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American Journal of Physiology. Regulatory, Integrative and Comparative Physiology

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https://www.readbyqxmd.com/read/28903915/obesity-modulates-diaphragm-curvature-in-subjects-with-and-without-copd
#1
Aladin M Boriek, Michael A Lopez, Cristina Velasco, Azam A Bakir, Anna Frolov, Shari Wynd, Tony G Babb, Nicola A Hanania, Eric A Hoffman, Amir Sharafkhaneh
BACKGROUND: Obesity is a common co-morbidity of COPD and has been associated with worse outcomes. However, it is unknown whether the interaction between obesity and COPD modulates diaphragm shape and consequently its function. The body mass index has been used as a correlate of obesity. We tested the hypothesis that the shape of the diaphragm muscle and size of the ring of its insertion in Non-COPD and COPD subjects are modulated by BMI. METHODS: We recruited 48 COPD patients with post-bronchiodilator FEV1/FVC < 0...
September 13, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28903914/long-term-treatment-with-the-ghrelin-receptor-antagonist-d-lys3-ghrp-6-does-not-improve-glucose-homeostasis-in-non-obese-diabetic-mkr-mice
#2
Rasha Mosa, Lili Huang, Hongzhuo Li, Michael Grist, Derek LeRoith, Chen Chen
Ghrelin secretion has been associated with increased caloric intake and adiposity. The expressions of ghrelin and its receptor (GHS-R1a) in pancreas have raised the interest about the role of ghrelin in glucose homeostasis. Most of the studies showed that ghrelin promoted hyperglycaemia and inhibited insulin secretion. This raised the interest in using GHS-R1a antagonists as therapeutic targets for type 2 diabetes. Available data of GHS-R antagonists are on a short-term basis. Moreover, the complexity of GHS-R1a signalling makes it difficult to understand the mechanism of action of GHS-R1a antagonists...
September 13, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28877873/the-in-vitro-zebrafish-heart-as-a-model-to-investigate-the-chronotropic-effects-of-vapor-anesthetics
#3
Matthew R Stoyek, Michael K Schmidt, Florentin M Wilfart, Roger P Croll, Frank M Smith
In addition to their intended clinical actions, all general anesthetic agents in common use have detrimental intra- and post-surgical side effects on organs and systems including the heart. The major cardiac side effect of anesthesia is bradycardia, which increases the probability of insufficient systemic perfusion during surgery. These side effects also occur in all vertebrate species so far examined, but the underlying mechanisms are not clear. The zebrafish heart is a powerful model for studying cardiac electrophysiology, employing the same pacemaker system and neural control as do mammalian hearts...
September 6, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28877872/insulin-sensitivity-leptin-adiponectin-resistin-and-testosterone-in-adult-male-and-female-rats-after-maternal-neonatal-separation-and-environmental-stress
#4
Hershel Raff, Brian Hoeynck, Mack Jablonski, Cole Leonovicz, Jonathan M Phillips, Ashley L Gehrand
Care of premature infants often requires parental and caregiver separation particularly during hypoxic and hypothermic episodes. We have established a neonatal rat model of human prematurity involving maternal-neonatal separation and hypoxia with spontaneous hypothermia prevented with external heat. Adults previously exposed to these neonatal stressors show a sex difference in the insulin and glucose response to arginine stimulation suggesting a state of insulin resistance. The current study used this cohort of adult rats to evaluate insulin resistance (Homeostatic Model Assessment of Insulin Resistance [HOMA-IR]), plasma adipokines (reflecting insulin resistance states), and testosterone...
September 6, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28877871/comparative-nmr-and-nirs-analysis-of-oxygen-dependent-metabolism-in-exercising-finger-flexor-muscles
#5
David Bendahan, Benjamin Chatel, Thomas Jue
Muscle contraction requires the physiology to adapt rapidly to meet the surge in energy demand. To investigate the shift in metabolic control, especially between oxygen and metabolism, researchers often depend on near infrared spectroscopy (NIRS) to measure non-invasively the tissue O2 Because NIRS detects the overlapping myoglobin (Mb) and hemoglobin (Hb) signals in muscle, interpreting the data as an index of cellular or vascular O2 requires deconvoluting the relative contribution. Currently, many in the NIRS field ascribe the signal to Hb...
September 6, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28877870/circadian-variability-of-body-temperature-responses-to-methamphetamine
#6
Abolhassan Behrouzvaziri, Maria V Zaretskaia, Daniel Edward Rusyniak, Dmitry V Zaretsky, Yaroslav I Molkov
Vital parameters of living organisms exhibit circadian rhythmicity. Although rats are nocturnal animals, most of the studies involving rats are performed during the day. The objective of this study was to examine the circadian variability of the body temperature responses to methamphetamine (Meth). Body temperature was recorded in male Sprague-Dawley rats received Meth (1 or 5 mg/kg) or saline at 10am or 10pm. The baseline body temperature at night was 0.8ºC higher than during the day. Both during the day and at night 1 mg/kg of Meth induced monophasic hyperthermia...
September 6, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28877869/hemoglobin-polymerization-via-disulfide-bond-formation-in-the-hypoxia-tolerant-turtle-trachemys-scripta-implications-for-antioxidant-defense-and-o2-transport
#7
Asbjørn Graver Petersen, Steen Vang Petersen, Sebastian Frische, Srdja Drakulic, Monika M Golas, Bjoern Sander, Angela Fago
The ability of many reptilian hemoglobins (Hbs) to form high-molecular weight polymers, albeit known for decades, has not been investigated in detail. Given that turtle Hbs often contain a high number of cysteine (Cys), potentially contributing to the red blood cell defense against reactive oxygen species, we have examined whether polymerization of Hb could occur via intermolecular disulfide bonds in red blood cells of freshwater turtle Trachemys scripta, a species that is highly tolerant of hypoxia and oxidative stress...
September 6, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28855180/diet-induced-obesity-accelerates-blood-lactate-accumulation-of-rats-in-response-to-incremental-exercise-to-maximum
#8
Chiao-Nan Joyce Chen, Yi-Hung Liao, Shang-Ying Lin, Jun-Xian Yu, Zhen-Jie Li, Yu-Chieh Lin, Gwo-Jyh Chang, Chung-Hao Lin, Alice May-Kuen Wong
AIM: Blood lactate increases during incremental exercise at high-intensity workloads and limited exercise capacity is a characteristic of obese animals. This study examined whether blood lactate changes in response to incremental exercise is disrupted in obese animals. Muscular and hepatic proteins that are critical in lactate metabolism were also investigated. METHODS: Rats were randomized to either standard chow (control) or high fat diet (HFD) groups. All animals underwent an incremental treadmill test after 14 weeks of diet intervention...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28855179/face-cooling-increases-blood-pressure-during-central-hypovolemia
#9
Blair D Johnson, James R Sackett, Suman Sarker, Zachary J Schlader
A reduction in central blood volume can lead to cardiovascular decompensation (i.e., failure to maintain blood pressure). Cooling the forehead and cheeks using ice water raises blood pressure. Therefore, face cooling (FC) could be used to mitigate decreases in blood pressure during central hypovolemia. PURPOSE: We tested the hypothesis that FC during central hypovolemia induced by lower body negative pressure (LBNP) would increase blood pressure. METHODS: Ten healthy participants (22±2 years, 3 women) completed two randomized LBNP trials on separate days...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28855178/baroreflex-and-neurovascular-responses-to-skeletal-muscle-mechanoreflex-activation-in-humans-an-exercise-in-integrative-physiology
#10
Rachel C Drew
Cardiovascular adjustments to exercise, resulting in increased blood pressure (BP) and heart rate (HR), occur in response to activation of several neural mechanisms - the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem, and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow directed to the kidneys, causing renal vasoconstriction, a key reflex mechanism involved in blood flow redistribution during increased skeletal muscle work...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28855177/small-functional-if-current-in-sinoatrial-pacemaker-cells-of-the-brown-trout-salmo-trutta-fario-heart-despite-strong-expression-of-hcn-channel-transcripts
#11
Minna Hassinen, Jaakko Haverinen, Matti Vornanen
Funny current (If), formed by hyperpolarization-activated HCN channels, is supposed to be crucial for membrane clock regulating the cardiac pacemaker mechanism. We examined the presence and activity of HCN channels in the brown trout (Salmo trutta fario) sinoatrial (SA) pacemaker cells, and their putative role in heart rate (fH) regulation. Six HCN transcripts (HCN1, HCN2a, HCN2ba, HCN2bb, HCN3 and HCN4) were expressed in the brown trout heart. The total HCN transcript abundance was 4.0 and 4.9 times higher in SA pacemaker tissue than in atrium and ventricle, respectively...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28855176/use-of-radiotelemetry-to-assess-perinatal-cardiac-function-in-the-ovine-fetus-and-newborn
#12
Andrew Antolic, Charles E Wood, Maureen Keller-Wood
The late gestation fetal ECG (fECG) has traditionally been difficult to characterize due to the low fECG signal relative to high maternal noise. Although new technologies have improved the feasibility of its acquisition and separation, little is known about its development in late gestation, a period in which the fetal heart undergoes extensive maturational changes. Here, we describe a method for the chronic implantation of radiotelemetry devices into late gestation ovine fetuses to characterize parameters of the fECG following surgery, throughout late gestation, and in the perinatal period...
August 30, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835451/obesity-induced-vascular-inflammation-involves-elevated-arginase-activity
#13
Lin Yao, Anil Bhatta, Zhimin Xu, Jijun Chen, Haroldo A Toque, Yongjun Chen, Yiming Xu, Zsolt Bagi, Rudolf Lucas, Yuqing Huo, Ruth B Caldwell, Robert W Caldwell
Obesity-induced vascular dysfunction involves pathological remodeling of the visceral adipose tissue (VAT) and increased inflammation. Our previous studies showed that arginase 1 (A1) in endothelial cells (EC) is critically involved in obesity-induced vascular dysfunction. We tested the hypothesis that EC A1 activity also drives obesity-related VAT remodeling and inflammation. Our studies utilized wild-type and EC-A1 knockout (KO) mice made obese by high fat/high sucrose (HFHS) diet. HFHS diet induced increases in body weight, fasting blood glucose, and VAT expansion...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835450/the-differential-role-of-reactive-oxygen-species-in-early-and-late-stages-of-cancer
#14
Mohamad Assi
The large doses of vitamin C and E and β-carotene used to reduce reactive oxygen species (ROS) production and oxidative damages in cancerous tissue, have produced disappointing and contradictory results. This therapeutic conundrum was attributed to the double-faced role of ROS, notably, their ability to induce either proliferation or apoptosis of cancer cells. However, for a ROS-inhibitory approach to be effective, it must targets ROS when they induce proliferation rather than apoptosis. Based on recent advances in redox biology, this review underlined a differential regulation of pro- and antioxidant system, respective to the stage of cancer...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835449/fluorescence-quenching-by-metal-centered-porphyrins-and-poryphyrin-enzymes
#15
Kenneth R Olson, Yan Gao, Faihaan Arif, Kanika Arora, Shivali Patel, Eric R DeLeon, Karl D Straub
Fluorescence spectroscopy and microscopy has been used extensively to monitor biomolecules, especially reactive oxygen species (ROS) and more recently reactive sulfide (RSS) species. Nearly all fluorophores are either excited by or emit light between 450 and 550 nm which is similar to the absorbance of heme proteins and metal-centered porphyrins. Here we examined the effects of catalase (Cat), reduced and oxidized hemoglobin (Hb and metHb), albumin (alb), manganese (III) Tetrakis (4-Benzoic Acid) porphyrin chloride (MnTBAP), iron proto-porphyrin IX (hemin) and copper proto-porphyrin IX (CuPPIX) on the fluorescence properties of fluorescein...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835448/cyclical-blood-flow-restriction-resistance-exercise-a-potential-parallel-to-remote-ischemic-preconditioning
#16
Justin Daniel Sprick, Caroline A Rickards
Remote ischemic preconditioning (RIPC) is characterized by the cyclical application of limb blood flow restriction and reperfusion, and has been shown to protect vital organs during a subsequent ischemic insult. Blood flow restriction exercise (BFRE) similarly combines bouts of blood flow restriction with low-intensity exercise and thus could potentially emulate the protection demonstrated by RIPC. One concern with BFRE, however, is the potential for an augmented rise in sympathetic outflow, due to greater activation of the exercise pressor reflex...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835447/combining-remote-ischemic-preconditioning-and-aerobic-exercise-a-novel-adaptation-of-blood-flow-restriction-exercise
#17
Justin Daniel Sprick, Caroline A Rickards
Remote ischemic preconditioning (RIPC) can attenuate tissue damage sustained by ischemia-reperfusion injury. Blood flow restriction exercise (BFRE) restricts blood flow to exercising muscles. We implemented a novel approach to BFRE with cyclical bouts of blood flow restriction-reperfusion, reflecting the RIPC model. A concern about BFRE, however, is potential amplification of the exercise pressor reflex, which could be unsafe in at-risk populations. We hypothesized that cyclical BFRE would elicit greater increases in sympathetic outflow and arterial pressure than conventional exercise (CE), performed at the same relative intensity...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28835446/white-nose-syndrome-increases-torpid-metabolic-rate-and-evaporative-water-loss-in-hibernating-bats
#18
Liam P McGuire, Heather W Mayberry, Craig K R Willis
Fungal diseases of wildlife typically manifest as superficial skin infections but can have devastating consequences for host physiology and survival. White-nose syndrome (WNS) is a fungal skin disease that has killed millions of hibernating bats in North America since 2007. Infection with the fungus Pseudogymnoascus destructans causes bats to rewarm too often during hibernation, but the cause of increased arousal rates remains unknown. Based on data from studies of captive and free-living bats, two mechanistic models have been proposed to explain disease processes in WNS...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28814391/filling-the-void-a-role-for-exercise-induced-bdnf-and-brain-amyloid-precursor-protein-processing
#19
Rebecca Ek MacPherson
Inactivity, obesity, and insulin resistance are significant risk factors for the development of Alzheimer's disease (AD). Several studies have demonstrated that diet induced obesity, inactivity, and insulin resistance exacerbates neuropathological hallmarks of AD. The aggregation of beta-amyloid peptides is one of these hallmarks. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting enzyme in amyloid precursor protein (APP) processing, leading to beta-amyloid peptide formation...
August 16, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28814390/the-physiological-and-metabolic-differences-between-visceral-and-subcutaneous-adipose-tissues-in-nile-tilapia-oreochromis-niloticus
#20
Ya-Wen Wang, Ji-Lei Zhang, Jian-Gang Jiao, Xiao-Xia Du, Samwel Mchele Limbu, Fang Qiao, Mei-Ling Zhang, Dong-Liang Li, Zhen-Yu Du
BACKGROUND: Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SCAT) have different structures and metabolic functions, and play different roles in the regulation of mammal systemic endocrine. However, little is known about morphology and physiological and metabolic functions between VAT and SCAT in fish. METHODS: We compared the morphological, physiological and biochemical characteristics of VAT and SCAT in Nile Tilapia and measured their functions in energy intake flux, lipolytic ability, and gene expression patterns...
August 16, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
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