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Biomedical subjects

A Brown

Publications and source records attributed to A Brown.

At least 289 records · Page 16Linked to original sources
PubMed1994

The genomic structure of an insertional mutation in the dystonia musculorum locus.

We have previously identified a line of transgenic mice, Tg4, in which an hsp68-lacZ hybrid gene has inserted into the dystonia musculorum (dt) locus on chromosome 1. We have confirmed the localization of the Tg4 integration site to the proximal region of mouse chromosome 1 by interspecific backcross analysis. One end of the integration complex has been cloned and we have used single-copy probes from the flanking region to screen a mouse genomic library. Several overlapping lambda phage clones have been isolated and arranged into a contig spanning 75 kb of genomic DNA. Probes from the genomic contig have enabled us to characterize the wildtype and Tg4 loci. We report that the integration of the transgene was accompanied by a deletion of 45 kb of host genomic sequences with no other detectable rearrangement in the Tg4 genome.

Animals↗
PubMed1994

Human homolog of a mouse sequence from the dystonia musculorum locus is on chromosome 6p12.

Dystonia musculorum is a hereditary neurodegenerative disease in mice that affects sensory neurons. In an effort to clone the gene responsible for this disorder, we have assembled a genomic contig spanning 75 kb of the dystonia musculorum (dt) locus. Within this genomic contig, we have identified a small restriction fragment that shows evolutionary conservation to rat, hamster, rabbit, and human genomic DNA. Using this mouse sequence, we have cloned the conserved human genomic fragment. Sequence analysis of the mouse and human genomic fragments revealed that they share a sequence similarity of 82% over 175 bp. A panel of human/rodent somatic cell hybrids was used to map the human genomic sequence to Chromosome (Chr) 6, and high-resolution in situ hybridization (FISH) allowed it to be sublocalized to 6p12. The human homolog of the mouse Bpag1 gene, a gene tightly linked to the mouse dt gene, also maps to Chr 6. Thus, this comparative mapping reveals a new region of conserved synteny between the chromosomes of mouse and human. Mapping the human homolog of the mouse dt gene enables us to initiate linkage studies to identify neurodegenerative disorders that may be caused by mutations in this gene.

Animals↗
PubMed1994

A PCR strategy for the isolation of glutathione S-transferases (GSTs) from nematodes.

Anchor based PCR technology has been used to isolate a GST sequence from the gastro-intestinal nematode Heligmosomoides polygyrus. A 800 base pair product was amplified from first-strand cDNA using primers based on the N-terminal sequence of purified H. polygyrus GST (upstream primer) and a non-specific polyadenylate tail with an anchor sequence (downstream primer). The product was cloned into pUC18 and sequenced. A reading frame of 648 bases in the sequence encoded a protein which has 30% homology with the alpha family of mammalian glutathione S-transferases.

Amino Acid Sequence↗
PubMed1994

Glutathione S-transferases from the gastrointestinal nematode Heligmosomoides polygyrus and mammalian liver compared.

Glutathione S-transferases have been partially characterised from the gastrointestinal nematode Heligmosomoides polygyrus. Two major subunit families were purified (24 and 23 kDa) with N-terminal homology to the mammalian Alpha family. Four dimeric forms of GST were purified from the nematode by glutathione-affinity chromatography, two major enzymes (pI 8.1, 5.0) and two minor forms (pI 5.8, 5.3). The purified GST pool could neutralize model and lipid peroxides via peroxidase activity but not peroxidation derived reactive carbonyls via glutathione transferase activity. Antisera raised to the pooled nematode GSTs appeared to recognize other Strongylida GSTs more strongly on Western blotting compared to mammalian GSTs.

Amino Acid Sequence↗
PubMed1994

Neurasthenic fatigue, chemical sensitivity and GABAa receptor toxins.

Following observation of fatigue syndromes in people who have been occupationally exposed to pesticides and insecticides which exert their toxicity through the GABAa receptor, we have formulated the hypothesis that fatigue syndromes in general may be secondary to altered sensitivity of the GABAa receptor. We discuss the possible involvement of organochlorine compounds which are widespread in the environment. Organophosphate compounds may have similar toxic effects through damaged cholinergic input to the dentate gyrus of the hippocampus where cholinergic and GABAergic transmission are closely linked.

Adult↗
PubMed1994

Mutations at the PAX6 locus are found in heterogeneous anterior segment malformations including Peters' anomaly.

Mutation or deletion of the PAX6 gene underlies many cases of aniridia. Three lines of evidence now converge to implicate PAX6 more widely in anterior segment malformations including Peters' anomaly. First, a child with Peters' anomaly is deleted for one copy of PAX6. Second, affected members of a family with dominantly inherited anterior segment malformations, including Peters' anomaly are heterozygous for an R26G mutation in the PAX6 paired box. Third, a proportion of Sey/+ Smalleye mice, heterozygous for a nonsense mutation in murine Pax-6, have an ocular phenotype resembling Peters' anomaly. We therefore propose that a variety of anterior segment anomalies may be associated with PAX6 mutations.

Amino Acid Sequence↗
PubMed1994

Renal artery embolism. Correlation with scintigraphic and radiographic findings.

The diagnosis of renal artery embolism should be considered in patients with cardiac disease who present with abdominal or flank pain in association with deteriorating renal function. Often the diagnosis is delayed or missed owing to the nonspecific, varied, and protean clinical manifestations. A case is presented of bilateral renal artery emboli, and initial and long-term scintigraphic and radiographic correlations are provided. Renal scintigraphy should be the initial study of choice. In addition, this procedure allows for sequential noninvasive evaluation of renal function.

Aged↗
PubMed1994

Linkage analysis between schizophrenia and a microsatellite polymorphism for the D5 dopamine receptor gene.

Using 23 multiplex pedigrees we tested for linkage between schizophrenia and a microsatellite polymorphism for the D5 dopamine receptor gene (DRD5). Assuming autosomal dominant inheritance and a maximum penetrance of 0.6, an overall lod score of -4.54 was derived at 0% recombination. For recessive transmission the summary lod score was -8.37 at 0% recombination. These data suggest that mutations of the D5 dopamine receptor gene are unlikely to be of major etiological importance in the pathogeneses of schizophrenia in the families studied. However, our study does not exclude the D5 dopamine receptor gene as a candidate gene for schizophrenia because some of our families were not informative for linkage and because of the likelihood of genetic heterogeneity.

Adolescent↗
PubMed1994

Herpesvirus saimiri small RNA and interleukin-4 mRNA AUUUA repeats compete for sequence-specific factors including a novel 70K protein.

A highly oncogenic strain of the lymphotropic tumour virus herpesvirus saimiri (HVS; strain 484-77) expresses four small RNAs (HSUR1 to 4) in high copy numbers in transformed T cells. In HSUR1 and HSUR2 the 5' terminal regions contain conserved AUUUA sequence repeats. The same AUUUA repeats occur in the 3' non-coding regions of growth factor, lymphokine and protooncogene mRNAs, and the sequence is involved in rapid mRNA degradation. We report here that by using a highly specific u.v. cross-linking method we identified a novel 70K binding factor with AUUUA sequence specificity. Non-radiolabelled competition and V8 protease analysis show that the protein can form a complex with the 3' non-coding region of interleukin-4 mRNA and bind the AUUUA repeats of a HVS small RNA. We also detected an AUUUA-specific minor 32K human protein with the same electrophoretic mobility as a marmoset factor implicated in growth factor mRNA destabilization. The findings are consistent with the hypothesis that the viral small RNAs can compete for factors involved in rapid degradation of growth factor mRNAs and may contribute to viral oncogenesis.

Base Sequence↗
PubMed1994

Obstacles and approaches to clinical database research: experience at the University of California, San Francisco.

With increasing availability of clinical data in machine-readable form, and decreasing cost of storing and manipulating that data, retrospective research using clinical databases has become more feasible. Nonetheless, much of the potential for clinical research using these data remains unrealized. Obstacles to clinical database research include difficulty accessing data, difficulty using retrospective data to draw valid inferences about medical tests and treatments, and a shortage of investigators trained and interested in using a clinical database to answer their questions. At the University of California, San Francisco, we have developed a Clinical Database Research Program (CDRP) to try to overcome these obstacles. The CDRP maintains a relational database of patient data obtained from diverse sources and a small staff dedicated to providing such data to researchers. The CDRP staff also provides support for design and analysis of studies using the database--the development of methods for such studies is our primary research interest. Finally, to increase the number of investigators using the database for research, we are integrating training in clinical epidemiology and clinical research methods into residency and fellowship training, and offering an elective in clinical database research for trainees who wish to undertake a specific project.

Databases, Factual↗
PubMed1994

Preliminary impacts of PACS technology on radiology department operations.

The potential benefits of digital imaging to clinical operations focuses on both quantitative and qualitative improvements. In the future it is postulated that it will totally replace analog imaging, creating the 'filmless' Radiology department. Although this could result in dramatic savings in film costs, realization of this scenario will require continued improvements in the performance and cost of component technologies, acceptance by the medical and legal communities of the reliability of the medium, and changes in the practice and process of radiology. Baltimore VAMC has recently become one of the truly 'filmless' radiology departments through use of a leading commercial Picture Archiving and Communications System (PACS) and DHCP's Digital Imaging System. This document outlines the results of a preliminary assessment of PACS technology as it is installed at Baltimore, and its impact on operations.

Analog-Digital Conversion↗