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Biomedical subjects

J D Mathews

Publications and source records attributed to J D Mathews.

At least 19 recordsLinked to original sources
PubMed1992

Hepatitis B virus markers in children and staff in Northern Territory schools.

OBJECTIVE: To measure the prevalence of hepatitis B virus (HBV) infection in children and staff at Northern Territory schools. DESIGN: Children in Years 5-7 in 24 selected primary schools were invited, with parental consent, to provide demographic and ethnic details, and a capillary blood sample for tests for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs). School staff participated on a similar basis. PARTICIPANTS: 1104 children, comprising 556 from ethnic groups (originating from the United Kingdom, Ireland and northern Europe) previously reported as "low HBV prevalence", 439 Aboriginal Australians, and 109 from "other" ethnic groups (originating from Asia, the Pacific, the Middle East and southern Europe); and 209 school staff, comprising 180 from "low HBV prevalence" ethnic groups, and 29 from Aboriginal and other ethnic groups. RESULTS: Prior HBV infection (i.e. serum positive for HBsAg or anti-HBs) was detected in 28.7% of children (46.9% of 439 Aborigines; 13.7% of the 556 children from the "low prevalence" groups and 32.1% of the 109 from the "other" groups). HBsAg was detected in 8.2% of Aboriginal children, in 0.36% of those from "low prevalence" groups, and in 1.8% of those from the "other" groups. Aboriginal children in rural schools had the highest prevalence of HBV: 5.4% were positive for both HBsAg and anti-HBs, and an additional 9.8% were positive for HBsAg alone. In urban schools, the prevalence was highest in the "other" ethnic groups. For school staff, the prevalence of HBV infection was 12.8% for those from "low prevalence" ethnic groups, and 37.9% for those from all remaining groups (including Aborigines). CONCLUSION: In the Northern Territory the prevalence of past HBV infection is high in children and school staff from ethnic groups previously known to be at higher risk of HBV infection. For students and staff from ethnic backgrounds expected to be at low risk, HBV prevalence is greater than in individuals from similar backgrounds in other parts of Australia. HBV vaccination is now offered to all infants in the Northern Territory. These results also provide a rationale for the more widespread use of HBV vaccine in other situations where significant HBV transmission might occur.

Child↗
PubMed1992

Hospitalisation patterns in children from 10 aboriginal communities in the Northern Territory.

OBJECTIVE: To describe childhood hospitalisation patterns in rural Aboriginal communities in the Northern Territory. DESIGN: Longitudinal data for 1976-1985 were collected retrospectively between March 1986 and December 1987. COHORT: All children born between 1 January 1976 and 31 December 1985 and identified in records at 10 community health centres were included in the study, except for 30 children who were residents of more than one community. Records of hospital admissions were ascertained for the remaining 2254 children until five years of age or 31 December 1985, whichever was earlier. RESULTS: Mean admission rates for Aboriginal children aged 0-1 year were two to three times the national average, and there was a fourfold excess in the number of days in hospital and the number of deaths before the age of five years for Aboriginal infants. Admission rates varied by community, age, year and sex: at 0-6 months of age, rates for communities ranged from a minimum of 0.21 to a maximum of 1.46 admissions per child-year at risk and mean rates increased from 0.50 per year in 1976 to 1.05 in 1985; mean admission rates declined from 0.84 per child-year at age 0-6 months to 0.12 at age 37-60 months. Boys were admitted to hospital more frequently than girls. For communities, hospital stay ranged from a minimum of 2.7 to a maximum of 15.3 hospital days per child-year at risk. CONCLUSIONS: Differences of up to sevenfold in hospitalisation rates between communities highlight the potential for primary and secondary prevention of childhood disease in Aboriginal communities.

Anemia↗
PubMed1992

Social and environmental factors in 10 aboriginal communities in the Northern Territory: relationship to hospital admissions of children.

OBJECTIVE: To identify social and environmental differences associated with differences in admission rates of children from 10 rural Aboriginal communities in the Northern Territory. DESIGN: Between March 1986 and December 1987, records of hospital admissions of the cohort of children for 1976-1985 were examined retrospectively; cross-sectional measurements of 74 historical, social and environmental characteristics of each community were collected. SAMPLE: All 1961 children born between 1 January 1976 and 31 December 1985 and still living in the 10 communities. METHOD: Scores on social and environmental factors for each community were generated by factor analysis. Generalised linear interactive modelling was used to investigate the association between these scores and admission rates. RESULTS: Mean admissions per child-year at risk were higher in Central Australian communities (range, 0.41-0.93) than Top End communities (0.26-0.38). Factor I accounted for 30% of the social and environmental differences between communities: communities with a high score on this factor had more houses, fewer shared toilets, more electrical appliances, better personal hygiene and a history of mission administration. High scores on this factor were predictive of lower admission rates and the factor explained most of the differences in admission rates between the Top End and Central Australian communities. Factor VI, correlated with dilapidated dwellings and fewer Aboriginal Health Workers, explained some differences in admission rates between six Top End communities. CONCLUSIONS: Social and environmental factors correlated with the degree of community development are associated with the health of Aboriginal children. Improved development programs should be community-controlled and evaluated to identify the social, educational, behavioural and environmental changes that are most effective in improving health.

Child, Preschool↗
PubMed1992

Streptococcal infection and renal disease markers in Australian aboriginal children.

OBJECTIVE: To demonstrate an association between markers of streptococcal infection and markers of glomerulonephritis in Aboriginal children. DESIGN: A cross-sectional study of Aboriginal children of school age. SETTING: Three Aboriginal communities in the Northern Territory--two, coastal and one, desert. PARTICIPANTS: Sixty children, randomly selected from the school roll, were studied in each community; thus there were 180 children in total, aged 5-17 years. Midstream urine and venous blood was collected and swabs were taken from the pharynx and from impetiginous skin lesions or axillary skin in the absence of impetigo. Clinical records were examined for evidence of past glomerulonephritis. MAIN OUTCOME MEASURES: Swabs were cultured for beta-haemolytic streptococci and isolates were grouped; serum was tested for titres of antistreptolysin O (ASO) and antideoxyribonuclease B (anti-DNaseB). Protein and creatinine levels were measured in urine, and a ratio of protein to creatinine (UPC) of more than 50 mg protein per mmol creatinine was taken as a measure of significant proteinuria. Urine was examined microscopically for glomerular haematuria (greater than 10 red blood cells per microL with at least 20% dysmorphic red cells). RESULTS: Group A beta-haemolytic streptococci were isolated from the throat swabs of two children and from skin swabs of 25 (13.9%) children; 20 of these were from impetiginous lesions and five from normal axillary skin. beta-Haemolytic streptococci of group C or G were grown from the throat swabs of 13 (8.1%) children. The median titre of ASO (256 IU) was raised compared with a reference level, and the median titre of anti-DNaseB (3172 IU) was particularly high; ASO titres were significantly higher in 31 children with impetigo than in 149 children without impetigo. Significant proteinuria was present in 7 (3.9%) children and glomerular haematuria in 16 (8.9%). Glomerular haematuria was present in 2/7 (28%) children with proteinuria, 4/21 (19%) children with a past history of post-streptococcal glomerulonephritis, in 5/31 (16%) of those with impetigo and in 4/25 (16%) of those with positive skin cultures. However, none of these prevalences was significantly greater than the prevalence of glomerular haematuria among the other children. The prevalence of proteinuria differed significantly between communities and increased significantly with age. Furthermore, the differences in childhood proteinuria observed between communities in this study were parallel with community differences in the prevalence of proteinuria in a related study of adults. CONCLUSIONS: Group A streptococci are important causes of impetigo in Aboriginal children. Streptococcal skin infection may contribute to glomerular haematuria, proteinuria and persistent glomerulonephritis in Aboriginal children, and possibly to chronic glomerulonephritis in adult life. Public health programs are needed to reduce the prevalence of impetigo and group A streptococcal infections in Aboriginal communities; longitudinal studies are needed to test the relationship between streptococcal skin infection in Aboriginal children and chronic renal disease in later life.

Adolescent↗
PubMed1991

Iatrogenic influences on the heritability of childhood tonsillectomy: cohort differences in twin concordance.

In 1980-82, a mailed questionnaire was completed by 3,810 pairs of adult twins enrolled on the Australian NH&MRC Twin Register. Twins were asked whether they had had their tonsils out and, if so, at what age. The sample was divided into four birth cohorts of approximately equal size, and only childhood tonsillectomy (to the age of 18) was considered. The prevalence of tonsillectomy differed markedly between cohorts, being highest in those born in the 1940s and early 1950s. Within each cohort, the prevalence was very similar in MZ and DZ twins, yet concordance was much higher in MZ twins, indicating the importance of genetic factors in predisposition to tonsillectomy. However, the proportions of variance in liability due to genetic and shared environmental factors differed markedly between cohorts. In the 1950s, when tonsillectomy was fashionable, shared environment accounted for 60% of variance and genetic factors for only 29%. However, by the early 1960s, when tonsillectomy was going out of fashion, heritability was up to 0.82 and shared environment accounted for only 10% of variance. Our results illustrate, once again, that heritability is not a constant, but depends on the precise characteristics of the population and the time at which it is studied.

Australia↗
PubMed1991

Preferential binding of Chlamydia trachomatis to subsets of human lymphocytes and induction of interleukin-6 and interferon-gamma.

The interactions between Chlamydia trachomatis and human blood mononuclear leukocytes were studied using flow cytometry, immunofluorescence, electron microscopy and cytokine assays. Under serum-free conditions, elementary bodies (EB) of C. trachomatis were found to bind to human T lymphocytes as well as to B cells and monocytes/macrophages (M phi). For all cell types the binding was saturable, rapid, temperature-independent and independent of the chlamydia-specific serological status of the donor. Similar proportions of T and B cells bound EB at similar levels. In the T cell population, proportionally less CD8+ cells bound EB. Whereas M phi phagocytosed and destroyed the bound micro-organisms for lymphocytes, the Chlamydia remained at the surface, adherent to morphologically featureless membrane areas and showed no evidence of uptake even after long periods at 37 degrees C. Host molecules modulated these basic binding patterns: a heat-stable serum factor inhibited EB binding to T cells and a heat-labile serum factor enhanced binding to B cells. Stimulation with C. trachomatis EB rapidly elicited cytokine production by lymphocytes including interleukin-6 from B cells and interferon-gamma (IFN-gamma) from T and/or nonT/nonB cells. The responses were irrespective of the serological status of the donor. The findings suggest that C. trachomatis-leucocyte interactions may differ from the interactions of other bacteria and human leucocytes. The possible relationship between leucocyte-binding, cytokine induction, and the pathognomonic development of lymphoid follicles during mucosal C. trachomatis infections is discussed.

Bacterial Adhesion↗
PubMed1990

Twin concordance for a binary trait: III. A bivariate analysis of hay fever and asthma.

Self-reported histories of hay fever and asthma were obtained from 3,808 pairs of adult twins 18 years and over registered with the Australian National Health Medical Research Council Twin Registry (1232 MZF, 567 MZM, 751 DZF, 352 DZM, 906 DZO). The prevalence of hay fever and asthma was 0.32 and 0.13, respectively, with little variation with zygosity, sex, and age. The associations between twin pairs for these two traits were analysed, under the assumption of constant prevalences, as a special case of a log-linear model for binary traits in pedigrees using the statistical package GLIM. The model assumption that there are no second- or higher-order interactions was tested in the 2 X 2 X 2 X 2 table of twin by disease outcomes without revealing strong evidence of departure, even in this large data set. The log-linear modelling showed that only three first-order interactions, namely 1) between hay fever in a twin pair, 2) asthma in a twin pair, and 3) hay fever and asthma in the same twin, were necessary to describe the data. The first two interaction terms were significantly larger in identical pairs; the third was independent of zygosity. Under this parsimonious model, there was a significant difference between identical and fraternal pairs in marginal correlation, both in asthma and hay fever, and in the cross-correlation between hay fever in one twin and asthma in the other. This suggests that genetic factors are implicated in both hay fever and asthma and that some of these genetic factors are common (at least among a subgroup of individuals) to both traits.

Adolescent↗
PubMed1990

Genetics of asthma and hay fever in Australian twins.

The occurrence of self-reported asthma/wheezing and hay fever among 3,808 pairs of twins from the Australian National Health and Medical Research Council Twin Registry was examined for evidence of genetic transmission by path analytic methods. The cumulative prevalence of asthma or wheezing was 13.2% and of hay fever, 32%. There were significant correlations in liability to reported disease among twins, and these were higher in monozygotic twins (MZ) (r = 0.65) than in dizygotic twins (DZ) (r = 0.25), and in male MZ twins (r = 0.75) compared with female MZ twins (r = 0.60). Analysis under the assumptions of the classic twin model suggested that there were genetic factors common to asthma and hay fever, with a correlation in genetic liability to the traits of 0.52 for men and 0.65 for women. These genes acted substantially in a nonadditive fashion in men but not in women. As the genetic correlation was significantly less than unity, this implied additional genetic factors influencing either or both diseases individually. The estimated heritability of these diseases was 60 to 70% in this population. Environmental causes of both diseases also were correlated (r = 0.53 for men and 0.33 for women). Cigarette smoking was only weakly associated with wheezing.

Adult↗
PubMed1988

Effects of the heavy usage of kava on physical health: summary of a pilot survey in an aboriginal community.

Health status was assessed in 39 kava users and 34 non-users in a coastal Aboriginal community in Arnhem Land. Twenty (27%) respondents were very heavy (mean consumption, 440 g/week) users of kava; 15 (21%) respondents were heavy (310 g/week) users of kava and four (5%) respondents were occasional (100 g/week) users of kava. Kava users were more likely to complain of poor health and a "puffy" face, and were more likely to have a typical scaly rash, and slightly-increased patellar reflexes. Very heavy users of kava were 20% underweight and their levels of gamma-glutamyl transferase were increased greatly. Albumin, plasma protein, urea and bilirubin levels were decreased in kava users, and high-density lipoprotein cholesterol levels were increased. Kava users were more likely to show haematuria, and to have urine which was poorly acidified and of low specific gravity. The use of kava was also associated with an increased red-cell volume, with a decreased platelet volume and with a decreased lymphocyte count. Shortness of breath in kava users was associated with tall P waves on a resting electrocardiogram, which provided suggestive evidence of pulmonary hypertension. In common with other Aboriginal communities, there was evidence of decreased lung volumes, a high carriage rate of hepatitis B surface antigen, and of other morbidity that was unrelated to the use of kava. On the basis of these findings, there is a strong rationale for urgent social action to improve health in Aboriginal communities and, in particular, to reduce the consumption of kava and to improve the nutritional status of kava users.

Adolescent↗
PubMed1988

Immune complexes and Ross River virus disease (epidemic polyarthritis).

Immune complexes were sought in serum and synovial fluid in Ross River virus disease (epidemic polyarthritis). Multiple samples from 15 patients showing varied degrees of disease activity over a 3 month period were analysed for their content of complement components C3 and C4, and for C1q solid-phase and Raji cell binding activity. Levels of C3 and C1q binding activity were normal. C4 and Raji cell binding activity were normal except for three high levels of Raji cell binding, of which two were accompanied by low levels of C4, with normal C3 and C1q binding. Synovial fluid showed anomalous Raji cell reactivity of uncertain significance. Conglutinin solid-phase binding activity and IgG rheumatoid factor were compared in the serum of 20 patients during active disease and after recovery. The results were identical and within the normal range in both phases. One patient developed IgM rheumatoid factor in a low titre late in his illness. Although these findings do not entirely exclude a role for immune complexes formed at the onset in the circulation or tissues, it is concluded from this and other evidence that circulating complexes are not commonly responsible for the persistence of syndromes in this disease.

Antigen-Antibody Complex↗
PubMed1987

Human immunoglobulin variable region genes: a new VH sequence used to detect polymorphism.

A human heavy chain variable region subgroup III pseudogene (HV3.3) was isolated, characterized, and sequenced. When HV3.3 was hybridized to Southern blots of human DNA, two potentially informative polymorphic bands, resulting from 2.7 kb Hind III (HH2.7) and 7.3 kb Eco RI (HE7.3) fragments, were detected with frequencies of 0.553 and 0.606, respectively. These polymorphic bands showed Mendelian segregation in families and appeared to be in tight linkage disequilibrium with each other (chi 2(1) = 24.91, P less than 0.001). Evidence from sibling-pair data indicated linkage of the Hind III polymorphic band to constant region allotypic and restriction fragment length polymorphism markers. Bands representing alternative forms of the polymorphic restriction sites were not detected for either HH2.7 or HE7.3. This indicates either that the alternative fragments comigrate with homologous fragments resulting from conserved restriction sites, or that the polymorphism is due to a gene duplication or deletion. No band segregating with HH2.7 was found in separate digests using eight other enzymes. Although this indicates that a major deletion or unlikely, it does not exclude the possibility of a gene deletion or duplication affecting the intergenic region(s) of one or more homologous genes. Whatever the precise explanation, these findings support the hypothesis that there is polymorphic variation of VH gene repertoires in man.

Genes↗
PubMed1987

Human immunoglobulin variable region genes: V kappa polymorphisms suggest variation in V-gene repertoires.

The present study characterizes four potentially informative polymorphic bands of 5.2, 2.3, 1.9, and 1.2 kb, detected by Southern blot hybridization of Eco RI digests of human DNA using HK101/80 (an immunoglobulin V kappa I probe). These restriction fragment length polymorphisms (RFLP) show Mendelian segregation and they are linked to each other and to Km(1), the allotypic marker on the kappa constant region. There is strong linkage disequilibrium between the 2.3 and 1.2 kb polymorphisms. A 0.7 kb Pst I polymorphic band and a 2.9 kb Sac I polymorphic band were also identified; the latter may reflect a region of tandem repeats in the V kappa region. No bands representing the alternative forms of any of the polymorphic restriction sites were identified. This implies either that genes are missing from the V kappa repertoire or that such bands are hidden because of comigration of fragments due to conservation of restriction sites. Evidence for comigration of fragments was obtained from independent V kappa clones and suggests that dark bands on Southern blots of Pst I digests must often represent several superimposed genes which have conserved restriction sites. The demonstration of RFLP within the V kappa region provides circumstantial evidence for polymorphic variation in the repertoire of V kappa structural genes. The RFLP reported here should be useful as genetic markers in future studies on the immune response and disease susceptibility in man.

Genes↗