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V Mares

Publications and source records attributed to V Mares.

At least 55 records · Page 3Linked to original sources
PubMed1992

Spontaneous hemorrhage in the cerebral cortex of immature rats.

We report the presence of spontaneous hemorrhages in the brain of normal neonatal rats. The quantitative evaluation showed that the hemorrhaging was most frequent in 4- to 5-day-old rats. Nearly all the lesions were found in the cerebral cortex of the lateral part of the forebrain hemisphere, particularly in the middle cortical layers. Their average incidence amounted to 6.71 +/- 2.95 per six 5-microns sections from 5-day-old rats. The lesions were nearly absent in the newborn and 7-day-old animals. We suggest that vascular wall immaturity and some extravascular factors, like developmental increase of blood pressure, may account for the perinatal hemorrhaging.

Animals↗
PubMed1992

Accumulation of boron-10 (10B) in cell cultures exposed to mercaptododecaborate (Na2H(11)10B12SH) used for the neutron capture therapy of brain tumors.

Toxicity of mercaptoundecahydro-closo-dodecaborate (MHB, Na2H(11)10B12SH) and accumulation of MHB-derived 10B were studied in E7 neuroblastoma, C6 glioma, HeLa cells and embryonic lung LEP 19 fibroblasts in culture in exponential and stationary phases of growth (2- and 7-day-old cultures, respectively). The pilot study of acute toxicity, performed on C6 glioma cells, showed good tolerance of the drug up to 1000 micrograms/ml (4.8 x 10(-3) M), when cell growth slowed and a small part of the population was lethally damaged (8.3%, 20-h incubation interval). The changes became more extensive and appeared sooner (toward 5 h) at 2000 micrograms MHB/ml (9.5 x 10(-3) M). None of the four cell lines used was found to be affected in gross morphology or growth by 200 micrograms MHB/ml within a 5-day culture interval. When exposed to this dose for 4 h, the amount of 10B accumulated in cell lines at the exponential growth phase ranged from 0.51 to 4.4 ng/micrograms protein; in the stationary cultures of the corresponding cell phenotype, the 10B values were 3 to 10 times lower (0.12-1.2 ng/micrograms protein). Irrespective of the growth phase, the values achieved in C6 glioma cells were several times higher than in the other cell lines. Furthermore, in the glioma cells, particularly in the exponential phase of growth, accumulation of 10B proceeded against the marked concentration gradient. The data provide a new indication for the use of MHB for boron neutron capture therapy of brain tumors.

Animals↗
PubMed1991

Changes in cell cycle and chromatin distribution in C6 glioma cells treated by dibutyryl cyclic AMP.

C6 glioma cells in culture were treated with 1 mM dibutyryl cyclic AMP (Db-cAMP) for 5, 8, 24 and 72 h. The cells were labelled with [3H]-thymidine before either the end, or the beginning, of the Db-cAMP treatment. The cell cycle passage was monitored by the simultaneous determination of DNA content and DNA synthesis in propidium iodide stained autoradiograms. The data revealed an early (t less than or equal to 3-8 h) and moderate inhibitory effect of Db-cAMP on all phases of the cell cycle except mitosis; some cells (2%) were completely blocked in the S phase. Later (8 less than t less than 24-72 h), the cycling of a substantial part of the population became inhibited in G1 phase. Microdensitometric texture analysis of Feulgen-stained nuclei, performed 24 h after administration of Db-cAMP, showed a higher inhomogeneity of the DNA distribution in cell nuclei, caused by the condensation of a part of the chromatin. This may reflect either changes in genome expression taking part in the process of cAMP induced differentiation or transit of some cells into quiescent G0 or S0 phases.

Animals↗
PubMed1991

Thy 1 expression in the brain of nude mice.

The expression and cell distribution of Thy 1 antigen was studied in the brain of both normal and athymic (nude) young adult mice of the BALB/c strain by immunochemistry. In nude animals Thy 1 fluorescence was less intense and less regularly distributed in the molecular layer of the cerebellum and hippocampus. Thy 1 content determined by ELISA was lower by 10-16% in the cerebellum and 20-25% in the olfactory bulbs of nude mice. The total wet weight of the brain was lower by 16% than in control animals; the deficit in body weight ranged from 34-45%. It is supposed that the changes in Thy 1 expression in nude animals are caused mainly by the underdevelopment of late developing brain regions due to thermoregulatory problems and other postnatal strains occurring in the mutants.

Animals↗
PubMed1990

Premitotic DNA synthesis in the brain of the adult frog (Rana esculenta L.): an autoradiographic 3H-thymidine study.

Replicative synthesis of DNA in the brain of the adult frog was studied by light microscope autoradiography. Animals collected during the active period (May-June) and in hibernation (January) were used. In active frogs, 3H-thymidine labelling occurred mainly in the ependymal cells which line the ventricles. The mean labelling index (LI%) was higher in the ependyma of the lateral and fourth ventricles than in the ependyma of the lateral diencephalon and tectal parts of the mesencephalon. In the recessus infundibularis and preopticus the number of labelled cells (LCs) was several times greater than in the lateral parts of the third ventricle. LCs were seen subependymally only occasionally. The incidence of LCs in the parenchyma of the brain was much lower in most regions than in the ventricular ependyma; LCs were mainly small and, from their nuclear morphology, they were glial cells. The LI% reached the highest value in the septum hippocampi and in the nucleus entopeduncularis. In these locations, LCs were larger and closer in size to the nerve cells of these regions. From comparison with data obtained earlier in the brain of mammals, it is evident that the distribution of proliferating cells in the olfactory and limbic system is phylogenetically conservative. The occurrence of pyknotic cells in the same areas which contain LCs, suggests that cell division reflects in part the process of cell renewal observed in mammals. However, proliferating cells could also be linked to the continuous growth observed in non-mammalian vertebrates. In hibernating frogs, LCs and pyknoses were not seen or were found occasionally, which further indicates the functional significance of both processes.

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PubMed1989

Na+, K+-ATPase activity in cultured C6 glioma cells.

Rat C6 glioma cells were cultured for 4 days in MEM medium supplemented with 10% bovine serum and Na+, K+-ATPase activity was determined in homogenates of harvested cells. Approximately 50% of enzyme activity was attained at 1.5 mM K+ and the maximum (2.76 +/- 0.13 mumol Pi/h/mg protein) at 5 mM K+. The specific activity of Na+, K+-ATPase was not influenced by freezing the homogenates or cell suspensions before the enzyme assay. Ten minutes' exposure of glioma cells to 10(-4) or 10(-5) M noradrenaline (NA) remained without any effect on NA+, K+-ATPase activity. Neither did the presence of NA in the incubation medium, during the enzyme assay, influence the enzyme activity. The nonresponsiveness of Na+, K+-ATPase of C6 glioma cells to NA is consistent with the assumption that alpha (+) form of the enzyme may be preferentially sensitive to noradrenaline. Na+, K+-ATPase was inhibited in a dose-dependent manner by vanadate and 50% inhibition was achieved at 2 x 10(-7) M concentration. In spite of the fact that Na+, K+-ATPase of glioma cells was not responsive to NA, the latter could at least partially reverse vanadate-induced inhibition of the enzyme. Although the present results concern transformed glial cells, they suggest the possibility that inhibition of glial Na+, K+-ATPase may contribute to the previously reported inhibition by vanadate of Na+, K+-ATPase of the whole brain tissue.

Animals↗
PubMed1988

A combined method of acetylcholinesterase histochemistry and [3H]thymidine autoradiography: application to neurogenesis of the rat basal forebrain cholinergic system.

Rats labelled with [3H]thymidine on embryonic day 15 were treated postnatally with diisopropylfluorophosphate and 2-3 h later perfused with 10% buffered formalin. Cryostat sections of the basal forebrain were autoradiographed and subsequently stained for acetylcholinesterase (AChE). It was shown that this procedure did not significantly influence either the AChE activity or the silver grains over [3H]thymidine-labelled nerve cell nuclei. The labelling index evaluated in cholinergic forebrain regions (medial septum, diagonal band of Broca, substantia innominata, nucleus basalis of Meynert) indicated a caudorostral gradient of the formation of AChE-containing neurons while formation of non-cholinergic neurons showed a more even pattern.

Acetylcholinesterase↗
PubMed1988

Intranuclear differences in the response of Purkinje cell DNA of the rat cerebellum to bleomycin. A microphotometric and autoradiographic study.

A single dose of the DNA-binding cytostatic agent bleomycin (100 micrograms/g body weight, subcutaneously) was given to 10-day-old rats to study unscheduled repair DNA synthesis in nucleolar and in bulk nuclear chromatin of postmitotic Purkinje neurons. The Feulgen reaction and Hoechst 33342 staining were used for quantitative evaluation of nuclear DNA content and chromatin structure. The repair synthesis of DNA was detected by 3H-thymidine autoradiography. The data showed a lesser staining of Purkinje as well as granule cell DNA by Hoechst 33342 in bleomycin-treated animals than in controls, but there was no difference in staining with the Feulgen reaction. The mechanisms of DNA staining by both cytochemical methods suggest that bleomycin reacted preferentially with AT-rich and single stranded DNA in cerebellar cells in vivo. Weak 3H-thymidine labelling was found in Purkinje cells of both control and treated rats, but in the latter group the labelling was more pronounced near or over the nucleolus. The enhanced unscheduled DNA synthesis in the nucleolar region of Purkinje cells of treated animals may be due to greater damage of DNA in this region or may indicate a greater ability of the nucleolar chromatin to repair its DNA.

Animals↗
PubMed1988

Immunocytochemistry and heterogeneity of rat brain vimentin.

In unfixed cryostat sections of the brains of early postnatal and adult rats, we screened for cells containing vimentin-positive intermediate filaments (VI+-IFs) by applying a panel of four monoclonal antibodies (Mabs VI-01, VI-02, VI-05 and VI-5B3) using indirect immunofluorescence. All of the Mabs stained VI+-IFs in the stromal part of the choroid plexus, in endothelial cells of blood vessels and in meninges in both adult and immature brains, although with varying strength (VI-5B3 and VI-01 stained more strongly than VI-05 and VI-02). In the brain parenchyma of adults, intense staining was mainly localized in ventricular ependymal cells (VI-5B3/VI-01 greater than VI-02/VI-05) and fibrous astrocyte-like cells (FAs). In the immature brain, the ependymal cells were activated in appearance, with evidence of cell enlargement, greater spreading of VI+-IFs within the cytoplasm and more pronounced VI+ cytoplasmic protrusions into the brain parenchyma. VI+-FAs were found near the ependymal and meningeal borders as well as in the white matter tracts of adult brain (VI-5B3/VI-01 greater than VI-05 greater than VI-02). In immature animals, VI+-FAs were less frequently encountered in the forebrain regions, except in and near the subepenydmal layer (in the adjacent parenchyma) as well as in submeningeal layers. Weaker staining was usually elicited by Mabs VI-02 and VI-05. In the cerebellum, Bergmann cell fibers were stained in both age groups. In adults, the most intense fluorescence usually occurred in segments close to the pia (VI-5B3/VI-01 greater than VI-05 greater than VI-02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Damage and repair of the immature rat cerebellum after cis-dichlorodiammineplatinum II (cis-DDP) treatment. An ultrastructural study.

The aim of this electron microscopy study was to further investigate the effects of cis-dichlorodiammineplatinum (cis-DDP) on the cerebellum of the immature rat. Ten-day-old animals were treated with cis-DDP subcutaneously and killed after 1, 7, 15 or 21 days. On postinjection day 1, cis-DDP effects were evident mainly in the external granular layer, with nuclear damage in many dividing cells, while their cytoplasm appeared to be less affected. Some binucleate cells were also present. On the contrary, in postmitotic or more differentiated cells, only cytoplasmic alterations were found. At later stages (postinjection day 7), the frequency of damaged cells in the external granular layer decreased, but there was a cellular deficit in the internal granular layer. Many postmitotic neurons underwent coagulative necrosis. Finally (postinjection days 15 and 21), the cellular deficit was partly compensated for by "reactive" structures, e.g., glial cell fibers, which underwent hypertrophy after initial edema. Moreover, packing densities of Bergmann astrocytes and oligodendrocytes were higher.

Animals↗
PubMed1987

Influence of cis-dichlorodiamineplatinum on glioma cell morphology and cell cycle kinetics in tissue culture.

C6 glioma cells (CCL 107) were cultured for three days and then treated with cis-dichlorodiamineplatinum (cis-DDP) at doses of 0.2-10 micrograms/ml medium. Changes in DNA synthesis and DNA content, as well as morphology of cells and chromatin distribution, were examined from the first post-treatment day onwards. The number of cells labelled with [3H]thymidine, detected autoradiographically, decreased after treatment with 0.2-10 micrograms/ml by approximately one half on post-treatment day 1 and diminished further by the third day after treatment. The labelled cells were entirely absent only after treatment with 10 micrograms/ml, 7 days post-treatment. Mitoses decreased from 1.4-0.6% by post-treatment day 1 and completely disappeared by day 3 (1 microgram/ml). Feulgen cytophotometry and propidium iodide cytofluorimetry revealed accumulation of cells in the S-phase, especially the latter part (0.5 and 1.0 micrograms/ml, post-treatment day 1) and subsequently also in G2 phase (post-treatment day 3). Incomplete cyto- and karyokinesis in some cycling cells was indicated by an increased number of binucleate cells and nuclei of higher ploidy classes. Labelled cells with intermediate DNA values were, on average, labelled less intensively, as was revealed by simultaneous measurements of DNA content and [3H]thymidine incorporation. Some cells displayed reduction in grain density over heterochromatin clumps. This would be in agreement with the late S-phase block of DNA replication. After post-treatment day 3 the density of cells in cultures was substantially lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Regional differences in protein and glycoprotein synthesis and their processing in the mouse brain as revealed by the incorporation of [3H]proline, N-6-[3H]acetyl-D-glucosamine and [3H]fucose.

The incorporation rate of [3H]fucose, N-6-[3H]acetyl-D-glucosamine and [3H]proline has been compared in five regions of the mouse brain on postnatal day 6. The olfactory bulbs and the cerebellum showed a prevalence of incorporation of [3H]fucose over other brain regions. Less expressed, but still well evident regional differences were observed in [3H]proline incorporation while the incorporation of N-6-[3H]acetyl-D-glucosamine was almost equal in all brain regions. The regional differences were also apparent after considering an actual pool of free isotopes in the individual regions. Gel electrophoresis of [3H]fucose-labelled membrane fraction showed that the higher incorporation of [3H]fucose in the olfactory bulbs is partly due to higher synthesis of low molecular weight glycoproteins, especially in the molecular range of 30,000. The data showed that the protein synthesis and fucosylation, and/or a fast transport of the corresponding molecules, varies more within the brain than the incorporation of N-6-[3H]acetyl-D-glucosamine and possibly also than the "core" part of glycan molecule synthesis.

Acetylglucosamine↗
PubMed1987

Pionic carbon/oxygen capture ratios in blood and muscle tissue of pig.

The pionic carbon/oxygen capture ratio for the blood and muscle tissue of a pig was measured using an intrinsic Ge detector in order to investigate possible explanations for an enhanced lesion observed in the autopsy of pion-irradiated patients. Pure iron was also irradiated in order to determine the energies and intensities of pionic x-rays from iron. It was expected that some of them originated from haemoglobin and could be observed in the spectrum for a blood sample. TE plastic (Shonka A-150) and Lucite were also investigated for comparison with other work.

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