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We tested the hypothesis that the age-related decline in maximal aerobic capacity, as measured by maximal oxygen uptake (VO(2 max)), is greater in Hispanic than in Caucasian women. We studied 146 healthy sedentary women aged 20-75 yr: 53 Hispanic (primarily of Mexican descent) and 93 Caucasian (non-Hispanic white). The groups did not differ in mean age, body mass, percent body fat, estimated physical activity-related energy expenditure, or education-based socioeconomic status (SES). During maximal exercise, respiratory exchange ratio, rating of perceived exertion, and percent predicted maximal heart rate were similar across age and ethnicity, suggesting equivalent maximum voluntary efforts in all subjects. VO(2 max) (ml x kg(-1) x min(-1)) was inversely related to age (P < 0.01) in Caucasian (r =-0.68) and Hispanic (r = -0.61) women. The absolute rate of decline in VO(2 max) with age was the same in the two groups (-0.31 ml x kg(-1) x min(-1) x yr(-1)). The relative rate of decline (% from age 25 yr) also was similar in the Caucasian (-9.0%) and Hispanic (-9.2%) women. When subjects of all ages were pooled, mean levels of VO(2 max) were similar in the two groups (approximately 28 ml x kg(-1) x min(-1)). These results, the first to our knowledge in Hispanics, indicate that mean levels of VO(2 max), as well as the rate of decline in VO(2 max) with age, are similar in healthy sedentary Hispanic and Caucasian women of similar SES. Thus it does not appear that Hispanic ethnicity per se modulates maximal aerobic capacity in this population. 相似文献
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The nervous system of Tricladida. II. Neuroanatomy ofDugesia tigrina (Paludicola,Dugesiidae): An immunocytochemical study 总被引:2,自引:0,他引:2
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Tannert A Kurz A Erlemann KR Müller K Herrmann A Schiller J Töpfer-Petersen E Manjunath P Müller P 《European biophysics journal : EBJ》2007,36(4-5):461-475
The bovine seminal plasma protein PDC-109 modulates the maturation of bull sperm cells by removing lipids, mainly phosphatidylcholine
and cholesterol, from their cellular membrane. Here, we have characterized the process of extraction of endogenous phospholipids
and of their respective analogues. By measuring the PDC-109-mediated release of fluorescent phospholipid analogues from lipid
vesicles and from biological membranes (human erythrocytes, bovine epididymal sperm cells), we showed that PDC-109 extracts
phospholipids with a phosphorylcholine headgroup mainly from the outer leaflet of these membranes. The ability of PDC-109
to extract endogenous phospholipids from epididymal sperm cells was followed by mass spectrometry, which allowed us to characterize
the fatty acid pattern of the released lipids. From these cells, PDC-109 extracted phosphatidylcholine and sphingomyelin that
contained an enrichment of mono- and di-unsaturated fatty acids as well as short-chain and lyso-phosphatidylcholine species.
Based on the results, a model explaining the phospholipid specificity of PDC-109-mediated lipid release is presented.
Astrid Tannert and Anke Kurz have contributed equally to this work.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献
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Audet N Galés C Archer-Lahlou E Vallières M Schiller PW Bouvier M Pineyro G 《The Journal of biological chemistry》2008,283(22):15078-15088
Heptahelical receptors communicate extracellular information to the cytosolic compartment by binding an extensive variety of ligands. They do so through conformational changes that propagate to intracellular signaling partners as the receptor switches from a resting to an active conformation. This active state has been classically considered unique and responsible for regulation of all signaling pathways controlled by a receptor. However, recent functional studies have challenged this notion and called for a paradigm where receptors would exist in more than one signaling conformation. This study used bioluminescence resonance energy transfer assays in combination with ligands of different functional profiles to provide in vivo physical evidence of conformational diversity of delta-opioid receptors (DORs). DORs and alpha(i1)beta(1)gamma(2) G protein subunits were tagged with Luc or green fluorescent protein to produce bioluminescence resonance energy transfer pairs that allowed monitoring DOR-G protein interactions from different vantage points. Results showed that DORs and heterotrimeric G proteins formed a constitutive complex that underwent structural reorganization upon ligand binding. Conformational rearrangements could not be explained by a two-state model, supporting the idea that DORs adopt ligand-specific conformations. In addition, conformational diversity encoded by the receptor was conveyed to the interaction among heterotrimeric subunits. The existence of multiple active receptor states has implications for the way we conceive specificity of signal transduction. 相似文献
37.
Rotifer Nervous System Visualized by FMRFamide and 5-HT
Immunocytochemistry and Confocal Laser Scanning Microscopy 总被引:6,自引:4,他引:6
Elena?A.?Kotikova Olga?I.?Raikova Maria?ReuterEmail author Margaretha?K. S.?Gustafsson 《Hydrobiologia》2005,546(1):239-248
The characteristic ecology of floodplain lakes is in part due to their relatively strong water-level fluctuations. We analyzed the factors determining water-level fluctuations in 100 floodplain lakes (during non-flooded conditions) in the active floodplains of the Lower Rhine in the Netherlands. Furthermore, we explored the relationship between water-level fluctuations and macrophyte species richness, and analyzed the suitability of artificially created lakes for macrophyte vegetation. During non-flooded conditions along the Rhine, lake water-level fluctuations are largely driven by groundwater connection to the river. Hence, water-level fluctuations are largest in lakes close to the main channel in strongly fluctuating sectors of the river and smallest in isolated lakes. Additionally, water-level fluctuations are usually small in old lakes, mainly due to reduced groundwater hydraulic conductivity resulting from accumulated clay and silt on the bottom. Species richness of floating-leaved and emergent macrophytes was reduced at both small and large water-level fluctuations, whereas species richness of submerged macrophytes was reduced at small water-level fluctuations only. In addition, species richness of submerged macrophytes was higher in lakes that experienced drawdown, whereas no similar pattern was detected for floating-leaved and emergent macrophytes. The decline in amplitude of lake water-level with lake age implies that the number of hydrologically dynamic lakes will decrease over time. Therefore, we suggest that excavation of new lakes is essential to conserve the successional sequence of floodplain water bodies including conditions of high biodiversity. Shallow, moderately isolated, lakes with occasional bottom exposure have the highest potential for creating macrophyte-rich floodplain lakes along large lowland rivers. The water-level regime of such lakes can in part be designed, through choice of the location along the river, the distance away from the river and the depth profile of the lake. 相似文献
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