ISSN:0304-324X    

DOI:10.1159/000213168

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

To assess the effects of advanced age on the ability of circulating neutrophils to respond to biologically relevant chemoattractants, cells were isolated from the peripheral blood of pathogen and disease-free C57BL/6 mice and evaluated in a microchemotaxis chamber. The responses of granulocytes obtained from senescent mice (26–28 months) to the chemotactic peptide, FMLP, and to leukotriene B4 were similar to those found with cells from the younger animals (8–10 months). In contrast, the migration of neutrophils in response to sonicated type 3 Streptococcus pneumoniae was significantly greater with cells from the older animals. Similarly, the chemotactic response of neutrophils to zymosan-activated serum was greater with cells and serum from the senescent animals; however, the enhanced chemotaxis exhibited by granulocytes from the aged mice was a consequence of serum factors. Following the deposition of viable type 3 S. pneumoniae into the lower respiratory tract, the neutrophil influx at 24 h after challenge was significantly greater in the senescent mice; however, age-related differences in survival rates and LD50 were not detected. Thus, in the C57BL/6 mouse, senescence is not associated with deficiencies in the response of neutrophils in vitro to chemoattractants that contribute to lung host defense against the pneumococcus; further, in this murine strain, advanced age does not result in an attenuation of the pulmonary inflammatory reaction to infection with type 3 S. pneumoniae<

ISSN:0304-324X    

DOI:10.1159/000213169

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The present study was undertaken to understand the mechanism of alteration of the alloreactivity of T cells in aged mice. The experiment utilized bone marrow chimeras revealed that the age-associated changes in alloreactivity are not primarily determined by the bone marrow stem cells but determined by the environment where stem cells differentiate into mature T cells. The limiting dilution analysis and microfluorometry analysis indicated that the changes lie in both frequency of alloreactive T cells and the expression of T cell antigen receptor. Such quantitative and qualitative changes seem to be the causes for declined alloreactivity of T cells in aged mice.

ISSN:0304-324X    

DOI:10.1159/000213226

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Membrane potentials involved in neuronal excitability, transmitter uptake and so on were determined using synaptosomes from different age groups of mice. Synaptosomal resting membrane potential was found to decrease significantly in senescence. Concomi-tantly decreased activity of an electrogenic enzyme, Na+, K+-ATPase, was interpreted by two mechanisms. In senescence, the decreased content of phosphatidylcholine seemed responsible in part for decreased enzyme activity due to the modified lipid microenvironment. In the late stages of senescence, decreased enzyme content may rather cause reduction of enzyme activity, leading to a less negative set point of the membrane potential.

ISSN:0304-324X    

DOI:10.1159/000213228

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The degree of inhibition of hepatic succinic dehydrogenase activity by malonate, a competitive inhibitor, did not differ between young and middle-aged lizards. On the other hand, the same parameter increased significantly between middle-aged and old lizards. The percent inhibition of enzyme activity by p-chlorophenoxy acetic acid was also age-dependent, being higher in middle-aged and old than in young lizards.

ISSN:0304-324X    

DOI:10.1159/000213170

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The two antisera to paired helical filaments (PHF) and tau, which stained neu-rofibrillary tangles similarly in tissue section, were characterized. Anti-PHF reacted exclusively with the carboxyl terminal portion of tau, whereas antitau reacted with the amino terminal portion. In the blots of PHF prepared in Sarkosyl (Sarkosyl-PHF), anti-PHF stained an extensive smear from the top to the bottom of the gel, while antitau did not stain this kind of smear but labeled a small amount of intact tau that was bound to Sarkosyl-PHF. An LDS-or SDS-insoluble residue of Sarkosyl-PHF was labeled with anti-PHF, but not with antitau. Antitau-defined epitopes were susceptible to protease, whereas anti-PHF-defined epitopes were unaffected. Based on these observations, we conclude that Sarkosyl-PHF were composed largely of the carboxyl terminal region of tau and accompanied by a small amount of intact tau on their surfaces.

ISSN:0304-324X    

DOI:10.1159/000213229

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Taurine (TAU) is thought to be a neuromodulator or an inhibitory neurotrans-mitter in the mammalian brain. In the periphery, TAU is involved in a wide spectrum of physiological functions. One of the most important putative physiological function of TAU is the modulation of cardiovascular activity including blood pressure control. TAU also appears to be important for the development of an organism, especially early central nervous system development. Regional TAU content was measured in brains of adult (6-month) and aged (23- to 26-month) Fischer-344 (F-344) male rats. To assess the putative neurotransmit-ter role of TAU, release due to potassium depolarization was studied using slices from frontal cortex of F-344 rats. Circulating levels of TAU were also determined in male F-344 rats (6 and 24 months of age) and female Long-Evans rats (LE, 6 and 30 months old). We found no age-related change in TAU stores from the brain regions examined, nor did we find any indication of TAU release due to potassium depolarization in the release paradigm utilized. There was, however, a significant reduction (28 and 42%) in plasma TAU concentration in F-344 and LE rats, respectively. This age-related reduction in plasma TAU may have important consequences both peripherally and centrally with respect to regulation of blood pressure, cardiovascular function, and cardioprotection, as well as possible CNS complications.

ISSN:0304-324X    

DOI:10.1159/000213171

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Calcium-related factors were compared in 60 elderly female subjects, who were classified into three groups as nondementia group (n = 18), groups of senile dementia of Alzheimer type (SDAT, n = 22) and of vascular type (VTD, n = 20). The group of SDAT showed significant decrease in serum calcium, and increases in serum parathyroid hormone and urinary Ca, and tendency of decrease in serum 1,25-dihydroxyvitamin D, compared to those of the nondementia group. However, the group of VTD, without showing these features, showed a tendency towards decreased serum calcitonin. These results suggest that Ca and Ca-regulating hormones may play several important and different roles in senile dementia.

ISSN:0304-324X    

DOI:10.1159/000213230

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The age-dependent decrease of skin thickness was studied with a morphometric procedure on upper inner arm skin biopsies. Epidermal thickness decreased somewhat faster in men (7.2 % of the original value/decade) than in women (5.7 %). The total dermal thickness decreased at about the same rate in men and women (6%/decade). The thickness of the superficial layer of the dermis exhibited a biphasic evolution with age and these variations were not significantly different between men and women because of the large individual variations. This may be due partially to the difficulties of delineating with precision the limit between superficial and reticular dermis. These results are somewhat lower than those obtained by physical measurements of skin thickness. This may be due to fixation artifacts and also to the overestimation of skin thickness by physical measurements.

ISSN:0304-324X    

DOI:10.1159/000213172

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Possible roles for molecular genetical approaches to understand the pathogenesis of hypertension are briefly reviewed. To elucidate observed alterations in hypertensive subjects at both molecular and systemic levels in a comprehensive way, a model (a working hypothesis) for the molecular pathogenesis of hypertension is proposed. Prospects for identifying restriction fragment length polymorphisms observed in hypertensive rats but not in normotensive rats are also discussed.

ISSN:0304-324X    

DOI:10.1159/000213231

出版商:S. Karger AG    

年代:1990

数据来源: Karger