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Z Srebro

Publications and source records attributed to Z Srebro.

At least 19 recordsLinked to original sources
PubMed1993

Communication of the intracranial space with sphenoid bone marrow in mice.

Tritiated thymidine and Ehrlich ascites tumour cells were injected intrathecally in adult Balb/c mice. Thymidine penetrated easily into the sphenoid bone marrow, where it labelled numerous leukocytes. The microvessel wall constituted a partly penetrable barrier against the infiltration of Ehrlich ascites tumour cells from arachnoid space into the bone marrow. A possible physiological role of the drainage of substances from the brain into the bone marrow is discussed.

Animals↗
PubMed1993

Genetic and epigenetic mechanisms for the limited lifespan and ageing of normal, diploid cells.

The genetic basis of the limited lifespan and apparently programmed number of divisions in normal, diploid cells is discussed. Two different mechanisms may underlie a programmed inhibition of cell divisions before they age and die: 1. A genetic mechanism involving the CpG sequence in promotor regions of genes. Inactive, but gradually activated basic function genes such as ribosomal and energy metabolism genes, when inactive have their CpG promotor sequences methylated. During each cell division a proportion of 5-methyl cytosines will be oxidatively deaminated leading to C to T transitions. After a certain number of divisions all methylated CpG islands will be mutated with consequent loss of viability and cell death. 2. An epigenetic mechanism involving the methylated promotor sequences of silent growth control genes. After a certain number of divisions with incomplete maintenance methylation, the growth control genes will be derepressed with consequent cessation of proliferation, decline of metabolic activity, ageing, and death.

Cell Physiological Phenomena↗
PubMed1991

Changes in RNA content of the hypothalamus of mice following insulin administration.

Cytoplasmic total RNA in neurons of the supraoptic nucleus, paraventricular nucleus, suprachiasmatic nucleus, and arcuate nucleus was determined cytophotometrically following a single intramuscular dose of 4 IU/kg insulin semilente. A significant decrease was observed after 3, 6, and 12 hours. A return towards normal values was evident after 24 hours and was full after 48 hours only in suprachiasmatic nucleus. Other hypothalamic nuclei did not reach the full normal value in the time interval examined, i.e. 48 hours post-injection.

Animals↗
PubMed1990

Short-term effect of kainic acid administration and its dependence on the circadian rhythm on cytoplasmic RNA content in neurons of the hypothalamus of mice.

Kainic acid in a dose of 12 micrograms/g given 1 hour before decapitation strongly modifies the content of cytoplasmic RNA, as determined cytophotometrically, in neurons of the supraoptic, paraventricular, and arcuate nuclei of the hypothalamus of adult mice. This stimulatory action of kainic acid was strongest during the night hours when the control animals exhibited the lowest amounts.

Animals↗
PubMed1989

The effect of kainic acid administration on the cytoplasmic RNA content of nucleus arcuatus neurons in mice.

A single intramuscular injection of kainic acid (12 micrograms/g body weight, dissolved in 0.1 ml of aqua pro injectione) was administered to adult, sexually mature, male mice. Control mice received equivalent amounts of aqua pro injectione only. Experimental animals were killed 24, 72, 120, and 192 h after the injection, and those of the control group simultaneously with the final experimental one. As determined cytophotometrically, in all the experimental groups a significant increase in the cytoplasmic RNA content of nucleus arcuatus neurons took place, this increase being highest 72 h after kainic acid treatment.

Animals↗
PubMed1989

Accumulation of lipofuscin in the brain of the frog, Rana temporaria, subjected to treatment with ultrasound.

Sexually mature male and female frogs, Rana temporaria L., taken from their natural habitat at the end of the hibernation period, were subjected to treatment with ultrasound of various duration. The ultrasound (frequency, 24 kHz, intensity 0.35 W/cm2) was applied over the whole body in a suitable water bath. Neurons of the nucleus infundibularis dorsalis, medulla oblongata, and the subfornical organ were studied. A considerable increase in the amount of autofluorescent lipofuscin pigment was observed in nerve cells of various regions of the brain of the treated animals. The largest amounts of the lipofuscin pigment were found in those treated for one hour and killed on the fourteenth day following sonication.

Animals↗
PubMed1989

The effect of bilateral adrenalectomy on the nucleus arcuatus-hypophysis and the circumventricular organs of Balb mice.

Three days following bilateral adrenalectomy the following findings were revealed in the hypothalamus-hypophysis and circum-ventricular organs of Balb mice: considerable enlargement of neuronal perikarya and nuclei in the nucleus arcuatus of the hypothalamus. Amitotic divisions were frequent in neurons and glial cells. Mitoses were also sporadically encountered. The pars distalis of the hypophysis showed typical post-adrenalectomy changes. In addition, enlargement of the so-called pars rostralis was observed. This part and the pars intermedia showed signs of enhanced secretion. The subfornical organ of the adrenalectomized animals was much smaller than in the controls. The subcommissural organ and pineal gland, on the contrary, were large and apparently actively secreting.

Adrenalectomy↗