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Biomedical subjects

R Weber

Publications and source records attributed to R Weber.

At least 379 records · Page 21Linked to original sources
PubMed1983

Globin gene expression in Xenopus laevis: anemia induces precocious globin transition and appearance of adult erythroblasts during metamorphosis.

The expression of Xenopus laevis larval and adult globin genes after phenylhydrazine-induced anemia has been investigated at the cellular and molecular levels by means of cloned cDNA probes specific for the four main larval and the four main adult globin mRNA species. In the circulating blood of anemic metamorphic larvae there are at least two distinct populations of erythroblasts containing either larval or adult globin mRNA sequences. The cells expressing adult sequences replace those expressing larval ones at the end of metamorphosis. Under the influence of anemia the qualitative pattern of transcribed RNA species is not changed, but the larval to adult transition takes place earlier during development. This would imply that this transition is not strongly correlated with the morphological changes of metamorphosis. The abundance of the different larval globin mRNA species is similar and, as compared to control animals, not affected by the phenylhydrazine treatment. In anemic adults no reactivation of larval gene expression has been observed. The different adult globin mRNA species are present in comparable abundance, but the phenylhydrazine treatment appears to enhance expression of the alpha A II and beta A II genes, as compared to nonanemic individuals.

Anemia↗
PubMed1983

The Xenopus laevis globin gene family: chromosomal arrangement and gene structure.

Clones containing nine different larval and adult globin genes have been isolated from two genomic libraries of Xenopus laevis. They encompass three distinct DNA regions: a 70 kb region containing five genes in the order 5'-alpha Lla-alpha Llb-alpha Al-beta Al-beta Lla-3', all with the same transcriptional polarity; a 40 kb region with three genes, 5'-alpha Llla-alpha Lllb-alpha All-3', again with the same polarity; and a 10 kb segment comprising the beta Llla gene only. The beta All gene has not been found in our libraries. Genetic analysis has revealed two more beta L genes (beta Lllb, beta Lllb). Globin-like sequences have also been isolated, but have not been further characterized. The X. laevis globin gene family thus consists of 12 genes arranged in two clusters, each containing larval and adult alpha and beta genes in a unique, "symmetrical" arrangement. Electron microscopic analysis has revealed that Xenopus globin genes also comprise three exons and two introns, but differ from the globin genes of higher vertebrates in that the introns are much larger.

Animals↗
PubMed1983

An atypical Aspergillus flavus from a case of bronchopulmonary aspergilloma. A contribution to the cultural and serological diagnosis of A. flavus infections.

A slow-growing, non-pigmented hyphomycete was isolated from sputum and a fungus ball removed at autopsy from the lung. The patient, an alcoholic, also suffered from cirrhosis and primary carcinoma of the liver. The atypical and otherwise non-recognizable isolate showed a growth typical of Aspergillus flavus when cultured on sterilized peanuts. This observation indicates the diagnostic significance of such strains which have become atypical, as etiologic agents and sources of antigen. Serologically, the antigen of the atypical strain proved to be stronger than that of a typical A. flavus strain. In view of the simultaneous presence of the liver carcinoma and the absence of aflatoxin production by the atypical strain, the possible role of chronic colonization of the lung by A. flavus is discussed.

Aflatoxins↗
PubMed1982

Estrogen dramatically decreases albumin mRNA levels and albumin synthesis in Xenopus laevis liver.

The levels of albumin mRNA in Xenopus laevis liver were measured at various times after injection of estradiol using two different methods involving hybridization of cloned albumin cDNA to total liver RNA. The absolute levels of albumin mRNA fell by more than 95% during the first 4 days following estrogen treatment, then slowly returned to normal levels over the following 12 days. Albumin synthesis paralleled the albumin mRNA levels during the first 8 days after injection; but, 16 and 32 days after injection, albumin synthesis again decreased while albumin mRNA remained at normal levels. The time courses of the effects of estrogen on albumin and vitellogenin mRNA levels were different. Whereas albumin mRNA levels were minimal 4 days after estradiol injection, vitellogenin mRNA levels were maximal 8 days after injection.

Albumins↗
PubMed1982

Isolation and characterisation of the Xenopus laevis albumin genes: loss of 74K albumin gene sequences by library amplification.

The blood of the frog X.laevis contains 2 albumins of 68,000 and 74,000 daltons which are encoded in the liver by two related mRNAs. When an amplified X.laevis DNA library was screened with cloned albumin cDNA only 68,000 dalton albumin gene sequences were isolated. Hybridisation of the albumin cDNA to Southern-blots of Eco R1 digested X.laevis DNA showed that the sequences present in the recombinants did not account for all the fragments which hybridised on the Southern-blots. This indicated that 74K albumin gene sequences exist but that they are not present in the amplified DNA library. A X.laevis genomic library was therefore constructed and screened for albumin genes without amplification. Both 68K and 74K albumin gene sequences were isolated. Recombinants containing 74K albumin gene sequences grew extremely poorly and this probably explains why the 74K albumin sequences were ot isolated from the amplified library. Characterisation of the cloned DNA indicates that there is one sequence coding for the 68K albumin but two different sequences coding for the 75K albumin.

Animals↗
PubMed1982

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--treatment with lithium.

Two patients with SIADH after brain trauma are described. Features of SIADH are "inappropriate" antidiuresis and excessive natriuresis with negative sodium balance resulting in hyponatremia and plasma hypoosmolality which may lead to cerebral dysfunction. Oral lithium carbonate was beneficial in both patients. With plasma levels of lithium around 1 mmol/l a temporary impairment of renal concentrating ability and antinatriuresis with normalization of plasma sodium and plasma osmolality was observed. The SIADH subsided about 4 months after the original trauma, long after gross neurological symptoms had resolved.

Accidents, Traffic↗
PubMed1982

Divergence of the two albumins of X. laevis. Evidence for the glycosylation of the major 74K albumin.

The mRNAs coding for the 68,000 and 74,000 dalton serum albumins of Xenopus laevis were purified by hybridisation to their corresponding cloned cDNA and translated using the reticulocyte lysate. The primary translational product of the 68,000 dalton albumin has a molecular weight of 70,000 daltons suggesting that it is synthesised with a signal peptide which is cleaved during secretion. In contrast, the primary translational product of the 74,000 dalton albumin has a molecular weight of 72,000 daltons suggesting that it must be posttranslationally modified to account for the increased molecular weight of the mature protein. X. laevis oocytes injected with albumin mRNA secrete proteins of the same molecular weights as the mature albumins. When these translational products were chromatographed on concanavalin A Sepharose, the 74,000 dalton albumin was bound suggesting that it is glycosylated. Comparison of X. laevis and X. tropicalis albumins suggests that the 68,000 dalton albumin is similar to the primitive Xenopus albumin and that since the genome duplication which occurred in X. laevis, differences have arisen in both the length and processing of the primary translational product to account for the current difference in the molecular weights of the two X. laevis albumins.

Animals↗
PubMed1982

Psychiatric records: variations based on discipline and patient characteristics, with implications for quality of care.

In this study of the delivery of outpatient psychiatric care to Medicaid patients at all 29 free-standing psychiatric clinics and at six hospital clinics in New York City, the authors found that nonphysician mental health workers provided much direct patient care: diagnosis and identifying data, necessary for reimbursement, were always included in records whereas mental status and medical history were poorly documented; and nonphysicians in hospitals generally surpassed physicians in the latter two areas. An additional observation was that attitudes of mental health workers toward certain diagnostic and ethnic groups may be inferred from the selective completeness of their psychiatric record keeping.

Attitude of Health Personnel↗