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Biomedical subjects

A J Hall

Publications and source records attributed to A J Hall.

At least 19 recordsLinked to original sources
PubMed1992

The descriptive epizootiology of phocine distemper in the UK during 1988/89.

The 'time, place, individual' approach, widely used in characterising human epidemics, was applied to the 1988 phocine distemper virus (PDV) epizootic affecting North Sea seals. Estimates of time of death from 157 (69%) of the 228 dead seals necropsied in 1988 indicated that the number of carcasses which were found more than 14 days post mortem increased as the epizootic progressed. Although information provided by epizootic curves based on when and where carcasses were reported are affected by the accuracy of such data, the PDV epizootic curves were characteristic of a propagative epidemic. The individual characteristics of the carcasses provided more useful information. 1. Common seals were more susceptible than grey seals. 2. Males and older seals had a greater exposure to the virus than females and younger animals. 3. The likelihood of viral transmission was greater on land. Seasonal, sex and age related variation in haul-out behaviour affected transmission probabilities and rates. 4. The risk of infection for a susceptible individual during August was higher for seals in England and Northern Ireland than for those in Scotland. These findings illustrate the importance of population characteristics including behaviour and social organisation in determining the pattern and spread of wildlife epizootics.

Animals↗
PubMed1992

Organochlorine levels in common seals (Phoca vitulina) which were victims and survivors of the 1988 phocine distemper epizootic.

We compared concentrations of organochlorines in the blubber of common seals (Phoca vitulina) found dead during the 1988 phocine distemper epizootic with levels in animals which survived it. There were highly significant differences between the live and dead animals, and between sample sites. These were not fully accounted for by seasonal and condition-related changes in blubber thickness.

Adipose Tissue↗
PubMed1992

KY nailing of impending and pathological fractures of the proximal femur.

Eight two patients underwent 86 Küntscher Y nailing for impending and pathological fractures of the proximal femur. All but five mobilised post-operatively, thus improving their quality of life. Eighteen patients died in hospital. Prophylactic nailing improved survival. Fifteen out of 86 nailings were followed by complications.

Aged↗
PubMed1992

Aflatoxin M1 in human breast milk from The Gambia, west Africa, quantified by combined monoclonal antibody immunoaffinity chromatography and HPLC.

Maternal to child exposure of aflatoxin M1 in breast milk is an underevaluated risk factor from dietary exposure to aflatoxin B1. A molecular dosimetry study in The Gambia, West Africa, was initiated to explore the relationships between dietary intake of aflatoxins during a 1 week period and a number of aflatoxin biomarkers including aflatoxin metabolite excretion into breast milk. For the breast milk study, five lactating women were identified and milk samples were collected by hand expression once a day during days 3-7 for three women and during days 3-6 for the two other women. Aflatoxin M1 (AFM1) in human milk was measured in all five subjects by a preparative monoclonal antibody immunoaffinity column/HPLC method. In three of the five women, aflatoxin G1 was found. Estimates of the percentage of aflatoxin in the diet excreted as AFM1 in milk ranged from 0.09 to 0.43%. Thus, these data indicate that a rapid methodology exists to assess the levels of AFM1 excretion in human milk and to use this approach as a biomarker for exposure of children to this carcinogen.

Aflatoxin M1↗
PubMed1992

The Gambia Hepatitis Intervention Study: follow-up of a cohort of children vaccinated against hepatitis B.

Hepatitis B vaccine has been introduced into The Gambia's national Expanded Programme on Immunization, with the aim of evaluating the impact on chronic liver diseases and in particular on hepatocellular carcinoma. As part of the project, a cohort of 1000 children was recruited to assess the long-term protection induced by the vaccine. The first 3 years of follow-up are described. By the age of 3 years, 95% of the children had protective antibody levels; 4 (0.6%) are known to be carriers in contrast to the 90-140 that would be expected in the absence of vaccination. The protective effectiveness of vaccine in preventing chronic carriage in the first 3 years of life is thus estimated as 95%. Since the risk of becoming a carrier is highest in those infected early in life, these results are encouraging.

Antigens, Viral↗
PubMed1992

The Epping jaundice outbreak: a 24 year follow up.

STUDY OBJECTIVE: The aim was to trace 84 cases of jaundice that occurred following accidental ingestion of methylene dianiline (MDA) in Epping in 1965, and to look at long term health effects. DESIGN: The original case notes of the cases were used to identify the patients. Subsequent tracing procedures included local general practitioners, the Central NHS Registry, electoral rolls, and company records. SETTING: This was a community based survey. MAIN RESULTS: The health status of 68 (81%) of the group was established with 18 deaths. Of the 50 cases known to be alive, 58% completed a health questionnaire. The causes of death were unremarkable except for one case of carcinoma of the biliary tract. Two surviving cases had suffered retinal pathology. Four other surviving cases had had a further, perhaps unrelated, episode of jaundice. CONCLUSIONS: Although the dose and route of administration in the epidemic differed from occupational exposure, this follow up study a generation on provides little, if any, evidence of long term health sequelae. Nevertheless, in the absence of well documented exposure and health effects data, such accidental poisonings with proven animal carcinogens warrant long term follow up. The identified cohort will be the subject of further study.

3,4-Methylenedioxyamphetamine↗
PubMed1992

Conditioning of Nude bone marrow increases in vitro migration to thymus supernatant.

The thymus must be continuously seeded by cells termed prothymocytes in order to maintain normal T-cell development (Scollay et al. 1986). Using parabiotic studies, the source of prothymocytes appears to be either from the fetal liver or the adult bone marrow (Roderwald et al. 1992). The ability of the body to distinguish self from non-self and mount a functionally mature immune response is dependent upon the intrathymic education of these cells. Therefore, it is apparent that successful migration of prothymocytes into the thymus is an inescapable event in the development and maintenance of the immune system. Utilization of the athymic Nude mouse is a valuable asset in the elucidation of the mechanisms influencing the migration of bone marrow cells into the thymus. Its aberration enables investigators to examine the effect of thymic factors on cells previously devoid of thymic influence. In an attempt to understand the migration of normal prothymocytes into the thymus, we analyzed the in vitro migration of athymic bone marrow cells towards newborn thymus supernatant. Adult athymic murine bone marrow cells were incubated in either thymus supernatant or media and allowed to migrate toward one or the other. Similar control experiments were performed using CBA adult mice. Results indicate that athymic bone marrow migration towards both supernatant and media can be restored to control levels after incubation in thymus supernatant.

Animals↗
PubMed1992

HIV-1 and HIV-2 seroprevalence rates in mother-child pairs living in The Gambia (west Africa).

A seroepidemiological study was conducted, during 1988 and 1989, of mother-child pairs living in The Gambia (West Africa) in order to determine the distribution of the human immunodeficiency viruses type 1 (HIV-1) and type 2 (HIV-2). Specimens were obtained from 931 children (age range, 14-17, months) and 923 mothers (age range, 14-17 years) using village-based cluster samples; the children are participating in The Gambia Hepatitis Intervention Study (GHIS), a large-scale HBV vaccination program. Large numbers of indeterminate Western blot patterns were observed among the mothers, mainly for HIV-1 antibodies; HIV-1 infected subjects were not found, whereas an HIV-2 seroprevalence rate of 0.75% was observed. The children born to the seven HIV-2 positive women were seronegative for HIV-2 antibodies, and none of the children showed HIV-2 or HIV-1 seropositively.

Adolescent↗
PubMed1991

The effect of insecticide-treated bed nets on mortality of Gambian children.

Insecticide treatment of bed nets ("mosquito nets") may be a cheap and acceptable method of reducing the morbidity and mortality caused by malaria. In a rural area of The Gambia, bed nets in villages participating in a primary health-care (PHC) scheme were treated with permethrin at the beginning of the malaria transmission season. Additionally, children aged 6 months to 5 years were randomised to receive weekly either chemoprophylaxis with maloprim or a placebo throughout the malaria transmission season. We measured mortality in children in PHC villages before and after the interventions described, and compared this with mortality in villages where no interventions occurred (non-PHC villages). About 92% of children in PHC villages slept under insecticide-treated bed nets. In the year before intervention, mortality in children aged 1-4 years was lower in non-PHC villages. After intervention, the overall mortality and mortality attributable to malaria of children aged 1-4 in the intervention villages was 37% and 30%, respectively, of that in the non-PHC villages. Among children who slept under treated nets, we found no evidence of an additional benefit of chemoprophylaxis in preventing deaths. Insecticide-treated bed nets are simple to introduce and can reduce mortality from malaria.

Antimalarials↗
PubMed1991

Vaccination against hepatitis B and protection against chronic viral carriage in The Gambia.

358 children in the Gambian villages of Keneba and Manduar, where hepatitis B virus (HBV) infection is endemic, were vaccinated with plasma-derived vaccine against HBV according to one of four regimens and followed for up to 4 years. Two regimens by which vaccine was injected intradermally into children between 0 and 4 years old led to peak geometric mean (95% CI) concentrations of antibody against HBV surface antigen of 270 (202-358) and 555 (418-748) mlU/ml. The third regimen--intramuscular vaccination of children aged between 0 and 4 years--gave geometric mean peak antibody concentrations of 926 (765-1122) mlU/ml. A fourth regimen was intramuscular vaccination of children between 1 and 9 months old, which gave geometric mean antibody concentrations of 5431 (3903-75,456) mlU/ml. Despite these widely divergent responses and a 89% decay in antibody over the first 2 years, vaccination against HBV was 97% effective in preventing chronic infection. Vaccination was less effective in preventing uncomplicated infection: 5.3% of 264 vaccinees in Keneba and 19.1% of 94 vaccinees in Manduar tested positive for antibody to HBV core antigen. These "breakthrough infections" did not differ in frequency between regimens, and were associated with low initial antibody responses and chronic maternal carriage of HBV.

Adolescent↗