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Biomedical subjects

L London

Publications and source records attributed to L London.

At least 19 recordsLinked to original sources
PubMed1996

Respiratory-mucosal lymphocyte populations induced by reovirus serotype 1 infection.

Respiratory virus infections are a serious health challenge. While models exist to study immune mechanisms of the respiratory tract, they have not allowed analysis of the interaction of the lower respiratory tract with other components of the mucosal immune system. This study demonstrates that reovirus 1/Lang, an effective gut mucosal immunogen, also provides a useful model of respiratory mucosal infection. Intra-nasal infection of Balb/c mice resulted in severe viral bronchopneumonia. Major components of the cellular inflammatory response in the lung interstitium and alveolar spaces were CD8 lymphocytes. Lung lymphocyte populations exhibited lysis of reovirus-infected, but not uninfected target cells after in vitro culture. The GCT antigen, a germinal center B-cell and CD8 T-cell marker, was present on 21-60% of the inflammatory lymphocytes. A novel population of GCT-expressing CD4+ lymphocytes unique to reovirus-stimulated lung alveolar and interstitial lymphocyte populations was identified.

Acute Disease↗
PubMed1996

Infant mortality rate inequalities in the Western Cape Province of South Africa.

BACKGROUND: Cape Town is undergoing rapid urbanization. South African vital statistics have routinely been stratified by racial categories but intra-urban and peri-urban geographical variations have been neglected. METHODS: To examine variations in infant mortality rates (IMR) and proportional infant mortality between urban, rural and informally settled areas, stratified by racial category, birth notifications and infant death certifications recorded by a large health authority were analysed. RESULTS: The IMR per 1000 livebirths was as high for coloureds on rural farms (34, 95% confidence interval 29-40) as for blacks in informal settlements (35, 95% CI: 32-37) and an exceptionally high IMR (60, 95% CI: 43-82) was found for coloureds in informal settlements. Inequalities between racial categories (11 (95% CI: 9-14) for whites, 19 (95% CI: 18-21) for coloureds and 33 (95% CI: 31-35) for blacks) were as expected from other South African studies. Of rural farm deaths, 22% were ascribed to ill-defined causes. Low birthweight was the most common defined cause of death in all areas except rural farm areas (14% ascribed to pneumonia), and gastro-enteritis was important in informally settled areas (18%). CONCLUSIONS: Routine mortality data are more informative if stratified by robust and readily available indicators of socio-economic status such as residential area and racial category. Place of residence may distinguish risk strata as well as racial category, but the latter is helpful within socioeconomically heterogeneous residential areas.

Black or African American↗
PubMed1996

AIDS programmes at the workplace: a scoresheet for assessing the quality of services.

Little data is available on the extent or comprehensiveness of AIDS prevention activities at South African workplaces. A cross-sectional postal survey was performed of all members of the local occupational health nursing association in the area of greater Cape Town in 1994 to assess the quality of such programmes. Use was made of an index to score services based on their comprehensiveness, using criteria based on recommendations previously identified in the South Africa literature on AIDS control. The presence of a workplace policy on AIDS was the strongest predictor of high quality AIDS prevention activities. Substantial numbers of companies reported sending staff for HIV-related training, and the presence of training was non-significantly associated with higher quality services with regard to HIV prevention. Treatment of sexually-transmitted diseases (STDs) was reported in slightly over half of the sample. Given the central importance of STD treatment for the prevention and control of AIDS, improvements in STD management at the workplace may significantly assist attempts at the public health control of the HIV epidemic. In addition, worker involvement in the planning, management and implementation of AIDS prevention activities is also limited at present and needs attention. Recommendations for the use of a scoring system to promote evaluation of AIDS programmes in the workplace are made.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Experimental reovirus serotype 1/strain Lang infection of the lung: a model for the study of the lung in the context of mucosal immunity.

A number of studies have examined the nature of the respiratory immune response to particular pathogens. Although many pathogens stimulate specific immunity in the lung, they frequently are not effective immunogens at other mucosal sites. Because the gastrointestinal tract is a major inductive site for mucosal immunity, a pathogen that is an effective respiratory and gut immunogen would allow studies of the interaction of the lung with gut mucosal immune system. Reovirus, a respiratory isolate that previously has been shown to be an effective gut mucosal immunogen, provides a potential model of the relationship of the lung to the gut mucosal immune system. In this report, we demonstrate that intranasal application of reovirus serotype 1/strain Lang (1/L) to CD-1 mice elicits an acute lymphocytic inflammatory infiltration of the lung and hyperplasia of the lung-associated lymph nodes. The initial inflammatory response occurs in the airspaces and interstitium of the lung. As the infection progresses, the initially diffuse cellular infiltrate becomes more focused around small bronchioles. Viral replication occurs predominantly during the first week of the infection, and infectious virions are eliminated during the second week. After the elimination of infectious virions, a secondary response consisting of the appearance of plasma cells adjacent to pulmonary arteries develops as the primary infiltrate organizes into peribronchiolar follicles, resembling the human inflammatory lung condition termed follicular bronchiolitis. These two infiltration patterns were also observed by immunohistochemical analysis of the the infected lung. Whereas CD4+ and CD8+ lymphocytes and Mac-1+ cells were found to be more closely associated with the primary infiltration process, B220+ lymphocytes were observed adjacent to pulmonary arteries. These results establish respiratory reovirus 1/L infection as a viable model for future investigations of the mucosal immune response in the lung and its relationship to the common mucosal immune system.

Animals↗
PubMed1995

Critical issues for agrichemical safety in South Africa.

A review is made of the potential for environmental and occupational exposure to agrichemicals in South Africa. Data from the farming industry in the Western and Southern Cape regions of South Africa confirm substantial use of a range of insecticides, fungicides, and other agrichemicals. The potential for worker exposure to hazardous agrichemicals is also substantial but, to date, such exposures have been poorly characterized. Further data identify important deficiencies in industrial hygiene measures with regard to safekeeping of chemicals on farms, disposal of empty containers, use of protective equipment, and levels of safety training among farm workers. Evidence is presented for widespread underreporting of agrichemical morbidity and mortality. Surveys investigating acute health effects among farm workers with occupational exposure to agrichemicals in South Africa have produced conflicting results. The possibility of chronic health sequelae from low-dose long-term exposure is an underresearched area that is only now being investigated. A number of important obstacles to agrichemical safety are identified: the multiplicity of laws relating to pesticides administered by different departments resulting in poor coordination; the failure of existing occupational health legislation to address the agricultural workplace adequately; the unavailability and incoordination of safety training; the absence of adequate surveillance data; and inadequacies in statutory requirements with regard to waste disposal on farms. Drawing on experiences of local initiatives, possible solutions are identified that address the public health context of the problem.

Chemistry, Agricultural↗
PubMed1995

Repeatability and validity of a field kit for estimation of cholinesterase in whole blood.

OBJECTIVES: To evaluate a spectrophotometric field kit (Test-Mate-OP) for repeatability and validity in comparison with reference laboratory methods and to model its anticipated sensitivity and specificity based on these findings. METHODS: 76 farm workers between the age of 20 and 55, of whom 30 were pesticide applicators exposed to a range of organophosphates in the preceding 10 days, had blood taken for plasma cholinesterase (PCE) and erythrocyte cholinesterase (ECE) measurement by field kit or laboratory methods. Paired blinded duplicate samples were taken from subgroups in the sample to assess repeatability of laboratory and field kit methods. Field kits were also used to test venous blood in one subgroup. The variance obtained for the field kit tests was then applied to two hypothetical scenarios that used published action guidelines to model the kit's sensitivity and specificity. RESULTS: Repeatability for PCE was much poorer and for ECE slightly poorer than that of laboratory measures. A substantial upward bias for field kit ECE relative to laboratory measurements was found. Sensitivity of the kit to a 40% drop in PCE was 67%, whereas that for ECE was 89%. Specificity of the kit with no change in mean of the population was 100% for ECE and 91% for PCE. CONCLUSION: Field kit ECE estimation seems to be sufficiently repeatable for surveillance activities, whereas PCE does not. Repeatability of both tests seems to be too low for use in epidemiological dose-response investigations. Further research is indicated to characterise the upward bias in ECE estimation on the kit.

Adult↗
PubMed1994

Notification of pesticide poisoning in the western Cape, 1987-1991.

There is a paucity of data on pesticide-related morbidity and mortality in South Africa. A review of notifications to the western Cape office of the Department of National Health and Population Development from 1987 to 1991 was undertaken to describe the epidemiological profile of pesticide poisoning in the region. Two hundred and twenty-five cases of pesticide poisoning were identified, of which the majority were from rural areas. Farmers, farm workers and their families were most frequently involved in poisoning events, which included accidents arising outside of workplace production (44%), self-inflicted injury (35%) and direct occupational contamination (11%). Farm pesticide stores were the most frequent source of pesticide and a seasonal variation in the trend of poisoning events could be discerned; this corresponded to agricultural spraying practices in the region. The mortality rate was significantly higher among those with self-inflicted injury, particularly farm workers. A concurrent review of hospital admissions for 1991 found that 78% of cases had not been notified. In view of the key role of surveillance in reducing pesticide-related morbidity and mortality, a call is made to improve notification of pesticide poisoning so as to facilitate control of an important potential public health problem.

Adolescent↗
PubMed1994

Agrichemical safety practices on farms in the western Cape.

In order to study agrichemical safety practices in a rural farming area in the western Cape, an audit of 45 randomly sampled farms was performed over 3 months in 1992. A response rate of 87% was achieved, and the survey results suggest that approximately 9% of permanent and 14% of seasonal farm workers are employed in jobs with potential exposure to agrichemicals. While protective equipment was widely available, gloves and masks were seldom used, with little enforcement or commercial support from the suppliers of the equipment. Farm workers receive little training on pesticide safety, but interest in the possibility of further training for workers was high. In the absence of a system of pesticide disposal, the presence of residual, unwanted and outdated stocks of pesticides in farmers' stores, and to a lesser extent the presence of empty containers, are identified as important problems. Current pesticide storage practices require improvement by simple industrial hygiene measures. Health facilities available to workers on most farms are extremely limited, particularly in the light of statutory requirements for occupational safety and health under the Machinery and Occupational Safety Act. It is argued that collective solutions to problems of pesticide safety are possible within the ambit of a public health response, particularly given the willingness of the farming community to identify and address potential health problems. As a result, initiatives to meet these needs are currently under way in the region.

Accidents, Occupational↗
PubMed1993

The Ray Alexander Workers Clinic--a model for worker-based health services in South Africa?

During the period of current political transition, concern for the future of South Africa's health services have led to increased interest in different models for the provision and financing of health care. These debates have included an examination of the concept of Managed Care and the ideas of Health Maintainance Organization. Progressive trade unions, particularly, have been faced with the prospect of promoting private sector health care if they are directly to meet their members health needs, while at the same time seeking an equitable health care system for a future democratic South Africa. The Ray Alexander Workers Clinic is presented as a model of a worker-based health service which attempts to address this contradiction. Important lessons for a future National Health Service may be learnt. The role of worker control and cost containment are emphasized and implications for integration into State Services and relationships to social services for the broader community are explored. An argument is made that worker-based health services offer excellent possibilities for integration in a future National Health Service in South Africa that is centred on a Primary Health Care approach.

Ambulatory Care Facilities↗