Search

Photoplethysmography (PPG) is a noninvasive optical technology, with applications including vital sign extraction and patient monitoring. The PPG acquisition skin type may be of importance. Skin is either nonglabrous (~90%) or glabrous (~10%). Clinical PPG collection is typically from glabrous (fingerpad), while proliferating wearables collecting PPG, which may perform critical functions like arrythmia detection, often acquire from atypical sites. Glabrous skin has significant differences from nonglabrous, including microcirculation, yet comparisons between their PPG signals have not been well reported. Using a smartphone‐based remote/contactless PPG, a pilot dataset was collected from the hands (palmar/dorsal) of five healthy volunteers. The data shows statistically significant lead time (52 ± 36 ms) of glabrous over nonglabrous. Further, a trend of glabrous amplitude increase over nonglabrous (31%) was found. Although our study has a small number of participants, these results further the characterization of PPG skin differences, and can be used to inform development of PPG‐based devices. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine data demonstrating that Scarpa's fascia, a superficial fascia of the anterior abdominal wall, is a vascularized tissue. Specimens of the fascia of seven volunteers undergoing abdominoplasty surgical procedures at the Plastic Surgery Unit of the University of Padova Medical Center were collected. Fractal analysis and quantitative assessment of the vascular network of the fascia was carried out, exploiting the presence of blood in the vessels. Each sample was divided and processed for histological/immunohistochemical analysis (into 5 micron-paraffin embedded sections and cryo-sectioned free-floating samples) as well as for electron microscopy study. A rich vascular pattern forming a fine, dense meshwork with an area percentage of 6.20% ± 2.10% von Willebrand factor stained vessels was noted in all the specimens of the fascia examined; the area percentage of the αSMA-stained vessels was 2.93% ± 1.80%. The diameters of the vessels fell between the 13 and 65 μm range; the network was composed of arteries, veins, capillaries and lymphatic segments. Topological results showed that the vascular network within Scarpa's fascia is well branched (segments: 6615 ± 3070 and 8.40 ± 3.40 per mm 2 ; crossing points: 3092 ± 1490 and 3.40 ± 1.90 per mm 2 ). Fractal analysis (fractal dimension = 1.063 ± 0.10; lacunarity = 0.60 ± 0.10) revealed that this particular vascular network has an optimal spatial distribution and homogeneity occupying the entire space of the superficial fascia. These findings could undoubtedly be useful to plastic surgeons as well as to pain management specialists., (© 2022 American Association of Clinical Anatomists and British Association of Clinical Anatomists.)

This study investigated the responses of skin blood flow (SkBF) in glabrous and nonglabrous skin to graded submaximal dynamic exercise and its recovery.We enrolled eight healthy young men with comparable maximal oxygen uptake (VO2max). Laser-Doppler flux (LDF) was assessed on the finger pulp (glabrous site) and the volar forearm (nonglabrous site) simultaneously with skin temperature, heart rate and blood pressure; cutaneous vascular conductance (CVC) was calculated. Subjects were monitored before (baseline), during and 25 minutes after incremental cycling. CVC in the pulp decreased with the onset of exercise (0.53±0.09AUmmHg-1 vs. baseline 1.23±0.25AUmmHg-1, p = 0.006), and persisted low until exercise cessation, whereas CVC in the forearm started to increase at 60% of subjects' VO2max, attaining its maximum at the highest exercise load (0.44±0.11AUmmHg-1 vs. baseline 0.12±0,03AUmmHg-1, p = 0.017). In the recovery, CVC in the pulp attained a higher plateau value compared to baseline (1.51±0.22AUmmHg-1, p = 0.021), interrupted by abrupt transient falls of CVC. On the forearm, CVC subsequently returned to its baseline. SkBF of glabrous and nonglabrous sites adjust in an opposite manner to graded exercise load and also differ during recovery. [ABSTRACT FROM AUTHOR]

The purpose of this work was to integrate a new mathematical model with a bioheat model, based on physiology and first principles, to predict thermoregulatory arterio-venous anastomoses ( AVA) and cold-induced vasodilation ( CIVD) reaction to local cooling. The transient energy balance equations of body segments constrained by thermoregulatory controls were solved numerically to predict segmental core and skin temperatures, and arterial blood flow for given metabolic rate and environmental conditions. Two similar AVA- CIVD mechanisms were incorporated. The first was activated during drop in local skin temperature (<32 °C). The second mechanism was activated at a minimum finger skin temperature, T, where the AVA flow is dilated and constricted once the skin temperature reached a maximum value. The value of T was determined empirically from values reported in literature for hand immersions in cold fluid. When compared with published data, the model predicted accurately the onset time of CIVD at 25 min and T at 10 °C for hand exposure to still air at 0 °C. Good agreement was also obtained between predicted finger skin temperature and experimentally published values for repeated immersion in cold water at environmental conditions of 30, 25, and 20 °C. The CIVD thermal response was found related to core body temperature, finger skin temperature, and initial finger sensible heat loss rate upon exposure to cold fluid. The model captured central and local stimulations of the CIVD and accommodated observed variability reported in literature of onset time of CIVD reaction and T. [ABSTRACT FROM AUTHOR]

Extremely cold exposure causes human physiological changes and has implications for human health and occupational safety. In this paper, a multi-segmented human bioheat model is developed for predicting human thermoregulatory and physiological responses, especially those of the extremities, under both cold and extremely cold environments. The novel improvements in the model include: 1) the segmental energy balance equations are improved for an extended 22 human body segments; 2) the current model represents the effect of the skin perfusion blood flow on the heat conduction between the skin and core, and further considering the superficial vein blood in peripheral segments (forearms, calves, hands, feet and fingers) and modifying dimensions of the fingers, a more realistic circulatory blood flow system is implemented; 3) the thermoregulatory control equations reflecting the characteristics of human physiological responses to both cold and extremely cold exposure are implemented, including arteriovenous anastomoses (AVAs) in the extremities (feet and fingers), the local skin blood flow decreases by vasoconstriction, and the heat production by shivering. The proposed model is validated and evaluated by comparing the previous models and the published experimental data at a variety of conditions and activity. Furthermore, the experiments on human physiological responses under a range of cold exposures (−5 °C, −10 °C and −15 °C) are conducted in this study, and good agreements between the experimental data of core and skin temperatures and the predicted values of the current model are observed. [ABSTRACT FROM AUTHOR]

Purpose: To report new findings in the CHARGE syndrome with phenotypic anomalies associated with the R2319C mutation in the CHD7 gene. Methods: Fundoscopic photography, ultrasonography, fluorescein angiography, optical coherence tomography (OCT). Mutational analysis of the CHD7 gene in lymphocyte DNA. Results: Large pale optic discs with a fibrous elevation and colobomata and arterio-venous anastomoses with enlarged veins in optic discs were detected. OCT revealed numerous flat cystic spaces. The genetic study revealed the R2319C mutation in the CHD7 gene. Conclusions: The CHARGE syndrome associated with the R2319C mutation in the CHD7 gene comprised: cystic spaces in the colobomatous optic disc and intrapapillary arterio-venous anastomoses. [ABSTRACT FROM AUTHOR]

Objective: Theoretical estimates and physiological inferences suggest that the structure of a shared cotyledon differs from a non-shared cotyledon. The aim of this study was to characterise the histomorphometry of terminal villi in shared and non-shared cotyledons in monochorionic placentae, both from uncomplicated twins and from those with twin–twin transfusion syndrome (TTTS) or discordant growth restriction (ΔIUGR). Methods: Forty-one monochorionic placentae from Caucasian non-smokers were obtained at caesarean section. Their vascular anatomy and placental territories were ascertained by dye injection. After fixation, full thickness histological blocks were obtained by systematic random sampling from each twin''s territory and the shared cotyledons. Fifty randomly selected terminal villi were assessed for: (i) median villus diameter (ii) median villus capillary diameter (iii) median fetomaternal diffusion distance (iv) median no. of capillaries/villus (v) degree of vascularization (median percentage cross-sectional area of terminal villi occupied by capillaries) using a stage micrometer and image analysis programme. The histomorphometric findings were then correlated with birthweight discordance, placental territory discordance and ΔAVAs (no. of AVAs from smaller twin (donor) to larger twin (recipient) minus no. of AVAs from larger to smaller twin). Results: Histomorphometric variables were similar in shared and non-shared cotyledons of uncomplicated MCDA twins. However, the median diameter of terminal villi in shared cotyledons in ΔIUGR and TTTS placentae was significantly smaller [51.2μm (48.2–58.3), p <0.001 and 52.6μm (53.1–50.4), p <0.001], and had a similar number of smaller capillaries, larger fetomaternal diffusion distance and reduced vascularization compared to non-shared IUGR and TTTS placentae. However, Δdiameter (defined as the difference between median diameters of terminal villi in large minus small twins'' territories) rose with increasing birthweight discordance (Pearson correlation coefficient=0.82, p <0.001). Multiple linear regression analysis revealed that Δdiameter was influenced by placental territory discordance (p <0.001) and birthweight discordance (p <0.01): log10 Δdiameter=1.38+(0.01×birthweight discordance)+(0.56×log10 placental territory discordance) (R 2 =0.82, p <0.001), but there was no significant relationship with ΔAVA and AAA. In the TTTS group, Δdiameter correlated significantly with ΔAVA only: log10 Δdiameter=1.44+(0.02×ΔAVA) (R 2 =0.3, p <0.001). Conclusions: This is the first study to characterise the histomorphometry of shared and non-shared cotyledons in MC twins. The findings suggest that abnormal placentation, rather than placental vascular anatomy may be responsible for ΔIUGR in MC twins, whereas TTTS arises from imbalance in interfetal transfusion with resultant differing terminal villus histomorphometric features in donor, recipient and shared cotyledons. [Copyright &y& Elsevier]

Klippel-Trenaunay syndrome (KTS) is a rare congenital malformation of unknown etiology characterized by cutaneous hemangiomas., venous varicosities and bony and soft tissues hypertrophy usually affecting one limb. Several complex anomalies involving various organs and systems have been described, whereas involvement of the peripheral nervous system has rarely been reported in KTS. We describe the case of a 67-year-old woman with KTS and peripheral neuropathy related to the presence of epineurial microscopic arteriovenous anastomoses (AVA) and endoneurial vascular coils in sural nerve biopsy from both hypertrophic and non-hypertrophic limb. The maintenance of AVA has been proposed to be the cause of the hypertrophy. The observation in our patient of AVA in non-hypertrophic limb contrasts with this hypothesis. [ABSTRACT FROM AUTHOR]

Cold-induced vasodilation (CIVD) in the finger tips generally occurs 5-10 min after the start of local cold exposure of the extremities. This phenomenon is believed to reduce the risk of local cold injuries. However, CIVD is almost absent during hypothermia, when survival of the organism takes precedence over the survival of peripheral tissue. Subjects that are often exposed to local cold (e.g. fish filleters) develop an enhanced CIVD response. Also, differences between ethnic groups are obvious, with black people having the weakest CIVD response. Many other factors affect CIVD, such as diet, alcohol consumption, altitude, age and stress. CIVD is probably caused by a sudden decrease in the release of neurotransmitters from the sympathetic nerves to the muscular coat of the arterio-venous anastomoses (AVAs) due to local cold. AVAs are specific thermoregulatory organs that regulate blood flow in the cold and heat. Their relatively large diameter enables large amounts of blood to pass and convey heat to the surrounding tissue. Unfortunately, information on the quantity of AVAs is lacking, which makes it difficult to estimate the full impact on peripheral blood flow. This review illustrates the thermospecificity of the AVAs and the close link to CIVD. CIVD is influenced by many parameters, but controlled experiments yield information on how CIVD protects the extremities against cold injuries. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the possible mechanisms of testicular toxicity of GR40370X, a follow-up 5-hydroxytryptamine (5-HT) receptor agonist. Administration to adult male rats of a single (toxic) dose of 750 mg/kg GR40370X induced marked distension of seminiferous tubules and an associated increase in testis weight at 12–24 h with a gradual recovery to normal by 96 h. Seminiferous tubule distension was due to expansion of the lumen, which occurred at all stages of the spermatogenic cycle and was accompanied by vacuolation of the cytoplasm of elongating spermatids. Seminiferous tubule distension was preceded/accompanied by distension of the efferent ducts and rete testis with maximal changes evident at 24–48 h. These changes could not be explained by increases in seminiferous tubule fluid or interstitial fluid production, as both were reduced (15–20%), rather than increased, by treatment. Examination of the vasculature after treatment with 750 mg/kg GR40370X revealed significant changes that were maximal at 4 h and thus preceded rete/testicular changes. Veins of the mediastinal venous plexus, which overlies the rete, were constricted and arteriovenous anastomoses in the spermatic cord were shut/constricted, as determined (indirectly) by measurement of the dilution of outflowing testicular venous blood by incoming arterial blood. The latter effect of GR40370X could be blocked by co-administration of minoxidil, a vasodilator. Vascular effects of GR40370X had normalised by 24–48 h. It was also noted that administration of a toxic dose of GR40370X significantly lowered blood levels of LH and testosterone, though these changes were considered to be incidental and not involved in the other changes described above. None of the above changes were induced by a pharmacologically active dose (1 mg/kg) of GR40370X. It is concluded that the mechanism of testicular toxicity induced by 750 mg/kg GR40370X results from primary effects on the vasculature of the testis/neighbouring region, which in turn lead to impaired fluid resorption from the efferent ducts and rete and thence to accumulation of seminiferous tubule fluid in the rete and testis. [Copyright &y& Elsevier]

Presents information on a study which determined whether it is possible to identify in vivo placental arterio-venous anastomoses in monochorionic twin pregnancies by color Doppler flow mapping. Identification of normal cotyledons; Limitations of the Doppler technique.

Human spermatic cords were investigated by means of cast preparations, light-microscopic examination and computer-aided 3-dimensional reconstructions from serial sections of paraffin-embedded material. After leaving the testis, the testicular veins formed two principal groups co-existing side by side. Numerous veno-venous anastomoses could be observed within each individual group, whereas only a few mutual intergroup anastomoses were found. The testicular artery ran within one group but showed no close topographical relationship to the other group. Light microscopy of the serial sections revealed that the group of veins with no close topographical relationship to the testicular artery ran at a distance of several centimeters embedded within fatty tissue. With the help of computer-aided 3-dimensional reconstructions, a spatial picture of the vascular organization was obtained. These results allowed the following classification of the veins of the pampiniform plexus. Group-I veins formed a tight plexus around the testicular artery by means of veno-venous anastomoses. Group-II veins formed veno-venous anastomoses between each other and ran over at a sizeable distance embedded in fatty tissue but showed no close topographical relationship to the testicular artery. Group-III vessels formed veno-venous anastomoses between group-I and group-II. Group IV veins formed arterio-venous anastomoses with the testicular artery. Based on the differences in wall structure and diameter, a subclassification in group-I and group-II was undertaken. This organization of the veins of the human pampiniform plexus should further the understanding of physiological processes, such as the transfer of hormones and other substances from the veins to the testicular artery and vice versa. It should also facilitate the tracing of the veins during antegrade sclerosing. [ABSTRACT FROM AUTHOR]

The arc-capillaries represent vessels of the terminal bed; they are not true arterio-venous anastomoses. They exhibit a typical capillary structure of their wall. The existence of smooth muscle cells and modified smooth muscle cells, such as epitheloid cells, cannot be demonstrated. Likewise, a specific activation by nerves does not exist. The arc-capillaries differ from the net-capillaries neither in the structure of their wall nor in diameter. At the origin of the arc-capillaries from the final arteriole there are no smooth muscle cells, only pericytes (adventitial cells). The arc-capillaries branch off where the final arteriole no longer possesses smooth muscle cells. The electron microscopic studies showed that arc-capillaries do not represent sphincter capillaries. [ABSTRACT FROM AUTHOR]

Arterio-venous anastomoses (AVA) in gill filaments of Tilapia mossambica exhibit a distinct polarity. Two different types of highly specialized endothelial cells, both of epitheloid shape, line these vessels: Type I cells, contacting the arterial lumen, are elongated and about two to three times as large as type II endothelial cells. Their surface is increased by tentacular protrusions which reach far into the arterial lumen. Filament whorls forming tubelike structures with centrally located glycogen granules are abundant in these cells. Type II endothelial cells are located proximal to the central venous sinus (CVS). Their less abundant and more electron dense cytoplasm is free of filament whorls. There are also intermediate cell forms at approximately the middle of each anastomosis. Short cell processes protrude from all endothelial cell types into the AVA lumen. Outside the indistinct vascular basement lamina, a layer of cover cells tightly envelopes the AVA. These cells are, however, absent around the part of the AVA adjacent to the CVS. Here the endothelial cells are in immediate contact with the interstitium. Endothelial cells sheathed by cover cells reach the interstitium through basal foot processes. Nerve fibre bundles regularly come into close contact with the AVAs. Possible functions of the AVAs, including osmoreception are discussed. [ABSTRACT FROM AUTHOR]

Several studies have suggested that large-diameter (>25 μm) arterio-venous shunt pathways exist in the lungs of rats, dogs, and humans. We investigated the nature of these pathways by infusing specific-diameter fluorescent latex particles (4, 7, 15, 30, or 50 μm) into isolated, ventilated rat lungs perfused at constant pressure. All lungs received the same mass of latex (5 mg), which resulted in infused particle numbers that ranged from 1.7 × 10 7 4 μm particles to 7.5 × 10 4 50 μm particles. Particles were infused over 2 min. We used a flow cytometer to count particle appearances in venous effluent samples collected every 0.5 min for 12 min from the start of particle infusion. Cumulative percentages of infused particles that appeared in the samples averaged 3.17 ± 2.46% for 4 μm diameter particles, but ranged from 0.01% to 0.17% for larger particles. Appearances of 4 μm particles followed a rapid upslope beginning at 30 sec followed by a more gradual downslope that lasted for up to 12 min. All other particle diameters also began to appear at 30 sec, but followed highly irregular time courses. Infusion of 7 and 15 μm particles caused transient but significant perfusate flow reductions, while infusion of all other diameters caused insignificant reductions in flow. We conclude that small numbers of bypass vessels exist that can accommodate particle diameters of 7-to-50 μm. We further conclude that our 4 μm particle data are consistent with a well-developed network of serial and parallel perfusion pathways at the acinar level., (Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)