Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

Insulin resistance is a precursor to type II diabetes mellitus and in conjunction with dyslipidaemia, hypertension, and obesity, these abnormalities constitute the metabolic syndrome. Insulin resistance usually develops before these other diseases and therefore identifying and successfully treating insulin resistant patients may have potentially great preventive value. Insulin resistance, obesity, and subsequently type II diabetes mellitus have increased dramatically and have reached epidemic proportions. The incidence of diabetes, and in particular type II diabetes mellitus, is increasing in developing countries and throughout the world and this is mainly as a result of increasingly sedentary lifestyle and obesity in an aging population. The specific aim of this study was to explore and describe the effect of a 14-week strength-based resistance training programme on insulin resistance amongst individuals aged 25 to 68 years, who are pre-diabetic, have T2DM, and/or are overweight. The research approach used in this investigation was explorative, experimental, and quantitative in nature. The quasi-experimental design consisted of a pre-test and post-test for an experimental and comparison group who were chosen through convenience and snowball sampling. A total of 30 participants were involved in this study, 15 participants in each group. The following dependent variables were selected, namely: body weight; BMI; body composition; waist-to-hip ratio; total cholesterol levels; triglyceride levels; HOMA-IR; and muscle strength for upper and lower body. Pre-and post-test analysis was performed at the Biokinetics and Sport Science Unit, located at the Nelson Mandela Metropolitan University (NMMU). Blood samples of the participants were drawn by nurses at the Health Clinic at the Nelson Mandela Metropolitan University and these blood plasma samples were stored at the Department of Microbiology and Biochemistry at NMMU for later analysis of glucose and insulin. The experimental group trained three times per week for a period of fourteen weeks, performing strength training exercises with progressive increments in the intensity of the exercise. The control group remained sedentary throughout the intervention period. Analysis of the data was conducted utilizing descriptive and inferential statistics. Analysis of variance (ANOVA) was used as a hypothesis-testing procedure to evaluate the mean differences. The following dependent variables showed a decrease in mean values: body weight, body mass index, body fat percentage, waist minimum, cholesterol and insulin. However these differences in results were not practically and statistically significant. The following dependent variables showed an increase in mean values: hip maximum, arm relaxed, arm flexed, thigh circumference, glucose and HOMA-IR. However these results were not practically and statistically significant. The mean differences in the plasma insulin level, pre- to post-test, between both groups indicated that a significant difference (t = -1.77, p = 0.044) existed between them. Cohen‟s d revealed a value of 0.64, which indicates moderate practical significance. The only dependent variable which showed both statistical and practical significance was sum of skinfolds. The findings for sum of skinfolds revealed that the mean differences, from pre- to post-test, between both groups indicated that a significant difference (t = -2.30, p = 0.015) existed between them. Cohen‟s d revealed a value of 0.84, which indicated a large practical significance. Although the sample size was too small to indicate generalisations to the diabetic population as a whole, strength training should be furthermore explored as an alternative and successful modality in the existing range of options available to the health and exercise professional to address the needs of the person with T2DM. The researcher proposed that a bigger sample size be used for the experimental and control group, the intervention period increased as well as various differences related to frequency, intensity and duration of strength training could possibly result in significant changes.

The metabolic disorder diabetes; is a global epidemic affecting people in developed countries and increasingly in developing countries. In two decades time, 350 million people will be diabetic at the current rate of prevalence. In a preliminary study, insulin resistant rats were treated with Prunus Africana (plant A) for 28 days. Plasma samples obtained from P. africana treated rats had increased insulin levels compared to normal and untreated insulin resistant rats (Karachi, 2009). The treatment of insulin resistant rats with P. africana also showed increased glucose uptake in rat adipose tissue (Karachi, 2009), suggesting that P. africana had anti-diabetic properties. The aim of the study was to investigate the mechanism of the anti-diabetic properties of P africana extract. Increased insulin secretion was confirmed by the increased Cpeptide concentration in plasma samples of rats treated with P. africana. In order to explain the high insulin levels, several hypothesis’ were investigated: (1) P. africana may increase insulin secretion in β cells, hence the effect of P. africana on insulin secretion by INS-1 cells was investigated; (2) P. africana may increase insulin secretion by prolonging the half-life of glucagon like peptide-1 (GLP-1) by decreasing dipeptidyl peptidase IV (DPP IV) activity; the effect of P. africana on DPP IV activity was determined spectrophotometrically, (3) P. africana may increase the half-life of insulin in the plasma by decreasing the activity of insulin degrading enzyme (IDE); the effect of P. africana on IDE in rat muscle and spleen samples was investigated. To explain the increased glucose uptake in adipose tissue observed in the previous study two parameters were investigated: (1) increased GLUT4 expression in P. africana treated rats; the effect of P. africana treatment on the expression of glucose transporter 4 (GLUT4) was determined using real-time polymerase chain reaction (RT-PCR), (2) P. africana may increase glucose utilization; the effect of P. africana on glucose utilization was determined in 3T3-L1 cells. The plant extract did not significantly increase insulin secretion by INS-1 cells in the absence of glucose. P. africana decreased DPP IV activity in rat plasma when compared to the untreated insulin resistant rats and this could be a mechanism by which insulin secretion is increased during plant treatment. P. africana decreased IDE activity (however not significantly) when compared to the untreated insulin resistant The effects of a Kenyan antidiabetic plant on insulin homeostasis KY Suleiman VII rats. P. africana appeared to have no effect on GLUT4 expression. The plant appeared to increase glucose utilization in 3T3-L1 cells in the absence of insulin suggesting that P. africana may have insulin like activity. In summary, this study indicates that P. africana is indirectly involved in inhibiting DDPIV. This in turn can increase the half life of GLP-1, which in turn can enhance the secretion of insulin. P. africana increases glucose utilization although there was no evidence that the GLUT 4 transporter has a higher expression in the plant treated rats. Further studies should be conducted to investigate the expression of GLUT1 under the same conditons.

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Motivation: The detrimental effects of obesity and insulin resistance in Caucasians and African-Americans have been the focus of many recent publications, and the association between PAI-1act and markers of the metabolic syndrome is well established but data on African subjects are still lacking. Objectives: To investigate possible differences between the association of PAI-1act with markers of the metabolic syndrome in Caucasian and African women. Methods We used cross-sectional data from the POWIRS I and II studies, involving 95 African and 114 Caucasian women respectively in the Potchefstroom district of the North West Province, South Africa. Results: Mean plasma PAI-1act was significantly higher in the Caucasian than in the African subjects (p < 0.001). Markers for the metabolic syndrome explained 60% of the variance of PAI-1act in the Caucasian group, but only 2.8% of the variance of PAI-1act in the African group. Waist circumference emerged as the strongest independent predictor of PAI-1act in the Caucasian (34%) as well as the African subjects (11%). Conclusion: This study showed clear differences in PAI-1act between African and Caucasian subjects, along with differences in the association of PAI-1act with markers of the metabolic syndrome. Apparent genetic differences between the two groups (especially the role of the 4G/5G genotype) may have an important influence on PAI-1act The role of PAI-1act in the metabolic syndrome may differ between Caucasians and Africans. / Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2005.

Abstract Aim: It has been suggested that chronic hyperinsulinemia from insulin resistance is involved in the etiology of endometrial cancer (EC). We performed a systematic review and meta-analysis to assess whether insulin resistance is associated with the risk of EC. Methods: We searched PubMed-Medline, Embase, Scopus, and Web of Science for articles published from database inception through 30th September 2014. We included all observational studies evaluating components defining insulin resistance in women with and without EC. Quality of the included studies was assessed by NewcastleeOttawa scale. Randomeffects models and inverse variance method were used to meta-analyze the association between insulin resistance components and EC. Results: Twenty-five studies satisfied our inclusion criteria. Fasting insulin levels (13 studies, n Z 4088) were higher in women with EC (mean difference [MD] 33.94 pmol/L, 95% confi- dence interval [CI] 15.04e52.85, p Z 0.0004). No differences were seen in postmenopausal versus pre- and postmenopausal subgroup analysis. Similarly, non-fasting/fasting C-peptide levels (five studies, n Z 1938) were also higher in women with EC (MD 0.14 nmol/L, 95% CI 0.08e0.21, p < 0.00001). Homeostatic model assessment - insulin resistance (HOMA-IR) values (six studies, n Z 1859) in EC patients were significantly higher than in women without EC (MD 1.13, 95% CI 0.20e2.06, p Z 0.02). There was moderate-to-high heterogeneity among the included studies. Conclusion: Currently available epidemiologic evidence is suggestive of significantly higher risk of EC in women with high fasting insulin, non-fasting/fasting C-peptide and HOMAIR values.

by Patricia Jane Anderson. / "June 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 300-328). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

by Lee Suk Kuen Zoe. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 271-314). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstract in Chinese.