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Biomedical subjects

S Bennett

Publications and source records attributed to S Bennett.

At least 109 records · Page 6Linked to original sources
PubMed1995

Efficacy trial of malaria vaccine SPf66 in Gambian infants.

SPf66 malaria vaccine is a synthetic protein with aminoacid sequences derived from pre-erythrocytic and asexual blood-stage proteins of Plasmodium falciparum. SPf66 was found to have a 31% protective efficacy in an area of intensive malaria transmission in Tanzanian children, 1-5 years old. We report a randomised, double-blind, placebo-controlled trial of SPf66 against clinical P falciparum malaria in Gambian infants. 630 children, aged 6-11 months at time of the first dose, received three doses of SPf66 or injected polio vaccine (IPV). Morbidity was monitored during the following rainy season by means of active and passive case detection. Cross-sectional surveys were carried out at the beginning and at the end of the rainy season. An episode of clinical malaria was defined as fever (> or = 37.5 degrees C) and a parasite density of 6000/microL or more. Analysis of efficacy was done on 547 children (316 SPf66/231 IPV). No differences in mortality or in health centre admissions were found between the two groups of children. 347 clinical episodes of malaria were detected during the three and a half months of surveillance. SPf66 vaccine was associated with a protective efficacy against the first or only clinical episode of 8% (95% CI -18 to 29, p = 0.50) and against the overall incidence of clinical episodes of malaria of 3% (95% CI -24 to 24, p = 0.81). No significant differences in parasite rates or in any other index of malaria were found between the two groups of children. The findings of this study differ from previous reports on SPf66 efficacy from South America and from Tanzania. In The Gambia, protection against clinical attacks of malaria during the rainy season after immunisation in children 6-11 months old at time of the first dose was not achieved.

Animals↗
PubMed1995

Mortality and morbidity from malaria in Gambian children after introduction of an impregnated bednet programme.

After the success of a controlled trial of insecticide-treated bednets in lowering child mortality, The Gambia initiated a National Insecticide Impregnated Bednet Programme (NIBP) in 1992 with the objective of introducing this form of malaria control into all large villages in The Gambia. Five areas (population 115,895) were chosen as sentinel sites for evaluation of the NIBP. During the first year of intervention a 25% reduction was achieved in all-cause mortality in children 1-9 years old living in treated villages (rate ratio 0.75 [95% CI 0.57-0.98], p = 0.04). If one area where the programme was ineffective was excluded, the reduction was 38% (0.62 [0.46-0.83), p = 0.001). A decrease in rates of parasitaemia and high-density parasitaemia, an increase in mean packed-cell volume (rate ratio 0.75 [95% CI 0.59-0.98], p = 0.04) and an improvement in the nutritional status of children living in treated villages were also detected. In a country such as The Gambia, where nets were widely used and which has a good primary health care system, it is possible to achieve insecticide-treatment of bednets at a national level with a significant reduction in child mortality; but at a cost which the country cannot afford.

Bedding and Linens↗
PubMed1995

Priorities in global measles control: report of an outbreak in N'Djamena, Chad.

In N'Djamena, capital of Chad, measles vaccination coverage of 12-23-month-old children fell from 61% in 1990 to 15% in 1993. A community survey of measles after an outbreak in 1993 showed that among children < 5 years of age, the mean monthly attack rate was 37 per 1,000 (95% CI, 32-43) and the mean case fatality rate was 7.4%. Measles incidence was highest (77/1,000/month) in children aged 9-11 months and fell among children > 3 years of age. Incidence rates were high (56/1,000/month) among 6-8-month-old children, but only 3 deaths occurred in this age group. Measles vaccine efficacy, estimated by comparing attack rates in unvaccinated and vaccinated children, was 71% (95% CI, 59-80%). Extrapolation of the results to the city population indicated that an estimated 19,000 cases and > 1,000 measles-associated deaths occurred in 1993. This preventable morbidity and mortality, in a city where coverage was formerly among the highest in Africa, shows the need for sustained global commitment to preventive health care.

Age Distribution↗
PubMed1995

Entomological evaluation of the Gambia's National Impregnated Bednet Programme.

Entomological studies were conducted in paired study villages in three of the five study areas used for the epidemiological assessment of the Gambia's National Impregnated Bednet Programme. Baseline data collected in 1991 were compared with post-intervention data from 1992, when one of each village pair (from areas II, III and V) was included in the treatment programme in which villagers' nets were dipped in permethrin. In a longitudinal study, indoor-resting densities of Anopheles gambiae s.l. in the treated villages were significantly reduced, when compared with their paired untreated village, in areas II (t = 3.32, 13 degrees of freedom, P = 0.006) and III (t = 3.71, 13 degrees of freedom, P = 0.003). However, this was not associated with higher outdoor-biting rates in the evenings in the treated villages than in the controls. The reduction in vector population was most evident in area II, where the treated village was relatively isolated and 74% of the population slept under a treated net. Anopheles gambiae s.l. were also collected during two fortnightly periods in area V, where the sporozoite rates in 1991 had been relatively high (7.65% and 6.07%). There was no significant decrease in the sporozoite rate in the treated village in area V in 1992, despite the fact that this village was over 5 km from its nearest neighbouring village. However, the proportion of villagers sleeping under a treated net in this village was < 50%. No clear evidence for an epidemiologically significant 'mass killing effect', resulting from the village-wide use of treated nets, emerges in this or any other study undertaken in The Gambia. However, such an effect is indicated by results from Salikene, where the village mosquito population was relatively isolated and where the majority of the population slept under a treated net. This situation is unlikely to be repeated in most Gambian villages in the primary-health-care scheme, since treated and untreated villages are generally interspersed and the mosquito populations move freely between them. We must therefore conclude that, on a national scale, the nets provide an exceptionally high level of personal rather than community protection. The mechanisms underlying the personal protection are, however, still unclear.

Animals↗
PubMed1995

The manipulation of vision during the powerlift squat: exploring the boundaries of the specificity of learning hypothesis.

The available information for controlling a multidegree-of-freedom sport action was manipulated in 2 experiments. In the first, 10 intermediate lifters were participants; for the second, 8 skilled and 8 less skilled lifters were observed. Three single repetitions of a powerlift squat were performed under 3 vision conditions (i.e., full, ambient, no vision). The less skilled and intermediate lifters' technical performance decreased significantly with the removal of visual information. There was no detrimental effect in the skilled group. Despite the differing information constraints, skilled lifters exhibited a high level of positioning accuracy and timing consistency across conditions. These data fail to support the theoretical predictions of the specificity of learning hypothesis. The differences between the task constraints in this study and those in manual aiming investigations may represent a boundary to the current propositions of the specificity of learning hypothesis.

Adult↗
PubMed1995

Genetic regulation of fever in Plasmodium falciparum malaria in Gambian twin children.

The role of genetic factors in determining the clinical response of children to Plasmodium falciparum infection is not fully understood. A longitudinal survey of malaria morbidity in a cohort of 258 pairs of twin children was conducted in a rural area of Gambia to assess the extent to which genetic factors determine the host's susceptibility and clinical response to infection. The marginal correlation (which measures the excess probability of both twins being affected above that expected assuming independence) for malaria was higher in dizygous (DZ) than in monozygous (MZ) twin pairs, indicating that infection per se is largely determined by environmental factors. Once infected however, both members of an MZ pair were more likely to develop fever than were twins of a DZ pair, suggesting that genetic factors influence the presentation of clinical disease.

Child↗
PubMed1995

Evidence against a potential endoplasmic reticulum transmembrane domain of 27K zein expressed in Xenopus oocytes.

During the cellular protein targeting process, zeins (maize storage proteins) are retained in the endoplasmic reticulum (ER) where they accumulate into protein bodies. There are circumstantial and preliminary data indicating that the 27K zein, a class of zein proteins, may span the ER membrane. This potential transmembrane domain is considered very significant with regard to the mechanism of ER retention for zeins. The potential transmembrane domain may permit the 27K zein to remain in the ER and to serve as an anchor for other classes of zein, thus acting as a nucleating factor for protein body formation. This study investigated the potential transmembrane feature in a heterologous system (Xenopus laevis oocyte). Following injection of synthetic 27K zein mRNA, isolated protein vesicles were subjected to proteinase K digestion, surface biotinylation and alkaline extraction. Throughout three categories of assay the possible role of the 27K zein as a transmembrane protein was consistently refuted in this study. The 27K zein polypeptide was affected by neither proteinase K digestion nor biotinylation and was released from alkali-stripped membranes. This study, therefore, concludes that the 27K zein is not a protein body nucleating factor by virtue of an ER transmembrane feature.

Animals↗
PubMed1995

A pilot safety and immunogenicity study of the malaria vaccine SPf66 in Gambian infants.

A pilot safety and immunogenicity trial of the malaria vaccine SPf66 has been undertaken in 150 Gambian infants. No significant systemic side effects were recorded but modest local reactions were seen after the administration of a third 1.0 mg dose. SPf66 produced in Colombia was more immunogenic than SPf66 produced in the USA and a 1.0 mg dose of each vaccine gave higher antibody levels than a 0.5 mg dose. However, antibody levels fell rapidly after administration of the third dose of vaccine and showed little change over the following malaria transmission season. The incidence of clinical malaria was higher among children who received SPf66 than among children who received inactivated polio vaccine, the effect being most marked among children who received 1.0 mg Colombian SPf66. As the trial was not designed to measure the effect of SPf66 on morbidity from malaria, the significance of this finding is uncertain.

Animals↗
PubMed1995

Cardiovascular risk factors in Australia: trends in socioeconomic inequalities.

STUDY OBJECTIVE: To examine trends in socioeconomic inequalities in cardiovascular risk factors using educational attainment to indicate socioeconomic status. DESIGN: Behavioural data, physical measurements, blood pressure, and lipid determination collected in three, successive multicentre cross sectional community surveys conducted in 1980, 1983, and 1989. SETTING: The six state capital cities of Australia; Sydney, Melbourne, Brisbane, Adelaide, Perth, and Hobart. PARTICIPANTS: A total of 19,315 randomly selected respondents stratified by age (25-44, 45-64) and sex. RESULTS: During the 1980s, average blood pressure declined for each level of educational attainment. Dietary messages to reduce the intake of saturated fat had little effect on the lipid profile of any population group. Height and educational attainment were positively associated. Women increased in weight from between 2 to 4 kg depending on age and educational attainment while older men experienced increases of around 2.5 kg regardless of educational attainment. Advice to avoid salt was adopted across the spectrum of educational attainment but with no suggestion that the socioeconomic gradient, which favoured the more highly educated, was diminishing. Men of all education levels responded positively to the anti-smoking initiatives of the 1980s but the relative disadvantage of those of lower education was maintained. Among women, the decline in smoking was less among those in the low education group. The prevalence of moderate to heavy drinkers was higher in men of lower educational attainment but declined significantly over the period. Walking for recreation or exercise became more popular, especially among older men of low education, while the prevalence of aerobic exercise and vigorous exercise remained largely unchanged. Overall, the clear socioeconomic gradient between leisure time physical activity and education attainment remained. CONCLUSIONS: The lower socioeconomic group has improved its risk factor profile but its relative disadvantage compared with the higher socioeconomic group persists. Health promotion activities in Australia seem to have been effective in reaching the lower socioeconomic groups but the challenge to reduce inequalities remains. The steady increase in educational attainment in Australia may have been an important factor in the general improvement in the nation's risk factor profile and in the decrease in mortality from coronary heart disease.

Adult↗
PubMed1994

Variables in the isolation and culture of human monocytes that are of particular relevance to studies of HIV.

Mononuclear phagocytes play an important role in human immunodeficiency virus (HIV) infection. However, knowledge of the extent of macrophage involvement in the pathogenesis of HIV infection is still incomplete. This is due in part to the technical difficulties associated with isolating, purifying, and culturing these cells. Isolation of a pure population of human monocytes is essential when studying the role of these cells in HIV infection. In addition, the differentiation, activation, and replication of human monocytes are critically affected by both isolation and culture conditions. This review examines the different monocyte isolation and purification methods and culture conditions that are currently being employed and assesses their suitability for studying the functions of monocytes in HIV infection.

Cell Separation↗
PubMed1994

Blood pressure measurement error: its effect on cross-sectional and trend analyses.

The measurement of blood pressure in epidemiological studies is difficult to standardize between centres in multi-centre studies and between repeat surveys over time. The use of standard mercury sphygmomanometers is common but especially prone to measurement error in terms of departure from the protocol and variation in measurement technique. Data from Australia's cardiovascular risk factor prevalence surveys on 21 independent populations, distributed geographically and temporally, has been examined to assess the effect of these errors on cross-sectional and trend analyses. The examination showed that last digit preference for zero may inflate estimates of proportions having high blood pressure. A tendency to record identical duplicate measurements could contribute 0.85 mmHg to time trends or geographic differences in mean systolic blood pressure (but not diastolic blood pressure). Epidemiological studies for geographic and trend differentials in systolic blood pressure need to be mindful of these effects in their analysis. There was some evidence of deterioration in data quality during data collection but no evidence that observers were influenced in their recording practice by observable respondents' characteristics. Training procedures for blood pressure measurement are of critical importance and adherence to the measurement protocol should be continuously monitored during data collection to ensure comparability of results.

Adult↗