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V Baran

Publications and source records attributed to V Baran.

24 records · Page 2Linked to original sources
PubMed1993

Immunolocalization of DNA in preimplantation mouse embryos.

Distribution of embryonic DNA in mouse preimplantation embryos was studied by the immunoelectron microscopic method with colloidal gold. The embryos (one-cell, early or late two-cell, four-cell) were sampled separately, and immunogold labelling has been performed on thawed ultrathin cryosections. Condensed chromatin blocks were labelled very intensively. DNA labelling was predominantly visible over peripheral chromatin blocks and over small patches of chromatin localized throughout the nucleus of one-cell embryo. DNA distribution appeared to be more extended in the whole nucleus of early two-cell embryo. A few labelled chromatin clumps were observed to be associated with prenucleolar body (nucleolar precursor body--NPB) in this stage. Convex-shaped electron-light areas (fibrillar centres?) were found at the periphery of NPB in the late two-cell stage. These areas were labelled by scattered individual gold particles. In reticulated nucleolar regions (detected in four-cell embryos) immunolabelling appeared as individual gold particles present over the periphery of areas with loosely arranged material (fibrillar centres) surrounded by a denser component (dense fibrillar component). These consecutive changes are correlated with nucleologenesis and with the onset of transcriptional activity. We conclude that at the onset of nucleolar transcriptional activity condensed chromatin does not penetrate the NPB of mouse two-cell embryo.

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PubMed1993

Subdiabetogenic streptozocin treatment impairs preimplantation development of mouse embryos.

To estimate the significance of insulin in the regulation of preimplantation embryo growth, female mice received a single subdiabetogenic dose of streptozocin (65 mg/kg intraperitoneally) 8-11 days or 14-17 days before fertilization. Mean glycaemia levels and the number of embryos per mouse did not differ significantly between the streptozocin-treated and control groups. Morphological analysis of preimplantation embryos collected on day 3 of pregnancy revealed significant changes in the distribution pattern of preimplantation embryo stages recovered from streptozocin-treated females. Continuous insulin treatment of streptozocin-treated mice improved the impaired development of preimplantation embryos only in short-lasting experiments. After a long subdiabetic period (14-17 days) the incidence of degenerated embryos was increased in both streptozocin-treated groups. It can be concluded that the subdiabetic state in female mice impairs preimplantation embryo development which could partly be prevented by insulin treatment.

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PubMed1993

[Electron microscopy immunolocalization of ribosomal ribonucleoproteins using autoantibodies from patients with systemic lupus erythematosus].

Serum of patients against rRNP was tested by Western blot method. Four ribonucleoproteins (15, 16, 36 and 38 kDa) specifically reacted with the antiserum used. The autoantibodies were used for immunolocalization of antigenic structures by immunogold method on ultrathin cryosections of hepatocytes, cumulus cells of antral follicle and spermatocytes. Mice and hamsters were used. The cytoplasm appeared to be labelled most intensively. Gold particles were loosely arranged in the cytoplasm (cumulus cells) or they were associated with endoplasmatic reticulum (hepatocytes). Nucleoli were labelled by a lower incidence of the marker. Gold particles were found over the dense fibrillar component bordering on the granular component. In the cytoplasm individual gold particles were observed. (Fig. 7, Ref. 31.).

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PubMed1992

Immunocytochemical localization of cyclin/proliferating cell nuclear antigen (PCNA) in fertilized eggs of mice.

Immunolocalization of cyclin/PCNA (proliferating cell nuclear antigen) was performed with monoclonal antibody using immunogold methods on ultrathin cryosections of fertilized mouse eggs. Immunolabeling in pronuclei was checked 20, 22, 24 and 26 h after HCG injection. A relation between onset of pronuclei migration (early S-phase) and appearance of colloidal particle clusters was found. Afterwards, (mid S-phase) the increase of labelling and the localization of cyclin/PCNA were found throughout the pronuclei, except in the nucleolar bodies. Lower labelling appeared at the time of close reciprocal pronuclei contact (late S-phase). It is concluded that bulk and distribution of cyclin/PCNA in pronuclei is closely related to the progression of first interphase after fertilization.

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PubMed1986

[An intramammary implant in the prevention of infectious mastitis in cows].

A sterile polyethylene device was introduced in the milk cistern of two mammary quarters of forty dairy cows. The cows were divided into three groups according to the length of exposure of the device in the cistern (3 days, 14 days, 365 days). The somatic cell counts were studied for a year in the first 10 ml fraction of milk and an increase in the somatic cell counts was found in the quarters having the intramammary device, as compared with the control quarters (having no devices). This difference was marked during lactation and prior to the onset of drying off. For the reduction in the frequency of occurrence of new natural intramammary infections, the activity of the device against S. aureus was limited and no activity against S. agalactiae was proved. The proportions of polymorphonuclears, round-cell elements and macrophages were histologically studied and compared for the udder quarters with and without the intramammary body in correlation with the time of exposure of the device to the milk cistern milieu. The most marked differences in favour of the udder quarters with the intramammary device were recorded in the alveoli containing more cells with a significant proportion of polymorphonuclear leucocytes. Small differences were found in the interstitial and subepithelial zone of the milk cistern. The activity of acid and alkaline phosphatase and adenosine triphosphatase was histochemically determined in the tissue structures of the udder and was found not to change under the influence of the device. Leucocytes and macrophages adhering to the surface of the body were observed under scanning electron microscope.

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