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排序方式: 共有68条查询结果,搜索用时 15 毫秒
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2.
Testosterone, and winning and losing in human competition 总被引:9,自引:4,他引:5
Alan Booth Greg Shelley Allan Mazur Gerry Tharp Roger Kittok 《Hormones and behavior》1989,23(4):556-571
Testosterone and cortisol were measured in six university tennis players across six matches during their varsity season. Testosterone rose just before most matches, and players with the highest prematch testosterone had the most positive improvement in mood before their matches. After matches, mean testosterone rose for winners relative to losers, especially for winners with very positive moods after their victories and who evaluated their own performance highly. Winners with rising testosterone had higher testosterone before their next match, in contrast to losers with falling testosterone, who had lower testosterone before their next match. Cortisol was not related to winning or losing, but it was related to seed (top players having low cortisol), and cortisol generally declined as the season progressed. These results are consistent with a biosocial theory of status. 相似文献
3.
Terry J. Housh Herbert A. deVries Glen O. Johnson Sharon A. Evans Gerald D. Tharp Dona J. Housh Rommie J. Hughes 《European journal of applied physiology and occupational physiology》1990,60(5):391-394
The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT. 相似文献
4.
5.
Tharp WG Lee YH Maple RL Pratley RE 《Biochemical and biophysical research communications》2008,372(4):595-600
Antagonists of cannabinoid CB1 receptor (CB1, CNR1) promote weight loss and decrease hyperglycemia in patients with type 2 diabetes. While the endocannabinoid system may modulate islet hormone secretion, the cell-type expressing CB1 receptor in islets has not been fully resolved. In this study, we verified receptor gene expression in rodent islets and cell lines and examined the distribution of CB1 receptor in mouse, rat, and human islets by confocal immunofluorescence (IF) microscopy. IF demonstrated CB1 receptor was present in β-cell lines, but co-localized solely with somatostatin in the islet δ-cells of Zucker rats, C57BL/6 mice, and humans; no CB1 receptor expression was observed in α-, β-, or pp-cells. Similarly, a rat somatostatinoma cell line, MSL-G2-Tu6, was found to express CB1 receptor. We also found monoacylglycerol lipase (MAGL) to be expressed in δ-cells and fatty acid amide hydrolase (FAAH) to be expressed in α-cells. The specific expression of CB1 in δ-cells suggests that the ECS may play a role in modulating islet hormone secretion. As there are some differences between our findings and previous reports, further studies, including detailed physiological studies of the effects of the ECS on islet function, are warranted. 相似文献
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7.
Numerous transposed sequences of mitochondrial cytochrome oxidase I-II in aphids of the genus Sitobion (Hemiptera: Aphididae) 总被引:4,自引:1,他引:3
Polymerase chain reaction (PCR) products corresponding to 803 bp of the
cytochrome oxidase subunits I and II region of mitochondrial DNA (mtDNA
COI-II) were deduced to consist of multiple haplotypes in three Sitobion
species. We investigated the molecular basis of these observations. PCR
products were cloned, and six clones from one individual per species were
sequenced. In each individual, one sequence was found commonly, but also
two or three divergent sequences were seen. The divergent sequences were
shown to be nonmitochondrial by sequencing from purified mtDNA and Southern
blotting experiments. All seven nonmitochondrial clones sequenced to
completion were unique. Nonmitochondrial sequences have a high proportion
of unique sites, and very few characters are shared between
nonmitochondrial clones to the exclusion of mtDNA. From these data, we
infer that fragments of mtDNA have been transposed separately (probably
into aphid chromosomes), at a frequency only known to be equalled in
humans. The transposition phenomenon appears to occur infrequently or not
at all in closely related genera and other aphids investigated. Patterns of
nucleotide substitution in mtDNA inferred over a parsimony tree are very
different from those in transposed sequences. Compared with mtDNA,
nonmitochondrial sequences have less codon position bias, more even
exchanges between A, G, C and T, and a higher proportion of nonsynonymous
replacements. Although these data are consistent with the transposed
sequences being under less constraint than mtDNA, changes in the
nonmitochondrial sequences are not random: there remains significant
position bias, and probable excesses of synonymous replacements and of
conservative inferred amino acid replacements. We conclude that a
proportion of the inferred change in the nonmitochondrial sequences
occurred before transposition. We believe that Sitobion aphids (and other
species exhibiting mtDNA transposition) may be important for studying the
molecular evolution of mtDNA and pseudogenes. However, our data highlight
the need to establish the true evolutionary relationships between sequences
in comparative investigations.
相似文献
8.
9.
Bowles DK Maddali KK Ganjam VK Rubin LJ Tharp DL Turk JR Heaps CL 《American journal of physiology. Heart and circulatory physiology》2004,287(5):H2091-H2098
Evidence indicates that gender and sex hormonal status influence cardiovascular physiology and pathophysiology. We recently demonstrated increased L-type voltage-gated Ca2+ current (ICa,L) in coronary arterial smooth muscle (CASM) of male compared with female swine. The promoter region of the L-type voltage-gated Ca2+ channel (VGCC) (Cav1.2) gene contains a hormone response element that is activated by testosterone. Thus the purpose of the present study was to determine whether endogenous testosterone regulates CASM ICa,L through regulation of VGCC expression and activity. Sexually mature male and female Yucatan swine (7-8 mo; 35-45 kg) were obtained from the breeder. Males were left intact (IM, n=8), castrated (CM, n=8), or castrated with testosterone replacement (CMT, n=8; 10 mg/day Androgel). Females remained gonad intact (n=8). In right coronary arteries, both Cav1.2 mRNA and protein were greater in IM compared with intact females. Cav1.2 mRNA and protein were reduced in CM compared with IM and restored in CMT. In isolated CASM, both peak and steady-state ICa were reduced in CM compared with IM and restored in CMT. In males, a linear relationship was found between serum testosterone levels and ICa. In vitro, both testosterone and the nonaromatizable androgen, dihydrotestosterone, increased Cav1.2 expression. Furthermore, this effect was blocked by the androgen receptor antagonist cyproterone. We conclude that endogenous testosterone is a primary regulator of Cav1.2 expression and activity in coronary arteries of males. 相似文献
10.
Migration of antigen-specific T cells away from CXCR4-binding human immunodeficiency virus type 1 gp120 下载免费PDF全文
Brainard DM Tharp WG Granado E Miller N Trocha AK Ren XH Conrad B Terwilliger EF Wyatt R Walker BD Poznansky MC 《Journal of virology》2004,78(10):5184-5193
Cell-mediated immunity depends in part on appropriate migration and localization of cytotoxic T lymphocytes (CTL), a process regulated by chemokines and adhesion molecules. Many viruses, including human immunodeficiency virus type 1 (HIV-1), encode chemotactically active proteins, suggesting that dysregulation of immune cell trafficking may be a strategy for immune evasion. HIV-1 gp120, a retroviral envelope protein, has been shown to act as a T-cell chemoattractant via binding to the chemokine receptor and HIV-1 coreceptor CXCR4. We have previously shown that T cells move away from the chemokine stromal cell-derived factor 1 (SDF-1) in a concentration-dependent and CXCR4 receptor-mediated manner. Here, we demonstrate that CXCR4-binding HIV-1 X4 gp120 causes the movement of T cells, including HIV-specific CTL, away from high concentrations of the viral protein. This migratory response is CD4 independent and inhibited by anti-CXCR4 antibodies and pertussis toxin. Additionally, the expression of X4 gp120 by target cells reduces CTL efficacy in an in vitro system designed to account for the effect of cell migration on the ability of CTL to kill their target cells. Recombinant X4 gp120 also significantly reduced antigen-specific T-cell infiltration at a site of antigen challenge in vivo. The repellant activity of HIV-1 gp120 on immune cells in vitro and in vivo was shown to be dependent on the V2 and V3 loops of HIV-1 gp120. These data suggest that the active movement of T cells away from CXCR4-binding HIV-1 gp120, which we previously termed fugetaxis, may provide a novel mechanism by which HIV-1 evades challenge by immune effector cells in vivo. 相似文献