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Biomedical subjects

D Rees

Publications and source records attributed to D Rees.

At least 19 recordsLinked to original sources
PubMed2003

Epstein-Barr virus-related post-transplant lymphoproliferative disorder with t(9;14)(p11-12;q32).

The immunoglobulin heavy chain gene locus on 14q32 is known to be involved in translocations that are associated with B-lymphoproliferative disorders, typically Burkitt lymphoma and B-cell acute lymphoblastic leukemia. Several cytogenetic abnormalities have been described in post-transplant lymphoproliferatve disease (PTLD), some of which include this locus. To our knowledge, we report the first case of translocation t(9;14)(p11-12;q32) in a PTLD that developed after orthoptic liver transplantation.

Biliary Atresia↗
PubMed2002

Tibial cyst formation after anterior cruciate ligament reconstruction using a new bioabsorbable screw.

We report a case of tibial cyst formation twelve months after anterior cruciate ligament reconstruction using hamstring graft. A composite bioabsorbable interference screw made of 'beta tricalcium phosphate and poly L-lactide' fixed the graft distally. The patient presented with acute symptoms of pain and swelling over the proximal tibia. Curettage of the cyst resulted in complete recovery within 3 months.

Absorbable Implants↗
PubMed2001

Assessment of Australian Trichogramma species (Hymenoptera: Trichogrammatidae) as control agents of stored product moths.

Trichogramma species (T. brassicae, T. pretiosum and T. carverae) were assessed for their suitability as bio-control agents against Ephestia cautella and E. kuehniella which are important pests in food manufacturing and processing facilities in Australia. Parameters examined were longevity, fecundity on eggs of E. kuehniella, walking speed of adult wasps, reaction to moth scales, and host acceptance and host suitability of eggs of E. cautella and E. kuehniella. T. pretiosum and T. carverae performed better than T. brassicae in all traits examined apart from fecundity. T. pretiosum and T. carverae differ mainly in higher fecundity and host acceptance in T. pretiosum, and a better host-finding ability (walking speed, reaction to moth scales) in T. carverae. The suitability of the Trichogramma species for use as control agents is discussed with respect to these results.

Journal Article↗
PubMed2001

Occupational asthma as identified by the Surveillance of Work-related and Occupational Respiratory Diseases programme in South Africa.

BACKGROUND: The nationwide Surveillance of Work-related and Occupational Respiratory Diseases in South Africa, SORDSA, was established in 1996 to provide systematic information on occupational respiratory diseases. OBJECTIVE: SORDSA's objectives are to monitor the nature, extent and distribution of occupational respiratory diseases, and to increase awareness of their diagnosis and prevention. This paper describes the programme and results obtained for occupational asthma in the first 2 years, ending in October 1998. METHODS: SORDSA identifies newly diagnosed cases of occupational respiratory disease through voluntary reporting by pulmonologists, occupational medicine doctors and occupational health nurses. Initially, recruitment of the above health care providers was done through the membership infrastructure of their respective professional societies. Booklets with prescribed monthly reporting forms were distributed annually to all reporting members and a core of reporting providers was established through a proactive method of data collection. Information dissemination and reporting feedback takes place through quarterly newsletters and issue-specific brochures on certain hazardous agents. RESULTS: Over the initial 2-year period, 3285 cases of occupational respiratory disease were reported to SORDSA by 203 doctors and 97 occupational health nurses. After pneumoconiosis and associated respiratory conditions, occupational asthma was the second most commonly reported disease with 225 cases (6.9%). The average annual incidence for occupational asthma in South Africa was 13.1 per million employed people, with the highest incidence reported from the Western Cape province (37.6 per million). Latex was the most frequently reported agent for occupational asthma, followed by isocyanates and platinum salts. Low molecular weight agents accounted for 59.6% of the cases of occupational asthma. CONCLUSION: The results from this initial phase show that despite some limitations, SORDSA has the potential to obtain useful data on the industries, agents and occupations causing occupational asthma in South Africa.

Asthma↗
PubMed2001

Sequence analysis of the rat phenylalanine hydroxylase gene promoter.

We have characterized the 5'-end (3218 bp) of the rat phenylalanine hydroxylase (PAH) gene. Within this PAH promoter sequence, we have identified a number of putative regulatory sites analogous to those present in the human and murine PAH promoters. In particular, potential HNF 1 binding sites and a CRE have been identified. These sequences respectively bind HNF1 and CREB transcription factors present in rat nuclear extracts and may be significant in the tissue-specific and hormonal control of PAH expression.

5' Flanking Region↗
PubMed2001

Occupational respiratory diseases in South Africa--results from SORDSA, 1997-1999.

OBJECTIVES: To describe the nature and extent of work-related respiratory diseases reported to the national Surveillance of Work-related and Occupational Respiratory Diseases in South Africa (SORDSA) reporting scheme. The causative agents and industrial categories in which they occurred are also characterised. DESIGN: Voluntary monthly reporting of newly diagnosed cases by pulmonologists, occupational medicine practitioners and occupational health nurses. SETTING: Medical and occupational health referral centres in the nine provinces of South Africa. SUBJECTS: Cases were workers from non-mining industries or ex-miners, suffering from a newly diagnosed occupational respiratory disease, reported to SORDSA between October 1996 and December 1999. OUTCOME MEASURES: Frequencies of reported occupational respiratory disease by year, reporting source, province and sex. Frequencies of short- and long-latency diseases by industry and causative agent. RESULTS: There was incomplete reporting coverage of the nine provinces in the first 3 years. Reporting was most comprehensive from Gauteng, KwaZulu-Natal and the Western Cape. Diseases with long latency periods made up 76.2% of the cases. Pneumoconiosis, even in non-mining industries, was the most frequently reported disease, followed by inhalation accidents. Occupational asthma was the fourth most reported disease. Apart from the prominence of pneumoconiosis, the results obtained by SORDSA are similar to those from a British occupational lung disease surveillance scheme. This study showed that newly diagnosed cases of occupational lung disease occurred in many industries and were caused by a variety of agents. CONCLUSION: SORDSA has contributed insight into the nature, extent and distribution of occupational respiratory diseases in South Africa. It has also highlighted important causes of occupational respiratory diseases in South Africa, as well as hazardous industries. The data indicate that South Africa has a widespread occupational lung disease problem, and provide a platform for targeted prevention strategies.

Accidents, Occupational↗
PubMed2001

Occurrence and causes of occupational asthma in South Africa--results from SORDSA's Occupational Asthma Registry, 1997-1999.

OBJECTIVE: To present results for the first 3 years of the occupational asthma registry of the Surveillance of Work-related and Occupational Respiratory Diseases in South Africa (SORDSA) programme, ending December 1999. DESIGN: Surveillance was accomplished by collecting voluntary reports of occupational asthma cases from pulmonologists, occupational medicine practitioners and occupational health nurses. SETTING: Medical and occupational health referral centres in the nine provinces of South Africa. SUBJECTS: Patients diagnosed with new-onset occupational asthma with latency or irritant-induced asthma, reported to SORDSA during 1997-1999. OUTCOME MEASURES: Frequencies of cases, causative agents, industries causing exposure and diagnostic methods. Average annual incidence rates by province and by occupation. RESULTS: During this period 324 cases of occupational asthma were reported. The average annual incidence rate of occupational asthma was estimated in the three best-reporting provinces, namely Gauteng, KwaZulu-Natal and the Western Cape, as 17.5 per million employed people annually. This rate was highest in the Western Cape (25.1 per million). Semi-skilled operators had the highest incidence rate of 68.7 per million annually in the three provinces. Isocyanates and latex were the most common agents. Low molecular weight causative agents predominated (68.8%) over high molecular weight agents. Health care was the most frequently reported workplace for occupational asthma (OA) development. Serial peak flow testing was the method most often used for diagnosis. One-fifth of the cases were still occupationally exposed to the causative agent at time of diagnosis. CONCLUSION: Despite underreporting, SORDSA's estimate of the occupational asthma incidence rate was similar to that of the UK. SORDSA has also demonstrated that surveillance programmes in a developing country can provide useful information on which to base prevention activities.

Asthma↗
PubMed2001

Asbestos lung fibre concentrations in South African chrysotile mine workers.

Mesothelioma has not been found in South African chrysotile miners and millers despite decades of producing about 100000 tons of the mineral per year. One possible explanation for the scarcity or absence of the cancer may be a relative lack of contaminating fibrous tremolite, an amphibole that variably occurs with chrysotile ores. The fibre content in the lungs of nine former chrysotile mine workers was ascertained by transmission electron microscopy. Despite fairly long service in most cases (median 9.5 yr; range 32-4 yr) the concentrations of chrysotile fibres were relatively low: only two cases exceeded 1.14 million fibres/g dried lung. Tremolite fibre levels were even lower: less than 1 million fibres/g dried lung in all but one case. Tremolite fibre concentrations exceeded those of chrysotile in only two cases. These results support the contention that South African chrysotile is not heavily contaminated by tremolite.

Adult↗
PubMed2000

Risk of mesothelioma from exposure to crocidolite asbestos: a 1995 update of a South African mortality study.

OBJECTIVE: To find the risk of developing mesothelioma in a cohort born in 1916-36 in Prieska, Northern Cape Province, South Africa. METHODS: A birth cohort mortality study was carried out in a small town in the Northern Cape Province, South Africa, with a history of crocidolite asbestos mining and milling. The cohort comprised all white births registered in the magisterial district of Prieska from 1916 to 1936, inclusive (2390). Causes of death due to mesothelioma and other cancers as recorded on medical certificates of cause of death were investigated. Person-years analysis was used to calculate mortalities due to mesothelioma, other respiratory cancers, and other non-respiratory cancers. Proportional cancer mortalities were also calculated for mesothelioma and other specific neoplasms. RESULTS: The follow up rate for the cohort was 74.3% in 1995, and 683 traced members (38.6%) had died. Cause of death was unknown for 6.4% of deaths. There were 118 cases of cancer, 28 of them from mesothelioma, giving a cause specific mortality for mesothelioma of 277 (170-384) per 10(6) person-years. The rates for men and women were 366 and 172 per 10(6) person-years, respectively. The mortality for lung cancer (29 deaths) was 287 (135-436) per 10(6) person-years, and that for other non-respiratory cancers (60 deaths) was 593 (442-745). Two cases of laryngeal and four of colon cancer were observed. All cancer mortality, mesothelioma, and lung cancer proportional cancer mortality ratios were increased. CONCLUSION: The mortality for mesothelioma in men was twice that in women, probably because men were more likely to have had both occupational and environmental exposure to asbestos. Nevertheless, the mortality in women was still high and is probably indicative of the environmental exposure as white women were rarely employed in the asbestos industry in the Prieska area. Due to the long latency from first exposure to diagnosis of the neoplasm, the cause specific mortality in this cohort could be expected to increase rapidly over the next 10 years.

Adolescent↗
PubMed2000

Pseudoaneurysm of the medial inferior genicular artery following anterior cruciate ligament reconstruction.

Pseudoaneurysm is a rare complication of surgery or trauma around the knee. A 30-year-old man presented 10 days following anterior cruciate ligament repair with a 2 cm pulsatile swelling on the medial side of the knee. Angiography demonstrated a pseudoaneurysm of the medial inferior genicular artery. Surgical exploration and ligation of the feeding vessel to the aneurysm was performed and the patient made a full recovery. Vascular injury must be suspected in patients presenting with a haemarthrosis or pulsatile swelling following surgery on the knee.

Adult↗
PubMed1999

Apolipoprotein A-I stimulates secretion of apolipoprotein E by foam cell macrophages.

Apolipoprotein A-I (apoA-I) overexpression inhibits atherogenesis in mice, and apolipoprotein E (apoE) secreted by foam cell macrophages may exert antiatherogenic effects within the arterial wall. We hypothesized that interaction between apoA-I and apoE contributed to the antiatherogenic properties of apoA-I, and therefore investigated whether apoA-I stimulated secretion of apoE by foam cell macrophages. Cholesterol enrichment of primary murine and human macrophages increased spontaneous apoE secretion 2-fold, as quantified by Western blot and chemiluminescence detection. Human apoA-I caused a further marked increase of apoE secretion from both murine (3.8-fold, p < 0.01) and human (3.2-fold, p = 0.01) foam cells in a time- and concentration- dependent manner, and this increase was confirmed by immunoprecipitation of [(35)S]methionine-labeled macrophage apoE. The protein synthesis inhibitor cycloheximide, but not the transcription inhibitor actinomycin D, markedly inhibited apoE secretion to apoA-I (73.1 +/- 9.8% inhibition at 4 h) and completely suppressed apoE secretion beyond 4 h. Pretreatment of macrophages with Pronase inhibited initial apoA-I-mediated apoE secretion by 70.5 +/- 6.5% at 2 h, but by 8 h apoA-I-induced apoE secretion was the same in Pronase-pretreated and non-pretreated cells. Non-apolipoprotein-mediated cholesterol efflux induced by trimethyl-beta cyclodextrin did not enhance apoE secretion, whereas phospholipid vesicles inducing the same degree of cholesterol efflux substantially enhanced apoE secretion, and apoA-I and phospholipid vesicles in combination demonstrated additive induction of apoE secretion. We conclude that apoA-I concurrently stimulates apoE secretion and cholesterol efflux from foam cell macrophages and that lipoprotein-derived apoA-I may enhance local secretion and accumulation of apoE in atherosclerotic lesions.

Animals↗
PubMed1999

Case-control study of mesothelioma in South Africa.

BACKGROUND: South Africa has, uniquely, mined, transported, and used crocidolite, amosite, and chrysotile. A multicenter case-control study was done in South Africa to examine the details of asbestos exposure in cases and controls, and to calculate relative risks for level of certainty of asbestos exposure, nature of exposure (e.g., environmental, occupational) and fiber type. METHODS: Cases and controls (one cancer and one medical per case) were collected by six study centers from referral hospitals, and exposure information was collected by interviewing cases and controls in life. RESULTS: One hundred and twenty-three cases were accepted into the study. None had purely chrysotile exposure. Twenty-three cases had mined Cape crocidolite; three had mined amosite; and three Transvaal crocidolite plus amosite. A minimum of 22 of the cases had exclusively environmental exposure, 20 were from the NW Cape crocidolite mining area. The relative risks associated with environmental exposure in the NW Cape (crocidolite) were larger than for environmental exposure in the NE Transvaal (amosite and crocidolite): 21.9 vs. 7.1 and 50.9 vs. 12.0 for the cancer control and medical control datasets, respectively. CONCLUSIONS: The results confirm the importance of environmental exposure in the Cape crocidolite mining area, the relative paucity of cases linked to amosite, the rarity of chrysotile cases and are consistent with a fiber gradient in mesotheliomagenic potential for South African asbestos with crocidolite > amosite > chrysotile.

Asbestos↗
PubMed1999

Allergy to complex salts of platinum in refinery workers: prospective evaluations of IgE and Phadiatop status.

BACKGROUND: Experience has shown some variation in the associations between IgE, atopy, and sensitization to platinum salts. Clarification of these associations, and the value of the parameters in predicting and diagnosing sensitization of workers at risk, required prospective investigation. OBJECTIVES: Evaluation of total IgE and Phadiatop(R) status to establish baseline values, and changes during employment, predictive or associated with subsequent platinum salt sensitization. METHODS: A 24-month prospective study, in a South African primary platinum refinery, of a cohort of 78 healthy recruits without evidence of atopy (tested negative to skin prick test with common allergens). Subsequently they were categorized as 22 sensitized (positive skin prick test to platinum salts), 46 not sensitized (negative skin prick test and symptom free), and 10 symptomatic subjects not included in either category. RESULTS: (1) Pre-employment: four (18%) of the subsequently sensitized subjects and eight (17%) not sensitized were Phadiatop(R) positive. Levels of total IgE > 100 kU/L, present in 16 subjects were associated with positive Phadiatop(R) status and race. (2) During employment: Phadiatop(R) status converted from negative to positive in more sensitized (12/18) than unsensitized (6/38) subjects (P </= 0.0001). Total IgE levels at outcome had increased in more sensitized subjects, and median levels were higher than in unsensitized subjects (17 (77%) vs six (13%), and 92 vs 26 kU/L, P = 0.0015). Multivariate analysis showed the likelihood of an increase in total IgE was nine times greater in subjects sensitized to platinum salts, and five times greater with higher platinum salt exposure. Specific IgE was demonstrated, generally in only one sample of the series, in two sensitized and three unsensitized subjects. Positive responses to skin prick tests with common allergens occurred in five (23%) sensitized and 11 (24%) unsensitized subjects. CONCLUSION: Platinum salt sensitivity was not predicted by pre-employment Phadiatop(R) or IgE status, but was subsequently associated with conversion to positive Phadiatop(R) status, and an increase in total IgE (independent of Phadiatop(R) status).

Cohort Studies↗
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↗