Maintenance Of Normal Body Temperature Research Articles

Regulation of Neural Functions byBrain Temperature and Thermo-TRP Channels.

Body temperature is an important determinant in regulating the activities of animals. In humans, a mild 0.5°C hyperthermia can cause headaches, demonstrating that the maintenance of normal body temperature is a key for our health. In a more extreme example, accidental acute hypothermia can lead to severe shivering, loss of consciousness, or death, although the details of these mechanisms are poorly understood. We previously found that the TRPV4 ion channel is constitutively activated by normal body temperature. The activation threshold of TRPV4 is >34°C in the brain, which enables TRPV4 to convert thermal information into cellular signaling. Here we review the data that describe how the deletion of TRPV4 evokes abnormal behavior in mice. These studies demonstrate that the maintenance of body temperature and the sensory system for detecting body temperature, such as via TRPV4, are critical components for normal cellular function. Moreover, abnormal TRPV4 activation exacerbates cell death, epilepsy, stroke, or brain edema. Notably, TRPV4 can detect mechanical stimuli and contributes to various neural functions similar to the mechanosensitive characteristics of TRPV2. In this review, I summarize the findings related to TRPV2/TRPV4 and neural functions.

Perioperative Hypothermia Is Associated With Increased 30-Day Mortality in Hip Fracture Patients in the United Kingdom: Α Systematic Review and Meta-analysis.

To undertake a systematic review and meta-analysis to determine the relationship between perioperative hypothermia and mortality after surgery for hip fracture. A systematic literature search of Medline, EMBASE, CINAHL, and Cochrane CENTRAL databases was performed using the Cochrane methodology for systematic reviews with no publication year limit. Only studies available in the English language were included. Predetermined inclusion criteria were patients of any age with a hip fracture, exposure was their body temperature and outcome was mortality rate. Any comparative study design was eligible. The quality of selected studies was assessed according to each study design with the Methodological Index for Non-Randomised Studies (MINORS) used for all the retrospective comparative studies. The GRADE approach was used to assess the quality of evidence. A meta-analysis was conducted using a random-effects model. The literature search identified 1016 records. After removing duplicates and those not meeting inclusion criteria, 3 studies measuring 30-day mortality were included. All included studies were carried out in the United Kingdom. The mortality rate was higher in the hypothermic groups as compared with the normothermic group in all the studies, with the difference being significant in 2 of the studies (P < 0.0001). The meta-analysis showed that low body temperature was associated with an increased mortality risk (estimated odds ratio: 2.660; 95% confidence interval: 1.948-3.632; P < 0.001) in patients undergoing surgery for hip fracture. This study shows that low body temperature in hip fracture patients is associated with an increased 30-day mortality risk in the United Kingdom. Randomized control trials are required to determine whether the association between perioperative hypothermia in hip fracture patients and mortality is causal. Nevertheless, based on this analysis, we urge the maintenance of normal body temperature in the perioperative period to be included in national hip fracture guidelines. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Evidence-Based Approaches in Children with Hypothermia

The normal level of functioning of various metabolic processes in our body depends on normal body temperature. It is very important to maintain the patient's normal body temperature before, during, and after surgery to prevent possible complications. The occurrence of postoperative hypothermia is higher than hyperthermia. Pediatric hypothermia is a condition that needs to beprevented. Today, the use of various methods helps to prevent hypothermia; and guidelines exist for the prevention and management of hypothermia, supported by research that makes this process more reliable. With this mini-review, we aim to create a common multidisciplinary approach to prevent hypothermia. This study is about the current views addressing the maintenance of normal body temperature and discusses the risk factors predisposing to hypothermia and the goals of evidence-based hypothermia management in pediatric patients.

The Comparison between Different types of Cold Fluid Ingestion towards Endurance Exercise in Hot and Humid Condition

The rise in body core temperature associated with continuous exercise in hot and humid environments is known to possess a particularly stressful challenge to the maintenance of normal body temperature and fluid homeostasis. Recent evidence has shown that internal cooling methods, such as drinking cold fluids, are able to lower core temperature and enhance endurance performance in the heat. Pre-cooling (before exercise) and per-cooling (during exercise) methods were use, as ingesting cold fluids is easily implemented on site and provides additional benefit of hydration for athletes. Therefore, this study examines the effectiveness of pre-cooling and per-cooling methods on endurance exercise towards heart rate, rectal temperature, sweat rate, and power output of athletes ingesting different types of cold fluids. 3 female high-performance cyclists were asked to complete a 30km time trial on a cycle ergometer. The familiarisation and experimental sessions were identical, however application of fluid ingestion at 4-5°C before and during exercise differs (plain water = PW, Guava juice = GJ, isotonic drink = ID). Fluid is ingested every 15 minutes during the exercise sessions. As different athletes possess different work intensities, results showed that there is no significant difference on the effects of different types of cold fluid ingestion towards thermoregulation of the body as each fluid succeeded in enhancing athletes’ performance. Therefore, it is suggested that the consumption of any types of fluid at cold temperature could help in body thermoregulation as well as enhancing continuous exercise performance.

Exploring the potential use of whole plant therapies, &lt;i&gt;Cymbopogon citratus&lt;/i&gt;, as alternatives/complements to antimalarial pharmaceuticals: A preliminary report

Parasite resistance, toxicity/adverse reactions, adulteration as well as limited affordability and accessibity to common antimalarial drugs necessitate continuous search for better options. We evaluated the antimalarial potential of Whole Plant (WP) Cymbopo gencitratus (Lemon grass)as well as its combination with the old antimalarial chloroquine in a rodent malaria model, Plamodium chabaudi CR. WP C. citratus exhibited delayed but significant (p<0.001) and sustained activity against established infection compared with controls and chloroquine respectively. Significant increase in heamoglobin concentration (p<0.01) and maintenance of normal body temperature (p<0.01) in the WP treatment group coincided with the period of antimalarial activity of the Whole Plant. Contrary to our expectations but interestingly, the WP C. citratus and chloroquine combination did not yield significantanti malarial activity. These preliminary results suggest that WP C. citrates may be more effective as a prophylactic agent with useful implications for intermittent preventive treatments and requires further investigation. The outcome of the WP/Chloroquine combination on the other hand suggests the induction of a redox environment that may have reduced the potency of both treatments when combined. This however requires further investigation as it may have some implications for antimalarial treatment protocols, origins of antimalarial resistance and future antimalarial options in endemic areas.Keywords: Cymbopo gencitratus; prophylactic agent; safe herb.

Patients' Opinions of OR Nurses and Environments in the Postoperative Period

To determine patients' opinions of operating room (OR) nurses and environments in the postoperative period. A descriptive study. The data were collected by using researcher developed forms that defined patients' opinions of OR nurses and environments and were given to the patients on the first postoperative day. The final sample consisted of a total of 208 patients who underwent surgery with regional anesthesia. Percentage measurements were used in the assessment of data. The majority (69.3%) of nurses did not introduce themselves to their patients and 61.3% failed to introduce the OR environments to their patients. Patients explored their (ORs) in the range of 62% and 90% and considered these locations to be calm and reliable environments where their needs were met and their communications with the staff were positive. The rate of patients who felt that their ORs were not cold was 35.3%. In this study, most patients were not aware that OR nursing played an important role in a postive patient perception of the OR. Most OR nurses did not introduce themselves to patients while providing nursing care, and patients were not aware of who provided this service to them. In light of these findings, it is recommended that nurses introduce themselves to patients in the OR when beginning care of the patient. Moreover, special effort should be made regarding maintenance of normal body temperature of patients in the OR.

Anesthesia, Microcirculation, and Wound Repair in Aging

Age-related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types, and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control, and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation of a combination of effects on cardiac output, arterial pressure, and local microvascular changes. The authors examined the role of anesthetic management in optimizing the microcirculation and potentially improving postoperative wound repair in older persons.

Anesthesia, Microcirculation, and Wound Repair in Aging

Age-related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types, and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control, and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation of a combination of effects on cardiac output, arterial pressure, and local microvascular changes. The authors examined the role of anesthetic management in optimizing the microcirculation and potentially improving postoperative wound repair in older persons.

Adipose Acyl-CoA Synthetase-1 Directs Fatty Acids toward β-Oxidation and Is Required for Cold Thermogenesis

Long-chain acyl-CoA synthetase-1 (ACSL1) contributes 80% of total ACSL activity in adipose tissue and was believed to be essential for the synthesis of triacylglycerol. We predicted that an adipose-specific knockout of ACSL1 (Acsl1(A-/-)) would be lipodystrophic, but compared to controls, Acsl1(A-/-) mice had 30% greater fat mass when fed a low-fat diet and gained weight normally when fed a high-fat diet. Acsl1(A-/-) adipocytes incorporated [(14)C]oleate into glycerolipids normally, but fatty acid (FA) oxidation rates were 50%-90% lower than in control adipocytes and mitochondria. Acsl1(A-/-) mice were markedly cold intolerant, and beta(3)-adrenergic agonists did not increase oxygen consumption, despite normal adrenergic signaling in brown adipose tissue. The reduced adipose FA oxidation and marked cold intolerance of Acsl1(A-/-) mice indicate that normal activation of FA for oxidation in adipose tissue in vivo requires ACSL1. Thus, ACSL1 has a specific function in directing the metabolic partitioning of FAs toward beta-oxidation in adipocytes.

Synergism of isothermal regimen and sodium succinate in experimental therapy of barbiturate coma

In rats with experimental thiopental coma rectal temperature decreased by 9.4 degrees C, oxygen consumption 5-fold, and arteriovenous Po(2)gradient decreased 2-fold within 3 h; CO(2)accumulated in the blood and mixed type acidosis developed. Administration of sodium succinate under these conditions increased arteriovenous Po(2)gradient and reduced manifestations of metabolic acidosis. Maintenance of normal body temperature (warming) corrected primarily manifestations of respiratory acidosis. Each therapeutic agent reduced inhibition of O(2)consumption by 1/4; animal survival tended to increase from 42 to 50%. Combined use of these treatments potentiated the antiacidotic effect and increased survival to 92%. The authors conclude that hypothermia inhibits the therapeutic effect of succinate in barbiturate coma.

Perioperative cardiac risk reduction: doing it right.

arious interventions to reduce the risk of cardiac complications during surgery have been proposed. This article evaluates the evidence for these preventive approaches, examines methods of incorporating new and conflicting evidence into a coherent clinical approach, and reviews systems for successfully implementing evidence-based interventions in the hospital. ■ APPROACHES FOR PREVENTING CARDIAC COMPLICATIONS With revascularization reserved as a preventive measure for those patients at extremely high risk of cardiac complications, other less invasive preventive approaches should be considered. Maintenance of normothermia One preventive approach is maintenance of normal body temperature. In a randomized, controlled clinical study of 300 patients with or at high risk for coronary disease who underwent major abdominal or vascular surgery, supplemental warming care was associated with a significant (P = .02) reduction in perioperative morbid cardiac events compared with routine thermal care. 1 The risk of supplemental warming is low and the potential reward is high; in addition to the reduction in cardiac complications, patients randomized to normothermia in this study had a lower rate of surgicalsite infections, less nausea, and better pain control. Calcium channel blocker therapy A recent meta-analysis 2 demonstrated a significant reduction in adverse coronary endpoints with the use of calcium channel blockers, compared with placebo, as preventive therapy in patients undergoing various types of surgery. This reduction in the risk of events, however, was driven entirely by a significant reduction in the incidences of ischemia and supraventricular tachycardia, with no effect of calcium channel blockers on perioperative myocardial infarction (MI) or death. The largest reductions in risk with calcium channel blockers occurred in patients undergoing thoracic surgery. In most of the studies in which a favorable effect of calcium channel blockers was observed, patients were on concomitant beta-blockade that was not adequately controlled for, which obscures interpretation of the meta-analysis. For these reasons, calcium channel blockers should not be considered firstline therapy as a preventive strategy.

Succinate and artificial maintenance of normal body temperature synergistically correct lethal disorders in thiopental coma rat

Under modeling of thiopental coma influence of sodium succinate and (or) external warming for the support of normal body temperature (isothermal regimen) on the gas exchange, blood gas content, acid–base status and survival rate was studied in rats. In the absence of therapy hypothermia was developed (−9.4 °C), O 2 consumption decreased by a factor 5, oxygenation of arterial blood ( pO 2) did not change while that of venous blood increased, wherewith arteriovenous oxygen tension gradient decreased by half. Blood tension of carbon dioxide ( pCO 2) increased twice, respiratory and metabolic acidosis was developed. Survival rate under absence of a therapy was 42%, with isolated use of isothermal regimen or succinate therapy alike—50%; with their use in combination drastically increased up to 92%. Succinate increased arteriovenous gradient of pO 2, decreased deficit of buffer bases, increased bicarbonate concentration. At isothermal regimen accumulation of CO 2 in the blood was diminished, its excretion was increased, pH of blood approached normal values. Combined use of both therapy agents increased O 2 consumption and potentiated their positive influence on acid–base status. The implication is that hypothermia restrains effect of succinate in barbiturate coma; prevention of hypothermia in combination with succinate administration is highly effective method of experimental therapy of barbiturate intoxication.

Transgenic Sickle Mice Are Markedly Sensitive to Renal Ischemia-Reperfusion Injury

Ischemic injury is invoked as a mechanism contributing to end-organ damage and other complications of sickle cell disease (SCD). However, the intrinsic sensitivity of tissues in SCD to ischemic insults has never been addressed. We examined the effect of renal ischemia in a transgenic mouse expressing human sickle hemoglobin. Twenty-four hours after bilateral, total renal artery occlusion for 15 minutes, transgenic sickle mice exhibited worse renal function and more marked histological injury. With bilateral renal ischemia of greater duration (22.5 minutes), and after 6 hours, transgenic sickle mice exhibited massive vascular congestion, sickling of red blood cells, more marked histological injury in the kidney, and more prominent congestion in the capillary beds in the lungs and heart. Additionally, serum amyloid P-component, the murine homologue of C-reactive protein, was markedly increased in transgenic sickle mice as compared to wild-type mice. Twenty-four hours after bilateral renal ischemia for 22.5 minutes, transgenic sickle mice exhibited 28% mortality, with no mortality observed in any other group. With bilateral renal ischemia of short or long duration, renal expression of caspase-3 was most prominent in transgenic sickle mice subjected to ischemia. Thus, renal ischemia in this murine model induces more severe renal injury and extrarenal complications. We conclude that tissues in SCD exhibit heightened vascular congestion and sensitivity to ischemia and that clinically apparent or silent episodes of ischemia may contribute to the complications of SCD.

The Evolution of Neonatology

In 1960, the terms "neonatology" and "neonatologist" were introduced. Thereafter, an increasing number of pediatricians devoted themselves to full-time neonatology. In 1975, the first examination of the Sub-Board of Neonatal-Perinatal Medicine of the American Board of Pediatrics and the first meeting of the Perinatal Section of the American Academy of Pediatrics were held. One of the most important factors that improved the care of the neonate was the miniaturization of blood samples needed to determine blood gases, serum electrolytes, glucose, calcium, bilirubin, and other biochemical measurements. Another factor was the ability to provide nutrition intravenously, and the third was the maintenance of normal body temperature. The management of respiratory distress syndrome improved with i.v. glucose and correction of metabolic acidosis, followed by assisted ventilation, continuous positive airway pressure, antenatal corticosteroid administration, and the introduction of exogenous surfactant. Pharmacologic manipulation of the ductus arteriosus, support of blood pressure, echocardiography, and changes in the management of persistent pulmonary hypertension, including the use of nitric oxide and extracorporeal membrane oxygenation, all have influenced the cardiopulmonary management of the neonate. Regionalization of neonatal care; changes in parent-infant interaction; and technological changes such as phototherapy, oxygen saturation monitors, and brain imaging techniques are among the important advances reviewed in this report. Most remarkable, a 1-kg infant who was born in 1960 had a mortality risk of 95% but had a 95% probability of survival by 2000. However, errors in neonatology are acknowledged, and potential directions for the future are explored.

Barbara Cannon's data on the UCP1-ablated mice: "non-cannonical" point of view.

The data of Cannon and co-workers on UCP1-ablated mice are interpreted assuming that UCP2 and UCP3 are involved in thermoregulation as fatty acid-dependent uncouplers although they are not sufficient, in the absence of UCP1, for long term maintenance of normal body temperature of mice after sudden and strong decrease in the ambient temperature. I would like to suggest that in brown fat of control mice, UCP1 is present in an amount higher than UCP2 and 3 and, therefore, is able to cause (a) some fatty acid-mediated decrease in proton motive force in resting state and, hence, (b) oxidation of CoQH2 to CoQ which is shown by Klingenberg and coworkers to be cofactor for UCPs. This results in strong uncoupling and thermogenesis mediated by UCP1, 2 and 3. In the UCP1-ablated mice, activity of UCP2 and 3 appears to be insufficient to induce CoQH2 oxidation in resting brown fat mitochondria, which results in hypothermia.

Reduced febrile responses to pyrogens after lesions of the hypothalamic paraventricular nucleus

The hypothalamic paraventricular nucleus (PVN) is recognized as a major site of autonomic control, but the role of this nucleus in thermoregulation is unclear. Therefore the role of the PVN in the febrile response and in the maintenance of normal body temperature was investigated. Conscious, unrestrained rats with chronic lesions of the PVN received intracerebroventricular injections of several doses of prostaglandin (PG) E2 or intraperitoneal applications of Escherichia coli lipopolysaccharide. The body temperatures of both lesioned and sham-operated animals, monitored via radio telemetry, were compared. Intracerebroventricular PGE2 at doses of 10, 25, and 50 ng caused dose-dependent fevers in both PVN-lesioned and sham-operated animals, which at lower doses were smaller in the lesioned animals than in the sham-operated animals. Intraperitoneal lipopolysaccharide application, 50 micrograms/kg body wt, evoked a significantly lower febrile response in PVN-lesioned animals than in controls. The body temperature of PVN-lesioned animals and controls showed no difference during 300 min of exposure to heat (32 degrees C) or cold (7 degrees C). These results suggest that the PVN contributes to the complex regulation of temperature during the febrile response but not during the maintenance of normal body temperature.

Effects of successive carbon monoxide exposures on delayed neuronal death in mice under the maintenance of normal body temperature

The 3 time carbon monoxide (CO) exposures potentiated the delayed neuronal death (DND) in comparison with that induced by single CO exposure. Deterioration of DND induced by CO exposures was observed when normal body temperature was maintained during the exposures, since CO exposure fell the body temperature to about 34 degrees C. Pretreatment with noncompetitive NMDA receptor antagonist, MK-801 (30 nmol/mouse), ameliorated DND induced by successive CO exposures under the maintenance of normal body temperature. These results suggest that the mice exposed successively to CO under the maintenance of normal body temperature is a useful hypoxic model.

Endorphin-induced hyperthermia: characterization of the exogenously and endogenously induced effects.

Endorphins-like opiates-were found to increase temperature at very low doses and to decrease temperature at high doses. Not only the decreasing, but also the increasing effect on temperature, seems to be mediated through opiate receptors, since it proved to be antagonizable by naloxone and to be diminished in morphine-tolerant and-dependent animals. Like opiate-induced hyperthermia, both the pharmacological as well as the supposedly physiological increase in temperature induced by endorphins were strongly diminished in restrained animals. Hyperthermia induced by pyrogens, however, was not antagonizable by either naloxone or restraining of the animals. Maintenance of normal body temperature in animals being exposed to acute cold could not be disturbed by administration of naloxone. As a whole, such findings support the suggestion derived from our previous observation that physiologically induced naloxone-antagonizable hyperthermia may be a sensitive measure for endorphin release. However, endorphins although being potent hyperthermic modulators of temperature, do not seem to be directly involved in the central regulation of temperature. Instead, the physiologically induced increase in temperature by endorphins seems to represent some epiphenomenon of physiological events primarily initiated for physiological requirements other than the support of thermostability.

Plumage and Ecology of Cormorants

The paper draws on data attending the etho-ecology of four species of cormorants (Phalacrocoracidae) in support of an hypothesis for the adaptive significance of the predominantly dark plumage of these birds. It is suggested that a dark plumage, primarily by being most receptive to solar radiation, assists cormorants in supplementing metabolic heat for maintenance of normal body temperature. In those cormorants which have white extending over ventral and frontal aspects of the body, it is suggested that this is an adaptation to the feeding situation and that it promotes 'hunting camouflage' through countershading.

The importance of changes in body temperature in paediatric surgery and anaesthesia.

An understanding of the maintenance of normal body temperature, and the manner in which surgery, anaesthesia, and related procedures may disturb thermoregulation, is of considerable importance in paediatric anaesthesia. The subject of accidental hypothermia, with particular reference to the newborn infant, is reviewed; and hyperpyrexia is briefly discussed.