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    Insulin resistence in adult type-2 diabetic skeletal muscle : the effects of exercise and dietary-protein induced skeletal mucscle plasticity controlling microvascular blood flow and glucose transport : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Sport and Exercise Science), Massey University, Wellington, New Zealand
    (Massey University, 2019) Peeters, Wouter
    Introduction: Insulin-stimulated skeletal muscle glucose uptake is impaired in Type-2 Diabetes Mellitus (T2DM). Insulin resistance leads to reduced skeletal muscle microvascular function and insulin signalling. The purpose of the thesis was to evaluate and compare the effect of chronic intake of a novel keratin-derived protein (WDP) and whey protein, in conjunction with exercise training, on glucose homeostasis and skeletal muscle glucose uptake in T2DM. Methods: In a randomized, double-blinded clinical trial, thirty-five men and women with T2DM completed a 14-week exercise intervention but were randomly assigned to ingest either post-exercise and evening supplements of 20 g WDP-whey protein blend (WDP, n = 11), whey protein (WHEY, n = 12) or isocaloric maltodextrin (CON, n = 12). Before and after the intervention, fasting HbA1c and glucose clearance rate (GCR) during a hyperinsulinaemic isoglycaemic clamp were measured. Insulin-stimulated skeletal muscle blood flow and volume were measured during the clamps via near -infrared spectroscopy. Muscle from the m. vastus lateralis was harvested prior to and at 1-h into the clamps to determine skeletal muscle insulin signalling proteins. Results: Substantially bigger improvements in WDP compared to WHEY or CON were found for GCR, insulin-stimulated GLUT4 translocation and insulin-stimulated blood flow. Fasting eNOSser1177/eNOS possibly increased in WDP and WHEY compared to CON. Capillarization improved in all groups with unclear differences between groups. Conclusion: WDP-whey blend ingestion during 14 weeks of exercise training improved skeletal muscle plasticity and some processes involved in insulin-stimulated glucose uptake to a greater magnitude compared to whey protein or an exercise-only group in T2DM. WDP protein holds the potential to be an additional therapy to exercise as a treatment in T2DM.
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    Kiwifruit and guar gum modulation of postprandial blood glucose and its cognitive effects : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Psychology at Massey University
    (Massey University, 2015) Edwards, `Haley
    Glucose is the main source of energy for the brain, and blood glucose levels have been shown to have a significant impact on cognitive performance. This thesis research examined the effects of kiwifruit and guar gum (a soluble fiber) on the postprandial blood glucose response, and to what extent glucose manipulation can influence cognitive performance. Twenty healthy participants took part in a within subjects trial, with each individual consuming one of four breakfast diets per week (Weet-Bix, Weet-Bix + Kiwifruit, Weet-Bix + Guar Gum, and Weet- Bix + Kiwifruit + Guar gum). Each breakfast was separated by at least a 1-week washout period. It has been shown that kiwifruit and its interaction with guar gum decreases blood glucose peaks during the postprandial phase, and maintains a glucose level above fasting baseline measures over a 3-hour time period. In the present study there were no main effects of Breakfast Type across the cognitive tasks, or for interactions between Breakfast Type and Testing Time. However, there was a significant effect for time for each task, collapsed across each breakfast. (Time refers to the three points the cognitive tests were administered, one pre-breakfast, and two post-breakfast at 90 and 180 mins). Trends in the blood glucose response data indicated that when blood glucose levels were controlled and maintained (by the kiwifruit and guar gum), performance on some cognitive tasks improved and was largely sustained across the 3-hour time period, although the effects of practice could not be ruled out.
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    Blood glucose levels in cattle in response to different formulations of betamethasone : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Veterinary Science at Massey University
    (Massey University, 1981) Maw, Ni Ni
    Data on lactational and reproductive performances for 1993 and 1994 of dairy cows which calved in autumn or in spring on eight commercial winter milk supply farms around Palmerston North were collected. The eight commercial winter milk supply herds had a calving spread condensed into autumn and spring seasons. There were 7689 calvings recorded involving 3787 cows. The lactational parameters measured were yields of milk fat and milk protein per lactation, and days in milk (DIM) per cow. The mean milk fat production for the autumn calved cows was 206 kg/cow and 166 kg milk protein/cow (372 kg milk solids) per lactation while the spring calved cows produced 199 kg milk fat/cow and 160 kg milk protein/cow (359 kg milk solids) per lactation. The mean lactation length (DIM) for the autumn calved cows was 282 days, while the spring calved cows had a mean lactation length of 258 days (P<0.05). The mean daily milk fat yield averaged across the days in milk was 0.73 kg per cow for the autumn calved cows while the spring calved cows had a mean daily milk fat yield of 0.77 kg/cow (P<0.05). The mean values of milk production in the second and third months of lactation were 18 litres per day and 17 litres per day for the autumn calved cows while spring calved cows produced 22 litres per day during the second month of lactation and 19 litres per day during the third month of lactation respectively. The reproductive parameters measured were calving interval (CI), 4 weeks submission rates (SR), 42 day non-return rates (NNR), services per conception, 4 week calving rates and empty rates. The autumn calved cows had a longer CI than the spring calved cows; 390 days vs 372 days (P<0.05). The autumn calved cows had a lower average 4 weeks SR than the spring calved cows; 71% vs 81% (P<0.05). The autumn calved cows had a lower average 42 day NNR (conception rate) than the spring calved cows; 55% vs 64% (P<0.05). The autumn calved cows had a higher average of services per conception than the spring calved cows; 1.9 vs 1.6 (P<0.05). The autumn calved cows had a lower 4 week calving rate than the spring calved cows; 41% vs 54% (P<0.05). The autumn calved cows had a higher average empty rate than the spring calved cows; 12% vs 10% (P<0.05). These results show that cows which calved in autumn actually produced larger yields of milk fat and milk protein per lactation than those which calved in spring. However, these higher yields were achieved in longer lactations, and the autumn cows produced lower average daily yields than the spring calved cows. The lower daily yields during the second and third months of lactation by the autumn cows, indicated that these cows were on a lower level of feeding at this stage than the spring calved cows. The autumn calved cows had lower values for all aspects of reproductive performance than the spring calved cows. This difference is probably due to, at least partly, to the lower level of feeding in early lactation. These herds are relatively high producing, and therefore it can be deduced that they are generally well managed. Nevertheless the autumn calved cows were fed less well in early lactation than the spring calved cows, causing slightly poorer performances.
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    Standardisation of in vitro carbohydrate digestion methods for predicting the relative glycemic response to foods : a thesis presented in partial fulfilment of the requirements for the degree of doctor of philosophy in the nutritional sciences, Massey University, Palmerston North campus
    (Massey University, 2011) Woolnough, James William
    Global incidence of type II diabetes is driving the need for communication, via foodlabelling, of the likely glycemic effects of foods. In vivo methods for measuring the glycemic response are costly, time-consuming and hence unsuitable for routine food analysis. In vitro carbohydrate digestion methods offer an alternative to in vivo testing. Foods are incubated sequentially with pepsin and pancreatin under simulated in vivo conditions and the pattern of sugar release used as a predictor of the food’s likely glycemic effect. In vitro methods are well-suited to routine food analysis since they are inexpensive, high-throughput and yield highly precise results. Application of in vitro technology is hindered by the lack of standardised methodology. Countless in vitro methods are described in the literature. All differ in their approach to replicating in vivo conditions. It is not known what effect such differences in methodology might exert on relative estimates of glycemic response. A systematic investigation was undertaken to characterise the relative effect of method variables on subsequent in vitro digestion results, using five standard test foods. Variables investigated include mode of comminution, pepsin inclusion versus omission, amylolytic enzyme concentration, incubatum pH and stirring method. A rudimentary framework for a standardised in vitro method is proposed. Comminution and stirring were the method factors most influential to in vitro starch digestion kinetics. Thus, the standardised method features differing approaches to comminution and incubatum stirring depending on the structural properties of the food to be analysed. In vitro methods, in their current format, do not account for the effect of gastric emptying rate on the glycemic response. The glycemic response and gastric emptying rate of 13C-labelled flatbreads containing either 5, 15 or 30 % fat, known to slow gastric emptying, was measured in ten healthy subjects via a GI test and breath testing. The objective was to obtain in vivo data for gastric emptying that might be applied as a correction to parallel in vitro digests of the flatbreads improving their predictive power. Gastric emptying rate reduced significantly with increased flatbread fat content. There was no difference in the glycemic response to each flatbread. Due to the lack of glycemic effect in vivo, no adjustments to in vitro curves could be made.