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Biomedical subjects

S J Kemp

Publications and source records attributed to S J Kemp.

At least 37 records · Page 2Linked to original sources
PubMed1996

Involvement of protein tyrosine kinases in regulation of endothelial cell organization by basement membrane proteins.

During capillary formation, endothelial cell migration and organization are critically dependent on surrounding basement membrane proteins. These proteins serve as a physical support and are likely to provide signals which regulate migration and organization of the cells. In this study the possible involvement of tyrosine kinase signalling pathways in basement membrane-induced organization of human endothelial cells is examined. Interaction of endothelial cells with reconstituted basement membrane Matrigel activates tyrosine phosphorylation of several proteins including focal adhesion kinase. Inhibition of this pathway with tyrosine kinase inhibitors impairs localization of paxillin to focal adhesions and organization of actin filaments, decreases motility and elongation of endothelial cells, and prevents their organization into cords or tubes on basement membrane. These data demonstrate that basement membrane-induced modulation of endothelial cell motility, shape, and organization is critically dependent on tyrosine kinase signalling pathway(s) involving cytoskeletal proteins.

Basement Membrane↗
PubMed1996

Polymorphism at the bovine tumor necrosis factor alpha locus and assignment to BTA 23.

We have identified four single-strand conformation variants of the bovine tumor necrosis factor alpha gene by analysis of PCR-amplified fragments. The variants are inherited in Mendelian fashion and are informative for linkage mapping. We have mapped the bovine gene to Chromosome (Chr) 23 in a panel of somatic cell hybrids and observed genetic linkage to the major histocompatibility complex (BoLA) genes and microsatellite markers on bovine Chr 23 in an international bovine reference family panel. The distribution of the alleles was determined in cattle of different breeds and of different geographical origins, which included trypano-susceptible and trypano-tolerant cattle.

Animals↗
PubMed1996

Genetic control of resistance to trypanosomiasis.

To map the genetic sources of trypanotolerance in mice, a linkage analysis of survival following trypanosome challenge was performed by selective genotyping in a large F2 population produced by crossing the resistant C57BL/6 and susceptible BALB/c inbred mouse lines. We report evidence of a chromosomal region of large effect, possibly comprising more than one resistance locus, on Chromosome 17; and of further loci on Chromosomes 1 and 5. Together, these genes can account for all of the difference between the mean parental phenotypes.

Animals↗
PubMed1995

Parasite strain specificity of bovine cytotoxic T cell responses to Theileria parva is determined primarily by immunodominance.

The parasite strain specificity of CTL responses to Theileria parva varies among cattle immunized with the same parasite stock. We have investigated the influence of class I MHC on the strain specificity of CTL responses to T. parva in 19 cattle of defined class I phenotype immunized with either of two T. parva populations, in which protection to subsequent reciprocal challenge correlated with CTL strain specificity. In the majority of animals the response was restricted by the products of one MHC haplotype and there was a consistent bias to some haplotypes in preference to others. In 10 of 13 cattle expressing the molecularly defined MHC specificities A10 and KN104 on one haplotype, the CTL response was restricted entirely by this haplotype, thus allowing a precise analysis of the MHC restriction specificities. The MHC restriction specificity and the parasite population used for immunization both influenced the strain specificity of the response. By examining responses in identical twins immunized with different parasites or in animals before and after challenge with heterologous parasites, animals that mounted a strain-specific response to primary infection were shown to be capable of responding to Ags shared by the two parasite populations. These findings indicate that the strain specificity of CTL responses to T. parva is not determined primarily by immune response genes that define the inherent capacity to respond, but rather is a consequence of the response in individual animals being biased toward a limited number of immunodominant peptide-MHC determinants.

Animals↗
PubMed1995

Sesamoid arthrodesis for hyperextension of the thumb metacarpophalangeal joint.

Forty-two sesamoid arthrodeses performed since 1986 were reviewed. Thirty-seven cases were considered successful. Hypertension recurred in 3 of the 20 procedures performed for cerebral palsy and 1 of the 21 performed in association with basal joint arthroplasty for arthritic conditions. The single post trauma case was successful. Flexion was preserved. Prevention of hyperextension of the metacarpophalangeal joint assists in reducing metacarpal adduction in cerebral palsy and has a stabilizing effect in basal joint arthroplasty.

Adolescent↗
PubMed1995

A panel of polymorphic bovine, ovine and caprine microsatellite markers.

A panel of 81 new polymorphic bovine microsatellite markers is described, together with further information on a previously reported group of 16 markers. The mean polymorphism information content of the 97 markers determined in 20 cattle was 0.66. Seventy-three of these markers have been assigned to chromosomes by either linkage analysis or use of hybrid cell panels. Thirty-nine of the markers were polymorphic in sheep, and 32 were polymorphic in goat. This study identified a set of 18 robust markers that were polymorphic in all three species and that covered 14 bovine chromosomes. This provides a single group of markers, which would be suited to genetic distance analysis and parentage control in cattle, sheep and goat.

Animals↗
PubMed1995

A polymorphism in randomly amplified DNA that differentiates the Y chromosomes of Bos indicus and Bos taurus.

A small number of west African Bos taurus cattle breeds, including the N'Dama, constitute a valuable genetic resource by virtue of their ability to remain productive under trypanosomiasis challenge. However, introgression of Bos indicus genes into the trypanotolerant breeds, particularly by introduction of zebu bulls, is a threat to this resource. This work describes the characterization and cloning of a bovine randomly amplified polymorphic DNA (RAPD) that is generated in polymorphic DNA (RAPD) that is generated in polymerase chain reaction (PCR) with the 10 base primer ILO1065 from Bos indicus male templates, but not from B. taurus male templates or female templates of either type. Male-specific sequences with homology to the RAPD also occur in B. taurus breeds. This suggests that the polymorphism may be due to base substitution(s) in an ILO1065 priming site, or insertion/deletion events either affecting priming sites or occurring between sites on the cattle Y chromosome. We have shown that cattle, whether of B. indicus or B. taurus phenotype, which possess a typically B. indicus metaphase Y chromosome on the basis of QFQ banding, have a B. indicus ILO1065-generated genotype. The ILO1065-primed RAPD can be used in a simple dot blot assay as a probe of RAPD-PCR products, to provide a convenient, reliable and effective means of detecting introgression of zebu genes in B. taurus cattle populations.

Africa, Western↗
PubMed1994

Fifteen new synteny assignments of microsatellites to the bovine genome.

A panel of 36 hamster-bovine hybrid cell lines was used to assign 15 bovine microsatellites. Locus identification, synteny group and/or chromosome assignment and registration number were as follows: ILSTS001 (U22, Chr07, D7S13), ILSTS002 (U09, Chr18, D18S7), ILSTS004 (U10, Chr01, D1S28), ILSTS005 (U05, Chr10, D10S25), ILSTS006 (U22, Chr07, D7S8), ILSTS008 (U24, Chr14, D14S15), ILSTS010 (U27, DU27S11), ILSTS011 (U24, Chr14, D14S16), ILSTS012 (U16, Chr11, D11S26), ILSTS015 (U07, Chr25, D25S3), ILSTS016 (U04, Chr21, D21S22), ILSTS017 (X, DXS11), ILSTS018 (U15, Chr06, D6S15), ILSTS019 (U07, Chr25, D25S7) and ILSTS020 (U05, Chr10, D10S27). These results contribute to the international effort to improve the bovine genetic map.

Animals↗
PubMed1994

PCR-RFLP typing of the bovine myoglobin gene.

We have identified substitutions in the 3' untranslated region of the bovine myoglobin gene, one of which affects an MboII restriction enzyme site resulting in a bi-allelic restriction fragment length polymorphism. Co-dominant inheritance of the alleles in three reference families was observed using a polymerase chain reaction--restriction fragment length polymorphism assay. The distribution of the alleles seems characteristic of cattle type--one of the alleles was not detected in purely taurine breeds. Furthermore, we mapped, using the polymerase chain reaction on a bovine-rodent somatic cell hybrid panel, the myoglobin gene to bovine chromosome five. It is therefore syntenic with gamma-interferon and insulin-like growth factor in which we have not found polymorphism. The myoglobin locus therefore serves as a type one marker on bovine chromosome five.

Alleles↗
PubMed1994

Randomly primed PCR amplification of pooled DNA reveals polymorphism in a ruminant repetitive DNA sequence which differentiates Bos indicus and B. taurus.

By amplification of pools of DNA representative of different bovine populations with single short oligonucleotide primers of random sequence, we were able rapidly to identify markers which distinguish the two major subspecies of domestic cattle, Bos taurus and B. indicus. One of the marker polymorphisms was found to be in a novel, dispersed DNA sequence which occurs in several ruminant species. The marker will assist in the detection of crossbreeding between Zebu and B. taurus types where this threatens a potentially valuable trypanosomiasis-resistant B. taurus genetic resource in West Africa. In addition, the marker will be useful for exploration of the evolutionary relationships of the major subspecies of domestic cattle. The general approach used to identify population-specific DNA polymorphisms has potentially broad application in definition of species, breeds and populations and will be of generic value in studies of genome evolution.

Animals↗
PubMed1994

Characterization of Zebu cattle breeds in Tanzania using random amplified polymorphic DNA markers.

A total of 141 short primers, of arbitrary nucleotide sequence, were used singly in polymerase chain reactions to amplify DNA fingerprints in pools of DNA representing three Zebu cattle breeds. Two primers, which discriminated between the breed-specific DNA pools were used further to amplify individual pool components in order to establish band frequencies of the amplified fingerprints. One of the primers (ILO 1127) amplified a RAPD fingerprint in 61% of TSZ animals but less than 6% in the other breeds, while another primer (ILO 1065) revealed a DNA sequence common to 89% of the Boran animals and less than 30% in the other two breeds. Bandsharing and mean average percentage difference calculated within and between the three breeds using RAPD fingerprint data showed a higher degree of homogeneity within than across the breeds and indicated measurable divergence between the three breeds. It is concluded that RAPD polymorphisms are useful as genetic markers for cattle breed differentiation.

Animals↗
PubMed1993

A polymorphism in the bovine gamma-S-crystallin gene revealed by allele-specific amplification.

A polymorphism was detected in the 3' untranslated region of the bovine gamma-S-crystallin gene by direct sequencing of polymerase chain reaction (PCR) products from genomic DNA of an N'Dama bull and a Boran cow. A set of three PCR primers was designed to detect this difference and thus give allele-specific amplification. The two allele-specific primers differ in length by 20 nucleotides so that the allelic products may be distinguished by simple agarose gel electrophoresis following a single PCR reaction. This provides a simple and rapid assay for this polymorphism.

Alleles↗
PubMed1993

Polymerase chain reaction analysis of mitochondrial DNA polymorphism in N'Dama and Zebu cattle.

A study of polymorphisms of mitochondrial DNA (mtDNA) of West African N'Dama (Bos taurus) and East African Zebu (B. indicus) cattle was carried out to obtain information on maternal phylogenetic relationships between these breeds. A relatively large sample size was made possible by using polymerase chain reaction (PCR) amplification of DNA prepared from small blood samples to generate fragments of two known polymorphic mtDNA regions, one within the gene encoding subunit 5 of NADH dehydrogenase and one encompassing the entire D-loop. This approach allowed us to achieve a higher resolution restriction analysis on mtDNA from more animals than would have been possible by conventional methods. PCR-amplified mtDNA of 58 animals from five populations was examined at 26 restriction sites by 16 enzymes. In this way 154 nucleotides of mtDNA were scanned for polymorphism. Six polymorphic sites were located by this means, five of which were within the D-loop and one of which was within the NADH dehydrogenase 5 gene. None of the polymorphisms observed could be considered typical of breed or type.

Africa, Western↗
PubMed1993

A panel of bovine, ovine and caprine polymorphic microsatellites.

We report a set of six new bovine microsatellite polymorphisms based on (CA)n repeats. They are highly polymorphic and thus represent valuable markers for genome mapping. Four of the six are polymorphic in sheep and two are polymorphic in goats. One, which is polymorphic in cattle and sheep and apparently monomorphic in goats, is X-chromosome specific and has potential value in, for example, sex determination and detection of chimaerism.

Alleles↗