Search PubMedSearch

Biomedical subjects

J E Myers

Publications and source records attributed to J E Myers.

At least 19 recordsLinked to original sources

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

Influences on sick building syndrome symptoms in three buildings.

Relationships between symptoms typical of sick building syndrome, musculoskeletal symptoms, and reported indoor environmental exposures, psychological state, work stress and interpersonal relationships at work, were investigated among 624 office workers in three buildings. Symptom prevalences were similar in the three buildings, and were slightly lower in the two buildings characterized by its inhabitants as 'sick' than in the one building not considered to be 'sick'. Women were more likely than were men to complain of most symptoms in all three buildings. Multiple regression showed psychological symptoms and sex to be significant independent predictors of symptoms. Reported odours, and uncomfortable humidity and temperature were also independently associated with symptoms. The study indicates that sex and psychological symptoms are important predictors of perceived building related illness.

Adult

Sick building symptoms in office workers: a follow-up study before and one year after changing buildings.

Influences of physical and psychosocial work environments and personal factors on sick building syndrome symptoms were investigated in 167 clerical workers before and one year after moving from a naturally ventilated building to an artificially ventilated building. Female gender and work on visual display units were independently associated with most symptoms in the baseline survey and with the incident (new) symptoms in the follow-up survey. After changing buildings, the prevalences of eye, skin and fatigue symptoms increased significantly. Cold and discomfort due to stuffiness were independently associated with incident eye and respiratory symptoms. Reported domestic workloads were greater for women, but did not account for any gender differences in symptom prevalence.

Air Pollution, Indoor

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

Conceptualising health services in terms of level and location of care--a view from the academic health complex.

The origin and characteristics of academic health complexes (AHCs) are briefly outlined, along with pressures for restructuring of health services towards primary levels of care within the primary health care (PHC) approach. Weaknesses and strengths of the AHCs together with imbalances in the overall health system of which they are part are discussed. The Cape Town AHC is used to exemplify a suggested framework for analysis and development of other AHCs in South Africa and their transformation in accordance with the PHC approach. A method of service mapping is employed to aid an appreciation of the complexity of AHC services. Planning for potential transformation may be facilitated by conceptualising services in two dimensions, viz. level and location of care. Two important additional dimensions of service component linkage are integration across levels of care along a vertical axis, and integration across different services at primary level along a horizontal axis (comprehensiveness). AHCs, however skewly developed in terms of level and location of care, are complex combinations of services. They encompass all levels of care provided both within and beyond the walls of multiple health care facilities which are located both centrally and peripherally. AHC services are managed by health professionals in specific academic disciplines. They include PHC functions at the interface between primary and specialist care provision, and community health functions which are principally located outside the health care facilities in the community.(ABSTRACT TRUNCATED AT 250 WORDS)

Academic Medical Centers

Abnormal behavioral responses to fenfluramine in patients with affective and personality disorders. Correlation with increased serotonergic responsivity.

Serotonergic responsivity was assessed in 20 psychiatric patients by the prolactin response to a fenfluramine challenge test. During the fenfluramine challenge 6 of 20 patients (30%) spontaneously reported psychopathologic reactions that included: increased anxiety/agitation, psychotic symptoms, illusions, mood elevation, and anergia. The time of peak behavioral symptoms (2.5 +/- 0.8 hrs) corresponded closely to the time of peak increase in prolactin levels (3.0 +/- 1.1 hr). Abnormal behavioral responders had statistically significant greater increases in prolactin 1 to 4 hr after fenfluramine when compared to normal responders. Patients who developed an abnormal psychopathologic response to fenfluramine were characterized by higher levels of anxiety and agitation at the time of admission to the hospital but otherwise were not distinguishable on the basis of severity of other psychiatric symptoms. This study suggests that increased serotonergic transmission may trigger anxiety, psychosis, and mood elevation in specific vulnerable individuals, whereas other patients with similar psychiatric illnesses are not affected.

Adult

Application of two secondary documentary sources to identify the underreporting of fatal occupational injuries in Cape Town, South Africa.

We reviewed 8,502 deaths registered at the Salt River state mortuary, Cape Town (medical examiner records) for an 18-month period (1/1/90-6/30/91). When fatal occupational injuries located from this data source were matched with the records of the occupational safety inspectorate of the Department of Manpower, it was found that 28% had not been reported in terms of statutory regulations. Unreported deaths accounted for 25% of all fatal occupational injuries in the construction industry. None of the fatal occupational injuries in agriculture and fishing had been reported. Falls constituted 45% of the unreported fatalities. High levels of unreported fatal occupational injury indicate deficiencies in current occupational safety surveillance and enforcement in South Africa.

Accidents, Occupational

Development of observational methods for estimation of exposure to workplace postural stress.

Several recent studies have illustrated the need for a simple observational instrument for the estimation of exposure to postural stress in epidemiological studies of musculoskeletal disorders. Such an instrument is particularly necessary in developing countries. This paper describes the development of an observational instrument across a spectrum of industrial occupations in South Africa. The instrument was derived from adaptations to previously published observational methods and was specifically adapted to the measurement and application constraints identified during empirical development work in various industries. The final instrument fulfilled its aims of being applicable across a broad spectrum of jobs, including a broad spectrum of exposure variables and being reasonably cost- and time-effective. Some construct validity is indicated by the fact that two out of the three main exposure variables of interest showed significant associations with neck and shoulder pain in an epidemiological analysis. These variables were the score of summed estimates of the duration of time in sustained postures in a working day and the score of estimated overall repetitiveness based on cycle-time criteria. Further investigations are needed for pain at other anatomical sites. The measurement and scoring problems identified are discussed with reference to some aspects of these results.

Biomechanical Phenomena

Continuous ambulatory peritoneal dialysis: an option in the developing world?

OBJECTIVE: To evaluate specified biomedical, socio-economic, and psychosocial criteria as predictors of therapeutic success to optimize patient selection for continuous ambulatory peritoneal dialysis (CAPD) in a developing country. DESIGN: A retrospective cohort study investigating the relationship between episodes of peritonitis and exitsite infection, and predetermined biomedical, socioeconomic, and psychosocial data. SETTING: A CAPD unit in a large tertiary care teaching hospital. PATIENTS: All 132 patients entering the CAPD program between 1987 and 1991. RESULTS: Overall mean survival time on CAPD was 17.3 months. Peritonitis rates were high, especially among blacks. Multivariate analysis demonstrated that increased peritonitis rates were associated with age, black race, diabetes, and strongly so with several psychosocial factors. Because being black was strongly linked to poor socioeconomic conditions, repeat analysis excluding blacks showed the same associations with the above variables, but, additionally, several socioeconomic factors were associated with high peritonitis rates. No significant explanatory variables were shown for exit-site infections. CONCLUSIONS: The association of biomedical, socioeconomic, and psychosocial variables with high peritonitis rates has important implications for the selection of patients for CAPD in this setting.

Adult

The effects of fenfluramine on sleep and prolactin in depressed inpatients: a comparison of potential indices of brain serotonergic responsivity.

The effects of fenfluramine, an indirect serotonergic agonist, on electroencephalographic sleep and prolactin secretion were assessed in 12 unmedicated inpatients with a primary diagnosis of major depressive episode. Compared to prefenfluramine profiles, sleep studies performed following fenfluramine administration showed a statistically significant reduction of slow-wave sleep (SWS) (p < 0.001) and a corresponding increase in percentage of stage-2 sleep (p < 0.007). Automated delta wave counts per min decreased significantly during the first nonrapid eye movement (NREM) period (p = 0.04), and automated rapid-eye movement (REM) counts were also decreased in the second REM period (p = 0.02). These effects on sleep electroencephalogram (EEG) did not correlate significantly with another measure of serotonergic responsivity, namely peak prolactin level following fenfluramine, nor with the severity of depression. The reductions in SWS and REM counts are proposed to be the result of time-dependent changes in serotonergic neurotransmission following the administration of fenfluramine. These findings are consistent with earlier work suggesting a role for serotonin in initiation and regulation of SWS and REM sleep.

Adult

Antagonism of cocaine self-administration by the preferential dopamine autoreceptor antagonist, (+)-AJ 76.

(+)-AJ 76 is a presumed preferential dopamine (DA) autoreceptor antagonist which, in previous behavioral investigations, has displayed properties characteristic of both DA agonists and DA antagonists. In an attempt to test the hypothesis that (+)-AJ 76 might be an effective cocaine pharmacotherapy, the present experiments evaluated (+)-AJ 76's behavioral profile in 3 standard reinforcement paradigms. In the first experiment, (+)-AJ 76 paralleled a DA antagonist in that it failed to support self-administration behavior at all doses (0.1, 0.32, and 1.0 mg/kg/inj) tested. In the second experiment, (+)-AJ 76 (0.9, 3.5, and 14.0 mg/kg) closely resembled the DA agonist D-amphetamine (0.25, 1.0, and 4.0 mg/kg) in producing a clear dose-dependent conditioned place preference. In the third experiment, (+)-AJ 76 (1.88, 3.75, 7.5, 15.0, and 30.0 mg/kg) significantly reduced breaking points (BPs), increased rates of responding, and delayed the onset of responding for cocaine. While (+)-AJ 76 mimics a typical DA antagonist in its ability to reduce BPs and augment rates of responding for cocaine, recent evidence suggests that it more closely resembles a DA agonist in its ability to delay the onset of responding for cocaine. In summary, the present investigations have shown that (+)-AJ 76's profile in 3 reinforcement paradigms is unusual and not exclusively representative of either DA agonists or DA antagonists. The potential utility for such an agent in treating cocaine abuse is discussed.

Animals

n-hexane neurotoxicity in metal can manufacturing workers.

The relationship between n-hexane exposure and neurological symptoms and signs, and sensitivity to peripheral vibration, was investigated in 126 metal can manufacturing workers. Exposed workers were significantly more likely than unexposed workers to report at least one neurological symptom of the limbs. Highly exposed workers were able to detect tuning fork vibration for significantly shorter periods than unexposed workers, independent of the effects of age, height, sex, alcohol, and education. A tuning fork was more capable than the Vibratron of detecting neurotoxic effects of n-hexane.

Adult

Fenfluramine challenge test as a predictor of outcome in major depression.

It has been reported that low pretreatment cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) levels may correlate with better clinical response to selective serotonin reuptake inhibitors (SSRI) compared to non-serotonergic antidepressant drugs. We examined the hypothesis that serotonergic system status, as measured by the prolactin (PRL) response to fenfluramine (FEN), may predict outcome in a heterogenous sample treated with various types of antidepressant treatment. Higher PRL response predicted a favorable outcome for males and females treated with either pharmacotherapy, psychotherapy [milieu therapy with or without cognitive behavior therapy (CBT)], or electroconvulsive therapy (ECT). All patients in the high PRL response group responded to antidepressant therapies. Patients receiving ECT had the highest proportion of treatment responders, the highest degree of treatment response, and, unlike drug or psychotherapy treatment, improved significantly whether in the high or low PRL response group. PRL response to a single dose fenfluramine challenge may be a useful predictor of response to pharmacological or psychotherapeutic treatments in major depression. By contrast, ECT is an effective short-term treatment independent of pretreatment serotonergic responsivity.

Adolescent

Occupational and environmental epidemiology--similarities and contrasts.

There has been considerable growth in the disciplines of occupational and environmental epidemiology in recent years, with both fields having to deal with increasingly complex exposure profiles and adverse health outcomes. Environmental and occupational epidemiology as distinct from general epidemiology are compared and contrasted. Similarities and differences between the two fields are systematically discussed in terms of epidemiological peculiarities, study design characteristics, sampling procedures, exposure assessment, typical biases, problems in determining causation, ethical constraints, and implementation possibilities for research findings. There is a need in South Africa to provide adequate training to health professionals working in these fields, so that high-quality research, which has the potential to contribute significantly to improvements in the health of workers and the general public, can be undertaken.

Environmental Exposure