PubMed Health⌕ Search

Biomedical subjects

J Martin

Publications and source records attributed to J Martin.

At least 559 records · Page 31Linked to original sources
PubMed1993

Twenty-four novel hemophilia B mutations revealed by rapid scanning of the whole factor IX gene in a French population sample.

Full scanning of the factor IX gene by means of denaturing gradient gel electrophoresis enabled us to determine the molecular defects in 48 out of 49 hemophiliacs and to evaluate the spectrum of factor IX mutations in the French population. Our results further document the high molecular heterogeneity of the disease and the efficiency of this rapid screening method for disease-causing mutations. This direct approach, which is based on computer-aided analysis of the whole coding, promoter and exon-flanking factor IX gene sequences, proved to be helpful for carrier detection and prenatal diagnosis in most hemophilia B families, including sporadic cases. Moreover, we were able to identify 24 novel molecular defects of various natures in the factor IX gene.

Base Sequence↗
PubMed1993

The impact of relaxation/imagery on high level noise exposure: a pilot study.

In this study the detrimental impact of high level noise on temporary threshold shift (TTS) (i.e., hearing loss), was reduced when subjects were given suggestions of imaginary ear muffs attenuating the amplitude and aversive aspects of the noise. This effect was small, however, and only apparent when subjects' responses to noise under a relaxation/imagery (self-regulation) condition was compared to exposure while working on crossword puzzles. The subject's level of hypnotic susceptibility was not related to the outcome. Implications of these findings were discussed.

Adult↗
PubMed1993

HLA polymorphism in the Havasupai: evidence for balancing selection.

The characterization and analysis of genetic variation at the HLA loci provides important insight for population geneticists trying to understand the evolutionary forces that have shaped human populations. This study describes the HLA-A and HLA-B loci serotyping and statistical analysis on an isolated Native American population, the Havasupai of Arizona. Four alleles at the HLA-A locus were identified, while eight alleles were found at the HLA-B locus. These variants were present as 20 of 32 potential two-locus haplotypes, with five of the six most common haplotypes exhibiting high positive linkage disequilibrium. Significant homozygote deficiency (heterozygosity excess) was detected both at HLA-A and at HLA-B. This deviation from Hardy-Weinberg proportions was not attributable to nonselective causes such as different allele frequencies in males and females or avoidance of consanguineous matings. In addition, the distribution of alleles at both HLA-A and HLA-B was more even than expected from neutrality theory; that is, the observed Hardy-Weinberg homozygosity was only 62.4% of that expected under neutrality. These observations suggest that balancing selection is of major importance in maintaining genetic variation at HLA-A and HLA-B.

Female↗
PubMed1993

Expression of MHC class II A alpha k transgene. Pairing with endogenous beta-chain is dependent upon affinity and competition.

Studies on cell lines transfected with MHC class II genes have revealed important limitations on the assembly of haplotype-mismatched A alpha/A beta complexes. We have investigated pairing restriction in vivo by analyzing transgenic mice that carry an A alpha k gene on several H-2 haplotypes. Previously, we reported the A alpha k transgenic expression on the cell surface of H-2b and H-2u strains. Further transcomplementation studies performed with high A alpha k-expressing transgenic lines revealed that A alpha k chain can pair with A beta b,s,f,d,v, or u chains but not with A beta q. Homozygosity for the A alpha k transgene increased the expression of mixed heterodimers. The inefficient assembly of haplotype-mismatched class II polypeptides results from their inability to compete with the matched pairs. The higher affinity between the matched pairs can be overcome by increased synthesis of the mismatched pair. Thus, there is no "strict" sequence-based restrictions on pairing.

Animals↗
PubMed1993

Complement C3 gene expression and regulation in human glomerular epithelial cells.

Extra-hepatic synthesis of complement is thought to mediate local tissue inflammatory injury. To investigate this phenomenon in the glomerular epithelial cell (GEC), we examined the biosynthesis and regulation of gene expression of the third component of complement in isolated human GEC derived from normal tissue. Metabolic labelling and immunoprecipitation studies demonstrated that C3 protein was synthesized, processed and secreted by GEC under basal conditions. The secreted C3 alpha and beta polypeptide chains had identical electrophoretic mobilities with those of hepatic C3. Examination of cellular RNA using semi-quantitative polymerase chain reaction (PCR) showed that C3 gene expression was present in unstimulated GEC and was increased by stimulation with interferon-gamma (IFN-gamma) in a time- and dose-dependent manner. Tumour necrosis factor-alpha (TNF-alpha), while mediating an increase in monocyte U937 C3 expression, revealed no evidence of regulation of GEC C3 gene expression. These results indicate that human GEC spontaneously express the C3 gene and that increased gene expression is regulated by IFN-gamma. These observations may reflect part of a wider mechanism of protection against or mediation of local, immune-mediated tissue injury.

Cells, Cultured↗
PubMed1993

Acceptability of behavioral treatments: influence of knowledge of behavioral principles.

The relation of staff knowledge of behavioral principles to ratings of treatment acceptability for interventions used in the management of self-injurious behavior (SIB) was examined with 57 direct-care staff members from an ICF/MR. Case descriptions of an adult with severe mental retardation who exhibited SIB were presented, followed by descriptions of six behavioral interventions rated on acceptability. Subjects also completed a 25-item measure of general knowledge of behavioral principles. Results indicated that staff age and educational attainment but not treatment acceptability ratings were significantly related to knowledge scores. Implications of the findings were discussed.

Adult↗
PubMed1993

A drama of growth and recognition. Drama in therapy with abused children.

1. Psychodrama is a form of psychotherapy which uses drama as its main medium. 2. It has four main stages: warm-up, action, sharing and re-integration. Each stage has therapeutic elements in its own right. 3. Psychodrama is adaptable to a variety of settings and situations. 4. It has various forms, such as sociodrama and monodrama, and is separate from drama therapy, which centres on metaphor and its relationship with drama, although the two can often be used in partnership.

Child↗
PubMed1993

Microbial carriage, sepsis, infection and acute GVHD in the first 25 BMT at the Royal Liverpool Children's Hospital.

The first 25 BMTs at the Royal Liverpool Children's Hospital (Alder Hey) were performed between April 1987 and July 1991. The aim of this report is to evaluate selective decontamination of the digestive tract (SDD) during the first post-BMT month in this series of 14 allografts and 11 autografts. SDD is a method used to abolish carriage of potentially pathogenic microorganisms including yeasts, Staphylococcus aureus and Gram-negative bacilli (GNB). Chlorhexidine mouth wash was used to decontaminate the oropharynx, and neomycin, colistin (polymyxin E) and nystatin (NEOCON) were given to eradicate gut carriage. Oropharyngeal decontamination was successful in 48% of patients, gut carriage was abolished in 60%, and eradication of the carrier state at both sites was achieved in 33%. A septic response was seen in 76% of children and 36% developed septicaemia (indigenous Gram-positive cocci only). A low carriage index for the target microorganisms during the study manoeuvre of SDD was associated with negative blood cultures (p < 0.01). Acute GVHD occurred in 28% of allografts, but was seen in none of the successfully decontaminated children (p < 0.05). It is concluded that septicaemia from yeasts and GNB, but not the septic response, were successfully prevented by SDD.

Adolescent↗
PubMed1993

Transfer of hybrid plasmids based on the replicon pRRI7 from Escherichia coli to Bacteroides and Prevotella strains.

New shuttle vectors based on a Prevotella ruminicola 9.5 kb cryptic plasmid (pRRI7) inserted within the Escherichia coli vector pKC71, carrying the Ccr/Emr Bacteroides marker, were constructed. These constructs (pKBR23-1 and pKBR23-2) were transferred into Bacteriodes distasonis, Bacteroides thetaiotaomicron, Bacteroides uniformis and into P. ruminicola NCFB 2202 either by conjugal mobilization or by electroporation. Another pRRI7 derivative based on pKC72, pKBR23-3, was smaller (13.1 kb) and non-mobilizable. By electroporation, it was transferred to Bact. distasonis and P. ruminicola. Being derived from pRRI7 which is compatible with the shuttle plasmid pRRI207, the host/vector combination involving P. ruminicola NCFB 2202 and pKBR23-3 offers new possibilities for genetic investigations in rumen anaerobic bacteria after further introduction of a second readily selectable marker within pRRI207 or pKBR23-3.

Bacteroides↗
PubMed1992

Two related genes encoding extremely hydrophobic proteins suppress a lethal mutation in the yeast mitochondrial processing enhancing protein.

The processing enhancing protein of mitochondria (PEP) is an essential component that has been shown to participate in proteolytic removal of NH2-terminal signal peptides from precursor proteins imported into the mitochondrial matrix. Using a yeast strain bearing a PEP mutation that renders it temperature-sensitive, an approach of genetic suppression was taken in order to identify additional components that could be involved with protein import: high copy plasmids comprising a yeast genomic library were tested for ability to suppress the 37 degrees C growth defect. Two plasmids were isolated, pSMF1 and pSMF2, which suppressed the growth defect nearly as well as the cloned PEP gene itself. Sequence analysis of the rescuing genes predicted extremely hydrophobic proteins with sizes of 63 and 60 kDa, respectively. Remarkably, the predicted SMF1 and SMF2 products are 49% identical to each other overall. To test the requirement for SMF1 and SMF2, the chromosomal genes were disrupted. Individual disruption was without effect, but cells in which both genes were disrupted grew poorly. When mitochondria were prepared from the double disruption strain grown in a nonfermentable carbon source, they were morphologically normal but defective for translocation of radiolabeled precursor proteins. SMF1 protein was provisionally localized to the mitochondrial membranes using epitope tagging. We suggest that SMF1 and SMF2 are mitochondrial membrane proteins that influence PEP-dependent protein import, possibly at the step of protein translocation.

Amino Acid Sequence↗
PubMed1992

Prevention of protein denaturation under heat stress by the chaperonin Hsp60.

The increased synthesis of heat shock proteins is a ubiquitous physiological response of cells to environmental stress. How these proteins function in protecting cellular structures is not yet understood. The mitochondrial heat shock protein 60 (Hsp60) has now been shown to form complexes with a variety of polypeptides in organelles exposed to heat stress. The Hsp60 was required to prevent the thermal inactivation in vivo of native dihydrofolate reductase (DHFR) imported into mitochondria. In vitro, Hsp60 bound to DHFR in the course of thermal denaturation, preventing its aggregation, and mediated its adenosine triphosphate-dependent refolding at increased temperatures. These results suggest a general mechanism by which heat shock proteins of the Hsp60 family stabilize preexisting proteins under stress conditions.

Adenosine Triphosphate↗