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Biomedical subjects

M Steyn

Publications and source records attributed to M Steyn.

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

Familial hyperhomocysteinaemia and endothelium-dependent vasodilatation and arterial distensibility of large arteries.

OBJECTIVES: Mild hyperhomocysteinaemia, fasting as well as after a methionine load, occurs in families and is associated with premature atherosclerosis. We hypothesised that endothelial dysfunction plays a role in the relation between hyperhomocysteinaemia and clinical vascular disease. METHODS: In this study flow-mediated, endothelium-dependent vasodilatation of the brachial artery and, as a marker of biophysical changes of the vessel wall such as increased smooth muscle cell tone or collagen formation, arterial distensibility of the common carotid artery were investigated in 123 healthy first-degree relatives of patients with mild hyperhomocysteinaemia and coronary, cerebral or peripheral artery disease. RESULTS: In multiple linear regression analyses, the increase in the homocysteine concentration after a standard methionine load was a significant determinant of an impaired flow-mediated vasodilatation of the brachial artery (measured on a separate day). The only other predictors were the baseline vessel diameter and age. Fasting homocysteine level was not associated with flow-mediated vasodilatation in the brachial artery. There was no relationship between homocysteine levels and nitroglycerine-induced, endothelium-independent vasodilatation of the brachial artery. Arterial distensibility of the carotid artery was also not related to homocysteine levels. CONCLUSIONS: In healthy first-degree relatives of patients with mild hyperhomocysteinaemia, the increase in homocysteine level after a methionine load is an independent predictor of endothelial dysfunction. The results also suggest that fasting and post-methionine homocysteine levels may reflect distinct disturbances in methionine metabolism, which may be linked to vascular dysfunction through distinct mechanisms.

Adult↗
PubMed1999

Sex steroids, insulin, and arterial stiffness in women and Men.

Arterial stiffness may be influenced by sex steroids and insulin; the association with fasting insulin level may be stronger in women than in men. Therefore, we analyzed the effects of sex steroid administration on (1) arterial stiffness and (2) the relationship between fasting insulin level and arterial stiffness. Twelve male-to-female transsexuals were treated with ethinyl estradiol and cyproterone acetate, and 18 female-to-male transsexuals were treated with testosterone esters, with assessments made at baseline and after 4 and 12 months. Changes in distensibility and compliance coefficients (DC and CC, respectively) of the common carotid artery, femoral artery (FA), and brachial artery (BA) were analyzed in relation to changes in fasting plasma levels of glucose, insulin, HDL-cholesterol, and triglycerides. After 4 months of estrogens and antiandrogens in men, significant reductions in the CC and DC of the FA (P=0.006 and P=0.04, respectively) and BA (P=0.04 and P=0.04, respectively) were observed. In women, testosterone, on average, did not affect DC or CC, but the changes in fasting insulin level were strongly negatively associated with changes in the CC and DC, especially in the FA and BA. These associations were significantly less strong in genetic men and were independent of age, mean arterial pressure, and glucose and lipid levels. This experimental study shows (1) that short-term administration of estrogens and antiandrogens increases FA and BA stiffness in men and (2) that the fasting insulin level is a stronger determinant of arterial stiffness in women than in men.

Adolescent↗
PubMed1999

The use of a rating instrument to teach and assess communication skills of health-care workers in a clinic in the Western Cape.

Research in health communication shows communication to be an important aspect of successful health-care. Moreover, training courses which provide feedback have been shown to improve health professionals' ability to conduct successful interviews. This article describes a rating instrument which was developed in order to facilitate teaching and assessing the communication aspects of health-care interviews. The instrument was found to be useful in a training programme offered to nursing staff of a TB Clinic in Mitchells Plain, Western Cape. The instrument appears as Table 1. In the Table categories of communication behaviours, each indicating an important aspect of the interaction, are given as the six headings. These are: establishing rapport and respect listening receptively confirming the patient sharing control informing effectively and checking perceptions. Within each category the more detailed specific behaviours are listed, allowing for close analysis of a care-giver's interviewing skill. The article briefly discusses the importance in effective communication between the care-giver and patient of each category of behaviours given in the instrument, supported by evidence from research. Lastly the article describes a "case study" on how the instrument has been successfully used in a training programme.

Clinical Competence↗
PubMed1998

Sexual dimorphism in the crania and mandibles of South African whites.

Numerous studies have clearly demonstrated that skeletal characteristics vary by population. To date, there are no metric cranial criteria for South African whites. Therefore, the purpose of this study is to establish population specific standards for sex determination from the skull. A total of 12 standard cranial and five mandibular measurements were taken from 44 male and 47 female skeletons of known sex and race from the Pretoria and Dart collections. These were subjected to SPSS discriminant function analysis. Bizygomatic breadth was the most dimorphic dimension. Five functions were developed from the complete cranium, vault, face, mandible and bizygomatic breadth. Dimensions from the complete cranium provided the best accuracy. In the mandible, bigonial breadth was the most dimorphic of the measurements taken. Average accuracies ranged from 80% (bizygomatic breadth alone) to 86% (cranium). These accuracies are similar to those obtained by researchers on other groups (e.g., 84% in Japanese crania and about 86% in American whites and blacks). Diagnostic accuracy, however, is lower than that obtained from the South African femur and tibia.

Discriminant Analysis↗
PubMed1998

Correlation among total lymphocyte count, absolute CD4+ count, and CD4+ percentage in a group of HIV-1-infected South African patients.

Depletion of CD4+ T cells is one of the hallmarks of progression of HIV-1 infection. However, measurement of the CD4+ T-cell count is expensive and often unavailable in less developed areas. Previous studies have suggested that the total lymphocyte count (TLC) can be used to predict a low absolute CD4+ T-cell count. To determine the relationship between TLC and CD4+ T-cell count in HIV-1-infected South African patients, 2777 HIV-1-seropositive patients visiting the Immunology clinic at the Pelonomi Hospital in Bloemfontein, South Africa from April 1991 to April 1997 were included in the study. In total, 3237 observations were used to determine sensitivity, specificity, and likelihood ratios, with 95% confidence intervals, of various cutpoints of the TLC to predict an absolute CD4+ T-cell count of <200 cells/mm3, CD4+ percentage <20%, and CD4+ percentage <15%. Spearman rank correlations were calculated between TLC and CD4+ T cells, CD4+ percentage and CD8+ T cells, as well as between CD4+ and CD8+ T cells. Results demonstrated that a TLC of 2 x 10(9)/L or less had a sensitivity of 90.3% to detect patients with a CD4+ T-cell count of <200 cells/mm3, but a specificity of only 53.7%. When the TLC cutoff value was lowered, specificity increased but sensitivity decreased. For the observations as a group, a correlation (r = 0.704) between CD4+ T-cell count and TLC was demonstrated, but if the patients were divided into three groups according to their CD4+ T-cell count, this correlation weakened considerably. Therefore, although TLC shows a correlation with CD4+ T-cell count, it is not a good predictor of the CD4+ T-cell count in this population and should preferably not be used in the clinical care of HIV/AIDS patients.

Adolescent↗
PubMed1998

Endothelium-dependent vasodilatation is impaired in peritoneal dialysis patients.

BACKGROUND: Peritoneal dialysis (PD) patients have a high risk of cardiovascular mortality, which is not completely explained by conventional risk factors. Other factors related to chronic renal failure and/or dialysis treatment might lead to endothelial dysfunction, which is associated with an adverse cardiovascular outcome. One such factor is hyperhomocysteinaemia, which has a high prevalence in PD patients. METHODS: A vessel wall movement detector system was used to investigate endothelium-dependent, flow-mediated, and endothelium-independent, glyceryl trinitrate-induced, vasodilatation of the brachial artery in 29 PD patients and 29 control subjects. RESULTS: Endothelium-dependent vasodilatation was markedly reduced in the PD group: 5.7 +/- 1.0% vs 10.4 +/- 1.3% in the control group (P = 0.004). Endothelium-independent vasodilatation was not impaired. Plasma total homocysteine was elevated in the PD patients (45.2 +/- 6.2 micromol/l), but was not related to endothelium-dependent vasodilatation. CONCLUSION: Chronic peritoneal dialysis patients have impaired endothelium-dependent vasodilatation, which may reflect an increased susceptibility for the development of atherosclerosis and thrombosis.

Arteriosclerosis↗
PubMed1997

Sex determination from the femur and tibia in South African whites.

With the current high incidence of violent crimes in South Africa, it has become very important to be able to determine the sex of individuals from their skeletal remains. The aim of this study is to provide standards usable for this purpose, to be used on the contemporary South African white population. Very little skeletal data is available for this group. Osteometric information was obtained from 56 male and 50 female individuals from cadaver collections. Six femoral and seven tibial measurements were taken, and subjected to SPSS discriminant function analysis. The distal breadths from both the femur and tibia provided the best discrimination. Formulae were developed for a number of combinations of measurements, which can be used to determine the sex on fragmentary remains. Average accuracies ranged from 86% to 91%, with female accuracies slightly higher than those of the males. The results of this study compares well with others, e.g., those from American whites.

Adult↗
PubMed1997

Twelve-year results of the Coronary Risk Factor Study (CORIS).

BACKGROUND: After 4 years a coronary heart disease risk factor intervention programme produced equally large and significantly reduced risk profiles in two intervention towns compared with a control town. Intervention effects through community participation were assessed after cessation of the active intervention programme. The impact of secular trends was assessed in the control town and in two previously unstudied towns. METHODS: Cross-sectional surveys were done in a random sample of 1620 participants aged 15-64 years in the three original towns 12 years after the initial quasi-experimental study. Two years later 327 subjects, aged 35-44 years, were studied in the original control town and in two non-intervention towns. Risk factor knowledge, smoking and medical histories were determined by questionnaire. Blood pressure, anthropometry and blood lipids were recorded. Data were compared across towns, and with previous surveys. RESULTS: At 12 years the low intensity intervention town maintained a significantly better risk factor profile than the control town, while the high intensity intervention town now matched the control town. No differences in risk factor profiles were found between the control town and the two new towns. Deaths from coronary heart disease and strokes showed a downward trend in the study area. CONCLUSIONS: Outcome suggests large ongoing secular trends during the study could have overtaken the intervention effects in the high intensity town, but not in the low intensity intervention town, which showed an advantage over the control town. These results support the effectiveness of media-based, long term health promotion strategies to reduce cardiovascular disease risk profiles.

Adolescent↗
PubMed1997

Communication with TB patients; a neglected dimension of effective treatment?

Previous research has shown that patients who are satisfied with their interactions with a health provider tend to adhere to treatment. This study sets out to investigate the quality of the communication in the interactions between clinic nurses at a Western Cape clinic and newly notified tuberculosis patients. Routine interviews between clinic nurses and tuberculosis patients were video-recorded, transcribed and analysed, using a qualitative instrument devised by the researchers. The interactions were evaluated as being essentially nurse-centred; there was an unequal distribution of control, poor receptivity to the patient and little confirmation of the patient. The nursing staff received a period of training in communication skills. After this training their interviews with patients revealed a significant shift towards a more patient-centred approach, resulting in mutual satisfaction of nurse and patient. Training in communication skills should be introduced at TB clinics, in order to improve patients' adherence to therapy.

Analysis of Variance↗
PubMed1996

Skeletal growth of children from the Iron Age site at K2 (South Africa).

Cross-sectional growth data were obtained from the skeletal remains of children from the Iron Age site of K2 near the Limpopo River. Standard measurements of the diaphyseal lengths of the long bones from both limbs were recorded and compared to published skeletal data. For this purpose, data on Eskimo and Aleut skeletons, Libben skeletons, and skeletons from Indian Knoll and Altenerding were used. An attempt to study growth allometrically was made. K2 children were growing as well as children from these other groups. Comparison of data for K2 children with those on living South African "Cape Coloured" rural children, studied during the late 1980s, shows the similarity of growth of both groups.

Adolescent↗
PubMed1996

Estimation of the prevalence of familial hypercholesterolaemia in a rural Afrikaner community by direct screening for three Afrikaner founder low density lipoprotein receptor gene mutations.

We have determined the prevalence of familial hypercholesterolaemia (FH) in a rural Afrikaner community by means of direct DNA screening for three founder-related Afrikaner low density lipoprotein (LDL) receptor gene mutations. A random sample of 1612 persons, aged 15-64 years, was selected as a subsample of 4583 subjects from an Afrikaner community living in the south-western Cape, South Africa. Participants who had a total serum cholesterol (TC) in the high TC category as defined in the consensus recommendations by the Southern African Heart Foundation, were screened for three founder-related LDL receptor gene mutations, causing FH in 90% of Afrikaners. Of the subsample, 201 participants (12.5%) had TC levels above the 80th percentile. In this group the combined prevalence of the three common Afrikaner LDL receptor gene defects (D206E, FH Afrikaner-1; V408M, FH Afrikaner-2; D154N, FH Afrikaner-3) was calculated as 1: 83. When taking into account the reported background prevalence of other FH gene defects of 1:500 in this community, their overall prevalence of FH was estimated to be 1:72. The significant differences found between the FH patients and other high risk patients with raised cholesterol levels were higher TC and LDL cholesterol levels and lower high density lipoprotein cholesterol levels in FH patients. The treatment status of the molecularly identified FH patients and other hypercholesterolaemic persons suggests that this condition is inadequately diagnosed and poorly managed in this study population. An extrapolation to the entire South African population suggests that there are about 112000 FH patients in the country who are under-diagnosed as a group and therefore not receiving the care that would help to reduce the burden of FH-associated ischaemic heart disease in South Africa.

Adolescent↗
PubMed1994

Preliminary report on the paleodemography of the K2 and Mapungubwe populations (South Africa).

Paleodemographic studies have seldom been attempted in sub-Saharan Africa. The Mapungubwe complex of sites in northern Transvaal (A.D. 970-1200) has yielded enough skeletal material to warrant such an investigation. The skeletal collection consists of 109 individuals (97 from K2 and 12 from Mapungubwe itself). Because the sites are extensive and their complete excavation impractical, only reconstruction of the population dynamics, not the population size, was possible. There were 81 child and juvenile skeletons (below 15 years of age) and 7 male, 5 female, 4 possible male, and 4 possible female adult skeletons. Eight adult skeletons were too fragmentary to warrant even tentative sex diagnoses. Either age-specific burial practices resulting in the surplus of child skeletons, unusual child mortality, or a state of substantial natural increase must be the explanation for this age distribution. The hypothesis of the natural increase can be partly tested by using an appropriate correction to the life table. The life table corrected for r = 2.5% has a newborn life expectancy of 18.93 +/- 1.79 years and a survivorship to 15 years of 41.66% +/- 3.91. The population pyramid derived from this life table compares well with data on some third world populations observed earlier this century. The fertility rate required to maintain the natural increase under such mortality conditions is high but comparable to that of some historical populations. High positive natural increase would indicate an economically successful population.

Age Determination by Skeleton↗
PubMed1993

Community-based intervention: the Coronary Risk Factor Study (CORIS).

The Coronary Risk Factor Study (CORIS) examined the feasibility and effectiveness of a multifactorial community intervention programme to reduce coronary heart disease (CHD) risk factor levels. Three Afrikaner communities were surveyed before and after a 4-year intervention in two of the communities, the third serving as a control (C). Intervention was primarily by small mass media (low-intensity intervention, LII) or by small mass media plus interpersonal intervention to high-risk individuals (high-intensity intervention, HII). After allowing for change in C, significant net reductions in blood pressure, smoking, and risk score were obtained in LII and HII alike. Though the total cholesterol (TC) fell by 10-12%, there was no net reduction in favour of the intervention communities. However, LII and HII resulted in significant increases in high-density lipoprotein cholesterol (HDL-C) levels and HDL-C/TC ratios in comparison to C. Overall, the LII community fared almost as well as the HII community, and high-risk individuals did not show a greater change in risk factors than others. We conclude that community-based intervention works, and that in these particular communities a media-based health education programme was more cost-effective than one which adds a greater degree of interpersonal intervention.

Adolescent↗
PubMed1993

The intervention effects of a community-based hypertension control programme in two rural South African towns: the CORIS Study.

The objective of the hypertension programme of the Coronary Risk Factor Study (CORIS) was to evaluate the effectiveness of the first 4 years of community-based intervention. The hypertension intervention model comprised a blood pressure station where the whole population was screened for hypertension, non-drug management was provided and hypertensives were monitored after referral to general practitioners for drug therapy. Two levels of intervention were maintained: in the high-intensity intervention town (N = 2,278) hypertensives were actively followed up, and in the low-intensity intervention town (N = 2,620) no active follow-up procedure existed. A third town acted as control (N = 2,290). In the cohort which was hypertensive at baseline, the net decreases in systolic blood pressure (mean +/- SE) after correction for changes in the control town were 0.5 +/- 2.2 mmHg (men) and 4.5 +/- 2.2 mmHg (women) in the low-intensity intervention town, and 5.6 +/- 2.3 mmHg (men) and 7.5 +/- 2.2 mmHg (women) in the high-intensity intervention town. The net decrease in diastolic blood pressure was 3.4 +/- 1.2 mmHg (men) and 4.4 +/- 1.1 mmHg (women) in the low-intensity intervention town, and 6.1 +/- 1.2 mmHg (men) and 5.9 +/- 1.1 mmHg (women) in the high-intensity intervention town. These reductions were statistically significant with one exception. The changes in the total population in the 3 communities after 4 years of intervention were similar to those found in the hypertensive cohort.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Multiple intracavitary cardiac masses; an uncommon presentation of African Burkitt's lymphoma.

A 29-yr-old patient is described, who presented with rapid general deterioration and right heart failure. Two-dimensional echocardiography revealed massive intracardiac tumor involving the right atrium, the right ventricle and the left atrium. At histology the diagnosis of Burkitt's lymphoma was made. This report presents what we believe to be the first case of a patient with primary cardiac manifestations and multiple intracardiac masses in this disease.

Adult↗
PubMed1991

Change in knowledge in a coronary heart disease risk factor intervention study in three communities.

We investigated health and diet knowledge as it relates to coronary heart disease (CHD) in three rural areas which participated in a community-oriented CHD risk factor intervention study. Knowledge of risk factors (risk knowledge) was fairly satisfactory at baseline, but diet knowledge was poor. Males, the young, and individuals with a lower level of education had less knowledge. Intervention consisted of a 3-year small mass media programme in one community (low-intensity intervention, LII), additional interpersonal intervention to high-risk individuals in the second (high-intensity intervention, HII), and no intervention in the control community (C). In the cohorts, with the baseline survey and the follow-up study 4 years apart, knowledge improved by 8.1% points in males (7.5% in females) in the HII community and by 7.1% (6.5%) in the LII community, compared to 5.5% (4.8%) in the C community (P less than 0.01). Diet knowledge improved more than risk knowledge, and individuals with lower initial scores benefitted most. Female scored highest. Educational level made a modest positive contribution to knowledge gain, after adjusting for differences in baseline knowledge. High-risk individuals did not have better knowledge at baseline, nor did they gain more from the intervention. We conclude that community intervention over a 4 year period, based on community diagnosis and tailored to the community's needs, can improve health knowledge.

Adolescent↗
PubMed1991

The aqueductus vestibuli--a morphological study.

The morphology of the aqueductus vestibuli enjoys considerable attention as it may possibly play a role in the cause of Ménière's disease. In this study, silicone rubber casts of human temporal bones were used, and the aqueductus vestibuli was then measured by means of a reflection microscope. By this method the morphometry of the aqueductus vestibuli was determined accurately.

Endolymphatic Duct↗