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Biomedical subjects

M Karasek

Publications and source records attributed to M Karasek.

At least 145 records · Page 8Linked to original sources
PubMed1965

Chromosome studies of normal and psoriatic skin fibroblasts.

A method for obtaining large numbers of fibroblasts from punch biopsies of skin tissue and a procedure for the visualization of chromosomes from these cells are presented in detail. The chromosomes are well separated, and fine details of their structure are seen. A study was made of 275 cells from apparently normal and from involved areas of skin from patients with psoriasis. No changes either in the number or in the fine structure of the chromosomes were observed.

Adult↗
PubMedDate not supplied

Melatonin, human aging, and age-related diseases.

The worldwide prolongation of the mean life expectancy has resulted in a rapid increase of the size of the elderly population (over the age of 60), both in numbers and as a proportion of the whole. As a consequence, increasing the number of potential beneficiaries of health and pension funds, mainly those aged 65 and over raises many social and economic problems since they are supported by a relatively smaller number of potential contributors, i.e. those in the economically active ages between 18 and 64. Therefore, there is a search for any therapeutic agent improving quality of life in the elderly. A role for melatonin as such a compound was recently suggested. In this survey, data on the possible role of melatonin in human aging and age-related diseases are briefly presented. Undoubtedly the aging process is multi-factorial, and no single factor has been identified which satisfactorily explains the phenomenon. Although many theories relating the pineal gland and its secretory product melatonin to aging have been proposed, the role of this agent in the aging process is still unclear. However, for several reasons it seems reasonable to postulate a role for melatonin in this process. Melatonin levels decline gradually over the life-span and may be related to lowered sleep efficacy, very often associated with advancing age, as well as to deterioration of many circadian rhythms. Melatonin exhibits immunomodulatory properties, and a remodeling of immune system function is an integral part of aging. Finally, because melatonin is a potent free radical scavenger, its deficiency may result in reduced antioxidant protection in the elderly which may have significance not only for aging per se but also may contribute to the incidence or severity of some age-related diseases. Presently available data do not allow us to conclude that melatonin may have a role in extending normal longevity. However, although melatonin cannot be recognized as 'rejuvenating' agent, some of its actions may be beneficial for the aging process. Administration of melatonin may improve temporal organization in advanced age. Moreover, it has beneficial effects on sleep as well as age-related diseases. Although recommendations of melatonin supplementation in elderly should be considered, there is a need for extensive studies on the use of melatonin in order to improve the quality of life in advanced age.

Aged↗
PubMedDate not supplied

Antiproliferative effects of melatonin and CGP 52608.

The antiproliferative effects of melatonin and CGP 52608, an exogenous ligand for RZR/ROR receptors, are compared in the present paper. Both compounds exerted similar inhibitory effects on the proliferation of neoplastic cells in mouse colonic adenocarcinoma, DU 145 human prostate cancer, MCF-7 human breast carcinoma, and rat diethylstilbestrol-induced prolactinoma. Although it has been suggested that melatonin may influence the proliferation of tumor cells via RZR/ROR receptors, it cannot be excluded that the antiproliferative effects of melatonin and CGP 52608 are unrelated and mediated by different intracellular mechanisms.

Animals↗
PubMedDate not supplied

Serial transplants of 7,12-dimethylbenz[a]anthracene-induced mammary tumors in Fischer rats as model system for human breast cancer. 3. Quantitative ultrastructural studies of the pinealocytes and plasma melatonin concentrations in rats bearing an advanced passage of the tumor.

The aim of the present study was to investigate the ultrastructure of pinealocytes and plasma melatonin concentrations in Fischer rats bearing an advanced (14th) passage 7,12-dimethylbenz[a]anthracene-induced mammary tumor. Quantitative ultrastructural analysis of the cell size and relative volumes of various cell organelles as well as the number of dense-core vesicles was performed in pinealocytes of the animals killed either during the daytime (15.00 h) or at night (3.00 h) 1 month after tumor transplantation. No significant differences between control and tumor-bearing animals were observed either during the daytime or at night. However, plasma melatonin concentrations in tumor-bearing rats killed at 3.00 h were suppressed by 35% (p < 0.025) when compared to the control animals killed at the same time.

9,10-Dimethyl-1,2-benzanthracene↗