摘要:

The electrically evoked contractile properties of the triceps surae and short-term ( < 2 s) maximal power output during vertical jumping have been examined before and after heating (by water immersion) in 5 elderly men aged 70 ± 5 years. Leg immersion in water at 44°C for 30 min produced a 3.4°C rise in muscle temperature (Tm) and was associated with a significant (p < 0.001) reduction in maximal time to peak tension and half relaxation time of the twitch, but was without affect on maximal twitch, tetanic (20 and 50 Hz) and voluntary tensions. However, at 10 Hz maximal tetanic tension was reduced (p < 0.05) from 604 ± 104 to 422 ± 142 N. During vertical jumping from a force platform, peak power output (W) was significantly (p < 0.05) increased from 1,155 ± 212 to 1,381 ± 307 W after heating. The rise in W was due to a small increase in both take-off velocity and the exerted force, and was reflected in a 3-cm increase in the height jumped from the force platform. It is concluded that the contractile characteristics of elderly triceps surae can be modified by heating and a rise in Tm does effect a change in the capacity of the muscle to generate

ISSN:0304-324X    

DOI:10.1159/000212675

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The body composition of 40 healthy elderly and 20 healthy young subjects was determined and compared. It was found that the age-related changes were more marked in females than in males. Total body water was decreased as a consequence of diminished lean body mass. Extracellular fluid volume remained unchanged, while plasma volume increased. Thus, the liquid components of lean body mass were redistributed between the intracellular and extracellular spaces. The elimination kinetics of isotopes were not significantly different between young and aged subjects, except the elimination of radiosulfate.

ISSN:0304-324X    

DOI:10.1159/000212676

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Reperfusion- and reoxygenation-induced ventricular tachyarrhythmias were studied on 6-month-old (adult) and 24-month-old (senescent) Langendoríf perfused rat hearts. The incidence of arrhythmias was significantly higher in the group of senescent hearts. Furthermore, the reperfusion- and reoxygenation-induced contracture was also more frequent in the group of senescent hearts. The interrelation between contracture and arrhythmias might represent an indirect evidence to suggest that alterations in cell calcium homeostasis have an important role in the origin of both phenomena and, possibly, in their increased incidence in the senescent heart

ISSN:0304-324X    

DOI:10.1159/000212677

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Human skin fibroblasts of about the same population doubling level, derived from donors of different age, were cloned. After 14 days of growth, the clones were morphologically classified, and cell counts were performed. Significant differences between the three age groups (infant, young adult, old adult) examined concerned the percentual clone type distribution. The size of a single clone depended on the clone type referring to the differentiation level of the cells in all age groups.

ISSN:0304-324X    

DOI:10.1159/000212678

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

T lymphocytes from healthy aged subjects were challenged with 12-O-tetradecanoylphorbol-13-acetate (TPA, a T-cell mitogen) in solid cultures and compared under the same experimental conditions to a group of younger controls. The aged cells showed diminished proliferation and incorporation of tritiated thymidine (3H-Tdr). However, when unfractionated peripheral blood mononuclear cells or isolated T cells from the aged individuals were cultured in the presence of 2-mercaptoethanol, autologous erythrocytes or co-cultured with a non-T cell fraction, an increased proliferative response was observed. Our results suggest that the reduction in proliferative capacity of aged T cells observed in liquid culture is also elicited in solid conditions. However, under appropriate signals a TPA-susceptible T-cell subpopulation may contribute significantly in enhancing their in vitro response. This in turn would suggest that age-related cellular changes are intrinsic in nature and not fully reversible with potentiating factors.

ISSN:0304-324X    

DOI:10.1159/000212679

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Mice were standardized to 12 h of light exposure alternating with 12 h of darkness and were fed ad libitum. The mice in the first group were 8 weeks old and in the other 104–116 weeks old. Subgroups of 7 animals from each age group were killed at 6 circadian stages. Enzyme activities of 23 enzymes from liver or brain were measured by an analysis of variance for each age group. All but 1 enzyme from young mice, and all but 9 from older mice showed significant changes over time (p < 0.01). The data from the 22 enzymes from young mice and the 14 enzymes from old mice were fit to the cosinor regression model to further characterize the rhythm. 15 enzymes from the young and 8 from the aged mice showed a significant regression to a 24-hour cosine curve (p < 0.01); of the 8, 7 were the same enzymes in both groups. Amplitude changes, where they could be compared from the cosinor data (7 enzymes), were not statistically different. When total variance was compared, 12 enzymes showed unequal variance. Of these, old mice had the larger variance in 9 enzymes. Another difference between the young and the old was changes in mean enzyme activities. 12 enzymes from aged mice had decreased mesors, 2 had increased mesors, and 9 were unchanged. In general, our data suggest that some enzyme activity rhythms were lost, others were altered and a few were not affected by aging. In the case of many enzymes, older mice have a diminished ability to synchronize to the light signal

ISSN:0304-324X    

DOI:10.1159/000212680

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Isometric exercise, promulgated as a test of autonomic function, has not been investigated in the elderly. Increasing age does not affect the cardiovascular responses to isometric exercise. Variability studies during fatiguing isometric exercise confirm that it is a valuable test of autonomic function in the elderly.

ISSN:0304-324X    

DOI:10.1159/000212681

出版商:S. Karger AG    

年代:1985

数据来源: Karger

ISSN:0304-324X    

DOI:10.1159/000212682

出版商:S. Karger AG    

年代:1985

数据来源: Karger