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Biomedical subjects

R Weber

Publications and source records attributed to R Weber.

At least 19 recordsLinked to original sources
PubMed1979

Enrichment and characterization of the DNA coding for vitellogenin in Xenopus laevis.

Purified vitellogenin mRNA of Xenopus laevis was incubated with mechanically sheared DNA in high concentrations of formamide and the resulting R-loops (i.e. RNA . DNA hybrid fragments) separated from the bulk DNA by caesium chloride buoyant density centrifugation. Hybridization with 125I-labeled vitellogenin mRNA revealed a 15--30-fold enrichment of the DNA coding for vitellogenin. Restriction analysis of the R-loop-enriched DNA demonstrated that all known endonuclease HindIII fragments coding for vitellogenin of unfractionated Xenopus DNA were also present in the enriched material, including the specific fragments for the oligo(A)-containing segment of the RNA. Comparison of these restriction data with the structure found in cloned vitellogenin cDNA, indicates the presence of at least one intervening sequence in the genomic DNA coding for vitellogenin.

Animals↗
PubMed1979

Vitellogenin in Xenopus laevis is encoded in a small family of genes.

Vitellogenin, the yolk protein precursor, is produced in X. laevis liver from a 6.3 kilobase (kb) mRNA. Sequences of this mRNA have been transcribed into cDNA and cloned in E. coli. Some properties of 21 of these cloned DNAs, ranging in size from 1 to 3.7 kb, have been reported by Wahli et al. (1978b). This paper reports restriction endonuclease mapping, cross hybridization, heteroduplex mapping in the electron microscope and heteroduplex melting experiments with these DNAs. We conclude that the cloned DNAs fall into two main groups of sequences which differ from each other in approximately 20% of their nucleotides. Each main group contains two subgroups which differ from each other by about 5% sequence divergence. By hybridizing cloned DNAs with restricted genomic DNA, we showed that sequences corresponding to all four sequence groups are present in a single animal. Furthermore, we have obtained tentative evidence for the presence of large intervening sequences in genomic vitellogenin DNA. Analysis of R loop molecules demonstrated that all four sequences are present in the vitellogenin mRNA population purified from individual animals. While some alternate explanations are not entirely excluded, we suggest that vitellogenin is encoded by a small family of related genes in Xenopus.

Animals↗
PubMed1978

Medicaid-funded private psychiatric care in New York City. The role of foreign-trained physicians.

Data were obtained from the tax records and the Professional Registry maintained by the New York City Department of Health as well as from the Biographical Directory of the American Psychiatric Association to determine which psychiatrists were providing care under the Medicaid Program and how they compare with the pool of psychiatric practitioners in New York City. The data reveal that psychiatrists educated in foreign medical schools provide disproportionately more care to Medicaid recipients than would be anticipated from their numbers, and are a majority of those who received more than +30,000 in payments in 1976. Furthermore, these psychiatrists account for 80 per cent of those delivering care at the two largest "shared health facilities," commonly referred to as "Medicaid mills." These findings indicate that although the Title XIX Program has facilitated the access of the poor to the private psychiatric sector, in New York City their access is biased toward treatment by foreign-educated psychiatrists.

Foreign Medical Graduates↗
PubMed1978

[Comparison between cytochemical and gelelectrophoretic demonstration of acid phosphatases from leukocytes (author's transl)].

The cytochemical and gelelectrophoretic demonstration of acid phosphatases with substrates alpha-naphthyl phosphate and naphthol AS-BI phosphate and with couplers fast garnet GBC and hexazotized pararosanilin is described. Cytochemically best results are achieved wit naphthol AS-BI phosphate and pararosanilin, electrophoretically however with alpha-naphthyl phosphate and pararosanilin. This discrepancy ist explained by a different substrate affinity and membrane penetration of substrates.

Acid Phosphatase↗
PubMed1978

Cryopathic gangrene with an IgM lambda cryoprecipitating cold agglutinin.

Immunochemical and serologic studies of cold agglutinis in patients with chronic cold agglutinin disease (CCAD) have shown the almost exclusive occurrence of IgM kappa antibodies with specificity for the I antigen of red cells. An unusual subgroup of patients has been delineated in which the cryoprotein is IgM lambda, frequently lacks I specificity and often cryoprecipitates. Studies of such a protein from a patient with an unusual array of immunoproliferative disorders including Grave's disease with exophthalmos and Waldenstrom's macroglobulinemia indicate that the cryoprecipitating and cold agglutinating properties probably derive from the sam protein. The occurrence of this type of antibody should suggest the presence of a more aggressive lymphoproliferative disorder than simple CCAD.

Adult↗
PubMed1978

Estradiol-induced accumulation of vitellogenin mRNA and secretion of vitellogenin in liver cultures of Xenopus.

Explants of male Xenopus liver maintained in a serum-free culture medium respond to stimulation by 2 X 10(-8) M 17beta-estradiol with an increasing rate of accumulation of vitellogenin mRNA, as revealed by hybridization of cDNA to the total cytoplasmic RNA extracted from the cultures. A similar response is observed for secretion of 32PO4-labeled vitellogenin into the culture medium. The in vitro response is improved in liver tissue of prestimulated animals, and by adaptation of liver explants to the culture medium prior to hormone treatment, but attains only about 10% of the in vivo response. Since essential features of the in vivo response are maintained in liver explants, organ culture appears suitable for investigating initial events of estradiol action leading to enhanced synthesis of vitellogenin.

Animals↗
PubMed1978

Electron-microscopic demonstration of terminal and internal initiation sites for cDNA synthesis on vitellogenin mRNA.

cDNA synthesized on purified vitellogenin mRNA from Xenopus liver was hybridized to the template in formamide/urea at 22 degrees C to avoid degradation of the RNA. The hybrids formed were visualized by spreading for electron microscopy. Contour length measurements proved that most of the RNA molecules in the hybrids were still intact showing the expected molecular weight of 2.3 x 10(6). The hybridized cDNA corresponded on the average to 12% of the RNA length. In about 80% of the molecules the cDNA was located at one end. Since cDNA synthesis was primed by oligo(dT), the terminal duplex region marks the 3' end of the vitellogenin mRNA molecule. Internal duplex regions were mainly located at a specific position starting about 2800 nucleotides from the 3' end. Since the cDNA hybridizing at the internal position could specifically be synthesized on a vitellogenin RNA fragment isolated on poly(U)-Sepharose as an oligo(A)-containing RNA, we conclude that cDNA synthesis is not only initiated by the poly(A) of the 3' end, but also by a specific internal sequence.

Animals↗
PubMed1977

[Isoenzyme pattern of acid phosphatase in epstein-barr-virus-DNA positive permanent growing lymphoid cell lines (author's transl)].

The expression of acid phosphatases is cytochemically one of the most important features in permanent growing B-cell-lines. In few cell lines acid phosphatase is resistant against tartrate. Tartrate resistant isoenzyme 5 with components a and b can be demonstrated in monocytes, lymphocytes, chronic lymphatic leucemic cells and especially in hairy cells as well as in cell lines derived from a healthy donor. Fractionation of acid phosphatase by gelelectrophoresis in separated lymphocytes demonstrates especially isoenzyme 3, in separated macrophages isoenzyme 4. Isoenzyme 4 could not be detected in several cell lines. It is therefore concluded that these cell lines are probably derived from lymphocytic precursors. Cell lines with isoenzyme 4 may be the result of a facultative hybridisation between lymphocytes and monocytes. Profiles of acid phosphatases in virus-negative cell lines (Ramos, BJAB) were not significantly altered by conversion with EBV.

Acid Phosphatase↗
PubMed1977

[Isoenzymes of acid phosphatase in blood cells of normal subjects and patients with leukemia (author's transl)].

The activities of acid phosphatases (AP) were measured in leukocytes from patients with chronic myelocytic leukemia (CML), macrophages, granulocytes, in the fractionated mononuclear cells of patients with CML and with hairy-cell-leukemia (HCL) and in the cells from patients with acute leukemia (AL). The lowest activities were found in lymphocytes of normal subjects and of patients with chronic lymphatic leukemia (CLL) and in thrombocytes. Isoenzyme (IsE) 1 was characteristic for thymocytes, IsE 2 for granulocytes, IsE 3 for pathologic blast-cells, lymphocytes and thrombocytes, IsE 4 for macrophages, IsE 5 with components a and b for the mononuclear fraction of patients with HCL. In addition IsE 5 was detected in lymphocytes, macrophages and CLL-cells. In 4 patients with HCL the relative percentage of IsE-5-fraction was slightly greater than the percentage of tartrate resistant cells. In two patients with questionable HCL well marked IsE-5-fractions were recognized but no tartrate resistant cells. In one patient with HCL a relatively high percentage of tartrate resistant hairy-cells and in comparison an inadaquate low IsE-5-fraction was found. These different relations were explained with the more sensitive method of gelelectrophoresis and different affinity of substrates to AP.

Acid Phosphatase↗
PubMed1977

Raman spectroscopic investigation of the interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes.

The interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes is investigated by Laser-Raman spectroscopy. As revealed by the methylene C-H stretching mode the phase transition of the hydrocarbon chains near 40 degree C is eliminated in the presence of gramicidin A. Liposomes prepared from a mixture of lecithin and cholesterol seem to be unaffected by gramicidin A and show only the normal broadened phase transition.

Binding Sites↗