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Biomedical subjects

J Kaldor

Publications and source records attributed to J Kaldor.

At least 37 records · Page 2Linked to original sources
PubMed1999

Investigation of a cluster of leukaemia in the Illawarra region of New South Wales, 1989-1996.

OBJECTIVES: To investigate a cluster of leukaemia among young people and assess the plausibility of a disease-exposure relationship. DESIGN: Descriptive analysis of population-based leukaemia incidence data, review of evidence related to the causation of leukaemia, assessment of environmental exposures to known leukaemogens, and resulting risks of leukaemia. SETTING: Illawarra region of New South Wales, Australia, focusing on suburbs between the Port Kembla industrial complex and Lake Illawarra (the Warrawong area). MAIN OUTCOME MEASURES: Standardised incidence ratios (SIRs) for leukaemia; current measured and past estimated ambient air benzene concentrations; and expected leukaemia cases attributable to estimates of ambient air benzene concentrations. RESULTS: In 1989-1996, 12 leukaemia cases among Warrawong residents aged less than 50 years were observed, more than the 3.49 cases expected from the rate in the rest of the Illawarra region (SIR, 343.8; 99% CI, 141.6-691.7). These people lived in suburbs immediately to the south-southwest of a coke byproducts plant (a major industrial source of benzene, one of the few known leukaemogens). The greatest excess was among 15-24-year-olds (SIR, 1085.6; 99% CI, 234.1-3072.4). In 1996, ambient air concentrations of benzene averaged less than 1 part per billion (ppb). Since 1970, ambient air concentrations of benzene were estimated to have averaged up to 3 ppb, about one-thousandth of the level at which leukaemia risk has been identified in occupational epidemiological studies. Using the risk assessment model developed by the US Environmental Protection Agency, we estimate that past benzene levels in the Warrawong area could have resulted in 0.4 additional cases of leukaemia in 1989-1996. CONCLUSIONS: The excess occurrence of leukaemia in the Warrawong area in 1989-1996 is highly unusual. Current environmental benzene exposure and the reconstructed past environmental benzene exposure level are too low to explain the large excess of leukaemia. The cause of the cluster is uncertain.

Adolescent↗
PubMed1999

Surgical treatment and risk of sporadic Creutzfeldt-Jakob disease: a case-control study.

BACKGROUND: Apart from the small number of iatrogenic and familial cases, the cause of most cases of Creutzfeldt-Jakob disease (CJD) is not known. We aimed to identify risk factors for sporadic CJD. METHODS: In a case-control study, we compared the medical history and selected demographic characteristics of 241 definite (neuropathologically confirmed) and probable (clinically likely) patients with CJD, ascertained from the Australian National Creutzfeldt-Jakob Disease Registry between Jan 1, 1970, and October 31, 1997, and of 784 controls, recruited from the community by random telephone interview in August, 1997. Standard logistic regression was used for the comparisons. FINDINGS: Surgical procedures were significantly associated with the development of sporadic CJD. This risk progressively increased with the number of surgical treatments to a maximum for three procedures (odds ratio 2.13 [95% Cl 1.34-3.41], p=0.002). There was also a significant association between risk of CJD and residence or employment on a farm (p<0.001) or market garden (p=0.002) for longer than 10 years. We found no significant risk associated with a history of blood transfusion, organ transplantation, major dental work, or occupation. INTERPRETATION: Our findings accord with the hypothesis that a range of surgical treatments may serve as unrecognised contamination events and account for a proportion of cases of sporadic CJD. Possible biases in different methods and times for the acquisition of data on cases and controls suggest our findings need to be replicated in independent studies with community controls.

Adolescent↗
PubMed1999

Seroprevalence of markers for hepatitis B, C and G in male and female prisoners--NSW, 1996.

OBJECTIVES: 1. Establish the prevalence of markers for hepatitis B (HBV), C (HCV) and G (HGV) in a sample of male and female inmates. 2. Examine exposure to multiple viruses. 3. Compare risk factors for HGV infection with known risk factors for HBV and HCV. DESIGN: Cross-sectional random sample stratified by sex, age and Aboriginality. Inmates were screened for three hepatitis markers. Participants were 789 inmates (657 male, 132 female) in 27 correctional centres in New South Wales, 1996. RESULTS: Overall detection of each of the three screening markers was 35% for HBV, 39% for HCV and 10% for HGV. Exposure rates were higher in female prisoners than males. Increased rates of anti-HBc were observed in Aboriginal inmates compared with non-Aboriginals (54% cf. 27%); anti-HCV and HGV-RNA were comparable between the two groups (36% cf. 41% and 9% cf. 10%). Markers were significantly higher in female injecting drug users (IDU), particularly HCV (90% cf. 66%). Thirty-five per cent of inmates were unaware of their HCV status. For HBV, 72% did not self-report past or present exposure despite serological evidence to the contrary. The multivariate analysis identified Aboriginality, long-term injecting and injecting while in prison as risk factors for HBV. HCV risk factors were female sex, non-Aboriginality, institutionalisation and IDU-associated behaviours. For HGV, female sex and previous imprisonment were significant risk factors but IDU was not. CONCLUSIONS: Blood-borne hepatitis viruses are common in prison inmates, particularly females (HBV, HCV and HGV), Aboriginals (HBV) and IDU (HBV and HCV). Infection can be related to a number of risk factors, which appear similar for HBV and HCV, but distinct from HGV.

Adolescent↗
PubMed1999

Serum antibody response to Cryptococcus neoformans in cats, dogs and koalas with and without active infection.

Anti-cryptococcal antibodies were measured in normal cats, dogs, horses and koalas, and cats, dogs and koalas with cryptococcosis using an enzyme immunoassay. Antibody levels were expressed as absorbance readings. Over 80% of cats and dogs with cryptococcal infection had elevated antibody levels at the time of diagnosis, during or after successful therapy. Antibody levels in these patients either remained elevated or declined slowly after treatment. For cats, anti-cryptococcal antibody levels were higher in C. neoformans var. gattii than var. neoformans infections, and lower in mild than in moderate or severe infections. The persistence of increased anti-cryptococcal antibody levels in over half of the feline and canine cases following active infection suggested the use of antibody determinations as a seroepidemiologic marker of previous infection. Consequently, antibody measurements from 'normal' animals indicated a prevalence of previous cryptococcal infection of 10% in cats and dogs, compared with 3% in horses and 5% in koalas. Preliminary studies of young animals suggested that anti-cryptococcal antibody levels were substantially lower in the young cats but not the young dogs surveyed, compared with their mature counterparts. The cut-offs used in the present work may thus be erroneously high, with a corresponding underestimation of the prevalence of inapparent cryptococcosis.

Aging↗
PubMed1998

Cultures of sexual adventurism as markers of HIV seroconversion: a case control study in a cohort of Sydney gay men.

A case control analysis within an ongoing cohort study was used to examine differences between seroconverters and men who remained HIV-negative. The cases were interviewed within one to 13 months prior to their seroconversion. Their responses to a structured questionnaire were compared with those of HIV-negative controls drawn from the same time period and from the same longitudinal study, Sydney Men and Sexual Health. Data collected from both cases and controls included: demographic and contextual variables, knowledge of HIV transmission, sexual practices, drug and alcohol use and attitudinal factors. The aim was to compare the sexual behaviours, and the social and cultural contexts of such behaviours, of men prior to their HIV seroconversion with men who did not seroconvert. Twenty-three men had seroconverted within the cohort. Cases were identified by a positive HIV antibody test or self-report of positive HIV status following a previous negative HIV test. Three-hundred-and-sixty-nine controls were selected on the basis of being HIV negative at interview in 1994, and having at least one subsequent medically-confirmed negative HIV antibody test. Univariate predictors of seroconversion were: being in a regular relationship with a known HIV-positive partner, drug use, and engaging in a range of anal and esoteric sexual practices. Practices commonly used to enhance sexual pleasure, such as group sex, watching and being watched having sex, the use of sex toys and dressing up/fantasy, were engaged in more frequently by seroconverters. Engaging in these esoteric sexual practices was highly correlated with drug use, involvement in the gay community and engagement in a wide range of anal practices. In the multivariate analysis independent predictors of seroconversion were: younger age; being in a regular relationship with a known HIV-positive partner; believing withdrawal to be safe with regard to HIV transmission; and range of esoteric practices. These results indicate the importance of the social and cultural contexts of particular sexual practices and consequent HIV transmission. Sexually adventurous men may be at increased risk for HIV because they seek sex within particular sexual sub-cultures.

Adult↗
PubMed1998

AIDS impact.

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Acquired Immunodeficiency Syndrome↗
PubMed1998

Cisplatin-DNA adducts and protein-bound platinum in blood of testicular cancer patients.

DNA adducts formed by cisplatin [cis-diamminedichloroplatinum(II)] were measured in blood samples from 48 testicular cancer patients treated in four centers in Europe during four to six cycles with cisplatin infusions on five successive days (total samples, 112). Total protein-bound platinum (Pt) in blood was also measured (total samples, 84). The mean on the main DNA adduct, cis-Pt(NH3)2d(pGpG) (Pt-GG), was 0.75 fmol/microg DNA [standard deviation (SD) = 0.66] on the first day of the first cycle, increased after the infusion at day 5 of the cycle (mean 1.74 fmol/microg DNA, SD = 0.90) and decreased on the following day (mean 1.09 fmol/microg DNA, SD = 0.62). In subsequent cycles, there was a tendency to an increase in the mean Pt-GG levels. The values of protein-bound Pt in blood showed little reduction between day 5 and 6 of each cycle, and a stable increase during the course of the therapy. Strong correlations were seen between day 1, 5 and 6 of the first cycle for both Pt-GG and protein-bound Pt in blood. A strong correlation (r = 0.62, p < 0.001, 69 pairs) was found between the levels of Pt-GG and protein-bound Pt. Only two patients relapsed during the follow-up; therefore, the analysis of the association between Pt-GG levels and response to therapy was not informative. The results of this study suggest that DNA adducts formed by cisplatin at the beginning of chemotherapy are predictive of values found during later days and cycles, and that the value of protein-bound Pt in blood is predictive of the value of DNA adducts.

Adult↗
PubMed1998

Changing pattern of delays in reporting AIDS diagnoses in Australia.

To accurately monitor and predict the progress of the HIV/AIDS epidemic, it is important to adjust reported AIDS counts for reporting delays. This requires estimation of the reporting delay distribution. This paper aims to use a statistical model to identify the main factors influencing reporting delays in Australia and to adjust reported incidence data for these delays among cases of AIDS diagnosed from 1993 and reported before 30 June 1997. Reporting delays were found to vary significantly across states/territories. The influence of calendar time of diagnosis was also significant, with an overall trend toward longer delays over time. AIDS cases diagnosed in the fourth quarter of a year were reported significantly more quickly than those diagnosed in the first or third quarters. No significant differences were found due to sex, age and HIV exposure category, except people with haemophilia, in whom AIDS cases appeared to be reported more slowly. After adjusting for under-reporting and reporting delay, we found that the AIDS incidence in Australia was declining from about 1000 cases per year in 1994 to about 760 cases per year in 1996.

Acquired Immunodeficiency Syndrome↗
PubMed1998

HIV and HCV prevalence among trawler crew.

A survey of 51 people who work on trawlers was carried out to describe injecting and sexual behaviour and the prevalence of HIV and HCV antibody. All crew members who were departing from an Australian port during the last week of February 1996 to work on trawlers were asked to complete a brief, self-administered questionnaire and provide a finger prick blood sample. Questionnaires were received from 51 (77%) and blood samples from 45 (68%) of the 66 crew from 15 vessels. Almost half the respondents reported ever injecting illicit drugs. No respondents had HIV antibody while 27% had HCV antibody detected. Among 20 injecting drug user (IDU) respondents, the prevalence of HCV was 55% (95% CI 32%-77%). Twelve respondents reported new sex partners in the past month of whom half reported no condom use with these sex partners. The survey emphasises the diversity of the IDU population in Australia. Yet it would appear that regardless of the sub-population surveyed that HCV is endemic among IDUs in Australia. Effective HCV prevention programs targeted specifically for these (and other) sub-populations of IDUs should be devised.

Adolescent↗
PubMed1997

Sexual practices in a broad cross-sectional sample of Sydney gay men.

The aim of this study was to provide current data on the sexual practices in a broad cross-sectional sample of gay and homosexually active men in Sydney. Anonymous, short questionnaires were completed by 1611 gay men recruited at the 1996 Gay and Lesbian Mardi Gras Fair Day or at one of six venues (including two sexual health centres) across the metropolitan area during the following week. The sample was diverse, but the men tended to be of Anglo-Australian background, well educated, professionally employed, attached to gay community and gay identified. They mainly had sex with other men rather than with men and women. Most (86.0 per cent) had been tested for human immunodeficiency virus. Excluding 241 men recruited in sexual health centres, 11.2 per cent were HIV-positive and 73.4 per cent were negative. Where it occurred in regular relationships, unprotected anal intercourse was usually between seroconcordant partners (78.5 per cent). Unprotected anal intercourse between discordant or nonconcordant regular partners was much less common, and in about half the cases involved withdrawal prior to ejaculation exclusively rather than ejaculation inside. Almost 12 per cent of the men had at least 'occasionally' engaged in unprotected anal intercourse with a casual partner in the previous six months, with approximately half of these men having adopted a withdrawal strategy on every occasion. We conclude that short surveys can provide valuable and timely data on sexual practices in a broad cross-sectional sample of gay and homosexually active men. Key messages for those involved in gay men's education are the high rates of unprotected anal intercourse between casual partners and the extensive practice of withdrawal.

Adolescent↗
PubMed1997

Epidemiology of hepatitis C virus infection among injecting drug users in Australia.

STUDY OBJECTIVE: To review the epidemiology of hepatitis C virus (HCV) infection among injecting drug users (IDUs) in Australia, and consider needs for further research and prevention policies and programmes. DESIGN: (1) Review of the results of surveillance for HCV; (2) review of published literature on prevalence, incidence, and risk factors for HCV among IDUs; and (3) reconstruction of incidence rates from prevalence studies of HCV in IDUs. SETTING AND PARTICIPANTS: Field and clinic based studies of IDUs in Australia. MAIN RESULTS: HCV has been present at high prevalences (of the order of 60-70%) in populations of Australian IDUs since at least 1971. Duration of injecting and main drug injected were the main predictors of seropositivity, the latter possibly a surrogate for frequency of injecting and both together as surrogate for cumulative numbers of times injected. Risk of infection begins with first injection and continues as long as injecting does. Current incidence is approximately 15 per 100 person years, and up to 40 per 100 person years in some subpopulations. Incidence may have decreased through the 1980s as a result of behaviour change in relation to HIV, as it has for hepatitis B, but not significantly so. CONCLUSIONS: Control of HCV infection in Australia will depend on effectiveness of measures to control HCV spread among IDUs. This will be a greater challenge than the control of HIV in this population has been. Needs identified include improved surveillance, especially for recently acquired infection, better understanding of exact transmission modes, and urgent improvement in prevention strategies.

Adult↗
PubMed1997

Herpes zoster and the stage and prognosis of HIV-1 infection.

OBJECTIVES: To examine the incidence of herpes zoster in HIV-1 infection. To assess the prognostic significance of the occurrence of herpes zoster and progression to AIDS or death DESIGN AND METHODS: 146 homosexually active men with known times of HIV-1 seroconversion were identified through the Sydney AIDS Prospective Study and the clinic records of a private medical practice with large caseload of HIV infected homosexual men. Medical records were reviewed for a history of herpes zoster, CD4+ lymphocyte counts, and HIV-1 disease status. Cox's proportional hazards model was used to determine whether herpes zoster predicted progression to AIDS or death. RESULTS: After a mean follow up of 54 months, 30 men (20%) had an episode of herpes zoster and three of these men had one recurrence. The overall incidence of herpes zoster was 44.4 episodes per 1000 person years (95% CI 30.0-63.5). Herpes zoster was not found to be a marker of deteriorating immune functions as measured by CD4+ lymphocyte counts. CD4+ counts did not differ significantly between those with and without zoster at 1 year (551 v 572.10(6)/1, p = 0.79), 2 years (451 v 557, p = 0.11), and 3 years (424 v 481, p = 0.50) following HIV-1 seroconversion. There was no statistically significant difference in progression to AIDS (RR = 1.89, 95% CI 0.80-4.46, p = 0.15) or death (RR = 0.90, 95% CI 0.31-2.65, p = 0.85) from HIV-1 sero-conversion in those who did and those who did not develop herpes zoster. CONCLUSION: The incidence of herpes zoster was consistent with the findings of other studies. There was no association between the occurrence of herpes zoster and progression of HIV-1 disease.

AIDS-Related Opportunistic Infections↗
PubMed1996

Primary infection with zidovudine-resistant human immunodeficiency virus type 1 does not adversely affect outcome at 1 year. Sydney Primary HIV Infection Study Group.

Human immunodeficiency virus type 1 (HIV-1) variants with reduced in vitro sensitivity to zidovudine, conferred by specific mutations in the viral reverse transcriptase, emerge during prolonged therapy. Late-stage disease and declining CD4 cell count are associated with more rapid emergence of these resistant variants. Isolates of HIV-1 from seroconverters were screened for the zidovudine-resistance marker mutation at codon 215. HIV-1 with the altered genotype was detected in 5 (8.2%) of 61 patients soon after onset of symptomatic primary illness and from the sex partner of 1 patient. These transmitted resistant viruses were either replaced by strains susceptible to zidovudine within a few months of infection or persisted for up to 1 year in the absence of prolonged zidovudine therapy. The resistant genotype persisted in 3 of 5 seroconverters but in 2 patients had reverted to wild type at 48 and 52 weeks. Primary infection with zidovudine-resistant variants of HIV-1 was not associated with a more severe symptomatic primary illness or more rapid CD4 cell decline at 1 year after infection.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Predictive markers of AIDS dementia complex: CD4 cell count and cerebrospinal fluid concentrations of beta 2-microglobulin and neopterin.

A predictive marker for AIDS dementia complex (ADC) in a cohort of neurologically asymptomatic human immunodeficiency virus type 1 (HIV-1)-infected patients with < 200 CD4 cells/microL was sought. Patients were assessed neurologically and neuropsychologically at entry. Blood and cerebrospinal fluid (CSF) were taken for assay of beta 2-microglobulin (beta 2M), and neopterin and T cell subsets were assessed from blood. Patients were evaluated every 4 months. Of 37 patients recruited, 35 had sufficient follow-up data. Seventeen patients progressed to ADC stage > or = 1. In univariate analyses, concentrations of CSF beta 2M and neopterin and CD4 cell count were each significantly associated with ADC development. In a multivariate analysis, concentrations of CSF beta 2M remained significant, with levels > 5 mg/L carrying approximately 17 times the risk of ADC. CSF beta 2M and neopterin levels and CD4 cell count are useful in identifying patients at risk of ADC and as such can be used to target high-risk patients so therapy can be optimized.

AIDS Dementia Complex↗