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Biomedical subjects

Y Daskal

Publications and source records attributed to Y Daskal.

At least 19 recordsLinked to original sources
PubMed1985

AIDS prodrome in an apparently normal man following coronary artery bypass: new significance of postoperative bleeding.

An otherwise healthy, apparently normal 45-year-old man underwent a triple coronary artery bypass procedure, complicated only by modest postoperative bleeding. He had received aspirin and dipyridamole preoperatively, and was given 1 unit of packed red cells and 4 units of fresh frozen plasma on the day of operation. Fifteen months later, malaise and diffuse lymphadenopathy developed. Lymph node biopsy and immune studies were characteristic of the AIDS prodrome. This experience emphasizes the need for control of bleeding and the avoidance of blood products wherever possible.

Journal Article↗
PubMed1984

Histological and ultrastructural changes in breast adenocarcinoma after treatment with plasma perfused over immobilized protein A.

Administration of plasma perfused over Protein A immobilized in collodion-charcoal produced focal acute tumor necrolytic reactions in breast adenocarcinomas. With repeated procedures, objective tumor regressions were observed in four of the first five consecutive patients treated. Within 4 to 48 hr after treatments, tumors became hyperemic and edematous, often with the appearance of focal vesicles. Microscopic and ultrastructural evaluation demonstrated a spectrum of lesions in cytoplasm and nucleus of tumor cells indicative of lethal and sublethal changes. With further treatments, more pronounced degenerative changes in individual tumor cells, tumor nodules, and intervening stroma were apparent. Furthermore, increased luminal and abluminal vesiculation of endothelial cells of postcapillary venules adjacent to tumor nodules was noted. With continued treatments at intervals of 2 to 3 days, some tumor sites showed focal mononuclear cell infiltration, and at the conclusion of plasma perfusion treatments previously ulcerated tumor foci were replaced by granulation tissue. These data suggest that several cytotoxic and inflammatory mechanisms are activated simultaneously or in succession and may account for the tumoricidal effects noted following repeated plasma perfusions.

Adenocarcinoma↗
PubMed1983

Ultrastructural and purification studies on human tumor nucleolar antigens and nucleolar particles.

The presence of common nucleolar antigens in a broad array of human malignant tumors has led to several lines of investigations. In addition to studies on an increasing number of benign and malignant neoplasms with a variety of antibodies designed to statistically evaluate the presence of nucleolar antigens, purification procedures and chemical analyses are being used to characterize the specific antigens. The localization of the nucleolar antigens in HeLa cells was studied by the postembedding immunoelectron microscopic procedure employing rabbit antibodies to nucleoli or nuclear Tris extracts of these cells. The products of the peroxidase-antiperoxidase complexes visualized by the reaction with diaminobenzidine in nucleoli were mainly found in the nucleolonemas which contain the dense nucleolar RNP components. When these nucleoli became compact after treatment of HeLa cells with adriamycin, the distribution of the immunoreactive products was altered along with distribution of the dense nucleolar components. The human nucleolar antigens were mainly localized to nucleolar regions containing the nucleolar RNP components. Improved purification of the antigens made it possible to provide a satisfactory amino acid analysis of one pI 6.3 antigen. Interestingly, some of the nucleolar antigen was found in miniparticle undescribed until now.

Amino Acids↗
PubMed1981

DNA supercoiling, shortening, and induction of single-strand regions by cis-diamminedichloroplatinum(II).

cis-Diamminedichloroplatinum(II) was found to bind to covalently closed circular supercoiled, covalently closed circular nonsupercoiled, and single-strand broken relaxed PM2 DNA and induce different types of DNA conformational changes. Using Kleinschmidt's technique, it was found that binding of cis-diamminedichloroplatinum(II) decreased the DNA length to 75% of the original single-strand broken relaxed DNA without inducing superhelical conformational changes. cis-Diamminedichloroplatinum(II) also shortened the length of covalently closed circular nonsupercoiled DNA before a supercoiled conformation was generated. Single strand-specific nucleases were used to detect drug-induced DNA structural alterations. Local single-strand regions or regions of denaturation were detected by S1 nuclease from Aspergillus oryzae and by BAL-31 nuclease from Alteromonas espejiana BAL-31. The single-strand regions or local denaturation regions do not seem to be related to or caused by DNA superhelical conformational changes since they were detected at drug concentrations at which no significant DNA superhelical turns were found. DNA shortening, superhelical conformational changes, and local denaturation regions can be explained by the previously proposed "DNA intrastrand cross-linking" model (Stone et al., J. Mol. Biol., 104: 793-801, 1976).

Cisplatin↗
PubMed1980

Characterization of a nucleolar residue fraction that specifically transcribes preribosomal RNA.

Treatment of isolated nucleoli with Sarkosyl (2%) dissociated 99.5% of the proteins. The residual DNA-protein complex contained the endogenous transcriptional activity which had a high fidelity of RNA synthesis. Electron microscopic analysis of this residue fraction showed the presence of 150-200A diameter protein globules present along the length of some of the DNA fibers. SDS-polyacrylamide gel electrophoretic analysis of the proteins of the complex indicated that the subunits of purified RNA polymerase I were only a minor component of this complex. Associated with the complex were the U3 and 5S RNA.

Animals↗
PubMed1980

Morphological effects of mitomycin C administered intravesically to normal mice and mice with N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide-induce bladder neoplasms.

The intravesical administration of mitomycin C to normal and N-[4-(5-nitro-2-furyl)-2-thiozolyl]formamide-induced bladder tumor-carrying mice at initial concentrations of 2 and 5 mg/ml for 2 hr resulted in marked morphological effects including cytoplasmic and nuclear abnormalities and disruption of surface architecture. Tumors cells and normal urothelial cells were sensitive to the effects of mitomycin C. These effects were limited to epithelial cells.

Animals↗
PubMed1979

Subcellular localization of DNA-binding protein BA by immunofluorescence and immunoelectron microscopy.

Nonhistone protein BA has been shown to decrease in amount in the chromatin of growth- stimulated normal rat liver (Yeoman et al. 1975. Cancer Res. 35:1249-1255) and in mitogen-stimulated normal human lymphocytes (Yeoman et al. 1976. Exp. Cell Res. 100:47- 55.). Subsequently, protein BA was purified and was shown to prefer to bind to double- stranded A-T-rich DNAs (Catino et al. 1978. Biochemistry. 17:983-987.). Immunization of rabbits with highly purified protein BA has resulted in the production of a specific antibody. A specific immunoreactivity for chromosomal protein BA has been demonstrated by immunoelectrophoresis and double antibody immunoprecipitation analysis with rabbit anti-BA immunoglobulin and IgG fractions. Light microscope examination of normal rat liver crysections by the indirect immunofluorescence procedure has demonstrated a cytoplasmic as well as a nuclear localization for protein BA with a pronounced perinucleolar fluorescence. Immunoelectron microscopy employing the peroxidase antiperoxidase method of antigen localization has confirmed the immunofluorescence data and has show a heterochromatin localization for protein BA. The relationship of the localization of protein BA to gene control in quiescent cells or to configurations of heterochromatin as well as the marked reduction in the amounts of protein BA which occur in stimulated growth states remains to be defined.

Animals↗
PubMed1979

Acute ultrastructural effects of the antitumor antibiotic carminomycin on nucleoli of rat tissues.

Male Sprague-Dawley rats were treated with carminomycin i.v. in doses ranging from 1 to 40 mg/kg. Within 1 hr after the administration of carminomycin, 20 mg/kg, nucleoli of cardiac and skeletal muscle cells were segregated, while nucleoli of liver parenchyma cells were unaffected. Three and one-half hr after drug administration, cardiac muscle nucleoli reverted to normal ultrastructure. However, some skeletal muscle cell nucleoli were still segregated. Following treatment with carminomycin, 10 mg/kg, no significant ultrastructural changes were observed. These results demonstrate that at sufficiently high doses carminomycin induces ultrastructural lesions in nucleoli of both cardiac and muscle cells. The dose of carminomycin required to produce nucleolar segregation in cardiac and skeletal muscle is 6 times greater than the dose of Adriamycin (3.5 mg/kg) required to induce equivalent alterations.

Animals↗
PubMed1979

Perichromatin granules in the liver nuclei after isolation of hnRNP (informofer) particles.

The influence of the extraction of hnRNP (informofer) particles on the ultrastructural appearance of the perichromatin granules was studied. The extraction of hnRNP particles was carried out by SAMARINA's procedure from the rat liver nuclear fraction. The extraction did not change the numbers and the general ultrastructural features of perichromatin granules. It is therefore unlikely that the perichromatin granules are the morphological representatives of storaged or transported hnRNA.

Animals↗
PubMed1979

Silver staining of nucleolar granules in tumor cells.

With the aid of a simple silver-staining procedure, large numbers and unusual arrays of nucleolar argyrophilic granules were found in Novikoff hepatoma, KB, and HeLa cells. Some of these arrays consisted of linearly arranged discrete granules, and others were in two to three rows each containing three to five granules. Corresponding formations were not found in either the normal or regenerating liver nucleoli which contained an argyrophilic network in which the dark granules were apparently associated with the less dark argyrophilic fibrils of a reticulum. The nucleolar argyrophilic granules were readily identifiable in the separated daughter nuclei of the tumor cells in telophase, suggesting that the increased nucleolar activity of the G1 phase begins in these cells even before cell division has been completed.

Animals↗