Thermoregulatory System Research Articles

Comprehensive assessment of the state of the autonomic nervous system and features of thermoregulation in pregnant women

Comprehensive assessment of the state of the autonomic nervous system and features of thermoregulation in pregnant women

Evaluation of defatted krill meal as partial and total fishmeal replacement in diets for gilthead seabream (Sparus aurata) juveniles

Evaluation of defatted krill meal as partial and total fishmeal replacement in diets for gilthead seabream (Sparus aurata) juveniles

Identifying the neural signature of thermic comfort sensation: neuroergonomic evaluation of a new ventilating system integrated in car seat

Identifying the neural signature of thermic comfort sensation: neuroergonomic evaluation of a new ventilating system integrated in car seat

The Influence of Cold Atmospheric Air on the Environmental Health of Sportsman

On the basis of a systematic analysis of the scientific literature, it was found that the increased sensitivity of a modern human being to the negative effects of the cold natural environment is due to its passage from the shrouds of East Africa with characteristic high ambient temperatures, primarily atmospheric air. At the same time, in comparative terms, the extinct Neanderthal, with his Eurasian apprehension in the conditions of glacial periods, was on the contrary sufficiently well adapted to the cold environment. The subsequent adaptation of a modern human type at the genetic level with the formation of the main races (Caucasoid, Negroid, Mongoloid) could not sufficiently compensate for its insufficient resistance to the cold environment. According to the results of the research, the main ways of solving the problem of the negative influence of the cold natural environment on the ecological health of athletes were determined: the rationing of the order of sporting activities of athletes depending on the degree of low-temperature environment, diagnosing the athletes' hypersensitivity of the respiratory tract to cold atmospheric air, degree of tension of the processes of thermoregulation of the body. The conclusions are drawn according to which the prevention of the negative impact of extreme conditions of the cold environment (primarily cold atmospheric air) on the ecological health of athletes should be systemic, integrated. The system of preventive measures should include an early diagnosis of the development of airway hyperresponsiveness of athletes to the effects of cold atmospheric air, as well as an assessment of the degree of tension of the body's thermoregulatory system to the effect of cold. In the system of preventing the negative impact of the cold environment on the body of athletes engaged in winter sports in the open space, it is necessary to include regulation (normalization) of the temperature regime of cold atmospheric air when determining the possibility of holding sporting events. If necessary (the presence of hypersensitivity of the airways to the action of cold atmospheric air), it is advisable to use special means of protecting the respiratory tract of athletes from the negative influence of cold atmospheric air.

Development of thermoregulation system for athlete of spinal cord injury

Development of thermoregulation system for athlete of spinal cord injury

2-Deoxy-D-glucose, not mercaptoacetate, induces a reversible reduction of body temperature in male desert hamsters (Phodopus roborovskii)

The initiation of torpor is supposed to be related to the availability of metabolic fuels. Studies on metabolic fuel inhibition of glucose by using 2-deoxy-D-glucose (2DG) or fatty acid by mercaptoacetate (MA) in heterothermic mammals produced mixed outcomes. To examine the roles of availability of glucose and fatty acid in the initiation of torpor in desert hamsters (Phodopus roborovskii), we intraperitoneally administrated 2DG and MA to summer-acclimated male hamsters while body temperature (Tb), metabolic rate (MR) and respiratory quotient (RQ) were simultaneously recorded to monitor their thermoregulatory response. 2DG induced a reversible reduction of Tb in desert hamsters both at ambient temperature (Ta) of 23°C and 5°C. At Ta of 23°C, Tb, MR and RQ decreased in a dose-dependent manner with a large Tb-Ta differential (> 6.5°C) and a lowest Tb of 28.0°C which were comparable to those in fasted hamsters. At Ta of 5°C, 2DG-treated hamsters also decreased Tb to the same level as at Ta 23°C, but MR was significantly higher than that at Ta of 23°C at each dose, suggesting doses of 2DG directly affected the hypothalamic Tb set-point. Different from fasted hamsters which maintain normothermic at Ta of 5°C, 2DG-treated hamsters showed a substantial reduction of Tb at Ta 5°C, indicating an overwhelming effect on the thermoregulatory system regardless of Ta. Furthermore, the rapid decrease of Tb and outstretched body posture in 2DG-treated hamsters suggest that the effects of 2DG were not simply mimicking the torpor pathways but that other mechanisms are involved. Interestingly, MA failed to induce a torpor-like state in male desert hamsters. Our results suggest that availability of glucose rather than fatty acid plays an important role for initiation of torpor in desert hamsters.

Heat Loss Prevention Education Aids Nurses’ Knowledge in Prevention of Hypothermia in Newborns

ABSTRACTNewborns are at risk of developing hypothermia due to the instability of their thermoregulation systems and inability to adjust to changes in ambient temperature. This risk increases during hospitalization. Education is a strategy to improve nurses’ understanding of the prevention of hypothermia in newborns in the hospital. This study aimed to analyze the impact of education about preventing heat loss on nurses’ knowledge and behavior in preventing hypothermia in newborns. The study design was a quasi-experiment with one group pre-test–post-test and a total sample of 21 neonatal nurses who were selected using the consecutive sampling method. The results indicated that there was significant difference in nurses’ knowledge and behavior pre- and post-education intervention (p < .001; α = .05). This study suggests that education on prevention of heat loss is an effective strategy to promote nurses’ knowledge and behavior in preventing hypothermia.

Regulation of Brown Adipose Tissue Activity by Interoceptive CNS Pathways: The interaction between Brain and Periphery.

To maintain thermal homeostasis, specific thermogenic tissues are under the control of central thermoregulatory networks that regulate the body's response to thermal challenges. One of these mechanisms involves non-shivering thermogenesis in brown adipose tissue (BAT), which is activated in cold environments in order to defend the body against physical damage as a result of hypothermia. The objective of our study was to assess the interaction between CNS thermoregulatory pathways and sympathetic innervation in BAT during a cold exposure paradigm. Our results show that an innocuous whole-body cooling paradigm induces significant differences in fMRI BOLD signal at the location of the right anterior insula and the red nucleus/substantia nigra region, between lean subjects with high levels of sympathetic innervation in supraclavicular BAT (BAT+ group), and subjects with low levels of sympathetic innervation (BAT− group). Specifically, results indicate significantly larger fMRI BOLD signal changes between periods of cooling and warming of the skin in the BAT+ (as compared to BAT−) group at the location of the right anterior insula. In contrast, the BAT+ group showed significantly smaller fMRI BOLD signal changes in the midbrain between periods of skin cooling and warming. Our findings are consistent with a hierarchical thermoregulatory control system that involves the initiation of inhibitory signals from the right anterior insula toward midbrain areas that normally exert tonic inhibition on the medullary raphe, from where BAT is directly innervated. Our data suggests that exposure to cold elicits differential neuronal activity in interoceptive regulatory centers of subjects with high and low level of sympathetic innervation. As a result, the variability of cold-activated BAT mass observed in humans might be, in part, yoked to different sensitivities of interoceptive cortical brain areas to skin temperature changes.

Speciation in the Fe(III)-Cl(I)-H2O System at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C)

This article presents the results on speciation of ferric iron generated by the dissolution of chemical reagent hydromolysite (ferric chloride hexahydrate, FeCl3:6H2O) in water at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C). Experiments were performed with a thermoregulated system up to the equilibrium point, as manifested by solution pH. Solution samples were analyzed in terms of concentration, pH, and electrical conductivity. Measurements of density and refractive index were obtained at different temperatures and iron concentrations. A decrease of pH was observed with the increase in the amount of dissolved iron, indicating that ferric chloride is a strong electrolyte that reacts readily with water. Experimental results were modeled using the hydrogeochemical code PHREEQC in order to obtain solution speciation. Cations and neutral and anion complexes were simultaneously present in the system at the studied conditions according to model simulations, where dominant species included Cl−, FeCl2+, FeCl2 +, FeOHCl 2 0 , and H+. A decrease in the concentration of Cl− and Fe3+ ions took place with increasing temperature due to the association of Fe-Cl species. Standard equilibrium constants for the formation of FeOHCl 2 0 obtained in this study were log $$ K_{f}^{0} $$ = −0.8 ± 0.01 at 298.15 K (25 °C), −0.94 ± 0.02 at 313.15 K (40 °C), and −1.03 ± 0.01 at 333.15 K (60 °C).

QUALITY OF LIFE IN PATIENTS WITH CHRONIC PANCREATITIS AND RELATED ANEMIA

Вивчення якості життя (ЯЖ) у всьому світі є однією з актуальних проблем у медицині. Опитувальники є надійним і дійсним інструментом для вимірювання ЯЖ з точки зору пацієнта. Шкала часто використовуються з упевненістю у пацієнтів з хронічними захворюваннями, що потребують довготривалої терапії. У пацієнтів із хронічним панкреатитом (ХП) і супутньою анемією частіше зустрічаються супутні когнітивні порушення у молодих жінок, більший ризик летальності та госпіталізацій у дорослих і особливо у пацієнтів літнього віку, порушення терморегуляції, дисфункція імунної системи, шлунково-кишкові розлади, інфекція Helicobacter pylori, які ще більше знижують ЯЖ. Наше дослідження ЯЖ у пацієнтів із ХП і ХП із супутнім анемічним синдромом за допомогою опитувальників SF-36 і GSRS, продемонстрували значно нижчий рівень ЯЖ у пацієнтів із анемією. Це свідчить про об’єктивну обтяжувальну роль супутньої анемії на перебіг основного захворювання.

A Human Thermoregulation Simulator for Calibrating Water-Perfused Cooling Pad Systems for Therapeutic Hypothermia

The induction of a mild reduction in body core temperature has been demonstrated to provide neuroprotection for patients who have suffered a medical event resulting in ischemia to the brain or vital organs. Temperatures in the range of 32–34 °C provide the required level of protection and can be produced and maintained by diverse means for periods of days. Rewarming from hypothermia must be conducted slowly to avoid serious adverse consequences and usually is performed under control of the thermal therapeutic device based on a closed-loop feedback strategy based on the patient's core temperature. Given the sensitivity and criticality of this process, it is important that the device control system be able to interact with the human thermoregulation system, which itself is highly nonlinear. The therapeutic hypothermia device must be calibrated periodically to ensure that its performance is accurate and safe for the patient. In general, calibration processes are conducted with the hypothermia device operating on a passive thermal mass that behaves much differently than a living human. This project has developed and demonstrated an active human thermoregulation simulator (HTRS) that embodies major governing thermal functions such as central metabolism, tissue conduction, and convective transport between the core and the skin surface via the flow of blood and that replicates primary dimensions of the torso. When operated at physiological values for metabolism and cardiac output, the temperature gradients created across the body layers and the heat exchange with both an air environment and a clinical water-circulating cooling pad system match that which would occur in a living body. Approximately two-thirds of the heat flow between the core and surface is via convection rather than conduction, highlighting the importance of including the contribution of blood circulation to human thermoregulation in a device designed to calibrate the functioning of a therapeutic hypothermia system. The thermoregulation simulator functions as anticipated for a typical living patient during both body cooling and warming processes. This human thermoregulatory surrogate can be used to calibrate the thermal function of water-perfused cooling pads for a hypothermic temperature management system during both static and transient operation.

Therapeutic Equipment for Brain-Hyperthermia Using Convective Spray Cooling

A new type of therapeutic equipment is designed herein, using concepts of convective heat transfer and spray cooling, to treat patients suffering from brain-hyperthermia. The equipment is aimed to provide emergency treatment in order to prevent disability or possible mortality because thermoregulatory system of the patients fails to maintain a homeostasis. The equipment uses noncontact method of forced convection, applied uniformly at body exteriors. The heat exchanger is designed to contain four independent pipe-sections with orifice openings around the body. The cool-air, maintained within ASHRAE’s thermal comfort bounds, is sprayed through the orifices. Design improvements have been made on the basis of image analysis of the flow. The boundary layer (BL) analysis has also been performed over a specially designed mannequin with induced hyperthermia characteristics. The testing indicates a decay of ∼6 °C in 280 min with a time constant of 2 h. Comparative to existing techniques, in addition to being a noncontact approach, the equipment shows better thermoregulatory performance along with a flexibility to accommodate different body contours.

Testicular thermoregulation, scrotal surface temperature patterns and semen quality of water buffalo bulls reared in a tropical climate.

This study evaluated the capacity of thermoregulation and its consequences on the scrotal surface temperature patterns and semen quality of buffalo bulls raised in a wet tropical climate. Eleven water buffaloes were evaluated in the rainiest, in the transitional and in the less rainy season. Air temperature and humidity were consistently high, but the animals did not show thermal stress in any season. The scrotal temperature gradient of buffalo bulls using infrared thermography was described, and three parallel and decreasing thermal bands were characterised. Sperm quality (n=176 ejaculates) was maintained in normal parameters over the periods. Pearson's coefficients showed that sperm volume and progressive motility were negatively correlated with ocular globe, epididymal tail and minimum scrotal temperatures (p<.01). Sperm membrane integrity was negatively influenced by increases in epididymal tail and minimum scrotal temperatures (p<.01). Ocular globe temperature also showed positive correlation with rectal, spermatic cord, and epididymal tail temperatures (p<.01). Therefore, even under high temperature and humidity, the thermoregulatory system was effective in preventing heat stress and the normality of scrotal surface temperatures, spermatogenesis and sperm maturation were maintained.

APPLIED RESEARCH ASPECTS OF INTELLECTUAL PROCESS BASED ON THE CRITERIA OF RELIABILITY

Сontext. The complexity and ambiguity of the approach to the system of thermoregulation, makes it possible to meet most of the enduser requirements. Such problems are solved by creating a flexible software to manage temperature control systems. The main functional requirement for them is determined by the condition of thermal comfort: maintain the desired optimum temperature within the permissible limits of its rejection. Similar systems operate in conditions of uncertainty. In the course of such tasks proposed and considered a model based on fuzzy logic. Objective. Simulation of fuzzy process E-net for a sustainable mechanism to conflict situations. To improve system performance, you must evaluate the processes of device reliability. Method. A new method for the study of intellectual processes based on the criteria of reliability. This method is based on the expansion E-net that can reveal internal and external uncertainty in the system. Objective. Made meaningful analysis of the existing thermal control systems. The simulation of the adequacy of the system of processes, based on the consistency of properties, completeness, reliability, choice and alternatives simulated processes. Also analyzed the distributed heat supply facilities based on their clustering features of the density distribution. Conclusions. Obtained scientific and practical significance of results that minimize computational costs, improve the accuracy in decision-making, as well as more detailed further maintenance of complex industrial systems.

Thermophysiological response of Newton manikin equipped with power-assisted filtering device incorporating a full-face mask in hot environment

One of the most common reasons inducing discomfort in wearing a respirator is an unpleasant local thermal perception. In this study, the effect of a power-assisted filtering device incorporating a full-face mask on the thermophysiological response was investigated by performing tests on a Newton manikin in a climatic chamber, where hot conditions were simulated setting the ambient temperature at 34 °C and the relative humidity at 32%. Two different levels of metabolic rate (1 MET and 3 MET) were considered. Results show that the variation of metabolic rate plays an important role in the heat exchanges with the environment causing different values of the local and global temperatures. At 1 MET the manikin is in thermal balance with the external environment with or without respirator. At 3 MET although the thermoregulation system is very stressed (the rectal temperature Tre increases continuously with or without respirator), the effect of the respirator produces a small decrease of the local and global temperatures and also of the amount of sweat generated by active thermoregulation Swa (reaching its maximum value of 30 g/min when the respirator is not worn). Furthermore, a little amelioration of the face and body sensation and comfort was observed. In any case, wearing the respirator seems not to provide additional thermal load.

Numerical Investigation of Ventilation and Human Thermoregulation for Predicting Thermal Comfort of a Rider Wearing Ventilated Helmet

Effectiveness of ventilated helmets in providing thermal comfort to a motorcycle rider is studied. Computational fluid dynamics (CFD) simulations of human thermoregulation system and the air flow in the air gap of a full-face motorcycle helmet are carried out. The thermal comfort of a rider is predicted using apparent temperature (AT) and wet-bulb global temperature (WBGT) heat indices. The effect of an increase in ambient temperature and relative humidity (RH) of air on the air flow and temperature in the region above the head is studied to predict the thermal comfort of the rider wearing full-face helmets. The effect of increasing the air gap between the head and the helmet is also studied. The results are then compared with the conditions when the rider is not wearing helmet. It is observed that the ventilated helmet is effective in providing thermal comfort to the rider only if the ambient air temperature is less than normal body temperature. For air temperature higher than the body temperature, vents do not provide any cooling to the head and the nonventilated helmet is more comfortable. Furthermore, CFD simulations are performed to investigate the effect of increase in RH in the ambient air on the thermal comfort of the rider. The increase in RH of air from 50% to 90% at a fixed ambient air temperature leads to an increase in AT and WBGT, indicating reduced thermal comfort of the rider.

Influence of temperature and growth selection on turkey pectoralis major muscle satellite cell adipogenic gene expression and lipid accumulation

Immature poults have an inefficient thermoregulatory system, and therefore extreme ambient temperatures can impact their internal body temperature. Satellite cells, the only posthatch myonuclei source, are multipotential stem cells and sensitive to temperature. Selection for faster-growing, high-yielding birds has altered satellite-cell properties. The objective of the current study was to determine how temperature affects adipogenic properties of satellite cells isolated from the pectoralis major (p. major) muscle of Randombred Control line (RBC2) and F line turkeys selected only for increased 16-wk body weight from the RBC2 line. Satellite cells were cultured at 2°C incremental temperatures between 33 and 43°C and compared to cells cultured at the control temperature of 38°C to ascertain temperature effects on lipid accumulation and expression of adipogenic genes: CCAAT/enhancer-binding protein-β (C/EBPβ), peroxisome proliferator-activated receptor-γ (PPARγ), and stearoyl-CoA desaturase (SCD). During proliferation, the amount of quantifiable lipid in both F and RBC2 satellite cells increased at temperatures above 38°C (P < 0.01) and decreased at temperatures below 38°C (P < 0.01). Above 38°C, RBC2 satellite cells had more lipid (P = 0.02) compared to the F line, whereas there were few differences between lines below 38°C. At 72 h of proliferation, expression of C/EBPβ, PPARγ, and SCD decreased (P ≤ 0.02) as temperatures increased from 33 to 43°C in both cell lines. During differentiation expression of C/EBPβ increased (P < 0.01) as temperatures increased from 33 to 43°C in both cell lines. In F line satellite cells, PPARγ expression decreased (P < 0.01) with increasing temperatures during differentiation, whereas there was no linear trend in RBC2 cells. During differentiation expression of SCD increased as temperatures increased (P < 0.01) in RBC2 cells, and there was no linear trend within the F line. Results from the current study suggest that environmental temperature can affect p. major satellite cellular fate; however, selection for increased body weight had little impact on these cellular responses.

Temperature-Responsive Ionic Liquids: Fundamental Behaviors and Catalytic Applications.

Temperature-responsive ionic liquids (ILs), their fundanmental behaviors, and catalytic applications were introduced, especially the concepts of upper critical solution temperature (UCST) and lower critical solution temperature (LCST). It is described that, during a catalytic reaction, they form a homogeneous mixture with the reactants and products at reaction temperature but separate from them afterward at ambient conditions. It is shown that this behavior offers an effective alternative approach to overcome gas/liquid-solid interface mass transfer limitations in many catalytic transformations. It should be noted that IL-based thermomorphic systems are rarely elaborated until now, especially in the field of catalytic applications. The aim of this article is to provide a comprehensive review about thermomorphic mixtures of an IL with H2O and/or organic compounds. Special focus is laid on their temperature dependence concerning UCST and LCST behavior, including systems with conventional ILs, metal-containing ILs, polymerized ILs, as well as the thermomorphic behavior induced via host-guest complexation. A wide range of applications using thermoregulated IL systems in chemical catalytic reactions as well as enzymatic catalysis were also demonstrated in detail. The conclusion is drawn that, due to their highly attractive behavior, thermoregulated ILs have already and will find more applications, not only in catalysis but also in other areas.

Three-dimensional finite element model to study temperature distribution in peripheral layers of human limbs immediately after physical exercise

The physical exercise imposes challenges on the human thermoregulatory system, as heat exchange between the body and environment is substantially impaired, which can lead to decrease in performance and increased risk of heat illness. In view of above a three-dimensional finite element model is proposed to study the effect of different intensities of physical exercise on temperature distribution in peripheral regions of human limbs under moderate climatic conditions. Human limb is assumed to have a cylindrical cross-section. The peripheral region of the human limb is divided into three natural components, namely epidermis, dermis and subdermal tissues. The model incorporates the effect of important physiological parameters like blood mass flow rate, metabolic heat generation, and thermal conductivity of the tissues. Appropriate boundary conditions have been framed based on the physical conditions of the problem. The model is transformed into the discretized variational form and finite element method (FEM) has been employed to obtain the solution. The numerical results have been used to obtain the temperature profiles in the region immediately after exercise for an unsteady state case. The thermal information generated from the model can be useful for developing protocols for improving performance of sportsmen, military persons and labor-intensive workers.

Impaired sweating responses to a passive whole body heat stress in individuals with multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS), disrupting autonomic function. The aim of this study was to test the hypothesis that individuals with MS have blunted control of thermoregulatory reflex increases in sweat rate (SR) and cutaneous vasodilation compared with controls during a passive whole body heat stress (WBH). Eighteen individuals with relapsing-remitting MS and 18 healthy controls (Con) participated in the study. Core temperature (Tcore), skin temperature, heart rate, arterial blood pressure (10-min intervals), skin blood flow (laser-Doppler flux, LDF), and SR were continuously measured during normothermic baseline (34°C water perfusing a tube-lined suit) and WBH (increased Tcore 0.8°C via 48°C water perfusing the suit). Following WBH, local heaters were warmed to 42°C, inducing peak cutaneous vasodilation at the site of LDF collection. Cutaneous vascular conductance (CVC) was calculated as the ratio of LDF to mean arterial pressure and expressed as a percentage of peak achieved during local heating. Individuals with MS had attenuated SR responses to WBH (ΔSR from baseline: Con, 0.65 ± 0.27; MS, 0.42 ± 0.17 mg·cm-2·min-1, P = 0.003), whereas Δ%CVC42C from baseline was similar between groups (Con, 42 ± 16%; MS, 38 ± 12%, P = 0.39). SR responses were blunted as a function of Tcore in MS (interaction: group × Tcore, P = 0.03), of which differences were evident at ΔTcore 0.7°C and 0.8°C (P < 0.05). No interaction was observed in Δ%CVC42C Taken together, the findings show MS blunts sweating responses, whereas control of the cutaneous vasculature is preserved, in response to WBH.NEW & NOTEWORTHY This study is the first to assess the reflex control of the thermoregulatory system in individuals living with multiple sclerosis (MS). The novel findings are twofold. First, attenuated increases in sweat rate in subjects with MS compared with healthy controls were observed in response to a moderate increase (0.8°C) in core temperature via passive whole body heat stress. Second, it appears the reflex control of the cutaneous vasculature is preserved in MS.