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Biomedical subjects

Andrew J Hall

Publications and source records attributed to Andrew J Hall.

45 records · Page 3Linked to original sources
PubMed2002

Contacts with varicella or with children and protection against herpes zoster in adults: a case-control study.

BACKGROUND: Whether exogenous exposure to varicella-zoster-virus protects individuals with latent varicella-zoster virus infection against herpes zoster by boosting immunity is not known. To test the hypothesis that contacts with children increase exposure to varicella-zoster virus and protect latently infected adults against zoster, we did a case-control study in south London, UK. METHODS: From 22 general practices, we identified patients with recently diagnosed zoster, and control individuals with no history of zoster, matched to patients by age, sex, and practice. Participants were asked about contacts with people with varicella or zoster in the past 10 years, and social and occupational contacts with children as proxies for varicella contacts. Odds ratios were estimated with conditional logistic regression. FINDINGS: Data from 244 patients and 485 controls were analysed. On multivariable analysis, protection associated with contacts with a few children in the household or via childcare seemed to be largely mediated by increased access to children outside the household. Social contacts with many children outside the household and occupational contacts with ill children were associated with graded protection against zoster, with less than a fifth the risk in the most heavily exposed groups compared with the least exposed. The strength of protection diminished after controlling for known varicella contacts; the latter remained significantly protective (odds ratio 0.29 [95% CI 0.10-0.84] for those with five contacts or more). INTERPRETATION: Re-exposure to varicella-zoster virus via contact with children seems to protect latently infected individuals against zoster. Reduction of childhood varicella by vaccination might lead to increased incidence of adult zoster. Vaccination of the elderly (if effective) should be considered in countries with childhood varicella vaccination programmes.

Adolescent↗
PubMed2002

Validation of immunoglobulin G enzyme-linked immunosorbent assay for antibodies to pneumococcal surface adhesin A in the diagnosis of pneumococcal pneumonia among adults in Kenya.

Epidemiologic studies of pneumococcal pneumonia, including vaccine efficacy trials, are hampered by a lack of sensitive and specific diagnostic tests. Pneumococcal surface adhesin A (PsaA) is a genetically conserved, surface-expressed protein common to all serotypes of Streptococcus pneumoniae and is highly immunogenic. Detection of anti-PsaA immunoglobulin G by recombinant PsaA enzyme-linked immunosorbent assay was evaluated for diagnosis of pneumococcal pneumonia in paired serum samples from 4 adult populations: 47 healthy control subjects, 56 clinic control subjects without pneumococcal disease syndromes, 109 patients with pneumococcal pneumonia, and 93 pneumonia patients with no evidence of pneumococcal etiology. By considering a 2-fold increase in antibody concentration as positive, sensitivity was 0.70, and specificity was 0.98. With a 1.3-fold increase, these were 0.89 and 0.98, respectively. The test's performance was not affected by the patients' human immunodeficiency virus status or by the pneumococcal serotype. The combination of high sensitivity and high specificity makes this an ideal assay for epidemiologic studies of pneumococcal pneumonia.

Adolescent↗
PubMed2002

Evaluation of adverse effects of vaccines: the case-control approach.

When the hypothesis of a link between vaccination and a possible adverse outcome arises, further investigation is required to confirm or refute the suspicion. Given the rarity of most serious adverse effects, a case-control approach will often be chosen. This paper discusses aspects of the design, analysis and interpretation of case-control studies to evaluate vaccine adverse effects. Potential biases (and how to minimise such biases) in the selection of cases and assessment of vaccine exposure and the potential for confounding are discussed. Finally the increasing use of electronic databases in the evaluation of vaccine adverse effects is considered.

Case-Control Studies↗
PubMed2002

The role of aflatoxins and hepatitis viruses in the etiopathogenesis of hepatocellular carcinoma: A basis for primary prevention in Guinea-Conakry, West Africa.

Aflatoxins and hepatitis B virus (HBV) are major risk factors for hepatocellular carcinoma (HCC) in South-east Asia and Africa, parts of the world where this cancer is most prevalent. Exposure to both factors is endemic, occurring from early in life. There is evidence from both epidemiological studies and animal models that the two factors can act synergistically to increase the risk of HCC, but the underlying cellular and molecular mechanisms of interaction are as yet undefined. One possibility suggested by studies in HBV transgenic mice is that chronic liver injury alters the expression of carcinogen metabolizing enzymes, thus modulating the level of binding of aflatoxin to DNA. Primary prevention of HCC in high incidence areas of the world should primarily be focused on provision of the safe, effective vaccine against HBV. However, measures to reduce the high levels of aflatoxin exposure, where chronic HBV infection is currently epidemic, would also significantly contribute to reducing HCC incidence. In Guinea-Conakry, West Africa, surveys of HBV infection and aflatoxin exposure have established baseline data for the implementation of a community-based intervention study. This study will evaluate the effectiveness of improving the post-harvest processing and storage of the groundnut crop, a major source of aflatoxins, using aflatoxin-albumin adducts as the outcome measurement.

Aflatoxins↗
PubMed1998

Intra-rater and inter-rater reliability of a weight-bearing lunge measure of ankle dorsiflexion.

This study aimed to evaluate the inter-rater and intra-rater reliability of a weight-bearing dorsiflexion (DF) lunge in 13 healthy subjects. Our raters with varying clinical experience tested all subjects in random order. Two of the raters repeated the measurements one week later. Two methods were used to assess the DF lunge: (i) the distance from the great toe to the wall and (ii) the angle between the tibial shaft and the vertical using an inclinometer. The average of three trials was used in data analysis. Intra-rater intraclass correlation coefficients (iccs) ranged from 0.97 to 0.98. Inter-rater ICC values were 0.97 (angle) and 0.99 (distance). results indicate excellent reliability for both methods of assessing a DF lunge.

Journal Article↗
PubMedDate not supplied

MMR vaccination and pervasive developmental disorders: a case-control study.

BACKGROUND: Concern that measles-mumps-rubella (MMR) vaccination might cause autism has led to a fall in vaccine coverage. We investigated whether MMR vaccination is associated with an increased risk of autism or other pervasive developmental disorders. METHODS: We did a matched case-control study using the UK General Practice Research Database. Cases were people born in 1973 or later who had first recorded diagnosis of pervasive developmental disorder while registered with a contributing general practice between 1987 and 2001. Controls were matched on age, sex, and general practice. FINDINGS: 1294 cases and 4469 controls were included. 1010 cases (78.1%) had MMR vaccination recorded before diagnosis, compared with 3671 controls (82.1%) before the age at which their matched case was diagnosed. After adjustment for age at joining the database, the odds ratio for association between MMR and pervasive developmental disorder was 0.86 (95% CI 0.68-1.09). Findings were similar when restricted to children with a diagnosis of autism, to those vaccinated with MMR before the third birthday, or to the period before media coverage of the hypothesis linking MMR with autism. INTERPRETATION: Our findings suggest that MMR vaccination is not associated with an increased risk of pervasive developmental disorders.

Asperger Syndrome↗