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K Steyn

Publications and source records attributed to K Steyn.

84 records · Page 5Linked to original sources
PubMed1987

Haplotype associations of three DNA polymorphisms at the human low density lipoprotein receptor gene locus in familial hypercholesterolaemia.

The frequency and inheritance of three restriction fragment length polymorphisms (RFLPs) of the low density lipoprotein (LDL) receptor gene were investigated in 27 South African families with familial hypercholesterolaemia. Four haplotypes, defined by the enzymes PvuII, StuI, and NcoI, were found to segregate in this population. The frequency of the rare allele detected by NcoI was found to be 0.53 in 45 unrelated familial hypercholesterolaemic (FH) patients compared to 0.33 in 60 normal controls (p less than 0.005). In 71% of the families studied, a haplotype with common alleles for PvuII and StuI and the rare allele for NcoI cosegregated with the defective gene. In 20% of the families, a second haplotype with rare alleles for PvuII and StuI and common allele for NcoI segregated with FH. In these families the haplotypes unambiguously cosegregate with the disease and can therefore be used for early diagnosis of FH.

Adult↗
PubMed1986

Relationship between coronary-prone (type A) behaviour and other coronary risk factors in the coloured population of the Cape Peninsula.

In this investigation, conducted among 976 adult coloureds living in the Cape Peninsula, emphasis was placed on the relationship between type A (coronary-prone) behaviour and a number of other coronary risk factors (hypertension, hypercholesterolaemia, overweight and cigarette smoking), as well as certain demographic variables (age, occupational group and level of education). There was a fairly even distribution between high and low type A behaviour scores for both sexes in the groups aged 15 - 54 years, whereas there were proportionally fewer high than low scores in people between 55 and 64 years old. Housewives generally had lower scores than working women and other women who were not economically active. Both male and female respondents with high type A scores recorded on average higher systolic blood pressure readings. Type A men also smoked more than others. It appears that type A behaviour is mainly independent of other coronary risk factors.

Adolescent↗
PubMed1986

Linkage disequilibrium between a marker on the low-density lipoprotein receptor and high cholesterol levels.

We describe the presence of a linkage disequilibrium between high cholesterol levels in Afrikaner individuals and the common allele of the Pvu II restriction fragment polymorphism on the low-density lipoprotein (LDL) receptor gene. The frequencies of the common and the rare allele in a sample of the Afrikaner population were 0.654 and 0.346 (65 individuals) and 0.794 and 0.206 in the hypercholesterolaemic population (34 patients) (P less than 0.05). This finding supports other evidence for a founder origin of the high frequency of familial hypercholesterolaemia among Afrikaners.

Adolescent↗
PubMed1986

Hypertension in the coloured population of the Cape Peninsula.

In a random sample of 976 coloured people 17.2% of men and 18.4% of women were hypertensive (greater than or equal to 160/95 mmHg or receiving medication). In the same population 35.6% of men and 24.7% of women suffered from total hypertension (greater than or equal to 140/90 mmHg). Men between 25 and 44 years had a markedly higher prevalence of hypertension than women of the same age. Above this age the situation was reversed. Correcting for under- and over-cuffing increased the mean pressures in men and decreased them in older women. Only 42.2% of hypertensive men and 69.9% of women were aware of their condition. Only 41.3% were on medication for it and a mere 16% had blood pressures below 160/95 mmHg. Hypertensives had significantly lower intakes of potassium, calcium, magnesium and saturated fat than normotensive subjects. Young hypertensives consumed more salt than older hypertensives. Both systolic and diastolic blood pressures were positively associated with alcohol consumption, smoking (in men), total serum cholesterol, low-density lipoprotein cholesterol, non-fasting triglyceride and uric acid levels. Hypertensive subjects were less educated and showed more type A coronary-prone behaviour than normotensives. A comparison of the prevalence of hypertension in the four South African ethnic groups is given.

Adolescent↗
PubMed1985

Coronary risk factors in the coloured population of the Cape Peninsula.

A cross-sectional study of risk factors for coronary heart disease (CHD) in a random sample of 976 coloured people revealed a population greatly at risk of CHD. The major reversible risk factors--hypercholesterolaemia, hypertension and smoking--were very common, with 56% of the men and 40% of the women smoking, 18% of both men and women being hypertensive and 17% of both sexes being hypercholesterolaemic. At high cut-off points 62,8% of the men and 59,4% of the women had at least one major reversible risk factor. At lower but real levels of risk, over 80% of the population was affected. Other risk factors such as inactivity, overweight, hyperuricaemia, hypertriglyceridaemia and a positive family history of CHD were all common in this population group. A 'protective' high-density lipoprotein cholesterol level of greater than or equal to 20% of the total serum cholesterol level was found in 74,5% of the men and 81,1% of the women. A comparison with available data on other South African population risk profiles shows marked differences. The need for preventive strategies in the coloured population is clear.

Adolescent↗
PubMed1985

Serum total and high-density lipoprotein cholesterol--reference values obtained in the Coronary Risk Factor Study baseline survey.

Serum total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, and HDL/TC ratios have been established in 7 188 males and females aged 15-64 years who participated in the 1979 Coronary Risk Factor Study (CORIS) baseline survey in the southwestern Cape. TC levels in a sample of 575 1- and 2-year-olds were also determined. TC levels were found to be considerably higher at all ages than corresponding values found in recent surveys in the USA. By fitting epidemiological values associated with a low risk of coronary heart disease (CHD) to the CORIS data, cut-off points (CPs) for 'desirable' TC and HDL levels and HDL/TC ratios were obtained. The CPs for TC are considerably lower than those commonly used by pathology laboratories, and their adoption would result in a greater proportion of the 'westernized' population being regarded as being at risk of CHD, and therefore as requiring diet modification or drug treatment. Experience with the diagnosis of familial hypercholesterolaemia (FH) suggests that the CORIS 80th percentile for TC will correctly identify over 90% of cases of FH. On the basis of this, TC CPs for population screening for FH are also presented.

Adolescent↗
PubMed1984

The prevalence of ischaemic heart disease in three rural South African communities.

In a population reportedly excessively prone to ischaemic heart disease (IHD) i.e. South African (SA) whites, a 3-community study of 7188 subjects aged 15-64 showed a high prevalence of chest pain by questionnaire (9.5% of males, 7.7% of females) or by ECG findings suggestive of IHD (12.8% males, 6.7% females). In the oldest decile (55-64 years) the prevalence of chest pain and/or ECG findings was 33.4% of males and 26.1% of females. For all ages, 18.4% of males and 13.1% of females were apparently affected. Though females were as likely as males to have a history of chest pain they had fewer ECG findings suggestive of IHD and the history was less likely to have been confirmed by a doctor. The significance of individual findings, assessed by the strength of their associations with symptomatic history and age, appeared to differ between the sexes; though very common, medium S-T depression was not classed as suggestive of IHD in females, while left ventricular hypertrophy was unimpressive in males. Large and medium Q waves, large S-T depression, large and medium T wave inversion were positive in both sexes, but left and right bundle branch block only in males. There was little overlap between a history of chest pain and suggestive ECG findings; however, a previous diagnosis of IHD by the family doctor increased the overlap by up to 6 times.

Adolescent↗
PubMedDate not supplied

Factors associated with high density lipoprotein cholesterol in a population with high high density lipoprotein cholesterol levels.

A cross-sectional study of a random sample of 976 coloureds (mixed race) of the Cape Peninsula, ages 15 to 64 years old, revealed a population with unexpectedly high levels of high density lipoprotein (HDL) cholesterol. The mean level for men was 55.4 +/- 16.1 mg/dl (SD) and for women, 60.8 +/- 16.0 mg/dl. The ratio of HDL cholesterol to total cholesterol expressed as a percentage was 26.3% +/- 9.5% for men and 28.1% +/- 9.3% for women. The HDL cholesterol levels were apparently lower than those of black and Negro populations, yet higher than those of Caucasian populations. Men with levels of HDL cholesterol above the median reported a personal history and a family history of coronary heart disease less frequently than did men with lower levels, while women with high levels of HDL cholesterol were less likely to have a history of hypertension or diabetes. Stepwise multiple regression analysis of variables significantly associated with HDL cholesterol levels showed that they explained 29.7% and 24.7%, respectively, of the variation in HDL cholesterol in men and women. Those variables independently associated with HDL cholesterol in both men and women were: serum triglyceride (-), cigarette consumption (-), alcohol, body mass index (-), age, and serum low density lipoprotein cholesterol levels (-). The reasons for the relatively high HDL cholesterol levels in this population are unknown. However, it would seem possible that these levels offer some protection against the high risk factors of smoking, hypertension, and hypercholesterolemia.

Adolescent↗
PubMedDate not supplied

Community-based tobacco control program: the Mamre study, a demonstration project.

OBJECTIVES: To assess the feasibility of a 5-year community-based tobacco control program in the community of Mamre in South Africa, while measuring the smoking and quitting rates at the beginning and end of this demonstration project. METHODS: A tobacco intervention program was developed at low cost in collaboration with the community, and involved a wide range of activities targeting people of all ages, especially those at risk for cardiovascular disease. Community members were trained to deliver smoking cessation programs and specific advice to smokers. Cross-sectional surveys were conducted in 1989 in a random sample of 1238 people, aged 15 years and older, prior to the 5-year demonstration project, and again in 1996 among 974 people at the end of the project. Demographic data and smoking and quitting patterns were collected by interviewer-administered questionnaires. Trained field workers used standardized procedures for recording blood pressure, height, and weight. RESULTS: The community participated with enthusiasm in the activities surrounding smoking cessation and the annual World No Smoking Day. The smoking rate decreased significantly between the two surveys (OR 1996/1989 = 0.82; 95% CI of 0.69-0.99), and the quitting rate increased significantly during the 5-year intervention period compared to the 5 years prior to the baseline survey (OR 1996/1989 = 0.74; 95% CI of 0.57-0.98). Men who participated in the program but continued to use tobacco in 1996 smoked more cigarettes than those who smoked in 1989. People who quit during the intervention period tended to be older, hypertensive, and obese; they consumed no alcohol, and noticed the health warnings posted in the community if they were older and had 10 or more years of education. CONCLUSIONS: A low-cost community-based tobacco control program was successfully implemented in the Mamre community. The program was received enthusiastically, built tobacco cessation skills, and significantly reduced the community's smoking rate compared to that before the demonstration project.

Adolescent↗