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Biomedical subjects

J van Heerden

Publications and source records attributed to J van Heerden.

At least 19 recordsLinked to original sources
PubMed2005

Detection and risk assessment of adenoviruses in swimming pool water.

AIMS: The role of swimming pool water as a source of human adenovirus (HAd) infection has previously been demonstrated. In this study, the risk of infection of HAds detected in a survey of swimming pool water from two indoor and one outdoor swimming pools over a period of 1 year was assessed. METHODS AND RESULTS: The HAds were concentrated from 1 l grab samples of swimming pool water using a silicon dioxide-based method. The extracted HAd DNA was amplified by means of a nested PCR method. Adenoviruses were detected in four of 26 samples (15.4%) from the indoor swimming pool A, eight of 38 samples (21.1%) from the indoor swimming pool B and three of 28 samples (10.7%) from the outdoor swimming pool C. Application of these results in an exponential risk assessment model indicated a daily risk of infection of 2.61 x 10(-3) for swimming pool A, 3.69 x 10(-3) for swimming pool B and 1.92 x 10(-3) for swimming pool C assuming a daily consumption of 30 ml of swimming pool water. CONCLUSIONS: No acceptable (tolerable) risk of infection has yet been recommended for swimming pool water. However, the quality of swimming pool water is generally expected to be similar to that of drinking water. One infection per 10 000 consumers per year has been recommended for drinking water. The risk of HAd infections calculated for the swimming pool water under investigation exceeded this acceptable risk. SIGNIFICANCE AND IMPACT OF THE STUDY: The finding that swimming pool water which conforms to generally accepted specifications for treatment, disinfection and indicator organisms constituted a risk of HAd infection, has implications for the swimming pool industry. The formulation of acceptable (tolerable) risks of infection for swimming pool water may be essential. Specifications will, therefore, have to be formulated to ensure that swimming pool water conforms to the acceptable risk of infection.

Adenoviridae↗
PubMed2005

Prevalence, quantification and typing of adenoviruses detected in river and treated drinking water in South Africa.

AIMS: Human adenoviruses (HAds), of which there are 51 serotypes, are associated with gastrointestinal, respiratory, urinary tract and eye infections. The importance of water in the transmission of HAds and the potential health risks constituted by HAds in these environments are widely recognized. Adenoviruses have not previously been quantified in river and treated drinking water samples. In this study, HAds in river water and treated drinking water sources in South Africa were detected, quantified and typed. METHODS AND RESULTS: Adenoviruses were recovered from the water samples using a glass wool adsorption-elution method followed by polyethylene glycol/NaCl precipitation for secondary concentration. The sensitivity and specificity of two nested PCR methods were compared for detection of HAds in the water samples. Over a 1-year period (June 2002 to July 2003), HAds were detected in 5.32% (10/188) of the treated drinking water and 22.22% (10/45) of river water samples using the conventional nested PCR method. The HAds detected in the water samples were quantified using a real-time PCR method. The original treated drinking water and river water samples had an estimate of less than one copy per litre of HAd DNA present. The hexon-PCR products used for typing HAds were directly sequenced or cloned into plasmids before sequencing. In treated drinking water samples, species D HAds predominated. In addition, adenovirus serotypes 2, 40 and 41 were each detected in three different treated drinking water samples. Most (70%) of the HAds detected in river water samples analysed were enteric HAds (serotypes 40 and 41). One HAd serotype 2 and two species D HAds were detected in the river water. CONCLUSIONS: Adenoviruses detected in river and treated drinking water samples were successfully quantified and typed. The detection of HAds in drinking water supplies treated and disinfected by internationally recommended methods, and which conform to quality limits for indicator bacteria, warrants an investigation of the risk of infection constituted by these viruses. The risk of infection may have implications for the management of drinking water quality. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is unique as it is the first report on the quantification and typing of HAds in treated drinking water and river water. This baseline data is necessary for the meaningful assessment of the potential risk of infection constituted by these viruses.

Adenovirus Infections, Human↗
PubMed2004

Prevalence of human adenoviruses in raw and treated water.

Human adenoviruses (HAds), of which there are 51 antigenic types, are associated aetiologically with gastrointestinal, respiratory, urinary tract and eye infections. The clinical importance of HAds and the potential health risks constituted by HAds in water environments are widely recognised. This study was conducted to assess the use of an optimised integrated cell culture molecular-based technique to determine the prevalence of HAds in raw and treated drinking-water supplies in South Africa. Selected supplies were monitored weekly for the presence of adenoviruses over a one-year period (July 2001 to June 2002). Drinking-water supplies were derived from acceptable quality surface water sources using treatment processes that conformed to international standards for the production of safe drinking water. Adenoviruses were detected by amplification in cell cultures, followed by amplifying the extracted nucleic acids using molecular techniques (nested PCR). HAds were detected in 29.8% (59/198) of the treated drinking water, 16% (8/50) of dam water and 44% (22/50) of river-water samples tested. The results of this study confirmed the presence of HAds in some raw and treated drinking water supplies in South Africa.

Adenoviridae↗
PubMed2002

Clinical and serological response of wild dogs (Lycaon pictus) to vaccination against canine distemper, canine parvovirus infection and rabies.

Wild dogs Lycaon pictuis (n = 8) were vaccinated 4 times against canine distemper (n = 8) (initially with inactivated and subsequently with live attenuated strains of canine distemper) and canine parvovirus infection (n = 8) over a period of 360 days. Four of the wild dogs were also vaccinated 3 times against rabies using a live oral vaccine and 4 with an inactivated parenteral vaccine. Commercially-available canine distemper, canine parvovirus and parenteral rabies vaccines, intended for use in domestic dogs, were used. None of the vaccinated dogs showed any untoward clinical signs. The inactivated canine distemper vaccine did not result in seroconversion whereas the attenuated live vaccine resulted in seroconversion in all wild dogs. Presumably protective concentrations of antibodies to canine distemper virus were present in all wild dogs for at least 451 days. Canine parvovirus haemagglutination inhibition titres were present in all wild dogs prior to the administration of vaccine and protective concentrations persisted for at least 451 days. Vaccination against parvovirus infection resulted in a temporary increase in canine parvovirus haemagglutination inhibition titres in most dogs. Administration of both inactivated parenteral and live oral rabies vaccine initially resulted in seroconversion in 7 of 8 dogs. These titres, however, dropped to very low concentrations within 100 days. Booster administrations resulted in increased antibody concentrations in all dogs. It was concluded that the vaccines were safe to use in healthy subadult wild dogs and that a vaccination protocol in free-ranging wild dogs should at least incorporate booster vaccinations against rabies 3-6 months after the first inoculation.

Animals↗
PubMed2001

Biolog for the determination of microbial diversity in activated sludge systems.

In this study, different carbon source profiles were generated by inoculating Biolog GN microwell plates, with different dilutions of microbial communities from a number of activated sludge systems. This led to the successful generation of patterns reflecting diversity and evenness in the different systems. The high number of substrates utilized at the lower dilutions (10(-1) and 10(-2)) indicated a high microbial diversity in the community, but not necessarily evenness of each species. Evenness of each species was reflected upon further dilution. Our results indicated differences in the microbial community composition amongst some of the activated sludge systems studied. These differences were not specifically related to phosphate removing and non phosphate removing systems.

Bacteria↗
PubMed1999

Cryptococcosis in captive cheetah (Acinonyx jubatus): two cases.

Cryptococcus neoformans is a yeast-like organism associated with pulmonary, meningoencephalitic, or systemic disease. This case report documents 2 cases of cryptococcosis with central nervous system involvement in captive cheetah (Acinonyx jubatus). In both cases the predominant post mortal lesions were pulmonary cryptococcomas and extensive meningoencephalomyelitis. Both cheetahs tested negative for feline immunodeficiency virus and feline leukaemia virus. The organism isolated in Case 2 was classified as Cryptococcus neoformans var. gattii, which is mainly associated with disease in immunocompetent hosts.

Acinonyx↗
PubMed1998

Expression of p27kip1 and Ki-67 in benign and malignant thyroid tumors.

Thyroid neoplasms represent a broad spectrum of tumors with different biologic behaviors. The majority of these tumors can be readily diagnosed by characteristic histopathologic features, but the distinction between follicular adenomas and follicular carcinomas can be difficult. Recent studies with cell cycle proteins such as p27kip1 (p27), a cell cycle inhibitory protein, and Ki-67, a proliferation marker, suggest that these markers might be useful in predicting the behavior of various neoplasms. We analyzed 95 thyroid lesions (16 follicular adenomas, 23 follicular carcinomas, 22 papillary carcinomas, 27 anaplastic carcinomas, plus 7 non-neoplastic thyroids [NNTs], used as a control group) for expression of p27 and Ki-67 by immunostaining. The distribution of immunoreactivity was analyzed by quantifying nuclear staining in each case without knowledge of the diagnosis or outcome. Clinical history and follow-up information were obtained by chart review. There were significant differences in the expression of p27 between follicular adenomas (labeling index [LI] = 47.9+/-5.6) and follicular carcinomas (LI = 15.7+/-2.0). Papillary carcinomas (LI = 11.6+/-3.0) and anaplastic carcinomas (LI = 9.4+/-1.7) had p27 LIs similar to that of follicular carcinomas; the NNT group had the highest p27 LI (74.1+/-4.9). The Ki-67 LI of anaplastic carcinomas (57.6+/-3.8) was more than threefold greater than that of any other group. Logistic regression showed that p27 was effective in distinguishing follicular adenomas from follicular carcinomas (P = .0056) and that Ki-67 could also distinguish follicular adenomas from follicular carcinomas (P = .0060). Analysis of follicular carcinomas with and without metastases showed significantly higher expression of Ki-67 in patients with metastases (P = .0019). These results indicate that antibodies to p27 and Ki-67 might be useful in distinguishing between thyroid neoplasms that are difficult to diagnose by the usual histopathologic criteria.

Adenocarcinoma, Follicular↗
PubMed1997

Thyroidal radioisotope uptake in euthyroid cats: a comparison between 131I and 99mTcO4.

Two thyroidal evaluation systems in euthyroid cats (n = 12) were compared. A single, confirmed hyperthyroid cat was included for interest. Firstly, thyroidal uptake of an intravenous bolus of approximately 111 MBq (3 mCi) 99MTcO4 was estimated by using a scintillation camera and calculating the ratio of thyroid to salivary activities at 20 min and 4 h. Thyroid to salivary activity ratios were 1:1 at 20 min and 2:1 at 4 h. Two discrete areas of salivary uptake were identified, namely a parotid/mandibular complex and a more rostral buccal/sublingual complex. These results were compared to radioiodine uptake of an oral dose of approximately 0.925 MBq (25 microCi) 131I using a standard thyroid uptake system, measured at 1, 2, 4, 6, 8, 10, 12, 24 and 48 h after administration. Mean radioiodine thyroidal uptake started at 33% at 1 h, stabilised at 21% between 4 and 24 h, and dropped to 18% at 48 h. There was a significant correlation between the early thyroid:salivary ratio of the parotid/mandibular complex and the radioiodine uptake at 12 h.

Animals↗
PubMed1996

Management of premature rupture of the membranes after 34 weeks' gestation -- early versus delayed induction of labour.

OBJECTIVE: To determine the optimal way to manage patients with premature rupture membranes after 34 weeks' gestation. DESIGN: A prospective, randomised controlled trial comparing immediate induction and delayed induction after 24 - 48 hours. SETTING: Tygerberg Hospital, Cape Town. PARTICIPANTS: Seventy consecutive patients with premature rupture of the membranes who presented at Tygerberg Hospital between July and October 1991. MAIN OUTCOME MEASURES: The two groups were compared with regard to infectious morbidity and antibiotic requirement in the mothers and babies, days spent in hospital, caesarean section rates, duration of labour and analgesic requirements. RESULTS: There was no difference between the two groups in terms of infectious morbidity in either the mothers or the babies, the duration of labour or the caesarean section rates. Nine patients (26%) in the delayed induction group required analgesic treatment during labour versus 18 patients (52%) in the group that was induced immediately (P = 0.049; odds ratio = 0.327; 95% confidence limits = 0.014 - 0.0998). In the delayed induction group, 74% of the patients went into spontaneous labour during the conservative management period. Patients in the active group (immediate induction) had a statistically significant better chance of being discharged within 48 hours of admission (P = 0.028; odds ratio = 3.34; 95% confidence limits = 1.12 -10.73). CONCLUSIONS: The management of patients with premature rupture of the membranes afer 34 weeks should be decided upon according to the level of antepartum and neonatal care which is available at the particular unit. Where there is adequate neonatal support and pressure on bed occupancy, immediate induction of labour should be considered, while peripheral units should consider conservative management before referral of patients.

Adolescent↗
PubMed1996

The meaning of the MASA apology.

The South African medical profession last year offered a collective apology for its role in supporting apartheid in the past--by restricting admissions to medical schools on the basis of race, by segregating health facilities voluntarily, and by tolerating police interference in the treatment of detainees and prisoners. This article questions the validity of a collective apology on behalf of the profession when individual doctors have not disclosed their own involvement in human rights violations. As the newly established Truth and Reconciliation Commission listens to the stories of more and more victims who experienced abuse at the hands of state doctors during the apartheid ear, the medical profession has an ethical obligation to take strong, corrective action to deal with its past This article proposes that the Medical Association of South Africa and the Medical and Dental Council undertake a "parallel process' of healing that involves truth-telling, forgiveness, and reparation. The article argues that the creation of a Truth Commission for Doctors would have a healing effect on the profession, that it would help ensure that human rights violations of the past never happen again, and that the profession assumes greater responsibility for the ethical conduct and training of future doctors.

Complicity↗
PubMed1996

Disease and mortality in captive wild dogs (Lycaon pictus).

A retrospective survey on the causes of disease and death in captive wild dogs (Lycaon pictus) (n = 87) presented for examination and investigation from 1983 to 1995, revealed that 50 were less than a week old, 13 were between a week and 1 year of age, 7 were less than 5 years old, and 6 were older than 5 years. The age of 11 adult dogs could not be determined. The cause of death could not be determined in the majority of neonates but 37 probably died of exposure and 13 of septicaemia and pulmonary lesions. Various causes of trauma, including aggression and siblicide, were diagnosed in 13 wild dogs. Lesions of the lungs, kidneys, heart, pancreas, uterus, intestines and skin were diagnosed respectively in 4, 6, 3, 3, 5, 5 and 2 of the cases. An aberrant behavioural pattern was diagnosed in a hand-reared wild dog.

Age Distribution↗
PubMed1995

Handling-induced stress and mortalities in African wild dogs (Lycaon pictus).

Recently it was suggested that the handling of wild dogs (Lycaon pictus) by researchers in the Serengeti ecosystem created stress, resulting in the reactivation of latent rabies viruses in carrier animals. We present data from ongoing studies on free-ranging and captive wild dogs elsewhere in Africa which do not support this hypothesis. Cortisol profiles suggest that immobilization of wild dogs does not cause the chronic stress required for stress-reactivation of latent viruses. Furthermore, there is no evidence of handling-related mortalities in wild dogs: the survivorship of unhandled and handled free-ranging wild dogs did not differ and no captive animals died within a year of handling (immobilization and/or vaccination against rabies). We suggest that the mortalities observed in Tanzania were due to an outbreak of a disease which rabies vaccination was unable to prevent. Intensive monitoring and active management research programmes on wild dogs are essential as without these, critically endangered wild dog populations have little hope of survival.

Africa↗
PubMed1993

Experimental vermeersiekte (Geigeria ornativa O. Hoffm. poisoning) in sheep. I: An evaluation of diagnostic aids and an assessment of the preventive effect of ethoxyquin.

Dried milled Geigeria ornativa, which had been stored at room temperature for 4 years, was fed in rations to sheep. The usefulness of contrast radiography of the oesophagus, biopsies of oesophageal and skeletal muscles, electrocardiography, and clinical pathological parameters for diagnosing vermeersiekte were evaluated. Ethoxyquin was evaluated as a preventive agent. All the sheep developed signs of vermeersiekte but regurgitation was observed in only one animal. Contrast radiography and the examination of tissue biopsies were of diagnostic value in 8 out of 13 and 6 out of 6 sheep respectively. Electrocardiography did not aid in antemortal diagnosis of the condition and selected chemical parameters were non-specific. The inclusion of ethoxyquin in the diet of experimental animals (n = 3) prior to and during feeding of G. ornativa did not prevent the development of vermeersiekte. This study confirmed that dried stored G. ornativa retains its toxicity and that regurgitation is not a consistent clinical sign in sheep with vermeersiekte. The diagnostic value of contrast radiography of the oesophagus and examination of oesophageal and muscle biopsies is reported for the first time.

Animals↗
PubMed1993

Experimental vermeersiekte (Geigeria ornativa O. Hoffm. poisoning) in sheep. II: Histological and ultrastructural lesions.

The histological and ultrastructural lesions of sheep (n = 5) with experimentally-induced vermeersiekte (Geigeria ornativa O. Hoffm. poisoning) were studied. Histological changes in the muscles of the skeletal system, diaphragm and oesophagus comprised hypertrophy and vacuolation of myofibres. In 2 sheep, foci of myocardial degeneration and necrosis were present. No microscopical changes were detected in the central nervous system and in peripheral nerves of the oesophagus and the hind limb. Ultrastructural alterations in the myocardium, semimembranosus muscle and oesophagus were characterised by concurrent myofibrillar degeneration and mitochondrial swelling. The earliest myofibrillar change appeared to be loss of the thick filaments followed by fragmentation and disorganisation and eventually by lysis of central myofibrils. Focal thickening, fragmentation and clumping of Z-band material and dissociation and fragmentation of intercalated discs accompanied the myofibrillar and mitochondrial alterations.

Animals↗