Thesis (Ph. D.)--University of Texas Health Science Center at Houston, School of Public Health, 2007. / Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6419. Advisers: Christopher I. Amos; Ralph F. Frankowski. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 69-76).

Autonomic nervous system (ANS) activity is related to body weight regulation. Based on the hypothesis that Most Obesities kNown Are Low In Sympathetic Activity (MONA LISA), it has been suggested that most obese subjects and animals have low sympathetic nervous system activity. Leptin, leptin receptor, and ghrelin genes influence the ANS regulation of body weight and food intake. The aim of this study was to investigate whether there are differences in leptin, the leptin receptor, or ghrelin regulation between lines of chickens selected for high (HWS) or low body weight (LWS). Intraperitoneal injections of reserpine were administrated to chickens from the HWS and LWS lines. Body weight and food intake were then compared to evaluate ANS regulation. While reserpine caused a transitory decrease in food intake and body weight in both lines, the magnitude of the change was greater in the HWS than in the LWS chickens. However, chickens from the LWS line exhibited greater catecholamine and indoleamine level changes in response to reserpine than those from the HWS line. Therefore, HWS chickens were more sensitive to the body weight-reducing effects of reserpine than LWS lines, while LWS chickens appeared to have greater sympathetic nervous system activity. Food and water intakes were differentially affected in HWS and LWS chickens in response to intracerebroventricular administration of human recombinant leptin. Leptin caused a linear decrease in food intake in the LWS line, but no effect on food intake in the HWS lines. The HWS chickens tended to have reduced water intake following leptin administration. These results suggest that the leptin receptor, or the down-stream neuropeptide regulation pathway mediating the effect of leptin; may be different between chickens from the HWS and LWS lines. Leptin, insulin like growth factor (IGF)-1, and IGF-2 concentrations in the plasma of HWS and LWS lines of chickens were evaluated. Leptin, IGF-1 and IGF-2 levels were significantly higher in the LWS than HWS chickens. The HWS female leptin concentrations were significantly lower than in HWS males or LWS females. Male chickens had greater IGF-1 concentrations in the plasma than female chickens. However, the concentration of IGF-2 did not differ between sexes. The difference in leptin concentrations in these lines and sexes may explain the differences in age of sexual maturity. Different IGF-1 and IGF-2 concentrations may be involved in the obese and anorexic conditions, fast and slow growth, and high and low food consumption found in these two lines of chickens. Differences in the gene sequence of the leptin receptor were observed in HWS and LWS lines of chickens. A single nucleotide polymorphism (SNP) in the intron between exon 8 and 9 introduced a restriction site for the enzyme Sel I in the HWS, but not the LWS line. Two SNP were detected in the leptin receptor cDNA region at nucleotides 189 and 234. At nucleotide 189, the LWS line has both a homozygous (T-T) and heterozygous (C-T), whereas the HWS line has only homozygous (T-T) form. The SNP found in nucleotide 234 introduces a restriction site Mse I in the HWS, but not the LWS line. These specific changes may be directly involved or closely linked to differences between the two lines in either the coding or regulatory domains of the leptin receptor. Differences in the leptin receptor gene expression between HWS and LWS lines of chickens in various organs and ages were observed. Leptin receptor expression in the whole brain was significantly different between sexes at 28 days-of-age in the HWS and LWS lines. The LWS line had higher leptin receptor gene expression in the liver at 2 days-of-age than at 56 and 363 days-of-age, but no differences were observed in the HWS line. In addition, at 2 days-of age, liver leptin receptor gene expression was higher in LWS than HWS chickens, but the reverse was observed at 363 days-of age. In adipose tissue, leptin receptor expression was higher in the LWS than HWS line. Leptin receptor expression in adipose tissue was greater at 363, than 28 and 56 days-of-ages. Our results showed that changes in the regulation of leptin and the leptin receptor were associated with sex, age, and growth. Differences in the ghrelin gene in the HWS and LWS lines under different feeding conditions were investigated. Both HWS and LWS chickens have six extra base pairs in the 5'-untranslated region. The LWS male ghrelin gene expression was significantly lower than in the LWS female and HWS male. The 84 day-old males had lower gene expression than 84 day-old females and 363 day-old males. When comparing different feeding methods, females allowed ad libitum feed consumption had a lower cycle threshold cycle number (CT) ratio than males allowed ad libitum feeding or fasted females. However, the inflection point cycle number of ad libitum fed females was lower than that of the ad libitum fed males, but greater than the fasted females. Ghrelin gene expression was different between the two lines of chickens, and the expression of ghrelin in chickens was influenced by body weight selection, sex, age, and feeding condition. / Ph. D.

Background: The adequacy of serum ascorbic acid (vitamin C) concentrations in young Canadian adults is unknown. Individuals have varied serum ascorbic acid response to dietary vitamin C, possibly due to genetic variation. Objective: To investigate the prevalence of serum ascorbic acid deficiency in young Canadians and to determine whether common genotypes modify the association between dietary vitamin C and serum ascorbic acid. Methods: Subjects were 1277 men and women aged 20-29 years from the Toronto Nutrigenomics and Health study. Vitamin C intakes were estimated by a 196-item FFQ. Fasting blood was collected to measure serum ascorbic acid by HPLC and to genotype for common polymorphisms in genes that code for glutathione S-transferase (GST) (GSTM1, GSTT1 and GSTP1), haptoglobin (Hp), and vitamin C transporters (SLC23A1 and SLC23A2). Results: 53% of subjects had adequate, 33% had suboptimal and 14% had deficient serum ascorbic acid. Subjects with deficiency had higher mean C-reactive protein, waist circumference, BMI and blood pressure than subjects with adequate serum ascorbic acid. The odds ratio (95% confidence interval) for serum ascorbic acid deficiency was 3.43 (2.14, 5.50) for subjects who did not meet the vitamin C recommendation compared to those who did. The corresponding odds ratios were 2.17 (1.10, 4.28) and 12.28 (4.26, 33.42) for individuals with the GSTT1 functional and null genotypes respectively (interaction p=0.01), and 2.29 (0.96, 5.45) and 4.03 (2.01, 8.09) for the GSTM1 functional and null genotypes (interaction p=0.04). These odds ratios were 4.77 (2.36, 9.65) for the Hp2-2 genotype, but 1.69 (0.80, 3.63) for carriers of the Hp1 allele (interaction p=0.02). Serum ascorbic acid concentrations (mean +/- SE) differed among SLC23A1 rs4257763 genotypes (GG: 24.4 +/- 1.3, GA: 26.8 +/- 1.1, AA: 29.7 +/- 1.4, p=0.002). Conclusions: Serum ascorbic acid deficiency is prevalent and associated with markers of chronic disease. Individuals with GST null or Hp2-2 genotypes had an increased risk of deficiency if they did not meet the recommendation for vitamin C, suggesting that GSTs and haptoglobin may spare ascorbic acid when dietary vitamin C is insufficient, thus protecting against serum ascorbic acid deficiency.

Background: The adequacy of serum ascorbic acid (vitamin C) concentrations in young Canadian adults is unknown. Individuals have varied serum ascorbic acid response to dietary vitamin C, possibly due to genetic variation. Objective: To investigate the prevalence of serum ascorbic acid deficiency in young Canadians and to determine whether common genotypes modify the association between dietary vitamin C and serum ascorbic acid. Methods: Subjects were 1277 men and women aged 20-29 years from the Toronto Nutrigenomics and Health study. Vitamin C intakes were estimated by a 196-item FFQ. Fasting blood was collected to measure serum ascorbic acid by HPLC and to genotype for common polymorphisms in genes that code for glutathione S-transferase (GST) (GSTM1, GSTT1 and GSTP1), haptoglobin (Hp), and vitamin C transporters (SLC23A1 and SLC23A2). Results: 53% of subjects had adequate, 33% had suboptimal and 14% had deficient serum ascorbic acid. Subjects with deficiency had higher mean C-reactive protein, waist circumference, BMI and blood pressure than subjects with adequate serum ascorbic acid. The odds ratio (95% confidence interval) for serum ascorbic acid deficiency was 3.43 (2.14, 5.50) for subjects who did not meet the vitamin C recommendation compared to those who did. The corresponding odds ratios were 2.17 (1.10, 4.28) and 12.28 (4.26, 33.42) for individuals with the GSTT1 functional and null genotypes respectively (interaction p=0.01), and 2.29 (0.96, 5.45) and 4.03 (2.01, 8.09) for the GSTM1 functional and null genotypes (interaction p=0.04). These odds ratios were 4.77 (2.36, 9.65) for the Hp2-2 genotype, but 1.69 (0.80, 3.63) for carriers of the Hp1 allele (interaction p=0.02). Serum ascorbic acid concentrations (mean +/- SE) differed among SLC23A1 rs4257763 genotypes (GG: 24.4 +/- 1.3, GA: 26.8 +/- 1.1, AA: 29.7 +/- 1.4, p=0.002). Conclusions: Serum ascorbic acid deficiency is prevalent and associated with markers of chronic disease. Individuals with GST null or Hp2-2 genotypes had an increased risk of deficiency if they did not meet the recommendation for vitamin C, suggesting that GSTs and haptoglobin may spare ascorbic acid when dietary vitamin C is insufficient, thus protecting against serum ascorbic acid deficiency.

Cytochrome P4502E1 (CYP2E1), the ethanol-inducible isoform of cytochrome P450 superfamily, catalyzes many low molecular weight endogenous and exogenous compounds, including ethanol, acetone, drugs like acetaminophen and chlorzoxazone, and industrial solvents like benzene and styrene, most of which are carcinogenic. Besides, it has a high capacity to produce reactive oxygen species. CYP2E1 is induced by ethanol and isoniazid, as well by some pathophysiological conditions like diabetes and starvation. CYP2E1 gene shows genetic polymorphisms which are thought to play a major role in interindividual variability in drug response and in susceptibility to chemical-induced diseases, like several types of cancers. It is well established that CYP2E1 polymorphisms vary markedly in frequency among different ethnic and racial groups. Therefore, in this study, the frequency of two important CYP2E1 polymorphisms / the single nucleotide polymorphisms C-1019T / G-1259C in 5&rsquo / -flanking region and T7678A poymorphism in intron 6, in Turkish population was investigated. For this purpose, whole blood samples were collected from 132 healthy volunteers representing Turkish population and genomic DNA for each subject was isolated in intact form. The genotypes were determined by PCR amplification of corresponding regions followed by restriction endonuclease RsaI, PstI (for C-1019T / G-1259C SNPs) and DraI (for T7678A SNP) digestions. The genotype frequencies, for C-1019T / G-1259C SNPs, which are in complete linkage disequilibrium, were investigated on 116 DNA samples, and determined as 97.4% for homozygous wild type (c1/c1), 2.6% for heterozygotes (c1/c2) and 0.0% for homozygous mutants (c2c2). The allele frequency of wild type allele (c1) was calculated as 98.7% and that of mutated allele (c2) as 1.3%. The genotype frequencies for T7678A SNP, investigated in 108 DNA samples were determined as 80.6% for homozygous wild type (DD), 19.4% for heterozygotes (CD) and 0.0% for homozygous mutants (CC). The corresponding allele frequencies were 90.3% for wild type allele (D), and 9.7% for mutated allele (C). Genotype frequencies of both polymorphisms fit Hardy-Weinberg equation and showed no significant difference with respect to gender. The genotype distributions of both polymorphisms showed similarity when compared to other Caucasian populations like French, Swedish, German, and Italian populations, while both polymorphisms studied differed significantly from Chilean, Japanese, Taiwanese and Chinese populations, as compared with Chi-Square test.

Made available in DSpace on 2014-08-20T13:32:47Z (GMT). No. of bitstreams: 1 dissertacao_lucas_teixeira_hax.pdf: 388762 bytes, checksum: c93c16af033ccd2aa4ff52ec81723de9 (MD5) Previous issue date: 2013-02-27 / The genes of the somatotropic axis, which act regulating the metabolism and physiology of the mammals, present polymorphism associated to some characteristics of economical interest, such as reproductive performance and milk production. Such factors may be influenced by the mutation on only one nucleotide in the base sequence of the gene of the growth hormone receptor (GHR), which may alter the density of GHR on the hepatic tissue. Changes in the coupling of the growth hormone (GH) in the hepatic tissue alter the serum concentration of the insulin-like growth factor 1 (IGF-I), as IGF-I is produced mainly by the liver when it is stimulated by the growth hormone. Different studies have evaluated the effect of polymorphisms in the gene responsible for encoding IGF-I on the reproductive performance and milk production of high production dairy cows. Among other functions, the IGF-I mediates the effects of gonadotropins on the follicular cells, stimulating the growth and differentiation of theca and granulosa follicular cells, playing also a significant role on the final growth and maturation of the dominant follicle. Furthermore, high serum IGF-I concentrations are associated with a earlier return to cyclicity post partum in high yield dairy cows. Thus, the objective of this study was to evaluated the relevance of the mutations in GHR and IGF-I on the calving conception interval, number of inseminations per pregnancy and milk production in Holstein cows. One hundred and fifty five Holstein cows, submitted to a semi extensive management system, subjected to fixed-time artificial insemination (TAI) that got pregnant up to 250 days in milk in 2011, were selected. Among the animals tested, 29% presented GHR AluI (+ / +), 57.5% AluI (+ / -) and 13.5% AluI (- / -) genotype. 34.9% presented IGF-I SnaBI (+ / +), 45.8% SnaBI (+ / -) and 19.3% SnaBI (- / -) genotype. No association was observed between GHR AluI and IGF-I SnaBI genotypes and calving conception interval, number of inseminations per pregnancy and milk yield (P> 0.05). Likewise, there was no association between the interaction of GHR AluI and IGF-I SnaBI genotypes and calving conception interval, number of inseminations per pregnancy and milk yield (P> 0.05). Finally, further studies are necessary to better understand the relevance of GHR AluI and IGF-I SnaBI genotypes to the calving conception interval number of inseminations per pregnancy and milk production in Holstein cows. / Os genes do eixo somatotrópico, que atuam na regulação do metabolismo e fisiologia dos mamíferos, apresentam polimorfismos associados a algumas características de interesse econômico, como desempenho reprodutivo e produção de leite. Tais fatores podem ser influenciados por mutações de apenas um nucleotídeo na sequência de bases do gene do receptor do hormônio do crescimento (GHR), que podem alterar a expressão do GHR no tecido hepático. Mudanças no acoplamento do hormônio do crescimento (GH) no tecido hepático alteram a concentração sérica de fator de crescimento semelhante à insulina tipo1 (IGF-I), visto que o IGF-I tem sua produção endócrina principalmente no fígado mediante estimulação do hormônio do crescimento. Diversos trabalhos têm estudado o efeito de polimorfismos no gene que codifica para IGF-I no desempenho reprodutivo e produção de leite de vacas leiteiras de alta produção. Entre outras funções, o IGF-I atua como mediador dos efeitos das gonadotrofinas nas células foliculares, estimulando o crescimento e diferenciação das células da teca e da granulosa foliculares, apresentando também um importante papel no crescimento final e na maturação do folículo dominante. As altas concentrações sanguíneas de IGF-I estão também associadas a um retorno à ciclicidade mais precoce de vacas leiteiras pós-parto de alta produção. Dessa forma, o objetivo deste estudo foi avaliar a importância de mutações no GHR e IGF-I no desempenho zootécnico, IPC, número de inseminações por prenhez e produção de leite em vacas da raça Holandês. Foram avaliadas 155 vacas da raça Holandês em sistema semi extensivo submetidas à inseminação artificial em tempo fixo (IATF) e que conceberam até 250 dias em lactação no ano de 2011. Entre os animais analisados, 29% apresentaram o genótipo GHR AluI, (+/+), 57,5% AluI (+/-) e 13,5% AluI (-/-). Já para o IGF-I SnaBI 34,9% apresentaram o genótipo IGF-I SnaBI (+/+), 45,8% SnaBI (+/-) e 19,3% SnaBI (-/-). Não foi observada associação entre os genótipos GHR AluI e IGF-I SnaBI e o intervalo parto-concepção, número de inseminações por prenhez e produção de leite (P>0,05). Da mesma forma, não houve associação entre a interação dos genótipos de GHR AluI e IGF-I SnaBI e o intervalo parto-concepção, número de inseminações por prenhez e produção de leite (P>0,05). Finalmente, novos estudos avaliando uma maior população de animais são necessários para elucidar a importância dos genótipos de GHR AluI e IGF-I SnaBI no intervalo parto-concepção, número de inseminações por prenhez e produção de leite.

Les études d'association pangénomiques ont permis d'identifier de nouveaux loci, dont le gène CR1 comme associé au risque de maladie d'Alzheimer (MA). Le récepteur du complément de type 1 (CR1) est une glycoprotéine transmembranaire, présente notamment à la surface des érythrocytes (CR1E), mais également dans le plasma sous forme soluble (CR1s). Le CR1 peut prendre des formes fonctionnelles différentes, qui pourraient conférer des niveaux de risque différents, voire suggérer des mécanismes physiopathologiques de la MA. Si la relation entre CR1 et MA est aujourd'hui connue, son mécanisme reste énigmatique.L'objectif principal de cette thèse était de corréler aux données génétiques (single nucleotide polymorphisms, polymorphismes de longueur, polymorphismes de densité), des éléments phénotypiques acquis comme la densité du CR1E ou le CR1S. D'une part, notre étude a montré grâce à deux méthodes différentes, que la MA était associée à une densité basse de l'isoforme long de CR1 (CR1*2) et suggérait l'existence d'allèle silencieux de CR1. D'autre part, nous avons montré que même si les critères génétiques étaient respectés, certains phénotypes pourraient être acquis au cours de la maladie. Nos résultats suggèrent que la MA résulterait plus d'une insuffisance d'épuration des dépôts amyloïdes, que d'une réponse excessive dont la réaction inflammatoire serait délétère. Bien que cette recherche génotypique et phénotypique, à potentiel physiopathologique, nécessite des investigations à plus grande échelle, elle pourra ouvrir la voie à des nouvelles pistes thérapeutiques qui ne peuvent être envisagées aujourd'hui faute de vue claire du ou des mécanismes en cause. / Genome-wide association studies have identified new loci, including the CR1 gene, as being associated with Alzheimer's disease (AD) risk. The complement receptor type 1 (CR1) is a transmembrane glycoprotein found on the surface of erythrocytes (CR1E), and also in the plasma in soluble form (CR1s). CR1 can have different functional forms that may confer different risk levels, or even suggest pathophysiological mechanisms of AD. Indeed, the relation between CR1 and AD is now well established, the mechanism of this association remains to be elucidated.The main objective of this thesis was to correlate acquired phenotype elements, such as density of CR1E (number of CR1 antigenic sites per erythrocyte) or CR1s with genetic data (single nucleotide polymorphisms, length and density polymorphisms). Firstly, our study showed using two different methods that AD is associated with low density of the long CR1 isoform (CR1*2) and suggested the possible existence of silent CR1 alleles. Secondly, we showed that although genetic criteria were met, some phenotypes could be acquired during the course of the disease. Our findings suggest that AD stems more from insufficient clearance of amyloid deposits than from excessive response whose inflammatory reaction might be deleterious. Although this genetic and phenotypic study with pathophysiological potential still require further investigation on a larger scale, she could pave the way towards new therapeutic avenues that currently remain elusive in the absence of a clear overview of the mechanisms involved.

Hot melt extrusion has attracted recent interest from the pharmaceutical industry and academia as an innovative drug delivery technology. This novel technique has been shown to be a viable and robust method for preparing different drug delivery systems including pellets, implants, tablets, capsules and granules. The aim of this research was to understand hot melt extrusion processing and explore its pharmaceutical applications. Two applications of hot melt extrusion (HME) have been investigated to improve the properties of poorly soluble thermolabile drugs; polymeric solid dispersions and solid state polymorphic transformation. HME is a solvent free, continuous and readily scalable technique which is increasingly being considered as a viable alternative to conventionally used batch techniques. However, the high temperature and shear forces imparted by the extrusion process can limit its applications with heat sensitive active pharmaceutical ingredients (APIs). Artemisinin was selected as a model drug which being thermolabile in nature and possesses processing challenges to processing HME. A low Tg amphiphillic copolymer, Soluplus® was selected as a matrix material. Drug-polymer compatibility was studied using rotational rheometry and thermal characterisation. The drug was found to be completely dissolved within the polymer, although some discolouration of the mixture was observed, indicating degradation of the API. The addition of a small percentage of citric acid to the formulation was found to prevent this degradation by increasing the pH. The dissolution profile of the formulation was approximately five times higher compared to that of the pure drug. The pharmacokinetic study was carried out using Albino rats to calculate bioavailability. The area under plasma concentration time curve (AUC0-24hr) and peak plasma concentration (Cmax) were four times higher for the prepared solid dispersion compared to that of pure artemisinin. Extruded solid dispersions were found to be amorphous in nature and maintained stability for 2 years. A second route to improving the solubility of poorly soluble APIs was also investigated. It was found that under carefully controlled conditions, high temperature extrusion (HTE) could be used to achieve polymorphic transformation with a number of APIs. This solvent-free continuous process was demonstrated with artemisinin, piracetam, carbamazepine and chlorpropamide. Artemisinin was used as a detailed case study of stability, solvent mediated transformation and mechanism of polymrophic transformation during extrusion, using computational modelling and model shear flows. At high temperature, phase transformation from orthorhombic to triclinic crystals was found to occur via the vapour phase. Under mechanical stress the crystalline structure was disrupted, leading to new surfaces being continuously formed and exposed to high temperatures; thus accelerating the transformation process. Polymorphic transformation during HTE was found to comprise three stages; i) preheating and conveying; ii) vapour phase transformation and size reduction and iii) continuous transformation and agglomeration. The triclinic form showed four times greater dissolution rate as compared to the orthorhombic form. The triclinic form showed two fold increase in bioavailability in Albino rats.

Breast cancer affects 1 in 8 women and can be deadly; yet when detected early enough it is often treatable. Thus, early detection of breast cancer is imperative to save lives. The success of early detection depends, in part, on being able to stratify risk. A new approach to determining risk involves identifying genetic variants that alter an individual’s risk for developing breast cancer. This thesis identified key functional candidates involved in breast cancer development, some of which have been verified by other studies. For a few of the functional candidates, further research needs to be done in order to determine the biological significance they play in the development of breast cancer. The functional candidates were identified by comparing SNPs in Linkage Disequilibrium with high risk SNPS—determined by GWAS—using histone modification markers to identify functional genomic elements in breast cell lines. The results yielded three top tier candidates and multiple second tier candidates. Further research should be done in order to assess the risk involved with these variants and the underlying biological mechanism. As genetic testing becomes more accessible to the public, the identification and understanding of these high risk variants will be an essential tool in preventing and treating breast cancer.