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https://www.readbyqxmd.com/read/28332020/temperature-effects-on-the-activity-shape-and-storage-of-platelets-from-13-lined-ground-squirrels
#1
Scott Cooper, Sarah Lloyd, Anthony Koch, Xingxing Lin, Katie Dobbs, Thomas Theisen, Matt Zuberbuehler, Kaley Bernhardt, Michael Gyorfi, Tanner Tenpas, Skyler Hying, Sarah Mortimer, Christine Lamont, Marcus Lehmann, Keith Neeves
The objective of this study is to determine how a hibernating mammal avoids the formation of blood clots under periods of low blood flow. A microfluidic vascular injury model was performed to differentiate the effects of temperature and shear rate on platelet adhesion to collagen. Human and ground squirrel whole blood was incubated at 15 or 37 °C and then passed through a microfluidic chamber over a 250-µm strip of type I fibrillar collagen at that temperature and the shear rates of 50 or 300 s(-1) to simulate torpid and aroused conditions, respectively...
March 23, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28332019/comparative-tissue-transcriptomics-highlights-dynamic-differences-among-tissues-but-conserved-metabolic-transcript-prioritization-in-preparation-for-arousal-from-torpor
#2
Lori K Bogren, Katharine R Grabek, Gregory S Barsh, Sandra L Martin
During the hibernation season, 13-lined ground squirrels spend days to weeks in torpor with body temperatures near freezing then spontaneously rewarm. The molecular drivers of the drastic physiological changes that orchestrate and permit torpor are not well understood. Although transcription effectively ceases at the low body temperatures of torpor, previous work has demonstrated that some transcripts are protected from bulk degradation in brown adipose tissue (BAT), consistent with the importance of their protein products for metabolic heat generation during arousal from torpor...
March 23, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28332018/seasonal-loss-and-resumption-of-circadian-rhythms-in-hibernating-arctic-ground-squirrels
#3
Cory T Williams, Maya Radonich, Brian M Barnes, C Loren Buck
Circadian clocks are near universal among organisms and play a key role in coordinating physiological and metabolic functions to anticipate or coincide with predictable daily changes in the physical and social environment. However, whether circadian rhythms persist and are functionally important during hibernation in all mammals is currently unclear. We examined whether circadian rhythms of body temperature (T b) persist during multi-day, steady-state torpor and investigated the association between timing of animal emergence, exposure to light, and resumption of activity and T b rhythms in free-living and captive male arctic ground squirrels...
March 22, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28330964/thermoregulatory-inversion-a-novel-thermoregulatory-paradigm
#4
Domenico Tupone, Georgina Cano, Shaun F Morrison
To maintain core body temperature in mammals, the normal CNS thermoregulatory reflex networks produce an increase in brown adipose tissue (BAT) thermogenesis in response to skin cooling, and an inhibition of the sympathetic outflow to BAT during skin rewarming. In contrast, these normal thermoregulatory reflexes appear to be inverted in hibernation/torpor: thermogenesis is inhibited during exposure to a cold environment, allowing dramatic reductions in core temperature and metabolism, and thermogenesis is activated during skin rewarming, contributing to a return of normal body temperature...
March 22, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28324160/regulation-of-blood-oxygen-transport-in-hibernating-mammals
#5
Inge G Revsbech, Angela Fago
Along with the periodic reductions in O2 requirements of mammalian hibernators during winter, the O2 affinity of the blood of mammalian hibernators is seasonally regulated to help match O2 supply to consumption, contributing to limit tissue oxidative stress, particularly at arousals. Specifically, mammalian hibernators consistently show an overall increase in the blood-O2 affinity, which causes a decreased O2 unloading to tissues, while having similar or lower tissue O2 tensions during hibernation. This overview explores how the decreased body temperature and concentration of red blood cell 2,3-diphosphoglycerate (DPG) that occur in hibernation contribute separately or in combination to the concurrent increase in the O2 affinity of the hemoglobin, the O2 carrier protein of the blood...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324159/hibernation-based-blood-loss-therapy-increases-survivability-of-lethal-hemorrhagic-shock-in-rats
#6
Cecilia E Perez de Lara Rodriguez, Lester R Drewes, Matthew T Andrews
A small-volume (1 ml/kg) resuscitation fluid based on metabolic adaptations in hibernating mammals was optimized using a rat model of hemorrhagic shock. A previous study of this therapy tested only one concentration of three specific components: 4 M D-stereoisomer of beta-hydroxybutyrate (BHB), 43 mM melatonin, and 20% DMSO. In this study, we considered the range of concentrations of BHB and melatonin seen during the physiological extremes of rapid arousal from hypothermic torpor in natural hibernators and applied these to the non-hibernating Sprague-Dawley rat model...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324158/the-influence-of-sex-and-diet-on-the-characteristics-of-hibernation-in-syrian-hamsters
#7
Marie Trefna, Maaike Goris, Cynthia M C Thissen, Vera A Reitsema, Jojanneke J Bruintjes, Edwin L de Vrij, Hjalmar R Bouma, Ate S Boerema, Robert H Henning
Research on deep hibernators almost exclusively uses species captured from the wild or from local breeding. An exception is Syrian hamster (Mesocricetus auratus), the only standard laboratory animal showing deep hibernation. In deep hibernators, several factors influence hibernation quality, including body mass, sex and diet. We examined hibernation quality in commercially obtained Syrian hamsters in relation to body mass, sex and a diet enriched in polyunsaturated fatty acids. Animals (M/F:30/30, 12 weeks of age) were obtained from Harlan (IN, USA) and individually housed at 21 °C and L:D 14:10 until 20 weeks of age, followed by L:D 8:16 until 27 weeks...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324157/water-fat-mri-in-a-hibernator-reveals-seasonal-growth-of-white-and-brown-adipose-tissue-without-cold-exposure
#8
Amanda MacCannell, Kevin Sinclair, Lannette Friesen-Waldner, Charles A McKenzie, James F Staples
Obligate hibernators, such as ground squirrels, display circannual patterns which persist even under constant laboratory conditions, suggesting that they are regulated by endogenous rhythms. Brown adipose tissue (BAT) is important for thermogenesis during periodic arousals from hibernation when core body temperature rises spontaneously from 5 to 37 °C. In most small eutherians BAT growth requires several weeks of cold exposure. We hypothesized that in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), a hibernator, BAT growth is regulated, in part, by an endogenous rhythm and we predicted that this growth would precede the hibernation season without cold exposure...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28322600/renal-mitochondrial-response-to-low-temperature-in-non-hibernating-and-hibernating-species
#9
George J Dugbartey, Maarten C Hardenberg, Wendelinde F Kok, Ate Boerema, Hannah V Carey, James Staples, Robert H Henning, Hjalmar Bouma
SIGNIFICANCE: Therapeutic hypothermia is commonly applied to limit ischemic injury in organ transplantation, during cardiac and brain surgery and after cardiopulmonary resuscitation. In these procedures, the kidneys are particularly at risk for ischemia/reperfusion injury (IRI), likely due to their high rate of metabolism. Although hypothermia mitigates ischemic kidney injury, it is not a panacea. Residual mitochondrial failure is thought to be a key event triggering loss of cellular homeostasis, and potentially cell death...
March 21, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28321493/the-costs-of-locomotor-activity-maximum-body-temperatures-and-the-use-of-torpor-during-the-active-season-in-edible-dormice
#10
Claudia Bieber, Jessica S Cornils, Franz Hoelzl, Sylvain Giroud, Thomas Ruf
Measuring T b during the active season can provide information about the timing of reproduction and the use of short bouts of torpor and may be used as a proxy for the locomotor activity of animals (i.e., maximum T b). This kind of information is especially important to understand life-history strategies and energetic costs and demands in hibernating mammals. We investigated T b throughout the active season in edible dormice (Glis glis), since they (i) have an expensive arboreal life-style, (ii) are known to show short bouts of torpor, and (iii) are adapted to pulsed resources (mast of beech trees)...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28318379/prevalence-and-distribution-of-pseudogymnoascus-destructans-in-michigan-bats-submitted-for-rabies-surveillance
#11
Samantha L Darling, Ailam Lim, Julie R Melotti, Daniel J O'Brien, Steven R Bolin
Since 2006, bat populations in North America have suffered devastating mortality from an emerging disease known as white-nose syndrome (WNS). The causal agent of WNS is the fungus Pseudogymnoascus destructans. In April 2014, WNS was discovered in little brown bats ( Myotis lucifugus ) in Michigan, and has since been documented in 12 counties. Because current surveillance for WNS focuses primarily on mine-hibernating species in winter, it is subject geographic, species, and seasonal bias. To investigate species affected and potential associations of gender, seasonal life cycle, and region with P...
March 20, 2017: Journal of Wildlife Diseases
https://www.readbyqxmd.com/read/28298331/expression-of-leptin-receptor-in-the-oviduct-of-chinese-brown-frog-rana-dybowskii
#12
Liqin Xi, Yuning Liu, Zeqi Tang, Xia Sheng, Haolin Zhang, Qiang Weng, Meiyu Xu
The oviduct of Chinese brown frog (Rana dybowskii) expands specifically during pre-hibernation instead of in the breeding period. In this study, we investigated the expression of leptin receptor (Ob-Rb) in Rana dybowskii oviduct during the breeding period and pre-hibernation. Histologically, the oviduct of Rana dybowskii consists of glandular cells, tubule lumen and epithelial cells. The oviductal weight and pipe diameter also revealed significant differences, which were higher in pre-hibernation than that of the breeding period...
March 15, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28296283/effects-of-transendocardial-cd34-cell-transplantation-on-diastolic-parameters-in-patients-with-nonischemic-dilated-cardiomyopathy
#13
Mojca Bervar, Mirta Kozelj, Gregor Poglajen, Matjaz Sever, Gregor Zemljic, Sabina Frljak, Marko Cukjati, Peter Cernelc, François Haddad, Bojan Vrtovec
We sought to evaluate the physiological background and the effects of CD34(+) cell transplantation on diastolic parameters in nonischemic dilated cardiomyopathy patients (DCM). We enrolled 38 DCM patients with NYHA class III and LVEF <40% who underwent transendocardial CD34(+) cell transplantation. Peripheral blood CD34(+) cells were mobilized by G-CSF, collected via apheresis, and injected transendocardially in the areas of myocardial hibernation. Patients were followed for 1 year. At baseline, estimated filling pressures were significantly elevated (E/e'≥15) in 18 patients (Group A), and moderately elevated (E/e'<15) in 20 patients (Group B)...
March 11, 2017: Stem Cells Translational Medicine
https://www.readbyqxmd.com/read/28281641/hnf-4-participates-in-the-hibernation-associated-transcriptional-regulation-of-the-chipmunk-hibernation-related-protein-gene
#14
Daisuke Tsukamoto, Michihiko Ito, Nobuhiko Takamatsu
The chipmunk hibernation-related protein 25 (HP-25) is involved in the circannual control of hibernation in the brain. The liver-specific expression of the HP-25 gene is repressed in hibernating chipmunks under the control of endogenous circannual rhythms. However, the molecular mechanisms that differentially regulate the HP-25 gene during the nonhibernation and hibernation seasons are unknown. Here, we show that the hibernation-associated HP-25 expression is regulated epigenetically. Chromatin immunoprecipitation analyses revealed that significantly less hepatocyte nuclear receptor HNF-4 bound to the HP-25 gene promoter in the liver of hibernating chipmunks compared to nonhibernating chipmunks...
March 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28279384/can-functional-testing-for-ischemia-and-viability-guide-revascularization
#15
REVIEW
Lisa M Mielniczuk, Gabor G Toth, Joe X Xie, Bernard De Bruyne, Leslee J Shaw, Rob S Beanlands
Cardiac imaging procedures are a cornerstone of the diagnosis and management of patients with cardiac disease. The optimal management of the patient with stable ischemic heart disease or ischemic heart failure often rests on the totality of symptom burden, patient risk, and disease severity, whether assessed anatomically or functionally. Recent trials have demonstrated the power of flow measurements to direct revascularization as well as the strengths and limitations of ischemia and viability/hibernation imaging as markers of risk to direct interventions...
March 2017: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/28277320/subcellular-energetics-and-metabolism-potential-therapeutic-applications
#16
Robert H Thiele
Part I of this review discussed the similarities between embryogenesis, mammalian adaptions to hypoxia (primarily driven by hypoxia-inducible factor-1 [HIF-1]), ischemia-reperfusion injury (and its relationship with reactive oxygen species), hibernation, diving animals, cancer, and sepsis, and it focused on the common characteristics that allow cells and organisms to survive in these states. Part II of this review describes techniques by which researchers gain insight into subcellular energetics and identify potential future tools for clinicians...
March 8, 2017: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/28270617/mechanisms-regulating-angiogenesis-underlie-seasonal-control-of-pituitary-function
#17
Jennifer Castle-Miller, David O Bates, Domingo J Tortonese
Seasonal changes in mammalian physiology, such as those affecting reproduction, hibernation, and metabolism, are controlled by pituitary hormones released in response to annual environmental changes. In temperate zones, the primary environmental cue driving seasonal reproductive cycles is the change in day length (i.e., photoperiod), encoded by the pattern of melatonin secretion from the pineal gland. However, although reproduction relies on hypothalamic gonadotrophin-releasing hormone output, and most cells producing reproductive hormones are in the pars distalis (PD) of the pituitary, melatonin receptors are localized in the pars tuberalis (PT), a physically and functionally separate part of the gland...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28270601/resuscitation-of-pseudomonas-aeruginosa-from-dormancy-requires-hibernation-promoting-factor-pa4463-for-ribosome-preservation
#18
Tatsuya Akiyama, Kerry S Williamson, Robert Schaefer, Shawna Pratt, Connie B Chang, Michael J Franklin
Pseudomonas aeruginosa biofilm infections are difficult to treat with antibiotic therapy in part because the biofilms contain subpopulations of dormant antibiotic-tolerant cells. The dormant cells can repopulate the biofilms following alleviation of antibiotic treatments. While dormant, the bacteria must maintain cellular integrity, including ribosome abundance, to reinitiate the de novo protein synthesis required for resuscitation. Here, we demonstrate that the P. aeruginosa gene PA4463 [hibernation promoting factor (HPF)], but not the ribosome modulation factor (PA3049), is required for ribosomal RNA preservation during prolonged nutrient starvation conditions...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28257856/the-role-of-global-histone-post-translational-modifications-during-mammalian-hibernation
#19
Shannon N Tessier, Bryan E Luu, Jeffrey C Smith, Kenneth B Storey
Mammalian hibernators must cope with hypothermia, ischemia-reperfusion, and finite fuel reserves during days or weeks of continuous torpor. One means of lowering ATP demands during hibernation involves substantial transcriptional controls. The present research analyzed epigenetic regulatory factors as a means of achieving transcriptional control over cycles of torpor-arousal. This study analyzes differential regulation of select histone modifications (e.g. phosphorylation, acetylation, methylation), and identifies post-translational modifications on purified histones using mass spectrometry from thirteen-lined ground squirrels (Ictidomys tridecemlineatus)...
February 28, 2017: Cryobiology
https://www.readbyqxmd.com/read/28251799/diet-affects-arctic-ground-squirrel-gut-microbial-metatranscriptome-independent-of-community-structure
#20
Jasmine J Hatton, Timothy J Stevenson, C Loren Buck, Khrystyne N Duddleston
We examined the effect of diet on pre-hibernation fattening and the gut microbiota of captive arctic ground squirrels (Urocitellus parryii). We measured body composition across time and gut microbiota density, diversity, and function prior to and after five-weeks on control, high-fat, low-fat (18%, 40%, and 10% energy from fat, respectively), or restricted calorie (50% of control) diets. Squirrels fattened at the same rate and to the same degree on all diets. Additionally, we found no differences in gut microbiota diversity or short chain fatty acid production across time or with diet...
March 2, 2017: Environmental Microbiology
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