Biomedical subjects

M Steyn

Publications and source records attributed to M Steyn.

At least 19 recordsLinked to original sources

PubMed2006

Interpretation of ante-mortem stature estimates in South Africans.

When human skeletal remains of unknown individuals are analysed, the estimation of ante-mortem stature forms a key part of the report. However, for many people it may be difficult to judge the height of their missing relative in metric values. In this paper, we report on the statures of 2052 black, 483 coloured and 880 white South Africans of both sexes, measured during the last few years. It is shown that the statures of whites are significantly higher than those of the other two groups. The statures of the black and coloured groups are similar. It is proposed that the stature estimates provided in forensic reports are interpreted as tall, medium or short, based on whether they fall in the upper 25%, middle 50% or lower 25% of the distribution for the specific population.

Adolescent↗

PubMed2006

Investigation into the usability of geometric morphometric analysis in assessment of sexual dimorphism.

Understanding sexual dimorphism is very important in studies of human evolution and skeletal biology. Sexual dimorphic characteristics can be studied morphologically and metrically, although morphologic studies pose several problems such as difficulties with quantification and interobserver error. Geometric morphometrics is a relatively new method that allows better assessment of morphologic characteristics. This paper aims to investigate the usability of this method by assessing three different morphologic characteristics in a sample of South African blacks: shape of the greater sciatic notch, mandibular ramus flexure, and shape of the orbits. Relative warps, thin-plate splines, and canonical variates analysis (CVA) analyses were performed. As expected, the shape of the greater sciatic notch provided the best separation between the sexes. Surprisingly, however, the shape of the orbits performed better that ramus flexure. Several possible explanations for this result are possible, which include the possibility that orbit shape is more sexually dimorphic than previously expected, or that biological reality is not reflected by this technique. More research is, however, needed.

Black People↗

PubMed2005

Muti murders form South Africa: a case report.

In Southern Africa, human body parts are sometimes used for medicinal (muti) purposes. The human body is seen as being very powerful. Although ritual killing for this purpose is not common, some cases have been reported. This paper reports on an unusual muti murder, where the remains of two individuals were found in a medicine man's house. Three pots were found, two of which were constructed around human skulls. Various objects, such as coins, bullets, stones, human and animal bones were found inside the pots. They were decorated with beadwork, whistles, skin bangles, etc. Osteological analysis revealed that the human remains probably belonged to a young, white adult male individual, and a juvenile individual of Negroid descent. All associated objects probably have ritual significance, and some of these are discussed.

Age Determination by Skeleton↗

PubMed2005

Metric analysis of sex differences in South African black and white pelves.

Sex determination of unknown skeletal material is one of the most vital determinations made by forensic anthropologists. Numerous studies have focussed on the differences, both osteometric and morphological, between the sexes of a particular racial phenotype and population. Previous work by a variety of researchers has underscored the necessity of population specific standards. The purpose of this research is to metrically assess sex differences in the pelvis of South African whites and blacks and develop standards tailored to these groups. Data were collected from 400 known sex/race skeletons from the Pretoria and Dart Collections. Nine measurements (traditional and newly developed) were taken and subjected to SPSS stepwise and direct discriminant analysis. Results indicated that there are significant differences (p < or = 0.001) between the sexes of both races for most measurements. Discriminant function analysis selected ischial length as the most sexually dimorphic dimension in whites (averaged 86% accuracy), while acetabulum diameter was most diagnostic in blacks (averaged 84% accuracy). Six functions were developed from the pelvic dimensions. Highest accuracy was achieved from Function 1 (including all dimensions) which averaged 95.5% correct classification in whites and 94% in blacks. Functions based on selected parts of the pelvis were not as effective and ranged from 73-86% in whites and 72-84% in blacks. This research provided evidence of the significant sex differences that exist between the pelves of South African whites and blacks whilst measurements used here for discriminant function analysis gave classifications with high accuracies. These results can be used to aid in the identification of human skeletal remains in South Africa.

Anthropometry↗

PubMed2005

Geometric morphometric analysis of mandibular ramus flexure.

Many characteristics of the human skeleton can only be assessed morphologically, which may be problematic due to factors such as interobserver error and difficulties with standardization. Flexure of the mandibular ramus is one of these traits, and various researchers found widely differing results using this morphological feature. The aim of this study was to determine whether differences between male and female mandibular rami could be observed using the computerized method of geometric morphometrics, a valuable tool that helps quantify shape differences. Twenty-eight mandibular rami of black females and 43 of black males were photographed in a standard plane and assessed. It was found that the females were more scattered on the graph (more variable in shape), while the males clustered more around the center point where the two axes met (shape more constant). There was, however, considerable overlap between the sexes. Although different tendencies exist between the rami of males (being more flexed) and females (tending to be straight), the extent of these differences is not adequate to predict the sex of a single individual.

Adult↗

PubMed2005

Assessment of the quality of interaction in distance learning programmes utilising the Internet (WebCT) or interactive television (ITV).

INTRODUCTION: This study focuses on the quality of interaction in interactive TV (ITV), WebCT bulletin boards (BBs) and chat rooms (CRs) and addresses the question of how effectively new collaborative electronic technologies have been married with new pedagogical ideas to create effective learning for distance education students. METHODS: Fifteen (out of 68) BB, 14 (out of 32) CR and 13 (out of 25) ITV conversations were randomly selected for coding using a modified exchange structure analysis. The roles that students and lecturers took in the conversations were determined from this. RESULTS: The percentage of turns made by lecturers as opposed to students was 51% in CRs, 14% in BBs and 68% in ITV. The percentage of turns spent on actual coursework was 73% in CRs, 89% in BBs and 82% in ITV. Comparisons between tutors' and students' roles within as well as between ITV, BBs and CRs were all statistically significant with P < 0.05. In CRs the main roles of both students and lecturers were those of elaborators, inquirers and explainers. In BBs the main roles of students and lecturers were those of explainers and evaluators. In ITV sessions students' main roles were those of elaborators and explainers, whereas lecturers' main roles were those of lecturers, elaborators, inquirers and evaluators. CONCLUSION: In terms of creating a constructivist and active learning community that can operate within a distance learning paradigm, WebCT appears superior to ITV.

Education, Distance↗

PubMed2004

Geometric morphometric analysis of the greater sciatic notch in South Africans.

The width of the greater sciatic notch of the pelvis is a characteristic commonly used to determine sex in unknown individuals. Recent research on South African skeletal material indicated that this feature may not be so reliable, especially in South African white males. In this study the greater sciatic notches of 115 known skeletons of South African origin were analysed using geometric morphometrics. Geometric morphometrics is a relatively new method that helps to quantify shape. Using this method, it was observed that South African black males have the typical narrow shape, while both the black and white females have typical wide notches. The white males, however, showed a very wide variation and their shapes scattered across the range. The shape of the greater sciatic notch is therefore not reliable to use in sex determination in this population group. Geometric morphometric analysis proved to be a valuable and reliable method to verify morphological characteristics observed with more traditional methods.

Adult↗

PubMed2004

Paleoparasitological analysis of coprolites from K2, an Iron Age archaeological site in South Africa: the first finding of Dicrocoelium sp. eggs.

Until now, Dicrocoelium sp. eggs have only been recorded from European and 1 North American archaeological sites. We present evidence for the first record of Dicrocoelium sp. from an African archaeological site. A paleoparasitological study was conducted on 7 coprolite samples from K2, a Late Iron Age site on the farm Greefswald, in the Northern Province of South Africa. Standard parasitological analysis revealed the presence of Dicrocoelium sp. and Trichuris sp. eggs. Today, the parasite does not occur in this region. Trichurid eggs are a relatively common find in paleoparasitological analysis. The presence of Dicrocoelium sp. provides new clues about the antiquity of this parasite, as well as aspects of ancient environment, climate, and interactions among humans, animals, and parasites.

Animals↗

PubMed2004

Assessment of microbial infection risks posed by ingestion of water during domestic water use and full-contact recreation in a mid-southern African region.

A customised Water-related Quantitative Microbial Risk Assessment (WRQMRA) process was used to determine risk of infection to water ingested by users in the south-eastern Free State, South Africa. The WRQMRA consisted of an observed-adverse-effect-level approach (OAELA) and a quantitative microbial risk assessment (QMRA). The OAELA was based on the occurrence of E. coli in the study waters to determine the possible risk of infection and the QMRA probable risk of infection by salmonellae. The WRQMRA was applied to recreational surface resource waters as well as waters from an unprotected spring and waters from the treated municipal supply that were stored in containers for domestic purposes. E. coli numbers were measured against expected infection levels expressed in water quality guidelines, while Salmonella counts were calculated to give the probable infection risk (Pi). Ingestion was based on intake volumes compiled for the various water uses. E. coli occurred in numbers <10(6) in the surface waters, while the untreated spring and treated supply water contained E. coli of <10(2) and <10(1) respectively. Salmonella occurred in numbers of <10(3) in recreational waters, and <10(-1) in water used for domestic purposes. A single exposure to the mean (as well as 95th percentile) risk was calculated using a beta-Poisson dose-response model at ingestion volumes of 100 mL (for full-contact recreation) and 1,318 mL (for domestic water use). Both the OAELA and the QMRA approaches indicated a risk of infection to recreational and domestic water users, even for a single exposure event, with the OAELA either over- or under-estimating the risk of infection for singular exposure events. This indicated that this method, used on its own, could not reliably predict a realistic risk of infection. It is recommended that the full WRQMRA process be used, and further developed to address several uncertainties that became evident during this study.

Drinking↗

PubMed2003

Sexually dimorphic pelvic morphology in South African whites and blacks.

It is well known that there is metric and morphologic variation in the expression of sexual dimorphism between racial phenotypes and populations. Therefore, the purpose of this research is to assess morphologic sex differences in the pelves of South African whites and blacks. Results will be used to improve the identification of human skeletal remains by producing group specific standards. Morphologic features of both left and right os coxae were studied in a sample of 400 known sex/race individuals from the Pretoria and Dart collections. Bones that were clearly pathologic or visibly deformed were excluded from the study. Data were subjected to SPSS analysis. Results indicated that overall, public bone shape was the easiest to assess and was the most consistently reliable morphological indicator of sex in both sexes and population groups. At 88% average accuracy, the most discriminating traits in whites were pubic bone shape and subpubic concavity form. In blacks, greater sciatic notch form allowed the highest separation, averaging 87.5%, followed by pubic shape at 84.5%. Important findings included the fact that there were significant differences in the accuracy of sex determination from pelvic morphology between both males and females and whites and blacks. In conclusion, this study provides quantification of individual morphological traits in the os coxae of white and black South Africans that will be of value in forensic and archaeological analyses, especially when dealing with fragmentary remains. It also demonstrates that population differences affect the expression of sexual dimorphism and must be accounted for to develop the most effective methods of analysis.

Adult↗

PubMed2002

Metric assessment of race from the pelvis in South Africans.

It is well known that there are measurable differences between whites and blacks in the size and proportions of skeletal components. There are also metric differences among populations within these racial phenotypes. The population specific quantification of this variation can be used to aid in the identification of racial affinity in the absence of a more racially definitive skeletal element like the skull. Therefore, the purpose of this research is to quantify these differences in the pelvis of South African whites and blacks. A sample of 400, ostensibly healthy known sex/race os coxae was examined. Skeletal material was obtained from the Pretoria and Dart collections. A series of 13 measurements were taken Data were subjected to SPSS stepwise and direct discriminant function analysis. Pubic length was chosen as best for discriminating between races for males and iliac breadth as best in females. Highest average accuracies (Function 1) were 88% for males (pubic length, greater sciatic notch posterior width, acetabulum diameter, total height) and 85% for females (pubic length, greater sciatic notch posterior width, acetabulum diameter, iliac breath). In conclusion, this research resulted in the development of standards of identification tailored to this population and unquestionably demonstrates that race differences in the skeleton are highly significant and must be considered in all skeletal analyses.

Anthropology, Physical↗

PubMed2002

An assessment of the health status and physical characteristics of an early 20th century community a + Maroelabult in the north west province, South Africa.

As a result of mining activities, two related graveyards dating from the last decade of the 19th century and first half of the 20th century had to be relocated. This provided the opportunity to study 47 skeletons of black South Africans, with the aim of obtaining information on the health status and life style of people from a rural area in a mostly pre-antibiotic era. Although the sample is too small to do a proper palaeodemographic analysis, the age spread of the individuals indicates a high infant mortality rate and generally low life expectancy. Medical services were available, as could be seen from the surgically treated forearm fracture of one individual. One individual had signs of a possible treponemal infection, while subperiosteal bone growth on the ribs of another may indicate tuberculosis. High incidences of arthritic disease and joint degeneration probably indicate a high work load. Enlarged fontanelles with delayed closure were noted in some of the infants. Data on long bone lengths also indicate that the growth of the children may have been retarded in comparison to other similarly aged children. It thus seems as though this was a community under considerable stress. A surprising find was the unusually high incidence of individuals with dental abnormalities and variations.

Adolescent↗

PubMed2001

Long-term homocysteine-lowering treatment with folic acid plus pyridoxine is associated with decreased blood pressure but not with improved brachial artery endothelium-dependent vasodilation or carotid artery stiffness: a 2-year, randomized, placebo-controlled trial.

Homocysteine is associated with atherothrombotic disease, which may be mediated through associations of homocysteine levels with blood pressure, endothelial function, or arterial stiffness. In a placebo-controlled, randomized clinical trial, we measured blood pressure, brachial artery endothelium-dependent vasodilation, and common carotid artery stiffness in 158 clinically healthy siblings of patients with premature atherothrombotic disease at baseline and after 1 and 2 years of homocysteine-lowering treatment with folic acid (5 mg) plus pyridoxine (250 mg). Intention-to-treat analyses limited to participants (n=130) who underwent at least 1 measurement after the baseline visit showed that compared with placebo, treatment with folic acid plus pyridoxine was associated with a 3.7-mm Hg (95% CI -6.8 to -0.6 mm Hg) lower systolic and a 1.9-mm Hg (95% CI -3.7 to -0.02 mm Hg) lower diastolic blood pressure over the 2-year trial period. Together with the decreased occurrence of abnormal exercise electrocardiography tests reported previously, our results support the hypothesis that homocysteine-lowering treatment with folic acid plus pyridoxine has beneficial vascular effects. Because no effects could be demonstrated on brachial artery endothelium-dependent vasodilation or on common carotid artery stiffness, the present study does not support the hypothesis that the cardiovascular effects of homocysteine are mediated through these factors, at least in clinically healthy individuals.

Adult↗

PubMed2000

Change in common carotid artery diameter, distensibility and compliance in subjects with a recent history of impaired glucose tolerance: a 3-year follow-up study.

OBJECTIVE: To assess the development of common carotid artery properties (diameter, distensibility and compliance) in a cohort of 140 subjects (mean age 65.8 years, SD 7.5 years) originally diagnosed as impaired glucose tolerant in a population-based study, and to explore determinants of changes observed. DESIGN: An observational, longitudinal study over a 3-year-period. METHODS: Vessel wall movement detector system based on ultrasonography, linear generalized estimating equations. RESULTS: Carotid artery diameter rose from 6.87-7.02 mm (+ 2.2%, P<0.001). Distensibility decreased from 11.8 to 10.9 x 10-3 kPa-1 (-8.3%, P=0.009). Compliance decreased from 0.44-043 mm2 kPa-1 (P=0.17). Changes in blood pressure level were negatively associated with changes in distensibility and compliance. Baseline fasting glucose levels were positively associated with changes in diameter, while fasting insulin levels were negatively associated with changes in distensibility and compliance in men, but not in women. CONCLUSIONS: In subjects with a recent history of impaired glucose tolerance, we observed an increase in carotid artery diameter and a decrease in distensibility. Change in blood pressure level and baseline fasting glucose and HbA1c levels were positively related to the increase in diameter. In men, but not in women, baseline fasting insulin levels were associated with an acceleration of these changes.

Aged↗

PubMed2000

Traditional healers and cancer prevention.

The increase in the incidence of cancer in South Africa necessitates the expansion of preventative efforts. This study shows that traditional healers in Atteridgeville are consulted by a range of people in their communities, have a basic knowledge of cancer, provide health education to their patients and are willing to participate in cancer preventative strategies. They are therefore ideally suited to augment the services of westernized health care workers. The issue of professionalization is explored and a procedure is suggested whereby the training of traditional healers can be enhanced so as to facilitate their professionalization and their collaboration with other health care workers in the prevention of cancer.

Adult↗

PubMed2000

Age estimation from sternal ends of ribs by phase analysis in South African Blacks.

The sternal ends of ribs are used in age determination of unknown adult remains. Standards for American populations have been described and tested. The method described by Işcan et al. is reviewed and compared with other age markers of the human skeleton. Three hundred and thirty-nine (265 male, 74 female) sternal ends of right fourth ribs, belonging to black individuals deceased in the Gauteng Province of South Africa, were collected during 1994, 1995, and 1996. Three South African investigators applied the existing method and found the repeatability among them acceptable, although the method was less accurate to predict age in this population. New phases with adjusted criteria and age ranges were developed specifically for the South African black population. A tendency toward delayed maturation was found, as well as a diversion of the appearance of female ribs perimenopausally. Future studies involving more individuals in the older age ranges, and females of all ages, could broaden the representativeness of these phases.

Adolescent↗

PubMed1999

Osteometric variation in the humerus: sexual dimorphism in South Africans.

There has been a surge of research on forensic anthropology in South Africa. Differences between the populations of this country and others are demonstrated in many studies. Yet, many forensic osteometric techniques based on other populations are still in use. The purpose of the present study is to develop an osteometric sex determination technique using the humerus. The sample is composed of skeletons of 104 whites and 88 blacks from the Dart and Pretoria collections. Six humeral dimensions were initially analyzed using stepwise discriminant function statistics. Humeral head diameter, deltoid tuberosity circumference and epicondylar breadth were individually calculated in order to make the technique usable for fragmented remains. The results indicated that the head and epicondylar diameters are the best in whites to differentiate sexes from each other, while head diameter and maximum length are best in blacks. Accuracy of correct classification was as high as 96% in whites and 95% in blacks. Crossvalidation provided the same accuracy as the original classification. These accuracy percentages are as high as those expected from the femur and tibia. Posterior probability, which measures the percent affiliation of the sample with its original sex group, was also mostly 80% or better. South African collections are ideal for osteometric analysis, because they are still growing in numbers with cross-sectional representatives from the country.

Adult↗

PubMed1999

Craniometric determination of population affinity in South Africans.

A vital aspect of skeletal analysis is the determination of population affinity of an unknown individual. The aim of this paper is to develop discriminant function formulae to determine race from craniometric dimensions of South African blacks and whites. Skeletons used in this study came from the Universities of the Witwatersrand and Pretoria. The sample is composed of 53 white males and 53 white females and 45 black males and 45 black females. Using 13 standard cranial and 4 mandibular dimensions, average accuracies of 98% were obtained from the crania, which were much more discriminatory than the mandibles (74% males, 87% females). When a "leave-one-out classification" technique was applied to the sample to measure accuracy of multivariate classification, this accuracy was about the same as obtained from the multivariate function. A posterior probability of 0.80 or more was found in as much as 96% of the sample. Stepwise discriminant function formulae for incomplete remains (vault and face) were also derived. Prediction accuracy was considerably lower when North American based formulae were tested on the South Africans, indicating significant craniometric differences between these populations.

Adult↗