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Renal ischemia-reperfusion (I/R) injury results in damage to the renal tubules and causes impairments in sodium [Na + ] reabsorption. Given the inability to conduct mechanistic renal I/R injury studies in vivo in humans, eccrine sweat glands have been proposed as a surrogate model given the anatomical and physiological similarities. We tested the hypothesis that sweat Na + concentration is elevated following I/R injury during passive heat stress. We also tested the hypothesis that I/R injury during heat stress will impair cutaneous microvascular function. Fifteen young healthy adults completed ∼160 min of passive heat stress using a water-perfused suit (50°C). At 60 min of whole body heating, one upper arm was occluded for 20 min followed by a 20-min reperfusion. Sweat was collected from each forearm via an absorbent patch pre- and post-I/R. Following the 20-min reperfusion, cutaneous microvascular function was measured via local heating protocol. Cutaneous vascular conductance (CVC) was calculated as red blood cell flux/mean arterial pressure and normalized to CVC during local heating to 44°C. Na + concentration was log-transformed and data were reported as a mean change from pre-I/R (95% confidence interval). Changes in sweat sodium concentration from pre-I/R differed between arms post-I/R (experimental arm: +0.97 [+0.67 - 1.27] [LOG] Na + ; control arm: +0.68 [+0.38 - 0.99] [LOG] Na + ; P < 0.01). However, CVC during the local heating was not different between the experimental (80 ± 10% max ) and control arms (78 ± 10% max ; P = 0.59). In support of our hypothesis, Na + concentration was elevated following I/R injury, but likely not accompanied by alterations in cutaneous microvascular function. NEW & NOTEWORTHY In the present study, we have demonstrated that sweat sodium concentration is elevated following ischemia-reperfusion injury during passive heat stress. This does not appear to be mediated by reductions in cutaneous microvascular function or active sweat glands, but may be related to alterations in local sweating responses during heat stress. This study demonstrates a potential use of eccrine sweat glands to understand sodium handling following ischemia-reperfusion injury, particularly given the challenges of in vivo studies of renal ischemia-reperfusion injury in humans.

Skin-interfaced microfluidic systems help assess health status and chemical exposure.

Hematohidrosis is an uncommon pathophysiological condition of sweating blood. A young lady with abrupt bleeding from the skin (since January 2017) was brought to the emergency. The bleeding was vanished after mopping with no site of injury, but it reappeared soon enough confirming its nature. Bleeding time (BT), clotting time (CT), and the prothrombin time (PT) was within normal limit. This patient is confirmed as a case of hematohidrosis by the method of exclusion and the presence of blood was finalized by benzidine test as well as biochemical and microscopic examination of it. Now, no treatment is available as per the latest pieces of evidence. Also, the cause of it is not known till date. Psychological anxiety is a predisposing cause for hematohidrosis., (© Journal of the Association of Physicians of India 2011.)

Objective: Most methods for monitoring sweat gland activity use simple gravimetric methods, which merely measure the average sweat rate of multiple sweat glands over a region of skin. It would be extremely useful to have a method which could quantify individual gland activity in order to improve the treatment of conditions which use sweat tests as a diagnostic tool, such as hyperhidrosis, cystic fibrosis, and peripheral nerve degeneration., Methods: An optical method using an infrared camera to monitor the skin surface temperature was developed. A thermodynamics computer model was then implemented to utilize these skin temperature values along with other environmental parameters, such as ambient temperature and relative humidity, to calculate the sweat rates of individual glands using chemically stimulated and unstimulated sweating. The optical method was also used to monitor sweat pulsation patterns of individual sweat glands., Results: In this preliminary study, the feasibility of the optical approach was demonstrated by measuring sweat rates of individual glands at various bodily locations. Calculated values from this method agree with expected sweat rates given values found in literature. In addition, a lack of pulsatile sweat expulsion was observed during chemically stimulated sweating, and a potential explanation for this phenomenon was proposed., Conclusion: A simple, non-contact optical method to quantify sweat gland activity in-vivo was presented., Significance: This method allows researchers and clinicians to investigate several sweat glands simultaneously, which has the potential to provide more accurate diagnoses and treatment as well as increase the potential utility for wearable sweat sensors.

Wearable sensors to monitor human sweat loss are important for real-time health monitoring, requiring electrically conductive, mechanically flexible fabrics as working electrodes. Here, a textile-based sweat monitor was fabricated by screen printing of carbon black and recycled sericin on cotton fabrics. The obtained fabric with excellent flexibility, good hydrophilicity (86°), and proper resistivity (61.7 Ω/cm 2 ) can be used as a working electrode for a wearable sweat monitor. A wearable sweat monitor is highly sensitive (42.7% in acidic sweat), flexible, and can be washed (99.1% retention after 30 washes). This work offers a promising approach for the fabrication of wearable sensors and promotes the widespread applications of personalized health-monitoring devices.

Herein, we develop a novel smart cotton swab as a diagnostic assay for onsite monitoring of sweat pH changes toward potential applications in monitoring human healthcare and drug exam. Anthocyanin (Ac) can be extracted from Brassica oleracea var. capitata f. rubra using a simple procedure. Then, it can be used as a direct dye into cotton fibers using potash alum as mordant (M) to fix the anthocyanin dye onto the surface of the cotton fabric (Cot). This was monitored by generating mordant/anthocyanin nanoparticles (MAcNPs) onto the fabric surface. The cotton sensor assay demonstrated colorimetric changes in the ultraviolet-visible absorbance spectral analysis associated with a blueshift from 588 to 422 nm with increasing the pH of a perspiration simulant fluid. The biochromic performance of the dyed cotton diagnostic assay depended essentially on the halochromic activity of the anthocyanin spectroscopic probe to demonstrate a color change from pink to green due to intramolecular charge transfer occurring on the anthocyanin chromophore. After dyeing, no significant defects were detected in air-permeability and bend length. High colorfastness was investigated for the dyed cotton fabrics., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A well-documented phenomenon among social insects is that brain changes occur prior to or at the onset of certain experiences, potentially serving to prime the brain for specific tasks. This insight comes almost exclusively from studies considering developmental maturation in females. As a result, it is unclear whether age-related brain plasticity is consistent across sexes, and to what extent developmental patterns differ. Using confocal microscopy and volumetric analyses, we investigated age-related brain changes coinciding with sexual maturation in the males of the facultatively eusocial sweat bee, Megalopta genalis, and the obligately eusocial bumble bee, Bombus impatiens. We compared volumetric measurements between newly eclosed and reproductively mature males kept isolated in the lab. We found expansion of the mushroom bodies-brain regions associated with learning and memory-with maturation, which were consistent across both species. This age-related plasticity may, therefore, play a functionally-relevant role in preparing male bees for mating, and suggests that developmentally-driven neural restructuring can occur in males, even in species where it is absent in females., (© 2021. The Author(s).)

While the printed circuit board (PCB) has been widely considered as the building block of integrated electronics, the world is switching to pursue new ways of merging integrated electronic circuits with textiles to create flexible and wearable devices. Herein, as an alternative for PCB, we described a non-printed integrated-circuit textile (NIT) for biomedical and theranostic application via a weaving method. All the devices are built as fibers or interlaced nodes and woven into a deformable textile integrated circuit. Built on an electrochemical gating principle, the fiber-woven-type transistors exhibit superior bending or stretching robustness, and were woven as a textile logical computing module to distinguish different emergencies. A fiber-type sweat sensor was woven with strain and light sensors fibers for simultaneously monitoring body health and the environment. With a photo-rechargeable energy textile based on a detailed power consumption analysis, the woven circuit textile is completely self-powered and capable of both wireless biomedical monitoring and early warning. The NIT could be used as a 24/7 private AI "nurse" for routine healthcare, diabetes monitoring, or emergencies such as hypoglycemia, metabolic alkalosis, and even COVID-19 patient care, a potential future on-body AI hardware and possibly a forerunner to fabric-like computers., (© 2021. The Author(s).)

The body naturally and continuously secretes sweat for thermoregulation during sedentary and routine activities at rates that can reflect underlying health conditions, including nerve damage, autonomic and metabolic disorders, and chronic stress. However, low secretion rates and evaporation pose challenges for collecting resting thermoregulatory sweat for non-invasive analysis of body physiology. Here we present wearable patches for continuous sweat monitoring at rest, using microfluidics to combat evaporation and enable selective monitoring of secretion rate. We integrate hydrophilic fillers for rapid sweat uptake into the sensing channel, reducing required sweat accumulation time towards real-time measurement. Along with sweat rate sensors, we integrate electrochemical sensors for pH, Cl - , and levodopa monitoring. We demonstrate patch functionality for dynamic sweat analysis related to routine activities, stress events, hypoglycemia-induced sweating, and Parkinson's disease. By enabling sweat analysis compatible with sedentary, routine, and daily activities, these patches enable continuous, autonomous monitoring of body physiology at rest.

New Findings: What is the central question to this study? Do the sweat glands' maximum ion reabsorption rates increase following heat acclimation in healthy older individuals and is this associated with elevated aldosterone concentrations? What is the main finding and its importance? Sweat gland maximum ion reabsorption rates improved heterogeneously across body sites, which occurred without any changes in aldosterone concentration following a controlled hyperthermic heat acclimation protocol in healthy older individuals., Abstract: We examined whether the eccrine sweat glands' ion reabsorption rates improved following heat acclimation (HA) in older individuals. Ten healthy older adults (>65 years) completed a controlled hyperthermic (+0.9°C rectal temperature, T re ) HA protocol for nine non-consecutive days. Participants completed a passive heat stress test (lower leg 42°C water submersion) pre-HA and post-HA to assess physiological regulation of sweat gland ion reabsorption at the chest, forearm and thigh. The maximum ion reabsorption rate was defined as the inflection point in the slope of the relation between galvanic skin conductance and sweat rate (SR). We explored the responses again after a 7-day decay. During passive heating, the T b thresholds for sweat onset on the chest and forearm were lowered after HA (P < 0.05). However, sweat sensitivity (i.e. the slope), the SR at a given T re and gross sweat loss did not improve after HA (P > 0.05). Any changes observed were lost during the decay. Pilocarpine-induced sudomotor responses to iontophoresis did not change after HA (P ≥ 0.801). Maximum ion reabsorption rate was only enhanced at the chest (P = 0.001) despite unaltered aldosterone concentration after HA. The data suggest that this adaptation is lost after 7 days' decay. The HA protocol employed in the present study induced partial adaptive sudomotor responses. Eccrine sweat gland ion reabsorption rates improved heterogeneously across the skin sites. It is likely that aldosterone secretion did not alter the chest sweat ion reabsorption rates observed in the older adults., (© 2020 The Authors. Experimental Physiology © 2020 The Physiological Society.)

Excessive stress is one of the main causes of mental illness. Long-term exposure of stress could affect one's physiological wellbeing (such as hypertension) and psychological condition (such as depression). Multisensory information such as heart rate variability (HRV) and pH can provide suitable information about mental and physical stress. This paper proposes a novel approach for stress condition monitoring using disposable flexible sensors. By integrating flexible amplifiers with a commercially available flexible polyvinylidene difluoride (PVDF) mechanical deformation sensor and a pH-type chemical sensor, the proposed system can detect arterial pulses from the neck and pH levels from sweat located in the back of the body. The system uses organic thin film transistor (OTFT)-based signal amplification front-end circuits with modifications to accommodate the dynamic signal ranges obtained from the sensors. The OTFTs were manufactured on a low-cost flexible polyethylene naphthalate (PEN) substrate using a coater capable of Roll-to-Roll (R2R) deposition. The proposed system can capture physiological indicators with data interrogated by Near Field Communication (NFC). The device has been successfully tested with healthy subjects, demonstrating its feasibility for real-time stress monitoring.

Humans, like other animals, have an excellent sense of smell that can serve social communication. Although ample research has shown that body odours can convey transient emotions like fear, these studies have exclusively treated emotions as categorical , neglecting the question whether emotion quantity can be expressed chemically. Using a unique combination of methods and techniques, we explored a dose-response function: Can experienced fear intensity be encoded in fear sweat? Specifically, fear experience was quantified using multivariate pattern classification (combining physiological data and subjective feelings with partial least-squares-discriminant analysis), whereas a photo-ionization detector quantified volatile molecules in sweat. Thirty-six male participants donated sweat while watching scary film clips and control (calming) film clips. Both traditional univariate and novel multivariate analysis (100% classification accuracy; Q 2 : 0.76; R 2 : 0.79) underlined effective fear induction. Using their regression-weighted scores, participants were assigned significantly above chance (83% > 33%) to fear intensity categories (low-medium-high). Notably, the high fear group ( n = 12) produced higher doses of armpit sweat, and greater doses of fear sweat emitted more volatile molecules ( n = 3). This study brings new evidence to show that fear intensity is encoded in sweat (dose-response function), opening a field that examines intensity coding and decoding of other chemically communicable states/traits. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

Purpose of Review: There has been an increasing interest in developing novel technologies to treat patients with chronic kidney disease as evidenced by KidneyX, the public-private partnership between government and industry. Perhaps a simple technology for treating kidney failure would be to utilize perspiration. It is a physiological process, and when used properly it might not be an unpleasant experience. This review will explore the current state of knowledge regarding perspiration therapy in the setting of far advanced kidney failure., Recent Findings: A literature review using the PubMed database was conducted between 1 April 2019 and 3 September 2019. Search terms are shown in Table 1. Major themes of the results include diaphoresis therapy for patients with chronic kidney disease, excessive perspiration causing kidney disease, analysis of sweat to diagnose cystic fibrosis, and analysis of sweat to replenish lost electrolytes. This review will focus on intentional perspiration for the treatment of patients with end-stage renal disease (ESRD). Studies have shown that perspiration, or sweat-based therapies, can provide some of the most important currently recognized therapeutic goals in treating ESRD. These goals include decreased interdialytic weight gain, reduced serum potassium levels, and benefits to cardiovascular status. Research has shed light on some of the mechanisms, both molecular and clinical, that may be involved in induced perspiration therapy in ESRD., Summary: There is a long history of humans using perspiration for both recreation and therapy. Perspiration therapy for ESRD experienced a surge in the United States in the 1960s but does not have much modern momentum. With the continued growth of the ESRD population worldwide this could be considered an appropriate time to conduct more research into this promising therapy.

This study reports a microfluidic chip-based wearable colorimetric sensor for detecting sweat glucose. The device consisted of five microfluidic channels branching out from the center and connected to the detection microchambers. The microchannels could route the sweat excreted from the epidermis to the microchambers, and each of them was integrated with a check valve to avoid the risk of the backflow of the chemical reagents from the microchamber. The microchambers contained the pre-embedded glucose oxidase (GOD)-peroxidase- o -dianisidine reagents for sensing the glucose in sweat. It was found that the color change caused by the enzymatic oxidation of o -dianisidine could show a more sensitive response to the glucose than that of the conventional GOD-peroxidase-KI system. This sensor could perform five parallel detections at one time. The obtained linear range for sweat glucose was 0.1-0.5 mM with a limit of detection of 0.03 mM. The sensor was also used to detect the glucose in sweat samples from a group of subjects engaged in both fasting and postprandial trials. The results showed that our wearable colorimetric sensor can reveal the subtle differences existing in the sweat glucose concentration after the fasting and the oral glucose uptake.

Sweating plays an important role in maintaining temperature homeostasis in humans. However, under certain circumstances, sweat can cause itching. For example, when excessive sweat accumulates on the skin surface for a long period, miliaria can develop and cause itching. Subjects with dermatoses, such as atopic dermatitis (AD), suffer from itch when exposed to heat or psychological stresses, which are also known perspiration stimuli. Recently, some mechanisms of sweat-induced itch have been revealed. For instance, attenuated sweating ability is observed in subjects with AD, causing heat retention, skin dryness, and high susceptibility to itch. Furthermore, the decreased tight junction of the sweat gland in AD leads to sweat leakage in the dermis, which could be designated as a "sweat endocrine response" and may be the cause of tingling itch during sweating. Additionally, metabolomic analysis of sweat from patients with AD revealed that glucose concentration in sweat increases according to disease severity. Sweat with elevated glucose concentration retards the recovery of the damaged skin barrier and may promote itching. This viewpoint essay outlines the relationship between sweat and itch based on recent evidence., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The fabrication and performance of a wearable paper-based chemiresistor for monitoring perspiration dynamics (sweat rate and sweat loss) are detailed. A novel approach is introduced to measure the amount of aqueous solution in the order of microliters delivered to the sensor by monitoring a linear change in resistance along a conducting paper. The wearable sensor is based on a single-walled carbon nanotubes and surfactant (sodium dodecylbenzenesulfonate) nanocomposite integrated within cellulose fibers of a conventional filter paper. The analytical performance and the sensing mechanism are presented. Monitoring sweat loss in the human body while exercising is demonstrated using the integration of a wireless reader and a user-friendly interface. By addressing the barriers of cost, simplicity, and the truly in situ demanding measurements, this unique wearable sensor is expected to serve in the future in many different applications involving the on-body detection of biofluids, such as a monitoring tool of dehydration levels for athletes as well as a tool for enhancing the sport performance by providing an accurate recovery of the hydration status in daily exercises., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objective: To assess the diagnostic value of sweat conductivity testing in Chinese children with cystic fibrosis (CF). Methods: This is a retrospective study. Sweat conductivity tests were conducted in 45 CF children (CF group) and 200 non-CF children (non-CF group) diagnosed with other chronic pulmonary diseases at the No. 2 Department of Respiratory Medicine, Beijing Children's Hospital from May 2014 to June 2018. Pearson's chi-square test was used to assess the differences between CF and non-CF groups. A receiver operating characteristic curve was constructed to calculate the best cut-off value to diagnose or rule out CF. The pulmonary function parameters (forced expiratory volume in the first second, forced vital capacity,forced expiratory flows at 75% of exhaled vital capacity) of CF children over 6 years old were analyzed. The relationship between sweat conductivity and pulmonary function was compared between the two groups (80-120mmol/L vs .>120mmol/L). Results: The age of CF group was 9 (7,12) years old, 19 males (42%) and 26 females(58%); the age of non-CF group was 8 (5,11) years old, 106 males (53%) and 94 females(47%). The results of sweat conductivity test showed that sweat conductivity in CF group 108(99, 122) mmol/L was significantly higher than that in non-CF group 43(36, 52) mmol/L (χ(2)=207, P< 0.01). A cut-off value of 80 mmol/L for CF diagnosis showed a sensitivity of 93.3% and a specificity of 98.5%. The receiver operating characteristic curve analysis suggested the best conductivity cut-off value for the diagnosis of CF was at 83.5 mmol/L,with a sensitivity of 93.3% and a specificity of 100%,and an area under the curve of 0.993 (95% confidence interval 0.985-1.000). The best conductivity cut-off value to rule out CF diagnosis was at 63.5 mmol/L,with a sensitivity of 97.8% and a specificity of 90.5%. There was no correlation between the level of sweat conductivity and the extent of pulmonary function decline. Conclusions: Sweat conductivity testing can be used for the screening of CF in Chinese children. A diagnosis of CF should be considered if the value is greater than 80 mmol/L.

New Findings: What is the central question of this study? Are ultraviolet radiation (UVR)-induced increases in skin blood flow independent of skin erythema? Does broad-spectrum UVR exposure attenuate NO-mediated cutaneous vasodilatation, and does sunscreen or sweat modulate this response? What are the main findings and their importance? Erythema and vascular responses to UVR are temporally distinct, and sunscreen prevents both responses. Exposure to UVR attenuates NO-mediated vasodilatation in the cutaneous microvasculature; sunscreen or simulated sweat on the skin attenuates this response. Sun over-exposure may elicit deleterious effects on human skin that are separate from sunburn, and sunscreen or sweat on the skin may provide protection., Abstract: Exposure to ultraviolet radiation (UVR) may result in cutaneous vascular dysfunction independent of erythema (skin reddening). Two studies were designed to differentiate changes in erythema from skin vasodilatation throughout the 8 h after acute broad-spectrum UVR exposure with (+SS) or without SPF-50 sunscreen (study 1) and to examine NO-mediated cutaneous vasodilatation after acute broad-spectrum UVR exposure with or without +SS or simulated sweat (+SW) on the skin (study 2). In both studies, laser-Doppler flowmetry was used to measure red cell flux, and cutaneous vascular conductance (CVC) was calculated (CVC = flux/mean arterial pressure). In study 1, in 14 healthy adults (24 ± 4 years old; seven men and seven women), the skin erythema index and CVC were measured over two forearm sites (UVR only and UVR+SS) before, immediately after and every 2 h for 8 h post-exposure (750 mJ cm -2 ). The erythema index began to increase immediately post-UVR (P < 0.05 at 4, 6 and 8 h), but CVC did not increase above baseline for the first 4-6 h (P ≤ 0.01 at 6 and 8 h); +SS prevented both responses. In study 2, in 13 healthy adults (24 ± 4 years old; six men and seven women), three intradermal microdialysis fibres were placed in the ventral skin of the forearm [randomly assigned to UVR (450 mJ cm -2 ), UVR+SS or UVR+SW], and one fibre (non-exposed control; CON) was placed in the contralateral forearm. After UVR, a standardized local heating (42°C) protocol quantified the percentage of NO-mediated vasodilatation (%NO). The UVR attenuated %NO compared with CON (P = 0.01). The diminished %NO was prevented by +SS (P < 0.01) and +SW (P < 0.01). Acute broad-spectrum UVR attenuates NO-dependent dilatation in the cutaneous microvasculature, independent of erythema. Sunscreen protects against both inflammatory and heating-induced endothelial dysfunction, and sweat might prevent UVR-induced reductions in NO-dependent dilatation., (© 2019 The Authors. Experimental Physiology © 2019 The Physiological Society.)

Wearable technologies will play an important role in advancing precision medicine by enabling measurement of clinically-relevant parameters describing an individual's health state. The lifestyle and fitness markets have provided the driving force for the development of a broad range of wearable technologies that can be adapted for use in healthcare. Here we review existing technologies currently used for measurement of the four primary vital signs: temperature, heart rate, respiration rate, and blood pressure, along with physical activity, sweat, and emotion. We review the relevant physiology that defines the measurement needs and evaluate the different methods of signal transduction and measurement modalities for the use of wearables in healthcare.

The aim of the study was to determine the effect of gender, body mass index, and time on the width of friction ridge impressions in fingerprints and the content of sweat and sebum forming the print. The research showed that the friction ridge impressions of women are significantly wider than those of men, and this tendency persists throughout the existence of the print. The differences may result from the anatomical structure of the skin, as well as from the use of protective products such as creams, which are used more often by women. The width of friction ridge impression is similar in underweight and overweight people, but greater than in those with normal body weight, and the amount of sweat and sebum increases with body weight. The passage of time significantly reduces both the width of the friction ridge impression and the content of sweat and sebum secretions in the print., (© 2018 American Academy of Forensic Sciences.)

Objective: The aim of this study was to report a method that quantifies axon reflex sweating from individual sweat glands with nanoliter precision. Measurement of the axon reflex is generally expressed as a single variable (e.g., the flare area or total sweat volume). High-definition videography enables precise measurement of sweating from single, axon reflex-stimulated sweat glands (SGs)., Methods: The sudomotor axon reflex was activated in healthy subjects and subjects with peripheral neuropathy by iontophoresis of 10% acetylcholine. Sweating was simultaneously imaged for 5 min in a 2.5-cm 2 area of iodine-coated skin to one side of the stimulus, using a customized high-resolution camera with starch-coated transparent tape over a rigid viewing screen. A second video then imaged the directly stimulated sweating. The indirect sweat response was quantified in terms of sweat gland number and distance from the stimulation site (radius), sweat rate per gland, and total sweat., Results: Fifty-two healthy control and twenty subjects with neuropathy underwent testing at the foot, calf, thigh, and hand. Normal ranges were calculated for SG density, mean sweat rate per SG, and total sweat volume. Neuropathy subjects demonstrated reduced sweating, and values differed between body sites., Interpretation: The described method precisely measures the total and individual sweat output of hundreds of SGs in response to a standard, axon reflex-mediated stimulus, and quantifies alterations in axon reflex sweating seen in peripheral neuropathy.

Accumulating evidence has pointed to a human capacity to communicate emotions to others via sweat. So far, these studies have relied exclusively on Western Caucasian samples. Our aim was to test whether the chemosensory communication of emotions extended beyond ethno-cultural boundaries, from Western Caucasians (N = 48) to East Asians (N = 48). To test this, we used well-validated materials and procedures, a double-blind design, a pre-registered analysis plan, and a combination of facial electromyography (EMG) and continuous flash suppression techniques to measure unconscious emotions. Our results show that East Asian (and Western Caucasian) female receivers exposed to the sweat (body odor) of fearful, happy, and neutral Western Caucasian male senders emulate these respective states based on body odors, outside of awareness. More specifically, East Asian (and Western Caucasian) receivers demonstrated significantly different patterns of facial muscle activity when being exposed to fear odor, happy odor, and neutral odor. Furthermore, fear odor decreased the suppression time of all faces on an interocular suppression task (IST), indicating subconscious vigilance, whereas happy odor increased the detection speed of happy faces. These combined findings suggest that the ability to perceive emotional signals from body odor may be a universal phenomenon., (Copyright © 2018. Published by Elsevier Ltd.)

Choosing food is not a trivial decision that people need to make daily, which is often subject to social influences. Here, we studied a human homolog of social transmission of food preference (STFP) as observed in rodents and other animals via chemosignals of body secretions. Human social chemosignals (sweat) produced during a disgust or neutral state among a group of donors were presented to participants undergoing a 2-alternative-forced-choice food healthiness judgment task during functional magnetic resonance imaging (fMRI). Response speed and two key signal detection indices-d' (discrimination sensitivity) and β (response bias)-converged to indicate that social chemosignals of disgust facilitated food healthiness decisions, in contrast to primary disgust elicitors (disgust odors) that impaired the judgment. fMRI analyses (disgust vs. neutral sweat) revealed that the fusiform face area (FFA), amygdala, and orbitofrontal cortex (OFC) were engaged in processing social chemosignals of disgust during food judgment. Importantly, a double contrast of social signaling across modalities (olfactory vs. visual-facial expressions) indicated that the FFA and OFC exhibited preferential response to social chemosignals of disgust. Together, our findings provide initial evidence for human STFP, where social chemosignals are incorporated into food decisions by engaging social and emotional areas of the brain.

Individual perspiration level indicates a person's physical status as well as their comfort level. Therefore, continuous perspiration level measurement enables people to monitor these conditions for applications including fitness assessment, athlete physical status monitoring, and patient/elderly care. Prior work on perspiration (sweat) sensing required the user either to be static or to wear the adhesive sensor directly on the skin, which limits users' mobility and comfort. In this paper, we present a novel conductive thread-based textile sensor that measures an individual's on-cloth sweat quantity. The sensor consists of three conductive threads. Each conductive thread is surrounded by a braided cotton cover. An additional braided cotton cover is placed outside the three conductive threads, holding them in a position that is stable for measurement. the sensor can be embedded at various locations on a person's clothing. When the person sweats, the cotton braids absorb the sweat and change the conductivity (resistance) between conductive threads. We used a voltage dividing circuit to measure this resistance as the sensor output (DC). We then conducted a sensor calibration to map this measured voltage to the quantity of electrolyte solution (with the same density as sweat) applied to the sensor. We used this sensor to measure individuals' perspiration quantity and infer their perceived perspiration levels. The system is able to limit the average prediction error to 0.4 levels when compared to five pre-defined perceived perspiration levels.

Sweat is a transparent hypotonic body fluid made from eccrine sweat glands. Various ingredients contained in sweat are involved in a broad sense in skin homeostasis including temperature regulation, skin moisture, and immune functions. Thus, sweat plays a major role in maintaining skin homeostasis. Therefore, abnormal sweating easily compromises human health. For example, in atopic dermatitis (AD), perspiration stagnation accompanying sweat tube or sweat pore blockage, leakage of perspiration from the sweat gland to the outside tissue, and impaired secretion of sweat from the sweat gland are confirmed. In recent years, the hypothesis that atopic dermatitis is a sweat stasis syndrome has been clarified by the establishment of a sweat and sweat gland dynamic analysis technique. Secretion of sweat and leakage into tissues is caused by dermatitis and is thought to promote itching. Furthermore, from the metabolomic analysis of sweat of patients with atopic dermatitis, it was confirmed that the glucose concentration in AD sweat increased according to severity and skin phenotype, suggesting that elevated glucose affected the homeostasis of the skin. Multifaceted analyses of sweat from subjects with AD have revealed new aspects of the pathology, and appropriate measures to treat sweat can be expected to contribute to long-term control of AD., (Copyright © 2018 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.)

Background: Fluid intake during military training is prescribed based on the interactions among work rates, environmental conditions, and uniform configurations. The efficacy of this guidance has not been empirically assessed in over a decade. To determine the acceptability of the fluid intake guidance, sweat losses were measured in a variety of conditions with modern uniform/body armor configurations and were then compared to prescribed fluid intakes for each condition (workload, environment, clothing)., Methods: Whole body sweat losses of 324 Soldiers and 14 model simulations were measured under a variety of work intensities ((Watts) easy, moderate, hard), work durations (2-25 h), environmental conditions (White-Black flag), and uniform configurations (including Army Combat Uniform and body armor). Whole body sweat losses were then calculated relative to 4 h drinking guidance and in accordance with TB MED 507 recommended work/rest ratios. The differences between the prescribed fluid intake and sweat loss were calculated and expressed as a percent loss or gain of body weight. Values within a threshold of ±2% body water flux (BWF) were deemed an acceptable conservative starting point for performance and health concerns., Findings: Values within ±2% BWF numbered 309/338; 25 of 338 observations exceeded the +2% BWF while 4 of 338 observations exceeded the -2% BWF. When total fluid restriction was simulated, all experienced body weight loss with 151 of 338 observations exceeding the -2% BWF., Discussion: When calculated using actual measured sweating rates from the laboratory and model simulations, current fluid intake guidance appears to predict with 91.4% accuracy the volume of fluid required to maintain a proper euhydrated state (±2%) during 4 h of exercise. Simulations of total fluid restriction support the necessity for fluid intake guidance so that the Warfighter's performance does not degrade. It is recommended that the current military fluid intake guidance focuses on methods for accurately tracking fluid intakes., (Published by Oxford University Press on behalf of Association of Military Surgeons of the United States 2018.)

By combining galvanic skin conductance (GSC), stratum corneum hydration (HYD) and regional surface sweat rate (RSR) measurements at the arm, thigh, back and chest, we closely monitored the passage of sweat from gland to skin surface. Through a varied exercise-rest protocol, sweating was increased slowly and decreased in 16 male and female human participants (25.3 ± 4.7 yr, 174.6 ± 10.1 cm, 71.3 ± 12.0 kg, 53.0 ± 6.8 ml·kg -1 ·min -1 ). ∆GSC and HYD increased before RSR, indicating pre-secretory sweat gland activity and skin hydration. ∆GSC and HYD typically increased concomitantly during rest in a warm environment (30.1 ± 1.0°C, 30.0 ± 4.7% relative humidity) and only at the arm did ∆GSC increase before an increase in HYD. HYD increased before RSR, before sweat was visible on the skin, but not to full saturation, contradicting earlier hypotheses. Maximal skin hydration did occur, as demonstrated by a plateau in all regions. Post exercise rest resulted in a rapid decrease in HYD and RSR but a delayed decline in ∆GSC. Evidence for reabsorption of surface sweat into the skin following a decline in sweating, as hypothesized in the literature, was not found. This suggests that skin surface sweat, after sweating is decreased, may not diffuse back into the dermis, but is only evaporated. These data, showing distinctly different responses for the three measured variables, provide useful information about the fate of sweat from gland to surface that is relevant across numerous research fields (e.g., thermoregulation, dermatology, ergonomics and material design). NEW & NOTEWORTHY After sweat gland stimulation, sweat travels through the duct, penetrating the epidermis before appearing on the skin surface. We found that only submaximal stratum corneum hydration was required before surface sweating occurred. However, full hydration occurred only once sweat was on the surface. Once sweating reduces, surface sweat evaporation continues, but there is a delayed drying of the skin. This information is relevant across various research fields, including environmental ergonomics, dermatology, thermoregulation, and skin-interface interactions.

This study determined the relations between regional (REG) and whole body (WB) sweating rate (RSR and WBSR, respectively) as well as REG and WB sweat Na + concentration ([Na + ]) during exercise. Twenty-six recreational athletes (17 men, 9 women) cycled for 90 min while WB sweat [Na + ] was measured using the washdown technique. RSR and REG sweat [Na + ] were measured from nine regions using absorbent patches. RSR and REG sweat [Na + ] from all regions were significantly ( P < 0.05) correlated with WBSR ( r = 0.58-0.83) and WB sweat [Na + ] ( r = 0.74-0.88), respectively. However, the slope and y-intercept of the regression lines for most models were significantly different than 1 and 0, respectively. The coefficients of determination ( r 2 ) were 0.44-0.69 for RSR predicting WBSR [best predictors: dorsal forearm ( r 2  = 0.62) and triceps ( r 2  = 0.69)] and 0.55-0.77 for REG predicting WB sweat [Na + ] [best predictors: ventral forearm ( r 2  = 0.73) and thigh ( r 2  = 0.77)]. There was a significant ( P < 0.05) effect of day-to-day variability on the regression model predicting WBSR from RSR at most regions but no effect on predictions of WB sweat [Na + ] from REG. Results suggest that REG cannot be used as a direct surrogate for WB sweating responses. Nonetheless, the use of regression equations to predict WB sweat [Na + ] from REG can provide an estimation of WB sweat [Na + ] with an acceptable level of accuracy, especially using the forearm or thigh. However, the best practice for measuring WBSR remains conventional WB mass balance calculations since prediction of WBSR from RSR using absorbent patches does not meet the accuracy or reliability required to inform fluid intake recommendations. NEW & NOTEWORTHY This study developed a body map of regional sweating rate and regional (REG) sweat electrolyte concentrations and determined the effect of within-subject (bilateral and day-to-day) and between-subject (sex) factors on the relations between REG and the whole body (WB). Regression equations can be used to predict WB sweat Na + concentration from REG, especially using the forearm or thigh. However, prediction of WB sweating rate from REG sweating rate using absorbent patches does not reach the accuracy or reliability required to inform fluid intake recommendations.

Following exercise, mean arterial pressure (MAP) is reduced ~5-10 mmHg from preexercise baseline. In nonendurance-trained males, postexercise hypotension results from peripheral vasodilation not offset by increased cardiac output (CO). By contrast, postexercise hypotension occurs through a reduction in CO from preexercise baseline in endurance-trained males. The reason(s) explaining these divergent responses remain unknown. Exercise at fixed percentage of peak oxygen consumption (V̇o 2peak ) is associated with a greater rate of metabolic heat production in trained individuals and therefore elevated sweat rates, both when compared with untrained individuals. We hypothesized that greater fluid loss would explain the postexercise reduction in CO of endurance-trained males. Twelve endurance-trained males (Trained: V̇o 2peak , 64 ± 5 ml O 2 ·kg -1 ·min -1 ) cycled for 60 min at 60% V̇o 2peak (Trained 60% ). On separate days, 12 nonendurance trained males (Untrained: V̇o 2peak , 49 ± 3 ml O 2 ·kg -1 ·min -1 ) cycled at 1) 60% V̇o 2peak (Untrained 60% ), and 2) a rate of heat production equivalent to that achieved by the Trained group (Untrained Matched ). Fluid loss was similar between Trained 60% (-1.32 ± 0.20 kg) and Untrained Matched (-1.32 ± 0.23 kg; P = 0.99) but was greater in these conditions relative to Untrained 60% (-0.95 ± 0.11 kg; both P < 0.01). During the final 30 min of postexercise supine recovery, MAP was similarly reduced by 5 ± 2 mmHg in all three conditions ( P = 0.91). The reduction in MAP was mediated by a 0.5 ± 0.3 l/min reduction in CO from baseline in Trained 60% ( P = 0.01). In contrast, CO returned to baseline following exercise during Untrained Matched and Untrained 60% (both P ≥ 0.30). These data demonstrate that greater fluid loss does not fully explain the divergent postexercise hemodynamic responses observed in trained relative to untrained males. NEW & NOTEWORTHY Even when matched for exercise-induced fluid loss, cardiac output was decreased in trained males but returned to baseline following exercise in their untrained counterparts. However, as per our hypothesis, reductions in stroke volume were similar between groups. This suggests that exercise-induced fluid loss is an important determinant of the stroke volume response during recovery but factors affecting heart rate such as exercise intensity and/or heat stress are also important determinants of postexercise hemodynamics.

Skin barrier dysfunction is inherent to atopic dermatitis (AD), causing dryness, irritation, and increased permeability to irritants, allergens and pathogens. Eccrine sweat functions as part of the skin's protective barrier. Variations in sweat responses have been observed in patients with AD, and altered sweat composition and dynamics are under-recognized as important factors in the disease cycle. This review discusses the role that sweat plays in the pathogenesis of AD, examines evidence on abnormal sweat composition, secretion, and neuro-immune responses to sweat in atopic skin, and highlights the value of sweat management., (Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

New Findings: What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass - 0.20 g/kcal -1  = ∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass - 0.20 g kcal -1  = ∆body water. This equation directly controls for the influence of energy expenditure on body mass balance and the approximate offsetting equivalence of respiratory water loss and metabolic water production on body water balance. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100., (Published 2017. This article is a U.S. Government work and is in the public domain in the USA.)

Objective:   To present evidence-based recommendations that promote optimized fluid-maintenance practices for physically active individuals., Background:   Both a lack of adequate fluid replacement (hypohydration) and excessive intake (hyperhydration) can compromise athletic performance and increase health risks. Athletes need access to water to prevent hypohydration during physical activity but must be aware of the risks of overdrinking and hyponatremia. Drinking behavior can be modified by education, accessibility, experience, and palatability. This statement updates practical recommendations regarding fluid-replacement strategies for physically active individuals., Recommendations:   Educate physically active people regarding the benefits of fluid replacement to promote performance and safety and the potential risks of both hypohydration and hyperhydration on health and physical performance. Quantify sweat rates for physically active individuals during exercise in various environments. Work with individuals to develop fluid-replacement practices that promote sufficient but not excessive hydration before, during, and after physical activity.

The measurement of whole body sweat losses (WBSL) is important to the study of body heat balance, body water balance, establishing guidelines for water and electrolyte consumption, and the study of metabolism and health. In principal, WBSL is measured by an acute change in body mass (ΔBM) in response to a thermoregulatory sweating stimulus. In this Cores of Reproducibility in Physiology (CORP) review, we revisit several basic, but rarely discussed, assumptions important to WBSL research, including the common equivalences: mass = weight = water = sweat. Sources of large potential measurement errors are also discussed, as are best practices for avoiding them. The goal of this CORP review is to ultimately improve the accuracy, reproducibility, and application of WBSL research.

Quantitative assessment of small-fiber peripheral neuropathy often involves an evaluation of the interaction between the C-fiber sudomotor nerve and local sweat rate (SR). Typically, some sort of quantitative sudomotor axon reflex test (QSART) is performed to aid in diagnosing small-fiber dysfunction. The currently used QSART demonstrates only moderate test-retest reliability and therefore limits its usefulness in tracking small-fiber dysfunction. A new experimental model to examine small C-fiber function in the skin using intradermal electrical stimulation and simultaneous monitoring of SR is proposed. Using intradermal electrical stimulation (1.5 and 2.5 mA) and varying stimulus frequency from 0.2 to 64 Hz, a quantitative relationship between the area under the SR-time curve and log 10 stimulus frequency is modeled using a four-parameter logistic equation, providing the following parameters: baseline, plateau, EC 50 , and Hill slope. The model has good to excellent repeatability within the same day (ICC = 0.98), on different days at the same skin site (ICC = 0.80), and when comparing two different skin sites (ICC = 0.78) with a small bias estimate and the line of identity always lying within the 95% limits of agreement. Atropine sulfate (0.1 mg/ml) blocked 90 ± 5% of the electrically induced sweating. Overall, the model provides control over sudomotor nerve activity and a quantitative assessment of SR. Finally, the ability to reproduce the quantitative stimulus-response curve on different days allows for a robust assessment of the relationship between the activation of a sympathetic C-fiber and local SR. NEW & NOTEWORTHY A model for quantitative assessment of C-fiber function in human skin using intradermal electrical stimulation and local sweat rate measurements has been developed. This new electrically induced sweating model is nonpainful and allows for a complete stimulus-response curve plotting the area under the local sweat rate-time curve vs. the log 10 stimulus frequency. The model has good reproducibility and should provide a means of assessing the progression of small C-fiber peripheral neuropathy in humans., (Copyright © 2017 the American Physiological Society.)

The aim of the present study was to determine the β-adrenergic contribution to sweating during incremental exercise in habitually trained males. Nine habitually trained and 11 untrained males performed incremental cycling until exhaustion (20 W/min). Bilateral forearm sweat rates (ventilated capsule) were measured at two skin sites that were transdermally administered via iontophoresis with either 1% propranolol (Propranolol, a nonselective β-adrenergic receptor antagonist) or saline (Control). The sweat rate was evaluated as a function of both relative (percentage of maximum workload) and absolute exercise intensities. The sweat rate at the Propranolol site was lower than the control during exercise at 80 (0.57 ± 0.21 and 0.45 ± 0.19 mg·cm -2 ·min -1 for Control and Propranolol, respectively) and 90% (0.74 ± 0.22 and 0.65 ± 0.17 mg·cm -2 ·min -1 , respectively) of maximum workload in trained males (all P < 0.05). By contrast, no between-site differences in sweat rates were observed in untrained counterparts (all P > 0.05). At the same absolute intensity, higher sweat rates on the control site were observed in trained males relative to the untrained during exercise at 160 (0.23 ± 0.20 and 0.04 ± 0.05 mg·cm -2 ·min -1 for trained and untrained, respectively) and 180 W (0.40 ± 0.20 and 0.13 ± 0.13 mg·cm -2 ·min -1 , respectively) (all P < 0.05), whereas this between-group difference was not observed at the Propranolol site (all P > 0.05). We show that the β-adrenergic mechanism does modulate sweating during exercise at a submaximal high relative intensity in habitually trained males. The β-adrenergic mechanism may in part contribute to the greater sweat production in habitually trained males than in untrained counterparts during exercise. NEW & NOTEWORTHY We demonstrated for the first time that the β-adrenergic mechanism does modulate sweating (i.e., β-adrenergic sweating) during exercise using a localized β-adrenoceptor blockade in humans in vivo. β-Adrenergic sweating was evident in habitually trained individuals during exercise at a submaximal high relative intensity (80-90% maximal work). This observation advances our understanding of human thermoregulation during exercise and of the mechanism that underlies sweat gland adaptation to habitual exercise training., (Copyright © 2017 the American Physiological Society.)

Body odors are potent triggers of disgust and regulate social behaviors in many species. The role of olfaction in disgust-associated behaviors has received scant attention in the research literature, in part because olfactory disgust assessments have required laboratory testing with odors. We have devised the "Body Odor Disgust Scale" (BODS) to facilitate research on olfactory disgust. In this study, we evaluated whether individual differences in BODS scores would be associated with the perception of disgust for sweat samples in a laboratory setting. Results show that BODS was a strong predictor of disgust ratings of sweat samples even when controlling for general disgust sensitivity. In contrast, odor intensity ratings were unrelated to BODS scores. Our findings suggest that the BODS scores reflect body odor disgust perception. The BODS scale might facilitate research on olfactory disgust responses and associated behaviors., (© The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The latest development in wearable technologies has attracted much attention. In particular, collection and analysis of body fluids has been a focus. In this paper, we have reported a wearable microfluidic platform made using conventional fabric materials and laser micromachining to measure the flow rate on a patterned fabric surface, referred to as digital droplet flowmetry (DDF). The proposed wearable DDF is capable of collecting and measuring continuous perspiration with high precision (96% on average) in a real-time fashion over a defined area of skin. We have introduced a theoretical model for the proposed wearable interfacial microfluidic platform, under which various design parameters have been investigated and optimized for various conditions. The novel digitalized measurement principle of DDF provides fast responses, digital readouts, system flexibility, and continuous performance of the flow measurement. Moreover, the proposed DDF platform can be conveniently implemented on regular apparel or a wearable device, and has potential to be applied to dynamic removal, collection and monitoring of biofluids for various physiological and clinical processes.

New Findings: What is the central question of this study? Acetylcholine released from cholinergic nerves can activate both muscarinic and nicotinic receptors. Although each receptor can independently induce cutaneous vasodilatation and eccrine sweating, it remains to be elucidated whether the two receptors interact in order to mediate these responses. What is the main finding and its importance? We show that although nicotinic receptor activation does not modulate muscarinic cutaneous vasodilatation, it lowers the muscarinic receptor agonist threshold at which onset for eccrine sweating (augmentation of muscarinic eccrine sweating) occurs in young men in normothermic resting conditions. These results provide new insights into the physiological significance of nicotinic receptors in the regulation of cutaneous perfusion and eccrine sweating. Acetylcholine released from cholinergic nerves can activate both muscarinic and nicotinic receptors; each is known independently to induce cutaneous vasodilatation and eccrine sweating in humans. However, it is not known whether the two receptors interact in order to mediate cutaneous vasodilatation and eccrine sweating. In 10 young men (27 ± 6 years old), cutaneous vascular conductance and sweat rate were evaluated at intradermal microdialysis sites that were continuously perfused with either lactated Ringer's solution (control) or three different concentrations of nicotine (0.1, 1 and 10 mm), a nicotinic receptor agonist. Co-administration of methacholine, a muscarinic receptor agonist, was performed at all skin sites in a dose-proportional fashion (0.0125, 0.25, 5, 100 and 2000 mm, each for 25 min). Administration of nicotine alone caused dose-dependent transient increases in cutaneous vascular conductance and sweat rate (all P ≤ 0.05), which thereafter returned to pre-nicotine levels, except that a portion of transient responses remained with continuous administration of 10 mm nicotine (both P ≤ 0.05). Cutaneous vascular conductance was increased by administration of ≥0.25 mm methacholine at the control site, and this response was likewise observed in the presence of co-administration of all doses of nicotine used (all P ≤ 0.05). Sweat rate at the control site was increased by administration of ≥0.25 mm methacholine, but the lowest dose of methacholine (0.0125 mm) was able to increase sweat rate in the presence of 10 mm nicotine (P ≤ 0.05). We conclude that nicotinic receptor activation lowers the muscarinic receptor agonist threshold for eccrine sweating (augmentation of muscarinic sweating) but does not affect muscarinic cutaneous vasodilatation in young men in normothermic resting conditions., (© 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.)

New Findings: What is the central question of this study? Does attenuated skin blood flow diminish sweating and reduce the critical environmental limit for heat balance, which indicates maximal heat loss potential, during severe heat stress? What is the main finding and its importance? Isosmotic hypovolaemia attenuated skin blood flow by ∼20% but did not result in different sweating rates, mean skin temperatures or critical environmental limits for heat balance compared with control and volume-infusion treatments, suggesting that the lower levels of skin blood flow commonly observed in aged and diseased populations may not diminish maximal whole-body heat dissipation. Attenuated skin blood flow (SkBF) is often assumed to impair core temperature (T c ) regulation. Profound pharmacologically induced reductions in SkBF (∼85%) lead to impaired sweating, but whether the smaller attenuations in SkBF (∼20%) more often associated with ageing and certain diseases lead to decrements in sweating and maximal heat loss potential is unknown. Seven healthy men (28 ± 4 years old) completed a 30 min equilibration period at 41°C and a vapour pressure (P a ) of 2.57 kPa followed by incremental steps in P a of 0.17 kPa every 6 min to 5.95 kPa. Differences in heat loss potential were assessed by identifying the critical vapour pressure (P crit ) at which an upward inflection in T c occurred. The following three separate treatments elicited changes in plasma volume to achieve three distinct levels of SkBF: control (CON); diuretic-induced isosmotic dehydration to lower SkBF (DEH); and continuous saline infusion to maintain SkBF (SAL). The T c , mean skin temperature (T sk ), heart rate, mean laser-Doppler flux (forearm and thigh; LDF mean ), mean local sweat rate (forearm and thigh; LSR mean ) and metabolic rate were measured. In DEH, a 14.2 ± 5.7% lower plasma volume resulted in a ∼20% lower LDF mean in perfusion units (PU) (DEH, 139 ± 23 PU; CON, 176 ± 22 PU; and SAL, 186 ± 22 PU; P = 0.034). However, LSR mean and whole-body sweat losses were unaffected by treatment throughout (P > 0.482). The P crit for T c was similar between treatments (CON, 5.05 ± 0.30 kPa; DEH, 4.93 ± 0.16 kPa; and SAL, 5.12 ± 0.10 kPa; P = 0.166). Furthermore, no differences were observed in the skin-air temperature gradient, metabolic rate or changes in T c (P > 0.197). In conclusion, a ∼20% reduction in SkBF alters neither sweat rate nor the upper limit for heat loss from the skin during non-encapsulated passive heat stress., (© 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.)

Background . Sweat is an aggravating factor in atopic dermatitis (AD), regardless of age. Sweat allergy may be involved in AD aggravated by sweating. Objective. We investigated whether sweat exacerbates adult AD symptoms and examined the extent of sweat allergy's involvement. Method. We asked 34 AD patients (17 men, 17 women; mean age: 27.8 years) to record the extent to which sweat aggravated their symptoms on a 10-point numerical scale. Participant responses were compared with histamine release tests (HRT). Furthermore, 24 of the patients received instructions on methods of sweat management, and their outcomes were evaluated on a 10-point scale. Results. Sweat HRT results were class ≥ 2 in 13 patients, but HRT results were not correlated with the patients' self-assessments of symptom aggravation by sweat. One month after receiving sweat management instructions, a low mean score of 4.6 was obtained regarding whether active sweating was good, but a high mean score of 7.0 was obtained in response to whether the sweat management instructions had been helpful. Conclusion . Our investigation showed that patients' negative impressions of sweat might derive from crude personal experiences that are typically linked to sweating. Sweat management for patients with adult atopic dermatitis was extremely useful regardless of sweat allergy., Competing Interests: The authors declare no conflict of interests.

Personal cooling garments (PCGs) have gained increased attention in recent years due to heat stress and strain in the working environment. The present study was conducted in hot environments of an iron foundry to evaluate the efficacy of a battery-operated PCG. Twenty-four workers were exposed to climatic conditions of 35.89 ± 1.25 °C, 35% relative humidity during 90-min work with PCG and habitual clothing (HC). Mean weighted skin temperature was significantly lower by 4.84 ± 1.05 °C compared with HC 0.38 ± 1.02 °C (p < 0.05). A statistically significant difference was also observed for 0.492 ± 0.26 g mean sweat loss in the PCG group compared with 0.775 ± 0.42 g in the HC group (p < 0.05). Heart rate, and back and chest skin temperatures were comparatively more reduced in the PCG group compared with the HC group. PCG provides a practical and economical way of alleviating the physiological effects of heat stress when environmental control is not feasible.

Objective: Neurofibromatosis type 1 (NF1) causes neural and cutaneous disorders and reduced exercise capacity. Exercise/heat exposure increasing internal temperature must be compensated by eccrine sweat function and warmed skin vasodilation. We suspected NF1 could adversely affect eccrine sweat function and/or vascular thermoregulatory responses (VTR)., Methods: The eccrine sweat function and VTR of 25 NF1 volunteers (14 males, 11 females; 16-57 years old) were compared with 23 non-NF1 controls matched by sex, age, height and weight (CG). Sweating was induced by 1) pilocarpine 1% iontophoresis (PILO); and 2) by passive heating (HEAT) via the lower third of the legs being immersed in 42°C water for one hour. Previously established eccrine sweat function and VTR protocols were used., Results: The NF1 group showed: a) lower sweat rate than the CG group during PILO; b) a smaller diastolic pressure decrease; and c) higher tympanic temperatures than controls during HEAT (p < 0.05)., Conclusion: Reduced sweating and vascular thermoregulatory responses suggest autonomic dysfunction in NF1 individuals.

Background: CFTR dysfunction can be involved in CBAVD, pancreatitis or bronchiectasis., Methods: Subjects with cystic fibrosis-like disease, equivocal sweat chloride concentrations and no or one disease-causing CFTR mutation were investigated by intestinal current and/or nasal potential difference measurements., Results: A subgroup of female patients who had been diagnosed to suffer from non-allergic asthma showed intermediary chloride concentrations in sweat test, normal chloride secretory responses in the intestine and an abnormal nasal potential difference with Sermet scores in the cystic fibrosis range., Conclusion: Non-allergic asthma is a clinical entity that may be associated with CFTR dysfunction of the respiratory epithelium., (Copyright © 2015 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Biofeedback training is a technique through which one can learn to control usually uncontrollable inner body functions, such as brain waves, heart rate or electrodermal activity (EDA). These 'hidden' biological signals are measured from a participant and fed back during the training, e.g., through visual and auditory changes on a computer screen. With practice, the participant learns to control this feedback, and ultimately to control their bodily responses without needing the feedback. In this article, the application of EDA biofeedback will be introduced as a therapy for specific neurological conditions.

The objective of the present experimental molecular-genetic study of DNA contained in of human fingerprints was to establish the relationship between the reference genetic profiles and the genotypes of the individuals leaving their fingerprints on a smooth metal object. The biological material for the purpose of the investigation was sampled at different time intervals. The were taken using a scotch tape and used to obtain the complete genetic profile immediately after the fingerprints had been left as well as within the next 24 hours and one week. It proved impossible to identify the complete genetic profile one month after the fingerprints had been left. The alleles not typical for reference samples were identified within one week after swabbing the material from the metal surface. The results of the sudy can be explained by the decrease of the concentration of the initial DNA-matrix in the samples due to its degradation in the course of time. It is concluded that the parallel genetic analysis is needed if reliable evidence of identity of the profiles of interest or its absence is to be obtained.

Although recent research on the pathogenesis of allergic skin diseases such as atopic dermatitis has focused on defects in skin genes important for maintaining skin barrier function, the fact that excreted sweat has an overwhelmingly great capacity to increase skin surface hydration and contains moisturizing factors has long been ignored: the increase in water loss induced by these gene defects could theoretically be compensated fully by a significant increase in sweating. In this review, the dogma postulating the detrimental role of sweat in these diseases has been challenged on the basis of recent findings on the physiological functions of sweat, newly recognized sweat gland-/duct-related skin diseases, and therapeutic approaches to the management of these diseases. We are now beginning to appreciate that sweat glands/ducts are a sophisticated regulatory system. Furthermore, depending on their anatomical location and the degree of the impairment, this system might have a different function: sweating responses in sweat glands/ducts located at the folds in hairy skin such as on the trunk and extremities could function as natural regulators that maintain skin hydration under quiescent basal conditions, in addition to the better-studied thermoregulatory functions, which can be mainly mediated by those at the ridges. The normal functioning of sweat could be disturbed in various inflammatory skin diseases. Thus, we should recognize sweating disturbance as an etiologic factor in the development of these diseases., (© 2016 S. Karger AG, Basel.)

Individuals with systemic arterial hypertension have a higher risk of heat-related complications. Thus, the aim of this study was to examine the thermoregulatory responses of hypertensive subjects during recovery from moderate-intensity exercise performed in the heat. A total of eight essential hypertensive (H) and eight normotensive (N) male subjects (age=46.5±1.3 and 45.6±1.4 years, body mass index=25.8±0.8 and 25.6±0.6 kg/m2, mean arterial pressure=98.0±2.8 and 86.0±2.3 mmHg, respectively) rested for 30 min, performed 1 h of treadmill exercise at 50% of maximal oxygen consumption, and rested for 1 h after exercise in an environmental chamber at 38°C and 60% relative humidity. Skin and core temperatures were measured to calculate heat exchange parameters. Mean arterial pressure was higher in the hypertensive than in the normotensive subjects throughout the experiment (P<0.05, unpaired t-test). The hypertensive subjects stored less heat (H=-24.23±3.99 W·m-2vs N=-13.63±2.24 W·m-2, P=0.03, unpaired t-test), experienced greater variations in body temperature (H=-0.62±0.05°C vsN=-0.35±0.12°C, P=0.03, unpaired t-test), and had more evaporated sweat (H=-106.1±4.59 W·m-2vs N=-91.15±3.24 W·m-2, P=0.01, unpaired t-test) than the normotensive subjects during the period of recovery from exercise. In conclusion, essential hypertensive subjects showed greater sweat evaporation and increased heat dissipation and body cooling relative to normotensive subjects during recovery from moderate-intensity exercise performed in hot conditions.

The water absorption and transport properties of fabrics are critical to wear comfort, especially for sportswear and protective clothing. A new testing apparatus, namely Forced Flow Water Transport Tester (FFWTT), was developed for characterizing the transplanar and in-plane wicking properties of fabrics based on gravimetric and image analysis technique. The uniqueness of this instrument is that the rate of water supply is adjustable to simulate varying sweat rates with reference to the specific end-use conditions ranging from sitting, walking, running to other strenuous activities. This instrument is versatile in terms of the types of fabrics that can be tested. Twenty four types of fabrics with varying constructions and surface finishes were tested. The results showed that FFWTT was highly sensitive and reproducible in differentiating these fabrics and it suggests that water absorption and transport properties of fabrics are sweat rate-dependent. Additionally, two graphic methods were proposed to map the direction of liquid transport and its relation to skin wetness, which provides easy and direct comparison among different fabrics. Correlation analysis showed that FFWTT results have strong correlation with subjective wetness sensation, implying validity and usefulness of the instrument.