleukin-33 (IL33) and the skin perfusion of hands in patients with acromegaly (AP) and healthy controls (HC).MethodsIL33 have been assessed in 40 AP and 40 HC. IL 33 was determined and skin perfusion of hands was assessed by laser speckle contrast analysis (LASCA) in both populations.ResultsIL33 was significantly higher in AP compared to HC [45.72 pg/ml (IQR 28.74–60.86) vs 14 pg/ml (IQR 6.5535); p < 0.05]. At LASCA, peripheral blood perfusion (PBP) was significantly lower in AP compared to HC [53.39 pU (IQR 40.94–65.44) vs 87 pU (IQR 80–98) p < 0.001]. The median values of ROI1, ROI2 and ROI3 were significantly lower in AP compared to HC [97.32 pU (IQR 50.89–121.69) vs 131 pU (IQR 108–135); p < 0.001], [58.68 pU (IQR 37.72–84.92) vs 83 pU (IQR 70–89), p < 0.05] and HC [52.16 (34.47–73.78) vs 85 (78–98), p < 0.001], respectively. The proximal–distal gradient (PDG) was observed in 18 of 40 (45%) AP.ConclusionSerum IL33 is higher in AP compared to HC; conversely a reduction of PBP of hands was present in AP compared to HC, probably due to endothelial dysfunction, strictly dependent on acromegaly and are not influenced by the choice of treatment.

Peripheral and ocular microvascular alterations in systemic sclerosis: observations from capillaroscopic assessments, perfusion peripheral analysis, and optical coherence tomography angiography.

To investigate the correlations between finger microvascular morphology and function in patients with systemic sclerosis (SSc) and the status of ocular microcirculation, as detected by nailfold videocapillaroscopy (NVC), laser speckle contrast analysis (LASCA), and optical coherence tomography angiography (OCTA). The enrollment included 32 SSc patients, classified according to the 2013 ACR/EULAR criteria, and 27 sex- and age-matched healthy controls. The participants underwent comprehensive rheumatological and ophthalmological examinations, as well as NVC, LASCA, and OCTA analysis on the same day at a single center from March to October 2022. SSc patients receiving intravenous prostanoids cycles were assessed at least 1month after infusion. Statistical analysis was conducted using Stata® 15.1. Significant direct correlations were observed between the mean capillary number (at NVC) and the mean perfusion of fingers (at LASCA) with the retinal and choroidal perfusion (at OCTA) (all p < 0.05). In addition, a significantly reduced retinal and choroidal perfusion was detected in SSc patients vs controls (all p < 0.05). Interestingly, diffuse cutaneous SSc (dcSSc) patients exhibited a lower choroidal perfusion (p = 0.03) but an increased choroidal thickness (CT) than limited cutaneous SSc patients (p < 0.001). CT was increased also in patients with positive Scl70 antibodies and with a history of digital ulcers directly correlating with disease duration (r = 0.67, p = 0.001). Finally, the combination of LASCA and OCTA parameters showed a significant discrimination capacity between SSc patients and controls, with an area under the curve of 0.80 [95% CI (0.74, 0.87)]. Peripheral microvascular damage is correlated with impaired ocular microcirculation in SSc. The increased choroidal thickness observed in dcSSc may be related to local sub-endothelial extracellular matrix deposition. The combined analysis of choroidal and fingertip perfusion offers preliminary insights that may complement traditional diagnostic methods for SSc.

Multiexposure laser speckle contrast analysis system calibration limited by perfusion-dependent scattering on the skin.

Application of multiexposure speckle contrast imaging (MESI) methods for perfusion measurements can correct for the contribution of static scattering of the skin, at the expense of reduced temporal resolution as compared to classical single-exposure methods. Persistence of tissue scattering properties during the measurements could allow for an initial calibration and enhancement of the temporal resolution of the measurements. We aim to study the influence of the perfusion on the light scattering of the forearm skin and to use the obtained data for the enhancement of the temporal resolution. A wide range of skin perfusion states was induced while monitoring the changes in the dynamic range of the exposure-dependent contrast. Different measurement and evaluation methods were tested based on an initial MESI calibration followed by image recording with reduced number of exposure time values. The changes in the skin perfusion can alter not only the contribution of the static scattering to the speckle images but also the short-exposure time contrast limit. The perfusion-dependent scattering of the skin can invalidate the precalibrations (e.g., calibration) characterizing the combination of the given tissue and the measurement system.

Validation of Skin Perfusion Monitoring by Imaging PPG versus Laser Speckle Imaging

Abstract Assessment of skin perfusion can reveal signs of deterioration and help to prevent critical states. Commonly applied clinical tests to capture skin perfusion are subjective and often hard to quantify. Laser speckle contrast analysis (LASCA) is a technique that can capture skin perfusion at high spatial and temporal resolution. LASCA requires, however, a complex setting and is not suited for monitoring under clinical conditions. Imaging photoplethysmography (iPPG) might be an easy to use alternative. However, direct comparisons of LASCA and iPPG, and thus proves of iPPG’s capabilities to capture skin microperfusion, are rare. In this work, we compare the longitudinal development of the amplitude of green channel and near-infrared iPPG and LASCA after application of a hyperemic test. Our results show statistically significant increases in amplitude over time in all modalities. The maximum increase in median normalized amplitude is 1.281 for the green channel, 0.594 for near-infrared and 1.111 for LASCA. Median Spearman’s rank correlation coefficient of the amplitude for green channel and LASCA is r= 0.89 and r= 0.71 for near-infrared and LASCA.

In acromegalic patients the serum levels of interleukin-33 and Resolvin D1 influence skin perfusion of hands: A pilot study

Acromegaly is a rare chronic disease, caused by the over-secretion of growth hormone (GH), that creates a pro-inflammatory state, but the exact mechanisms by which GH or insulin-like growth factor 1 (IGF-I) act on inflammatory cells are not fully understood. Aim of the study was to evaluate Interleukin-33 (IL33) and D-series resolvins 1 (RvD1) and the skin perfusion of hands in patients with acromegaly (AP) and healthy controls (HC).IL33 and RvD1 have been assessed in 20 AP and 20 HC. Nailfold videocapillaroscopy (NVC) was performed and skin perfusion of hands was assessed by laser speckle contrast analysis (LASCA) in both populations.IL33 was significantly higher in AP compared to HC [73.08 pg/ml (IQR 47.11-100.80 pg/ml) vs 41.5 4 pg/ml (IQR 20.16-55.49 pg/ml), p < 0.05] and RvD1 was significantly lower in AP than HC [36.1 pg/ml (IQR 27.88-66.21 pg/ml) vs 60.01 pg/ml (IQR 46.88-74.69 pg/ml), p < 0.05]. At LASCA, peripheral blood perfusion (PBP) was significantly lower in AP compared to HC [56.66 pU (IQR 46.29-65.44 pU) vs 87 pU (IQR 80-98 pU), p < 0.001]. The median values of ROI1 and ROI3 were significantly lower in AP compared to HC [112.81 pU (IQR 83.36-121.69 pU) vs 131 pU (IQR 108-135 pU), p < 0.05] and [59.78 pU (IQR 46.84-79.75 pU) vs 85 pU (IQR 78-98 pU), p < 0.05], respectively. The proximal-distal gradient (PDG) was observed in 8 of 20 (40 %) AP.Serum IL33 is higher in AP compared to HC; conversely, RvD1 is lower in AP compared to HC. Reduction of PBP of hands was present in AP compared to HC, probably due to endothelial dysfunction.

Microvascular endothelial dysfunction in skin is associated with higher risk of heart failure with preserved ejection fraction in women with type 2 diabetes: the Hoorn Diabetes Care System Cohort

BackgroundMicrovascular dysfunction plays a crucial role in complications of type 2 diabetes and might contribute to heart failure with preserved ejection fraction (HFpEF), a disease that disproportionally affects women. We aimed to investigate if presence and degree of microvascular dysfunction (MVD) in skin relates to markers of left ventricular diastolic dysfunction (LVDD) and HFpEF risk in adults with type 2 diabetes, and whether sex modifies this association.MethodsWe recruited 154 participants (50% women) from the Hoorn Diabetes Care System Cohort, a prospective cohort study, for in vivo evaluation of skin MVD, echocardiography and blood sampling. MVD was assessed by laser speckle contrast analysis combined with iontophoresis of insulin, acetylcholine and sodium nitroprusside (SNP). We performed a cross-sectional analysis of the association between perfusion responses and echocardiographic and clinical markers of LVDD and the H2FPEF score by multivariable linear regression analysis adjusted for confounders. Sex was evaluated as a potential effect modifier and the analysis was stratified.ResultsMean age was 67 ± 6y, mean HbA1c 7.6 ± 1.3%. Women were more frequently obese (54.5 vs. 35.1%), had higher NT-proBNP plasma levels (80, IQR:34–165 vs. 46, 27–117 pg/ml) and E/E’(13.3 ± 4.3 vs. 11.4 ± 3.0) than men. Eleven women and three men were diagnosed with HFpEF, and showed lower perfusion response to insulin than those without HFpEF. A lower perfusion response to insulin and acetylcholine was associated with higher HFpEF risk in women, but not men (10% decreased perfusion response was associated with 5.8% [95%CI: 2.3;9.4%] and 5.9% [1.7;10.1%] increase of the H2FPEF score, respectively). A lower perfusion response to SNP was associated with higher pulmonary arterial systolic pressure in men while a lower perfusion response to acetylcholine associated with higher LV mass index in women and with worse LV longitudinal strain in the total population. No significant associations were found between perfusion responses and conventional LVDD markers.ConclusionsImpaired microvascular responses to insulin and acetylcholine in skin confers a higher risk of HFpEF in women with type 2 diabetes. In vivo measures of systemic MVD could represent novel risk markers for HFpEF, opening new avenues for the prevention of HFpEF in type 2 diabetes.

Comparison of different forms of Raynaud's phenomenon by LASCA proximal-distal gradient perfusion.

To evaluate finger proximal-distal gradient (PDG) perfusion in subjects with primary Raynaud's phenomenon (PRP), then making comparisons with systemic sclerosis (SSc) patients and healthy controls (HC). Consecutive adult PRP subjects were enrolled, along with an equal number of SSc and HC. Peripheral blood perfusion of the hands was assessed by laser speckle contrast analysis (LASCA). PDG was then calculated applying a generalizable formula independent of both intra- and inter-personal factors. Non-specific anti-nuclear autoantibody (ANA) isolated positivity was assessed. Fifty PRP patients (88 % female, mean age 45 ± 17.9 years) were enrolled, along with 50 SSc patients and 50 HC. After adjusting mean PDG results for age and sex, no significant differences emerged between PRP and SSc (1.80 ± 0.43 vs 1.76 ± 0.53; p = 0.294). Conversely, PRP values were significantly reduced when compared to HC (2.72 ± 0.37; p < 0.001). Among PRP subjects, no significant differences were found regarding isolated ANA positivity (1.86 ± 0.44 vs 1.74 ± 0.44; p = 0.42). PRP and SSc seems to share the same basal PDG perfusion impairment assessed by LASCA. Isolated ANA positivity, in the absence of clinical and capillaroscopic suspicion for secondary causes, should not be considered an exclusion criterion for PRP classification.

Serum kynurenic acid is lower in systemic sclerosis patients with microvascular damage of hands.

Endothelial dysfunction occurs early in systemic sclerosis (SSc), leading to tissue hypoxia, vasoconstriction and fibrosis. It has been demonstrated that endothelial cells (ECs) are able to produce kynurenic acid (KYNA) in response to vascular inflammation, due to its anti-inflammatory and anti-oxidants activity. In SSc patients, blood perfusion of hands, assessed by laser speckle contrast analysis (LASCA), correlated negatively with the extent of the nailfold microvascular damage, scored according to nailfold videocapillaroscopy (NVC) classification. Aim of this study was to evaluate the difference of serum KYNA in SSc patients with different stages of microvascular damage. Serum KYNA was assessed in 40 SSc patients at the enrolment. NVC was performed to evaluate capillaroscopic patterns (early, active and late). LASCA was performed to evaluate mean peripheral blood perfusion (PBP) of both hands and to evaluate the proximal-distal gradient (PDG). Median PDG was significantly lower in SSc patients with late NVC pattern compared to SSc patients with early and active NVC pattern [3.79pU (IQR -8.55-18.16) vs 23.55pU (IQR 14.92-43.80), p<0.01]. Serum KYNA was significantly lower in SSc patients with late NVC pattern compared to SSc patient with early and active NVC pattern [45.19ng/mL (IQR 42.70-54.74) vs 52.65ng/mL (IQR 49.99-60.29), p<0.05]. Moreover, SSc patients without PDG had significantly lower serum KYNA than in SSc patients with PDG [48.03ng/mL (IQR 43.87-53.68) vs 59.27ng/mL (IQR 49.15-71.00), p<0.05]. KYNA is lower in SSc patients with late NCV pattern and without PDG. KYNA may be associated with early endothelial dysfunction.

Bedding as a variable affecting fasting blood glucose and vascular physiology in mice.

Rodent husbandry requires careful consideration of environmental factors that may impact colony performance and subsequent physiological studies. Of note, recent reports have suggested corncob bedding may affect a broad range of organ systems. As corncob bedding may contain digestible hemicelluloses, trace sugars, and fiber, we hypothesized that corncob bedding impacts overnight fasting blood glucose and murine vascular function. Here, we compared mice housed on corncob bedding, which were then fasted overnight on either corncob or ALPHA-dri bedding, a virgin paper pulp cellulose alternative. Male and female mice were used from two noninduced, endothelial-specific conditional knockout strains [Cadherin 5-cre/ERT2, floxed hemoglobin-α1 (Hba1fl/fl) or Cadherin 5-cre/ERT2, floxed cytochrome-B5 reductase 3 (CyB5R3fl/fl)] on a C57BL/6J genetic background. After fasting overnight, initial fasting blood glucose was measured, and mice were anesthetized with isoflurane for measurement of blood perfusion via laser speckle contrast analysis using a PeriMed PeriCam PSI NR system. After a 15-min equilibration, the mice were injected intraperitoneally with the α1-adrenergic receptor agonist, phenylephrine (5 mg/kg), or saline, and monitored for changes in blood perfusion. After a 15-min response period, blood glucose was remeasured postprocedure. In both strains, mice fasted on corncob bedding had higher blood glucose than the pulp cellulose group. In the CyB5R3fl/fl strain, mice housed on corncob bedding displayed a significant reduction in phenylephrine-mediated change in perfusion. In the Hba1fl/fl strain, phenylephrine-induced change in perfusion was not different in the corncob group. This work suggests that corncob bedding, in part due to its ingestion by mice, could impact vascular measurements and fasting blood glucose. To promote scientific rigor and improve reproducibility, bedding type should be routinely included in published methods.NEW & NOTEWORTHY This study demonstrates real-time measurement of changes in perfusion to pharmacological treatment using laser speckle contrast analysis. Furthermore, this investigation revealed that fasting mice overnight on corncob bedding has differential effects on vascular function and that there was increased fasting blood glucose in mice fasted on corncob bedding compared with paper pulp cellulose bedding. This highlights the impact that bedding type can have on outcomes in vascular and metabolic research and reinforces the need for thorough and robust reporting of animal husbandry practices.

FACTORS RELATED TO SKIN MICROVASCULAR DYSFUNCTION IN INDIVIDUALS WITH DIFFERENT RANGE OF GLUCOSE LEVELS

Objective: Existing data confirm the presence of microvascular dysfunction in hypertension and diabetes mellitus (DM). Prediabetes is recognized as a significant metabolic status, being a key factor in the occurrence of DM and there is increasing evidence concerning microvascular complications in prediabetes. Laser speckle contrast analysis (LASCA) is a non-invasive technique that can be used to evaluate skin microvascular function. The aim of our study was to assess cardiovascular factors that are possibly associated with microvascular reactivity in a population from normoglycaemia to DM. Design and method: Individuals with normoglycemia, prediabetes and diabetes without established cardiovascular disease were included in the study. In all participants, forearm skin blood flow was recorded under standardized conditions using a laser speckle contrast imager (PeriCam PSI NR System, Perimed). Post-occlusive reactive hyperaemia (PORH) was assessed following a standardized protocol and data were analyzed with a signal processing software (PIMSoft, Perimed). Skin microvascular reactivity was expressed as a percentage increase between baseline and peak perfusion (%). Office BP was measured in each participant according to a standard methodology and aortic blood pressure was assessed using the Sphygmocor device. Results: Fifty individuals (18 patients with prediabetes, 16 patients with DM and 16 controls) were included in the study. In the univariate model both glucose levels and aortic systolic blood pressure (aSBP) correlated inversely with microvascular reactivity (r = -0.382 and r = -0.349, p&lt;0.01 for both comparisons) However, in the multivariate model only the association with aSBP remained statistically significant (beta = -0.363, p&lt;0.05). Conclusions: Only central SBP, but not glucose predicted skin microvascular dysfunction in individuals with normoglycemia, prediabetes and diabetes and without established cardiovascular disease.

The assessment of moderate acne vulgaris face skin using blood perfusion and hyperspectral imaging-A pilot study.

Microcirculation is the flow of blood through the smallest vessels in the circulatory system. Capillaries respond to various pathologies much earlier than arteries and veins, the changes which indicate that the disease is already developing. Careful monitoring of the functioning of the capillary system often allows the detection of in vivo disorders at an early stage. The aim of the study was to evaluate the microcirculation within acne lesions. A noninvasive method of semi-quantitative blood perfusion measurement based on laser speckle contrast analysis (LASCA) and a quantitative assessment of the acne severity using the hyperspectral imaging method supported by image analysis and processing methods were used. The acne lesion perfusion was compared to the healthy skin perfusion of the control group. The reflectance in the range from 400 to 1000 nm was also compared for acne lesions and healthy skin. A dedicated version of the algorithm based on the gray-level co-occurrence matrix was used to compare differences between acne lesions and healthy skin. Blood perfusion in acne lesions is on average 117% higher than in healthy skin. The reflectance of acne lesions was lower in the range of 400-600 nm compared to the healthy skin. A statistically significant decrease in the reflectance of acne lesions was demonstrated for wavelengths: 434, 549, and 588 nm. Increased blood perfusion in acne lesions compared to healthy skin suggests increased chemotaxis of inflammatory cells and wound healing. Decrease points in skin reflectance resemble the absorption peaks for hemoglobin and coproporphyrin III produced by Cutibacterium acnes. Thus, the proposed methods may serve not only for the early detection of acne lesions, before they manifest themselves clinically for the naked eye, but may also be a tool for quantifying the effectiveness of acne treatment.

A lightweight real-time smartphone-based laser speckle contrast analyzer

Recently, laser speckle contrast analysis (LASCA) technology has spurred the exploration to instantly visualize microcirculatory tissue blood perfusion in clinical diagnosis, due to its non-contact, non-invasive and rapid imaging advantages. However, traditional medical imaging systems used to perform laser speckle contrast imaging (LSCI) are expensive and their transportation needs prudence, limiting the wide availability of LASCA for personal preliminary diagnosis. In this article, a low-cost, lightweight and portable smartphone-based laser speckle contrast imaging (smartphone-LSCI) is proposed to address this issue. With a built-in image sensor and powerful computational capability of the smartphone, the proposed system could be utilized to estimate the speckle contrast of human skin under various conditions and obtain information of the blood flow velocity of capillaries along with the degree of blood perfusion. Through experiments and theoretical analysis, we systematically studied the feasibility and robustness of image sensors on smartphones-LSCI. Experiments prove that ambient light has little influence on the performance of our smartphone-LSCI. In addition, the speckle image processing flow of smartphone-LSCI is proposed, together with an enhanced spatial LASCA (esLASCA) method. In the experiments with a low-cost smartphone, i.e., Redmi K40, the 4000×3000 pixels images can be processed at a frame rate of 20Hz. The consumption time of both the existing state-of-the-art roll algorithm and the proposed esLASCA is linearly proportional to the width (height) of the image resolution. However, our proposed method shows a slower growth rate and lower computational time when the window size is small.

Corncob bedding alters fasting blood glucose and vascular function in mice

Rodent husbandry requires careful consideration of environmental factors that may impact colony performance and subsequent physiological studies. Of note, recent reports have suggested corncob bedding is potentially a confounding variable affecting a broad range of organ systems. As corncob bedding may contain digestible hemicelluloses, trace sugars, and fiber, we hypothesized that corncob bedding impacts murine vascular function and overnight fasting blood glucose. Here, we compared mice housed on corncob bedding, which were then fasted overnight on either corncob or ALPHA-dri bedding, a paper cellulose alternative. Male and female mice were used from two non-induced, endothelial-specific conditional knock-out strains (Cadherin 5-CreERT2, floxed hemoglobin alpha 1 [Hba1] or Cadherin 5-CreERT2, floxed cytochrome B5 reductase 3 [CyB5R3]) on a C57BL/6J genetic background. After fasting overnight, initial blood glucose was measured, and mice were anesthetized with isoflurane for measurement of blood perfusion via laser speckle contrast analysis using a PeriMed PeriCam PSI NR system. After a 15-minute equilibration, the mice were injected intraperitoneally with phenylephrine (5 mg/kg) or saline and monitored for changes in blood perfusion. After a 15-minute response period, blood glucose was remeasured post-procedure. Consistently, mice fasted on corncob bedding had higher blood glucose than the ALPHA-dri group. In the CyB5R3 strain, corncob bedding caused a reduction in phenylephrine-mediated vasoconstriction. In the Hba1 strain, phenylephrine-induced vasoconstriction was more variable in the corncob group. Altogether, this work suggests that corncob bedding could be a confounding variable for vascular measurements and fasting blood glucose in mice. To promote scientific rigor and improve reproducibility, bedding type should be included in published methods. NIH R01HL155618 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Description of Peripheral Blood Perfusion by Laser Speckle Contrast Analysis (LASCA) in 'Early' versus 'Clinically Overt' Systemic Sclerosis in Routine Clinics.

To investigate in an unselected, systemic sclerosis (SSc) cohort if baseline laser speckle contrast analysis (LASCA) peripheral blood perfusion (PBP) measurements differ between 'early' SSc (without skin involvement, or 'limited' SSc-LSSc) and 'clinically overt' SSc (with skin involvement, limited cutaneous SSc-LcSSc and diffuse cutaneous SSc-DcSSc) in routine setting. A group of twenty consecutive 'early' SSc patients and forty consecutive 'clinically overt' SSc patients (twenty LcSSc and twenty DcSSc) underwent clinical and LASCA examinations (to assess the peripheral blood perfusion [PBP] of both hands volar). No statistically significant difference in adjusted PBP was found in the 'early' versus the 'clinically overt' group (p = 0.77) when adjusted for possible confounding factors (e.g., vasoactive medication, active smoking, history of DTL and disease duration). A wide variability was noted when observing the individual datapoints of each subset. This study with an unselected SSc population in daily routine, non-research setting, showed there was no difference in adjusted PBP at baseline between 'early' SSc and 'clinically overt' SSc when corrected for possible confounding factors. Interestingly a wide variation of individual datapoints were observed in each subset, which emphasizes the heterogeneity of SSc.

Clinical and LASCA preliminary data on selexipag efficacy for the treatment of digital vasculopathy in systemic sclerosis.

Systemic sclerosis (SSc) is burdened by Raynaud's phenomenon (RP) and digital ulcers (DUs) and sometimes standard vasoactive therapies are ineffective or contraindicated. Selexipag is an oral selective IP prostacyclin receptor agonist approved for the treatment of SSc-related pulmonary arterial hypertension. We aimed to evaluate clinical and instrumental efficacy of selexipag in SSc digital vasculopathy. SSc patients with severe digital vasculopathy refractory or with contraindication to all other vasoactive therapies were administered selexipag, evaluating at baseline and after 3 months clinical outcomes regarding RP and DUs and digital perfusion assessed by laser speckle contrast analysis (LASCA). Selexipag was administered to 9 SSc patients (66.6% female, mean age 52.3 ±16.6 years). One of them had to stop the drug for adverse effects. After three months selexipag determined a significant reduction of RP daily episodes (p=0.012) and RP mean duration (p=0.044). DUs decreased from 10 to 4 without reaching the statistical significance. A significant improvement in the mean perfusion of the fingers (p=0.016) was observed at LASCA. Selexipag showed good potential for the treatment of SSc-digital vasculopathy. Our results are certainly preliminary but yet quite encouraging. New trials for the evaluation of selexipag efficacy in SSc-digital vasculopathy are needed.