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Biomedical subjects

V Mares

Publications and source records attributed to V Mares.

At least 73 records · Page 4Linked to original sources
PubMed1987

Purkinje cell maturation in the light of RNA synthesis.

Wistar rats 1- to 90-day-old received an injection of 3H-uridine and were killed 20 min to 44 h later. Autoradiographic examination revealed the highest grain count densities in Purkinje cell nuclei around postnatal day (PD) 6 while the incidence of labelled nuclei stayed at the peak values till PD 15. Silver staining of Purkinje cell nuclei showed that the expression of nucleolar r-RNA coding genes is maximal at PD 15; in some cells it even slightly exceeds adult values. After PD 15, the percentage of labelled Purkinje cell nuclei declined; this was more pronounced in the nucleolar region than outside the nucleolus. The percentage of cells with cytoplasmic labelling culminated on PD 15. The highest grain counts were found in Purkinje cell cytoplasm on PD 6 at 44 h p.i. interval. Reversal in nuclear grain counts at 2 and 6 h p.i. intervals observed between PD 15 and PD 25 suggests faster degradation, or processing and export, of a newly synthesized nuclear RNA in these age groups. Frequency distribution analysis of grain count densities revealed a small group of Purkinje cells with higher incorporation of 3H-uridine both in the nucleolar region and the whole nucleus at PD 15. In situ hybridization of 3H-r-RNA revealed a slight binding excess to DNA of some Purkinje cell nuclei but not in granule cells of 1-month-old rats. These data, together with those published recently by Brodsky et al. (1985), indicate an uneven structural organization and partial overexpression of the genom coding r-RNA synthesis in the population of Purkinje cells.

Aging↗
PubMed1987

Cyclic AMP levels of C6 glioma cells treated with cis-dichlorodiammine platinum (cis-DDP).

Rat C6 glioma cells were cultured for 3-4 days in MEM supplemented with bovine serum. After 10 min incubation of cells with 0.075, 1.0 or 7.5 micrograms ml-1 cis-DDP the basal cAMP levels (7.87 +/- 0.4 pmoles mg-1 protein) were not affected. In the presence of a phosphodiesterase inhibitor, IBMX, an increase of cAMP occurred; the later was more pronounced in cis-DDP treated cells than in the controls. This suggests that both adenylate cyclase and cAMP-phosphodiesterase were proportionally influenced at this period and that the stimulatory effect of cis-DDP on AC could be demonstrated only when increased activity of PDE had been blocked by IBMX. At later time intervals (10 h-40 h), a 5- to 17-fold elevation of cAMP levels was observed even in the absence of IBMX. Pretreatment of the cells with cis-DDP significantly potentiated cAMP accumulation in response to NE alone and to cis-DDP plus NE could be prevented to a large extent by propranolol; in cis-DDP treated cells the propranolol protection was more effective, both in the absence and the presence of IBMX. The pretreatment of cells with an alpha-blocker, Regitin, did not significantly influence cAMP accumulation. The results indicate that the cis-DDP stimulated cAMP response to NE is mediated via an interaction with beta-adrenergic receptors. The late increase in cAMP content may be a mediator of the morphological changes in these cells following exposure to cis-DDP.

Animals↗
PubMed1986

Influence of cis-dichlorodiammineplatinum on the structure of the immature rat cerebellum.

Groups of 6- to 7-day-old and 10- to 11-day-old rats received cis-dichlorodiammineplatinum (cis-DDP) or inactive trans-DDP subcutaneously and were killed after 1, 6, 10, 15, or 21 days. In both age groups the acute effect (postinjection day 1) was most obvious in the germinal external granular layer (EGL), where many cells underwent shrinkage necrosis (pyknosis, apoptosis); the latter were more frequent within the fissures than on the surface of the cerebellar folia. Cell debris were often seen to be engulfed by macrophages, Bergmann cell fibers, and meningocytes. Bergmann cell bodies were swollen and the nuclei of Purkinje cells as well as of surviving cells of the EGL were enlarged. No comparable effects were observed in animals that had received an injection of trans-DDP in the same dose. Toward postinjection (p.i.) day 6, pyknotic cells disappeared from the EGL or, after the larger doses of cis-DDP, substantially decreased in number. Small nests of pyknotic cells appeared, however, at some places of the internal granular layer (IGL). The EGL was discontinuous or thinner in both age groups. In the IGL and molecular layer (ML) multiple focal fresh hemorrhages appeared together with some macrophages. The packing cell density in the IGL was less than in the controls, especially at the top of the cerebellar folia, i.e., contrary to the distribution of the primary damage in the EGL. Later, at p.i. day 10, ectopic nests of the IGL occurred occasionally in animals injected when 10 to 11 days old and severe atrophy of the ML and Purkinje cell population was observed at some places. At p.i. days 15 to 21, invasion of microglia-like cells appeared in the IGL and in some regions of the ML. Occasionally, subpial hemorrhages occurred at this interval. The acute damage caused by cis-DDP is thus similar to the effect of X rays or some, but not all, drugs with a cytostatic action. In addition, a more profound influence on dividing cells of the EGL within the fissures and distinct capillary lesions, indicated by hemorrhages, were found after cis-DDP. As in other experimental models, the acute cis-DDP damage of the immature cerebellum was partly repaired within a few p.i. days. Spatial difference of the repair process was inferred from the packing cell density in the IGL measured at the top and bottom of the cerebellar folia.

Animals↗
PubMed1985

DNA content in nerve-cell nucleus. A biochemical and cytophotometric study of the rat cerebrum.

The cerebral nuclei of 30-day-old rats were separated by a two-step gradient centrifugation into the fractions of large and small nuclei. The DNA content per nucleus was determined biochemically and cytophotometrically in these fractions as well as in the non-separated cerebellar and liver-cell nuclei used as reference cells. The DNA content of large and/or mainly neuronal, and the small and/or glial cell-enriched nuclei were 6.74 +/- 0.51 and 6.21 +/- 0.30 pg, respectively, and in the cerebellum 6.10 +/- 0.28 pg per nucleus. The DNA-content values determined cytophotometrically in Feulgen-stained samples of large and small bulk isolated cortical nuclei ranged within the diploid limits, indicated by a part of a liver-cell population measured in parallel. No evidence for the large scale existence of an "extra-DNA" reported earlier [Bregnard, Knuesel and Kuenzle (1975) Histochemie 43, 59-61; Bregnard, Kuenzle and Ruch (1977) Expl Cell Res. 107, 151-157; Kuenzle, Bregnard, Hübschner and Ruch (1978) Expl Cell Res. 113, 151-160] in cortical neurons has thus been obtained.

Animals↗
PubMed1985

Regional and cellular differences in fucosylation of glycomacromolecules in the mouse brain. A biochemical and autoradiographic study of early postnatal and adolescent animals.

Mice of CBA strain of both sex were injected with [3H]fucose at age 2, 6, 12 or 30 days and the incorporation was determined biochemically 45, 90 and 180 min later. Biochemical measurements of the whole brain (at 90 min postinjection interval) revealed a stepwise age decrease in the amount of incorporated isotope (per mg protein). The amount of [3H]fucose available in the brain has however been found to decrease with age while the degree of its utilization increases. Thus, after correction of the data on [3H]fucose incorporation for the pool of the free isotope, a transient increase in fucosylation rate appeared at postnatal day 12 while the differences among 2-, 6- and 30-day-old animals became negligible. Further, the synthesis of fucosylated soluble glycomacromolecules appeared relatively higher at postnatal day 2 than in older age groups. Examination of different brain regions revealed that the rate of fucosylation is relatively highest in the olfactory bulbs; this prevalence starts appearing with age and becomes most evident in 30-day-old mice. Autoradiography carried out with 6- and 12-day-old animals revealed that the incorporation of [3H]fucose into meningovascular apparatus and the choroid plexus is a few times higher than into brain parenchyma. The regional differences appeared to be similar to those indicated by the biochemical data. Cellular analysis has shown that the incorporation is relatively higher in the cytoplasm of large projecting neurons of the cerebellum, hippocampus and the olfactory bulbs; in the latter region high amounts of macromolecule-bound [3H]fucose also appeared in the synaptic glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Growth and polyploidization of the liver of early postnatal rats treated with bleomycin.

Bleomycin was administered to 6- and 10-day-old rats and its effects were examined after a two-week survival period. Decreases in body weight and some phenotype abnormalities occurred in both age groups. Decreased relative liver weight (g/g b.w.) was observed only in animals injected on PD 10. DNA microdensitometry and microfluorometry (Feulgen reaction and Hoechst 33342 staining) revealed an increase in the frequency of intermediate DNA values in animals injected on PD6 and killed on PD20. In older animals, i.e. in rats injected on PD10 and killed on PD25, increases in 4c mononucleate and 8c binucleate cells and also a reduction of the relative number of binucleate cells appeared, as compared with age-matched controls. In both age groups, karyological abnormalities, including micronucleate cells and imbalanced DNA content in binucleate cells, were observed.

Aging↗
PubMed1985

An attempt to influence DNA content in postmitotic Purkinje cells of the cerebellum.

Feulgen-DNA content has been measured cytophotometrically in granule and Purkinje cells of the rat and mouse cerebellum. The study has confirmed that under normal conditions a very small part of the P. cell population in rats (less than 3%) possesses a Feulgen-DNA surplus ranging from 2C to 4C. In mice, the hyperdiploid (H2C) P. cells are even more rare. The occurrence of H2C-P. cells in rats and probably also in mice has not been substantially changed in animals exposed to factors interfering with chromatin structure and/or its template activity; the H2C-P. cells seem to be slightly more frequent after injecting mice with corticoids (Urbason) or in animals suffering from ectromelia or hereditary Purkinje cell degeneration. The incidence of H2C-P. cells has neither been substantially affected by experimental conditions which are known to lead to functional and/or metabolic stimulation of the cerebellum. Functional changes in the number of H2C-P. cell nuclei may, however, be short-term or transient in character and therefore might have excaped detection in our models. The findings rule out an impact of some reasons suspected for the artefactual origin of Feulgen H2C DNA values as e.g. compactness of the chromatin.

Acoustic Stimulation↗
PubMed1985

Alpha-fetoprotein in the brain of embryonic pigs.

Alpha-fetoprotein (AFP) has been screened in the brain of pig embryos by immunocytofluorescence, crossed immunoelectrophoresis and the immunoblotting technique. Immunocytochemistry showed that the cell and tissue localization of AFP changes with age of the embryos, and/or maturation of the brain. At the earliest stages studied (embryonic days (ED) 26 to 28), the AFP in the brain prevails near the cerebral ventricles, while later (ED 35-46) AFP also appears in higher concentrations in the differentiating parenchyma of some regions of the brain (especially in deep layers of the cortical plate or the region of the differentiating hippocampus) and spinal cord. Its intracellular presence was well evident in the large neuroblasts of these regions. During the 3rd month of embryonic life AFP starts to disappear from the brain parenchyma. At all ages studied, bright fluorescence in the choroid plexus and the meningovascular apparatus is evident. In the choroid plexus as well as ependymal cells a mosaic-like pattern of fluorescence appeared, especially near its invagination into the lateral ventricles; the latter suggests transependymal transport of AFP by some cells. Single and crossed immunoelectrophoresis revealed one reacting band in the water extract of homogenate of the brain of 35-day-old pig embryos. Similarly, only one band has been stained in SDS electrophoretograms prepared from such extracts and stained by the immunoblotting technique; its molecular weight corresponded to the pig AFP. In contrast to the brain the AFP band in the liver was also found in the membrane fraction. It is concluded that maximal tissue concentrations of AFP in the pig brain are attained during the second embryonic month and that, in addition to extracellular fluids, it is also transitionally present in the cytoplasmic compartment of brain cells, especially those more advanced in maturation.

Animals↗
PubMed1985

Thyroxine-induced cardiomegaly in rats of different age.

In the present study the effect of thyroxine treatment on the development of cardiomegaly was compared in young (10-day-old) and adult (12-week-old) rats. L-thyroxine was administered subcutaneously in a dose of 1 mg per kg b.w. for 5 days. In young thyroxine-treated rats the heart weight increased by 79% in comparison with the control rats. The number of blood capillaries and muscle fibres per mm2 remained unchanged. The concentration of hydroxyproline was even lower than in control animals. The number of 3H-thymidine-labelled muscle cell nuclei was significantly higher both in the left and right ventricles of thyroxine treated rats. The density of capillaries and muscle fibres was significantly lower in adult rats than in the group of young animals. In adult thyroxine-treated animals the heart weight was higher by 36%, the number of capillaries and muscle fibres as well as the concentration of hydroxyproline was unchanged. Thyroxine induced significant increase in the number of DNA synthesizing nuclei of muscle cells in the left ventricle while the change in the right ventricular myocardium was not statistically significant. The present data indicate that a hyperplastic response of cardiac muscle cells to thyroxine occurs in both ventricles of young rats and also in the left ventricle of adult animals.

Aging↗
PubMed1985

The organization and differentiation of nervous cells in tissue cultures (a minireview).

Single stages of histiotypic formation from dissociated embryonic brain cells are described. The first stage, i.e. primary adhesion, is a phenomenon depending mainly on physicochemical features of the adhesive system. The composition of the membrane glycoprotein coat was studied during membrane regeneration and formation of cellular contacts. At the beginning single terminal sugar components and negative sialic acid residues are distributed non-homogeneously over the membrane according to the ligation of lectins. During the formation of cellular contacts this non-homogeneity progressively disappears, the thickness of the layer is reduced, however, the density of single markers increases. The highest increase of both density and layer thickness during the phase of membranes reparation occurs when the negative surface groups are labelled with cationized ferritin. The sorting out process was studied in mixed cultures as a stage of final specific recognition. It is assumed that the reaggregation of cells is a multistep process depending on maturation of the glycoprotein coat, characterized by multiple cellular adhesion and deadhesion, completed by specific recognition and fixation of recognized cells.

Animals↗
PubMed1985

A cytophotometric and karyometric study of the cardiac muscle cells of young rats exposed to intermittent high altitude hypoxia.

Thirty-day-old rats were exposed to intermittent high altitude in barochamber (7000 m, 4 h per day, 4 exposures) and number of mono- and binucleated myocytes as well as DNA content per nucleus were determined in the right ventricular myocardium. The data indicate enhancement of mitotic division of mono- and binuclear diploid cells in hypoxic animals. Simultaneously, an increase in mononuclear and binuclear tetraploid cells occurred; the latter is probably due to DNA synthesis not followed by mitosis of some binuclear diploid cells.

Altitude↗
PubMed1984

Uptake and transport of lectins from the cerebrospinal fluid by cells of the immature mouse brain.

40 mice (C57BL/6J) 2, 3, 6, and 10 d old were injected intraventricularly with 2% wheat germ agglutinin (WGA) or soybean agglutinin (SBA). The transport of lectins from the ventricular cerebrospinal fluid (CSF) into brain parenchyma was studied by an unlabelled antibody technique ( BORGES and SIDMAN 1982). The granule product of the immunohistochemical reaction was found in the cytoplasm of ventricular ependymal cells, the choroid plexus and meninges in all age groups studied. Penetration of lectins into brain parenchyma was higher in younger animals and at more immature-cell-surrounded parts of lateral and the IVth ventricle. The stain product was dispersed throughout the neuropil excepting cell nuclei. Higher concentration of lectins appeared in nerve cell cytoplasm of some regions of the brain of younger animals (P2 to P3); in 10 d old mice granules of stain appeared in the cytoplasm of PURKINJE cells and pyramidal neurons of the hippocampus. A fiber-like staining, apparent especially in large commissures adjacent to brain ventricles (corpus callosum, fornix hippocampi) in all age groups, suggests that lectins are transported within axons, even at the earliest postnatal ages. Unlike WGA, densely stained glial cells appeared in parenchyma of SBA injected animals, especially of the younger age group (P3 to P6). The results of this study confirm earlier findings that macromolecules within the ventricular CSF can penetrate into brain parenchyma but suggest that the penetration is higher in less mature animals and at the ventricle regions surrounded by less differentiated parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1984

DNA synthesis in the cerebellar Purkinje neurons of early postnatal rats: an extra DNA or a repair process?

DNA synthesis and Feulgen - DNA content in Purkinje neurons were examined in early postnatal rats exposed to cis-dichlorodiammineplatinum II (cis-DDP) and (3H) thymidine. Autoradiographic data revealed a significant although low labelling in control rats on postnatal day 10 to 11; the incorporation deeply decreased after cis-DDP administration. Cytophotometry showed formation of some Purkinje cells with hyperdiploid DNA content in control animals between postnatal day 11 and 16, whereas in cis-DDP treated rats all cells remained diploid. A close correlation between the formation of hyperdiploid Feulgen-DNA nuclei and the incorporation of (3H) thymidine provides new, indirect support for an actual DNA surplus in some Purkinje cells, although the incorporation of some of (3H) thymidine due to an enhanced turnover and or repair of DNA in Purkinje cells of 10 to 11 days old rats is not excluded.

Age Factors↗
PubMed1983

Cell death in the dividing pool of cells in the mouse brain.

A follow up biochemical and autoradiographic study of DNA synthesis and its retention revealed that a great part of newly synthesized DNA disappears from the brain of young adult mice within a few days. This is supposed to be mainly due to the short half-life of a majority of newly formed cells. These data provide further evidence on the redundant cell proliferation taking place in the small pool of brain cell population scattered throughout the parenchyma of the brain of young adult mice.

Animals↗