Search PubMed⌕ Search

Biomedical subjects

S Povey

Publications and source records attributed to S Povey.

At least 37 records · Page 2Linked to original sources

MEETING REPORT

Explore the source record for details and available documents.

Journal Article↗

Familial distal renal tubular acidosis is associated with mutations in the red cell anion exchanger (Band 3, AE1) gene.

All affected patients in four families with autosomal dominant familial renal tubular acidosis (dRTA) were heterozygous for mutations in their red cell HCO3-/Cl- exchanger, band 3 (AE1, SLC4A1) genes, and these mutations were not found in any of the nine normal family members studied. The mutation Arg589--> His was present in two families, while Arg589--> Cys and Ser613--> Phe changes were found in the other families. Linkage studies confirmed the co-segregation of the disease with a genetic marker close to AE1. The affected individuals with the Arg589 mutations had reduced red cell sulfate transport and altered glycosylation of the red cell band 3 N-glycan chain. The red cells of individuals with the Ser613--> Phe mutation had markedly increased red cell sulfate transport but almost normal red cell iodide transport. The erythroid and kidney isoforms of the mutant band 3 proteins were expressed in Xenopus oocytes and all showed significant chloride transport activity. We conclude that dominantly inherited dRTA is associated with mutations in band 3; but both the disease and its autosomal dominant inheritance are not related simply to the anion transport activity of the mutant proteins.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

Dynamic molecular combing: stretching the whole human genome for high-resolution studies.

DNA in amounts representative of hundreds of eukaryotic genomes was extended on silanized surfaces by dynamic molecular combing. The precise measurement of hybridized DNA probes was achieved directly without requiring normalization. This approach was validated with the high-resolution mapping of cosmid contigs on a yeast artificial chromosome (YAC) within yeast genomic DNA. It was extended to human genomic DNA for precise measurements ranging from 7 to 150 kilobases, of gaps within a contig, and of microdeletions in the tuberous sclerosis 2 gene on patients' DNA. The simplicity, reproducibility, and precision of this approach makes it a powerful tool for a variety of genomic studies.

Calpain↗

Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the widespread development of distinctive tumors termed hamartomas. TSC-determining loci have been mapped to chromosomes 9q34 (TSC1) and 16p13 (TSC2). The TSC1 gene was identified from a 900-kilobase region containing at least 30 genes. The 8.6-kilobase TSC1 transcript is widely expressed and encodes a protein of 130 kilodaltons (hamartin) that has homology to a putative yeast protein of unknown function. Thirty-two distinct mutations were identified in TSC1, 30 of which were truncating, and a single mutation (2105delAAAG) was seen in six apparently unrelated patients. In one of these six, a somatic mutation in the wild-type allele was found in a TSC-associated renal carcinoma, which suggests that hamartin acts as a tumor suppressor.

Amino Acid Sequence↗

A 1.7-megabase sequence-ready cosmid contig covering the TSC1 candidate region in 9q34.

The disease gene TSC1 has been genetically mapped to human chromosome region 9q34, in a 4-cM interval between the markers D9S149 and D9S114. Within this interval there is conflicting genetic evidence as to the finer localization of the gene. We have used finger-printing methods and hybridization to produce a 1.7-Mb overlapping clone map covering the TSC1 candidate region, with a single gap of 20 kb. We have localized 12 previously cloned genes and 17 genetic markers on this map and have confirmed the order of the genetic map. This deep set of overlapping clones is now ready to be used for candidate gene isolation, for transcription studies, or for sequencing.

Chromosome Mapping↗

Report on the Fifth International Workshop on Chromosome 9 held at Eynsham, Oxfordshire, UK, September 4-6, 1996.

The Fifth International workshop on chromosome 9 comprised a gathering of 36 scientists from seven countries and included a fairly even distribution of interests along chromosome 9 as well as a strong input from more global activities and from comparative mapping. At least eight groups had participated in the goal set at the previous workshop which was to improve the fine genetic mapping in different regions of chromosome 9 by meiotic breakpoint mapping in allocated regions and this has resulted in some greatly improved order information. Excellent computing facilities were available and all contributed maps were entered not only into SIGMA (and thence submitted to GDB) but also into a dedicated version of ACEDB which can be accessed on the Web in the form of one of 28 slices into which the chromosome has been arbitrarily divided. It was generally agreed that the amount of data is now overwhelming and that the integration and validation of all data is not only unrealistic in a short meeting but probably impossible until the whole chromosome has been sequenced and fully annotated. Sequence-ready contigs presented at the meeting totalled about 3 MB which is about one fiftieth of the estimated length. The single biggest barrier to integration of maps is the problem of non-standard nomenclature of loci. In the past 2 workshops efforts have been made to compare traditional 'consensus' maps made by human insight (still probably best for small specific regions) with those generated with some computer assistance (such as SIGMA) and those generated objectively by defined computer algorithms such as ldb. Since no single form of map or representation is entirely satisfactory for all purposes the maps reproduced in the published version of the report are confined to one of the genetic maps, in which Genethon and older markers have been incorporated, a Sigma map of the genes as symbols together with a listing of known 'disease' genes on chromosome 9, and a revised assessment of the mouse map together with a list of mouse loci predicted to be on human chromosome 9. One of the 28 ACEDB slices is also shown to illustrate strengths and weaknesses of this approach. Workshop files include not only all maps available at the time but also details of loci and details of the meiotic breakpoints in the CEPH families (http:/(/)www.gene.ucl.ac.uk/scw9db.shtml) .

Animals↗

A new alpha 1-antitrypsin mutation, Thr-Met 85, (PI Zbristol) associated with novel electrophoretic properties.

A new AAT allele (PI Zbristol) has been discovered in a woman with an obstetric history of three perinatal deaths from fulminant liver disease and no living offspring. She and her father were both PI M1Zbristol heterozygotes. The Zbristol protein is active as a proteinase inhibitor but appeared to be deficient in the plasma to about the same degree as the S protein in MS heterozygotes. It focuses on the basic side of Z and lacks the normal pattern of secondary isoforms associated with the commonly occurring AAT variants and migrates faster than normal on an SDS electrophoresis gel. The Zbristol mutation was found to be a C to T transition at codon 85 changing ACG (Thr) to ATG (Met). This disrupts the N-glycosylation site starting at Asn 83 preventing glycosylation at residue 83 in the PI Zbristol protein and explains the protein isoelectric focusing and SDS gel electrophoresis results. An analysis of haplotypes in the propositus and her father indicated that the Zbristol mutation occurred on the common M1(Val 213) genetic background. The new mutation also led to the generation of an NlaIII restriction endonuclease recognition site. Cell lines from two offspring tested for the presence of this NlaIII site revealed that one had the variant and the other did not. Thus, the relationship between Zbristol and fulminant liver disease in the offspring is unclear.

Amino Acid Substitution↗

Mapping ESTs to the TSC1 candidate interval by use of the 'Science 96' transcript map.

The transcription map of the human genome published by Schuler et al. (1996) is a valuable resource in which approximately one quarter of all human genes have been mapped with respect to genetic framework markers using radiation hybrids. We have taken information from this map to provide potential genes within the TSC1 candidate region on chromosome 9q34. In so doing we have been able to provide an independent assay of the quality of the radiation hybrid mapping by using somatic cell hybrids and a 2 Mb cosmid contig covering the TSC1 region as mapping tools. In addition, we have built sequence contigs of ESTs for 25 clusters. This has shown that about 20% of the relevant EST clusters in the Unigene resource (Boguski & Schuler 1995) contain chimaeric clones.

Animals↗

Development of a microsatellite-based approach to co-segregation analysis of familial hypercholesterolaemic kindreds.

Co-segregation studies based on a selection of intragenic restriction fragment length polymorphisms of the low density lipoprotein receptor (LDLR) gene have been used extensively both for research and diagnostic studies of familial hypercholesterolaemia (FH) families, because direct mutation screening remains complex. Here we describe the development and application of a more efficient approach to co-segregation studies based on highly informative dinucleotide and tetranucleotide repeats flanking the LDLR gene. A series of microsatellites (D19S391, D19S394, D19S221 and D19S179) were selected for study on the basis of linkage analysis in the CEPH families using intragenic polymorphisms for a TA repeat (exon 18) in the LDLR gene, and earlier data for a Pvu II polymorphism (intron 15). A physical map of the region of chromosome 19 also contributed to this selection. One marker in particular, D19S394, sited 150 kilobases telomeric to the gene, was extremely useful, displaying 90% heterozygosity, robust PCR of tetranucleotide repeats without stutter bands, and no recombination with the LDLR gene (theta = 0, LOD 68). Use of this marker in the families of twenty-three FH probands from Hampshire demonstrated co-segregation of the hyperlipidaemia phenotype with the LDLR gene region, except in one family with defective apolipoprotein B-100, and a family turning out to display familial combined hyperlipidaemia. This approach should facilitate the search for any families where FH does not co-segregate with the LDLR gene, and will enhance the repertoire of molecular diagnostic tools available for FH.

Adolescent↗

Pre-AIDS deaths in HIV infection related to intravenous drug use.

We prospectively collected data on deaths in the Edinburgh City Hospital HIV cohort of patients (60-70% acquired via injection drug use) from October 1986 to September 1994. Sixty-four patients (25% of all HIV deaths or 2.5/100 person-years) had died without an AIDS diagnosis, and 42 (66%) of these had autopsy data available. Some pre-AIDS deaths (20% or 0.5/100 person-years) were the expected consequence of underlying medical conditions diagnosed during life: the remainder (80% or 1.98/100 person-years) were sudden or unexpected. Examining the underlying conditions, drug overdoses accounted for 45% or 1.1/100 person-years; bacterial sepsis, 25% or 0.6/100 person-years; liver disease, 26% or 0.6/100 person-years; and an undiagnosed AIDS condition, 9% or 0.2/100 person-years. Drug overdoses were the commonest cause of pre-AIDS death in this cohort of patients predominantly infected via IDU, but many of the sudden deaths had significant underlying pathology, which may have increased their susceptibility to an overdose of drugs. In future, death before an AIDS diagnosis should be classified into Medical or Expected Non-AIDS (MNA or ENA) and Sudden Non-AIDS (SNA).

Bacterial Infections↗

Localization of human flavin-containing monooxygenase genes FMO2 and FMO5 to chromosome 1q.

The human flavin-containing monooxygenase (FMO) gene family comprises at least five distinct members (FMO1 to FMO5) that code for enzymes responsible for the oxidation of a wide variety of soft nucleophilic substrates, including drugs and environmental pollutants. Three of these genes (FMO1, FMO3, and FMO4) have previously been localized to human chromosome 1q, raising the possibility that the entire gene family is clustered in this chromosomal region. Analysis by polymerase chain reaction of DNA isolated from a panel of human-rodent somatic cell hybrids demonstrates that the two remaining identified members of the FMO gene family, FMO2 and FMO5, also are located on chromosome 1q.

Animals↗

Macrophage presentation of endogenous self-protein: the MHC class II presentation pathway is not accessible to intracellular C5 or alpha 1-antitrypsin.

This paper addresses the question of whether macrophages can present biosynthesized protein in a class II-restricted manner using the endogenous rather than the exogenous pathway of presentation. Two distinct self-antigens, the fifth component of complement (C5) and alpha 1-antitrypsin, were studied. Both antigens are serum proteins synthesized by hepatocytes and macrophages. To direct synthesis exclusively to macrophages chimeras were constructed by transfer of bone marrow from donors expressing the self-antigen into irradiated hosts deficient for the respective self-antigen. Macrophages from such mice were unable to present biosynthesized C5 to class II-restricted T cells, even when preactivated in vivo. While C5 production by macrophages is low and may not reach critical levels of intracellular protein required to access the class II presentation pathway, human alpha 1-antitrypsin, expressed as a transgene in mice, was synthesized at 600-fold higher levels than C5. Nevertheless, macrophage-synthesized alpha 1-antitrypsin in bone marrow chimeras was not presented in the context of class II--even in a mutant form which is sequestered in high amounts in the endoplasmic reticulum. We conclude that macrophages are unable to use the endogenous class II presentation pathway for these two model self-antigens. As a consequence MHC class II-restricted T cells specific for C5 and alpha 1-antitrypsin remain ignorant of the presence of self-antigen within macrophages and are neither tolerized nor rendered autoimmune.

Animals↗

EagI and NotI linking clones from human chromosomes 11 and Xp.

EagI and NotI linking libraries were prepared in the lambda vector, EMBL5, from the mouse-human somatic cell hybrid 1W1LA4.9, which contains human chromosomes 11 and Xp as the only human component. Individual clones containing human DNA were isolated by their ability to hybridise with total human DNA and digested with SalI and EcoRI to identify the human insert size and single-copy fragments. The mean (+/- SD) insert sizes of the EagI and NotI clones were 18.3 +/- 3.2 kb and 16.6 +/- 3.6 kb, respectively. Regional localisation of 66 clones (52 EagI, 14 NotI) was achieved using a panel of 20 somatic cell hybrids that contained different overlapping deletions of chromosomes 11 or Xp. Thirty-nine clones (36 EagI, 3 NotI) were localised to chromosome 11; 17 of these were clustered in 11q13 and another nine were clustered in 11q14-q23.1. Twenty-seven clones (16 EagI, 11 NotI) were localised to Xp and 10 of these were clustered in Xp11. The 66 clones were assessed for seven different microsatellite repetitive sequences; restriction fragment length polymorphisms for five clones from 11q13 were also identified. These EagI and NotI clones, which supplement those previously mapped to chromosome 11 and Xp, should facilitate the generation of more detailed maps and the identification of genes that are associated with CpG-rich islands.

Animals↗

Mapping of human non-muscle type cofilin (CFL1) to chromosome 11q13 and muscle-type cofilin (CFL2) to chromosome 14.

Cofilin is a widely-distributed, intracellular, actin binding protein which is involved in the translocation of actin-cofilin complex from cytoplasm to nucleus. We have cloned a non-muscle-type cofilin (CFL1) from a human promyelocytic cDNA library and mapped this to human chromosome 11 by PCR amplification of 3' untranslated sequence in a panel of rodent-human somatic cell hybrids, and to the interval 11q12-q13.2 in a chromosome 11 somatic cell hybrid mapping panel. Confirmation of regional localisation to 11q13 has been obtained by fluorescent in situ hybridisation of genomic cosmid clones, by demonstration of the presence of both SEA (the human homologue of avian retrovirus proviral tyrosine kinase, 11q13) and CFL1 in some of these clones and by close linkage of CFL1 to SEA in a panel of high-dose irradiation hybrids. We have identified human muscle-type cofilin sequences by comparison of human expressed sequence tags with M-type cofilins of other species and we have mapped the human M-type cofilin, CFL2, to chromosome 14.

Actin Depolymerizing Factors↗

Chromosomal localisation of genes coding for human and mouse liver cytosolic cysteine dioxygenase.

A panel of 22 hybrids was tested for the presence of the gene coding for human cysteine dioxygenase (CDO) by using human specific oligonucleotide primers in the polymerase chain reaction. Detection of human CDO completely correlated with the presence of human chromosome 5. A human total genome cosmid library was screened with a PCR product from the coding region of human CDO cDNA and the two positive clones identified were used in fluorescent in situ hybridisation (FISH) analysis on metaphase chromosome spreads. Fluorescent signals were seen on chromosome 5q22-23. Interspecific backcross mapping in the mouse indicated that Cdo, the mouse homologue of CDO, is situated in the central region of mouse chromosome 18 which shares a region of homology with human chromosome 5.

Animals↗