PubMed Health⌕ Search

Biomedical subjects

K Gibson

Publications and source records attributed to K Gibson.

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

Frequency of the IVS12 + 5G-->A splice mutation of the fumarylacetoacetate hydrolase gene in carriers of hereditary tyrosinaemia in the French Canadian population of Saguenay-Lac-St-Jean.

Hereditary tyrosinaemia type I (HTI), an autosomal recessive inborn error of metabolism, is caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The highest incidence of HTI is observed in the Saguenay-Lac-St-Jean region (SLSJ) (Québec, Canada), where 1 out of 22 individuals is thought to be a carrier. A splice mutation (IVS12 + 5G-->A) has recently been identified in this particular region. Here, we have determined the frequency of this mutation in a population of obligate carriers from the SLSJ region by allele-specific oligonucleotide hybridization and a method using a restriction enzyme digestion. Over 95 per cent of the HTI carriers were found to have the IVS12 + 5G-->A splice mutation. Screening for this mutation based on the two methods reported here is thus a reliable and rapid way of detecting carriers of hereditary tyrosinaemia type I in that region at high risk.

Amino Acid Metabolism, Inborn Errors↗
PubMed1996

Influence of the HLA-DRB1 locus on susceptibility and severity in rheumatoid arthritis.

We examined HLA-DR genotype risk in 288 patients with rheumatoid arthritis who were carefully categorized for disease severity. Five hundred ethnically-matched bone-marrow donors were controls. A hierarchy of positive allelic associations was noted with DRB1*0401 (p < 10(-38), *0404,8 (p < 10(-43), *0405 (p < 10(-8), *10 (p < 10(-3) and *0101,2 (p < 10(-2), while DRB1*0403 was negatively associated (p = 0.02). The DRB1 genotype relative risks (and 95% CIs) for RA were: *0404,5,8/*0404,5,8 = 36.2 (15-87), *0401/*0404,5,8 = 31.3 (18-55), *401/*0401 = 18.8 (11-35), *0101,2/*0404,5,8 = 6.0 (2-14), *0101,2/*0401 = 6.4 (3-12), *0101,2/*0101,2 = 1.3 (0.3-6), *10/*0404,5,8 = 27.8 (5-148), *10/*0401 = 20.8 (5-89), *10/*0101,2 = 22.3 (5-96), *0404,5,8/DRX = 5.0 (3-8), *0401/DRX = 4.7 (3-7), *0101,2/DRX = 2.3 (1.4-4), *10/DRX = 3.4 (0.8-14). No significant correlation of DRB1 genotypes was found with severity of RA as judged by nodules or articular erosions.

Arthritis, Rheumatoid↗
PubMed1996

Effect of HLA type and hypocomplementaemia on the expression of parvovirus arthritis: one year follow up of an outbreak.

OBJECTIVES: To determine the effect of HLA type and hypocomplementaemia on the duration and severity of joint involvement in parvovirus infection (HPV). METHODS: Forty seven patients were selected on a geographical basis from 83 with proven HPV infection during an outbreak that occurred in Oxfordshire in 1993. They were contacted by questionnaire a year later. Thirty five patients were available for examination and blood sampling. Subjects were typed for HLA-DRB1 alleles and HLA-B27 status. Immunological profiles, including C3 and C4 complement components, were determined. RESULTS: Joint symptoms occurred in all patients. They resolved within a week in 12 patients and persisted beyond one year in 19. On review, none had a picture of rheumatoid arthritis, but three patients had developed carpal tunnel syndrome. Decreased C4 was found in four. The HLA frequencies were similar to those in controls; however, joint symptoms persisted for more than one week in all HLA-DR4 positive patients (p = 0.009). There was no relation between the severity of joint symptoms and either HLA type, or hypocomplementaemia. CONCLUSIONS: Joint symptoms are common in parvovirus infection and the presence of HLA-DR4 may be associated with persistence of joint symptoms beyond one week. This study revealed no evidence of progression to rheumatoid arthritis.

Adult↗
PubMed1996

Constitutive activation of a phosphoinositidase C-linked G protein in murine fibroblasts decreases agonist-stimulated Ca2+ mobilization.

We compared Ca2+ signaling and inositol polyphosphate metabolism in NIH-3T3 cells stably transfected with cDNA encoding either the wild-type G protein G16 alpha subunit or a GTPase-deficient alpha 16 subunit (Q212L-alpha 16). Constitutive activation of phosphoinositidase C (PIC) in cells expressing Q212L-alpha 16 was demonstrated by 1) an increased basal level of [3H]inositol polyphosphates, 2) an enhanced rate of [3H]inositol polyphosphate accumulation in cells treated with 10 mM LiCl, and 3) an increased rate of incorporation of [3H]inositol into cell lipids. Q212L-alpha 16 cells had a diminished cell growth rate. Basal intracellular Ca2+ concentration was equivalent in Fura-2 acetoxymethyl ester-loaded Q212L-alpha 16 cells compared with controls; however, calcium release in Q212L-alpha 16 cells exposed to ionomycin, ATP (a G protein-linked agonist), or platelet-derived growth factor (a tyrosine kinase-linked agonist) was decreased. Permeabilized, 45Ca-loaded Q212L-alpha 16 cells released less 45Ca at each concentration of inositol-1,4,5-trisphosphate than did control cells. Accordingly, the total amount of inositol trisphosphate (IP3) receptor protein was decreased in Q212L-alpha 16 cells relative to controls. These data demonstrate that Q212L-alpha 16 cells maintain physiological levels of cytoplasmic calcium and partially loaded Ca2+ stores in the face of constitutively active PIC. This is accomplished, at least in part, by down-regulation of IP3 receptor number. Thus, diminution in cell growth rate in Q212L-alpha 16 cells seems to be attributable to a combination of at least two effects: a direct effect of PIC activation leading to partial depletion of Ca2+ stores and an indirect, adaptive response resulting in a decreased IP3 receptor number.

3T3 Cells↗
PubMed1996

Interethnic differences in the association of tumor necrosis factor promoter polymorphisms with systemic lupus erythematosus.

OBJECTIVE: To assess the role of polymorphisms in the promoter region of the tumor necrosis factor-alpha (TNF-alpha) gene in susceptibility to systemic lupus erythematosus (SLE). METHODS: Two ethnically different populations of patients with SLE (49 white from the UK and 49 black from South Africa) were genotyped for TNF-238 and TNF-308 polymorphisms using amplification refractory mutation system-polymerase chain reaction (PCR). HLA-DR genotypes were assigned to the patients and controls either serologically or by PCR and sequence specific oligonucleotides. The frequencies of the respective variants were compared between patients and ethnically matched controls. RESULTS: No significant differences were found in the frequency of the TNF-238 variants in either ethnic group. At TNF-308, the TNF2 variant was significantly increased (p = 0.04) in white patients with SLE compared to controls. However, TNF2 was strongly associated with HLA-DR3 (p = 0.00002), which also showed a strong trend of increase in the white patients (p = 0.06). In contrast, in the black patients with SLE in whom DR2 but not DR3 was increased, the frequency of TNF2 was actually reduced rather than increased. CONCLUSIONS: The increase of TNF2 in Caucasians with SLE is most likely due to linkage disequilibrium between TNF2 and DR3. Furthermore, the observation that TNF2 seems to be reduced in blacks with SLE strongly suggests this polymorphism is not an independent risk factor for SLE. Overall, our data indicate that the TNF-238 and TNF-308 promoter polymorphisms do not confer susceptibility to SLE.

Base Sequence↗
PubMed1995

A prospective, randomized trial of a six-week ambulatory medicine rotation.

BACKGROUND: Medical schools are placing increased emphasis on training students in the ambulatory setting, but few studies show the benefit or academic risk of such innovation. The authors studied the effect of such a new rotation with a rigorous study design. METHOD: From a group of 166 third-year students at the Uniformed Services University of the Health Sciences F. Edward Hébert School of Medicine assigned in 1990-91 to do six weeks of their third-year medicine clerkship at Walter Reed Army Medical Center, 106 volunteers were randomized to six weeks either on the usual rotation on the general medicine wards (69 students) or to a new ambulatory rotation (37 students). Multiple pre- and postclerkship parameters were used to evaluate clerkship skills and knowledge; eventual internship choice was determined. RESULTS: The randomization was successful. Postclerkship performances were the same in (1) the medicine subject examination of the National Board of Medical Examiners, (2) a multiple-choice test in interpreting laboratory results, (3) blinded rating by an expert panel of the quality of final written histories and physical exams, (4) blinded rating by an expert panel of the students' written case analyses of their own patients, and (5) a written multiple-step examination of problem-solving ability. Any differences between groups favored the ambulatory group. An increase in choice of primary care internships among students randomized to the ambulatory rotation was not significant. CONCLUSION: It is possible to study innovative rotations using a prospective, randomized design. Substituting a six-week block ambulatory experience for a ward rotation did not decrease students' abilities to write up or analyze complex cases.

Ambulatory Care↗
PubMed1995

Monitoring performance in a community mental health centre.

Reports on a three-month period of evaluation of changes in the perceived life stress, coping and strain of 60 consecutive new attenders at a community mental health centre, which served to monitor performance. Emphasizes the need to incorporate good measurement into a systematic approach to quality assurance.

Adaptation, Psychological↗
PubMed1995

Immunogenetic analysis of HLA-DR10 homozygous individuals.

Molecular, cellular and serological analysis of Major Histocompatibility Complex alleles was performed on three individuals who appeared to be HLA-DR10 homozygous by DNA restriction fragment analysis. Each donor was of different ethnic origin: Caucasoid, Asian Indian and African Negroid. The results of our studies show that the Caucasoid and Asian donors are indeed homozygous for the HLA-DR10 allele, while the African donor also possesses the DRB1*0103 allele. Homozygosity for the HLA-A1-B37-Cw6-DR10-DQ5 haplotype in the Caucasoid donor was confirmed by familial segregation analysis. The B-lymphoblastoid cell line produced from this donor should prove useful in studies of HLA immunogenetics.

Alleles↗
PubMed1995

HLA class II antigens associated with systemic lupus erythematosus in black South Africans.

OBJECTIVE: To assess the associations of HLA class II antigens with systemic lupus erythematosus (SLE) in black South Africans. METHODS: HLA-DRB1 genotype frequencies assigned by polymerase chain reaction (PCR) amplification and sequence specific oligonucleotide probes were compared between 49 black SLE patients from Baragwanath Hospital and 87 ethnically matched controls. HLA-DQA1 and -DQB1 genotypes were also assigned in 45 of the SLE patients and 74 controls by PCR using sequence specific primers. RESULTS: HLA-DRB1*02 was increased in the patients compared with controls (odds ratio = 3.67; 95% confidence interval = 1.49 to 9.02; p < 0.005). HLA-DQB1*0201 was not associated with development of the disease itself, but was associated with the presence of Ro antibodies (p = 0.01). HLA-DRB1*03 was less strongly linked to DQB1*02 in this population than in white populations and was not associated with SLE. CONCLUSIONS: In black South Africans there is evidence for a locus on DR2 haplotypes contributing to SLE. Another gene, possibly HLA-DQB1*02, not linked to DR2 is involved in the subset of patients exhibiting Ro antibodies.

Adolescent↗
PubMed1994

Analysis of the MHC class II encoded components of the HLA class I antigen processing pathway in ankylosing spondylitis.

OBJECTIVES: The evaluation of the role of polymorphism within the class II encoded antigen processing genes, LMP2 and TAP, in susceptibility to ankylosing spondylitis (AS). METHODS: Eighty five patients with ankylosing spondylitis, 35 B27 positive healthy controls, and 55 unrelated healthy controls were studied. TAP1 and TAP2 alleles were assigned by ARMS PCR, and LMP2 alleles were assigned by restriction enzyme digestion of a PCR product. RESULTS: The TAP1C allele was increased in the AS group (6%) compared with random controls (1%), p = 0.03 and TAP2E was increased in AS (3.5%) compared with random controls (0%), p = 0.05. However, the frequencies of these alleles were also increased in B27 matched controls. There were no differences in LMP2 allele or genotype frequencies between AS and either of the control groups. Partitioning of patients according to presence or absence of uveitis did not reveal any significant associations. CONCLUSIONS: Increases of the minor TAP alleles, 1C and 2E, in AS reflect linkage disequilibrium between these alleles and HLA-B27. Polymorphism of the class I antigen processing pathway does not contribute significantly to AS susceptibility nor to the development of anterior uveitis associated with AS.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Alveolar macrophage kinetics after inhalation of 239PuO2 by CBA/Ca mice: changes in synthesis of DNA.

For workers in the nuclear industry, the primary route for the entry of radioactive materials into the body is by inhalation, and the rate of clearance of particles from the pulmonary region of the lung is an important factor in determining radiation dose. It is the function of alveolar macrophages (AM) to maintain the sterility of the lung and to remove insoluble particles from the respiratory surfaces and airways. The AM population is not static, and under normal conditions the loss of macrophages from the alveoli via the conducting airways is balanced by renewal. Studies of the effects of external irradiation on the kinetics of AM are numerous, but to date little is known about the effects of inhaled radioactive particles. In this investigation the effects of inhaled 239PuO2 (plutonium dioxide) particles on the synthesis of DNA by AM were studied at times up to 77 days after exposure. We also measured the number of cells recovered by bronchoalveolar lavage and the incidence of AM with nuclear aberrations. The latter provides a sensitive indicator of the effects of radiation. One of the earliest effects observed after exposure to 239PuO2 is a reduction in the number of AM recovered by lavage. This reduction is associated with a 3-fold reduction in the proportion of AM undergoing DNA synthesis at early times after exposure. The overall mean pulse labeling index of AM recovered from sham-exposed mice is 1.68%, and no trend is observed with time.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1990

Sphingosine stimulates cellular proliferation via a protein kinase C-independent pathway.

Sphingosine, a metabolite of membrane sphingolipids, is generally considered to be cytotoxic for a variety of cell types. However, we have found that sphingosine at low concentrations stimulates DNA synthesis and acts synergistically with known growth factors to induce proliferation of quiescent Swiss 3T3 fibroblasts. Structurally related analogs of sphingosine, such as N-stearoylsphingosine and other long chain aliphatic amines, had no mitogenic effects, suggesting that sphingosine did not induce nonspecific membrane perturbations. Sphingosine, which has been proposed to be a physiological inhibitor of protein kinase C, also markedly potentiates the mitogenic effect of the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Sphingosine still stimulates DNA synthesis in cells made protein kinase C deficient by prolonged treatment with phorbol ester. At mitogenic concentrations, sphingosine does not bind to protein kinase C as shown by its lack of effect on phorbol dibutyrate binding. Only at higher concentrations, in the cytotoxic range, was there a displacement of phorbol dibutyrate from its cellular-binding sites. In contrast to sphingosine, H-7, a known inhibitor of protein kinase C, inhibited the mitogenic response to TPA and the TPA-induced phosphorylation of the 80 kDa cellular substrate of protein kinase C. Our results suggest that sphingosine may play an important role as a positive regulator of cell growth acting in a fundamentally different, protein kinase C-independent pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Children in political violence.

There is an urgent need to conduct research into the effects of political conflict on children growing up in South Africa. This paper discusses some international literature which may be relevant to researchers in this area. The first section briefly assesses the usefulness of the background literature on children in war and disaster situations. The second section outlines some of the clinical effects of political conflict on children. The third illustrates some of the ways in which intra-personal, inter-personal and contextual factors play a role in the stress process. The fourth section incorporates previous discussion into a model for understanding the effects of political conflict on children and offers a brief critique of some of the existing research. The final section explores the implications of the international literature for the South African researcher and examines the usefulness of conducting this kind of research.

Child↗
PubMed1989

Psychiatry training and research.

There is a growing concern that residents in psychiatric training programs may not be receiving an adequate exposure to the principles of research. This paper examines the need for such exposure and outlines a framework wherein the fundamentals of clinical research could be demonstrated to the resident physician.

Canada↗