Skin blood flow in adult human thermoregulation: how it works, when it does not, and why

Association between short-term ozone exposure and allergic conjunctivitis in China: A multi-city case-crossover study

Short-term exposure to ozone has been linked to multiple allergic diseases, but the relationship between ozone exposure and allergic conjunctivitis (AC) remains unclear. This study aimed to investigate the association between short-term exposure to ozone and the risk of AC. We conducted a time-stratified case-crossover study across five Chinese cities from 2014 to 2022. Daily outpatient visit records for AC were identified in five hospitals using either the diagnosis name or ICD-10 code H10.1. Data on air pollution and meteorological conditions were also collected. We first examined the city-specific association between short-term ozone exposure and AC using conditional logistic regression. A random-effects meta-analysis was then conducted to obtain overall estimates. During the study period, 130,093 outpatient visits for AC occurred, with 58.8% (76,482) being male and 41.2% (53,611) female. A one-standard-deviation (SD) increase in ozone was associated with an 8.3% increase (95% CI: 3.8%, 13.0%) in AC outpatient visits. Similar positive associations were observed when adjusting for other pollutants (PM2.5, CO, SO2 and NO2) in two-pollutant and multi-pollutant models. Furthermore, the positive association remained consistent when using mixed-effects regression models or further adjusting for meteorological conditions. In addition, no effect modification of the AC-ozone association by sex, age and season was apparent. This study provides evidence supporting a positive association between short-term ozone exposure and AC risk in China. This highlights the potential value of mitigating ozone pollution to reduce the risk of ocular surface disorders.

Pre-exercise cryotherapy reduces myoglobin and creatine kinase levels after eccentric muscle stress in young women

Introduction: The aim of this study was to investigate the effect of pre-exercise whole-body cryotherapy (WBC) on muscle damage indicators following eccentric treadmill exercise in young women. Methods: Twenty-seven participants underwent two 1-h downhill treadmill runs, replicating 60% of their maximal oxygen uptake, with a 4-week intermission for recovery and treatment application. In this intermission, one group underwent 20 sessions of WBC, delivered five times a week at -120°C for 3 min each, while the comparison group received no such treatment. Markers of muscle injury-serum myoglobin concentration, creatine kinase and lactate dehydrogenase activity and also uric acid, and cell-free DNA concentration-were measured before and after downhill runs. Results: The study observed a notable reduction in post-exercise myoglobin and CK levels in the WBC group after the second running session. Discussion: The results suggest that WBC can have a protective effects against muscle damage resulting from eccentric exercise.

Genomic regions, candidate genes, and pleiotropic variants associated with physiological and anatomical indicators of heat stress response in lactating sows

BACKGROUND

Heat stress (HS) poses significant threats to the sustainability of livestock production. Genetically improving heat tolerance could enhance animal welfare and minimize production losses during HS events. Measuring phenotypic indicators of HS response and understanding their genetic background are crucial steps to optimize breeding schemes for improved climatic resilience. The identification of genomic regions and candidate genes influencing the traits of interest, including variants with pleiotropic effects, enables the refinement of genotyping panels used to perform genomic prediction of breeding values and contributes to unraveling the biological mechanisms influencing heat stress response. Therefore, the main objectives of this study were to identify genomic regions, candidate genes, and potential pleiotropic variants significantly associated with indicators of HS response in lactating sows using imputed whole-genome sequence (WGS) data. Phenotypic records for 18 traits and genomic information from 1,645 lactating sows were available for the study. The genotypes from the PorcineSNP50K panel containing 50,703 single nucleotide polymorphisms (SNPs) were imputed to WGS and after quality control, 1,622 animals and 7,065,922 SNPs were included in the analyses.

RESULTS

A total of 1,388 unique SNPs located on sixteen chromosomes were found to be associated with 11 traits. Twenty gene ontology terms and 11 biological pathways were shown to be associated with variability in ear skin temperature, shoulder skin temperature, rump skin temperature, tail skin temperature, respiration rate, panting score, vaginal temperature automatically measured every 10 min, vaginal temperature measured at 0800 h, hair density score, body condition score, and ear area. Seven, five, six, two, seven, 15, and 14 genes with potential pleiotropic effects were identified for indicators of skin temperature, vaginal temperature, animal temperature, respiration rate, thermoregulatory traits, anatomical traits, and all traits, respectively.

CONCLUSIONS

Physiological and anatomical indicators of HS response in lactating sows are heritable but highly polygenic. The candidate genes found are associated with important gene ontology terms and biological pathways related to heat shock protein activities, immune response, and cellular oxidative stress. Many of the candidate genes with pleiotropic effects are involved in catalytic activities to reduce cell damage from oxidative stress and cellular mechanisms related to immune response.

Exercise-induced changes in lower limbs skin temperature against plasma ATP among individuals with various type and level of physical activity

The objective of the study was to examine the lower limbs skin temperature (TSK) changes in response to exhaustive whole-body exercise in trained individuals in reference to changes in plasma adenosine triphosphate (ATP). Eighteen trained participants from distinct sport type ‒ endurance (25.2 ± 4.9 yr) and speed-power (25.8 ± 3.1 yr), and 9 controls (24,9 ± 4,3 yr) ‒ were examined. Lower limbs TSK and plasma ATP measures were applied in parallel in response to incremental treadmill test and during 30-min recovery period. Plasma ATP kinetics were inversely associated to changes in TSK. The first significant decrease in TSK (76-89% of V˙ O2MAX) occurred shortly before a significant plasma ATP increase (86-97% of V˙ O2MAX). During recovery, TSK increased, reaching pre-exercise values (before exercise vs. after 30-min recovery: 31.6 ± 0.4 °C vs. 32.0 ± 0.8 °C, p = 0.855 in endurance; 32.4 ± 0.5 °C vs. 32.9 ± 0.5 °C, p = 0.061 in speed-power; 31.9 ± 0.7 °C vs. 32.4 ± 0.8 °C, p = 0.222 in controls). Plasma ATP concentration did not returned to pre-exercise values in well trained participants (before exercise vs. after 30-min recovery: 699 ± 57 nmol l-1 vs. 854 ± 31 nmol l-1, p < 0.001, η2 = 0.961 and 812 ± 35 nmol l-1 vs. 975 ± 55 nmol l-1, p < 0.001, η2 = 0.974 in endurance and speed-power, respectively), unlike in controls (651 ± 40 nmol l-1 vs. 687 ± 61 nmol·l-1, p = 0.58, η2 = 0.918). The magnitude of TSK and plasma ATP response differed between the groups (p < 0.001, η2 = 0.410 for TSK; p < 0.001, η2 = 0.833 for plasma ATP). We conclude that lower limbs TSK change indirectly corresponds to the reverse course of plasma ATP during incremental exercise and the magnitude of the response depends on the level of physical activity and the associated to it long-term metabolic adaptation.

Understanding Why Homeopathic Medicines are Used for Menopause: Searching for Insights into Neuroendocrine Features

BACKGROUND

 Menopause is a physiological event that marks the end of a woman's reproductive stage in life. Vasomotor symptoms and changes in mood are among its most important effects. Homeopathy has been used for many years in treating menopausal complaints, though clinical and pre-clinical research in this field is limited. Homeopathy often bases its prescription on neuropsychiatric symptoms, but it is unknown if homeopathic medicines (HMs) exert a neuroendocrine effect that causes an improvement in vasomotor symptoms and mood during menopause.

OBJECTIVES

 The study's objectives were to address the pathophysiological changes of menopause that could help in the understanding of the possible effect of HMs at a neuroendocrine level, to review the current evidence for two of the most frequently prescribed HMs for menopause (Lachesis mutus and Sepia officinalis), and to discuss the future directions of research in this field.

METHODS

 An extensive literature search for the pathophysiologic events of menopause and depression, as well as for the current evidence for HMs in menopause and depression, was performed.

RESULTS

 Neuroendocrine changes are involved in the pathophysiology of vasomotor symptoms and changes in mood during menopause. Gonadal hormones modulate neurotransmitter systems. Both play a role in mood disorders and temperature regulation. It has been demonstrated that Gelsemium sempervirens, Ignatia amara and Chamomilla matricaria exert anxiolytic effects in rodent models. Lachesis mutus and Sepia officinalis are frequently prescribed for important neuropsychiatric and vasomotor symptoms. Dopamine, a neurotransmitter involved in mood, is among the constituents of the ink of the common cuttlefish, Sepia officinalis.

CONCLUSION

 Based on all the pathophysiologic events of menopause and the improvement in menopausal complaints that certain HMs show in daily practice, these medicines might have a direct or indirect neuroendocrine effect in the body, possibly triggered via an as-yet unidentified biological mechanism. Many unanswered questions in this field require further pre-clinical and clinical research.

Arterio-venous Anastomoses of the Sucquet-Hoyer Type: Complexity and Distribution in the Human Dermis

Our study aims at providing detailed information on numbers, form, and spatial distribution of arterio-venous anastomoses of the Sucquet-Hoyer type in the dermis of the nail bed, nail fold corner, thumb pad, arm, nose, glabella, lip, and ear. It further aims at providing a system, which relies on objective morphologic criteria for classifying Sucquet-Hoyer canals (SHCs). Using high-resolution episcopic microscopy (HREM), digital volume data of eight samples of each skin region were produced. Virtual three-dimensional (3D) models of the dermally located SHCs were created, and their 3D tortuosity (τ) values were determined. Dermal SHCs were identified in all 24 finger samples and in 1 lip sample. Beneath a field of 2 × 2 mm2, an average of four were located in the nail bed, three in the dermis of the thumb pad, and one in the dermis of the nail fold corner. Only a single dermal SHC was found in one lip sample. No SHCs were observed in the dermis of the other samples. The τ values of the SHCs ranged from 1.11 to 10. Building on these values, a classification system was designed, which distinguishes four SHC classes. The dermal distribution of the SHCs of different classes was similar in all specimens.

Heat and Cardiovascular Mortality: An Epidemiological Perspective

As global temperatures rise, extreme heat events are projected to become more frequent and intense. Extreme heat causes a wide range of health effects, including an overall increase in morbidity and mortality. It is important to note that while there is sufficient epidemiological evidence for heat-related increases in all-cause mortality, evidence on the association between heat and cause-specific deaths such as cardiovascular disease (CVD) mortality (and its more specific causes) is limited, with inconsistent findings. Existing systematic reviews and meta-analyses of epidemiological studies on heat and CVD mortality have summarized the available evidence. However, the target audience of such reviews is mainly limited to the specific field of environmental epidemiology. This overarching perspective aims to provide health professionals with a comprehensive overview of recent epidemiological evidence of how extreme heat is associated with CVD mortality. The rationale behind this broad perspective is that a better understanding of the effect of extreme heat on CVD mortality will help CVD health professionals optimize their plans to adapt to the changes brought about by climate change and heat events. To policymakers, this perspective would help formulate targeted mitigation, strengthen early warning systems, and develop better adaptation strategies. Despite the heterogeneity in evidence worldwide, due in part to different climatic conditions and population dynamics, there is a clear link between heat and CVD mortality. The risk has often been found to be higher in vulnerable subgroups, including older people, people with preexisting conditions, and the socioeconomically deprived. This perspective also highlights the lack of evidence from low- and middle-income countries and focuses on cause-specific CVD deaths. In addition, the perspective highlights the temporal changes in heat-related CVD deaths as well as the interactive effect of heat with other environmental factors and the potential biological pathways. Importantly, these various aspects of epidemiological studies have never been fully investigated and, therefore, the true extent of the impact of heat on CVD deaths remains largely unknown. Furthermore, this perspective also highlights the research gaps in epidemiological studies and the potential solutions to generate more robust evidence on the future consequences of heat on CVD deaths.

Impact of regular cold exposure on electrical skin resistance in patients with joint degenerative diseases

OBJECTIVE

Common features in chronic inflammatory disease patients (CIDP) are inflammation, mental stress (MS), and autonomic nervous system imbalance. Whole-body cryotherapy (WBC) exposure and regular physical exercise are known to regulate these features. In this study, we assessed the impact of regular physical exercise and the use of WBC exposure in CIDP on the level of electrical skin resistance (SR) to evaluate the skin sympathetic nervous activity and and estimate MS levels.

METHODS

SR was evaluated before and after a 10-day-period of daily physical exercise preceded or not by WBC (3 min at -110°C) in two groups of 134 CIDP (WBC vs. non-WBC groups).

RESULTS

At baseline, the number of severe MS patients was similar in both groups. However, after the training period, the number of severe MS patients significantly decreased in the WBC group, only. An increase in SR (a decrease in stress level) was noted in the WBC group only, and such increase was higher in men than in women and in patients younger than 60 versus patients older than 60 years old.

CONCLUSION

The use of daily WBC combined with physical exercise induced physiological adaptations and lowered the sympathetic nervous activity that may reflect a reduced level of MS in CIDP. These adaptations seem to depend on gender and age.

Effects of Temperature, Duration, and Heating Height of Foot Thermal Therapy on Sleep Quality of Older Adults: A Systematic Review and Meta-Analysis

Background: Sleep disturbances, which are common problems in older adults, often lead to cognitive decline and depression and may even increase mortality risk. Foot thermal therapy is a simple and safe approach for improving sleep and is associated with relatively few side effects. However, the effect of different operations of foot thermal therapy on sleep quality in older adults is inconclusive. This study aimed to access the effects of temperature, duration, and heating height of foot thermal therapy (administered through a footbath) on the subjective and objective sleep quality of older adults. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline, eight databases were searched for all relevant articles published up to July 2023, and a rigorous systematic review and meta-analysis was conducted. This study was registered in the PROSPERO database (CRD42022383460). Inclusion criteria were: (1) participants with a mean age ≥60 years; (2) interventions that included foot thermal therapy; (3) a control group that received routine care but no thermal therapy; (4) outcome measurements that assessed sleep quality; and (5) the studies that utilized randomized controlled trials or quasi-experimental studies. Methodological quality was assessed using the Joanna Briggs Institute critical appraisal tools. The meta-analysis was performed using RevMan version 5.4. Results: A total of 11 studies were included. Foot thermal therapy before bedtime improved subjective sleep quality in older adults, with optimal parameters of 40°C temperature (standardized mean difference [SMD] = 0.66, 95% confidence interval [CI]: 0.33 to 0.99), ≤20-min duration (SMD = 0.66, 95% CI: 0.39 to 0.93), and 10 cm heating height (SMD = 0.78, 95% CI: 0.45 to 1.11). Subgroup analyses revealed that a temperature of 41°C-42°C can improve objective sleep latency (SMD = 0.54, 95% CI: 0.09 to 0.99). Conclusions: It is recommended to administer foot thermal therapy (40°C; ≤20 min; 10 cm above the ankle) to older adults 1 h before their bedtime. If they have trouble falling asleep, the temperature can be increased to 41°C-42°C.

Vascular read-out for TRP channel functionality on distal peripheral nerve endings in healthy men

BACKGROUND

Quantification of the vasodilation after topical application of capsaicin or cinnamaldehyde is often implemented to indirectly assess Transient Receptor Potential (TRP) Vanilloid 1 (TRPV1) or Ankyrin 1 (TRPA1) functionality respectively. This method has been well-established on the human forearm. However, to enable TRP functionality assessments in distal peripheral neuropathy, the vascular response upon TRP activation on dorsal finger skin was characterized.

METHODS

Two doses of cinnamaldehyde (3 % and 10 % v/v) and capsaicin (300 μg and 1000 μg) were topically applied (20 μL) on the skin of the mid three proximal phalanges in 17 healthy men. The dose-response, and inter-hand and inter-period reproducibility of the dermal blood flow (DBF) increase was assessed using Laser Speckle Contrast Imaging (LSCI) during 60 min post-application. Linear mixed models explored dose-driven differences, whereas the intra-class correlation coefficient (ICC) estimated the reproducibility of the vascular response.

RESULTS

Both doses of cinnamaldehyde and capsaicin induced a robust, dose-dependent increase in DBF. The vascular response to cinnamaldehyde 10 % on finger skin, expressed as area under the curve, correlated well over time (ICC = 0.66) and excellently between hands (ICC = 0.87). Similarly, the response to capsaicin 1000 μg correlated moderately over time (ICC = 0.50) and well between hands (ICC = 0.73).

CONCLUSION

The vascular response upon topical cinnamaldehyde and capsaicin application on finger skin is an alternative approach for measurements on forearm skin. Thereby, it is a promising vascular read-out to investigate the pathophysiology, and TRP involvement in particular, of specific peripheral neuropathic pain syndromes.

Interaction between local blood flow and tolerance to prolonged pain in the elderly

PURPOSE

We aimed to explore the link between local vasodilation and pain perception in elderly subjects, testing the hypothesis that altered local cutaneous blood flow participates in the decrease in pain tolerance with age.

METHOD

Sixty-eight young and 83 older participants performed a pain tolerance test in which they hold their hand in an airtight box in which air temperature was regulated at 65 °C until the pain became unbearable. Participants continuously estimated pain intensity. Skin temperature and local blood flow in the box-exposed hand were continuously monitored.

RESULTS

In the young group, 97% of subjects resisted pain until the end of the test, whereas only 53% in the elderly group managed to do so, indicating that pain tolerance is impaired in the elderly. Among all participants, the skin temperature associated with the first pain sensation was below the threshold for nociceptor activation (43 °C). Interestingly, blood flow in the elderly group was correlated with pain judgment, whereas no such correlation was observed in the young.

CONCLUSION

Our results suggest that the local vasodilator response induced by local heating may be involved in pain perception and may influence thermal pain tolerance with aging. These results could contribute to a better understanding of vascular deficits and the development of chronic pain in vascular pathologies.

The Impact of Climate Change and Extreme Weather Conditions on Cardiovascular Health and Acute Cardiovascular Diseases

Climate change is widely recognized as one of the most significant challenges facing our planet and human civilization. Human activities such as the burning of fossil fuels, deforestation, and industrial processes release greenhouse gases into the atmosphere, leading to a warming of the Earth's climate. The relationship between climate change and cardiovascular (CV) health, mediated by air pollution and increased ambient temperatures, is complex and very heterogeneous. The main mechanisms underlying the pathogenesis of CV disease at extreme temperatures involve several regulatory pathways, including temperature-sympathetic reactivity, the cold-activated renin-angiotensin system, dehydration, extreme temperature-induced electrolyte imbalances, and heat stroke-induced systemic inflammatory responses. The interplay of these mechanisms may vary based on individual factors, environmental conditions, and an overall health background. The net outcome is a significant increase in CV mortality and a higher incidence of hypertension, type II diabetes mellitus, acute myocardial infarction (AMI), heart failure, and cardiac arrhythmias. Patients with pre-existing CV disorders may be more vulnerable to the effects of global warming and extreme temperatures. There is an urgent need for a comprehensive intervention that spans from the individual level to a systemic or global approach to effectively address this existential problem. Future programs aimed at reducing CV and environmental burdens should require cross-disciplinary collaboration involving physicians, researchers, public health workers, political scientists, legislators, and national leaders to mitigate the effects of climate change.

Influence of topical menthol gel on thermoregulation and perception while walking in the heat

PURPOSE

Menthol is known to elicit opposing thermoregulatory and perceptual alterations during intense exercise. The current purpose was to determine the thermoregulatory and perceptual effects of topical menthol application prior to walking in the heat.

METHODS

Twelve participants walked (1.6 m s-1, 5% grade) for 30 min in the heat (38 °C, 60% relative humidity) with either a 4% menthol or control gel on the upper (shoulder to wrist) and lower (mid-thigh to ankle) limbs. Skin blood flow (SkBF), sweat (rate, composition), skin conductivity, heart rate, temperature (skin, core), and thermal perception were measured prior to and during exercise.

RESULTS

Skin conductivity expressed as time to 10, 20, 30, and 40 µS was delayed due to menthol (559 ± 251, 770 ± 292, 1109 ± 301, 1299 ± 335 s, respectively) compared to the control (515 ± 260, 735 ± 256, 935 ± 300, 1148 ± 298 s, respectively, p = 0.048). Sweat rate relative to body surface area was lower due to menthol (0.55 ± 0.16 L h-1 m(2)-1) than the control (0.64 ± 0.16 L h-1 m(2)-1, p = 0.049). Core temperature did not differ at baseline between the menthol (37.4 ± 0.3 °C) and control (37.3 ± 0.4 °C, p = 0.298) but was higher at 10, 20, and 30 min due to menthol (37.5 ± 0.3, 37.7 ± 0.2, 38.1 ± 0.3 °C, respectively) compared to the control (37.3 ± 0.4, 37.4 ± 0.3, 37.7 ± 0.3 °C, respectively, p < 0.05). The largest rise in core temperature from baseline was at 30 min during menthol (0.7 ± 0.3 °C) compared to the control (0.4 ± 0.2 °C, p = 0.004). Overall, the menthol treatment was perceived cooler, reaching "slightly warm" whereas the control treatment reached "warm" (p < 0.001).

CONCLUSION

Menthol application to the limbs impairs whole-body thermoregulation while walking in the heat despite perceiving the environment as cooler.

Candidate biomarkers in brown adipose tissue for post-mortem diagnosis of fatal hypothermia

Post-mortem diagnosis of fatal hypothermia (FHT) is challenging in forensic practice because traditional morphological and biochemical methods lack specificity. Recent studies have reported that brown adipose tissue (BAT) is activated during cold-induced non-shivering thermogenesis in mammals, but BAT has not been used to diagnose FHT. The aim of this study was to identify novel biomarkers in BAT for FHT based on morphological changes and differential protein expression. Two FHT animal models were created by exposing mice to 4 or -20 °C at 50% humidity. Morphologically, the unilocular lipid droplet content was significantly increased in BAT of FHT model mice compared with that of control mice. Proteomics analysis revealed a total of 283 and 266 differentially expressed proteins (DEPs) between the 4 or -20 °C FHT subgroups and control group, respectively. In addition, 140 proteins were shared between the FHT subgroups. GO and KEGG analyses revealed that the shared DEPs were mainly enriched in pathways associated with metabolism, oxidative phosphorylation, and thermogenesis. Further screening (|log2FC| > 1.6, q-value (FDR) < 0.05) identified GMFB, KDM1A, DDX6, RAB1B, SHMT-1, CLPTM1, and LMF1 as candidate biomarkers of FHT. Subsequent validation experiments were performed in FHT model mice using classic immunohistochemistry and western blotting. RAB1B and GMFB expression was further verified in BAT specimens from human cases of FHT. The results demonstrate that BAT can be used as a target organ for FHT diagnosis employing RAB1B and GMFB as biological markers, thus providing a new strategy for the post-mortem diagnosis of FHT in forensic practice.

A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise

In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.

A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 2: physiological measurements

In this, the second of four historical reviews on human thermoregulation during exercise, we examine the research techniques developed by our forebears. We emphasise calorimetry and thermometry, and measurements of vasomotor and sudomotor function. Since its first human use (1899), direct calorimetry has provided the foundation for modern respirometric methods for quantifying metabolic rate, and remains the most precise index of whole-body heat exchange and storage. Its alternative, biophysical modelling, relies upon many, often dubious assumptions. Thermometry, used for >300 y to assess deep-body temperatures, provides only an instantaneous snapshot of the thermal status of tissues in contact with any thermometer. Seemingly unbeknownst to some, thermal time delays at some surrogate sites preclude valid measurements during non-steady state conditions. To assess cutaneous blood flow, immersion plethysmography was introduced (1875), followed by strain-gauge plethysmography (1949) and then laser-Doppler velocimetry (1964). Those techniques allow only local flow measurements, which may not reflect whole-body blood flows. Sudomotor function has been estimated from body-mass losses since the 1600s, but using mass losses to assess evaporation rates requires precise measures of non-evaporated sweat, which are rarely obtained. Hygrometric methods provide data for local sweat rates, but not local evaporation rates, and most local sweat rates cannot be extrapolated to reflect whole-body sweating. The objective of these methodological overviews and critiques is to provide a deeper understanding of how modern measurement techniques were developed, their underlying assumptions, and the strengths and weaknesses of the measurements used for humans exercising and working in thermally challenging conditions.

Facial functional networks during resting state revealed by thermal infrared imaging

In recent decades, an increasing number of studies on psychophysiology and, in general, on clinical medicine has employed the technique of facial thermal infrared imaging (IRI), which allows to obtain information about the emotional and physical states of the subjects in a completely non-invasive and contactless fashion. Several regions of interest (ROIs) have been reported in literature as salient areas for the psychophysiological characterization of a subject (i.e. nose tip and glabella ROIs). There is however a lack of studies focusing on the functional correlation among these ROIs and about the physiological basis of the relation existing between thermal IRI and vital signals, such as the electrodermal activity, i.e. the galvanic skin response (GSR). The present study offers a new methodology able to assess the functional connection between salient seed ROIs of thermal IRI and all the pixel of the face. The same approach was also applied considering as seed signal the GSR and its phasic and tonic components. Seed correlation analysis on 63 healthy volunteers demonstrated the presence of a common pathway regulating the facial thermal functionality and the electrodermal activity. The procedure was also tested on a pathological case study, finding a completely different pattern compared to the healthy cases. The method represents a promising tool in neurology, physiology and applied neurosciences.

The Efficacy and Safety of Botulinum Toxin A for the Treatment of Rosacea: A Systematic Review

The off-label use of botulinum toxin type-A (BoNT-A) in treating rosacea seems encouraging, but the evidence is still lacking regarding its efficacy and safety. This study was conducted to summarize the evidence regarding the efficacy and safety of BoNT-A in the treatment of rosacea patients. A comprehensive literature search was conducted in several databases, and 17 studies were included. Before-after and split-face comparisons showed that BoNT-A significantly alleviated the symptoms of facial erythema and flushing and improved the patient's quality of life/satisfaction. However, the symptoms recurred three to six months post-injection, requiring repeated treatments in some patients. The pooled rates of post-injection localized erythema, ecchymosis, and facial muscle affection represented 24.6%, 5.1%, and 4.3%, respectively. BoNT-A seems to be effective in alleviating the symptoms of rosacea with a low rate of adverse events. However, the recurrence of the symptoms a few months after the injection requires repeated sessions, which may raise cost-effectiveness issues. Large-scale clinical trials are required to confirm the effectiveness and define the optimal dosing regimen and the rate of recurrence. Future studies should allow for an adequate follow-up after the treatment, with repeated measurements of the outcomes.

Sensitivity and Specificity of Pulse Oximetry for Identification of Peripheral Artery Disease: A Systematic Review

BACKGROUND

Lower limb peripheral artery disease (PAD) is associated with poor outcomes including ulceration, gangrene, amputations, and mortality. Clinicians therefore routinely perform point-of-care tests in high-risk populations to identify PAD and subsequently implement cardiovascular management and appropriate interventions. Pulse oximetry has been suggested as a useful adjunct test for identifying PAD.

OBJECTIVE

The aim of this systematic review was to determine the sensitivity and specificity of pulse oximetry in the lower limb for identifying PAD.

METHODS

MEDLINE, EMBASE, and CINAHL were searched up until January 10, 2023, to identify studies of sensitivity and specificity of pulse oximetry that used criterion standard diagnostic imaging as a reference standard. Two authors screened articles for inclusion and appraised quality of included studies using the Quality Appraisal for Diagnostic Accuracy Studies, version 2.

RESULTS

A total of 6371 records were screened, and 4 were included. The included studies had a total of 471 participants, with an age range of 41 to 80.6 years. All studies were cross-sectional and conducted in hospital settings. Sensitivity values for pulse oximetry compared with diagnostic imaging in identifying PAD ranged from 44% to 76%, and specificity values ranged from 85% to 96%. There was no consensus regarding measurement techniques and diagnostic thresholds for pulse oximetry, which precluded meta-analysis.

CONCLUSIONS

There is currently inadequate evidence to support the use of pulse oximetry for identifying PAD. Current evidence suggests that pulse oximetry has low levels of sensitivity and is therefore likely to miss PAD when it is present.

The Clinical Validation of Modulated Electro-Hyperthermia (mEHT)

The mEHT method uses tissues' thermal and bioelectromagnetic heterogeneity for the selective mechanisms. The success of the therapy for advanced, relapsed, and metastatic aggressive tumors can only be demonstrated by measuring survival time and quality of life (QoL). The complication is that mEHT-treated patients cannot be curatively treated any longer with "gold standards", where the permanent progression of the disease, the refractory, relapsing situation, the organ failure, the worsening of blood counts, etc., block them. Collecting a cohort of these patients is frequently impossible. Only an intent-to-treat (ITT) patient group was available. Due to the above limitations, many studies have single-arm data collection. The Phase III trial of advanced cervix tumors subgrouping of HIV-negative and -positive patients showed the stable efficacy of mEHT in all patients' subgroups. The single-arm represents lower-level evidence, which can be improved by comparing the survival data of various studies from different institutes. The Kaplan-Meier probability comparison had no significant differences, so pooled data were compared to other methods. Following this approach, we demonstrate the feasibility and superiority of mEHT in the cases of glioblastoma multiform, pancreas carcinomas, lung tumors, and colorectal tumors.

Partial-body cryostimulation does not impact peripheral microvascular responsiveness but reduces muscular metabolic O2 consumption (mV˙O2) at rest

This study aimed to investigate the effect of partial-body cryostimulation (PBC) on microvascular responsiveness and muscular metabolic O2 consumption rate (mV˙O2). Twenty healthy young adults (ten males and ten females) underwent a post-occlusive reactive hyperemia (PORH) test at the flexor digitorum superficialis area before and after a 3-min PBC session and a 3-min control session. Using near-infrared spectroscopy, occlusion and reperfusion slopes were calculated: oxyhemoglobin ([HbO2]) decrease rate ([HbO2] slope 1), deoxyhaemoglobin ([HHb]) increase rate ([HHb] slope 1), [HbO2] increase rate ([HbO2] slope 2), and [HHb] increase rate ([HHb] slope 2. Using HbO2 kinetics during the occlusion, mV˙O2 was also calculated to characterize myocytes' metabolic O2 consumption. HbO2 slope 1 value was lower after PBC than before PBC (-0.15 ± 0.08 vs -0.24 ± 0.11 s-1; respectively; P < 0.05) in male participants only. A lower [HHb] slope 1 was also observed after PBC compared to before PBC (0.18 ± 0.10 vs 0.24 ± 0.16 s-1; P < 0.05) with no interaction for sex categories. mV˙O2 was significantly lower after PBC than before (pre values 14.75 ± 3.94 vs 18.47 ± 5.73 μMO2Hb.s-1; respectively; P < 0.01) with no interaction between sex categories. No changes in the calculated slope 2 were observed. These findings suggest that a single session of PBC reduces the muscular metabolic O2 needs at rest; however, it does not alter the vascular ability to provide O2 to the myocytes.

Assessment of short-term heat effects on cardiovascular mortality and vulnerability factors using small area data in Europe

BACKGROUND

Short-term associations between heat and cardiovascular disease (CVD) mortality have been examined mostly in large cities. However, different vulnerability and exposure levels may contribute to spatial heterogeneity. This study assessed heat effects on CVD mortality and potential vulnerability factors using data from three European countries, including urban and rural settings.

METHODS

We collected daily counts of CVD deaths aggregated at the small-area level in Norway (small-area level: municipality), England and Wales (lower super output areas), and Germany (district) during the warm season (May-September) from 1996 to 2018. Daily mean air temperatures estimated by spatial-temporal models were assigned to each small area. Within each country, we applied area-specific Quasi-Poisson regression using distributed lag nonlinear models to examine the heat effects at lag 0-1 days. The area-specific estimates were pooled by random-effects meta-analysis to derive country-specific and overall heat effects. We examined individual- and area-level heat vulnerability factors by subgroup analyses and meta-regression, respectively.

RESULTS

We included 2.84 million CVD deaths in analyses. For an increase in temperature from the 75th to the 99th percentile, the pooled relative risk (RR) for CVD mortality was 1.14 (95% CI: 1.03, 1.26), with the country-specific RRs ranging from 1.04 (1.00, 1.09) in Norway to 1.24 (1.23, 1.26) in Germany. Heat effects were stronger among women [RRs (95% CIs) for women and men: 1.18 (1.08, 1.28) vs. 1.12 (1.00, 1.24)]. Greater heat vulnerability was observed in areas with high population density, high degree of urbanization, low green coverage, and high levels of fine particulate matter.

CONCLUSION

This study provides evidence for the heat effects on CVD mortality in European countries using high-resolution data from both urban and rural areas. Besides, we identified individual- and area-level heat vulnerability factors. Our findings may facilitate the development of heat-health action plans to increase resilience to climate change.

Effectiveness of Cryotherapy on Cancer Therapy-Induced Oral Mucositis: An Umbrella Review

BACKGROUND

Oral mucositis (OM) considerably affects the experience of patients with cancer during treatment. This study investigated the effects of cryotherapy on cancer therapy-induced OM.

OBJECTIVE

This study aimed to systematically appraise evidence on whether cryotherapy can reduce the incidence and severity of OM.

METHODS

We conducted an umbrella review to examine the effect of cryotherapy on cancer-related OM. The primary outcome was the incidence and severity of OM. We performed a subgroup analysis including solid cancers and hematological malignancies.

RESULTS

Five meta-analyses were included. Cryotherapy could more effectively reduce the incidence of severe OM (risk ratio [RR], 0.37; 95% prediction interval [PI], 0.22-0.64). In the subgroup analyses of solid cancers or hematological malignancies, cryotherapy significantly reduced the incidence of grades 2 to 4 OM in patients with solid cancers (RR, 0.51; 95% PI, 0.34-0.78 and RR, 0.52; 95% PI, 0.36-0.74). However, no significant difference was observed in the incidence of OM in patients with hematological malignancies regarding any grade or grade 3 or 4 OM. Moreover, cryotherapy did not significantly reduce the OM duration (mean difference, -0.13; 95% PI, -20.89 to 20.63; mean difference, -2.99, 95% PI, -8.10 to 2.12).

CONCLUSION

Cryotherapy can reduce the incidence of severe OM induced by chemotherapy or radiotherapy.

IMPLICATION FOR PRACTICE

We recommend the inclusion of this safe, simple, and convenient intervention in chemotherapy or radiotherapy plans. Additional clinical trials are warranted to extend the limited evidence on the effectiveness of cryotherapy in reducing the severity and duration of OM.

SubQ-Sim: A Subcutaneous Physiologically Based Biopharmaceutics Model. Part 1: The Injection and System Parameters

PURPOSE

To construct a detailed mechanistic and physiologically based biopharmaceutics model capable of predicting 1) device-formulation-tissue interaction during the injection process and 2) binding, degradation, local distribution, diffusion, and drug absorption, following subcutaneous injection. This paper is part of a series and focusses on the first aspect.

METHODS

A mathematical model, SubQ-Sim, was developed incorporating the details of the various substructures within the subcutaneous environment together with the calculation of dynamic drug disposition towards the lymph ducts and venous capillaries. Literature was searched to derive key model parameters in healthy and diseased subjects. External factors such as body temperature, exercise, body position, food or stress provide a means to calculate the impact of "life events" on the pharmacokinetics of subcutaneously administered drugs.

RESULTS

The model predicts the tissue backpressure time profile during the injection as a function of injection rate, volume injected, solution viscosity, and interstitial fluid viscosity. The shape of the depot and the concentrations of the formulation and proteins in the depot are described. The model enables prediction of formulation backflow following premature needle removal and the resulting formulation losses. Finally, the effect of disease (type 2 diabetes) or the presence of recombinant human hyaluronidase in the formulation on the injection pressure, are explored.

CONCLUSIONS

This novel model can successfully predict tissue back pressure, depot dimensions, drug and protein concentration and formulation losses due to incorrect injection, which are all important starting conditions for predicting drug absorption from a subcutaneous dose. The next article will describe the absorption model and validation against clinical data.

Biomedical aspects of entropy generation on MHD flow of TiO2-Ag/blood hybrid nanofluid in a porous cylinder

This study aims to analyze the heat transfer behavior of the magnetohydrodynamic blood-based Casson hybrid nanofluid in the occurrence of a non-Fourier heat flux model and linear thermal radiation over a horizontal porous stretching cylinder with potential applications in biomedical engineering. The present investigation utilised titanium dioxide and silver nanoparticles, which exhibit considerable potential in the realm of cancer therapy. Thus, there is a growing interest among biomedical engineers and clinicians in the study of entropy production as a means of quantifying energy dissipation in biological systems. Suitable self-similarity variables are employed to transform the nonlinear mathematical equations such as velocity, temperature, skin friction coefficient, and heat transfer rate, which are computed via homotopy perturbation method (HPM). HPM computations have been executed to solve the influences of various parameters such as porosity parameter ( K = 0.0 , 1.0 , 2.0 ) , Curvature parameter ( α = 0.0 , 1.0 , 3.0 , 5.0 ) , Casson parameter ( β = 0.0 , 0.5 , 1.5 ) , inertia coefficient ( F r = 0.5 , 1.5 , 2.5 ) , thermal relaxation parameter ( δ ∗ = 0.0 , 0.5 , 1.0 ) , radiation ( R d = 0.0 , 0.5 , 1.0 ) , Eckert number ( E c = 0.0 , 0.1 , 0.2 ) , Brinkman number ( B r = 0.5 , 1.0 , 1.5 ) and temperature difference parameter ( α 1 = 0.0 , 0.5 , 1.0 ) . The comparison using the homotopy perturbation technique produces a more accurate and reliable consequence than the numerical method (Runge-Kutta method). The higher values of the Casson and Curvature parameters decrease the velocity profile. The temperature profile of M = 1 and M = 0 increases with improving values of the thermal relaxation parameter. Entropy generation rises to enhance Brinkman number values, whereas Bejan number exhibits the reverse influence. Improving the value of the heat source parameter declines the Nusselt number.

Electronic Cigarette Vaping with Nicotine Causes Increased Thrombogenicity and Impaired Microvascular Function in Healthy Volunteers: A Randomised Clinical Trial

Electronic cigarette (EC) vaping is increasingly popular, despite growing evidence of adverse health effects. To further evaluate the impact of EC use on vascular health, we investigated the effects of brief EC inhalation on flow-dependent thrombus formation and microcirculation in healthy volunteers. The study was performed with a randomised double-blind crossover design. Twenty-two healthy subjects aged between 18 and 45 years with occasional tobacco use were recruited. Subjects inhaled 30 puffs of EC aerosol with and without nicotine on two occasions separated by a wash-out period of at least 1 week. Blood samples were collected at baseline and at 15 and 60 min following exposure and analysed with the Total-Thrombus-formation analysis system evaluating fibrin-rich thrombus formation and platelet thrombus formation in whole blood under flow. Microvascular function was assessed at baseline and 30 min after exposure by laser speckle contrast imaging and iontophoresis of acetylcholine and sodium nitroprusside (SNP) to evaluate the endothelium-dependent and independent pathways of vasodilation. Compared with nicotine free EC aerosol, exposure to EC aerosol with nicotine significantly increased platelet thrombus formation and fibrin-rich thrombus formation at 15 min (p = 0.017 and p = 0.037, respectively) with normalisation after 60 min. Peak SNP-mediated microvascular perfusion, i.e. endothelium-independent vasodilation, was reduced following EC vaping with nicotine compared with baseline (p = 0.006). Thirty puffs of EC aerosol with nicotine increased platelet and fibrin-dependent thrombus formation and reduced microvascular dilatation capacity. No compelling effects of EC vaping without nicotine were observed, indicating nicotine as the main effector. Trial registration: ClinicalTrials.gov Identifier: NCT04175457 URL: https://clinicaltrials.gov/ct2/show/NCT04175457.

Mechanisms of Cardiovascular Changes of Phototherapy in Newborns with Hyperbilirubinemia

During phototherapy of jaundiced newborns, vasodilation occurs in the skin circulation compensated by vasoconstriction in the renal and mesenteric circulation. Furthermore, there is a slight decrease in cardiac systolic volume, and blood pressure, as well as an increase in heart rate and discrete changes in the heart rate variability (HRV). The primary change during phototherapy is the skin vasodilation mediated by multiple mechanisms: 1) Passive vasodilation induced by direct skin heating effect of the body surface and subcutaneous blood vessels, modified by myogenic autoregulation. 2) Active vasodilation mediated via the mechanism provided by axon reflexes through nerve C-fibers and humoral mechanism via nitric oxide (NO) and endothelin 1 (ET-1). During and after phototherapy is a rise in the NO:ET-1 ratio. 3) Regulation of the skin circulation through the sympathetic nerves is unique, but their role in skin vasodilation during phototherapy was not studied. 4) Special mechanism is a photorelaxation independent of the skin heating. Melanopsin (opsin 4) - is thought to play a major role in systemic vascular photorelaxation. Signalling cascade of the photorelaxation is specific, independent of endothelium and NO. The increased skin blood flow during phototherapy is enabled by the restriction of blood flow in the renal and mesenteric circulation. An increase in heart rate indicates activation of the sympathetic system as is seen in the measures of the HRV. High-pressure, as well as low-pressure baroreflexes, may play important role in these adaptation responses. The integrated complex and specific mechanism responsible for the hemodynamic changes during phototherapy confirm adequate and functioning regulation of the neonatal cardiovascular system, including baroreflexes.

Elevations in sweat sodium concentration following ischemia-reperfusion injury during passive heat stress

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.

Mechanisms of skin vascular maturation and maintenance captured by longitudinal imaging of live mice

A functional network of blood vessels is essential for organ growth and homeostasis, yet how the vasculature matures and maintains homeostasis remains elusive in live mice. By longitudinally tracking the same neonatal endothelial cells (ECs) over days to weeks, we found that capillary plexus expansion is driven by vessel regression to optimize network perfusion. Neonatal ECs rearrange positions to evenly distribute throughout the developing plexus and become positionally stable in adulthood. Upon local ablation, adult ECs survive through a plasmalemmal self-repair response, while neonatal ECs are predisposed to die. Furthermore, adult ECs reactivate migration to assist vessel repair. Global ablation reveals coordinated maintenance of the adult vascular architecture that allows for eventual network recovery. Lastly, neonatal remodeling and adult maintenance of the skin vascular plexus are orchestrated by temporally restricted, neonatal VEGFR2 signaling. Our work sheds light on fundamental mechanisms that underlie both vascular maturation and adult homeostasis in vivo.

Imbalance of Peripheral Temperature, Sympathovagal, and Cytokine Profile in Long COVID

A persistent state of inflammation has been reported during the COVID-19 pandemic. This study aimed to assess short-term heart rate variability (HRV), peripheral body temperature, and serum cytokine levels in patients with long COVID. We evaluated 202 patients with long COVID symptoms categorized them according to the duration of their COVID symptoms (≤120 days, n = 81; >120 days, n = 121), in addition to 95 healthy individuals selected as controls. All HRV variables differed significantly between the control group and patients with long COVID in the ≤120 days group (p < 0.05), and participants in the long COVID ≤120 days group had higher temperatures than those in the long COVID >120 days group in all regions analysed (p < 0.05). Cytokine analysis showed higher levels of interleukin 17 (IL-17) and interleukin 2 (IL-2), and lower levels of interleukin 4 (IL-4) (p < 0.05). Our results suggest a reduction in parasympathetic activation during long COVID and an increase in body temperature due to possible endothelial damage caused by the maintenance of elevated levels of inflammatory mediators. Furthermore, high serum levels of IL-17 and IL-2 and low levels of IL-4 appear to constitute a long-term profile of COVID-19 cytokines, and these markers are potential targets for long COVID-treatment and prevention strategies.

Wound pH and temperature as predictors of healing: an observational study

OBJECTIVE

The aim of this study was to measure wound pH, wound temperature and wound size together to gain further understanding of their impact as predictors of wound healing outcomes.

METHOD

This study employed a quantitative non-comparative, prospective, descriptive observational design. Participants with both acute and hard-to-heal (chronic) wounds were observed weekly for four weeks. Wound pH was measured using pH indicator strips, wound temperature was measured using an infrared camera and wound size was measured using the ruler method.

RESULTS

Most of the 97 participants (65%, n=63) were male; participant's ages ranged between 18 and 77 years (mean: 42±17.10. Most of the wounds observed were surgical 60%, (n=58) and 72% (n=70) of the wounds were classified as acute, with 28% (n=27) classified as hard-to-heal wounds. At baseline, there was no significant difference in pH between acute and hard-to-heal wounds; overall the mean pH was 8.34±0.32, mean temperature was 32.86±1.78°C) and mean wound area was 910.50±1132.30mm2. In week 4, mean pH was 7.71±1.11, mean temperature was 31.90±1.76°C and mean wound area was 339.90±511.70mm2. Over the study follow-up period, wound pH ranged from 5-9, from week 1 to week 4, mean pH reduced by 0.63 units from 8.34 to 7.71. Furthermore, there was a mean 3% reduction in wound temperature and a mean 62% reduction in wound size.

CONCLUSION

The study demonstrated that a reduction in pH and temperature was associated with increased wound healing as evidenced by a corresponding reduction in wound size. Thus, measuring pH and temperature in clinical practice may provide clinically meaningful data pertaining to wound status.

A Preliminary Study of the Efficacy of Using a Wrist-Worn Multiparameter Sensor for the Prediction of Cognitive Flow States in University-Level Students

Engagement is enhanced by the ability to access the state of flow during a task, which is described as a full immersion experience. We report two studies on the efficacy of using physiological data collected from a wearable sensor for the automated prediction of flow. Study 1 took a two-level block design where activities were nested within its participants. A total of five participants were asked to complete 12 tasks that aligned with their interests while wearing the Empatica E4 sensor. This yielded 60 total tasks across the five participants. In a second study representing daily use of the device, a participant wore the device over the course of 10 unstructured activities over 2 weeks. The efficacy of the features derived from the first study were tested on these data. For the first study, a two-level fixed effects stepwise logistic regression procedure indicated that five features were significant predictors of flow. In total, two were related to skin temperature (median change with respect to the baseline and skewness of the temperature distribution) and three were related to acceleration (the acceleration skewness in the x and y directions and the kurtosis of acceleration in the y direction). Logistic regression and naïve Bayes models provided a strong classification performance (AUC > 0.7, between-participant cross-validation). For the second study, these same features yielded a satisfactory prediction of flow for the new participant wearing the device in an unstructured daily use setting (AUC > 0.7, leave-one-out cross-validation). The features related to acceleration and skin temperature appear to translate well for the tracking of flow in a daily use environment.

The impact of climate change on atopic dermatitis and mental health comorbidities: a review of the literature and examination of intersectionality

Climate change, fueled by increasing concentrations of greenhouse gases, is associated with rising temperatures, extreme weather events, increased aeroallergen production, and air pollution. Our understanding that many inflammatory cutaneous diseases carry important mental health comorbidities is expanding. Simultaneously, the detrimental impacts of climate change on human health are now widely recognized as a global public health crisis. Importantly, these climate-associated phenomena exacerbate the environmental triggers of atopic dermatitis (AD) and are also associated with amplification of comorbid mental health conditions in AD including depression, anxiety, trauma-related disorders, and psychotic spectrum disorders. This review is the first to examine the nexus of climate change, atopic dermatitis, and mental health comorbidities and emphasizes the disproportionate impacts of climate change in vulnerable and marginalized populations.

Interdependency of Core Temperature and Glabrous Skin Blood Flow in Human Thermoregulation Function: A Pilot Study

Human thermoregulation is governed by a complex, nonlinear feedback control system. The system consists of thermoreceptors, a controller, and effector mechanisms for heat exchange that coordinate to maintain a central core temperature. A principal route for heat flow between the core and the environment is via convective circulation of blood to arteriovenous anastomoses located in glabrous skin of the hands and feet. This paper presents new human experimental data for thermoregulatory control behavior along with a coupled, detailed control system model specific to the interdependent actions of core temperature and glabrous skin blood flow (GSBF) under defined transient environmental thermal stress. The model was tuned by a nonlinear least-squared curve fitting algorithm to optimally fit the experimental data. Transient GSBF in the model is influenced by core temperature, nonglabrous skin temperature, and the application of selective thermal stimulation. The core temperature in the model is influenced by integrated heat transfer across the nonglabrous body surface and GSBF. Thus, there is a strong cross-coupling between GSBF and core temperature in thermoregulatory function. Both variables include a projection term in the model based on the average rates of their change. Six subjects each completed two thermal protocols to generate data to which the common model was fit. The model coefficients were unique to each of the twelve data sets but produced an excellent agreement between the model and experimental data for the individual trials. The strong match between the model and data confirms the mathematical structure of the control algorithm.

Influence of topical capsaicin cream on thermoregulation and perception during acute exercise in the heat

PURPOSE

Determine if topical capsaicin, a transient receptor potential vanilloid heat thermoreceptor activator, alters thermoregulation and perception when applied topically prior to thermal exercise.

METHODS

Twelve subjects completed 2 treatments. Subjects walked (1.6 m s^-1, 5% grade) for 30 min in the heat (38 °C, 60% relative humidity) with either a capsaicin (0.025% capsaicin) or control cream applied to the upper (shoulder to wrist) and lower (mid-thigh to ankle) limbs covering ∼50% body surface area. Skin blood flow (SkBF), sweat (rate, composition), heart rate, temperature (skin, core), and perceived thermal sensation were measured prior to and during exercise.

RESULTS

The relative change in SkBF was not different between treatments at any time point (p = 0.284). There were no differences in sweat rate between the capsaicin (1.23 ± 0.37 L h^-1) and control (1.43 ± 0.43 L h^-1, p = 0.122). There were no differences in heart rate between the capsaicin (122 ± 38 beats·min^-1) and control (125 ± 39 beats·min^-1, p = 0.431). There were also no differences in weighted surface (p = 0.976) or body temperatures (p = 0.855) between the capsaicin (36.0 ± 1.7 °C, 37.0 ± 0.8 °C, respectively) and control (36.0 ± 1.6 °C, 36.9 ± 0.8 °C, respectively). The capsaicin treatment was not perceived as hotter than the control treatment until minute 30 of exercise (2.8 ± 0.4, 2.5 ± 0.5, respectively, p = 0.038) CONCLUSIONS: Topical capsaicin application does not alter whole-body thermoregulation during acute exercise in the heat despite perceiving the treatment as hotter late in exercise.

Transcriptomic Heterogeneity of Skin Across Different Anatomic Sites

Multiomic studies, including RNA sequencing, single-cell RNA sequencing, and epigenomics, can provide insight into the connection between anatomically heterogeneous gene expression profile of the skin and dermatoses-predisposed sites, in which RNA sequencing is essential. Therefore, in this study, 159 skin samples collected mainly from discarded normal skin tissue during surgical treatment for benign skin tumors were used for RNA sequencing. On the basis of cluster analysis, the skin was divided into four regions, with each region showing specific physiological characteristics through differentially expressed gene analysis. The results showed that the head and neck region, perineum, and palmoplantar area were closely associated with lipid metabolism, hormone metabolism, blood circulation, and related neural regulation, respectively. Transcription factor enrichment indicated that different regions were associated with the development of adjacent tissues. Specifically, the head and neck region, trunk and extremities, perineum, and palmoplantar area were associated with the central nervous, axial, urogenital, and vascular systems, respectively. The results were imported into an open website (https://dermvis.github.io/) for retrieval. Our transcriptomic data elucidated that human skin exhibits transcriptomic heterogeneity reflecting physiological and developmental variation at different anatomic sites and provided guidance for further studies on skin development and dermatoses predisposed sites.

Wireless, AI-enabled wearable thermal comfort sensor for energy-efficient, human-in-the-loop control of indoor temperature

The conventional heating, ventilation, and air conditioning (HVAC) systems are based on a set-point control approach that only considers the temperature of the environment without reflecting the thermophysiological status of the occupant. This approach not only fails to fully satisfy individual thermal preferences, but it also makes an HVAC operation energy-inefficient. One possible solution is to control the indoor thermal condition based on an accurate prediction of the occupant's thermal comfort to prevent any unnecessary energy consumption. Here, we present an artificial intelligence (AI) wearable sensor-based human-in-the-loop HVAC control system that is operated on a real-time basis reflecting the thermophysiological condition of the occupant to automatically improve their thermal comfort while reducing the energy consumption of the building. The wristband-type, AI-based, three-point wearable temperature sensor offers excellent thermal comfort prediction accuracy (93.9%), enabling a human-centric HVAC control operation. A proof-of-concept demonstration of closed human-in-the-loop HVAC control using the AI-enabled wearable sensor system confirms both the accuracy of the thermal comfort prediction and the energy-efficiency of this approach, demonstrating its potential as a new solution that improves the occupant's thermal comfort and provides building energy savings.

Pilot study of optical coherence tomography angiography-derived microvascular metrics in hands and feet of healthy and diabetic people

Optical coherence tomography angiography (OCTA) is a non-invasive, high-resolution imaging modality with growing application in dermatology and microvascular assessment. Accepted reference values for OCTA-derived microvascular parameters in skin do not yet exist but need to be established to drive OCTA into the clinic. In this pilot study, we assess a range of OCTA microvascular metrics at rest and after post-occlusive reactive hyperaemia (PORH) in the hands and feet of 52 healthy people and 11 people with well-controlled type 2 diabetes mellitus (T2DM). We calculate each metric, measure test-retest repeatability, and evaluate correlation with demographic risk factors. Our study delivers extremity-specific, age-dependent reference values and coefficients of repeatability of nine microvascular metrics at baseline and at the maximum of PORH. Significant differences are not seen for age-dependent microvascular metrics in hand, but they are present for several metrics in the foot. Significant differences are observed between hand and foot, both at baseline and maximum PORH, for most of the microvascular metrics with generally higher values in the hand. Despite a large variability over a range of individuals, as is expected based on heterogeneous ageing phenotypes of the population, the test-retest repeatability is 3.5% to 18% of the mean value for all metrics, which highlights the opportunities for OCTA-based studies in larger cohorts, for longitudinal monitoring, and for assessing the efficacy of interventions. Additionally, branchpoint density in the hand and foot and changes in vessel diameter in response to PORH stood out as good discriminators between healthy and T2DM groups, which indicates their potential value as biomarkers. This study, building on our previous work, represents a further step towards standardised OCTA in clinical practice and research.

Comparison of Slate Safety Wearable Device to Ingestible Pill and Wearable Heart Rate Monitor

BACKGROUND

With the increase in concern for deaths and illness related to the increase in temperature globally, there is a growing need for real-time monitoring of workers for heat stress indicators. The purpose of this study was to determine the usability of the Slate Safety (SS) wearable physiological monitoring system.

METHODS

Twenty nurses performed a common task in a moderate or hot environment while wearing the SS device, the Polar 10 monitor, and having taken the e-Celsius ingestible pill. Data from each device was compared for correlation and accuracy.

RESULTS

High correlation was determined between the SS wearable device and the Polar 10 system (0.926) and the ingestible pill (0.595). The SS was comfortable to wear and easily monitored multiple participants from a distance.

CONCLUSIONS

The Slate Safety wearable device demonstrated accuracy in measuring core temperature and heart rate while not restricting the motion of the worker, and provided a remote monitoring platform for physiological parameters.

Sex differences in thermoregulation in mammals: Implications for energy homeostasis

Thermal homeostasis is a fundamental process in mammals, which allows the maintenance of a constant internal body temperature to ensure an efficient function of cells despite changes in ambient temperature. Increasing evidence has revealed the great impact of thermoregulation on energy homeostasis. Homeothermy requires a fine regulation of food intake, heat production, conservation and dissipation and energy expenditure. A great interest on this field of research has re-emerged following the discovery of thermogenic brown adipose tissue and browning of white fat in adult humans, with a potential clinical relevance on obesity and metabolic comorbidities. However, most of our knowledge comes from male animal models or men, which introduces unwanted biases on the findings. In this review, we discuss how differences in sex-dependent characteristics (anthropometry, body composition, hormonal regulation, and other sexual factors) influence numerous aspects of thermal regulation, which impact on energy homeostasis. Individuals of both sexes should be used in the experimental paradigms, considering the ovarian cycles and sexual hormonal regulation as influential factors in these studies. Only by collecting data in both sexes on molecular, functional, and clinical aspects, we will be able to establish in a rigorous way the real impact of thermoregulation on energy homeostasis, opening new avenues in the understanding and treatment of obesity and metabolic associated diseases.

Advanced thermal sensing techniques for characterizing the physical properties of skin

Measurements of the thermal properties of the skin can serve as the basis for a noninvasive, quantitative characterization of dermatological health and physiological status. Applications range from the detection of subtle spatiotemporal changes in skin temperature associated with thermoregulatory processes, to the evaluation of depth-dependent compositional properties and hydration levels, to the assessment of various features of microvascular/macrovascular blood flow. Examples of recent advances for performing such measurements include thin, skin-interfaced systems that enable continuous, real-time monitoring of the intrinsic thermal properties of the skin beyond its superficial layers, with a path to reliable, inexpensive instruments that offer potential for widespread use as diagnostic tools in clinical settings or in the home. This paper reviews the foundational aspects of the latest thermal sensing techniques with applicability to the skin, summarizes the various devices that exploit these concepts, and provides an overview of specific areas of application in the context of skin health. A concluding section presents an outlook on the challenges and prospects for research in this field.

Benincasa hispida extracts positively regulated high salt-induced hypertension in Dahl salt-sensitive rats: Impact on biochemical profile and metabolic patterns

Salt-induced hypertension is one of the major issues worldwide and one of the main factors involved in heart and kidney failure. The objective of this study was to investigate the potential role of Benincasa hispida extracts on high salt-induced hypertension in Dahl-salt sensitive (D-SS) rats and to find out the metabolic and biochemical pattern involved in the reduction of hypertension. Twenty-six Dahl salt-sensitive (D-SS) rats were selected and divided into four groups. The metabolic strategy was applied to test the extracts on salt-sensitive hypertension in kidney. Gas Chromatography-Mass spectrometry (GC-MS) was used to identify the potent biochemical profile in renal medulla and cortex of rat kidneys. The differential metabolites of cortex and medulla, enrichment analysis and pathway analysis were performed using metabolomics data. The GC-MS data revealed that 24 different antihypertensive metabolites was detected in renal cortex, while 16 were detected in renal medulla between different groups. The significantly metabolic pathways namely citrate cycle, glutathione metabolism, glycine, serine, and threonine metabolism, glyoxylate and dicarboxylate metabolism, glycerolipid metabolism, alanine, aspartate and glutamate metabolism in renal cortex and glycerolipid metabolism, pentose phosphate pathway, citrate cycle, glycolysis, glycerophospholipid metabolism, phenylalanine, tyrosine and tryptophan biosynthesis in renal medulla were involved in the process of Hypertension. The results suggest that the extract mainly alter the metabolic pathways of amino acid in Dahl salt-sensitive rats and its antioxidant potential reduced the hypertension patterns of Salt-sensitive rat. The antihypertensive components malic acid, aspartic acid, and glycine of extract can be used as therapeutic drugs to protect kidneys from salt-induced hypertension. PRACTICAL APPLICATIONS: Hypertension is a multifactorial disease and one of the risk factors for heart and kidney failure. Benincasa hispida is a widely used vegetable in China, which belongs to the Cucurbitaceae family. Benincasa hispida (wax gourd) has been used in traditional Chinese medicine for the treatment of inflammation and hypertension. The Benincasa hispida contains many compounds such as amino acids, carbohydrates, volatile compounds, vitamins, and minerals. The amino acid present in the pulp of Benincasa hispida are ornithine, threonine, aspartate, glutamate, serine, glycine, proline, alanine, valine, cysteine, isoleucine, tyrosine, leucine, lysine, phenylalanine, histidine, arginine, and γ-aminobutyric acid. Our results showed that Benincasa hispida is one of the potent natural antioxidants and can maintain normal blood pressure in Dahl salt-sensitive rats (D-SS). In conclusion, the current results provide good theoretical basis for the development and research using Benincasa hispida as an effective natural antioxidant for hypertension.

Climate change and the prevention of cardiovascular disease

Climate change is a worsening global crisis that will continue negatively impacting population health and well-being unless adaptation and mitigation interventions are rapidly implemented. Climate change-related cardiovascular disease is mediated by air pollution, increased ambient temperatures, vector-borne disease and mental health disorders. Climate change-related cardiovascular disease can be modulated by climate change adaptation; however, this process could result in significant health inequity because persons and populations of lower socioeconomic status have fewer adaptation options. Clear scientific evidence for climate change and its impact on human health have not yet resulted in the national and international impetus and policies necessary to slow climate change. As respected members of society who regularly communicate scientific evidence to patients, clinicians are well-positioned to advocate on the importance of addressing climate change. This narrative review summarizes the links between climate change and cardiovascular health, proposes actionable items clinicians and other healthcare providers can execute both in their personal life and as an advocate of climate policies, and encourages communication of the health impacts of climate change when counseling patients. Our aim is to inspire the reader to invest more time in communicating the most crucial public health issue of the 21st century to their patients.

Vasodilatory effects of glucagon: A possible new approach to enhanced subcutaneous insulin absorption in artificial pancreas devices

Patients with diabetes mellitus type 1 depend on exogenous insulin to keep their blood glucose concentrations within the desired range. Subcutaneous bihormonal artificial pancreas devices that can measure glucose concentrations continuously and autonomously calculate and deliver insulin and glucagon infusions is a promising new treatment option for these patients. The slow absorption rate of insulin from subcutaneous tissue is perhaps the most important factor preventing the development of a fully automated artificial pancreas using subcutaneous insulin delivery. Subcutaneous insulin absorption is influenced by several factors, among which local subcutaneous blood flow is one of the most prominent. We have discovered that micro-doses of glucagon may cause a substantial increase in local subcutaneous blood flow. This paper discusses how the local vasodilative effects of micro-doses of glucagon might be utilised to improve the performance of subcutaneous bihormonal artificial pancreas devices. We map out the early stages of our hypothesis as a disruptive novel approach, where we propose to use glucagon as a vasodilator to accelerate the absorption of meal boluses of insulin, besides using it conventionally to treat hypoglycaemia.

Glomerular filtration rate reserve is reduced during mild passive heat stress in healthy young adults

We tested the hypothesis that, compared with normothermia, the increase in glomerular filtration rate (GFR) after an oral protein load (defined as the GFR reserve) is attenuated during moderate passive heat stress in young healthy adults. Sixteen participants (5 women; 26 ± 2 yr) completed two experimental visits, heat stress or a normothermic time-control, assigned in a block-randomized crossover design. During the heat stress trial, core temperature was increased by 0.6°C in the first hour before commencing a 2-min cold pressor test (CPT) to assess renal vasoconstrictor responses. One-hour post-CPT, subjects ingested a whey protein shake (1.2 g of protein/kg body wt), and measurements were taken pre-, 75, and 150 min postprotein. Segmental artery vascular resistance was calculated as the quotient of Doppler ultrasound-derived segmental artery blood velocity and mean arterial pressure and provided an estimate of renal vascular tone. GFR was estimated from creatinine clearance. The increase in segmental artery vascular resistance during the CPT was attenuated during heat stress (end CPT: 5.6 ± 0.9 vs. 4.7 ± 1.1 mmHg/cm/s, P = 0.024). However, the reduction in segmental artery vascular resistance in response to an oral protein load did not differ between heat stress (at 150 min: 1.9 ± 0.4 mmHg/cm/s) and normothermia (at 150 min: 1.8 ± 0.5 mmHg/cm/s; P = 0.979). The peak increase in creatinine clearance postprotein, independent of time, was attenuated during heat stress (+26 ± 19 vs. +16 ± 20 mL/min, P = 0.013, n = 13). GFR reserve is diminished by mild passive heat stress. Moreover, renal vasoconstrictor responses are attenuated by mild passive heat stress, but renal vasodilator responses are maintained.

Development of a self-monitoring tool for diabetic foot prevention using smartphone-based thermography: Plantar thermal pattern changes and usability in the home environment

Thermography is a well-known risk-assessment tool for diabetic foot ulcers but is not widely used in the home setting due to the influence of the complicated home environment on thermographic images. This study investigated changes in thermographic images in complicated home environments to determine the feasibility of smartphone-based thermography in home settings. Healthy volunteers (age > 20 years) were recruited and required to take plantar thermal images using smartphone-based thermography attached to a selfie stick at different times of the day for 4 days. The thermal images and associated activities and environmental factors were then analyzed using content analysis. Areas with the highest temperature on the plantar thermal images were described and categorized. Device usability was evaluated using 10-point Likert scales, with 10 representing the highest satisfaction. A total of 140 plantar thermal images from 10 participants were analyzed. In 12 classifications, the three commonest patterns based on the highest temperature location were medial arch (42.1%), whole plantar (10.7%), and forefoot and medial arch (7.9%). The medial arch pattern is most frequently seen after awakening (67.5%) compared to other time points. Device usability was rated 7.5 out of 10 on average. This study was the first to investigate the plantar thermal patterns in the home settings, and the medial arch pattern was the most common hot area, which matches previous findings in well-controlled clinical settings. Therefore, smartphone-based thermography may be feasible as a self-assessment tool in the home setting.

Do ginger footbaths improve symptoms of insomnia more than footbaths with warm water only? - A randomized controlled study

OBJECTIVES

To compare the effects between warm water (WW) and ginger footbaths (WW+ginger) on sleep quality and warmth regulation in adults with self-reported insomnia symptoms.

METHODS

A prospective randomized-controlled study in which 28 participants (mean age 50.9 years, 64.3% women, insomnia symptom duration 11.4 years) were randomized to receive WW (n = 13) or WW+ginger (n = 15) daily for 2 weeks. Treatment involved nightly footbaths (12 liters of 38-42 °C warm tap water, maximum duration 20 min) with and without topical ginger (80 g of powdered ginger rhizomes).

MAIN OUTCOME MEASURES

The primary outcome measure was self-reported sleep quality (global score from Pittsburgh Sleep Quality Index, PSQI) at 2 weeks. Secondary outcomes included measures of insomnia severity (Insomnia Severity Index, ISI) and warmth regulation (Herdecke Warmth Perception Questionnaire, HWPQ and 24-hour distal-proximal skin temperature gradient, DPG).

RESULTS

WW+ginger had no greater effect on PSQI (mean between-difference 0.0 [95% CI -3.0 to 2.9], Cohen's d=0.0) or ISI (-0.2 [-3.9 to 3.4], 0.0) than WW. Nor were there any significant differences in HWPQ perceived warmth (0.1 ≥d≥0.5) or DPG (0.1 ≥d≥0.4) between WW and WW+ginger. Both groups improved over time in PSQI (WW+ginger: d=0.7, WW: d=1.3) and ISI (WW+ginger: d=0.8, WW: d=1.0). Perceived warmth of the feet increased only in WW+ginger over time (d=0.6, WW: d=0.0).

CONCLUSIONS

This dose of ginger (6.67 g/liter) did not have greater effects on sleep quality, insomnia severity or warmth regulation than WW. Considering effect sizes, costs and risks, the use of WW would be recommended over WW+ginger in this patient population.

Diffuse correlation spectroscopy blood flow monitoring for intraventricular hemorrhage vulnerability in extremely low gestational age newborns

In premature infants with an extremely low gestational age (ELGA, < 29 weeks GA), dysregulated changes in cerebral blood flow (CBF) are among the major pathogenic factors leading to germinal matrix/intraventricular hemorrhage (GM/IVH). Continuous monitoring of CBF can guide interventions to minimize the risk of brain injury, but there are no clinically standard techniques or tools for its measurement. We report the feasibility of the continuous monitoring of CBF, including measures of autoregulation, via diffuse correlation spectroscopy (DCS) in ELGA infants using CBF variability and correlation with scalp blood flow (SBF, served as a surrogate measure of systemic perturbations). In nineteen ELGA infants (with 9 cases of GM/IVH) monitored for 6–24 h between days 2–5 of life, we found a strong correlation between CBF and SBF in severe IVH (Grade III or IV) and IVH diagnosed within 72 h of life, while CBF variability alone was not associated with IVH. The proposed method is potentially useful at the bedside for the prompt assessment of cerebral autoregulation and early identification of infants vulnerable to GM/IVH.

Characteristics of Kundalini-Related Sensory, Motor, and Affective Experiences During Tantric Yoga Meditation

Traditional spiritual literature contains rich anecdotal reports of spontaneously arising experiences occurring during meditation practice, but formal investigation of such experiences is limited. Previous work has sometimes related spontaneous experiences to the Indian traditional contemplative concept of kundalini. Historically, descriptions of kundalini come out of Tantric schools of Yoga, where it has been described as a “rising energy” moving within the spinal column up to the brain. Spontaneous meditation experiences have previously been studied within Buddhist and Christian practices and within eclectic groups of contemplative practitioners. Prior explorations of kundalini have emphasized extreme experiences, sometimes having clinical consequences. We conducted a first such investigation of kundalini-related experiences within a sample of meditators from a single Tantric Yoga tradition (known as Ananda Marga) that emphasizes the role of kundalini. We developed a semi-structured questionnaire to conduct an exploratory pilot investigation of spontaneous sensory, motor and affective experiences during meditation practice. In addition to identifying the characteristics of subjective experiences, we measured quantity of meditation, supplemental practices, trait affect and trait mindfulness. We administered it to 80 volunteers at two Ananda Marga retreats. Among reported experiences, we found the highest prevalence for positive mood shifts, followed by motor and then sensory experiences. The frequency of spontaneous experiences was not related to the quantity of practiced meditation or trait measures of mindfulness and affect. Self-reports included multiple descriptions of rising sensations, sometimes being directly called kundalini. Experiences with rising sensations were complex and many included references to positive affect, including ecstatic qualities. There were also reports of spontaneous anomalous experiences. These experiences of rising sensations resemble prior clinical descriptions that were considered kundalini-related. The individuals who reported rising sensations could not be distinguished from other participants based on the incidence of experiences, quantity of meditation practice, or trait measures of mindfulness and affect. In contrast, greater amount of Tantric Yoga meditation practice was associated with greater positive affect, less negative affect and greater mindfulness. Further study of these exploratory findings and how they may be related to spiritual and well-being goals of meditation is warranted along with scientific investigation of purported kundalini phenomena.

Does the Heel’s Dissipative Energetic Behavior Affect Its Thermodynamic Responses During Walking?

Most of the terrestrial legged locomotion gaits, like human walking, necessitate energy dissipation upon ground collision. In humans, the heel mostly performs net-negative work during collisions, and it is currently unclear how it dissipates that energy. Based on the laws of thermodynamics, one possibility is that the net-negative collision work may be dissipated as heat. If supported, such a finding would inform the thermoregulation capacity of human feet, which may have implications for understanding foot complications and tissue damage. Here, we examined the correlation between energy dissipation and thermal responses by experimentally increasing the heel’s collisional forces. Twenty healthy young adults walked overground on force plates and for 10 min on a treadmill (both at 1.25 ms−1) while wearing a vest with three different levels of added mass (+0%, +15%, &amp; +30% of their body mass). We estimated the heel’s work using a unified deformable segment analysis during overground walking. We measured the heel’s temperature immediately before and after each treadmill trial. We hypothesized that the heel’s temperature and net-negative work would increase when walking with added mass, and the temperature change is correlated with the increased net-negative work. We found that walking with +30% added mass significantly increased the heel’s temperature change by 0.72 ± 1.91 ℃ (p = 0.009) and the magnitude of net-negative work (extrapolated to 10 min of walking) by 326.94 ± 379.92 J (p = 0.005). However, we found no correlation between the heel’s net-negative work and temperature changes (p = 0.277). While this result refuted our second hypothesis, our findings likely demonstrate the heel’s dynamic thermoregulatory capacity. If all the negative work were dissipated as heat, we would expect excessive skin temperature elevation during prolonged walking, which may cause skin complications. Therefore, our results likely indicate that various heat dissipation mechanisms control the heel’s thermodynamic responses, which may protect the health and integrity of the surrounding tissue. Also, our results indicate that additional mechanical factors, besides energy dissipation, explain the heel’s temperature rise. Therefore, future experiments may explore alternative factors affecting thermodynamic responses, including mechanical (e.g., sound &amp; shear-stress) and physiological mechanisms (e.g., sweating, local metabolic rate, &amp; blood flow).