Biomedical subjects

D Gershon

Publications and source records attributed to D Gershon.

At least 181 records · Page 10Linked to original sources

PubMed1986

Computer assisted scanning laser monitor of optical quality of the excised crystalline lens.

We describe a technique, involving the projection of low power laser beams through excised lenses in solution, that makes it possible to measure photographically lens optical aberrations. Preliminary work indicates that the laser method can be used in combination with lens culture experiments as a means of monitoring changes in studies of lens biology. The goal of this research is the development of an effective in vitro optical monitor of ocular lenses in order to assist the study of the biochemistry of lens aging and cataractogenesis and be used as a sensitive toxicity measuring device.

Aging↗

PubMed1985

Evidence of Schwann cell degeneration in the aging mouse motor end-plate region.

An ultrastructural evaluation was made of the changes encountered in the motor endplates of the gastrocnemius muscle of old mice in comparison with young-adult mice. In old, 27-month-old mice, a great variety of changes were recorded. The main abnormalities occurred in the axon terminals, the myoneural junctional folds, and the endomysial space. Loss of synaptic vesicles and mitochondria and vacuolization of axon terminals were common. Shrinkage and degenerative changes of axon terminals were noticed. The end-plate abnormalities were closely associated with an increased amount of collagen tissue, degenerated Schwann cells, and cell debris. Degenerated Schwann cells were not encountered in young-adult mice. In the old group, endplates of normal appearance occurred in the proportion of 40%. The young group had normally structured end-plates in the proportion of 85%. The lesions described are not specific for the aging process.

Aging↗

PubMed1985

Identification of intracellular degradation intermediates of aldolase B by antiserum to the denatured enzyme.

A method has been developed that enables us to identify intracellular degradation intermediates of fructose-bisphosphate aldolase B (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13). This method is based on the use of antibody against thoroughly denatured purified aldolase. This antibody has been shown to recognize only denatured molecules, and it did not interact with "native" enzyme. supernatants (24,000 X g for 30 min) of liver and kidney homogenates were incubated with antiserum to denatured enzyme. The antigen-antibody precipitates thus formed were subjected to NaDodSO4/PAGE, followed by electrotransfer to nitrocellulose paper and immunodecoration with antiserum to denatured enzyme and 125I-labeled protein A. Seven peptides with molecular weights ranging from 38,000 (that of the intact subunit) to 18,000, which cross-reacted antigenically with denatured fructose-bisphosphate aldolase, could be identified in liver. The longest three peptides were also present in kidney. The possibility that these peptides were artifacts of homogenization was ruled out as follows: 125I-labeled tagged purified native aldolase was added to the buffer prior to liver homogenization. The homogenates were than subjected to NaDodSO4/PAGE followed by autoradiography, and the labeled enzyme was shown to remain intact. This method is suggested for general use in the search for degradation products of other cellular proteins.

Animals↗

PubMed1985

Some characteristics of the human erythrocyte as a function of donor and cell age.

Erythrocytes from healthy human donors of various ages (18-93 years) were separated on Percoll into four density fractions. Increased cell density has been reported to correlate with the age of the erythrocyte. Aged individuals, while having normal hematocrits, show an increased percentage of low-density young erythrocytes and almost twice as many reticulocytes in their circulation as do young adults. This evidence for increased, well-compensated, red cell turnover in elderly humans is supported by the finding in older individuals of increased levels of erythrocytes bearing autologous IgG on their membranes. Using fluorescent anti-IgG, erythrocytes with bound autologous IgG could be found in all density fractions from donors of all age groups. The old donors had an increased number of fluorescent cells that appeared in all density fractions albeit with a definite skewing toward the more dense cell fractions. Erythrocytes from young donors had higher levels of intact hemoglobin per cell than those from old donors. The relevance of these results to the aging process and the ability of senescing individuals to withstand hematologic stress are discussed.

Adult↗

PubMed1984

Decreased enzymic protection and increased sensitivity to oxidative damage in erythrocytes as a function of cell and donor aging.

Erythrocytes from young and old rats were separated into four age fractions by density-gradient centrifugation. The specific activities per cell were determined for glucose-6-phosphate dehydrogenase (EC 1.1.1.49), glutathione peroxidase (EC 1.11.1.9), glutathione reductase (EC 1.6.4.2) and catalase (EC 1.11.1.6). Decreased specific activities were observed with increasing cell age for all four enzymes in both young and old animals. In addition, significant differences in the activities of these enzymes were observed between cells of the same age fraction from young and old donors. Susceptibility of fractionated erythrocytes to oxidative attack in vitro generated by incubation with xanthine/xanthine oxidase increased with both cell and animal age. The amount of membrane-lipid peroxidation also increased with cell and animal aging, as measured by both thiobarbituric acid and fluorescent chromolipid assays. Increases of 2-3-fold in the contents of lipid peroxides were observed between the youngest and oldest age fractions of young rats. Lipid peroxide contents in young cells of old animals were equal to those in old erythrocytes from young rats and increased by 30% with cell aging in the old donors. These results suggest that the extent of enzymic protection against oxidative and peroxidative damage decreases with erythrocyte aging. More importantly, enzymic protection in cells of old rats is considerably decreased already in the early stages of their lifespan.

Age Factors↗

PubMed1984

Glyceraldehyde 3-phosphate dehydrogenase activity in rat and human lenses and the fate of enzyme molecules in the aging lens.

The specific activity of the enzyme glyceraldehyde 3-phosphate dehydrogenase declines as a function of age. Immunotitration with monospecific antibodies demonstrated that with age there is an increase of catalytically defective, but antigenically reactive enzyme molecules in the lens. Antiserum, produced against denatured enzyme, removed the inactive molecules from lens homogenates, without effects on the levels of enzyme activity. These studies suggest that inactive enzyme molecules in aging lenses are totally devoid of catalytic activity, and are at least partially denatured.

Adult↗

PubMed1983

The presence of NADPH-glyceraldehyde 3-phosphate oxidoreductase in macrophages.

The existence of an NADPH-oxidoreductase which utilizes D-glyceraldehyde 3-phosphate as substrate has been demonstrated in mouse peritoneal macrophages. D-Glyceraldehyde could also serve as substrate, albeit with a 10-fold lower efficiency. No NADH oxidation could be demonstrated with either substrate. Addition of D-glyceraldehyde to cultured macrophages increased the rate of activity of the hexose monophosphate shunt to about 65% of the level observed in zymosan A-stimulated macrophages. The possible involvement of the oxidoreductase in this phenomenon and in the inhibitory effect of D-glyceraldehyde on the production of oxygen free radicals by zymosan-stimulated cells is discussed.

Animals↗

PubMed1983

Studies on the fate of aldolase molecules in the aging rat lens.

It was found that aldolase activity declined considerably in the lens of adult animals with increasing age. Immunoassay showed that defective aldolase C molecules were accumulated. In addition, antibody prepared against denatured enzyme preferentially removes inactive molecules from lens homogenates without affecting active molecules. It is concluded that defective aldolase molecules encountered in aging lenses are at least partially denatured and are inactive.

Aging↗

PubMed1983

Morphometric analysis of aging skeletal muscle following endurance training.

Aging of skeletal muscle in the hindleg of the mouse is accompanied by a progressive increase in the amount of the interstitial tissue and especially that of lipid cells and fibroblasts. Quantitative analysis indicates that there was a nonsignificant increase in the total number of muscle fibers per unit area, perhaps due to a splitting process. The proportion of high oxidative fibers was decreased to a nonsignificant degree, and the remaining high oxidative fibers underwent a significant compensatory hypertrophy. Concomitantly, the number of low oxidative fibers increased significantly. This study revealed that endurance training in young animals induced morphometric changes very similar to those noticed in intact aging animals (i.e., splitting phenomenon, hypertrophy of high oxidative fibers, and an increased proportion of low oxidative fibers). It also became apparent that the skeletal muscle of old animals lacks the capacity to respond to enforced training, except for a further increase in the proportion of low oxidative fibers. It appears that aging muscle is unable to adapt to changing environmental circumstances.

Aging↗

PubMed1983

The effects of enforced running on the gastrocnemius muscle in aging mice: an ultrastructural study.

C57BL/6J mice (6, 19 and 27 months old) were trained in an electrically driven treadmill for a total period of 10 weeks. The training program started with 5 min. run per day and reached a maximum of 30 min. per day. Light and electron microscopy examinations of the gastrocnemius muscle showed that in young animals endurance training did not evoke any appreciable changes. In contrast, both test animals and their controls in the old group revealed clear signs of muscle cell atrophy which for the most part was accompanied by focal loss of myofilaments, mitochondrial changes and an increase in the amount of endomyseal collagen fibrils. In the old-trained group, the most obvious abnormality comprised of multiplication of both the T-tubules and of the tubules of the sarcoplasmic reticulum. Consequently, most of these animals showed the formation of tubular aggregates in their gastrocnemius muscle. Hence, it appears that endurance training in old animals tends to enhance the regressive changes that accompany the aging process of mammalian skeletal muscle.

Aging↗

PubMed1983

The effect of donor and cell age on several characteristics of rat erythrocytes.

Erythrocytes from young and old WF rats were separated by discontinuous density gradient centrifugation. The density and mean life span of the erythrocytes were correlated with cell age by 59Fe pulse labeling. A mean half-life of 40 and 25 days was measured for erythrocytes in young and old animals, respectively, with a corresponding 4-fold increase of young cells and a 2.3-fold increase in circulating reticulocytes in old animals. Thus, the old rat has a chronologically younger population of circulating erythrocytes than the young animal. The mean hemoglobin concentration of red cells from old, but not young animals, was found to decrease from 18.5 +/- 2.1 pg to 11.8 +/- 1.8 pg per cell with increasing cell age. Premature exposure of a surface antigen, which is recognized by antibodies present in the serum, was observed in cells of old animals. This antigen-antibody complex is presumed to trigger sequestration by phagocytosis of senescent erythrocytes. The contribution of the observed age-related changes to early erythrocyte sequestration in old animals is discussed.

Aging↗

PubMed1982

Decreased protein and puromycinyl-peptide degradation in livers of senescent mice.

Liver protein-degradation rates were determined in young and old C57B1 mice by the method of Swick & Ip [(1974) J. Biol. Chem. 249, 6836-6841]. The results indicated a marked age-related increase in the half-lives of short-lived proteins in the nuclear, mitochondrial, lysosomal and 100000 g-supernatant cellular fractions and in total trichloroacetic acid-precipitable proteins. The efficiency of the degradation system in removing aberrant proteins from livers of young and old mice was tested. The time required for 50% disappearance of puromycinyl-peptides changed from about 20 min in 6-month-old mice to approx. 150 min in 24-month-old animals. These findings suggest that in old animals the proteolytic activity involved in degradation of aberrant proteins, and presumably of "native proteins, is markedly defective.

Aging↗

PubMed1982