摘要:

An age-dependent effect on the ability to produce cyclic AMP in response to parathyroid hormone (PTH) stimulation was examined using culture skin fibroblasts from both young and elderly female subjects. The mean values of both absolute and comparative production of intracellular cyclic AMP due to various concentrations of PTH administration did not differ between the two age groups, although the mean serum PTH level was significantly higher in the elderly subjects. These results indicate that the decreased response of the target organ to PTH in aged subjects can be explained mainly by the decreased number of intact cells rather than a decreased response of individual cells to PTH.

ISSN:0304-324X    

DOI:10.1159/000213208

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Spontaneous activity level was measured in rotifers of the species Asplanchna brightwelli on each day of their 5-day life span. No correlation was seen in group data between activity level and life span. However, data from individuals showed a positive correlation between life span and activity level in the latter half of the life span on 3 days out of 5. This tendency toward greater activity in the longer-lived rotifers is not consistent with the rate of living theory of aging.

ISSN:0304-324X    

DOI:10.1159/000213209

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The hepatic glucose uptake of male garden lizards did not change during maturation but showed a decline between middle-aged and old age groups. The decline in glucose uptake following starvation and cold stress was age-dependent, the young and middle-aged lizards being more responsive than the old counterparts.

ISSN:0304-324X    

DOI:10.1159/000213210

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Sera from the elderly, but not young, inhibited markedly interleukin 2 (IL-2)-dependent proliferation of cloned T cells. Sera of aged humans contained high levels of tri-glyceride, cholesterol, very low density lipoproteins (VLDL) and low density lipoproteins (LDL). VLDL and LDL inhibited the proliferation in a dose-related manner. The inhibition correlated with levels of serum VLDL and LDL. These results suggest that lipoproteins may act as a regulator of IL-2-dependent proliferation and that disturbance of lipid and lipoprotein metabolism may be partially responsible for diminished immune responses in the elderly.

ISSN:0304-324X    

DOI:10.1159/000213211

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

In the present study we describe an original semi-automated image analysis method to quantitate the changes of the geometric properties of cutaneous microrelief with age. The skin surface is composed of very fine lines intersecting each other and forming polygons. The number, average size, perimeter and equivalent diameter of these polygons were quantified on replicas of 190 persons, 101 females and 89 males, from 6 months to 95 years of age. A good correlation was found between the age of the subjects and these four parameters. The evolution of these parameters was not linear but could be best described by a polynomial equation of fourth order for the number of polygons per field, and by an exponential equation for the three other parameters: average surface, perimeter and equivalent diameter of the polygons. A few details of the evolution with age of the skin surface patterns were different for males and females.

ISSN:0304-324X    

DOI:10.1159/000213212

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The influence of ageing on the ability of the brain cortex β-adrenoceptors to be regulated by very short stimulation with thyroid hormones has been investigated. Experiments were performed in 3-, 10-, 17- and 22-month-old mice using both thyroxine (T4) and triiodothyronine (T3) as stimulators and analyzing β-adrenergic receptor characteristics 15 and 60 min after hormone injection. Results showed that a statistically significant up-regulation is present in both young and old mice when treated with T3. On the contrary, after T4 injection only 3-month-old animals respond to such a short-term treatment, whereas older adult and old animals showed not statistically significant changes. Thus, the impairment in the T4-induced up-regulation starts already in adult mice and does not seem to further increase progressively with advancing age. From these findings it is suggested that the lack of responsiveness of β-adrenoceptors to T4 but not to T3 stimulation in adult and old mice may be due to relatively early impairment in the transformation of T4 into T3

ISSN:0304-324X    

DOI:10.1159/000213213

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

An aging antigen, senescent cell antigen, resides on the 911 amino acid membrane protein band 3. It marks cells for removal by initiating specific IgG binding. The active antigenic sites of the aging antigen have been localized to residues 538–554 and 778–827. Two peptides within these regions interact synergistically to generate a synthetic aging antigen that is an effective inhibitor of senescent cell IgG binding to old cells. We synthesized peptides corresponding to these residues (pep-ANION 1: SKLIKIFQDHPLQKTYN, and pep-COOH: LFKPPKYHPDVPYVKR). These are extracellular regions of band 3 containing lysines which are implicated in anion transport. The contribution of lysine to the antigenicity of the aging antigen and to anion transport was examined by chemically modifying the lysines on both synthetic peptides and whole cells, and by synthesizing peptides in which glycines or arginines were substituted for lysines. Anion transport sites were localized using 16- to 18-mer peptides followed by 6- to 8-mer peptides. Functional studies with the peptide pep-COOH indicate that it contains sulfate-binding sites and inhibits sulfate transport in addition to carrying aging antigenic determinants. Substitution of arginines or glycines for lysines in pep-COOH reduces the sulfate-binding properties of the peptide although significant inhibition still occurs. Residues 812–827 (pep-COOH) and 813–818 (N6, the six amino acids on the amino side of pep-COOH) and 822–839 are inhibitors of anion transport when used in equimolar amounts with sulfate suggesting that these regions may be transport regions in situ. Results of this study indicate that: (a) lysines are required for the integrity of the aging antigenic site; (b) pep-COOH (residues 812–827) is part of senescent cell antigen and an anion-binding site; (c) pep-ANION 1 (538–554), which has been reported to be a transport segment of band 3, does not bind sulfate; (d) residues 588–602 are part of an anion binding/transport segment; (e) band 3 residues 822–839 are part of an anion binding/transport site, and (f) lysines contribute to anion binding but are not the only amino acid(s) required for anion binding and, thus

ISSN:0304-324X    

DOI:10.1159/000213214

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Cu/Zn superoxide dismutase (Cu/Zn SOD), glutathione peroxidase (GPx) and catalase, which are the three main enzymes involved in cellular protection against damage due to oxygen-derived free radicals have been assayed in plasma and erythrocytes obtained from subjects with dementia of the Alzheimer type (DAT) and from controls. Blood samples were obtained from 25 patients with DAT and from age-matched subjects without diagnoses of neurological disease (non-DAT), as well as from younger individuals (reference group). Using appropriate statistical procedures, the three enzyme activities measured in blood of the elderly were decreased if compared to the younger reference group. Moreover, a significant increase in erythrocyte Cu/Zn SOD and catalase activities of DAT patients was observed compared to the non-DAT group. These results are discussed taking the free radical theory of aging into consideration.

ISSN:0304-324X    

DOI:10.1159/000213215

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

It is proposed that a centralized clock controlling ageing is located in the pineal gland with the calcification process occurring there providing a highly accurate bio-inorganic timing mechanism and the secreted melatonin carrying a signal to all cells in the organism. An explicit programme of data gathering and experiments suitable for the falsification of the proposal, which is consistent with presently known anatomical and physiological facts, is presented. The underlying motivation comes from evolutionary biology and the invariance, that is the allometry, of life expectancy curves.

ISSN:0304-324X    

DOI:10.1159/000213216

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Although it is usually assumed that Lamarckian inheritance does not and cannot occur, molecular mechanisms by which non-mutational changes acquired in one generation can be transmitted to the next are now known. These mechanisms involve changes in chromatin structure, rather than changes in DNA base sequence. It is argued that some parental-age effects and Lansing effects may be due to inherited changes in chromatin structure. Methods of testing this idea are suggested.

ISSN:0304-324X    

DOI:10.1159/000213217

出版商:S. Karger AG    

年代:1990

数据来源: Karger