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V Zs-Nagy

Publications and source records attributed to V Zs-Nagy.

10 recordsLinked to original sources
PubMed1989

The lack of age-pigments and the alterations in intracellular monovalent electrolytes in spontaneously hypertensive, stroke-prone (SHRsp) rats as revealed by electron microscopy and X-ray microanalysis.

Male, spontaneously hypertensive, stroke-prone (SHRsp) rats established by Okamoto et al. (1974) were studied. About 80% of the males of this strain have a particularly short life span (33-41 weeks); they display a considerable hypertension (above 220 mmHg) and a tendency for plurifocal brain strokes. Hypertension and strokes can be provoked in an accelerated and synchronized fashion by supplementing 1% NaCl into their drinking water. Symptoms of the appearance of brain strokes can be judged from characteristic signs of motor disorders, and can be established also by pathohistology. Since hypertension and arteriosclerosis are frequently involved in aging, the question we intended to answer was whether these animals may represent a model of the normal aging process or not. Two approaches are described: (1) Accumulation of lipofuscin granules in their brain, liver and myocardium was followed by transmission electron microscopy before and after the appearance of strokes. It has been established that these tissues do not show any typical accumulation of lipofuscin granules, although submicroscopic signs of an enhanced damage of cell organelles (especially of mitochondria in liver and brain cells, but not in myocardium) were encountered. (2) The intracellular monovalent composition in the brain and liver was measured by using bulk-specimen X-ray microanalysis. The intracellular Na-content (mEq/kg water) was significantly higher (170-200%) in both the brain and liver cells, whereas the K-content increased only moderately (118-130%). The results suggest that although the SHRsp rats do not represent a direct model for the normal aging process from the point of view of lipofuscin accumulation, the shifts of the monovalent electrolyte contents in the brain and liver cells observed already in the youngest ages, are similar to those observed in aged normal rats. The theoretical consequences of such a conclusion are discussed.

Aging↗
PubMed1988

Possibilities and limitations of the smearing technique for cellular studies in compact tissues: a transmission electron microscopic analysis of liver smears.

During the last decade a sophisticated biophysical technique called fluorescence recovery after photobleaching (FRAP) has become available for the measurement of lateral diffusion constants of lipids and proteins in the cell membrane. The information obtainable by this method is of great importance; however, the applicability of this method is seriously hindered by the fact that it has been elaborated mostly for isolated, individual cells. On the other hand, the use of freshly prepared cells from compact tissues for such studies is highly desirable. Therefore, a special smearing method was devised (using liver cells) for this purpose. The present paper describes (i) the method of standardization of the smearing technique, (ii) the ultrastructural features of the liver cells when studying the liver smears by means of transmission electron microscopy. The possibilities and limitations of this method are discussed. According to the observations, under well-defined conditions the structural integrity of hepatocytes is maintained in the liver smears to such an extent that they are suitable for FRAP experiments.

Animals↗
PubMed1986

Age-dependent decrease of the lateral diffusion constant of proteins in the plasma membrane of hepatocytes as revealed by fluorescence recovery after photobleaching in tissue smears.

When fresh liver is smeared on slides and incubated in Krebs-Henseleit Ringer solution containing 1 mM H2O2 at 37 degrees C, a yellowish-green autofluorescence develops in the hepatocyte plasma membrane. Indirect evidence shows that this peroxide-induced autofluorescence (PIAF) is due most probably to chemical reactions between proteins and the malondialdehyde produced by the membrane lipid peroxidation. Although the chemical nature of the PIAF has not been clarified yet, it is suitable under certain conditions for the measurement of the average lateral diffusion constant of the membrane proteins by means of the fluorescence recovery after photobleaching (FRAP) technique without the addition of any external fluorescent label. Analysis of four age groups for both sexes of Fischer 344 rats (3-5 rats per group, total 32) from 2 to 31 months of age revealed a significant negative linear correlation of the lateral diffusion constant of proteins with age in both sexes, with the slope of the females being somewhat smaller. Young males showed a diffusion constant about 2.8 X 10(-10) decreasing to 1.7 X 10(-10) cm2 X s-1 by 31 months of age at 37 degrees C, whereas the respective values in females were 2.7 X 10(-10) and 1.9 X 10(-10). The results are consistent with the predictions of the membrane hypothesis of aging, according to which an age-dependent loss of the passive permeability of the cell membrane for potassium (and probably for water) is the crucial point of the cellular aging.

Aging↗
PubMed1986

Age-estimations of rats based on the average lateral diffusion constant of hepatocyte membrane proteins as revealed by fluorescence recovery after photobleaching.

A method has been developed recently for measuring the average lateral diffusion constant of the proteins (D) in the cell membrane of hepatocytes in liver smears by fluorescence recovery after photobleaching (FRAP). A peroxide-induced autofluorescence (PIAF) of the membrane proteins was used as a fluorescent label. It has been established that D displays a significant negative linear correlation with age. The present paper describes age-estimations carried out on 12 male Fischer 344 rats (7-29 months of age) in so-called "blind experiments": the operator knew only the sex of the rat, determined D from a small piece of the freshly removed liver, and estimated the age of the rat from the age-dependent regression line for D established previously on 16 other Fischer 344 male rats of various ages. There was a strong correlation of the estimated age with the actual one (r = 0.92), the slope of the regression line was 0.98 and its intercept differed from 0 by only 0.5 months. These results indicate that D may play a decisive role in the determination of membrane functions as predicted by the membrane hypothesis of aging.

Aging↗
PubMed1978

In vivo stimulation of nerve cells by phytohemagglutinin. I. Alterations of some cytological aging parameters in rat brain cells.

Phytohemagglutinin P (PHA-P) was administered in form of intralumbar injection to old (24-27 months) female Wistar rats. PHA-P has an inductive effect also on the nerve cells. The thermal denaturation characteristics of the DNA in situ as well as the numerical density of perichromatin granules being connected to the extranucleolar RNA synthesis returned practically to the young levels in the large brain cortical cells and in the cerebellar granular cells 20 h after the injection. The reversal of these aging phenomena was accompanied by a significant decrease of intranuclear and intracytoplasmic K+ content measured by X-ray microanalysis in the dry mass, whereas Na+ and Cl- remained unchanged. If PHA-P causes also some (1-2%) rehydration of the old neurons, the total ionic strength in the cell due to the monovalents may even reach the young level. The possible regulatory role of the ionic strength and the Na+/K+ ratio in the chromatin function is discussed on the basis of experimental data. It is the first time that the reversibility of some cytological aging parameters has been demonstrated in vivo.

Animals↗
PubMed1977

Alterations in the numerical density of perichromatin granules in different tissues during ageing and cell differentiation.

Perichromatin granules (PG) were counted on electron micrographs of different tissues taken from young and old female Wistar rats as well as in the basal and spinous layers of adult human epidermis. A significant age-dependent decrease was observed in the following cell types: large brain cortical cells, cerebellar granular cells, hepatocytes, parotid gland cells. No significant decrease was found in the heart muscle nuclei and in the erythroblasts of identical maturation level. The number of PG decreased during the erythroblast maturation almost to zero, and increased in the cells of spinous layer of human epidermis as compared to the basal cells. There is a very wide variation in the number of PG per nucleus between the different tissues. The correlation between the transcriptional activity, the protein synthesis, ageing and cell differentiation is discussed.

Adult↗
PubMed1977

Age-dependent increase of intranuclear monovalent electrolytes as revealed by quantitative energy dispersive x-ray microanalysis.

The concentration of univalent electrolytes in the cell nucleus and cytoplasm of the big neurons of the brain and in hepatocytes was established in young, mature and old rats by means of microanalysis with X-rays. It was demonstrated that the Na+ and Cl-- content increases with aging in both tissues, while K+ increases in the neurons but not in the nuclei of the hepatocytes, At the same time some ions in the cytoplasm increase, while others decrease or remain stable. If a possible loss of water during aging is taken into consideration the result is a considerable increase in ion concentration in the nucleus. This may be regarded as one of the principal reasons for the increased density which accompanies aging and possibly as one of the cause of the aging process.

Aging↗
PubMed1977

On the reversibility of some cytological ageing parameters of rat brain cells by phytohemagglutinin.

It has been shown that the thermal stability of DNA in the brain cortical cells increases with the age. At the same time, the number of perichromatin granules being connected in some way to the messenger RNA synthesis and transport of the interphase nuclei, decreases in the same cells. In vivo treatment of the old animals by mitogens like phytohemagglutinin induced a reversal of both ageing phenomena: the thermal stability of DNA returned almost completely to that of the young animals, whereas the number of perichromatin granules rised again to the young level.

Aging↗