Zeitschrift fur Gerontologie最新文献

In the literature on cognitive aging, differences between the cognitive abilities of young and older-adults have long been seen as supporting the view of an age-dependent cognitive deficit. However, findings are equivocal. In the context of more recent findings implying an age-dependent change in the efficiency of attentional and inhibition processes, the present study compares two groups of young and older adults concerning their ability to solve an everyday-like task. In order to effectively solve the task, subjects had to focus on goal-relevant information and, at the same time, inhibit irrelevant information. Subjects selected the relevant items from a shopping list and subsequently participated in a word detection experiment. The results demonstrate older adults taking more time overall to solve the task. However, they were differentiating and maintaining both relevant and irrelevant information in a way comparable to the younger adults. This finding indicates a deficit in older adults concerning the speed component of information processing. However, older adults do not seem to be impaired in their ability to focus on relevant information.

Transport of mRNA from nucleus to cytoplasm is an ATP-dependent process which occurs strictly vectorially. Because the mRNA is structurally bound during transport, mRNA transport is a "solid-state" process consisting of i) mRNA release from the nuclear matrix, ii) mRNA translocation through the nuclear pore, and iii) cytoskeletal binding. We identified and purified the following components involved in the translocation step: i) the nuclear envelope (NE) nucleoside triphosphatase (NTPase) which is stimulated by the 3'poly(A) tail of mRNA, ii) the poly(A)-recognizing mRNA carrier, iii) the NE protein kinase, and iv) the NE phosphatase. In addition, we found that an RNA helicase activity is present in NE, which also may be involved in RNA transport. Our results show that, besides poly(A), also double-stranded RNA structures may modulate RNA export. The amount of mRNA released from nuclei markedly decreases with age. Evidence is presented that this age-dependent change is caused by an impairment of polyadenylation of mRNA, hnRNA processing, release of mRNA from nuclear matrix, and translocations of mRNA from nuclear to cytoplasmic compartment (decrease in activities of NE NTPase, protein kinase, and phosphatase; decrease in poly(A)-binding affinity of mRNA carrier).

The nuclei binding of activated glucocorticoid receptor complexes (GRC) was significantly diminished in old, unstressed rats compared with young ones. In animals killed at different times after physiological stress there were no significant age-dependent differences in nuclei binding of GRC, which recurred in the cytoplasm after 60, 120 and 180 min, resp. Addition of Ca2+ and ATP, resp., to the incubation system increased the nuclei bound part of GRC, especially in young animals. ATP-stimulated translocation promoter (ASTP), isolated from rat liver cytosol, raised the nuclei binding of GRC in both age groups, whereby the increase was only significant in young animals. In cytosol of old rats ASTP were found in a lower concentration; moreover, the reaction between ASTP, GRC, and the template seems to be impaired.

In 12 of 32 elderly (> 65 years) hypertensives admitted with syncope, a diagnosis of orthostatic hypotension was made after a positive orthostatic tolerance test and extensive diagnostic evaluation with exclusion of other causes of syncope. Blood pressure of these 12 patients (pts.) after admission was 145 +/- 16/83 +/- 6 mmHg; at that time the pts. were treated with 2.6 +/- 1.6 different antihypertensive agents, and 67% of the pts. received a combination therapy. After reevaluation of treatment the pts. could be discharged with 1.3 +/- 0.7 different antihypertensive agents (significant difference, p < 0.02); in 25% of pts. (p < 0.05) combination therapy was still necessary. Before discharge casual blood pressure was 156 +/- 17/85 +/- mmHg (with the patient in the sitting position); average daytime ambulatory blood pressure was 145 +/- 18/80 +/- 5 mmHg. Three months after discharge 91% of pts. remained free of a new syncope. Orthostatic hypotension is a frequent cause of syncope in the hypertensive elderly; thus, their blood pressure should be checked more often in the sitting and standing position and by ambulatory monitoring.

From a mathematical model of aging are deduced three unit-free numbers. It is possible to calculate a critical value of the number beta t, where beta means the aging rate and t the chronological age of the organism. If beta t is greater than 1.84, then the theoretical life span is reached. Using an iteration method another unit-free number, namely, the quotient x of the growth rate and the aging rate beta is calculated to x = 4.5.

Aging rates of a sample which should represent the total population living in a district of Madrid were studied using the vectorial calculation as a mathematical model. The number of individuals who finally participated was 867, homogeneously distributed by sex and age decades in the age range of 20-100 years. A total of 15 variables was applied, but they were deduced from health-related data obtained from a special elaborated questionnaire. The resulting aging factor--a dimension to evaluate the aging acceleration--agrees with the corresponding results of biological aging studies previously published. Moreover, we contend that the obtained information from the simply sent questionnaire is accurate and of biological value, and would enable studies on the aging rates of populations.

A study of the antiviral 2',5'-oligoadenylate (2-5A) system in different tissues of rats of different age (newborn: 1-day old; young adult: 2-3 month old; middle-aged adult: 12-month old; and old: 32-33-month old) revealed that the activities of the 2-5A metabolic enzymes alter during aging and development. We demonstrate that soluble 2-5A synthase (2-5OAS) activity strongly increases after birth, reaching maximal levels in young adult and middle-aged adult animals, and then significantly decreases with age. In contrast, the activity of 2',3'-exoribonuclease which inactivates 2-5A increases by three-fold with age. The decrease in 2-5OAS activity and increase in 2-5A nuclease activity were found to result in a decrease in the cellular 2-5A content with age. The 2-5A-dependent ribonuclease (RNase L), which degrades viral RNA, also changes age-dependently. The amount and activity of this enzyme were determined in cross-linking experiments, in nitrocellulose binding assays; and in the ribosomal RNA cleavage assay. The livers of old rats display a 5-6-fold decrease in RNase L activity compared to the adult animal groups, while the amount of the enzyme does not change significantly during aging, with the exception of a drop by 30% in the nuclear matrix fraction. We conclude that the antiviral activity of the 2-5A system is impaired in old cells with the consequence that virus production cannot be efficiently suppressed.

The outflow of aqueous humor of the primate eye occurs across the filter system of the trabecular meshwork (TM) into Schlemm's canal. Cells of TM derived from a normal (TM-N-cells) and a glaucomatous human eye (TM-G-cells) were established in monolayer culture. The present comparative experiments were performed with cells kept in a defined serum-free medium (the aqueous humor is nearly protein-free!). Under these conditions the cells stay alive for several months in a non-proliferating state. TM-G-cells exhibited a lower synthesis rate of glycosaminoglycans-especially of hyaluronic acid (HA)--than TM-N-cells. Addition of 50-200 micrograms/ml ascorbic acid (the aqueous humor is characterized by a high ascorbic acid concentration of about 150 micrograms/ml) to the culture medium resulted in a significant dose-dependent stimulation of HA-synthesis and secretion, which was relatively stronger in case of TM-G-cells than with TM-N-cells. Thus, the results suggest a role of ascorbic acid in the probably membrane-localized HA-synthesis. Functions of ascorbic acid and HA for the morphological and functional integrity of the TM-cells in vitro and the outflow apparatus in vivo were discussed.

We have considered the question of the quantification of differentiation processes. We investigated articular cartilage of the Caput femoris in 22 cases aged from 0 to 77 years. We measured cell size and volume density. During aging a shifting of the layer with the maximum cell size in relation to the joint surface as well as the formation of two layers with different volume densities take place. We believe that the changes in nutritional and load conditions during life play a role in these processes. We describe these with the term "diversification", characterizing the process of the changing of the degree of structural order.