Research Articles (Faculty of Science (former Departments))
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- ItemBig Baby, Little Mother: Tsetse Flies Are Exceptions to the Juvenile Small Size Principle(2020-11) Haines, Lee Rafuse; Barreaux, Antoine; Ellstrand, Norman; Vale, Glyn AWhile across the animal kingdom offspring are born smaller than their parents, notable exceptions exist. Several dipteran species belonging to the Hippoboscoidea superfamily can produce offspring larger than themselves. In this essay, the blood-feeding tsetse is focused on. It is suggested that the extreme reproductive strategy of this fly is enabled by feeding solely on highly nutritious blood, and producing larval offspring that are soft and malleable. This immense reproductive expenditure may have evolved to avoid competition with other biting flies. Tsetse also transmit blood-borne parasites that cause the fatal diseases called African trypanosomiases. It is discussed how tsetse life history and reproductive strategy profoundly influence the type of vector control interventions used to reduce fly populations. In closing, it is argued that the unusual life history of tsetse warrants their preservation in the areas where human and animal health is not threatened.
- ItemWeight and health status of black female students(Health & Medical Publishing Group, 2000) Steyn, N. P.; Senekal, M.; Brits, S.; Alberts, M.; Mashego, T.; Nel, J. H.Objective. To examine black female students for the occurrence of risk factors associated with chronic diseases of lifestyle, namely obesity, hypertension, nicotine usage, dyslipidaemia and compromised mental health (depression). Design. A cross-sectional analytical study design was used. All participants were examined within a period of 3 months during 1994. Weight, height, and hip and waist measurements were taken. Body mass index (BMI), waist-hip ratio (WHR) and waist circumference (WC) were calculated for each subject. Two systolic and diastolic blood pressure readings were taken for each participant. Questionnaires were used to determine specific risk factors related to lifestyle. The Beck Depression Inventory (BDI) was used to measure psychological well-being. Fasting blood samples were collected and analysed for serum lipids and iron status. Setting. The University of the North in the Northern Province of South Africa. Subjects. A complete data set of sociodemographic information, anthropometric measurements and blood pressure readings, as well as a psychological health test and a medical questionnaire, were obtained from 231 of the 431 first-year female students who attended the university orientation programme. Only students with a complete data set were included in the sample. Results. Eighteen per cent of students were overweight (BMI 25-29.9), 6.5% were obese (BMI ≥ 30), and 26.8% were underweight. Mean blood pressure, BMI, WHR and WC increased significantly with age and were highest among the ≥ 24-year-olds. Only 1.6% of students had elevated blood pressure, 1.0% smoked and 4.4% took snuff. BMI, WC and WHR were positively correlated with blood pressure and age. Few students had dyslipidaemia (3.8% cholesterol > 5.2 mmol/l). However 14.5% were anaemic (Hb < 11.5 g/dl) and 24.6% had microcytosis (< 80 fl). Nearly one-fifth of students (17.7%) were classified as being moderately to severely depressed. Conclusions. Black female students younger than 24 years exhibited few risk factors associated with chronic diseases of lifestyle. However in older women (≥ 24 years) there were significant increases in BMI, WHR, WC and blood pressure. A large number of students of all ages exhibited moderate to severe depression and anaemia was prevalent.