Thesis (M. Sc. (Pharmacy)) - Rhodes University, 2007.

Thesis (M.S.W.)--Smith College School for Social Work, Northampton, Mass., 2007. / Typescript. Includes bibliographical references (leaves 62-64).

Thesis (M. Nurs.)--University of Hong Kong, 2006.

No description available.

PAPP-A is a large glycoprotein with alpha2-electrophoretic mobility that is produced by the placenta during pregnancy. In this thesis a biochemical and molecular characterisation of PAPP-A was performed. The polyclonal antiserum (DAKO) directed against PAPP-A has been shown to also interact with proteins other than PAPP-A. These non-specific interactions were abolished by performing Western blotting immunodetection at a high salt concentration (0.6M NaCl). At this salt concentration a single band of 195 kDa was immunodetected and this corresponded to the monomeric PAPP-A molecule. It was also discovered that a subset of paratopes in this antiserum reacted, under the described high salt concentration conditions, with the glycan component of PAPP-A. A placental cDNA library was screened using this antibody for the PAPP-A cDNA but this did not yield a clone for PAPP-A. A possible explanation is that the interaction with this antibody requires carbohydrate components to be present on the PAPP-A molecule. It is known that proteins expressed in bacterial systems are not post-translationally modified. Therefore another approach to the isolation of the PAPP-A cDNA clone was adopted, but this required some primary amino acid sequence of this protein that was unavailable at the time. To generate this information, PAPP-A was purified using its previously unpublished affinity for L-arginine in combination with the already described procedures of ammonium sulphate precipitation, ion exchange and gel filtration. Final purification of PAPP-A was achieved by SDS-PAGE electrophoresis. The isolated monomeric PAPP-A gave a unique single N-terminal amino acid sequence: N-EARGATEEPS. The N terminal sequence combined with the sequence obtained from limited proteolytic digestion of PAPP-A were used to design oligonucleotide primers specific for PAPP-A. These primers were used in a PCR reaction that produced 500 and >1200 bp fragments using the cDNA library as DNA template; thus demonstrating that PAPP-A is synthesised in the placenta. PAPP-A was shown to have O and N-linked carbohydrate chains. Enzymatic deglycosylation demonstrated that the N-linked chains were 8% (w/w) of the molecule. The O-linked groups were extensively modified with the presence of oligomers of N-acetyl-glucosamine. It was also shown that it was these groups the PAPP-A antibodies bind to at high salt concentration. A physical interaction of PAPP-A with endoproteinase Arg-C (EGF-BP) was observed. It was seen that they form a 1:1 (PAPP-A: endoproteinase) sub-unit complex that was stable in SDS. A further investigation revealed that PAPP-A interacted with the endoproteinase Arg-C and this resulted in a 30% inhibition of the esterolytic activity of this enzyme.

Thesis (Ed.M.)--Boston University

Obesity is the most common antenatal comorbidity, affecting one in five of the antenatal population in the UK. It is associated with adverse outcomes for mother and baby in both the short and long term. Increasing data suggest that maternal obesity may programme offspring later life obesity and premature mortality, with high birth weight being a marker for increased risk. The mechanism by which maternal obesity causes excessive neonatal birth weight is incompletely understood but considerable evidence implicates insulin resistance and/or hyperglycaemia. There are currently no effective interventions to mitigate the effects of obesity during pregnancy. In this thesis, we present the findings from a randomised, double blind, placebo controlled trial designed to examine the efficacy of metformin, an insulin-sensitising agent, in obese pregnant women. The aim of the trial was to determine whether giving metformin to obese pregnant women from between 12 and 16 weeks’ gestation until birth, would improve maternal and fetal outcomes. The primary outcome measure was birth weight of the baby, using this as a surrogate marker for the future life risk of the child developing obesity. Nested within this large clinical trial were a series of mechanistic sub-studies. To examine the effect of metformin on maternal insulin resistance at 36 weeks’ gestation, we used the hyperinsulinaemic euglycaemic clamp with concomitant use of stable isotope tracers. This enabled us to characterise in greater detail insulin sensitivity, endogenous glucose production and lipolysis. To determine the effect of metformin on maternal and fetal body composition we used magnetic resonance imaging and spectroscopy. This allowed us to quantify subcutaneous and intra-abdominal adipose tissue deposition and hepatic and skeletal muscle ectopic lipid deposition in the mother; and to measure subcutaneous adipose tissue deposition, hepatic lipid and hepatic volume in the fetus. To determine the effect of metformin on maternal endothelial function, we measured endothelium-dependent flow-mediated dilatation at the beginning and end of pregnancy. Change in diameter of the brachial artery in response to a flow stimulus created by arterial occlusion was measured using ultrasound imaging. We found no significant effect of metformin on birth weight. Mean birth weight was 3463 g (SD 660) in the placebo group and 3462 g (SD 548) in the metformin group (adjusted mean difference in z score –0·029, 95% CI –0·217 to 0·158; p=0·7597). Subjects taking metformin did demonstrate increased insulin sensitivity (M/I difference between means during high dose insulin of 0.02 [95% CI 0.001 to 0.03] milligrams per kilogram fat free mass per minute per pmol/L, p=0.04) but also enhanced endogenous glucose production (difference between means 0.54 [95% CI 0.08 to 1.00] milligrams per kilogram fat free mass per minute, p=0.02), compared with those taking placebo. We did not demonstrate any differences between treatment groups in maternal subcutaneous and intra-abdominal adipose tissue, or ectopic lipid deposition, or in fetal body fat distribution and liver volume. Participants in both treatment groups demonstrated a decline in endothelium-dependent flow-mediated dilatation between early and late pregnancy but there were no differences in the magnitude of that decline between the treatment groups. In conclusion, metformin, administered to obese, non-diabetic pregnant women, does not have any significant effect on birth weight of the baby. Our clamp studies demonstrated that subjects taking metformin were indeed more insulin-sensitive than those taking placebo, but the higher endogenous glucose production in this group suggests a reduced ability to suppress hepatic glucose production in response to insulin. This increased glucose flux may in part explain the lack of effect of metformin on fetal nutrition and growth. We can conclude that metformin, should not be used as an intervention in obese pregnant women to prevent excess birth weight. The global obesity epidemic is one of the greatest public health challenges we face and the cycle of disadvantage continues to be perpetuated to the next generation. The lack of any effective interventions for this high-risk group remains a significant concern and an important area for further research.

Regular physical activity is recommended in healthy pregnancies and has been shown to mitigate adverse pregnancy outcomes. Despite the benefits, many women do not adhere to the recommendations due to concerns of exercise-induced heat stress and the dangers it could pose to the developing fetus. While the majority of the concerns raised are not grounded in evidence, currently there are no studies that directly examine the isolated influence of pregnancy on metabolic heat production resulting from physical activity. Additionally, despite the prevalent use of psycho-physical tools in clinical settings, there is a scarcity of literature exploring the relationship between the physiological and perceptual measures of exercise-induced heat strain in the pregnant population. Therefore, objective one of this thesis was to quantify the heat production resulting from light to moderate physical activity (intensities recommended during pregnancy) throughout gestation. Secondly, in objective two, physiological and perceptual measures of thermal strain were compared and assessed throughout pregnancy. In evaluating the change in heat production resulting from exercise (objective one), 10 non-pregnant control (30±1 yrs; BMI=22.3±0.8 kg/m2) and 10 pregnant (32±1 yrs; pre-pregnancy BMI=22.8±0.8 kg/m2) women performed a seven stage submaximal walking test in a thermal controlled chamber (23ºC). Testing was performed during their 1st (T1, 12-16 wks), 2nd (T2, 24-28 wks) and 3rd (T3, 34-38 wks) trimester of pregnancy while metabolic heat production was measured through indirect calorimetry. To assess the changes in thermal and perceptual strain (objective two), 16 non-pregnant control (32±1 yrs; BMI=22.7±0.7 kg/m2), and 20 pregnant (32±1; pre-pregnancy BMI=23.2±0.6 kg/m2) women underwent a graded walking exercise protocol at T2 and T3. Over the course of this test, heart rate, tympanic temperature (Ttymp), skin temperature (Tskin), rate of perceived exertion (RPE, 20-point scale) and thermal sensation (9-point scale) were assessed. Findings from this thesis show that for the same given progressive exercise test, women in T1 experienced similar metabolic heat production to their non-pregnant counterparts. However, as pregnancy progressed, women exhibited on average, a 7-8% increase in heat production per trimester of pregnancy that can be accounted for by weight gain. Further, at baseline conditions, heart rate responses increased with pregnancy, while Ttymp remained unchanged and Tskin decreased. In response to exercise, the magnitude of change in heart rate, Ttymp and Tskin did not differ between gestational conditions. Finally, a strong correlation was identified between heart rate and RPE throughout pregnancy, while thermal sensation only directly correlated with Ttymp and not Tskin. Overall, the present findings suggest that while the same progressive exercise test results in greater levels of heat production as pregnancy progresses, this is not observed in physiological or perceptual measures of heat strain. Rather, findings of this thesis support the notion of improved thermoregulatory responses to account for the increase in metabolic heat production. Moreover, the present thesis provides support for the use of the RPE and thermal sensation scales as effective psycho-physical tools in the pregnant population under conditions of light to moderate exercise in normothermic conditions.

No description available.

Background: Little is known about long-term pediatric health outcomes following influenza vaccination during pregnancy. Objectives: The objectives of this study were to assess the associations between prenatal exposure to maternal pandemic H1N1 (pH1N1) influenza vaccination and pH1N1 illness, with long-term immune-related pediatric health outcomes. Methods: This retrospective cohort study used a province-wide birth registry from Ontario, individually linked with health administrative databases to ascertain study outcomes over five years of follow-up. Results: We found a weak, but statistically significant, increased association between prenatal pH1N1 influenza vaccination and pediatric asthma, and an inverse association with gastrointestinal infections; otherwise, no other significant associations were observed. Conversely, significant increased associations were observed between pH1N1 influenza illness during pregnancy and all study outcomes. Conclusions: The findings of this study support the safety of influenza vaccination during pregnancy; however more research in this area is required, particularly for seasonal influenza vaccine.