published_or_final_version / abstract / toc / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

published_or_final_version / Microbiology / Master / Master of Philosophy

Laboratory scale Cheddar type cheese were made from 411 milk samples originating from Ayrshire, Brown Swiss, Canadienne and Jersey with different phenotypes of kappa-casein (kappa-CN) and beta-lactoglobulin (beta-LG). From the milk input, cheese and whey outputs, the cheese yield, cheese composition and cheesemaking efficiency and other parameters were determined. The overall 37% moisture adjusted cheese yield and cheese yield efficiency were 11.19g, 10.19g, 11.97g, 11.46g and 98.91%, 90.10%, 90.76% and 90.92% for Ayrshire, Brown Swiss, Canadienne and Jersey respectively. The milk of the four respective breeds contained 12.91, 12.69, 13.50, 14.57% total solids; 3.97, 3.58, 4.40, 4.61% fat; 3.61, 3.73, 3.81, 4.00% protein. In Ayrshire, the combination BB/BB and BB/AA (kappa-CN/beta-LG) were associated with higher 37% moisture adjusted cheese yield with the values of 12.51 and 12.83 g/100 g milk respectively. The cheese composition for these two types of milk were 62.28 and 63.96% total solids, 24.22 and 20.40% protein; 32.75 and 37.92% fat. For Brown Swiss, type AA/BB was associated with higher cheese yield (11.18g) with composition of 62.15% total solids, 22.54% protein, 33.23% fat. The phenotype with the highest cheese yield for Canadienne is BB/AB (12.45g) with cheese composition of 63.61% total solids, 23.27% protein and 63.61% fat. In Jersey, the phenotype combination with higher cheese yield (14.59g) is BB/BB. The cheese composition corresponding to this phenotype was 58.64% total solids, 22.96% protein and 29.59% fat. Phenotypes associated with better coagulating properties for Ayrshire, Brown Swiss, Canadienne and Jersey were BB/AB, BB/BB, BB/BB and BB/BB for kappa-CN/beta-LG respectively.

This study was based on the 462 milk samples collected from approximately 2000 cows registered in Dairy Herd Analysis Service (DHAS). Milk samples from fresh milks were phenotyped by gel electrophoresis. Milk samples were selected according to the nine possibilities of phenotype combination of $ kappa$-casein AA, AB, BB and $ beta$-lactoglobulin AA, AB and BB. Selected milk samples from fresh milks were heated at 25$ sp circ$C, 60$ sp circ$C, 70$ sp circ$C, 80$ sp circ$C and 90$ sp circ$C, respectively. Whole casein and whey protein were separated by adjusting the pH to 4.6. Quantitative determination of milk protein were performed by reverse-phase HPLC. Whole casein was separated to $ kappa$-casein ($ kappa$-Cn), $ beta$-casein ($ beta$-Cn) and $ rm alpha sb{s}$-casein ($ rm alpha sb{s}$-Cn). Whey protein was separated as immunoglobulin (Ig), bovine serum albumin (BSA), $ alpha$-lactalbumin ($ alpha$-La) and $ beta$-lactoglobulin ($ beta$-Lg). Individual milk protein fraction was quantitatively determined by relative peak area and their ratios to whey protein or casein. The denaturation of individual milk protein at different heating temperature was investigated. (Abstract shortened by UMI.)

Objective.Humans differ substantially with respect to susceptibility to human immunodeficiency virus type 1 (HIV-1) infection and disease progression. This heterogeneity is attributed to the interplay between the environment, viral diversity, immune response and host genetics. This study focused on host genetics. We studied the association of single nucleotide polymorphisms (SNPs) in peptidyl prolyl isomerase A (PPIA), transportin 3 (TNPO3) and PC4 or SFRS1 interacting protein 1 (PSIP1) genes with HIV-1 infection and disease progression. These genes code for Cyclophilin A (CypA), Transportin-SR2 (TRN-SR2) and Lens epithelium derived growth factor/p75 (LEDGF/p75) proteins respectively, which are all validated HIV replication cofactors in vitro. Methods. One SNP A1650G in the PPIA gene was genotyped in 168 HIV-1 negative and 47 acutely infected individuals using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). 6 intronic and 2 exonic haplotype tagging (ht) SNPs (rs13242262; rs2305325; rs11768572; rs1154330; rs35060568; rs8043; rs6957529; rs10229001) in the TNPO3 gene, 4 intronic ht SNPs (rs2277191, rs1033056, rs12339417 and rs10283923) and 1 exonic SNP (rs61744944, Q472L) in the PSIP1 gene were genotyped in 195 HIV-1 negative and 52 acutely infected individuals using TaqMan assays. The rs1154330, rs2277191, rs12339417 and rs61744944 were further genotyped in 403 chronically infected individuals. CypA and LEDGF/p75 messenger RNA (mRNA) expression levels in peripheral blood mononuclear cells (PBMCs) were quantified by real-time reverse transcriptase polymerase chain reaction (RT-PCR). The impact of the Q472L mutation on the interaction of LEDGF/p75 with HIV-1 integrase (IN) was measured by AlphaScreen. Results. The minor allele (G) of SNP A1650G (1650G) in the promoter region of PPIA was significantly associated with higher viral load (p<0.01), lower CD4+ T cell counts (p<0.01) and showed a possible association with rapid CD4+ T cell decline (p=0.05). The 1650G was further associated with higher CypA expression post HIV-1 infection. The minor allele (G) of rs1154330 in the intron region of TNPO3 was associated with faster HIV-1 acquisition (p<0.01), lower CD4+ T cell counts, higher viral load during primary infection (p<0.05) and rapid CD4+ T cells decline (p<0.01). The minor allele (A) of rs2277191 (rs2277191A) in the intron region of PSIP1 was more frequent among seropositives (p=0.06). Among individuals followed longitudinally, rs2277191A was associated with higher likelihood of HIV-1 acquisition (p=0.08) and rapid CD4+T cell decline (p=0.04) in the recently infected (primary infection) cohort. In contrast, the minor allele (C) of rs12339417 (rs12339417C) also in the intron region of PSIP1 was associated with higher CD4+ T cell counts during primary infection. The rs12339417C was also associated with slower rate of CD4+ T cell decline (p=0.02) and lower mRNA levels of LEDGF/p75 (p<0.01). Seroconverters had higher preinfection mRNA levels of LEDGF/p75 compared to nonseroconverters (p<0.01) and these levels decreased after HIV-1 infection (p=0.02). The Q472L mutation showed approximately 2-fold decrease in the association constant (Kd), suggesting stronger binding to HIV-1 integrase. Our findings demonstrate, for the first time, that genetic polymorphisms in the TNPO3 and PSIP1 genes may be associated with susceptibility to HIV-1 infection and the disease progression. These data provide in vivo evidence that TRN-SR2 and LEDGF/p75 are important host cofactors for HIV-1 replication. This is also the first study to show the association of genetic polymorphisms in the PPIA gene with disease outcome in a population (South African) with high burden of HIV-1 infection. Conclusions. Genetic variation in HIV-1 replication cofactors may be associated with disease outcome in a South African population. These data strongly support the role of these HIV replication cofactors in disease pathogenesis in vivo and suggest that these factors are possible targets for therapeutic interventions. However, these data will need to be replicated in larger cohorts to confirm the effect of these genetic variants. Further studies on how to target these factors in antiviral strategies are needed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Includes 6 reprints of papers by the author / Includes bibliographical references. / 147 leaves + [51] leaves : ill. (some folded) ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Genetics, 1969

Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 79-88). Also avialable via the World Wide Web.

Thesis (M.Res.(Med.))--University of Hong Kong, 2007.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 106-116).