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The effects of insulin on milk production were tested employing two different approaches. Firstly, 12 Holstein cows were used to determine the effects of feeding calcium propionate (Ca prop) on dry matter intake (DMI) and production traits. The experimental design was a switchback with 2 treatments (Ca prop at 0 or 300 g/d). The DMI was lower when animals received Ca prop. Ca prop did not affect the yield of milk and its components; however, Ca prop increased protein content. The (acetate+butyrate)/propionate ratio in rumen fluid 2 h after feeding was lower when cows received Ca prop. Plasma insulin concentration was not different between treatments and the putative effect of propionate as an insulin secretagogue was probably related to the maintenance of insulin levels when DMI was lower. In conclusion, Ca prop is a potential feed ingredient to increase protein content in milk. The second approach consisted of intravenous infusion of insulin. A trial was designed to test the effects of insulin, recombinant bovine somatotropin (rbST) and their interaction in lactating dairy cows. Eight Holstein cows were used in a Latin Square design with 4 treatments: (1) intravenous infusion of saline, (2) infusion of saline and administration of 40 mg of rbST per day, (3) intravenous infusion of 12 mg of insulin per day coupled with glucose infusion and (4) rbST administration combined with insulin and glucose infusion. The theory that rbST causes a peripheral resistance to insulin was confirmed. Insulin infusion increased percent protein, percent casein and decreased milk urea content regardless of rbST administration. For milk yield, protein yield, casein yield, lactose percent and lactose yield, there was an interaction between insulin and rbST administration. Similarly, there was an interaction between insulin and rbST on plasma IGF-I levels. Fat yield was higher, with a higher content of long chain fatty acids, during rbST administration, regardless of insulin infusion. I

Motivation: The metabolic syndrome is characterized by a group of risk factors for cardiovascular disease (CVD) that includes obesity, dyslipidemia, high blood pressure, insulin resistance, glucose intolerance or non-insulin dependant diabetes mellitus, pro-thrombotic state and pro-inflammatory state. The NHANES I11 study showed the prevalence of this syndrome to be 24.0% in men and 23.4% in women in the USA. These figures translate to more than 47 million US residents having the metabolic syndrome. In the THUSA (acronym for Transition and Health in the Urbanization of South Africans) study in South Africa it was found that 12% and 28.4% of men and women, respectively, of the black population of the North West Province had three or more disturbances characterizing this syndrome. Therefore, it is evident that the metabolic syndrome is a health problem not only for developed countries but also for developing countries. As a result, this syndrome has been identified as a target for dietary therapies to reduce the risk of CVD and type 2 diabetes. Epidemiological studies have consistently demonstrated an inverse association between nut consumption and coronary heart disease (CHD) morbidity and mortality in different population groups. Nut consumption may not only offer protection against heart disease, but also increase longevity. Recently, the benefits of nuts consumption were acknowledged by the U.S. Food and Drug Administration when they approved a qualified health claim that eating nuts (1.5 ounces/day ≈ 42.8 g/day) may reduce the risk of CHD. In this regard, the most comprehensively studied mechanism involved the favourable lipid lowering effects of nuts. There is, however, a lack of data in the literature regarding the effect of nuts on the metabolic syndrome. Objective: The main objective of this study was to examine the effects of a high walnut diet and a high unsalted cashew nut diet on markers of the metabolic syndrome in humans. In order to provide a foundational body of evidence for the aforementioned, a secondary objective included conducting a systematic review that investigates the effects of nuts on the lipid profile. Methods: The main project consisted of a controlled feeding trial with a parallel, randomized controlled study design on participants having the metabolic syndrome. Sixty-four subjects having this syndrome (29 men, 35 women) with a mean (±SD) age of 45±10 y and who met with the selection criteria were all fed a 3-week run-in control diet. After this period, participants were grouped according to gender and age and then randomized into three groups, namely, those that received a controlled feeding diet including walnuts (20% energy (E), 60-100g/day; protein:carbohydrate:fat=18:42:40%E). or unsalted cashew nuts (20%E 66- 1 15g/day; protein:carbohydrate:fat=l9:44:37%E) or no nuts (protein:carbohydrate:fat=20:47:33%E) for 8 weeks. The participants' physical activity and weight were maintained for the duration of the study. For the systematic review. human intervention trials that investigated the independent effects of nuts on lipid concentrations were included. Medline and Web of Science databases were searched from the start of the database to August 2004 and supplemented by cross-checking reference lists of relevant publications. These papers received a rating based upon the methodology as it appeared in the publication. No formal statistical analysis was performed due to the large differences in study designs of the dietary intervention trials. The main outcome measures for the systematic review, were percentage differences between treatment and control groups for total blood cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDL-C) and triacyglycerols (TG). Results: Regarding the main objective, we found that both the walnut and unsalted cashew nut intervention diets had no significant effect on the lipid profile, serum fructosamine, insulin, insulin sensitivity, insulin resistance, serum high sensitivity C-reactive protein, blood pressure and serum uric acid concentrations when compared to the control dict. All three groups experienced highly significant increases in serum insulin concentrations when comparing the baseline to end (P<0.05). In turn, insulin resistance increased while insulin sensitivity decreased in all three groups. Plasma glucose concentrations increased significantly in the cashew nut group compared to the control group (P<0.05). By contrast, serum fructosamine was unchanged in the cashew nut group while the control group had significantly increased concentrations of this short-term marker of glycaemic control. The literature search for the systematic review yielded 41 5 publications. After screening, 23 nut studies were included in the review with most of these studies including heart-healthy diets. The majority of the studies were short (4-6 weeks) with only one study lasting 6 months. The number of subjects in most of the studies was sufficient to study the effects on TC and LDL-C but not for HDL-C and TG. The results of three almond (50-100g/day), two peanut (35-68g/day), one pecan nut (72g/day) and four walnut (40-84g/day) studies showed convincing evidence for a lipid lowering effect of TC between 2-1 6% and LDL-C between 2- 19%, when compared to their control diets. Currently, there are indications from inadequately designed intervention studies that hazelnuts (lg/day/kg body weight) and pistachios (20%E) may have a lipid lowering effect. At this stage the evidence for macadamia nuts is less convincing. Furthermore, it is apparent that the components in nuts further reduce TC and LDL-C concentrations beyond the effects predicted by equations based solely on dietary fatty acid profiles. Conclusions: In the controlled feeding trial, subjects displayed no improvement in the markers of the metabolic syndrome after following a walnut or unsalted cashew nut diet compared to a control diet while maintaining body weight (8 weeks). Finally, we suspect that the dramatic increase in insulin resistance may have masked the protective effects of the walnut and cashew nut diets in our subjects with the metabolic syndrome Further research is warranted before a consensus can be reached. From the systematic review it was concluded that the consumption of ≈50-100g (≈1.5-3.5 servings) of nuts five or more times/week as part of a heart-healthy diet with total fat content (high in mono- and /or polyunsaturated fatty acids) of ≈ 35% of energy may significantly decrease TC and LDL-C in normo- and hyperlipidemic individuals. Recommendations: A similar nut controlled feeding trial with some form of calorie restriction, should be done on participants having the metabolic syndrome. Future research should use randomized controlled studies with larger sample sizes and longer duration to investigate the effects of nuts on HDL-C and TG concentrations. Also, studies should investigate the effects on the lipid profile of mixed nuts and those individual nuts not yet considered. In addition, the unique nutrient and non-nutrient composition of nuts requires further research in order to elucidate the possible mechanisms responsible for the LDL-C lowering effect / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2005.

Diet recommendations to achieve target metabolic control for prevention of micro and macrovascular complications have been outlined. Although previous studies in individuals with type 2 diabetes have identified certain factors associated with adherence to diet recommendations, adherence is multi-factorial in nature and includes demographic, biological and psychosocial variables. Our main objective was to identify factors associated With dietary behaviour among individuals with type 2 diabetes attending an out-patient clinic. Furthermore, we attempted to identify factors associated with frequency of seeing the dietitian and stages of change far lower fat intake. Principal hypothesis: those who are younger, female, lower in body mass index (BMI), higher in education level, exposed to a dietitian in the past year, higher in stage of change, having greater nutrition knowledge, greater perception of risk and benefits as well as fewer perceived barriers, would consume less total and saturated fat. (Abstract shortened by UMI.)

The present project investigated the effect of glucose, high dose insulin and normoglycemia (GIN) therapy in patients undergoing coronary revascularization surgery. A reduction in myocardial injury as measured by cardiac troponin I was the primary end point. Cardiac function based on hemodynamics and vasoactive drug requirements as well as clinical outcome were evaluated. Hormones and metabolites and cardiac metabolism were investigated concurrently as potential mechanisms of GIN therapy. The major findings of the present study are that GIN therapy reduced post-operative myocardial injury and myocardial dysfunction leading to a decrease in major complications following coronary artery bypass grafting surgery. The mechanism of the overall improvement in cardiac function and decreased morbidity following CABG with GIN therapy is likely to be multi-factorial, but from the present results, is influenced by improved myocardial metabolism. GIN therapy is thus an effective diet for the ischemic heart.

The incidence of Type 1 diabetes is growing yearly. Worryingly, the aetiology of the disease is inconclusive. What is known is that the total number of affected individuals, as well as the severity and number of associated complications are growing for this chronic disease. With increasing complications due to severity, length of exposure, and poor control, the disease is beginning to consume an increasingly major portion of healthcare costs to the extent that it poses major economic risks in several nations. Research has shown that intensive insulin therapy aimed at certain minimum glycosylated haemoglobin threshold levels reduces the incidence of complications by up to 76% compared to conventional insulin therapy. Moreover, the effects of such intensive therapy regimes over a 6.5y duration persists for at least 10y after, a so called metabolic memory. Thus, early intervention can slow the momentum of complications far more easily than later intervention. Early, safe, intensive therapy protocols offer potential solutions to the growing social and economic effects of diabetes. Since the 1970s, the artificial endocrine pancreas has been heralded as just this type of solution. However, no commercial product currently exists, and ongoing limitations in sensors and pumps have resulted in, at best, modest clinical advantages over conventional methods of insulin administration or multiple daily injection. With high upfront costs, high costs of consumables, significant complexity, and the extensive infrastructure and support required, these systems and devices are only used by 2-15% of individuals with Type 1 diabetes. Clearly, there is an urgent need to address the large majority of the Type 1 diabetes population using conventional glucose measurement and insulin administration. For these individuals, current conventional or intensive therapies are failing to deliver recommended levels of glycaemic control. This research develops an understanding of clinical glycaemic control using conventional insulin administration and glucose measurement techniques in Type 1 diabetes based on a clinically validated in silico virtual patient simulation. Based on this understanding, a control protocol for Type 1 diabetes that is relatively simple and clinically practical is developed. The protocol design incorporates physiological modelling and engineering techniques to adapt to individual patient clinical requirements. By doing so, it produces accurate, patient-specific recommendations for insulin interventions. Initially, a simple, physiological compartmental model for the pharmacokinetics of subcutaneously injected insulin is developed. While the absorption process itself is subject to significant potential variability, such models enable a real-time estimation of plasma insulin concentration. This information would otherwise be lacking in the clinical environment of outpatient Type 1 diabetes treatment due to the inconvenience, cost, and laboratory turnaround for plasma insulin measurements. Hence, this validated model offers significant opportunity to optimise therapy selection. An in silico virtual patient simulation tool is also developed. A virtual patient cohort is developed on patient data from a representative cohort of the broad diabetes population. The simulation tool is used to develop a robust, adaptive protocol for prandial insulin dosing against a conventional intensive insulin therapy, as well as a controls group representative of the general diabetes population. The effect on glycaemic control of suboptimal and optimal, prandial and basal insulin therapies is also investigated, with results matching clinical expectations. To gauge the robustness of the developed adaptive protocol, a Monte Carlo analysis is performed, incorporating realistic and physiological errors and variability. Due to the relatively infrequent glucose measurement in outpatient Type 1 diabetes, a method for identifying the diurnal cycle in effective insulin sensitivity and modelling it in retrospective patient data is also presented. The method consists of identifying deterministic and stochastic components in the patient effective insulin sensitivity profile. Circadian rhythmicity and sleep-wake phases have profound effects on effective insulin sensitivity. Identification and prediction of this rhythm is of utmost clinical relevance, with the potential for safer and more effective glycaemic control, with less frequent measurement. It is thus a means of further enhancing any robust protocol and making it more clinically practical to implement. Finally, this research presents an entire framework for the realistic, and rapid development and testing of clinical glycaemic control protocols for outpatient Type 1 diabetes. The models and methods developed within this framework allow rapid and physiological identification of time-variant, patient-specific, effective insulin sensitivity profiles. These profiles form the responses of the virtual patient and can be used to develop and robustly test clinical glycaemic control protocols in a broad range of patients. These effective insulin sensitivity profiles are also rich in dynamics, specifically those circadian in nature which can be identified, and used to provide more accurate glycaemic prediction with the potential for safer and more effective control.

Stress induced hyperglycaemia is prevalent in critical care. Since the landmark paper published by Van den Berghe et al. (2001) a great deal of attention has been paid to intensive insulin therapy in an ICU setting to combat the adverse effects of elevated glucose levels and poor glycaemic control. Glycaemic control protocols have been extensively developed, tested and validated within an ICU setting. However, little research has been conducted on the effects of a glycaemic control protocol in a less acute ward setting. There are many additional challenges presented in a ward setting, such as the variation in meals and levels of activity between patients, from day to day and throughout the day. A simple compartment model is used to describe the nature of insulin and glucose metabolism in patients of the Cardiothoracic Ward (CTW). A stochastic model of the fitted insulin sensitivity parameter is generated for this cohort and validated against cohorts of similar characteristics. The stochastic model is then used to run simulations of predictive control on 7 CTW patients, which shows significantly tighter glucose control than what is obtained with regular clinical procedures. However, the rate of severe hypoglycaemia is an unacceptably high 4.2%. The greatest challenge in maintaining tight glycaemic control in such patients is the consumption of meals at irregular times and of inconsistent quantities. Insulin sensitivity was compared to extensive hourly clinical data of 36 ICU patients. From this data a sepsis score of value 0-4 was generated as gold standard marker of sepsis. Comparing the sepsis score to insulin sensitivity found that insulin sensitivity provides a negative predictive diagnostic for sepsis. High insulin sensitivity of greater than Si = 8 x 10⁻⁵ L mU⁻¹ min⁻¹ rules out sepsis for the majority of patient hours and may be determined non-invasively in real-time from glycaemic control protocol data. Low insulin sensitivity is not an effective diagnostic, as it can equally mark the presence of sepsis or other conditions.

Very premature infants often experience high blood sugar levels as a result of incomplete metabolic development, illness, and stress. High blood sugar levels have been associated with a range of worsened outcomes and increased mortality, but debate exists as to whether high blood sugar levels are a cause of, or marker for, these worsened outcomes. Insulin can be used to lower blood sugar levels, but there is no standard protocol for its use in neonates, and the few clinical studies of insulin use in neonatal intensive care are relatively small and/or have resulted in high incidence of dangerously low blood sugar levels. Hence, there is a need for a safe and effective protocol for controlling blood sugar levels to a normal range in order that potential clinical benefits can be successfully studied in this clinical cohort. This thesis adapted a glucose-insulin model successfully used in adult intensive care for the unique physiology and situation of the very premature infant. The model aims to reflect known physiology. As such, sources and disposal of glucose and insulin within the body are examined using both published data and unique data sets from a study here in New Zealand. In addition, the absorption of glucose from milk feeds is examined. This glucose-insulin physiological model is then used alongside statistical forecasting to develop a protocol for selecting an appropriate insulin dose based on targeting of likely outcomes to a specified target normal range. The protocol is tested in silico using virtual trials, and then clinically implemented, with results showing improved performance over current clinical practice and other published studies. In particular, ~77% of blood glucose is observed within the specified target range across the cohort, and there has been no incidence of dangerously low blood glucose levels. This protocol is thus safe and effective, accounting for inter- and intra- patient variability, and thus enabling patient-specific care.

Previous studies reported that noncompliance to diabetes treatment may result in a series of health complications. To further understand patients’ noncompliance to meal plans, a study on meal planning strategy was developed. Through a survey Certified Diabetes Educators determined which meal planning strategies were the most effective in encouraging patients’ compliance to meal plan according to age groups (18 and under, 19 to 49, 50 to 70, and 71 and above) and recency of diagnosis (newly- and non-newly diagnosed) with Type 2 diabetes. Results identified that nutrition labels had the greatest mean rating for effectiveness in age groups 18 and under, 19 to 49, and 50 to 70; and healthy food choices had the greatest mean rating for effectiveness with age group 71 and above. / Department of Family and Consumer Sciences

Motivation: The metabolic syndrome is characterized by a group of risk factors for cardiovascular disease (CVD) that includes obesity, dyslipidemia, high blood pressure, insulin resistance, glucose intolerance or non-insulin dependant diabetes mellitus, pro-thrombotic state and pro-inflammatory state. The NHANES I11 study showed the prevalence of this syndrome to be 24.0% in men and 23.4% in women in the USA. These figures translate to more than 47 million US residents having the metabolic syndrome. In the THUSA (acronym for Transition and Health in the Urbanization of South Africans) study in South Africa it was found that 12% and 28.4% of men and women, respectively, of the black population of the North West Province had three or more disturbances characterizing this syndrome. Therefore, it is evident that the metabolic syndrome is a health problem not only for developed countries but also for developing countries. As a result, this syndrome has been identified as a target for dietary therapies to reduce the risk of CVD and type 2 diabetes. Epidemiological studies have consistently demonstrated an inverse association between nut consumption and coronary heart disease (CHD) morbidity and mortality in different population groups. Nut consumption may not only offer protection against heart disease, but also increase longevity. Recently, the benefits of nuts consumption were acknowledged by the U.S. Food and Drug Administration when they approved a qualified health claim that eating nuts (1.5 ounces/day ≈ 42.8 g/day) may reduce the risk of CHD. In this regard, the most comprehensively studied mechanism involved the favourable lipid lowering effects of nuts. There is, however, a lack of data in the literature regarding the effect of nuts on the metabolic syndrome. Objective: The main objective of this study was to examine the effects of a high walnut diet and a high unsalted cashew nut diet on markers of the metabolic syndrome in humans. In order to provide a foundational body of evidence for the aforementioned, a secondary objective included conducting a systematic review that investigates the effects of nuts on the lipid profile. Methods: The main project consisted of a controlled feeding trial with a parallel, randomized controlled study design on participants having the metabolic syndrome. Sixty-four subjects having this syndrome (29 men, 35 women) with a mean (±SD) age of 45±10 y and who met with the selection criteria were all fed a 3-week run-in control diet. After this period, participants were grouped according to gender and age and then randomized into three groups, namely, those that received a controlled feeding diet including walnuts (20% energy (E), 60-100g/day; protein:carbohydrate:fat=18:42:40%E). or unsalted cashew nuts (20%E 66- 1 15g/day; protein:carbohydrate:fat=l9:44:37%E) or no nuts (protein:carbohydrate:fat=20:47:33%E) for 8 weeks. The participants' physical activity and weight were maintained for the duration of the study. For the systematic review. human intervention trials that investigated the independent effects of nuts on lipid concentrations were included. Medline and Web of Science databases were searched from the start of the database to August 2004 and supplemented by cross-checking reference lists of relevant publications. These papers received a rating based upon the methodology as it appeared in the publication. No formal statistical analysis was performed due to the large differences in study designs of the dietary intervention trials. The main outcome measures for the systematic review, were percentage differences between treatment and control groups for total blood cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDL-C) and triacyglycerols (TG). Results: Regarding the main objective, we found that both the walnut and unsalted cashew nut intervention diets had no significant effect on the lipid profile, serum fructosamine, insulin, insulin sensitivity, insulin resistance, serum high sensitivity C-reactive protein, blood pressure and serum uric acid concentrations when compared to the control dict. All three groups experienced highly significant increases in serum insulin concentrations when comparing the baseline to end (P<0.05). In turn, insulin resistance increased while insulin sensitivity decreased in all three groups. Plasma glucose concentrations increased significantly in the cashew nut group compared to the control group (P<0.05). By contrast, serum fructosamine was unchanged in the cashew nut group while the control group had significantly increased concentrations of this short-term marker of glycaemic control. The literature search for the systematic review yielded 41 5 publications. After screening, 23 nut studies were included in the review with most of these studies including heart-healthy diets. The majority of the studies were short (4-6 weeks) with only one study lasting 6 months. The number of subjects in most of the studies was sufficient to study the effects on TC and LDL-C but not for HDL-C and TG. The results of three almond (50-100g/day), two peanut (35-68g/day), one pecan nut (72g/day) and four walnut (40-84g/day) studies showed convincing evidence for a lipid lowering effect of TC between 2-1 6% and LDL-C between 2- 19%, when compared to their control diets. Currently, there are indications from inadequately designed intervention studies that hazelnuts (lg/day/kg body weight) and pistachios (20%E) may have a lipid lowering effect. At this stage the evidence for macadamia nuts is less convincing. Furthermore, it is apparent that the components in nuts further reduce TC and LDL-C concentrations beyond the effects predicted by equations based solely on dietary fatty acid profiles. Conclusions: In the controlled feeding trial, subjects displayed no improvement in the markers of the metabolic syndrome after following a walnut or unsalted cashew nut diet compared to a control diet while maintaining body weight (8 weeks). Finally, we suspect that the dramatic increase in insulin resistance may have masked the protective effects of the walnut and cashew nut diets in our subjects with the metabolic syndrome Further research is warranted before a consensus can be reached. From the systematic review it was concluded that the consumption of ≈50-100g (≈1.5-3.5 servings) of nuts five or more times/week as part of a heart-healthy diet with total fat content (high in mono- and /or polyunsaturated fatty acids) of ≈ 35% of energy may significantly decrease TC and LDL-C in normo- and hyperlipidemic individuals. Recommendations: A similar nut controlled feeding trial with some form of calorie restriction, should be done on participants having the metabolic syndrome. Future research should use randomized controlled studies with larger sample sizes and longer duration to investigate the effects of nuts on HDL-C and TG concentrations. Also, studies should investigate the effects on the lipid profile of mixed nuts and those individual nuts not yet considered. In addition, the unique nutrient and non-nutrient composition of nuts requires further research in order to elucidate the possible mechanisms responsible for the LDL-C lowering effect / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2005.