bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of carbohydrate availability following exercise on whole-body insulin action
Authors: Holtz Kaila A. , Stephens Brooke R. , Sharoff Carrie G. , Chipkin Stuart R. , Braun Barry 
Published: October 2008

One bout of exercise enhances insulin-stimulated glucose uptake (insulin action), but the effect is blunted by consumption of carbohydrate-containing food after exercise. The independent roles of energy and carbohydrate in mediating post-exercise insulin action have not been systematically evaluated in humans. The purpose of this study was to determine if varying carbohydrate availability, with energy intake held constant, mediates post-exercise insulin action. Ten young (21 ± 2 y, overweight (body fat 37% ± 3%) men and women completed 3 conditions in random order: (i) no-exercise (BASE), (ii) exercise with energy balance but carbohydrate deficit (C-DEF), and (iii) exercise with energy and carbohydrate balance (C-BAL). In the exercise conditions, subjects expended 30% of total daily energy expenditure on a cycle ergometer at 70% VO2 peak. Following exercise, subjects consumed a meal that replaced expended energy (~3000 kJ) and was either balanced (intake = expenditure) or deficient (–100 g) in carbohydrate. Twelve hours later, insulin action was measured by continuous infusion of glucose with stable isotope tracer (CIG-SIT). Changes in insulin action were evaluated using a one-way ANOVA with repeated measures. During CIG-SIT, non-oxidative glucose disposal (i.e., glucose storage) was higher in C-DEF than in BASE (27.2 ± 3.2 vs. 16.9 ± 3.5 µmol·L–1·kg–1·min–1, p < 0.05). Conversely, glucose oxidation was lower in C-DEF (8.6 ± 1.3 µmol·L–1·kg–1·min–1) compared with C-BAL (12.2 ± 1.2 µmol·L–1·kg–1·min–1), and BASE (17.1 ± 2.2 µmol·L–1·kg–1·min–1), p < 0.05). Fasting fat oxidation was higher in C-DEF than in BASE (109.8 ± 10.5 vs. 80.7 ± 9.6 mg·min–1, p < 0.05). In C-DEF, enhanced insulin action was correlated with the magnitude of the carbohydrate deficit (r = 0.82, p < 0.01). Following exercise, re-feeding expended energy, but not carbohydrate, increased fasting fat oxidation, and shifted insulin-mediated glucose disposal toward increased storage and away from oxidation.
Diastolic Doppler flow and tissue Doppler velocities during, and in recovery from, low-intensity supine exercise
Authors: Giannaki Christoforos D. , Oxborough David , George Keith 
Published: October 2008

Recent studies have reported evidence of both a short-term and a more sustained reduction in left ventricular diastolic function after prolonged strenuous exercise. Interpretation of this data is confounded by alterations in heart rate (HR) post-exercise. The purpose of this study was to investigate the association between HR and diastolic function during recovery from supine exercise, and to reassess the impact of increasing HR on early diastolic flow and tissue velocities during supine exercise. Repeat echocardiograms in 16 young, trained, volunteers were obtained at rest (50 ± 6 beats·min–1), during steady-state supine cycling at HR of 60, 80, and 100 beats·min–1, and then during supine recovery at HR of 80 and 60 beats·min–1. Doppler flow velocities and tissue Doppler myocardial annular velocities were recorded in early (E and E′, respectively) and late diastole (A and A′, respectively). The ratios E/A, E′/A′, and E/E′ were calculated. Data were compared via analyses of variance (ANOVA; exercise) and t tests (recovery). Peak E, A, E′, and A′ all increased in line with HR during exercise (p < 0.05) although relatively greater changes in A and A′ resulted in a significant decline in E/A and E′/A′ with increasing HR (p < 0.05). During recovery E, A, E′, and A′ all declined from peak values during exercise (p < 0.05). At 80 beats·min–1, flow and tissue Doppler data were still elevated above resting values and only A was significantly reduced compared with assessments made at the same HR during exercise. Diastolic flow and tissue velocities tended to increase (during supine exercise) and return to baseline (during recovery from exercise) in line with changes in HR. The interpretation of diastolic functional indices measured after physical exertion should be made in light of the present data.
Overnight hypoxic exposure and glucagon-like peptide-1 and leptin levels in humans
Authors: Snyder Eric M. , Carr Richard D. , Deacon Carolyn F. , Johnson Bruce D. 
Published: October 2008

Altitude exposure has been associated with loss of appetite and weight loss in healthy humans; however, the endocrine factors that contribute to these changes remain unclear. Leptin and glucagon-like peptide-1 (GLP-1) are peptide hormones that contribute to the regulation of appetite. Leptin increases with hypoxia; however, the influence of hypoxia on GLP-1 has not been studied in animals or humans to date. We sought to determine the influence of normobaric hypoxia on plasma leptin and GLP-1 levels in 25 healthy humans. Subjects ingested a control meal during normoxia and after 17 h of exposure to normobaric hypoxia (fraction of inspired oxygen of 12.5%, simulating approximately 4100 m). Plasma leptin was assessed before the meal, and GLP-1 was assessed premeal, at 20 min postmeal, and at 40 min postmeal. We found that hypoxia caused a significant elevation in plasma leptin levels (normoxia, 4.9 ± 0.8 pg·mL–1; hypoxia, 7.7 ± 1.5 pg·mL–1; p < 0.05; range, –16% to 190%), no change in the average GLP-1 response to hypoxia, and only a small trend toward an increase in GLP-1 levels 40 min postmeal (fasting, 15.7 ± 0.9 vs 15.9 ± 0.7 pmol·L–1; 20 min postmeal, 21.7 ± 0.9 vs 21.8 ± 1.2 pmol·L–1; 40 min postmeal, 19.5 ± 1.2 vs. 21.0 ± 1.2 pmol·L–1 for normoxia and hypoxia, respectively; p > 0.05 normoxia vs hypoxia). There was a correlation between SaO2 and leptin after the 17 h exposure (r = 0.45; p < 0.05), but no relation between SaO2 and GLP-1. These data confirm that leptin increases with hypoxic exposure in humans. Further study is needed to determine the influence of hypoxia and altitude on GLP-1 levels.
A randomized controlled crossover trial of the effect of ginseng consumption on the immune response to moderate exercise in healthy sedentary men
Authors: Biondo Patricia D. , Robbins Sarah J. , Walsh Jennifer D. , McCargar Linda J. , Harber Vicki J. , Field Catherine J. 
Published: October 2008

Ginseng is a popular herbal remedy that is reputed to increase resistance to stress and improve immune function. Regular exercise results in acute physiologic stress that affects the immune response. This study was conducted to investigate the effects of daily consumption of a standardized ginsenoside-containing North American ginseng (Panax quinquefolius) extract on immune function before, during, and after a moderate-exercise protocol in healthy sedentary men. Ten healthy males were randomized to receive either ginseng (1125 mg·d–1) or placebo for 35 days. After a 3 month washout period, subjects received the opposite treatment for another 35 days. An exercise test and blood collection were performed at the end of each treatment period. Immune parameters and blood hormone levels were measured before, during, and after the exercise stress protocol. Ginseng treatment reduced the peripheral blood concentration of CD8+ T cells and increased mitogen-stimulated T cell production of interleukin-2 ex vivo. Ginseng had no effect on total white blood cell counts; on concentrations of neutrophils, monocytes, or lymphocytes (CD3+, CD4+, CD16+, CD20+); on lymphocyte proliferation; or on neutrophil oxidative burst. Ginseng did not significantly affect exercise-induced changes in plasma concentrations of lactate, insulin, cortisol, or growth hormone. The consumption of ginseng for 5 weeks had a limited effect on the immune response to an acute exercise protocol.
Exercise pretraining attenuates endotoxin-induced hemodynamic alteration in type I diabetic rats
Authors: Hung Ching-Hsia , Chen Yu-Wen , Shao Dong-Zi , Chang Che-Ning , Tsai Yung-Yuh , Cheng Juei-Tang 
Published: October 2008

Higher expression of heat shock protein 72 (HSP72) reduces the mortality rate and organ damage in septic shock and prevents cardiac mitochondrial dysfunction due to lipopolysaccharide (LPS). Our hypothesis is that exercise preconditioning may increase the expression of HSP72 in heart and the nucleus tractus solitarii (NTS) of the brain to alleviate the cardiovascular dysfunction in type I diabetic rats receiving endotoxin. Wistar rats were randomly assigned to the following groups: sedentary normal, sedentary type I diabetic rats, and type I diabetic rats with exercise training. The trained rats ran on a treadmill 5 d·week–1, 30–60 min·d–1, at an intensity of 1.0 mile·h–1 (1 mile = 1.6 km) over a 3 week period. Twenty-four hours after the last training session, we compared the temporal profiles of mean arterial pressure, heart rate, cardiac output, stroke volume, and serum tumor necrosis factor α level in rats receiving an injection of LPS. In addition, HSP72 expression in heart and NTS from each group was determined. We found that HSP72 expression in the heart and NTS was significantly increased in diabetic rats with exercise training. After administration of LPS, the survival time was significantly longer in diabetic rats with exercise training. Additionaly, serum tumor necrosis factor α levels decreased as compared with those rats not receiving exercise training. Exercise training also diminished cardiovascular dysfunction in diabetic rats during endotoxemia. These data suggest that exercise may increase the expression of HSP72 in the heart and NTS to protect against the high mortality rate and attenuate cardiovascular dysfunction in diabetic rats during endotoxemia.
Contraction frequency modulates muscle fatigue and the rate of myoglobin desaturation during incremental contractions in humans
Authors: Wigmore Danielle M. , Befroy Douglas E. , Lanza Ian R. , Kent-Braun Jane A. 
Published: October 2008

The metabolic cost of force production, and therefore the demand for oxygen, increases with intensity and frequency of contraction. This study investigated the interaction between fatigue and oxygenation, as reflected by deoxymyoglobin (dMb), during slow and rapid rhythmic isometric contractions having the same duty cycles and relative force–time integrals (FTIs). We used1H magnetic resonance spectroscopy and measures of dorsiflexor muscle force to compare dMb and fatigue (fall of maximal voluntary force, MVC) in 11 healthy adults (29 ± 7 y) during 16 min of slow (4 s contraction, 6 s relaxation) and rapid (1.2 s, 1.8 s) incremental (10%–80% MVC) contractions. We tested the hypotheses that (i) the rate of Mb desaturation would be faster in rapid than in slow contractions and (ii) fatigue, Mb desaturation, and the fall in FTI would be greater, and PO2(oxygen tension) lower, at the end of rapid contractions than at the end of slow contractions. Although dMb increased more quickly during rapid contractions (p = 0.05), it reached a plateau at a similar level in both protocols (~42% max, p = 0.49), likely due to an inability to further increase force production and thus metabolic demand. Despite the similar dMb at the end of both protocols, fatigue was greater in rapid (56.6% ± 2.7% baseline) than in slow (69.5% ± 4.0%, p = 0.01) contractions. These results indicate that human skeletal muscle fatigue during incremental isometric contractions is in part a function of contraction frequency, possibly due to metabolic inhibition of the contractile process.
Splenic constriction during isometric handgrip exercise in humans
Authors: Frances Maria F. , Dujic Zeljko , Shoemaker J. Kevin 
Published: October 2008

During the first minute of a moderate-intensity isometric handgrip (HG) exercise, there is an increase in stroke volume and cardiac output that occurs without any change in systemic vascular conductance. Although the mechanism of increased venous return is not yet known, current focus has been placed on the constriction of visceral organs. The human spleen represents a compliant organ with high perfusion that constricts during the rather severe stresses of maximal exercise, a diving reflex, or prolonged apnea. This study tested the hypothesis that spleen constriction occurs during isometric HG exercise. Eight participants performed a 1 min isometric HG test at 40% maximum voluntary contraction. Splenic length and width were measured (with ultrasound imaging) after 1 min of exercise, and volume was calculated. To investigate the reflex specificity of this response, spleen dimensions were also measured during 4 min of lower-body negative pressure (LBNP; –20 mm Hg). To test the additional impact of altered breathing and intra-abdominal pressures during the HG, measures were also taken during Valsalva’s manoeuvre (VM) at 30 mm Hg. Compared with baseline, both length and width of the spleen were reduced by 0.20 to 0.55 cm (or 4.44%–6.09%; p < 0.05) during each test. This resulted in relative reductions in splenic volume of 13 ± 1% (HG), 9% ± 7% (LBNP) and 18% ± 7% (VM) (p < 0.05; all mean ± SD). It was concluded that the spleen can constrict during the first minute of isometric HG exercise.
Overweight children and adolescents referred for weight management: are they meeting lifestyle behaviour recommendations?
Authors: Ball Geoff D.C. , Lenk Julie M. , Barbarich Bobbi N. , Plotnikoff Ronald C. , Fishburne Graham J. , Mackenzie Kelly A. , Willows Noreen D. 
Published: October 2008

Adopting and maintaining healthy lifestyle behaviours can help overweight boys and girls manage their weight and reduce obesity-related health risks. However, we currently know very little about the lifestyle habits of overweight children and adolescents referred for weight management in Canada and whether or not they are meeting current lifestyle recommendations. The objectives of this study were (i) to determine the demographic characteristics and lifestyle behaviours of overweight children and adolescents referred for clinical weight management, and (ii) to examine sex (boys vs. girls) and (or) age (child vs. youth) differences with respect to the achievement of lifestyle behaviour recommendations. Overweight (age- and sex-specific body mass index ≥ 85th percentile) children (n = 27 girls, n = 24 boys) and adolescents (n = 29 girls, n = 19 boys) were referred to and enrolled in weight-management programs at the Pediatric Centre for Weight and Health (PCWH) at the Stollery Children’s Hospital (Edmonton, Alta.) from January 2006–September 2007. Information was collected at intake regarding demography, anthropometry, and lifestyle behaviours before participants started a formal weight-management program. Lifestyle behaviour recommendations for nutrition, physical activity, screen time, and sleep were used to determine whether participants were meeting established guidelines. Overall, participants presented with poor lifestyle behaviours. Although most consumed adequate servings of grain products (93.9%) and meat and alternatives (68.7%), few met the serving recommendations for milk and alternatives (31.3%) or vegetables and fruit (14.1%). Physical activity levels were low – 7.4% and 4.1% achieved the recommended time and steps per day goals, respectively. Approximately 1/4 (22.7%) met the screen time recommendation, whereas fewer than 1/2 (47.4%) achieved the nightly sleep duration goal. Sex and age-group comparisons revealed subtle, but potentially important, differences in lifestyle behaviours that have implications for pediatric weight management. This study highlights the sub-optimal lifestyle behaviours of overweight children and adolescents referred for weight management. Intervention studies are needed to determine whether overweight boys and girls who achieve the lifestyle behaviour targets included in this study are able to successfully manage their weight and (or) reduce obesity-related health risks.
PPAR-γ-independent inhibitory effect of rosiglitazone on glucose synthesis in primary cultured rabbit kidney-cortex tubules
Authors: Derlacz Rafal A. , Hyc Karol , Usarek Michal , Jagielski Adam K. , Drozak Jakub , Jarzyna Robert 
Published: October 2008

Therapeutic effect of rosiglitazone has been reported to result from an improvement of insulin sensitivity and inhibition of glucose synthesis. As the latter process occurs in both liver and kidney cortex the aim of this study was to elucidate the rosiglitazone action on glucose formation in both tissues. Primary cultured cells of both liver and kidney cortex grown in defined medium were use throughout. To identify the mechanism responsible for drug-induced changes, intracellular gluconeogenic intermediates and enzyme activities were determined. In contrast to hepatocytes, the administration of a 10 µmol/L concentration of rosiglitazone to renal tubules resulted in about a 70% decrease in the rate of gluconeogenesis, accompanied by an ~75% decrease in alanine utilization and a 35% increase in lactate synthesis. The effect of rosiglitazone was not abolished by GW9662, the PPAR-γ irreversible antagonist, indicating that this action is not dependent on PPAR-γ activation. In view of rosiglitazone-induced changes in gluconeogenic intermediates and a diminished incorporation of14CO2into pyruvate, it is likely that the drug causes a decline in flux through pyruvate carboxylase and (or) phosphoenolpyruvate carboxykinase. It is likely that the hypoglycemic action of rosiglitazone is PPAR-γ independent and results mainly from its inhibitory effects on renal gluconeogenesis.
Specific dynamic action, apparent assimilation efficiency, and digestive rate in an arboreal pitviper,Trimeresurus stejnegeri stejnegeri
Authors: Tsai Tein-Shun , Lee How-Jing , Tu Ming-Chung 
Published: October 2008

The major aims of this study were to assess the effects of temperature (15–35 °C) and meal size (less than 30% snake mass) on the metabolism and digestive physiology of Trimeresurus stejnegeri stejnegeri Schmidt, 1925 and to compare the results with those of terrestrial snakes. Specific dynamic action (SDA), peak Vo2, and scope of peak Vo2increased with meal size. Temperature had little effect on SDA. With regression analysis, we found that baseline metabolic rates of T. s. stejnegeri were generally smaller than that for frequent feeders and larger than that for infrequent feeders. We generalized three types of SDA profiles among T. s. stejnegeri and terrestrial snakes (including frequent and infrequent feeders). Trimeresurus stejnegeri stejnegeri had a more shallow and extended profile of postprandial metabolism, which did not support our hypothesis that the pace of digestive metabolism of arboreal snakes is faster than that of terrestrial snakes. The apparent assimilation efficiency (range 0.698–0.884) was significantly lower at 15 °C. At the preferred temperature (26.5–28.8 °C) for a postprandial 50 g snake, the simulated ratios of four parameters (time to peak Vo2, first defecation time, gastric digestion time, and final defecation time) to SDA duration approximated 0.2, 0.5–0.7, 0.7, and 1.1, respectively.
Surviving on cached foods — the energetics of egg-caching by arctic foxes
Authors: Careau V. , Giroux J.-F. , Gauthier G. , Berteaux D. 
Published: October 2008

Food-caching by arctic foxes ( Vulpes lagopus (L., 1758)) is a behavioural adaptation thought to increase winter survival, especially in bird colonies where a large number of eggs can be cached during a short nesting season. In this paper, we measured the energy content of greater snow goose ( Chen caerulescens atlantica Kennard, 1927) eggs and evaluated their perishability when cached in tundra soil for a whole summer. We estimated that eggs lost only ~8% of their dry mass over 60 days of storage in the ground. We used published estimates on digestibility of nutrients by arctic foxes to estimate that fresh and stored goose eggs contained 816 and 730 kJ of metabolizable energy, respectively, a difference of 11%. Using information on arctic fox energetics, we evaluated that 145 stored eggs were required to sustain the growth of one pup from the age of 1 to 3 months (nutritional independence). Moreover, 23 stored eggs were energetically equivalent to the average fat deposit of an arctic fox during winter. Finally, we calculated that an adult arctic fox would need to recover 160–220 stored eggs to survive 6 months in resting conditions during cold winter temperatures. This value increased to 480 when considering activity cost. Based on egg acquisition and caching rates observed in many goose colonies, we conclude that cached eggs represent an important source of energy relative to the needs of an arctic fox during winter, and have thus a high fitness value.
Characterization of Acute Brain Injuries and Neurobehavioral Profiles in a Rabbit Model of Germinal Matrix Hemorrhage
Authors: Georgiadis Paraskevi , Xu Hongmin , Chua Caroline , Hu Furong , Collins Lee , Huynh Chau , LaGamma Edmund F. , Ballabh Praveen 
Published: October 2008

Background and Purpose—Germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH) is the most common neurological problem of premature infants and has enormous financial and social impact. Despite this, there is no standardized animal model of IVH depicting acute brain injuries.Methods—We delivered rabbit-pups prematurely at 29-day gestation by C-section, administered intraperitoneal glycerol to the pups at 3-hour postnatal age to induce IVH, and evaluated the brain for evidence of injuries.Results—About 80% of glycerol-treated pups developed gross IVH. We found greater neutrophil and microglia infiltration around the ventricles (periventricular zone) in pups with IVH than in controls. We noted more apoptosis and neuronal degeneration in the periventricular zone than in the neocortex in pups with IVH, but not in controls. There was evidence of axonal damage revealed by β-amyloid precursor protein and neurofilament immunolabeling. Neurobehavioral testing showed that pups with IVH were more wobbly with lesser capability to walk on inclination than pups without IVH. There was no evidence of acute systemic toxicity in the glycerol-treated pups. An evaluation of autopsy materials from premature infants revealed similar evidence of apoptosis and cellular infiltration in the periventricular zone in cases with IVH, but not in cases without IVH—suggesting clinical relevance of the model.Conclusion—The study provides an instructive animal model of IVH with evidence of acute brain injuries that can be used to evaluate strategies in prevention of IVH and acute posthemorrhagic complications.