Patients with non-insulin-dependent diabetes mellitus (NIDDM) usually exhibit a marked disturbance of lipid metabolism which is reflected in high levels of plasma total cholesterol, low-density lipoproteins (LDL), and triglycerides, along with low levels of high-density lipoproteins (HDL). Elevated triglycerides are the major contributor to diabetic hyperlipidemia. These plasma lipid concentrations and the fatty acid composition of these lipids are clearly influenced by the type of diet consumed along with the proportion of dietary fatty acids. Therefore, it was the purpose of this investigation to examine the relationships between glycemic control, serum lipid levels of total cholesterol, HDL, LDL and triglycerides to the amounts and types of fats in the typical diets of NIDDM patients as compared to non-diabetic individuals. The dietary fats were also compared with the distribution of fatty acids found in their total lipids and free (in vivo) fatty acids. The relationship between dietary fat intake and serum total lipid levels along with total and free fatty acid distributions was the primary focus.This investigation found that NIDDM subjects have significantly greater triglyceride levels (200 ± 18.4 mg/dL) than non-diabetic controls (93 ± 13.2 mg/dL). Total and LDL cholesterol levels of the NIDDM group were elevated from the control group while HDL levels were depressed, but these differences were of nonsignificant proportions. The NIDDM group typically consumed significantly lowered amounts of teal, saturated, and monounsaturated dietary fatty acids (46.7 ± 7.1 grams, 114.0 ± 2.9 grams, and 16.8 ± 2.5 grams, respectively) compared to the control group (80.0 ± 10.9 grams, 26.7 ± 4.5 grams, and 30.2 ± 4.5 grams, respectively). Even so, the percentage of kilocalories from total fat in the NIDDM vs. the control group diets was not statistically different which may explain the lack of significance between groups with regard to distribution of serum fatty acids. On an individual basis, the types of fat that predominated in the diet were also found in a large percentage in the serum lipid distributions. Positive correlations between saturated fat intake and the blood serum stearic free fatty acid along with polyunsaturated fat intake and linoleic free fatty acid supported this observation. Other investigators (6,62) have reported that dietary intake does indeed contribute to the percentage of fatty acids distributed in the plasma lipids. To determine if a particular dietary fatty acid contributes more significantly to hyperlipidemia, the diet needs to be controlled.On an individualized basis, it was also noted that the diabetics with the lowest amount and percentage of fat in their diets, also had the lowest serum lipid levels. Besides diet, other influential factors which may have contributed to the lipid levels of these NIDDM patients are genetic predisposition, environmental influences, and the stage and progression of each individual's disease. Thus, due to the underlying metabolic impairments which are exacerbated by genetic and/or environmental influences, it is of vital importance to recognize how essential diet manipulation is with regards to lipid control in the treatment of NIDDM patients. / Department of Biology

Cyclin B1 is a cell cycle protein typically associated with the regulation of cellular division (mitosis). Previous studies in this laboratory involving preimplantation mouse embryos found that cyclin B1, or a cyclin B 1-related protein, were present at both G1 and G2/M phase of the cell cycle. Not only was cyclin Bi detected during G1 phase in this study, it was found to be present in higher concentrations at G1 phase through the first three cell cycles. These findings were unexpected, because most of the literature suggests that cyclin B1 is normally degraded during G1 phase. Using immunoprecipitation and immunoblot techniques, a more detailed study of cyclin B1 expression was inititated. Using two different primary antibodies direct against cyclin B1, a 48.97 kDa protein band, which is believed to be cyclin B1, was detected at both G1 and G2/M phases in 1-cell mouse embryos. Using another antibody directed against Cdk1, the kinase that forms a complex with cyclin B1 in order to direct the G2/M transition, a 37 kDa protein band was also detected at both G1 and G2/M phases in 1-cell mouse embryos. In order to determine whether cyclin B1 was present as a complex with Cdk1, immunoblotting with the anti-Cdk1 antibody. Again, a 37kDa protein band was detected at both G1 and G2/M phases. Finally, in order to determine whether the cyclin B1/Cdk1 complex exists in its active form, histone kinase assays were performed using anti-cyclin B1 immunoprecipitates. Kinase activity was detected in immunoprecipitates collected from G2/M phase 1-cell embryos, but no kinase activity was detected from immunoprecipitates collected from G1 phase 1-cell embryos. These data indicate that cyclin B1 and Cdk1 are present and exist as a complex in both G1 and G2/M phases of 1-cell mouse embryos, although the complex only appears to be active at the G2/M phase. / Department of Biology

The logical framework LF and its metalogic Twelf can be used to encode and reason about a wide variety of logics, languages, and other deductive systems in a formal, machine-checkable way. Recent studies have shown that ML-like languages can profitably be extended with a notion of subtyping called refinement types. A refinement type discipline uses an extra layer of term classification above the usual type system to more accurately capture certain properties of terms. I propose that adding refinement types to LF is both useful and practical. To support the claim, I exhibit an extension of LF with refinement types called LFR,work out important details of itsmetatheory, delineate a practical algorithmfor refinement type reconstruction, andpresent several case studies that highlight the utility of refinement types for formalized mathematics. In the end I find that refinement types and LF are a match made in heaven: refinements enable many rich new modes of expression, and the simplicity of LF ensures that they come at a modest cost.

Application of polymer matrix composites in engineering structures has been steadily increasing over the past five decades. Multidirectional polymer composites are one class of continuous fiber reinforced polymer matrix composites used in aerospace structures, where the desired mechanical performance outweighs the cost. Their modulus and strength degrade with time (known as creep and creep rupture) during the service, owing to the viscos-elasticity of the polymer matrix. Additional contribution to this degradation comes from various damage modes developed in the plies of the composite with time and identified in this thesis as TDD (Time Dependent Damage). These damage modes may also develop due to process-induced residual stresses, and during loading to the service load, identified as TID (Time Independent Damage). TID influences the TDD, the creep and the creep rupture. The objective of this thesis is to develop a model to predict the evolution of TID and TDD in multiple plies of a laminate and their influence on creep. The predominant damage mode, transverse cracking, is modeled in this study. The model consists of four modules, PIS, QSL, SL, and VA. The PIS, QSL, and SL moduli predict changes in ply stresses for incremental change in temperature, stress, and time respectively, using lamination theory and assuming linear elastic behavior of the plies during an incremental step. In parallel, each module predicts the stored elastic energy in each ply after each incremental step and compares it with a critical stored elastic energy criterion to determine if a ply would crack. If fracture is predicted, the VA module based on variational analysis, is invoked to determine the crack density and the perturbation in ply stresses due to cracking. The perturbation stresses are used by the module that invoked the VA module to determine the ply stresses after cracking during the current incremental step. The model predictions for a [±45/90]s laminate, at two test temperatures (80C and 180C) and four stresses in the range of 20–54 MPa, compare very well with experimental results validating the model.

In this thesis, a new method has been proposed for calculating the frequencydependent parameters of underground cables. The method uses full wave formulation for calculating the modal electromagnetic fields and corresponding voltages and currents and then extracting frequency-dependent per unit length parameters of underground cables. The proposed method can be used for any cross-sectional shape of cables.

This thesis reports the results of a large number of experiments which were designed to elucidate the mechanisms whereby Gambian children, suffering from acute Plasmodium falciparum malaria may eventually control their infections. These experiments were carried out in vitro and success or failure of the various test systems was judged by their effect on parasite multiplication. Early in the course of these investiqations it was demonstrated that mononuclear cells from these children could cooperate with antibodies present in their serum to bring about a marked reduction in parasite growth. The efficiency of this antibody-dependent cellular cytotoxicity (ADCC) mechanism was related to levels of parasitaemia in the children, being greater in convalescent children than in those with acute malaria. Attempts were now made to identify the effector cells in this ADCC. Purified T and B cells were ineffective and although purified adherent cells (A) had an effect, it was much less than that mediated by the undepleted mononuclear cell population. Adherent cells were, however, fully effective in ADCC if they were exposed to the supernatant from T cells non-specifically activated by PHA. Thus cell cooperation leading to activation appears to play an important role in this system. Finally, experiments were set up to determine whether activated mononuclear cells could exert an inhibitory effect on parasite multiplication which was independent of anti-malarial antibody. It was shown that depression of parasite growth could be achieved by mononuclear cells, either from the children or from Europeans, if these cells were exposed to supernatants of previously stimulated mononuclear cells. These findings can be assembled to provide a tentative model of the development of protective responses in vivo. Perhaps following phagocytosis of parasite antigens and their presentation on the cell surface, T cells become activated: they may cooperate with B cells to produce parasite specific antibodies; they may also activate other mononuclear cells (non T, non B) to become effector cells. These cells, either alone, or perhaps more efficiently in cooperation with antibody, are able to kill parasites by the release of toxic factors, and the infection is brought under control. Finally, large amounts of specific antibodies of appropriate isotypes are synthesized. Acting as opsonins or by activating complement, they may serve to destroy remaining parasites. Their continued presence, by preventing merozoite penetration, may provide at least a temporary defense against reinfection. It is assumed that Gambian adults who have suffered repeated malaria infections and are now immune are defended by their possession of circulating IgG antibodies and B memory cells of all appropriate specificities.

Autoimmune diabetes is a disorder in which the (3-cells in the pancreatic islets of Langerhans are specifically destroyed resulting in absolute insulin deficiency; typically this is a childhood-onset disease, Type 1 Diabetes (T1D). Type 2 Diabetes (T2D) is a metabolic disorder usually developing in adults resulting from defects in insulin secretion and action. Latent Autoimmune Diabetes in Adults (LADA) is a form of diabetes that shares autoimmune disease pathology with T1D but a clinical presentation similar to T2D; LADA patients develop diabetes as adults (>25 years) and do not immediately require insulin treatment for survival. They are therefore often misdiagnosed with T2D. The aims of this work were to characterise immunological and genetic aspects of LADA using a large cohort collected from various patient repositories the United Kingdom to determine if it is a separate disease entity or an age-related extension of T1D. Both T1D and LADA are characterised by autoantibodies to the islet cell protein glutamic acid decarboxylase 65 (GADA) at diagnosis. The persistence and titre of GADA post-diagnosis in LADA was examined at 0.5, 3 and 6 years. GADA persisted in 93% of patients for 6 years; GADA litres decreased between 0.5 and 3 years post-diagnosis and either stabilised or increased again between 3 and 6 years. GADA titre was not associated with age at diagnosis, glycaemic control, β-cell function or other clinical features. GADA titre at 0.5 years was associated with a greater likelihood of requiring more intensive antihyperglycaemic therapy but did not predict therapy or insulin requirement at 3 and 6 years. Autoantibodies against IA-2 plus GADA compared to GADA alone at diagnosis predicted increased therapy requirement by 3 and 6 years and insulin requirement by 3 years postdiagnosis. Variants of the Human Leukocyte Antigen (HLA) genes DRB1 and DQB1, are associated with susceptibility for T1 D. An analysis of these variants in LADA (n = 378) revealed that the predisposing and protective variants in LADA are similar to those reported in T1D; DR3 (in linkage disequilibrium, LD with DQ2) and DR4 (in LD with DQ8) were the main predisposing variants whereas DR2 (in LD with DQ6) was most the protective against LADA. 85% of LADA patients possessed the DR3 and DR4 specificities, compared with 95% seen in T1D, suggesting a reduced predisposition in LADA compared with T1D. Synergistic effects of the DR3 and DR4 specificities occurred in LADA and the DRB1*0401 allele within the DR4 specificity was predisposing to disease, as seen in T1D. No other predisposing variants were identified in LADA. As reported for T1D, DR11, DR13, DQ5, DQ7 and DQ9 were protective against LADA; DQ6 was positively correlated with age at diagnosis. Association analysis of the insulin gene region in LADA (n = 400) showed that the variable number of tandem repeats (VNTR) locus primarily confers susceptibility to disease. Overall, the short Class I alleles predisposed to disease whereas longer Class III alleles conferred dominant protection, as reported in T1D. Fine-structure analysis showed that the Class I haplotypes 'IC+/ID+' and 'ID-' both conferred susceptibility for LADA - unlike in T1D, where the ID- haplotype has been reported to have protective effects. The Class III 'Protective' and Very Protective' haplotypes, conferred equal protection in LADA, as reported forTID. In conclusion; GADA persist post-diagnosis but are not markers for disease progression of LADA. Patterns of susceptibility at the HLA and insulin gene regions in LADA are similar to that reported for T1 D. LADA is likely to represent an age-related extension of T1D rather than a separate disease entity.

Pregestational and gestational diabetes (GDM) places the mother and her offspring at an increased risk for later development of insulin resistance and type 2 diabetes. Oxidative stress may mediate long-term disturbances in glucose homeostasis associated with type 2 diabetes and the metabolic syndrome. This thesis describes a cross-sectional study examining serum concentrations of free radical generated oxysterols as markers of oxidative stress in a cohort of teenage daughters from pregnancies with and without GDM. Daughters of GDM-pregnancies had a tendency of higher levels of serum oxysterols (7beta-hydroxycholesterol); however, this difference was not statistically significant after adjustment for total cholesterol. Serum oxysterols were significantly correlated with obesity measures such as waist circumference and BMI, which likely accounted for the tendency for higher measures of oxysterol concentrations in the GDM daughters. Oxysterols represent potentially important biomarkers for oxidative stress in adolescent girls as their levels track with the metabolic syndrome risk factors. / Le diabète pré-gestationnel et le diabète de gestation (DG) augmentent le risque dedéveloppement d'une future résistance à l'insuline et de diabète de type 2 autant pourla mère que pour l'enfant. Le stress oxydatif est un facteur potentiel impliqué dans ledéséquilibre du glucose sanguin associé au diabète de type 2 et au syndromemétabolique. La présente thèse est une étude sectionnelle croisée, ayant pour but demesurer des marqueurs du stress oxidatif, notamment la concentration des oxystérolsgénérés par les radicaux libres dans le sérum d'adolescentes, nées de mères ayantprésenté ou non un diabète de gestation. Nos résultats montrent des concentrationsd'oxystérols (7P-hydroxycholesterol) plus élevées dans le sérum de filles issues degestations diabétiques à comparer aux filles de mères n'ayant pas eu de DG.Cependant, la différence entre les deux groupes n'était pas statistiquementsignificative après un ajustement au cholestérol total. La concentration d'oxystérolsétait significativement corrélée aux marqueurs d'obésité, notamment la circonférencede la taille et l'index de masse corporelle, possiblement à l'origine de la tendance desoxystérols à être plus élevés dans le cas des adolescentes issues de gestationsdiabétiques.

Although insulin resistance of glucose and fat metabolism in type 2 diabetes mellitus (T2DM) is firmly established, that of protein remains controversial for methodological reasons. A hyperinsulinemic (40MU/m2·min) euglycemic (5.5 mmol/L) isoaminoacidemic (postabsorptive concentrations) clamp was combined with [3-3H]glucose and [1-13C]leucine kinetics to concurrently assess protein and glucose metabolism in 10 hyperglycemic men with T2DM and 11 men without (all BMI=29+/-kg/m2), matched also for age, body composition, and waist circumference. In response to hyperinsulinemia, protein turnover and synthesis were stimulated in controls, but not in T2DM. Both insulin-stimulated total and non-oxidative glucose disposal were diminished in T2DM vs. controls. There was a robust positive correlation between the change in synthesis and glucose disposal. Hence, there is an additive effect of T2DM, beyond that of having excess fat, on insulin resistance of whole body protein turnover and synthesis. Furthermore, protein sensitivity to insulin parallels that of glucose, establishing this as an important concern in T2DM management.

We questioned whether improved glycemic control achieved by oral agent (gliclazide) would correct the altered protein metabolism during an iso-energetic (ISO) and a low energetic (50% of ISO) diets. Seven diabetic (DM) and 7 matched obese control (OB) subjects were give ISO for 14 (DM) or 7 (OB) days, followed by 28 days of the low energetic diet with constant 1.5 g protein/kg BMI$ sb{25}$/d. Giclazide (+ metformin in 4 DM) was given during days 8-14 of ISO and the low energety diet to DM. With ISO and gliclazide, fasting plasma glucose decreased and plasma insulin and nitrogen retention increased while 3-methylhistidine excretion and resting metablic rate decreased to levels no longer different from OB. With moderate energy restriction, weight decreased in all subjects and glycemia normalized in DM. Nitrogen equilibrium was maintained and 3-methylhistidine excretion did not change. The altered protein metabolism observed during hyperglycemia can be improved with oral hypoglycemic agent therapy $ pm$ the low energy diet. Moderate energy restriction with oral hypoglycemic agent therapy achieves diabetes control, nitrogen equilibrium, and a modest decrease in resting metabolic rate.