The sympathetic release test: a test used to assess thermoregulation and autonomic control of blood flow

Exploring the Predictive Potential of Physiological Measures of Human Thermal Strain in Outdoor Environments in Hot and Humid Areas in Summer-A Case Study of Shanghai, China

Whenever people spend time outdoors during hot weather, they are putting themselves in potentially stressful situations. Being able to predict whether a person is overheating can be critical in preventing heat-health issues. There is a clear relationship between body core temperature and heat health. However, measuring body core temperature is expensive. Identifying a non-invasive measure that could indicate a person's thermal strain would be valuable. This study investigated five physiological measures as possible surrogates: finger mean skin temperature (FSKT), finger maximum skin temperature (FMSKT), skin conductance level (SCL), heart rate (HR), and heart rate variability (HRV). Furthermore, they were compared against the results of participants' subjective thermal sensation and thermal comfort in a range of hot microclimatic conditions in a hot and humid climate. Results showed that except for SCL, each of the other four physiological measures had a positive significant relationship with thermal sensation, but a negative relationship with thermal comfort. Furthermore, through testing by cumulative link mixed models, HRV was found to be the most suitable surrogate for predicting thermal sensation and thermal comfort through a simple, non-invasive measure in outdoor environment in summer in a hot and humid area. This study highlights the method for predicting human thermal strain and contributes to improve the public health and well-being of urban dwellers in outdoor environments.

Psychophysiology of positive and negative emotions, dataset of 1157 cases and 8 biosignals

Subjective experience and physiological activity are fundamental components of emotion. There is an increasing interest in the link between experiential and physiological processes across different disciplines, e.g., psychology, economics, or computer science. However, the findings largely rely on sample sizes that have been modest at best (limiting the statistical power) and capture only some concurrent biosignals. We present a novel publicly available dataset of psychophysiological responses to positive and negative emotions that offers some improvement over other databases. This database involves recordings of 1157 cases from healthy individuals (895 individuals participated in a single session and 122 individuals in several sessions), collected across seven studies, a continuous record of self-reported affect along with several biosignals (electrocardiogram, impedance cardiogram, electrodermal activity, hemodynamic measures, e.g., blood pressure, respiration trace, and skin temperature). We experimentally elicited a wide range of positive and negative emotions, including amusement, anger, disgust, excitement, fear, gratitude, sadness, tenderness, and threat. Psychophysiology of positive and negative emotions (POPANE) database is a large and comprehensive psychophysiological dataset on elicited emotions.

Facial temperature and pupil size as indicators of internal state in primates

Studies in human subjects have revealed that autonomic responses provide objective and biologically relevant information about cognitive and affective states. Measures of autonomic responses can also be applied to studies of non-human primates, which are neuro-anatomically and physically similar to humans. Facial temperature and pupil size are measured remotely and can be applied to physiological experiments in primates, preferably in a head-fixed condition. However, detailed guidelines for the use of these measures in non-human primates is lacking. Here, we review the neuronal circuits and methodological considerations necessary for measuring and analyzing facial temperature and pupil size in non-human primates. Previous studies have shown that the modulation of these measures primarily reflects sympathetic reactions to cognitive and emotional processes, including alertness, attention, and mental effort, over different time scales. Integrated analyses of autonomic, behavioral, and neurophysiological data in primates are promising methods that reflect multiple dimensions of emotion and could potentially provide tools for understanding the mechanisms underlying neuropsychiatric disorders and vulnerabilities characterized by cognitive and affective disturbances.

Effect of 660/850 nm LED on the microcirculation of the foot: neurovascular biphasic reflex

Phototherapy (LED) can be used to stimulate the healing of chronic ulcers of the lower limb, as it affects healing cells and neurons. In this way, this study has sought to know if the heat stimulus of the 660-/850-nm contact LED is sufficient to trigger the response in the peripheral sympathetic nervous system of normal volunteers. The LED was applied on the right foot of forty-two normal volunteers followed by serial infrared images. After the stimulus, a biphasic hyperthermia curve was observed synchronously in both feet, in the right and left halluxes, while hyperthermia was attributed to the redistribution of postural blood flow in the plantar region, which may indicate independent neurovascular mechanisms. Thus, periodic thermographic analysis can be used in the evolution of the LED treatment.

Plantar temperatures in stance position: A comparative study with healthy volunteers and diabetes patients diagnosed with sensoric neuropathy

Background

Microcirculatory defects in diabetes are linked with neuropathy and the onset of diabetic foot syndrome. In this study we quantify pressure- and posture-dependent changes of plantar temperatures as a surrogate of tissue perfusion in healthy volunteers versus diabetes patients diagnosed with neuropathy in the absence of macroangiopathy.

Methods

Healthy volunteers (n = 31) as well as patients with diabetes diagnosed with severe polyneuropathy (n = 30) were enrolled in a clinical study to test for plantar temperature changes in the feet during extended episodes of standing. These lasted between 5 and 20 min each over 95 min, in between the participants were asked to take a seated position for 5 min and release the pressure from the feet. Major macroangiopathy was excluded before study enrolment. Custom-made insoles harbored temperature and pressure sensors positioned at eight preselected positions for recording.

Findings

In both subgroups a significant plantar temperature downshift occurred within 10 min of standing, which was especially detected during the initial 45 min of the study protocol. Comparisons between healthy volunteers and patients with diabetes revealed no differences in the magnitude of temperature downshifts during stance episodes. Pressure sensor recordings revealed that healthy volunteers intermittently released pressure during the longer stance episodes due to discomfort, whereas the patients with diabetes and polyneuropathy did not.

Interpretation

Our findings demonstrate a tight plantar temperature regulation following pressure exposure. In patients with diabetes and peripheral sensoric neuropathy the temperature drop is similar to healthy volunteers. Potentially, prolonged stance periods resulting in less perfused plantar tissue may remain unrecognized with polyneuropathy, whereas discomfort develops in healthy controls.

Funding

The study was supported by EFRE Förderung der Europäischen Union und Landesmittel des Ministeriums für Wirtschaft, Wissenschaft und Digitalisierung Sachsen-Anhalt (Vorhabennummer: ZS/2016/05/78,615 and ZS/2018/12/95,325). JK and PRM were supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project ID 97,850,925 - SFB854, AM by the Chinese Scholarship Council (CSC).

Effects of hot foot and arm bath in bronchial asthma: A single case report

BACKGROUND

Managing the condition of corticosteroid resistant asthmatic patients is quite difficult and challenging despite the plethora of new and modern medications. Hot Foot and Arm Bath (HFAB) is a widely used treatment modality for the management of bronchial asthma in Naturopathy. However, no scientific documentation or study is available so far assessing its effectiveness.

CASE SUMMARY

A 33-year-old male was admitted to our hospital, with major complaints of wheezing and dyspnea for two weeks before admission, with a known case of asthma and occasional use of inhalers. Spirometry tests showed a reversible obstructive pattern (pre-bronchodilator FEV1, 1.64L; post-bronchodilator FEV1, 2.02L; reversibility, 16%). The patient underwent HFAB application for 3 days in the morning, and the pulmonary function test was recorded before and immediately after HFAB. The pulmonary function's parameters such as FVC, FEV1, FEV1/FVC ratio, PEF 25-75 %, and PEFR showed significant improvement immediately after the HFAB on day 2 and day 3 when compared to day 1.

CONCLUSIONS

The findings suggest that HFAB application has an immediate action on improving lung function in patients with bronchial asthma and could be used as effective adjuvant therapy for the management of bronchial asthma. This is the first case report on HFAB application for bronchial asthma and future extensive studies with a large population would validate our findings.

Effect of Landscape Microclimates on Thermal Comfort and Physiological Wellbeing

Global climate change and intensifying heat islands have reduced human thermal comfort and health in urban outdoor environments. However, there has been little research that has focused on how microclimates affect human thermal comfort, both psychologically and physiologically. We investigated the effect of a range of landscape microclimates on human thermal comfort and health using questionnaires and physiological measurements, including skin temperature, skin conductance, and heart rate variability, and compared the results with the effect of prevailing climate conditions in open spaces. We observed that in landscape microclimates, thermal sensation votes significantly decreased from 1.18 ± 0.66 (warm–hot) to 0.23 ± 0.61 (neutral–slightly warm), and thermal comfort increased from 1.18 ± 0.66 (uncomfortable–neutral) to 0.23 ± 0.61 (neutral–comfortable). In the landscape microclimates, skin temperature and skin conductance decreased 0.3 ± 0.8 °C and 0.6 ± 1.0 μs, respectively, while in the control, these two parameters increased by 0.5 ± 0.9 °C and 0.2 ± 0.7 μs, respectively. Further, in landscape microclimates, subject heart rate variability increased significantly. These results suggest landscape microclimates improve human thermal comfort and health, both psychologically and physiologically. These findings can provide an evidence base that will assist urban planners in designing urban environments for the health and wellbeing of residents.

Naturopathic Treatment and Complementary Medicine in Surgical Practice

BACKGROUND

Many patients in Germany use naturopathic treatments and complementary medicine. Surveys have shown that many also use them as a concomitant treatment to surgery.

METHODS

Multiple databases were systematically searched for systematic reviews, controlled trials, and experimental studies concerning the use of naturopathic treatments and complementary medicine in the management of typical post-operative problems (PROSPERO CRD42018095330).

RESULTS

Of the 387 publications identified by the search, 76 fulfilled the inclusion criteria. In patients with abnormal gastrointestinal activity, acupuncture can improve motility, ease the passing of flatus, and lead to earlier defecation. Acupuncture and acupressure can reduce postoperative nausea and vomiting, as well as pain. More-over,aromatherapy and music therapy seem to reduce pain, stress and anxiety and to improve sleep. Further studies are needed to determine whether phytotherapeutic treatments are effective for the improvement of gastrointestinal function or the reduction of stress. It also remains unclear whether surgical patients can benefit from the methods of mind body medicine.

CONCLUSION

Certain naturopathic treatments and complementary medical methods may be useful in postoperative care and deserve more intensive study. In the publications consulted for this review, no serious side effects were reported.

The range of normative surface skin temperature changes in adolescents: prospective multicenter study

AIM

We aimed to establish a normative range of surface skin temperature (SST) changes due to blood redistribution in adolescents and to register the time needed for complete postural change-related blood redistribution.

METHODS

The healthy volunteers (age 15-18, n = 500, M 217, F 283) were recruited for this prospective multicenter study. The volunteers were asked to keep one extremity down and another extremity up in supine rest, sitting with straight legs, and upright rest. We obtained temperature readings being taken from the tips of the middle fingers and temperature readings from the tips of the first toes at the ambient temperature of 25 °C and 30 °C. The control group consisted of a 100 of adult volunteers.

RESULTS

The resting temperature of the middle fingers for a sitting participant was 28.6 ± 0.8 °C. The physiological change of this temperature during body position changes was 4.5 ± 1.1 °C and for most of the participants remained within the 26.5-31.5 °C range at 25 °C. For the toe, physiological skin temperature range was 25.5-33 °C. At 30 °C, these ranges were 27-33 °C for the fingers and 27-34 °C for the toes. On average, 2-3 min were needed for such temperature changes.

CONCLUSION

At normal room temperature, the SST of thermoneutral adolescents may vary within a range of approximately 5 °C only due to the blood redistribution in the body. This range is specific for each person due to individual peculiarities of the vasomotor activity. This normative range of SSTs should be taken into account during investigations of thermoregulation.

Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress

The differences in the degree of sympathetic nerve activity (SNA) over cutaneous blood vessels, although known to be more prominent in the periphery than the core vasculature, has not been thoroughly investigated quantitatively. Hence, two studies were carried out to investigate the differences in SNA between the periphery and the core during the cold pressor test (CPT) (right-hand immersion in ice water) and cold exposure (whole body exposed to cold air) using photoplethysmography (PPG). Two methods utilizing PPG, namely differential multi-site PTT measurements and low-frequency spectral analysis were explored for quantitative determination of SNA. Each study involved 12 healthy volunteers, and PPG signals were acquired from the right index finger (RIF), left index finger (LIF) (periphery) and the ear canal (core). During CPT, Pulse Transit Time (PTT) was measured to the respective locations and the mean percentage change in PTT during ice immersion at each location was used as an indicator for the extent of SNA. During cold exposure, the low-frequency spectral analysis was performed on the acquired raw PPGs to extract the power of the sympathetic [low-frequency (LF): 0.04–0.15 Hz] and parasympathetic components [high-frequency (HF): 0.15–0.4 Hz]. The ratio of LF/HF components was then used to quantify the differences in the influence of SNA on the peripheral and core circulation. PTT measured from the EC, and the LIF has dropped by 5 and 7%, respectively during ice immersion. The RIF PTT, on the other hand, has dropped significantly (P < 0.05) by 12%. During the cold exposure, the LF/HF power ratio at the finger has increased to 86.4 during the cold exposure from 19.2 at the baseline (statistically significant P = 0.002). While the ear canal LF/HF ratio has decreased to 1.38 during the cold exposure from 1.62 at baseline (P = 0.781). From these observations, it is evident that differential PTT measurements or low-frequency analysis can be used to quantify SNA. The results also demonstrate the effectiveness of the central auto-regulation during both short and long-term stress stimulus as compared to the periphery.

Onset Patterns and Course of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background: Epidemiologic studies of myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) have examined different aspects of this disease separately but few have explored them together. Objective: Describe ME/CFS onset and course in one United States-based cohort. Methods: One hundred and fifty subjects fitting Fukuda 1994 CFS criteria completed a detailed survey concerning the initial and subsequent stages of their illness. Descriptive statistics, graphs, and tables were used to illustrate prevalence and patterns of characteristics. Results: The most common peri-onset events reported by subjects were infection-related episodes (64%), stressful incidents (39%), and exposure to environmental toxins (20%). For 38% of subjects, more than 6 months elapsed from experiencing any initial symptom to developing the set of symptoms comprising their ME/CFS. Over time, the 12 most common symptoms persisted but declined in prevalence, with fatigue, unrefreshing sleep, exertion-related sickness, and flu-like symptoms declining the most (by 20-25%). Conversely, cognitive symptoms changed the least in prevalence, rising in symptom ranking. Pregnancy, menopause, and menstrual cycles exacerbated many women's symptoms. Fatigue-related function was not associated with duration of illness or age; during the worst periods of their illness, 48% of subjects could not engage in any productive activity. At the time of survey, 47% were unable to work and only 4% felt their condition was improving steadily with the majority (59%) describing a fluctuating course. Ninety-seven percent suffered from at least one other illness: anxiety (48%), depression (43%), fibromyalgia (39%), irritable bowel syndrome (38%), and migraine headaches (37%) were the most diagnosed conditions. Thirteen percent came from families where at least one other first-degree relative was also afflicted, rising to 27% when chronic fatigue of unclear etiology was included. Conclusions: This paper offers a broad epidemiologic overview of one ME/CFS cohort in the United States. While most of our findings are consistent with prior studies, we highlight underexamined aspects of this condition (e.g., the evolution of symptoms) and propose new interpretations of findings. Studying these aspects can offer insight and solutions to the diagnosis, etiology, pathophysiology, and treatment of this condition.

The physiology of impenetrable skin: Colossus of the X-Men

The X-Men are an ensemble of superheroes whose powers are associated with the X-Gene, a mutant genetic factor. The powers exhibited by each character differ and are dependent on how the X-Gene has modified their individual genomes. For instance, Wolverine possesses regenerative healing, Storm can control local weather systems, and Colossus can create an impenetrable "organic steel" layer around his body. Thanks to the establishment of the superhero genre in modern cinema, audiences are familiar with Colossus from films such as X-Men: Days of Future Past and Deadpool. While attaining this power might be attractive to many people, there are innumerate scientific obstacles to be overcome to replicate this "organic steel" layer. Due to its unique combination of high strength and flexibility, a graphene-based layer might be a more realistic material for Colossus' impenetrable skin and would also address a number of physiological issues associated with an "organic steel" layer. The actualization of this layer would depend on complex processes associated with protein folding, protein self-assembly, and changing the structure of his skin. In the classroom, Colossus can foster a multidisciplinary learning environment where concepts in physiology can overlap with topics in physics, engineering, and materials science. Just like other superheroes, Colossus can also be used to promote scientific content in outreach for the general public.

The Brain Mechanisms Underlying the Perception of Pungent Taste of Capsaicin and the Subsequent Autonomic Responses

In a human fMRI study, it has been demonstrated that tasting and ingesting capsaicin activate the ventral part of the middle and posterior short gyri (M/PSG) of the insula which is known as the primary gustatory area, suggesting that capsaicin is recognized as a taste. Tasting and digesting spicy foods containing capsaicin induce various physiological responses such as perspiration from face, salivation, and facilitation of cardiovascular activity, which are thought to be caused through viscero-visceral autonomic reflexes. However, this does not necessarily exclude the possibility of the involvement of higher-order sensory-motor integration between the M/PSG and anterior short gyrus (ASG) known as the autonomic region of the insula. To reveal a possible functional coordination between the M/PSG and ASG, we here addressed whether capsaicin increases neural activity in the ASG as well as the M/PSG using fMRI and a custom-made taste delivery system. Twenty subjects participated in this study, and three tastant solutions: capsaicin, NaCl, and artificial saliva (AS) were used. Group analyses with the regions activated by capsaicin revealed significant activations in the bilateral ASG and M/PSG. The fMRI blood oxygenation level-dependent (BOLD) signals in response to capsaicin stimulation were significantly higher in ASG than in M/PSG regardless of the side. Concomitantly, capsaicin increased the fingertip temperature significantly. Although there was no significant correlation between the fingertip temperatures and BOLD signals in the ASG or M/PSG when the contrast [Capsaicin-AS] or [Capsaicin-NaCl] was computed, a significant correlation was found in the bilateral ASG when the contrast [2 × Capsaicin-NaCl-AS] was computed. In contrast, there was a significant correlation in the hypothalamus regardless of the contrasts. Furthermore, there was a significant correlation between M/PSG and ASG. These results indicate that capsaicin increases neural activity in the ASG as well as the M/PSG, suggesting that the neural coordination between the two cortical areas may be involved in autonomic responses to tasting spicy foods as reflected in fingertip temperature increases.

Observing and understanding arterial and venous circulation differences in a physiology laboratory activity

The purpose of the present article is to describe three simple practical experiments that aim to observe and discuss the anatomic and physiological functions and differences between arteries and veins as well as the alterations observed in skin blood flow in different situations. For this activity, students were divided in small groups. In each group, a volunteer is recruited for each experiment. The experiments only require a sphygmomanometer, rubber bands, and a clock and allow students to develop a hypothesis to explain the different responses to the interruption of arterial and venous blood flow. At the end, students prepare a short report, and the results are discussed. This activity allows students to perceive the presence of physiology in their daily lives and helps them to understand the concepts related to the cardiovascular system and hemodynamics.

Recent advances in thermoregulation

Thermoregulation is the maintenance of a relatively constant core body temperature. Humans normally maintain a body temperature at 37°C, and maintenance of this relatively high temperature is critical to human survival. This concept is so important that control of thermoregulation is often the principal example cited when teaching physiological homeostasis. A basic understanding of the processes underpinning temperature regulation is necessary for all undergraduate students studying biology and biology-related disciplines, and a thorough understanding is necessary for those students in clinical training. Our aim in this review is to broadly present the thermoregulatory process taking into account current advances in this area. First, we summarize the basic concepts of thermoregulation and subsequently assess the physiological responses to heat and cold stress, including vasodilation and vasoconstriction, sweating, nonshivering thermogenesis, piloerection, shivering, and altered behavior. Current research is presented concerning the body's detection of thermal challenge, peripheral and central thermoregulatory control mechanisms, including brown adipose tissue in adult humans and temperature transduction by the relatively recently discovered transient receptor potential channels. Finally, we present an updated understanding of the neuroanatomic circuitry supporting thermoregulation.