bluuebunny/crossref_metadata_2025 huggingface dataset:
Female boxers have high bone mineral density despite low body fat mass, high energy expenditure, and a high incidence of oligomenorrhea
Authors: Trutschnigg Barbara , Chong Chin , Habermayerova Lucia , Karelis Antony D. , Komorowski Joanna
Published: October 2008

Low body fat mass and menstrual irregularities have been associated with low bone mineral density (BMD). The aim of this study was to compare the relation between BMD, lean body mass, fat mass, physical activity energy expenditure (PAEE), and menstrual status in female boxers and in physically active females with low (C1) or average (C2) fat mass. Boxers (n = 11) and controls (C1, n = 16; C2, n = 17), aged 18–38 years, were assessed for BMD and body composition with dual-energy X-ray absorptiometry. Menstrual status and PAEE were determined from questionnaires. There was no difference in anthropometric measurements between boxers and C1 subjects, except that boxers had higher arm lean mass. However, both boxers and C1 subjects had a lower percentage of fat (p < 0.001) than C2 subjects (boxers, 14.6% ± 2.0; C1, 15.5% ± 4.2; C2, 25.8% ± 3.4%), and boxers had a higher (p = 0.002) lean body mass index (lean body mass/height2, where lean body mass is measured in kilograms and height is measured in metres) than C2 subjects. The PAEE of boxers was higher (p < 0.007) than that of controls (boxers, 5748 ± 2284 ; C1, 2966 ± 2258 ; C2, 2714 ± 1722 kcal·week–1). Oligomenorrhea was more common in boxers than in C1 and C2 subjects (boxers, 54.6%; C1, 18.8%; C2, 35.3%). Arm, leg, and spine BMD were higher (p < 0.008) in boxers than in C1 subjects, and arm BMD was higher in boxers than in C2 subjects. BMD Z scores were also higher (p < 0.05) in boxers (boxers, 1.1± 0.8, C1, 0.1 ± 0.7; C2: 0.3 ± 1.1). High BMD in boxers, despite low fat mass, high PAEE, and an increased incidence of oligomenorrhea suggest that boxing has a positive effect on BMD.
Effect of hyperthermia and physical activity on circulating growth hormone
Authors: Ftaiti Foued , Jemni Monem , Kacem Asma , Zaouali Monia Ajina , Tabka Zouhair , Zbidi Abdelkarim , Grélot Laurent
Published: October 2008

The aim of this study was to differentiate the effects of hyperthermia and physical activity on circulating growth hormone (GH) secretion. Nine healthy volunteer adults performed two 40 min exercise trials and two 50 min passive standing trials. The exercise was performed in either thermo-neutral (N-Ex: air temperature 18 °C, air humidity 40%, and wet bulb globe temperature (WBGT) 17.7 °C) or hot environmental conditions (H-Ex: air temperature 33 °C, air humidity 30%, and WBGT 34.6 °C). The passive exposure trials were also performed in either a comfortable (N-P: air temperature 18 °C, air humidity 40%, and WBGT 17.7 °C) or a hot climatic chamber (H-P: air temperature 40 °C, air humidity 100%, and WBGT 97.1 °C). Plasma GH, plasma volume (PV), tympanic temperature (Tty), and body mass loss (BML) were measured before and after each trial. The decrease in PV was significantly higher during H-Ex and H-P sessions than during N-Ex and N-P sessions. Comparisons showed significantly lower BML in the N-Ex session (1.5% ± 0.3%) than in the H-Ex and H-P sessions (2.1% ± 0.3% and 1.9% ± 0.2%, respectively) (p < 0.001). The rise in Tty was significantly higher during the H-P session (2.9 ± 0.4 °C) (p < 0.001) when compared with the other sessions. Plasma GH concentration increased significantly during all the trials, particularly during the H-Ex session (45 ± 7 ng·mL–1) (p < 0.01). Both exercise and heat exposure, separately, are sufficient to increase significantly the plasma GH concentration, and their combined effect induced a highly synergistic rise in GH.
A practical and precise approach to quantification of body composition in cancer patients using computed tomography images acquired during routine care
Authors: Mourtzakis Marina , Prado Carla M.M. , Lieffers Jessica R. , Reiman Tony , McCargar Linda J. , Baracos Vickie E.
Published: October 2008

Human body composition is important in numerous cancer research domains. Our objective was to evaluate clinically accessible methods to achieve practical and precise measures of body composition in cancer patients. Dual-energy X-ray absorptiometry (DXA)-based analysis of fat and fat-free mass was performed in 50 cancer patients and compared with bioelectrical impedance analysis (BIA) and with regional computed tomography (CT) images available in the patients’ medical records. BIA overestimated or underestimated fat-free mass substantially compared with DXA as the method of reference (up to 9.3 kg difference). Significant changes in fat-free mass over time detected with DXA in a subset of 21 patients (+2.2 ± 3.2%/100 days, p = 0.003), was beyond the limits of detection of BIA. Regional analysis of fat and fat-free tissue at the 3rd lumbar vertebra with either DXA or CT strongly predicted whole-body fat and fat-free mass (r = 0.86–0.94; p < 0.001). CT images provided detail on specific muscles, adipose tissues and organs, not provided by DXA or BIA. CT presents great practical significance due to the prevalence of these images in patient diagnosis and follow-up, thus marrying clinical accessibility with high precision to quantify specific tissues and to predict whole-body composition.
Knowledge of carbohydrate consumption does not alter natural killer cell activity following an acute bout of high-intensity aerobic exercise
Authors: McFarlin Brian K. , Hutchison Alexander T. , Kueht Michael L.
Published: October 2008

Carbohydrate consumption during strenuous aerobic exercise reportedly minimizes post-exercise suppression of the innate immune system. One of the most common measurements of innate immunity is natural killer cell activity (NKCA). It is not known whether actual carbohydrate consumption or merely the knowledge of carbohydrate consumption mediates alteration in NKCA. The purpose of the present investigation was to determine if knowledge of carbohydrate beverage could result in alteration of RPE and NKCA, independent of actual carbohydrate intake. We recruited 11 male and female endurance athletes and randomly assigned them to either a correct or false knowledge of carbohydrate intake, such that in the false group, subjects were informed that they were receiving the carbohydrate beverage (CHO), but actually received a placebo (PLA) beverage. CHO and PLA beverages were matched to be similar in taste and appearance. Subjects completed 60 min of cycle ergometry (74% of VO2 peak). Venous blood samples were collected before (PRE), immediately after (POST), and 2 h after (2H) exercise and used to determine plasma glucose concentration, leukocyte total and differential counts, and NKCA. Data were statistically analyzed using a 3-factor analysis of variance (ANOVA) (p < 0.05). We did not find a significant effect of knowledge of drink type on leukocyte count, leukocyte differential, or NKCA. Drink type did not significantly alter leukocyte total, differential counts, or NKCA. There was a significant effect of exercise on NKCA. Knowledge of drink type does not alter innate immunity following exercise as assessed by leukocyte counts and NKCA.
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.
The exercise-induced stress response in skeletal muscle: failure during aging
Authors: Kayani Anna C. , Morton James P. , McArdle Anne
Published: October 2008

Mammalian adult skeletal muscle adapts to the stress of contractile activity with increased gene expression by yielding a family of highly conserved cytoprotective proteins known as heat shock proteins (HSPs). Although the exercise-induced stress response of both animal and human skeletal muscle is now well documented, the precise mechanisms underlying this adaptation remain unclear. The induction of HSPs after exercise is severely blunted in the muscle of older individuals. This review focuses on the effects of different forms of exercise and training on the induction of HSPs in the muscles of adult individuals, and examines the proposed mechanisms underlying this adaptation. Furthermore, the functional effect of the inability of the muscles of older individuals to adapt in this way is discussed, together with the proposed mechanisms underlying this maladaptation.
Anti-invasive effect of gambogic acid in MDA-MB-231 human breast carcinoma cells
Authors: Qi Qi , Lu Na , Wang Xiao-tang , Gu Hong-yan , Yang Yong , Liu Wei , Li Chenglin , You Qi-dong , Guo Qing-long
Published: October 2008

Gambogic acid (GA) has been known to have antitumor activity in vitro and in vivo. In the present study, we investigated the anti-invasive effects of GA in MDA-MB-231 human breast carcinoma cells. The results indicated that GA significantly inhibited the adhesion, migration, and invasion of the cells in vitro tested by the heterotypic adhesion assay, wound migration assay, and chamber invasion assay. Results of Western blotting and immunocytochemistry analysis showed that GA could suppress the expressions of matrix metalloproteinase 2 (MMP-2) and 9 (MMP-9) in MDA-MB-231 cells. Furthermore, gelatin zymography revealed that GA decreased the activities of MMP-2 and MMP-9. Additionally, GA exerted an inhibitory effect on the phosphorylation of ERK1/2 and JNK, while it had no effect on p38. Taken together, our results demonstrated the anti-invasive property of GA for the first time and indicated it could serve as a promising drug for the treatment of cancer metastasis.
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.
Neuroregenerative strategies in the brain: emerging significance of bone morphogenetic protein 7 (BMP7)
Authors: Bani-Yaghoub Mahmud , Tremblay Roger G. , Ajji Abdellah , Nzau Munyao , Gangaraju Sandhya , Chitty David , Zurakowski Bogdan , Sikorska Marianna
Published: October 2008

Every year thousands of people suffer from brain injuries and stroke, and develop motor, sensory, and cognitive problems as a result of neuronal loss in the brain. Unfortunately, the damaged brain has a limited ability to enact repair and current modes of treatment are not sufficient to offset the damage. An extensive list of growth factors, neurotrophic factors, cytokines, and drugs has been explored as potential therapies. However, only a limited number of them may actually have the potential to effectively offset the brain injury or stroke-related problems. One of the treatments considered for future brain repair is bone morphogenetic protein 7 (BMP7), a factor currently used in patients to treat non-neurological diseases. The clinical application of BMP7 is based on its neuroprotective role in stroke animal models. This paper reviews the current approaches considered for brain repair and discusses the novel convergent strategies by which BMP7 potentially can induce neuroregeneration.
The regulation of the cardiac potassium channel (HERG) by caveolin-1
Authors: Lin Jijin , Lin Shuguang , Choy Patrick C. , Shen Xiuzhang , Deng Chunyu , Kuang Sujuan , Wu Jun , Xu Wencan
Published: October 2008

Protein–protein interaction plays a key role in the regulation of biological processes. The human potassium (HERG) channel is encoded by the ether-à-go-go-related gene (herg), and its activity may be regulated by association with other cellular proteins. To identify cellular proteins that might play a role in the regulation of the HERG channel, we screened a human heart cDNA library with the N terminus of HERG using a yeast 2-hybrid system, and identified caveolin-1 as a potential HERG partner. The interaction between these 2 proteins was confirmed by coimmunoprecipitation assay, and their overlapping subcellular localization was demonstrated by fluorescence immunocytochemistry. The physiologic implication of the protein–protein interaction was studied in whole-cell patch-clamp electrophysiology experiments. A significant increase in HERG current amplitude and a faster deactivation of tail current were observed in HEK293/HERG cells in a membrane lipid rafts disruption model and caveolin-1 knocked down cells by RNA interference. Alternatively, when caveolin-1 was overexpressed, the HERG current amplitude was significantly reduced and the tail current was deactivated more slowly. Taken together, these data indicate that HERG channels interact with caveolin-1 and are negatively regulated by this interaction. The finding from this study clearly demonstrates the regulatory role of caveolin-1 on HERG channels, and may help to understand biochemical events leading to arrhythmogenesis in the long QT syndrome in cardiac patients.
Iron regulatory protein 1 is not an early target of cadmium toxicity in mice, but it is sensitive to cadmium stress in a human epithelial cell line
Authors: Rousselet Estelle , Moulis Jean-Marc
Published: October 2008

Disruption of iron homeostasis at the levels of intestinal absorption or erythropoiesis contributes to cadmium toxicity. Cellular iron homeostasis in metazoans is maintained by the iron regulatory proteins (IRPs) that regulate the synthesis of proteins involved in the transport, use, and storage of iron. The effect of cadmium intoxication on this regulatory system has been investigated in a cellular model of human epithelium. Cadmium exposure of HeLa cells did not activate the IRPs; rather, the amount of these proteins relative to that of housekeeping proteins decreased. Accordingly, the transferrin receptor mRNA level decreased upon cadmium insult. In a more integrated investigation, separate groups of mice had free access to different doses of cadmium in drinking water for 3 weeks. Cadmium accumulated in all analyzed organs, but its concentration in mouse tissues did not correlate with changes of the activity of the IRPs. The intoxicated mice did not show any sign of anemia, indicating that iron homeostasis was not immediately disrupted after the onset of cadmium accumulation. These data establish that cadmium destabilizes IRPs in mammalian cells, but that iron imbalance is not an early event of cadmium intoxication.
In situ calcium mapping in the mouse retina via time-of-flight secondary ion mass spectrometry: modulation of retinal angiogenesis by calcium ion in development and oxygen-induced retinopathy
Authors: Kim Jeong Hun , Kim Jin Hyoung , Yu Young Suk , Kim Dong Hun , Lee Tae Geol , Won Moon Dae , Kim Kyu-Won
Published: October 2008

Pathological angiogenesis in the eye is the most common cause of blindness in all age groups. In physiological and pathological cellular processes including angiogenesis, ion homeostasis is greatly affected. This study is to investigate the role of calcium ion in physiological and pathological angiogenesis in the retina, which is based on the results of ion mapping by time-of-flight secondary ion mass spectrometry (TOF-SIMS). We provided that calcium distribution is the most accordant to change with physiological vessel formation of development in the retina and pathological angiogenesis of oxygen-induced retinopathy (OIR), which is supported by ion mapping in retinal tissue using TOF-SIMS. In addition to anti-proliferative and anti-angiogenic activity of the calcium inhibitor on endothelial cells, retinal neovascularization of OIR was effectively inhibited by the calcium inhibitor. Calcium ion could play a crucial role in physiological and pathological angiogenesis in the retina. Moreover, TOF-SIMS could be a good method to simultaneously evaluate the changes of variable ions of the retina in biological processes.
The 1946 Mount Colonel Foster rock avalanche and associated displacement wave, Vancouver Island, British Columbia
Authors: Evans Stephen G.
Published: October 2008

The 1946 Vancouver Island earthquake (M = 7.2) triggered a rock avalanche from the north face of Mount Colonel Foster, central Vancouver Island, British Columbia. Approximately 1.5 × 106 m3 of Triassic volcaniclastic rocks detached from between el. 1965 m and el. 1600 m. Although just over half of this volume was deposited in the upper part of the track above el. 1080 m, approximately 0.7 × 106 m3 descended the lower part of the track and entered the waters of Landslide Lake at el. 890 m. The resultant displacement wave ran up a maximum vertical distance of 51 m on the opposite shore and the wave crest was about 29 m high when it spilled over the lip of the lake. Water displaced during the event destroyed forest in the upper reaches of the Elk River valley up to 3 km from Landslide Lake. The wave at Landslide Lake is comparable to other waves generated by similar magnitude rock avalanches in Peru and Norway and it is the largest recorded in the Canadian Cordillera. The case history illustrates the conditions where substantial damage may be caused by a rock avalanche well beyond the limits of its debris when it produces a landslide-generated wave in the mountainous terrain of the Cordillera. Key words: rock avalanche, earthquake-induced landslides, landslide-generated waves, mountains.
An experimental study of a footing located on a sloped fill: influence of a soil reinforcement layer
Authors: Selvadurai A. P. S. , Gnanendran C. T.
Published: October 2008

This paper summarizes the results of a series of experimental investigations conducted to determine the manner in which the performance of a footing located at the crest of a sloped fill can be influenced by the presence of a reinforcing layer within the body of the fill. The results of these investigations indicate that both the load–settlement behaviour and the ultimate capacity of the footing can be enhanced by the presence of the reinforcing layer and that such efficiencies are derived for specific depths of embedment of the reinforcing layer. Key words: footings, reinforced slopes, ultimate capacity, load–displacement behaviour, failure modes.
Analysis of the earthquakes associated with the 1965 Hope landslide and their effects on slope stability at the site
Authors: Wetmiller R. J. , Evans S. G.
Published: October 2008

Two small earthquakes (M 3.2 and 3.1) associated with the Hope Slide of January 9, 1965, Canada's largest known historical landslide, have been reanalyzed using original seismograph records. The earthquakes were nearly identical events having similar epicentres, focal depths, magnitudes, and mechanisms and occurred no more than 30 km from the slide site. The revised epicentre calculated for both earthquakes was 49.36°N, 121.14°W with an uncertainty of about ±20 km. The new epicentre should be used in preference to the epicentres given for these events in the 1965 Canadian Earthquakes Catalogue and the 1965 International Seismological Centre Bulletin, which are both based on analysis of separate parts of the complete data set.The effect of the seismic accelerations on slope stability was considered and showed that a seismic trigger of the slide was feasible for either earthquake if it had a shallow focal depth and was located no more than about 10 km from the site, but the validity of a seismic trigger could not be confirmed because of the poor quality of the earthquake location. Local observations on the day of the slide show that the slide did not occur at the time of the first earthquake at 03:56 PST but that it may have occurred during the second earthquake at 06:58 PST. The slide mass was strongly shaken by other earthquakes in the region in 1872, 1946, and 1949 and must have had significantly more shear strength at those times than it did in 1965. The prime factor leading to the 1965 Hope Slide thus appears to have been a loss of shear strength in the slide mass sometime after 1949 putting the mass in a state of near-limiting equilibrium by January, 1965. Key words: earthquakes, landslides, seismic trigger.
Effects of intervening media on dielectrophoretic strengthening of soft clays
Authors: Lo K.Y. , Shang J.Q.
Published: October 2008

The process of dielectrophoresis has been shown to be applicable for soil improvement. This paper presents the results of continuous investigation into factors affecting dielectrophoretic strengthening of soft clays. The discussion is focused on the configuration of nonuniform electric fields, which is one of the key factors for effectiveness of dielectrophoretic treatment. The distribution of an ideal cylindrical electric field is derived and analyzed in light of the influence of intervening media in the space between electrode and soil. A series of dielectrophoretic experiments are conducted on a soft, sensitive natural clay to investigate the effects of intervening media and to examine the theory. The results indicate that the increase in undrained shear strength and decrease in soil water content after a dielectrophoretic treatment are dominated by the type and water content of intervening media. By minimizing the space between soil and electrode and adapting a clay slurry of relatively low water contents as the medium, the process of dielectrophoretic strengthening can be enhanced. Key words : soil improvement, dielectrophoresis, electrokinetic techniques, sensitive clays, electric field.
Quantitative determination of potential distribution in Stern–Gouy double-layer model
Authors: Shang J.Q. , Lo K.Y. , Quigley R.M.
Published: October 2008

A quantitative determination of the potential distribution in the Stern–Gouy double-layer model for clay–water–electrolyte systems is presented. The surface potential, Stern potential, thickness of the Gouy diffuse layer, and distribution of electrical potential can be computed by knowing the required parameters, such as the cation exchange capacity, specific surface area, electrolyte concentration, and valence, temperature, and permittivity of the solvent (pore fluid). The factors influencing the potential distribution in the double layer are discussed. To demonstrate the applications of the Stern–Gouy model, two examples are presented. In the first example, the relationship between the double-layer thicknesses and hydraulic conductivities of a natural soil permeated by different organic compounds is established. In the second example, the electric potential distributions of three natural clays are presented. It is anticipated that the Stern–Gouy double-layer model will find broader applications in geotechnical and environmental engineering practice as the principles and computation methods become more familiar to engineers. Key words : Stern–Gouy electrical double layer, clay–water–electrolyte systems, soil behaviour, hydraulic conductivity, sensitivity.
Ultimate pullout resistance of groups of vertical anchors
Authors: Hanna Adel , Ghaly Ashraf
Published: October 2008

A theoretical investigation on the group action of vertical screw anchors installed in sands is presented. An experimentally observed rupture surface for single anchors was employed to establish the shape of the rupture surface for groups of anchors. A theory was developed to predict the uplift capacity of groups of anchors with different configurations utilizing the theoretical model described in a companion paper. To calculate the uplift capacity, weight and shear factors for shallow and deep groups of anchors are established. These factors are presented as functions of the angle of shearing resistance of the sand, relative depth ratio of an individual anchor within the group, and (or) the ratio between the height of embedded failure bulb and anchor diameter. The effect of overconsolidation due to the compaction technique used in placing the sand was incorporated in the theoretical calculations of uplift capacity. Comparison between theoretical and experimental results shows good agreement in the case of loose and medium sands and satisfactory agreement in the case of dense sand. An empirical equation, based on theory and experimental data, is proposed to mathematically quantify the effect of densification-on the angle of shearing resistance of the sand. Key words : anchors, group action, limit equilibrium, overconsolidation ratio, theoretical analysis, uplift capacity.
A simple design for hydraulic consolidometer and volume gauge
Authors: Khan Mahbubul A. , Garga Vinod K.
Published: October 2008

This technical note describes the use of nitrile U-cup seals to simplify and improve the design of a hydraulic consolidometer and automatic volume gauge. The new devices are inexpensive and easy to fabricate and can readily be connected to a computerized data acquisition and control system. Key words : hydraulic consolidometer, volume gauge, bellofram seal, laboratory testing, U-cup seal.
Modelling unanticipated pore-water pressures in soft clays
Authors: Yin Jianhua , Graham James , Clark Jack I. , Gao Longjun
Published: October 2008

Field observations in thin soft clay layers may show pore-water pressures that increase for some time after the loading is applied. Reasons for these observations are not well understood. The paper shows how an elastic viscoplastic constitutive model incorporated into the consolidation equation can predict these pore-water pressure increases in soils that exhibit significant creep behaviour (or secondary compression). The phenomenon has been related to relaxation in regions of the profile from which drainage has not yet begun. Key words : clay, consolidation, creep, secondary compression, viscous, relaxation, pore-water pressure, elastic–plastic.
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.
Female-limited polymorphism in a widespread damselfly: morph frequencies, male density, and phenotypic similarity of andromorphs to males
Authors: Van Gossum H. , Robb T. , Forbes M. R. , Rasmussen L.
Published: October 2008

In several animal species, one male type coexists with two to several female types, a polymorphism often explained in the context of sexual selection. Where it occurs, one female morph typically resembles the conspecific male phenotype, but the degree of resemblance varies across species. Here, we question whether the degree of phenotypic similarity between male-like females and males varies within species. Phenotypic resemblance is hypothesized to depend on the potential for frequency- and density-dependent selection on male and (or) female phenotypes. We studied six populations of the damselfly Nehalennia irene (Hagen, 1861) that differed widely in estimates of morph frequency and male density. Male-like females resemble males more than another female type resembles males, across populations, when comparisons are based on abdominal patterns. Abdomen phenotype does matter in male–female interactions of damselflies. Furthermore, male-like females were more similar to males at low and high density sites compared with sites with intermediate densities, contrary to the hypothesis that the potential for male harassment influences the degree of phenotypic similarity. Additionally, male-like females of most populations converged on the abdominal phenotype of males of one population rather than on that of syntopic males; a problem that has not received any attention.
An overview and comparative analysis of singing on the nest in North American birds
Authors: Leonard M.
Published: October 2008

Bird song is used to defend territories and attract mates and tends to make the singer conspicuous. Singing on the nest (SOTN) has been mentioned since 1904 but has remained largely unexplored. This behavior occurs in 10.1% of breeding birds of North America. Factors that predict the likelihood of SOTN for any species include colonial nesting, incubation sharing and feeding, and taxonomic family. If SOTN is as conspicuous as other forms of singing, this behavior may incur significant costs, such as increased nest predation and parasitism. Data collected from the literature regarding nest vocalizations of adult birds (calls and songs) showed those costs were not significantly different between vocalizing and silent birds. There was greater variance in the rates of nest predation and parasitism for vocalizing birds, which may suggest greater risk. The function(s) of SOTN are not well understood and are mostly untested. Several hypotheses are presented to explain this behavior. This is the first attempt to examine this behavior in any depth and demonstrates the need for further research to explore its function(s) and consequences.
Effects of timing of nest entry and body size on the fertilization success of alternative male reproductive phenotypes of masu salmon (Oncorhynchus masou)
Authors: Watanabe M. , Takamura S. , Maekawa K.
Published: October 2008

Using a natural population of masu salmon ( Oncorhynchus masou (Brevoort, 1856)) in a stream of Shikaribetsu Lake, Hokkaido, Japan, we combined behavioural observations with genetic parentage analysis to explore the factors affecting fertilization success achieved by alternative mating tactics (fighting by large migratory males and sneaking by small mature male parr). Larger males gained priority access to females; migrant males do this by holding a guarding position near the nesting female and mature male parr do this by adopting sneaker behaviour and attending spawning groups. Status of mature male parr was related to success of nest entry but not to timing of nest entry, although the timing of nest entry influenced fertilization success of sneakers and ejaculation simultaneous with pair spawning was needed for fertilization by sneakers. The relative body size of each male who successfully spawned with a female is also likely to determine the proportion of eggs he fertilized because larger males have larger ejaculate. These results provide insight into factors relating to variation in fertilization success, how body size dimorphisms may be related to fitness, and evolution of alternative mating tactics.