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Biomedical subjects

D Rees

Publications and source records attributed to D Rees.

At least 55 records · Page 3Linked to original sources
PubMed1996

A guide to spirometry as applied to occupational health.

In the context of occupational health, spirometric testing of respiratory function has a number of important applications. These applications can be expected to become more widespread in view of extensive changes to occupational health and compensation legislation in South Africa. Spirometry is an essential component of pre-assignment medical examinations at the commencement of employment; of medical surveillance of workers exposed to hazardous substances so as to intervene when early changes in pulmonary function are detected; of medical evaluation of functional impairment for appropriate job relocation or compensation; and of research. These applications of spirometry each have special considerations which are detailed.

Female↗
PubMed1995

Platinum salt sensitivity in refinery workers: incidence and effects of smoking and exposure.

OBJECTIVE: To measure the incidence of platinum salt sensitivity (PSS) in refinery workers and examine the influence of cigarette smoking and exposure to platinum salts on sensitisation. DESIGN: A prospective cohort study with examination of workers at quarterly intervals for 18 months, and again at 24 months. SETTING: A South African primary platinum refinery. SUBJECTS: 78 new recruits, selected by the refinery's usual procedure, without apparent atopy and in good respiratory health. RESULTS: After 24 months 32 (41%) subjects had been diagnosed PSS and were subsequently medically separated. Twenty two (28%) cases were confirmed by positive skin prick test to platinum salts, 10 (13%) cases were symptomatic but skin prick negative. Incidence of cases per 100 person-months was 1.9 skin prick positive and 0.8 negative. Risk of sensitisation was about eight times greater for smokers than non-smokers, and six times greater for high exposure than low exposure. CONCLUSION: Smoking and intensity of exposure were definitely associated with development of PSS. Positive responses to platinum salt skin prick test had a 100% positive predictive value for symptoms and signs of PSS if exposure continued.

Asthma↗
PubMed1995

Tests for sensitisation in occupational medicine practice--the soy bean example.

OBJECTIVE: To determine the prevalence of sensitisation to soy bean measured by specific IgE and skin prick tests (SPTs) and to examine the association between evidence of sensitisation to soy bean allergens and symptoms of allergic disease. DESIGN: Cross-sectional study. Questionnaire survey. A venous blood sample was taken for specific IgE testing, and SPTs for common allergens and soy bean dust were performed. SETTING: Soy bean mill. PARTICIPANTS: A volunteer sample of 22 workers exposed to soy bean dust; the first 20 non-exposed workers presenting to the National Centre for Occupational Health clinic formed the control group. MAIN OUTCOME MEASURE: Immunological tests for sensitisation and symptoms of respiratory and allergic disease. RESULTS: Eight of the exposed workers had positive skin reactions to either full-fat or defatted soy bean. None of the controls was SPT-positive. Eight of the exposed workers had increased levels of soy-specific IgE of whom only 4 were SPT-positive and had an increased level of soy-specific IgE. One of the control workers had an increased level of soy-specific IgE. Workers with an increased specific IgE or SPT positive to soy bean did not have more symptoms than workers with negative tests. However, work-related breathlessness was significantly higher in the exposed group (P < 0.05). CONCLUSIONS: The data suggest that the immunological tests for sensitisation were not useful in identifying workers with soy bean-related disease but that tests for sensitisation were linked to exposure.

Bronchial Provocation Tests↗
PubMed1994

In vitro proguanil activation to cycloguanil by human liver microsomes is mediated by CYP3A isoforms as well as by S-mephenytoin hydroxylase.

1. The activation of proguanil to cycloguanil by human liver microsomes was studied to define the cytochrome P450 (CYP) isoforms involved in this reaction. 2. Apparent Km values for proguanil ranged from 35 microM to 183 microM with microsomes from four human livers. 3. There was a 6.3-fold range of activity with microsomes from seventeen human livers. Rates of proguanil activation correlated significantly with CYP3A activities (benzo[a]pyrene metabolism, caffeine 8-oxidation and omeprazole sulphone formation) and CYP3A immunoreactive content. There was also a highly significant correlation with rates of hydroxyomeprazole formation. Correlations with activities selective for CYP1A2, CYP2C9/10 and CYP2E1, and with immunoreactive CYP1A2 content were not significant. 4. Proguanil activation was inhibited by R,S-mephenytoin, troleandomycin and by inhibitory anti-CYP3A antiserum and anti-CYP2C IgG and was activated by alpha-naphthoflavone. Inhibitors selective for CYP1A2, CYP2E1, CYP2A6 or CYP2C9/10 had little or no effect on proguanil activation. The extents of inhibition by R,S-mephenytoin, troleandomycin and the two antibodies varied with the immunoreactive CYP3A content of the microsomes used. 5. It is concluded that proguanil activation to cycloguanil by human liver microsomes is mediated both by S-mephenytoin hydroxylase and isoforms of the CYP3A subfamily. This has implications for the use of proguanil as an in vivo probe for the S-mephenytoin poor metaboliser phenotype.

Aryl Hydrocarbon Hydroxylases↗
PubMed1994

Use of splenic ultrasound: a new wave for immune thrombocytopenic purpura.

AIMS: To examine whether a therapeutic dose of ultrasound waves, when directed through the thoracic wall to the spleen, would significantly affect the platelet count in patients with stable immune thrombocytopenic purpura (ITP). METHODS: Continuous ultrasound at 1 W/cm2 spatial average-time average (SATA) intensity for up to one minute/5 cm2 treatment field was well tolerated in 13 patients with ITP and one with non-Hodgkin's lymphoma. Five healthy controls were also similarly treated. Peak platelet increments occurred four to eight hours after ultrasound treatment in the ITP group (n = 16 treatments). RESULTS: The mean peak platelet increment was 6.25 x 10(9)/l with a 5% confidence interval of the mean (95% CI) of 3.32 to 8.93 x 10(9)/l (p = 0.0004). The mean peak platelet increment of normal controls was 6.6 (n = 5; 95% CI = -2.3 to 15.5; p = 0.21) and for sham treated patients it was 0.66 (n = 11; 95% CI = -1.5 to 2.8; p = 0.60). There was a significant inverse correlation between patient age in the ITP group and peak platelet increment (r = -0.60; p = 0.015). CONCLUSIONS: Splenic ultrasound is a novel approach to the treatment of ITP, and may find a place in its diagnosis or management.

Adult↗
PubMed1994

Differential induction of nitric oxide synthase in various organs of the mouse during endotoxaemia: role of TNF-alpha and IL-1-beta.

BALB/c mice injected intraperitoneally with bacterial lipopolysaccharide (LPS) developed lethal septic shock. This was accompanied by significantly elevated concentrations of nitrite and nitrate in the plasma and expression of high levels of nitric oxide (NO) synthase activity in the lungs, heart, spleen and peritoneal macrophages. Mice pretreated with anti-tumour necrosis factor-alpha (TNF-alpha) monoclonal antibody or anti-interleukin-1 beta (IL-1 beta) polyclonal antibody were protected, in a dose-dependent manner, from endotoxin-induced mortality. This effect was accompanied by a significant reduction in plasma levels of nitrite and nitrate. Antibody treatment also reduced the level of NO synthase activity in peritoneal macrophages, spleen and heart but had no effect on enzyme expression in the lung. These results demonstrate that TNF-alpha and IL-1 beta play an important role in the induction of NO following administration of LPS and in the development of endotoxin-induced shock. In addition, NO synthase activity is differentially expressed in various organs and this may not always require TNF-alpha and IL-1 beta.

Amino Acid Oxidoreductases↗
PubMed1994

Dust and pneumoconiosis in the South African foundry industry.

The objectives of this study were to estimate the extent of occupational health monitoring for dust and pneumoconiosis in the foundry industry and to assess dust levels and the prevalence of pneumoconiosis in a group of foundries. In only 13 (16%) of the 82 foundries that responded to a postal questionnaire were regular periodic full-sized chest radiographs done. Dust levels were measured every 3 years or more frequently in 20 foundries (24%). An uncontrolled dust hazard was evident in all 9 foundries surveyed between 1983 and 1992. The prevalence of silicosis ranged from 0% to 10.3% and increased with duration of service. The study provided convincing evidence of neglect of occupational health by the foundry industry.

Dust↗
PubMed1994

Third wave of asbestos-related disease from secondary use of asbestos. A case report from industry.

An occupational health survey conducted in a workshop in which asbestos cement was used showed initial atmospheric asbestos levels ranging from 1.9 to 27.5 fibres per millilitre of air. Radiological changes suggestive of asbestos-related pleural disease were found in 2 workers (2.5%), while 3 (3.8%) had borderline features of asbestosis. The survey confirmed that uncontrolled and hazardous use of asbestos continues in industry despite public awareness of its dangers and the Asbestos Regulations of 1987.

Asbestos↗
PubMed1994

Compensation for occupational lung disease in non-mining industry.

The course from claim submission (by the National Centre for Occupational health (NCOH)) to compensation (by the Workmen's Compensation Commissioner (WCC)) in 56 cases of occupational disease (OD) was traced. Success rates were determined and the procedural factors which affect claim outcomes isolated. Of note are the 22% of claims which remained unresolved 3 years after submission. The long latent period of ODs causes difficulty in obtaining the employer's corroborating documentation; this was found to be a major factor in the non-resolution of claims. Active intervention by the NCOH resulted in claim resolution for an additional 9%. These findings support the proposal that the WCC establish a network of access points for workers where assistance from trained staff is available. It is further recommended that the WCC accept substitutes for the employer's documentary proof in cases where this is unobtainable.

Adult↗
PubMed1993

A cross-sectional survey of neurobehavioral effects of chronic solvent exposure on workers in a paint manufacturing plant.

Neurobehavioral impairments in 84 workers with long-term exposure to organic solvents in a paint manufacturing plant were examined cross sectionally. The World Health Organization (WHO) Neurobehavioral Core Test Battery, the NES-2 computerized battery, and four additional South African tests were used. Exposure to solvents was determined by using company industrial hygiene data as well as from an industrial hygiene survey of current total solvent levels in air. Indexes for cumulative exposure and average lifetime intensity of exposure were calculated for groups of homogeneously exposed workers in each department. Exposure levels were below the AGGIH threshold limit values. Multiple linear regression revealed that education level, age, and alcohol consumption were strong predictors for several neurobehavioral test scores. After adjusting for potential confounding from this source, average lifetime intensity of solvent exposure was the most significant predictor of the NES-2 Continuous performance test (measuring sustained visual attention) score of the WHO Digit span backward test score (measuring attention span and double tracking). Pursuit aiming (measuring fine visuomotor tracking speed) was significantly associated with the cumulative exposure index, possibly indicating early neurotoxic effects.

Central Nervous System↗
PubMed1993

Neuropsychological assessment of organic solvent effects in South Africa: test selection, adaptation, scoring, and validation issues.

The neurobehavioral effects of organic solvent exposure were assessed in 68 South African workers in a paint manufacturing plant in which the maximum current combined solvent level in workplace air was 0.72 of the Threshold Limit Value. A 17-test battery was assembled from the WHO-NCTB, NES 2, and the University of South Africa Neuropsychological Assessment Procedure. Extensive modifications were made to some tests in the battery, using a guided learning rationale derived from the cross-cultural literature. In light of test correlations with demographic variables (age, education, and alcohol consumption), the construct and likely predictive validity of the tests in the battery are reviewed, and promising procedures identified. Finally, it is noted that in developing countries, the results of neuropsychological tests that have been well standardized in the West may be misleading unless the underlying validity issues that arise when a test developed in one culture is applied to another have been addressed.

Adult↗
PubMed1993

Research note: reliability of self-report sickness absence data in the health service.

Rees and Cooper (1990) used self-reports of sickness absence during the previous six months as a dependent measure in a diagnostic survey of stress in one health district. Comparison of self-reports with actual sickness absence showed that it achieved a high level of association (0.95) and can be recommended as an alternative to actual sickness data in studies in which, for whatever reason, actual sickness absence is difficult to obtain.

Absenteeism↗
PubMed1993

A functionally specialized alpha-tubulin is required for oocyte meiosis and cleavage mitoses in Drosophila.

Three alpha-tubulin proteins contribute to microtubules during oogenesis and early embryogenesis in Drosophila melanogaster: alpha TUB84B, alpha TUB84D, and alpha TUB67C. alpha TUB67C is unique in two respects. It is a structurally divergent alpha-tubulin, sharing only 67% amino acid identity with the generic isotypes alpha TUB84B and alpha TUB84D, and its expression is exclusively maternal. The genetic analysis of the alpha Tub67C gene described here demonstrates that alpha TUB67C is required for nuclear division in the oocyte and early embryo. Both meiosis and cleavage-stage mitoses are severely affected by mutations that result in a substantial decrease in the ratio of alpha TUB67C/alpha TUB84B+alpha TUB84D. A large increase in this ratio, achieved by increasing the gene dosage of alpha Tub67C, has little or no effect on meiosis, but severely disrupts mitotic spindle function. Thus, both classes of alpha-tubulin isotype present in the mature oocyte, alpha TUB67C and alpha TUB84B/84D, are essential for normal spindle function in early Drosophila development. These alpha-tubulins provide the first example of tubulin isotypes known to be coexpressed in wild-type animals whose encoded variation is required for the normal function of a microtubule array.

Animals↗