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Biomedical subjects

D Raveh

Publications and source records attributed to D Raveh.

71 records · Page 4Linked to original sources
PubMed1989

Successful splenectomy in May-Hegglin anomaly: report of a case with platelet kinetic studies.

Bleeding diathesis is not necessarily one of the conspicuous and serious characteristics of the macrothrombocytopenic syndromes, which include the May-Hegglin anomaly. Nevertheless, occasionally prolonged bleeding time may endanger organs or even life. We report a case of a young girl with severe thrombocytopenia due to May-Hegglin anomaly, who was facing blindness because of intraocular haemorrhages. Being unable to intervene in the pathogenesis of the disease, we performed splenectomy after proving splenic sequestration of platelets. This procedure allowed the performance of a successful bilateral vitrectomy.

Blood Platelets↗
PubMed1989

Analysis of the HO-cleaved MAT DNA intermediate generated during the mating type switch in the yeast Saccharomyces cerevisiae.

A galactose-inducible HO gene was used to induce mating type switching in heterothallic Saccharomyces cerevisiae cells arrested in G1, in rad52 mutants defective in DNA damage repair, and in cells lacking the donor cassettes. The HO-cleaved MAT intermediate is stable over significant lengths of time, i.e. HO cleavage is not coupled to the subsequent gene conversion event. The in vivo cleavage site was mapped to single base resolution by primer extension experiments on total genomic DNA. Cells arrested in G1 with alpha-factor switched mating type thus demonstrating that switches can occur in the absence of replication of the genome. rad52 mutants did not produce MAT DNA of the opposite mating type indicating that the block is prior to the gene duplication stage of the switch. In strains in which the HM donor cassettes are deleted the cut MAT DNA was degraded after induction of the HO gene.

Alleles↗
PubMed1987

Thymoma presenting as a superior vena cava syndrome remission following therapy.

A 45-year-old male developed myasthenia gravis 8 years ago. He received prednisone for 3 years, and resumed complete clinical remission. Five years later, he was admitted with obstruction of the superior vena cava. Invasive thymoma was diagnosed by chest X-ray and an open lung biopsy. Radiation followed by combination chemotherapy with cyclophosphamide, vincristine, and prednisone induced a complete remission. The patient remained disease-free for more than 20 months after the first admission to our department. To the best of our knowledge, superior vena cava syndrome as the presenting symptom of thymoma has never been reported previously.

Combined Modality Therapy↗
PubMed1987

Shigella sonnei myocarditis.

A 19-year-old male was admitted to our department because of high fever, abdominal pain, and diarrhea. Electrocardiogram (ECG) on admission revealed diffuse ST-T changes which persisted for 5 days. Stool culture grew Shigella sonnei. We conclude that the infection with Shigella sonnei was the cause for these findings which were most probably due to myocarditis. To the best of our knowledge myocarditis as a complication of shigella infestation has never been reported.

Adult↗
PubMed1987

Detection of guinea pig cytomegalovirus nucleic acids in cultured cells with biotin-labelled hybridization probes.

Biotin labelled hybridization probes prepared from recombinant plasmids containing segments of the guinea pig cytomegalovirus (GPCMV) genome were used to detect GPCMV nucleic acids in guinea pig cells by in situ hybridization. The time course of GPCMV infection was assessed in two cultured cell types, guinea pig embryo (GPE) cells and 104C1 cells, a transformed and cloned guinea pig cell line. Detection of GPCMV nucleic acids was accomplished in both cell types with individual GPCMV DNA fragments and with mixtures of GPCMV DNA fragments. When compared to other established methods of GPCMV detection, the method of in situ hybridization enabled the detection of a higher percentage of positive cells early during the course of the infection. In addition, differences in the replication cycle of GPCMV in the two cultured cell lines could be demonstrated. These findings will facilitate future studies of GPCMV tissue tropism in vivo.

Animals↗
PubMed1985

Glycogen metabolism and the nuclear envelope-annulate lamella system in the early chick embryo.

The intracellular sites of glycogen degradation in the mid to late uterine chick embryo were determined by cytochemical localization of glucose-6-phosphatase at the ultrastructural level. Enzyme activity was found between the two membranes of the nuclear envelope, in the annulate lamellae and in specialized glycogen-containing membrane scrolls. Annulate lamellae and glycogen scrolls were most frequent during the stages of intensive glycogen degradation. Annulate lamellae appear to be formed from the nuclear envelope. During the early post-laying stages annulate lamellae disappeared and were replaced by endoplasmic reticulum that appeared initially in scroll-like formations.

Animals↗
PubMed1984

The synaptonemal complex as part of the nuclear matrix of the flour moth, Ephestia kuehniella.

A nuclear matrix fraction was prepared from ovaries of the achiasmatic flour moth, Ephestia kuehniella, by removal of the chromatin, using detergent treatment of homogenized ovaries or dissected ovary tips followed by DNase digestion and high salt extraction. Removal of DNA and histones from the nuclei was demonstrated by Feulgen staining and polyacrylamide gel electrophoresis (PAGE), respectively. By light microscopy, ribbon-like structures similar in dimension to the synaptonemal complex were observed in the oocyte after digestion of the chromosomes. Electron microscopic examination of matrix preparations of pachytene cells showed a defined synaptonemal complex structure with both lateral and central elements. Such structures were not found in either the fully differentiated nurse cells or in follicle cells which were exposed to the same preparative technique concurrently. However, in early post-pachytene nurse cells the typical polycomplex structures, formed in these cells from the synaptonemal complex, were found in nuclear matrix preparations. The results suggest an association of synaptonemal complexes with the nuclear matrix.

Animals↗
PubMed1983

A microtiter plate assay for the selection of 6-thioguanine-resistant mutants in Chinese hamster V79 cells in the presence of phorbol-12-myristate-13-acetate.

6-Thioguanine-resistant mutants can be efficiently recovered from Chinese hamster V79 cells incubated at high cell densities in microtiter plates (10(3)-10(4) cells/0.2 ml growth medium/0.4 cm2) when selected with 30 microM 6-thioguanine and 0.1 microgram/ml phorbol-12-myristate-13-acetate, an inhibitor of metabolic cooperation among V79 cells. Mutant frequencies in the microtiter plates were calculated from a direct count of mutant colonies. After treatment of the V79 cells with the carcinogen benzo[a]pyrene in a fibroblast-mediated assay, the mutation frequencies determined with the microtiter assay system were quantitatively similar to those obtained with a conventional procedure in which selection with 6-thioguanine was performed in petri dishes. The mutagenic activities of 3 polycyclic aromatic hydrocarbons (activated in the cell-mediated assay) were assessed with the microtiter plate selection procedure. The active carcinogen benzo[a]pyrene at 1 microgram/ml yielded about 100 mutants per 10(5) colony-forming cells. The same dose of a less active carcinogen, cyclopenta[c,d]pyrene, yielded about 20 mutants per 10(5) colony-forming cells, and benz[a]anthracene, not an active carcinogen, was inactive as a mutagen at all doses tested. Because of the small requirements for growth medium and tissue culture vessels compared with other assays, this microtiter plate assay can serve as an inexpensive system for detecting the mutagenic activity of environmental chemicals in mammalian cells.

Animals↗
PubMed1983

Separation of human lymphocytes on Ficoll-Paque gradients: stimulation of cells and depletion of a concanavalin-A responsive radioresistant subpopulation.

A subpopulation of human lymphocytes separated on Ficoll-Paque gradients showed an ultrastructural phenotype characteristic of stimulated cells. Thymidine incorporation was increased fivefold compared with unseparated (Buffy coat) controls. The Ficoll-Paque separated lymphocytes were more sensitive to gamma radiation than unseparated lymphocytes and showed a decreased capability to undergo transformation in response to concanavalin A. Transformation in response to phytohemagglutinin and pokeweed mitogen was the same as for unseparated control lymphocytes. These results are interpreted as the selective depletion of a Con A-responsive T-cell fraction by Ficoll-Paque separation.

Cell Separation↗
PubMed1982

Cell-mediated mutagenesis and tumor-initiating activity of the ubiquitous polycyclic hydrocarbon, cyclopenta[c,d]pyrene.

The ubiquitous polycyclic aromatic hydrocarbon (PAH), cyclopenta[c,d]pyrene (CPP), was tested to determine its mutagenicity for 6-thioguanine and ouabain resistance in Chinese hamster V79 cells and its tumor-initiating activity in the skin of the tumor susceptible Sencar mice. The potent carcinogen/mutagen, benzo[a]pyrene (BP), was included for comparison. Inasmuch as V79 cells do not metabolize PAHs, mutagenesis was tested both in the presence and in the absence of X-irradiated golden hamster embryo fibroblasts capable of metabolizing PAH. Neither CPP nor BP showed mutagenicity for V79 cells in the absence of the embryo cells. In the presence of these cells (in the cell-mediated assay) both PAHs elicited, in a dose dependent manner, a cytotoxic and mutagenic response in V79 cells. CPP was however less active than BP in inducing both of these responses. At the optimal expression time and at the dose range of 0.1-1 microgram/ml, CPP induced 2-8 6-thioguanine resistant mutants per 10(5) colony forming cells compared to 9-50 mutants induced by BP. Similarly, these doses of CPP induced 1-9 ouabain resistant mutants per 10(6) colony forming cells compared to 7-75 mutants induced by BP. CPP was also active in initiating skin tumors in approximately 60% of the mice at 200 micrograms, the highest dose tested. BP was more efficient in tumor initiation and yielded a similar response with 10 micrograms. These results indicate that CPP and BP elicit, in the cell mediated assay, a mutagenic response similar to the activity of these PAH in the skin of Sencar mice.

Animals↗
PubMed1979

Glycogen metabolism in the prelaid chick embryo.

Glycogen metabolism has been studied during the development of the early chick embryo, at the cytochemical and ultrastructural levels. Two waves of glycogen synthesis and breakdown have been found. In the first, free clusters of glycogen particles are synthesized at late oogenesis. These clusters are found later in invaginations of the membrane of vesicles containing a floccular material (FLOV). The glycogen clusters are degraded there during ovulation and the first hours in the oviduct. The second wave of glycogen synthesis begins before cleavage, reaching a maximum at mid-uterine age. This second wave occurs in another type of vesicle (GLYV), which eventually disintegrates releasing free clusters of glycogen granules. This glycogen is degraded in membranous structures containing a floccular material, as in the first wave of degradation. The degradation ends at the late uterine stages, and at the same time numerous ribosomes are formed. This period corresponds to area pellucida formation, which probably depends on the energy liberated during the second wave of glycogen degradation.

Animals↗
PubMedDate not supplied

Comparison of peritoneal fluid culture results from adults and children undergoing CAPD.

BACKGROUND: Peritonitis is a common complication in patients with end-stage renal disease treated by continuous ambulatory peritoneal dialysis (CAPD). Empirical treatment is based on the organisms that are most frequently isolated and their susceptibilities. OBJECTIVE: To analyze and then compare peritoneal fluid culture results from adult and pediatric patients on CAPD, with respect to micro-organisms and antimicrobial susceptibilities. DESIGN: Three-year retrospective review of peritoneal fluid cultures from adults and children on CAPD. RESULTS: We isolated 481 organisms from 378 peritoneal fluid specimens, collected from 135 patients (45 children, 90 adults). There were 191 episodes of peritonitis in children (mean 4.2+/-3.5, range 1 - 15) compared to 187 in adults (2.1+/-1.9, range 1 - 10) (p< 0.001). Two or more episodes occurred in 30 of 45 children (67%) compared to 33 of 90 adults (37%) (p < 0.001).The number of different organisms/patient as well as the total number of isolates/patient were significantly greater in children (respectively, 2.8+/-2.3, range 1 - 12; and 5.3+/-5.2, range 1 - 27) than in adults (2.0+/-1.3, range 1 - 6; and 2.7+/-2.4, range 1 - 10) (p< 0.005). After Staphylococcus epidermidis, S. aureus was the most frequently isolated organism, occurring in 18% of episodes in adults and 12% of episodes in children (p< 0.01). Twenty-two of 33 fungal isolates (67%) in children were Candida parapsilosis compared to 3 of 24 (12%) in adults (p < 0.001). Subanalysis of multiple episodes revealed that Pseudomonas and Candida occurred significantly more often in children (p< 0.01), whereas S. aureus occurred more often in adults (p< 0.001). In polymicrobial episodes S. epidermidis occurred more often in adults (p < 0.05). Significant differences in susceptibilities to ampicillin, ceftriaxone, chloramphenicol, and gentamicin were found between children and adults (p< 0.05 - 0.001). CONCLUSIONS: CAPD-associated peritonitis occurs significantly more often in children than adults. Significant differences in microbial etiology and susceptibilities were found between pediatric and adult patients. Each dialysis unit should periodically analyze peritoneal fluid culture results from its CAPD patients. These data can then be used for optimization of empirical antimicrobial therapy of peritonitis.

Adult↗