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Biomedical subjects

D Rees

Publications and source records attributed to D Rees.

At least 37 records · Page 2Linked to original sources
PubMed1999

Neuropsychological function in solvent-exposed South African paint makers.

Neuropsychological and neurological function were investigated in 228 organic solvent exposed paint manufacturing workers in two factories. Solvent exposure was expressed as both American Conference of Governmental Industrial Hygienists 1990 Threshold Limit Value equivalents and total hydrocarbon parts per million. The World Health Organization (WHO) neurobehavioral core test battery, the Neurobehavioural Evaluation System--2 (NES-2), and the UNISA Neuropsychological Assessment Procedure (UNAP) were used to measure outcomes, and a Vibratron II was used to measure peripheral vibration sensation. Exposures were generally below the Threshold Limit Value, and no exposure effect was found. Possible explanations for this finding are discussed, including low exposure, exposure, and outcome misclassification, together with inappropriateness, nonvalidity, and relative insensitivity of neuropsychological tests. Only age predicted Vibratron score. Some tests were clearly inappropriate for use in developing countries. Neuropsychological tests were sensitive to educational level, age, alcohol consumption, and cultural indicators. The WHO tests in particular showed good construct validity for neuropsychological functions and should be more formally validated for use in developing countries. Nevertheless, a major problem of cultural dependence is evident for all neuropsychological tests used in this study, and methods for bypassing this problem in less developed settings are discussed.

Adult↗
PubMed1999

Immunological development and cardiovascular function are normal in annexin VI null mutant mice.

Annexins are calcium-binding proteins of unknown function but which are implicated in important cellular processes, including anticoagulation, ion flux regulation, calcium homeostasis, and endocytosis. To gain insight into the function of annexin VI, we performed targeted disruption of its gene in mice. Matings between heterozygous mice produced offspring with a normal Mendelian pattern of inheritance, indicating that the loss of annexin VI did not interfere with viability in utero. Mice lacking annexin VI reached sexual maturity at the same age as their normal littermates, and both males and females were fertile. Because of interest in the role of annexin VI in cardiovascular function, we examined heart rate and blood pressure in knockout and wild-type mice and found these to be identical in the two groups. Similarly, the cardiovascular responses of both sets of mice to septic shock were indistinguishable. We also examined components of the immune system and found no differences in thymic, splenic, or bone marrow lymphocyte levels between knockout and wild-type mice. This is the first study of annexin knockout mice, and the lack of a clear phenotype has broad implications for current views of annexin function.

Animals↗
PubMed1999

Asbestos exposure and mesothelioma in South Africa.

OBJECTIVES: To describe the exposure experiences of South African mesothelioma cases, with emphasis on the contribution made to the caseload by different fibre types, the proportion of subjects with no recall of asbestos exposure and only environmental contact, and the importance of putative causes other than asbestos. DESIGN: A multi-centred case-control study. SUBJECTS AND SETTING: 123 patients with mesothelioma interviewed by trained interviewers in study centres established in Johannesburg, Kimberley, Pretoria, Bloemfontein, Cape Town and Port Elizabeth. RESULTS: A convincing history of asbestos exposure was obtained in the overwhelming majority of cases (only 5 cases had unlikely asbestos exposure). Twenty-three subjects had worked on Cape crocidolite mines, 3 at Penge (an amosite mine), 3 on mines producing amosite and Transvaal crocidolite and 1 on a Transvaal crocidolite mine. Exclusively environmental exposure accounted for at least 18% of cases; 91% of these cases (20/22 subjects) had had contact with Cape crocidolite. There was a relative paucity of cases linked to amosite and no convincing chrysotile case. Non-asbestos causes occur rarely, if at all, in South Africa. CONCLUSION: The preponderance of crocidolite cases, followed by amosite and then chrysotile cases, is consistent with the view that there is a fibre gradient of mesotheliomagenic potential for South African asbestos (crocidolite > amosite > chrysotile).

Asbestos, Amosite↗
PubMed1998

Intra-articular lipoma of the hip. A case report.

This report describes a rare intra-articular lipoma of the hip which developed in a 31-year-old male after a football injury. A plain X-ray and an MRI scan of the hip showed no bony abnormalities. After the patient failed to improve with a rehabilitation programme, arthroscopy of the hip was performed, revealing a lump in the acetabular fossa associated with a labral tear. A histopathological analysis confirmed the diagnosis of an intra-articular lipoma of the hip joint, which to our knowledge is the first reported case in the literature.

Adult↗
PubMed1998

Regression of extramedullary haemopoiesis and augmentation of fetal haemoglobin concentration during hydroxyurea therapy in beta thalassaemia.

Hydroxyurea increases fetal haemoglobin in many patients with sickle cell anaemia, but its effectiveness in thalassaemia appears to be less consistent. We describe the response to hydroxyurea in an adult male with homozygous beta thalassaemia, symptomatic paraspinal extramedullary haemopoiesis, bone pain, and progressive tissue iron loading. Prior to therapy with hydroxyurea the circulating haemoglobin (Hb) concentration was 7.0 g/dl and absolute fetal haemoglobin concentration was 5.0 g/dl. Administration of sodium phenylbutyrate had induced no increase in either parameter. Subsequent therapy with hydroxyurea was associated with increases in total haemoglobin to 9.0 g/dl, and in fetal haemoglobin to 7.6 g/dl. Ineffective erythropoiesis was reduced and extramedullary haemopoiesis regressed during therapy.

Adult↗
PubMed1998

Influence of acute endurance activity on leg neuromuscular and musculoskeletal performance.

PURPOSE: The purpose of this study was to investigate the effect of endurance activities designed to simulate the physiological demands of soccer match-play and training, on leg strength, electromechanical delay, and knee laxity. METHODS: Eight recreational soccer players completed four exercise trials in random order: 1) a prolonged intermittent high intensity shuttle run (PHISR) which required subjects to complete a total distance of 9600 m in a form simulating the pattern of physical activity in soccer match-play (activity mode; rest-to-work intervals; approximately 90 min duration), 2) a shuttle-run (SR), (3) a treadmill run (TR) which required subjects to complete an equivalent distance at a running speed corresponding to 70% VO2max, and 4) a control condition consisting of no exercise. RESULTS: Results from repeated measures ANOVA revealed significant condition (PHISR; SR; TR; control) by time (pre; mid; post) interactions for peak torque (PT: knee extension and flexion: 1.05 rad.s-1), EMD and anterior tibio-femoral displacement (TFD) (P < 0.05). Impairment to indices of knee joint performance was observed in PHISR, SR, and TR trials. The greatest decrement occurred in PHISR and SR trials (up to 44%). Knee extensor and flexor strength performance near to full knee extension (0.44 rad knee flexion) was not changed following the functionally-relevant endurance activities. CONCLUSIONS: Even though strength performance near to full knee extension was preserved following acute endurance activities, the risk of ligamentous injury may be increased by concomitant impairment to EMD and anterior TFD.

Adult↗
PubMed1998

Psychobiology and the athlete with anterior cruciate ligament (ACL) injury.

Over the past decade, research has increasingly highlighted the need for psychological aspects associated with sporting injury to be considered in treatment programmes. However, contemporary practice continues to focus on the treatment of the physical injury. The purpose of this article is to summarise research and contemporary thoughts on the psychological aspects associated with sporting injury. The potential for incorporating both physical and psychological aspects into the treatment of injury is discussed with special reference to the anterior cruciate ligament (ACL) injury. Specifically, the potential importance of athlete involvement throughout the treatment programme is discussed. Additionally, the physical and psychological measures that are available to the sports medicine team to measure rehabilitation outcome are critically evaluated. The limitations of psychological measures of the athlete's perception of outcome are outlined. Evidence for the utility of the performance profile technique is critically evaluated. The technique provides valid and reliable measures of the idiosyncratic responses of athletes to injury to provide a framework for effective treatment for optimised outcome.

Anterior Cruciate Ligament Injuries↗
PubMed1998

Respiratory health and immunological profile of poultry workers.

OBJECTIVES: To examine work-related respiratory symptoms in poultry workers, and to test for immunologically mediated responses to poultry-related agents. DESIGN: A cross-sectional survey of differentially exposed poultry workers and unexposed blue-collar workers. SETTING: Three poultry farms and a poultry plant in Gauteng (exposed workers) and a municipal workers' clinic in Johannesburg (controls). PARTICIPANTS: 134 poultry workers (85.4% of all eligible workers) and 122 controls (> 95% response rate). OUTCOME MEASURES: Respiratory symptoms plus allergy and hypersensitivity to poultry agents identified by skin-prick tests, and by the presence of specific IgE and IgG enzyme-linked immunoflow assay and nonspecific (radial immunodiffusion) antibodies. RESULTS: Smoking habits and atopic status were similar in the poultry workers and the controls. Symptoms were very common in poultry workers, for example work-related cough in 32% and work-related wheeze in 23% of highly exposed workers. Significantly more poultry workers than controls complained of chest symptoms (increasing with increasing exposure), and of eye, skin and nose irritation at work. More poultry workers than controls had symptoms consistent with asthma (e.g. 3%, 4%, 13% and 11% in controls and subjects with low, medium and high exposure, respectively), and symptom complexes associated with organic dust exposure. Five poultry workers had positive skin-prick test reactions to poultry-specific antigens, but none of the unexposed controls reacted. More poultry workers than controls had positive immunodiffusion test reactions to chicken feed, feathers and serum, and IgE to chicken faeces. There was no association between immunological status and respiratory symptoms. CONCLUSION: We found a very high prevalence of exposure-related symptoms in poultry workers; improved hazard control is strongly indicated. Tests of allergy and hypersensitivity were associated with exposure, but not with disease. The possibility of useful tests of sensitisation has not been excluded; a prospective study design is likely to be more rewarding than cross-sectional approaches such as in this study.

Air Pollutants, Occupational↗
PubMed1997

Influence of genetic predisposition to thrombosis on natural history of acute promyelocytic leukaemia. MRC Adult Leukaemia Working Party.

There is currently no means of identifying the subgroup of APL patients who will succumb to haemorrhagic or thrombotic complications. We have investigated factor V Leiden and thermolabile methylene tetrahydrofolate reductase (MTHFR) to determine whether these are of predictive value for thrombosis in the context of APL. Of 48 patients drawn from the MRC ATRA trial, two were heterozygous for factor V Leiden (allele frequency 2.1%). 10 homozygotes and 17 heterozygotes for thermolabile MTHFR were identified (allele frequency 38.5%). Amongst these patients, one thrombosis occurred (thermolabile MTHFR heterozygote). In the group with no identified increased thrombotic risk, three episodes were recorded. This approach failed to predict thrombotic events in APL, although the exact implications of specific genotypes remain to be established by larger studies.

Factor V↗
PubMed1997

Staff stress on the intensive care unit: a comparison of doctors and nurses.

Working on an intensive care unit is perceived as stressful. This study investigated occupational stress in staff working on an intensive care unit using the occupational stress indicator. Questionnaires were given to all intensive care staff; the replies were then analysed and compared with normative data. The response rate was 62%. Intensive care unit staff found aspects of their job relating to career and achievement and organisational design and structure more stressful than a normal working population. Their coping strategies differ but the only significantly different measure of adverse outcome was related to personal relationships at work. The job itself was not found to be a significant source of stress. Nursing staff have different sources of stress from medical staff and individuals with partners or children are relatively protected from stress.

Adaptation, Psychological↗
PubMed1996

Homocysteine modification of HLA antigens and its immunological consequences.

Homocysteine-treated cells can be specifically lysed by cytotoxic T lymphocytes (CTL) identifiable in patients with ankylosing spondylitis and reactive arthritis. Sensitization of target cells involves disulfide bonding and the interaction between homocysteine and HLA antigens occurs in a pre-Golgi compartment in the cells. Salmonella-infected B cells are also lysed by homocysteine-specific CTL, suggesting that intracellular invading microorganisms may provide homocysteine which would gain access to the newly synthesized intracellular HLA molecules and modify them inside the cells. Two different mechanisms for homocysteine modification of HLA antigens are proposed: homocysteine could bind directly to the unpaired cysteine residues in HLA antigens, or it could bind indirectly to HLA antigens through cysteine-containing peptides bound to them. Thus, HLA antigens containing unpaired cysteine residues (e.g. HLA B27) could be modified by homocysteine directly or indirectly, while HLA antigens without unpaired cysteine residues (e.g. HLA A68) could only be modified indirectly. The results are discussed in relation to the potential involvement of homocysteine-specific CTL in ankylosing spondylitis and reactive arthritis, both of which are related to bacterial infections, associated with HLA B27, and considered to be autoimmune diseases.

Adult↗
PubMed1996

Nitric oxide and the regulation of blood pressure in the hypertension-prone and hypertension-resistant Sabra rat.

We examined the role of nitric oxide (NO) in the inherited resistance or susceptibility to hypertension in the Sabra hypertension-prone (SBH) and hypertension-resistant (SBN) rat. Basal mean arterial blood pressure was significantly greater in SBH than in SBN rats. Phenylephrine elevated blood pressure to a similar extent in both substrains, whereas the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) had a greater pressor effect in SBN rats. The vasoconstrictor potency of phenylephrine was significantly higher in endothelium-intact aortic rings from the SBH rat, whereas the vasoconstrictor potency of L-NMMA was higher in those from the SBN substrain. Acetylcholine-induced endothelium-dependent relaxation was greater in aortic rings from SBN rats. The vasodilator potency of glyceryl trinitrate was significantly higher in aortic rings from SBH rats and was enhanced after endothelium removal. Both the activity of calcium-dependent NO synthase from aortic endothelial cells and the basal concentration of nitrite/nitrate in plasma were significantly greater in SBN than in SBH rats. In normotensive Wistar rats, basal mean arterial blood pressure, the pressor effect of L-NMMA, endothelial NO synthase activity, and plasma nitrite/ nitrate concentrations were all between the values in SBH and SBN rats. These results indicate that a decrease in NO generation plays a role in the susceptibility of SBH rats to hypertension. Furthermore, the resistance to hypertension in the SBN strain may be related to increased NO generation.

Animals↗
PubMed1996

Occupational health nurses and occupational hygiene: a study of South African nurses' attitudes.

The objectives of this study were to assess the current occupational hygiene practices of occupational health nurses and to assess their attitudes to the identification and initial quantification of workplace hazards. A questionnaire was mailed to all occupational health nurses registered with the South African Society of Occupational Health Nurses. Responses were obtained from 221 (53.7%). Responders and non-responders did not differ on key characteristics. Only 14 (6%) of the respondents performed occupational hygiene tasks as part of their routine work and only 31 (14%) volunteered hazard identification and quantification as tasks that would significantly improve practice. Nevertheless, when asked directly, 120 (54%) agreed that occupational hygiene fell into the ambit of occupational health nursing. Over 70% were positive about receiving theoretical and practical hygiene training. Constraints to greater hazard identification included limited time and resources and concern about intruding into the domains of other practitioners. Sufficient numbers of occupational health nurses were interested in identifying hazards in the workplace for training courses to be planned and offered now; however, restraints to practice need to be clarified and removed for these new skills to be used effectively.

Attitude of Health Personnel↗
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↗