Seasonal acclimatization of non-shivering thermogenesis in common spiny mice (Acomys cahirinus) from different habitats

We compared non-shivering thermogenesis between two adjacent populations of freshly captured common spiny mice (Acomys cahirinus) during both winter and summer. Mice were captured from north- and south-facing slopes (NFS and SFS) of the same valley that represent 'Mediterranean' and 'Desert' habitats, respectively. Oxygen consumption and body temperature responses to an injection of exogenous noradrenaline (NA) were higher during the winter than during the summer. in addition, SFS mice had a lower body temperature response to NA during the summer than the other groups of mice. This suggests that heat dissipation is likely to have been greatest in SFS mice during the summer. Overall this study shows that seasonal acclimatization of NST mechanisms is an important trait for small mammals that inhabit the Mediterranean ecosystem. Differences in physiological capabilities can occur temporally within populations across seasons, and spatially between populations that are only a short distance (200-500 m) apart.

Non-shivering thermogenesis in common spiny mice Acomys cahirinus from adjacent habitats: response to seasonal acclimatization and salinity acclimation

1. We compared resting metabolic rate (RMR) and non-shivering thermogenesis (NST) values between founder and F1-populations of winter-acclimatized Acomys cahirinus that originated from north- and south-facing slopes (NFS and SFS) of the same valley, representing mesic and xeric habitats. 2. NST was measured by the increase in oxygen consumption (VO2) and body temperature (T-b) after a noradrenaline (NA) injection (VO2 NA, TbNA). 3. Body mass and TbNA values were higher in SFS F1-mice, while RMR and VO2 NA values were higher in NFS F1-mice. Differences were not apparent in founders. 4. Results are consistent with NFS and SFS mice being considered as

Comparative non-shivering thermogenesis in adjacent populations of the common spiny mouse (Acomys cahirinus) from opposite slopes: the effects of increasing salinity

We compared non-shivering thermogenesis between two adjacent populations of the common spiny mouse Acomys cahirinus from different habitats, in relation to increasing salinity. Individuals were captured from the north- and south-facing slopes of the same valley, that represent

Hibernation and non-shivering thermogenesis in the Hottentot golden mole (Amblysomus hottentottus longiceps)

Although heterothermy (hibernation and torpor) is a common feature among mammals, there is debate over whether it is a derived or ancestral trait relative to endothermic homeothermy. Determination of the physiological characteristics of primitive mammals is central to understanding the evolution of endothermy. Moreover, evaluation of physiological mechanisms responsible for endothermic heat production [e.g. non-shivering thermogenesis (NST)] is key to understanding how early mammals responded to historical climate changes and colonised different geographical regions. Here we investigated the capacity for NST and heterothermy in the Hottentot golden mole, a basal eutherian mammal. NST was measured as the metabolic response to injections of noradrenalin and heterothermy by recording body temperature in free-ranging animals. We found that hibernation and torpor occurred and that the seasonal phenotypic adjustment of NST capacity was similar to that found in other placental mammals. Using phylogenetically independent contrasts, we compared measured values of NST with those obtained from the literature. This showed that all variation in NST was accounted for by differences in phylogeny and not zoogeography. These findings lend support to the observation that NST and heterothermy occur in the Afrotheria, the basal placental mammalian clade. Furthermore, this work suggests that heterothermy, rather than homeothermy is a plesiomorphic trait in mammals and supports the notion that NST mechanisms are phylogenetically ancient.

The Chihuahua sustainability practice: lots of shivering but no real action. Practical sustainability acceptance is low in German and New Zealand firms

Purpose – This paper aims to describe the extent to which corporate organizations in Germany and in New Zealand have included sustainability practices as part of their strategic planning process.

Design/methodology/approach – Current literature is reviewed to make a case for sustainability to be a driver behind corporate decision making and long-term performance. The results of surveys of several hundred firms in both Germany and New Zealand, countries with a publicly stated commitment to sustainability, are reviewed to compare the adoption rates of sustainability practices.

Findings – There is a significant difference between what firms do and what their managers think is important. Managers largely consider sustainability practices an important factor for their future careers, while firms to a large extent do not include sustainability as part of their strategic or operational planning process.

Research limitations/implications – The International Sustainability Acceptance Measurement (ISAM) collects data in several countries through local-language versions of the same online survey tool (www.worldreply.com). The findings in this report are specific only to New Zealand and Germany.

Practical implications – The paper points academics, corporate executives and sustainability fanatics to an alarming inconsistency between what is publicly reported as commitment to sustainability and what is practically achieved.

Originality/value – This paper adds value to the discussion of how sustainability practices have migrated into the operation of firms.

Ondansetron does not reduce the shivering threshold in healthy volunteers

BACKGROUND: Ondansetron, a serotonin-3 receptor antagonist, reduces postoperative shivering. Drugs that reduce shivering usually impair central thermoregulatory control, and may thus be useful for preventing shivering during induction of therapeutic hypothermia. We determined, therefore, whether ondansetron reduces the major autonomic thermoregulatory response thresholds (triggering core temperatures) in humans. METHODS: Control (placebo) and ondansetron infusions at the target plasma concentration of 250 ng ml(-1) were studied in healthy volunteers on two different days. Each day, skin and core temperatures were increased to provoke sweating; then reduced to elicit peripheral vasoconstriction and shivering. We determined the core-temperature sweating, vasoconstriction and shivering thresholds after compensating for changes in mean-skin temperature. Data were analysed using t-tests and presented as means (sds); P<0.05 was taken as significant. RESULTS: Ondensetron plasma concentrations were 278 (57), 234 (55) and 243 (58) ng ml(-1) at the sweating, vasoconstriction and shivering thresholds, respectively; these corresponded to approximately 50 mg of ondansetron which is approximately 10 times the dose used for postoperative nausea and vomiting. Ondansetron did not change the sweating (control 37.4 (0.4) degrees C, ondansetron 37.6 (0.3) degrees C, P=0.16), vasoconstriction (37.0 (0.5) degrees C vs 37.1 (0.3) degrees C; P=0.70), or shivering threshold (36.3 (0.5) degrees C vs 36.3 (0.6) degrees C; P=0.76). No sedation was observed on either study day. CONCLUSIONS: /b>. Ondansetron appears to have little potential for facilitating induction of therapeutic hypothermia.

Meperidine and skin surface warming additively reduce the shivering threshold: a volunteer study

INTRODUCTION: Mild therapeutic hypothermia has been shown to improve outcome for patients after cardiac arrest and may be beneficial for ischaemic stroke and myocardial ischaemia patients. However, in the awake patient, even a small decrease of core temperature provokes vigorous autonomic reactions-vasoconstriction and shivering-which both inhibit efficient core cooling. Meperidine and skin warming each linearly lower vasoconstriction and shivering thresholds. We tested whether a combination of skin warming and a medium dose of meperidine additively would reduce the shivering threshold to below 34 degrees C without producing significant sedation or respiratory depression. METHODS: Eight healthy volunteers participated on four study days: (1) control, (2) skin warming (with forced air and warming mattress), (3) meperidine (target plasma level: 0.9 mug/ml), and (4) skin warming plus meperidine (target plasma level: 0.9 mug/ml). Volunteers were cooled with 4 degrees C cold Ringer lactate infused over a central venous catheter (rate asymptotically equal to 2.4 degrees C/hour core temperature drop). Shivering threshold was identified by an increase of oxygen consumption (+20% of baseline). Sedation was assessed with the Observer's Assessment of Alertness/Sedation scale. RESULTS: Control shivering threshold was 35.5 degrees C +/- 0.2 degrees C. Skin warming reduced the shivering threshold to 34.9 degrees C +/- 0.5 degrees C (p = 0.01). Meperidine reduced the shivering threshold to 34.2 degrees C +/- 0.3 degrees C (p < 0.01). The combination of meperidine and skin warming reduced the shivering threshold to 33.8 degrees C +/- 0.2 degrees C (p < 0.01). There were no synergistic or antagonistic effects of meperidine and skin warming (p = 0.59). Only very mild sedation occurred on meperidine days. CONCLUSION: A combination of meperidine and skin surface warming reduced the shivering threshold to 33.8 degrees C +/- 0.2 degrees C via an additive interaction and produced only very mild sedation and no respiratory toxicity.

The clinical effectiveness of interventions to assist perioperative temperature management for women undergoing Cesarean Section : a systematic review

Background Women undergoing Cesarean Section (CS) are vulnerable to the adverse effects associated with perioperative core temperature drop, in part due to the tendency for CS to be performed under neuraxial anesthesia, blood and fluid loss, and vasodilation. Inadvertent perioperative hypothermia (IPH) is a common condition that affects patients undergoing surgery of all specialties and is detrimental to all age groups, including neonates. Previous systematic reviews on IPH prevention largely focus on either adult or all ages populations, and have mainly overlooked pregnant or CS patients as a distinct group. Not all recommendations made by systematic reviews targeting all adult patients may be transferable to CS patients. Alternative, effective methods for preventing or managing hypothermia in this group would be valuable. Objectives To synthesize the best available evidence in relation to preventing and/or treating hypothermia in mothers after CS surgery. Types of participants Adult patients over the age of 18 years, of any ethnic background, with or without co-morbidities, undergoing any mode of anesthesia for any type of CS (emergency or planned) at healthcare facilities who have received interventions to limit or manage perioperative core heat loss were included. Types of intervention(s) Active or passive warming methods versus usual care or placebo, that aim to limit or manage core heat loss as applied to women undergoing CS were included. Types of studies Randomized controlled trials (RCTs) that met the inclusion criteria, with reduction of perioperative hypothermia a primary or secondary outcome were considered. Types of outcomes Primary outcome: maternal core temperature measured during the preoperative, intraoperative and postoperative phases of care Secondary outcomes: newborn core temperature at birth, umbilical pH obtained immediately after birth, Apgar scores, length of Post Anesthetic Care Unit (PACU) stay, maternal thermal comfort. Search strategy A comprehensive search was undertaken of the following databases from their inception until May 2012: ProQuest, Web of Science, Scopus, Dissertation and Theses PQDT (via ProQuest), Current Contents, CENTRAL, Mednar, OpenGrey, Clinical Trials. There were no language restrictions. Methodological quality Retrieved papers were assessed for methodological quality by two independent reviewers prior to inclusion using JBI software. Disagreements were resolved via consultation with the third reviewer. An assessment of quality of the included papers was also made in relation to five key quality factors. Data collection Two independent reviewers extracted data from the included papers using a previously piloted customized data extraction tool. Results 12 studies with a combined total of 719 participants were included. Three broad intervention groups were identified; intravenous (IV) fluid warming, warming devices, leg wrapping. IV fluid warming, whether administered intraoperatively or preoperatively, was found to be effective at maintaining maternal (but not neonatal) temperature and preventing shivering, but does not improve thermal comfort. The effectiveness of IV fluid warming on Apgar scores and umbilical pH remains unclear. Warming devices, including forced air warming and under body carbon polymer mattresses, were effective at preventing hypothermia and reduced shivering, however were most effective if applied preoperatively. The effectiveness of warming devices to improve thermal comfort remains unclear. Preoperative forced air warming appears to aid maintenance of neonatal temperature, while intraoperative forced air warming does not. Forced air warming was not effective at improving Apgar scores and the effects for umbilical pH remain unclear. Conclusions Intravenous fluid warming, by any method, improves maternal temperature and reduces shivering for women undergoing CS. Preoperative body warming devices also improve maternal temperature, in addition to reducing shivering.

A review of the effects of sedation on thermoregulation : insights for the cardiac catheterisation laboratory

Purpose To examine the effects that the sedative and analgesic medications which are commonly used in the cardiac catheterisation laboratory have on thermoregulation. Design A structured review strategy was used. Methods Medline and CINAHL were searched for published studies and reference lists of retrieved studies were scrutinized for further research. Data were extracted using a standardised extraction tool. Results A total of nine studies examined the effect that sedative and analgesic medications have on thermoregulation. Midazolam has minimal impact on thermoregulation while opioids, dexmedetomidine and propofol markedly decrease vasoconstriction and shivering thresholds. Conclusions Patients who receive sedation in the cardiac catheterisation laboratory may be at risk of hypothermia, due to the use of medications that impair thermoregulation. Further research is required to identify the prevalence of unplanned hypothermia during sedation in the cardiac catheterisation laboratory.

A systematic review of the effectiveness of warming interventions for women undergoing cesarean section

Women undergoing cesarean section are vulnerable to adverse effects associated with inadvertent perioperative hypothermia, but there has been a lack of synthesized evidence for temperature management in this population. This systematic review aimed to synthesize the best available evidence in relation to preventing hypothermia in mothers undergoing cesarean section surgery.

Temperature monitoring of nonanaesthetised patients in a cardiac catheterisation laboratory

Aim and objectives To identify the prevalence that temperature reduced by more than 1°C from pre to post-procedure in a sample of non-anaesthetised patients undergoing procedures in a cardiac catheterisation laboratory. Background Advances in medical technology are minimising the invasiveness of diagnostic tests and treatments for disease, which is correspondingly increasing the number of medical procedures performed without sedation or anaesthesia. Procedural areas in which medical procedures are performed without anaesthesia are typically kept at a cool temperature for staff comfort. As such, there is a need to inform nursing practices in regard to the thermal management of non-anaesthetised patients undergoing procedures in surgical or procedural environments. Design Single-site observational study Methods Patients were included if they had undergone an elective procedure without sedation or anaesthesia in a cardiac catheterisation laboratory. Ambient room temperature was maintained between 18°C and 20°C. Passive warming with heated cotton blankets was applied. Nurses measured body temperature and thermal comfort before and after 342 procedures. Results Mean change in temperature was -0.08°C (Standard deviation 0.43). The reduction in temperature was more than 1°C after 11 procedures (3.2%). One patient whose temperature had reduced more than 1°C after their procedure reported thermal discomfort. A total of 12 patients were observed to be shivering post-procedure (3.6%). No demographic or clinical characteristics were associated with reduction in temperature of more than 1°C from pre to post-procedure. Conclusions Significant reduction in body temperature was rare in our sample of non-anaesthetised patients. Relevance to clinical practice Similar results would likely be found in other procedural contexts during procedures conducted in settings with comparable room temperatures where passive warming can also be applied with limited skin exposure.

Leptin cDNA cloning and its mRNA expression in plateau pikas (Ochotona curzoniae) from different altitudes on Qinghai-Tibet Plateau

Leptin, an adipocyte-derived hormone, plays all important role in body energy homeostasis. Plateau pika (Ochotona curzoniae), an endemic and keystone species living only at 3000-5000 in above sea level oil Qinghai-Tibet Plateau, is a typically high hypoxia and low temperature tolerant mammal with high resting metabolic rate (RMR), non-shivering thermogenesis (NST), and high ratio of oxygen utilization to cope with harsh plateau environment. To explore the molecular mechanism of ecological acclimation in plateau pika, we first cloned pika leptin cDNA and compared its mRNA expression in different altitudes (3200 and 3900 in) using real-time RTPCR (Taqman probe) technology. The full-length pika leptin cDNA was 3015 with 504 bp open-reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. Pika leptin was 70-72% homologous to that of other species and was of similarly structural characteristics with other species. The pika-specific genetic diversity in leptin sequence occurred at twenty sites. With the increase in attitude, there were larger fat store and high level of ob gene expression in plateau pika. Our results indicated that leptin is sensitive to cold and hypoxia plateau environment and may play one of important roles in pika's ecological adaptation to harsh plateau environment. (c) 2006 Elsevier Inc. All rights reserved.

Andrew Marvell's Latin Poetry: From Text to Context (356pp.)

David Norbrook, Review of English Studies 56 (Sept. 2005), 675-6.
‘We have waited a long time for a study of Marvell’s Latin poetry; fortunately, Estelle Haan’s monograph generously makes good the loss ... One of her most intriguing suggestions … is that Marvell may have presented paired poems like ‘Ros’ and ‘On a Drop of Dew’, and the poems to the obligingly named Dr Witty, to his student Maria Fairfax as his own patterns for the pedagogical practice of double translation. Perhaps the most original parts of the book, however, move beyond the familiar canon to cover the generic range of the Latin verse. Haan offers a very full contextualization of the early Horatian Ode to Charles I in seventeenth-century exercises in parodia. In a rewarding reading of the poem to Dr Ingelo she shows how Marvell deploys the language of Ovid’s Tristia to present Sweden as a place of shivering exile, only to subvert this model with a neo-Virgilian celebration of Christina as a virtuous, city-building Dido. She draws extensively on historical as well as literary sources to offer very detailed contextualizations of the poem to Maniban and ‘Scaevola Scotto-Britannus’... This monograph opens up many new ways into the Latin verse, not least because it is rounded off with new texts and prose translations of the Latin poems. These make a substantial contribution in their own right. They are the best and most accurate translations to date (those in Smith’s edition having some lapses); they avoid poeticisms but bring out the structure of the poems' wordplay very clearly. This book brings us a lot closer to seeing Marvell whole.'

Mole-rats from higher altitudes have greater thermoregulatory capabilities

Subterranean mammals (those that live and forage underground) inhabit a challenging microenvironment, with high levels of carbon dioxide and low levels of oxygen. Consequently, they have evolved specialised morphological and physiological adaptations. For small mammals that inhabit high altitudes, the effects of cold are compounded by low oxygen partial pressures. Hence, subterranean mammals living at high altitudes are faced with a uniquely demanding physiological environment, which presumably necessitates additional physiological adjustments. We examined the thermoregulatory capabilities of two populations of Lesotho mole-rat Cryptomys hottentotus mahali that inhabit a 'low' (1600 in) and a 'high' (3200 m) altitude. Mole-rats from the high altitude had a lower temperature of the lower critical point, a broader thermoneutral zone, a lower thermal conductance and greater regulatory non-shivering thermogenesis than animals from the lower altitude. However, minimum resting metabolic rate values were not significantly different between the populations and were low compared with allometric predictions. We suggest that thermoregulatory costs may in part be met by animals maintaining a low resting metabolic rate. High-altitude animals may adjust to their cooler, more oxygen-deficient environment by having an increased non-shivering thermogenesis whilst maintaining low thermal conductance. (c) 2006 Elsevier Inc. All rights reserved.

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.