X-linked hypophosphatemia (XLH), the most prevalent form of inherited rickets in humans, is caused by mutations in the PHEX gene, which encodes a protein with high homology to the M13 family of type-II integral membrane zinc metallopeptidases. We created an online mutation database, PHEXdb (http://data.mch.mcgill.ca/phexdb), to catalogue PHEX mutations identified in XLH patients, and found that missense mutations account for 22% of the 157 mutations reported to date. We also undertook to examine the effects of eight missense mutations (C85R, D237G, Y317F, G579R, G579V, S711R, A720T, and F731Y) on synthesis, glycosylation, cellular trafficking, and catalytic activity of the recombinant proteins using several approaches. The wild-type protein was resistant to endoglycosidase H (endo H), indicating that it is fully glycosylated. In addition, biotinylation and immunofluorescence studies revealed that the wild-type protein resides at the cell surface. The D237G, Y317F and F731Y mutant PHEX proteins were also endo H resistant and thus terminally glycosylated. In contrast, endo H digestion demonstrated that C85R, G579R, G579V, S711R and A720T were not terminally glycosylated. Furthermore, immunofluorescence showed that C85R, G579R and S711R were sequestered in the endoplasmic reticulum (ER). A secreted form of wild-type and mutant PHEX (secPHEX) proteins was generated to examine catalytic activity, using a synthetic fluorogenic peptide substrate. For this purpose, rescue of ER-trapped mutant proteins was attempted by growing transfected cells at 26°C. Low temperature was able to rescue three of the five trapped mutant proteins (G579V, S711R and A720T). Residual catalytic activity was observed with four mutant proteins (D237G, Y317F, A720T and F731Y) relative to the wild-type. However, the rescued S711R mutant was devoid of catalytic activity. Finally, limited proteolysis with trypsin and endoproteinase Glu-c revealed that the mutations D237G and F731Y induce conform

This study shows that mice homozygous for the disrupted renal sodium-phosphate (Na+-Pi) cotransporter, Npt2, (Npt2 KO) failed to show an age-dependent decrease in renal Na+-Pi cotransport or an adaptive increase in renal Na+-Pi cotransport in response to dietary Pi restriction. None of the other known renal Na+ -Pi cotransporters could compensate for the loss of Npt2. Additionally, Npt2 gene ablation resulted in a marked decrease in osteoclast number that persisted with age. Although mineral apposition rate was normal at 25- and 115-days of age in Npt2 KO mice, bone formation rate was increased at 115-days of age. These data demonstrate that Npt2 gene expression is necessary for an age-dependent decrease in renal Na+-Pi cotransport and for the renal adaptive response to dietary Pi deprivation, and that Npt2 expression is essential for normal osteoclast function and influences bone formation.

Thèse (de maîtrise)--Université Laval, 2007. / Bibliogr.: f. [108]-112. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thèse (M. Serv. Soc.)--Université Laval, 2003. / Bibliogr.: f. 173-179. Publié aussi en version électronique.

Heart disease is the leading cause of death in the United States. Hyperlipidemia is a predominant risk factor in the development of atherosclerotic cardiovascular disease (ASCVD). The statin drug class is the first line therapeutic for lowering atherogenic low-density lipoprotein (LDL) levels by competitively inhibiting 3-hydroxyl-3methyl-glutaryl-coenzyme A (HMGCR) reductase, the rate-limiting enzyme in cholesterol biosynthesis. However, there are patients who are unable to achieve desirable LDL levels despite statin therapy, such as those with familial hypercholesterolemia or those who are statin intolerant. A new therapy was discovered in 2015 to benefit patients with uncontrolled LDL levels by inhibiting Proprotein convertase subtilisin-kexin type 9 (PCSK9), a key protein in LDL receptor metabolism. Evolocumab (Repatha, AMGEN) is a human monoclonal antibody against human PSCK9. Evolocumab is approved to lower LDL-cholesterol in adult patients who have, despite dietary and lifestyle changes and maximally tolerated statin dose continued suboptimal lipid levels with either ASCVD or Heterozygous Familial Hypercholesterolemia (HeFH). Evolocumab has been shown to significantly reduce atherogenic lipid levels and the recent FOURNIER clinical trial showed that evolocumab reduces cardiovascular events. However, the high annual cost of evolocumab has raised questions as to its cost-effectiveness and role in the prevention and treatment of ASCVD. At the present price levels, this therapy does not appear to be cost-effective with multiple analyses suggesting significant price reduction will be necessary before this drug can be used in standard treatment for secondary prevention of cardiovascular disease in the United States.

Magister Artium (Child and Family Studies) - MA(CFS) / Participation of diverse families in familial needs studies, assist in understanding and comparing their descriptive account of their families and experiences today. This descriptive study compared traditional and non-traditional families of public officials with a focus on (1) form and income, (2) familial needs as per key propositions, (3) families perceptions/experiences at community and broader societal levels and (4) familial needs government must assist them with. The study was contextualized within a contemporary family discourse. It was primarily influenced by a feminist perspective as well as a critique of the nuclear or traditional family grounded in functionalist theory. The public official, as focus, was framed in a human rights and an employee assistance policy discourse influenced by the South African public service context. The study used a quantitative research paradigm, whereby a survey was implemented. The survey was administered to 600 public officials and culminated in a final sample of 70 participants. The study indicated that public officials, as members of families, live in both traditional and non-traditional families. Public officials have familial needs similar to any other family and are also influenced by similar factors in broader society. As both rights holders and duty bearers they can improve their own family lives and also serve families in broader society better. However they too need to be supported with their own family needs. Public officials suggested the areas in which they needed help from the Provincial Government of the Western Cape.

The expression of two phenotypically-contrasting LDL receptor mutations was characterized in cultured fibroblasts from the genetically-homozygous Afrikaner subjects, FH1a and lb, and FH3a and 3b, respectively. Surface receptor expression and functional activity were studied by ligand (¹²⁵I-LDL) and monoclonal antibody (¹²⁵I-IgG-C7) binding, and c35s]-methionine pulse-chase experiments were used to analyze biosynthesis, processing and degradation of IgG-C7- immunoprecipitable mutant receptors. Cells from the "receptor-negative" subjects, FH3a and 3b exhibited reduced, but significant (40-60% of normal) LDL receptor synthesis rates. Newly-synthesized precursors were processed slowly (t½ 1.5 hours versus normal t½ of approximately 15 minutes) to mature receptors which reached the cell-surface, but were rapidly degraded thereafter with a half-life of approximately 1.7 hours (normal value 12.6 hours) thus representing a new type of LDL receptor defect. Lysosomotropic weak bases such as ammonium chloride partially inhibited rapid degradation of the mutant receptors, suggesting the involvement of proteolysis in acidic compartments such as lysosomes or endosomes. Fibroblasts from FH1a and lb exhibited normal synthesis rates of LDL receptor precursors that were processed at a severely reduced rate (t½ approximately 5 hours) to functionally heterogeneous mature surface receptors. Onethird of the receptors (20% of normal levels) bound ¹²⁵I-LDL with normal affinity at 4°C and 37°C, whereas the majority were able to recognize only ¹²⁵I-IgG-C7, and apparently showed defective internalisation and subsequent degradation of the bound IgG-C7 at 37°C. The existence of the two receptor populations was further supported by selective intracellular trapping and degradation of only the active, LDL-binding population, in the presence of ammonium chloride and LOL. The abnormal form predominated even in newly-synthesized receptors and reached a maximum of 50-70% of normal levels after 48 hours of upregulation. Upregulation kinetics and degradation rates (t½ = 10-11 hours) of both functionally-active and abnormal receptor populations were similar to normal. A progressive increase in apparent molecular weight of the slowly-processed precursor receptors suggested a possible role for abnormal glycosylation in the formation of both "normal" and abnormal conformations of the same receptor molecule.

No description available.

No description available.

No description available.