What have we learned on pre, very early, and early systemic sclerosis microcirculatory pathophysiology? A scoping review.

OBJECTIVE: Microvascular dysfunction is an early event in the pathogenesis of systemic sclerosis (SSc). The objective of this scoping review is to update the current information and the level of knowledge about the mechanisms of microvascular dysfunction in pre-SSc, very early diagnosis of SSc (VEDOSS) and early SSc. METHODS: A PubMed® database search allowed us to include original data from full-length articles in English in which the main topic was microvascular dysfunction in pre-SSC, VEDOSS or early SSc. Data was extracted using a customized form. RESULTS: In the present review 437 articles were identified, and 42 studies included, reporting data from a total of 1069 patients with pre-SSc, VEDOSS or early-SSc. Distinct mechanisms of microvascular injury were identified comprising, angiogenesis and vasculogenesis, cell surface proteins and adhesion, molecules expression, cytokines profile, inflammatory and oxidation pathways, and skin perfusion determinants. Most of the studies were conducted in early SSc, with a reduced number in pre-disease stages, in which the prompt recognition of specific mechanisms and biomarkers may allow targeted treatment to prevent disease progression. CONCLUSIONS: Although different molecular expression patterns and signaling pathways related to microvascular dysfunction in pre-SSc, VEDOSS, and early SSc were identified, additional prospective longitudinal studies and combined work with functional evaluation of peripheral skin perfusion are needed.

Charting the course of Physiology within the post-Bologna European higher education area: Insights from Portugal.

The future of physiology has been a recurrent concern for physiologists and Physiological Societies within post-Bologna Europe and the European Higher Education Area (EHEA). Our paper provides an overview of Physiology teaching and research in Portugal, an EU member state and part of the EHEA. A descriptive study was designed to analyze data publicly available from the National Higher Education Directorate agency (DGES) from September to November 2022 to find all Portuguese syllabi containing at least one discipline related to human Physiology. A detailed database was established, including teaching staff, with a total of 365 courses/degrees and 764 Physiology disciplines. A bibliometric analysis of the identifiable lecturers' scientific production between 2017 and 2022 was made using Web of Science and PUBMED databases. Physiology is part of all health-related professions. However, universities and technical colleges differ greatly in programs, staff backgrounds, and scientific profiles. Medical schools were found to provide the most complete formation. Noteworthy, the profession of Physiologist has practically no expression within the EHEA, compared with the USA-UK realities. A better knowledge and understanding of these Physiology modalities in teaching and research within the EHEA will be instrumental to defining a stronger identity for European Physiology in the near future.

Lower-Limb Perfusion and Cardiovascular Physiology Are Significantly Improved in Non-Healthy Aged Adults by Regular Home-Based Physical Activities-An Exploratory Study.

Common daily activities including walking might be used to improve cardiovascular health in the presence of disease. Thus, we designed a specific home-based physical activity program to assess cardiovascular indicators in an older, non-active, non-healthy population. Ten participants, with a mean age of 62.4 ± 5.6 years old, were chosen and evaluated twice-upon inclusion (D0), and on day 30 (D30)-following program application. Perfusion was measured in both feet by laser Doppler flowmetry (LDF) and by polarised spectroscopy (PSp). Measurements were taken at baseline (Phase 1) immediately after performing the selected activities (Phase 2) and during recovery (Phase 3). Comparison outcomes between D0 and D30 revealed relevant differences in Phase 1 recordings, namely a significant increase in LDF perfusion (p = 0.005) and a significant decrease in systolic blood pressure (p = 0.008) and mean arterial pressure (MAP) (p = 0.037). A correlation between the increase in perfusion and the weekly activity time was found (p = 0.043). No differences were found in Phase 2, but, in Phase 3, LDF values were still significantly higher in D30 compared with D0. These simple activities, regularly executed with minimal supervision, significantly improved the lower-limb perfusion while reducing participants' systolic pressure and MAP, taken as an important improvement in their cardiovascular status.

Studying Erythromelalgia Using Doppler Flowmetry Perfusion Signals and Wavelet Analysis-An Exploratory Study.

Erythromelalgia (EM) is a rare disease, which is still poorly characterized. In the present paper, we compared the hand perfusion of one female EM patient, under challenges, with a healthy control group. Using a laser Doppler flowmeter (LDF) with an integrated thermal probe, measurements were taken in both hands at rest (Phase I) and after two separate challenges-post-occlusive hyperemia (PORH) in one arm (A) and reduction of skin temperature (cooling) with ice in one hand (B) (Phase II). The final measurement periods corresponded to recovery (Phases III and IV). The control group involved ten healthy women (27.3 ± 7.9 years old). A second set of measurements was taken in the EM patient one month after beginning a new therapeutic approach with beta-blockers (6.25 mg carvedilol twice daily). Z-scores of the patient's LDF and temperature fluctuations compared to the control group were assessed using the Wavelet transform (WT) analysis. Here, fluctuations with |Z| > 1.96 were considered significantly different from healthy values, whereas positive or negative Z values indicated higher or lower deviations from the control mean values. Cooling elicited more measurable changes in LDF and temperature fluctuations, especially in higher frequency components (cardiac, respiratory, and myogenic), whereas PORH notably evoked changes in lower frequency components (myogenic, autonomic, and endothelial). No significant Z-score deviations were observed in the second measurement, which might signify a stabilization of the patient's distal perfusion following the new therapeutic approach. This analysis involving one EM patient, while clearly exploratory, has shown significant deviations in WT-derived physiological components' values in comparison with the healthy group, confirming the interest in using cold temperature as a challenger. The apparent agreement achieved with the clinical evaluation opens the possibility of expanding this approach to other patients and pathologies in vascular medicine.

Nurse-led intervention for the management of bariatric surgery patients: A systematic review.

The prevalence of obesity has become a global health concern, and severe obesity is associated with various chronic diseases and decreased quality of life. Bariatric surgery has shown success in treating obesity. Nevertheless, some patients experience weight regain and unsatisfactory outcomes. Multidisciplinary interventions have been shown to improve postoperative outcomes. Case managers, often specialized nurses, play a crucial role in patient support and coordination of care. However, the diverse design of case-managing interventions hinders the assessment of their success. Thus, the aim of this review is to identify the most successful structural characteristics of case-managing interventions, with or without the support of e-Health, in the process of perioperative management of bariatric surgery patients. A systematic literature review was conducted following the PRISMA guidelines. PubMed, MEDLINE, EBSCOhost, and CINAHL databases were searched for relevant studies published in the last 10 years. Eligible studies included randomized controlled trials, controlled clinical studies, case studies, or observational studies that evaluated perioperative care in bariatric surgery. The PICO framework was used to frame the search strategy. The initial search yielded 225 articles, of which 10 studies met the inclusion criteria. Nurse-led case-managing interventions with a multidisciplinary approach showed positive results in weight loss, physical activity, and quality of life. Patient-centered care models were found to promote adherence to treatment and patient satisfaction. E-Health technologies improved quality of life but not weight loss. The duration of behavioral interventions and the long-term outcomes after surgery remained unclear. Nurse-led case-management interventions, with a focus on behavioral change and multidisciplinary approaches, show promise in improving outcomes in bariatric surgery patients. Patient-centered care models and longer term interventions may contribute to sustained weight loss and better postoperative outcomes. Further research is needed to determine the optimal duration of interventions and the long-term effects on weight maintenance.

Contemporary views on the future of physiology-a report from the 2019 P-MIG focus group.

Physiologists are seen as professionals with a unique understanding of life, health, and disease, essential to the progression of knowledge regarding human functions and health. Among these experts however, the thematic of the "Future of Physiology" has been regularly present in the agenda of physiology organizations around the world as various uncertainties about teaching and research in human physiology emerged. The Physiology Majors Interest Group (P-MIG) 2019 meeting provided the occasion for some strategic reasoning and planning, aiming to identify the trends that might drive future changes in human physiology. Twelve physiologists, all experts in different areas of Physiology research and teaching, nearly all based in North America, volunteered to participate in this focus group. The session was audio recorded. A verbatim transcript of the recording was then analyzed through thematic analysis, aiming to identify the most relevant themes for the future of Physiology and how these themes might unfold. The group concluded that a shared consciousness on general goals is present, meaning to preserve and develop the interdisciplinary/integrative nature, to promote more innovative teaching/learning practices, and to acknowledge technology as the main catalyst for research and teaching innovation and progress. This consciousness was present in all participants. The group also concluded that transformation will likely need to be more effective, and should involve the Physiological Societies and organizations around the world. Special emphasis was placed on the need to share common competences for curriculum definition, common guidance for teaching practice, and common assessment procedures, with particular attention recommended toward science communication.

Mediterranean Diet Adherence and Its Relationship to Metabolic Markers and Body Composition in Portuguese University Students.

BACKGROUND: Transitioning to university involves several changes, which might affect dietary habits. The present study aimed to assess the potential relationships involving adherence to the MedDiet, body composition, and metabolic markers within a Portuguese university sample. METHODS: A cross-sectional study involved 70 participants, 52 women, and 18 men (23.00 ± 7.00 years old and a BMI of 21.99 ± 2.79 kg/m2). The average MedDiet adherence of participants was 9.23 points, as evaluated by the 14 point validated questionnaire, with classifications of low and high (under or over 9 points, respectively). Body composition was assessed using X-ray dual densitometry (DXA), and metabolic markers were collected from capillary blood. RESULTS: Statistically significant differences in HDL cholesterol and the total/HDL cholesterol ratio were found between groups. Lower levels (p < 0.05) of visceral (VAT) and subcutaneous adipose tissue (SAT), BMI, and waist circumference were found in the higher MedDiet adherence group. Those measures were negatively correlated (p < 0.05) with the adherence scores to the MedDiet. CONCLUSION: Higher adherence to MedDiet seemed to have a favorable and important impact on lipid profiles, primarily HDL-c. A positive relationship between MedDiet adherence and body composition distribution was also described, mostly due to the influence of higher adherence to MedDiet at lower levels of VAT and SAT in Portuguese university students.

Bioimpedance and Dual-Energy X-ray Absorptiometry Are Not Equivalent Technologies: Comparing Fat Mass and Fat-Free Mass.

Bioimpedance (BIA) is the most frequently used technology for body composition assessment at a daily clinical level, mostly due to its low price and user-friendly operation. However, many doubts persist regarding its physiological meaning and applicability. The present study aimed to compare one BIA system and the Dual-Energy X-ray Absorptiometry (DXA) for the characterization of body composition in a previously selected cohort of healthy adult participants. A descriptive observational cross-sectional study included a final sample of 121 participants, 93 women and 28 men, with a mean age of 28.26 ± 9.72 years old and a mean body mass index (BMI) of 22.68 ± 3.13 kg/m2. Statistics involved paired t-tests and agreement analysis by the Bland-Altman method. BIA underestimated the percent body fat (%BF) by 5.56% and overestimated Fat-Free Mass (FFM) by 2.90 kg. A strong positive correlation between both technologies was found for FFM (r = 0.980) and the %BF (r = 0.932), but the disagreement was statistically significant (p < 0.001). Although DXA and BIA seem to correlate, these technologies are not congruent. Therefore, the risk of (mis)interpretation and bias is clear with BIA, potentially impacting the nutritional planning of clinical dietitians and the further results of its patients.

The Impact of Kefir on Epidermal Water Homeostasis in Healthy Human Skin.

Kefir, a symbiotic consortium of diverse bacteria and yeasts, is one of the most popular probiotic foods on the market. Its consumption has been referred to as beneficial in human skin health, namely in the reinforcement of skin's barrier function. This benefit likely results from the productive activity of lactic acid bacteria during kefir fermentation. Lactic acid is naturally present in the skin, and actively contributes to epidermal water dynamics and "barrier." Few studies have been conducted regarding the impact of probiotic consumption in human epidermal water homeostasis. Therefore, this study was designed to explore the impact of the regular consumption of kefir on the skin water dynamics in a group of participants with healthy skin. Participants (n = 27) were healthy female volunteers from whom twelve consumed 100 mL of kefir every day for eight weeks as part of their diet. The remaining (untreated) participants served as the control group. Epidermal water balance was assessed by measuring transepidermal water loss (TEWL) and stratum corneum (SC) hydration on three different occasions-at baseline (T0), after four weeks (T4) and after eight weeks (T8) of interventive kefir consumption. Our study revealed a significant reduction in TEWL (p = 0.043) in the kefir group after eight weeks of regular consumption. In the same period, no differences were found for TEWL in the control group (p = 0.997). Regarding hydration, skin dryness was progressive in the control group, with a significant reduction in SC hydration (p = 0.002) at T8 in comparison to T0. In the kefir group, SC hydration was preserved between T0 and T8 (p = 0.997), which we believe to be related to epidermal "barrier" reinforcement. Our study seems to confirm that the regular consumption of kefir does improve cutaneous water balance even in healthy skin.

The Long-Term Association between Physical Activity and Weight Regain, Metabolic Risk Factors, Quality of Life and Sleep after Bariatric Surgery.

Bariatric surgery is currently regarded as a safe and effective long-term procedure for the treatment of obesity and related comorbidities. We analyzed the association between physical activity (PA), weight regain, metabolic risk factors and quality of life in patients submitted to bariatric surgery. This study also aimed to preliminarily assess how physical activity and weight regain may be associated with sleep quality and sedentary behavior. This was an observational study, with retrospective data collection and a cross-sectional survey. Retrospective clinical data were collected from a sample of 84 individuals who had undergone bariatric gastric bypass surgery at least five years prior to the study period in an Integrated Responsibility Center for Obesity and Metabolic Diseases Surgery. The survey, developed from validated questionnaires and applied in telephone interviews, focused on health data, associated comorbidities, quality of life, physical activity, sedentary behavior and sleep. Descriptive and comparative statistics were performed with a 95% confidence level. Bariatric surgery induced a significant weight loss in the first year after surgery. Our analysis also revealed that lower levels of PA were associated with weight regain. Quality of life as well as sleep quality were inversely related to weight regain, as well as sedentary behavior in general. Primary and secondary outcomes of bariatric surgery can be better achieved if the practice of PA could be maintained for consecutive years.

Multispectral Optoacoustic Tomography for Functional Imaging in Vascular Research.

Microcirculatory impairment has been recognized in various disease processes, underlying this growing theme within vascular research. In recent years, the development of live imaging systems has set the (analytical) pace in both basic and clinical research, with the objective of creating new instruments capable of providing real-time, quantifiable endpoints with clinical interest and application. Near-infrared spectroscopy (NIRS), positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging (MRI) are available, among other techniques, but cost, image resolution, and reduced contrast are recognized as common challenges. Optoacoustic tomography (OT) offers a new perspective on vascular functional imaging, combining state-of-the-art optical absorption and spatial resolution capacities (from micrometer optical to millimeter acoustic resolution) with tissue depth. In this study, we tested the applicability of multispectral optoacoustic tomography (MSOT) for functional imaging. The system uses a tunable optical parametric oscillator (OPO) pumped by an Nd: YAG laser, providing excitation pulses sensed by a 3D probe at wavelengths from 680 nm to 980 nm. Images obtained from the human forearm were reconstructed through a specific algorithm (supplied within the manufacturer's software) based on the response of specific chromophores. Maximal Oxygenated Hemoglobin (Max HbO2) and Deoxygenated Hemoglobin (Max Hb), Total Hemoglobin (HbT), and mean Oxygen Saturation (mSO2) to vascular density (µVu), inter-unit average distances (ζAd), and capillary blood volume (mm3) may be measured using this system. The applicability potential found with this OT system is relevant. Ongoing software developments will surely improve the utility of this imaging system.

Comparison between Different Groups of Vegetarianism and Its Associations with Body Composition: A Literature Review from 2015 to 2021.

BACKGROUND: Vegetarian and vegan diets have become increasingly popular in the last years for many reasons, including their association with various health benefits when compared to omnivorous diets. The main objective of the study was to collect recent (2015-2021) scientific evidence for potential implications between a vegetarian/vegan diet and an individuals' body composition. METHODS: A literature search was conducted in PubMed, with 22 studies selected for inclusion in our collective evaluation. Of the 22 studies included, there were 12 randomized controlled trials, 1 nonrandomized controlled trial, 1 comparative study, and 8 cross-sectional. The overall sample included in this study consists of 436,178 participants, 10,090 of whom were vegetarians, 5044 vegans, and 421,044 omnivores. RESULTS: Most studies, 17 out of 22, reported a significant positive relationship between a plant-based diet and body composition. CONCLUSION: There is scientifically sound evidence that vegan or vegetarian diets are associated with weight and body mass index reduction and, in some cases, fat mass distribution changes.

Lower Limb Dynamic Activity Significantly Reduces Foot Skin Perfusion: Exploring Data with Different Optical Sensors in Age-Grouped Healthy Adults.

INTRODUCTION: The human lower limb is widely used as a model to study in vivo microcirculatory physiology and pathophysiology. It is a preferential target for critical comorbidities (overweight, diabetes, and peripheral vascular disease). Movement and activity are consistently regarded as beneficial, but the related adaptive physiology is still poorly understood. Our goal was to better identify the foot microcirculatory changes after a regular walking gait activity in healthy subjects of different ages. METHODS: Twelve healthy participants of both sexes, with normal BMI and Ankle-Brachial Index, were selected and grouped according to age - group I (21.0 ± 1 y.o.) and group II (55.8 ± 3 y.o.). The protocol involved 2 phases of 5-min duration each - phase 1, a static standing position, and phase 2, 5-min walking with a comfortable pace on a pre-established circuit. Perfusion changes were assessed in the dorsal region of both feet before (baseline, phase 1) and after (phase 2) the gait period by noninvasive optical technologies - laser Doppler flowmetry (LDF), photoplethysmography, and polarized spectroscopy (PSp). Comparative statistics were performed with a 95% confidence level. RESULTS: All instruments detected an asymmetric nonsignificant perfusion between right and left feet during rest in all participants with values in females consistently lower than men. Older participants exhibited lower baseline values than the younger group. Gait evoked a perfusion reduction in all participants relative to phase 1 detected with all technologies, with statistically significant changes recorded with LDF (group I, p = 0.033, and group II, p = 0.028) and PSp (group II, p = 0.041). Furthermore, LDF revealed that gait significantly reduced perfusion velocity in the older group (p = 0.003). Corresponding changes in the younger group were present but discrete. Recovery to baseline levels was also slower in the older group. DISCUSSION/CONCLUSIONS: Our results confirm that perfusion is age dependent and demonstrate the clinical relevance of simple dynamic activities such as gait. This reduction of the dorsal foot perfusion occurs in depth, being more pronounced with the movement intensity, suggesting a wide application potential in early diagnostics as for rehabilitation.

Screening the dermatological potential of plectranthus species components: antioxidant and inhibitory capacities over elastase, collagenase and tyrosinase.

A series of Plectranthus spp. plant extracts (aqueous, acetonic, methanolic and ethyl acetic) obtained from eight different species, and previously isolated compounds (ranging from polyphenols, diterpenes and triterpenes), were assayed for in vitro inhibition of the skin-related enzymes tyrosinase, collagenase and elastase, and for studying their antioxidant properties. The ethyl acetic extracts of P. grandidentatus and P. ecklonii registered the highest antioxidant activity, whereas acetonic, methanolic and ethyl acetic extracts of P. ecklonii, P. grandidentatus, P. madagascariensis and P. saccatus concerning the enzymatic inhibition assays revealed high anti-tyrosinase and anti-collagenase activities. From the isolated compounds tested, abietane diterpenes and triterpenes were highly active against tyrosinase and elastase activity. Overall, the experimental results showed the powerful antioxidant and inhibitory action on skin-related enzymes tyrosinase, collagenase and elastase of Plectranthus spp. extracts and/or isolated compounds, supporting their further research as bioactive metabolites against skin sagging and hyperpigmentation in cosmetic and pharmaceutical formulations.

The revised EEMCO guidance for the in vivo measurement of water in the skin.

BACKGROUND: Noninvasive quantification of stratum corneum water content is widely used in skin research and topical product development. METHODS: The original EEMCO guidelines on measurements of skin hydration by electrical methods and transepidermal water loss (TEWL) by evaporimeter published in 1997 and 2001 have been revisited and updated with the incorporation of recently available technologies. RESULTS: Electrical methods and open-chamber evaporimeters for measurement of TEWL are still the preferred techniques to measure the water balance in the stratum corneum. The background technology and biophysics of these instruments remain relevant and valid. However, new methods that can image surface hydration and measure depth profiles of dermal water content now available. Open-chamber measurement of TEWL has been supplemented with semiopen and closed chamber probes, which are more robust to environmental influence and therefore convenient to use and more applicable to field studies. However, closed chamber methods interfere with the evaporation of water, and the methods cannot be used for continuous monitoring. Validation of methods with respect to intra- and inter-instrument variation remains challenging. No validation standard or test phantom is available. RESULTS AND CONCLUSIONS: The established methods for measurement of epidermal water content and TEWL have been supplemented with important new technologies including methods that allow imaging of epidermal water distribution and water depth profiles. A much more complete and sophisticated characterization of the various aspects of the dermal water barrier has been accomplished by means of today's noninvasive techniques; however, instrument standardization and validation remain a challenge.

Excessive Weight Favours Skin Physiology - Up to a Point: Another Expression of the Obesity Paradox.

BACKGROUND/AIMS: Recently classified as an epidemic by the WHO, obesity (as well as the state of being overweight) clearly affects significant populations across all ages. The relationship between obesity and some diseases (e.g. cardiovascular ones) is known, although many paradoxes remain to be explained. Very little information is available, however, regarding its impact on skin physiology and skin disease. This study aims to examine the influence of excessive weight on epidermal hydration and transepidermal water loss, key variables of skin water balance and skin biomechanics. METHODS: A convenience sample of 89 healthy female volunteers was selected and divided into 4 groups, according to their BMI (body mass index), as normal (control), overweight, obese (I and II), and morbid. Skin physiology was quantitatively assessed in all individuals in 4 anatomical areas using non-invasive biometrical analysis by reference instrumentation. Descriptive and comparative statistics were applied, adopting a confidence level of 95%. RESULTS: A non-linear alteration for all variables was detected as a function of BMI. CONCLUSION: Results suggest that excessive weight might favour skin performance within certain limits, reflecting a particular adaptation of the skin to the weight gain and body contour.

Cutaneous biocompatible rutin-loaded gelatin-based nanoparticles increase the SPF of the association of UVA and UVB filters.

The encapsulation of natural ingredients, such as rutin, can offer improvements in sun protection effectiveness. This strategy can provide enhanced flavonoid content and produces an improved bioactive compound with new physical and functional characteristics. As an alternative to common synthetic-based sunscreens, rutin-entrapped gelatin nanoparticles (GNPs) were designed and associated with ethylhexyl dimethyl PABA (EHDP), ethylhexyl methoxycinnamate (EHMC) and methoxydibenzoylmethane (BMDBM) in sunscreen formulations. The purpose of this study was to develop rutin-loaded gelatin nanoparticles and characterize their physicochemical, thermal, functional and safety properties. Rutin-loaded gelatin nanoparticles increased antioxidant activity by 74% relative to free-rutin (FR) solution. Also, this new ingredient upgraded the Sun Protection Factor (SPF) by 48%, indicating its potential as a raw material for bioactive sunscreens. The safety profile indicated that GNPs and glutaraldehyde (GTA) decreased HaCaT cell viability in a concentration/time-dependent manner. However, both blank nanoparticles (B-NC) and rutin-loaded nanoparticles (R-NC) had good performance on skin compatibility tests. These results functionally characterized rutin-loaded nanoparticles as a safe SPF enhancer in sunscreens, especially in association with UV filters.

Dietary water affects human skin hydration and biomechanics.

It is generally assumed that dietary water might be beneficial for the health, especially in dermatological (age preventing) terms. The present study was designed to quantify the impact of dietary water on major indicators of skin physiology. A total of 49 healthy females (mean 24.5±4.3 years) were selected and characterized in terms of their dietary daily habits, especially focused in water consumption, by a Food Frequency Questionnaire. This allowed two groups to be set - Group 1 consuming less than 3,200 mL/day (n=38), and Group 2 consuming more than 3,200 mL/day (n=11). Approximately 2 L of water were added to the daily diet of Group 2 individuals for 1 month to quantify the impact of this surplus in their skin physiology. Measurements involving epidermal superficial and deep hydration, transepidermal water loss, and several biomechanical descriptors were taken at day 0 (T0), 15 (T1), and 30 (T2) in several anatomical sites (face, upper limb, and leg). This stress test (2 L/day for 30 days) significantly modified superficial and deep skin hydration, especially in Group 1. The same impact was registered with the most relevant biomechanical descriptors. Thus, in this study, it is clear that higher water inputs in regular diet might positively impact normal skin physiology, in particular in those individuals with lower daily water consumptions.

Regarding the quantification of peripheral microcirculation--Comparing responses evoked in the in vivo human lower limb by postural changes, suprasystolic occlusion and oxygen breathing.

The human skin is an interesting model to explore microcirculation, particularly if using noninvasive technologies such as LDF (Laser Doppler Flowmetry) and tc (transcutaneous) gasimetry and methods as near as possible from the normal physiological state. In this study, we combined those technologies with three classical approaches--leg raising from supine, suprasystolic occlusion (in the ankle), and normobaric oxygen breathing to explore distal peripheral circulation in the foot. These methods are often cited, but a comparative assessment has not been done. The goal of this study was to identify relevant flow related descriptors, method-related advantages and pitfalls, and eventually, to find the best experimental approach. Volunteers (both genders, 22.1 ± 3.7 years old) were subjected to these methods and variables registered during basal, challenge and stabilization phases. Descriptive and comparative statistics were obtained, adopting a 95% confidence level. All flow-related quantitative descriptors potentially useful for the analysis were identified and compared. As expected, male patients consistently showed higher LDF levels and transepidermal water loss (TEWL) and lower tcpO2 values. However, lower results were recorded in the supine position, suggesting a postural dependence. Both leg raising and suprasystolic occlusion produced a hyperemic response after provocation, although different in magnitude, significantly reducing LDF and tcpO2 during provocation. The oxygen breathing method provided the most patient-friendly protocol, consistently reducing LDF (potentially by the inhibition of production of local vasodilators). TEWL increased during the provocation phase in all protocols, although not significantly. Baseline tcpO2 was found to correlate positively with the peak tcpO2 during oxygen breathing and basal LDF with peak flow during leg raising and suprasystolic occlusion. No statistical correlation between TEWL and LDF could be demonstrated under the current experimental conditions. We conclude that although equally useful considering the purpose, these methods involve very different practicalities and do not provide the same information. Also noteworthy, LDF is a highly sensitive indicator that could be further explored to look deeper into blood flow regulating mechanisms.

In vivo assessment of peripheral vascular function by tcpO2 and skin blood flow modelling.

There are multiple techniques and methods to assess peripheral vascular function in vivo but not without limitations. More discriminative, sensitive and also practical evaluation strategies are needed to fully characterize the peripheral vascular function. In the present work, a new quantitative descriptor, the 'elimination half-life time' was developed from flow-related variables as a non-invasive microcirculatory rate parameter to describe vascular dynamics. Fifty-four healthy volunteers and six type 2 diabetic patients, both genders, were submitted to a dynamical procedure consisting in the inhalation of a 100% saturated atmosphere of oxygen for 10 min. The tcpO(2) and microcirculatory blood flow [Laser Doppler Flowmetry (LDF)] were measured in a randomly selected leg with a Periflux 5000 system before, during and after the procedure. A monocompartmental model was adjusted to tcpO(2) and LDF data. The tcpO(2) constant elimination rate, expressed as the Oxygen elimination half-life, was used as an indicator of the vulnerability of peripheral tissue and compared in healthy versus non-healthy individuals. Under normal conditions, the saturated ventilation increases the tissue's O(2) availability, as an expression of the natural capacity to adjust the tissue hemodynamics to new metabolical/perfusion conditions. Diabetic patients are expected to suffer vascular impairment and ischemia. Under O(2) overloading conditions, those hypoxic territories tend to uptake all the delivered oxygen, expressed as a significant increase in the O(2) elimination half-life. This approach allows to propose 'elimination half-life time' as the first quantitative descriptive parameter combining miogenic, hemodynamic and metabolic aspects of the microcirculatory physiology and to help to identify the individual's vascular vulnerability.