Aryl hydroxamic acid analogues as potential therapeutic agents /

A new synthetic pathway to analogues of the aglucones of naturally occurring cyclic hydroxamic acids (2,4-dihydroxy-l,4-benzoxazin-3-ones) has been developed. The new pathway involves the coupling of substituted nitrophenols wdth /-propyl-abromo- O-methoxymethylglycolate. These materials were reductively cyclised to reveal the hydroxamic acid functionality. Removal of the C-2 0-methoxymethyl protecting group was achieved chemoselectively using boron trichloride. The analogue 7-methoxy-2,4-dihydroxy-l,4-benzoxazin-3-one (DIMBOA) was assayed with papain and a semilog plot of activity of papain in the presence of excess DIMBOA was found to be linear. A single exponential equation was suggested as the model for kinetic analysis. '^ Nuclear magnetic resonance (NMR) spectra of a couple of hydroxamates were acquired as reference standards for future mechanistic studies of these compounds as thiol protease inhibitors. A 10% '^-labeled sample ofDIMBOA was also prepared for future mechanistic studies using NMR techniques.

Some aspects of the chemistry of 1, 3, 4 - Thiadiazolium salts and related compounds

The work described in this thesis has been divided into seven sections. The first section involves the preparation of N'-acyl-N'-arylN- benzothiohydrazides by the acylation of N'-aryl-N-benzothiohydrazides and is followed by a brief discussion of their possible conformation in solution. The second section deals with the preparation of 1,3,4-thiadiazolium salts by the action of perchloric acid/acetic anhydride on N'-acylN'- aryl-N-benzothiohydrazides and also by the reaction of N'-arylN- benzothiohydrazides with nitriles in an acidic medium. The preparation of 2-methylthio-I,3,4-thiadiazolium methosulfate by methylating the corresponding thione is also described. The third section deals with the reaction of 2-phenyl- and 2-methyl-I,3,4-thiadiazolium salts with alcohols in the presence of base. The stability and spectra of these compounds are discussed. Treatment of the 2-methyl-I,3,4-thiadiazolium salt with base was found to give rise to a dimeric anhydrobase and evidence supporting its structure is given. The anhydrobase could be trapped by a variety of acylating and thioacylating agents before dimerization occurred. In the fourth section, the reaction of N'-acyl-N'-aryl-N-benzothiohydrazides with a variety of acid anhydrides is described. These compounds were found to be identical with those obtained by acylating the anhydrobase. The mass spectral fragmentation of these compounds is described and the anomolous product obtained upon thiobenzoylation of 3-methyl-l-phenyl-pyrazal-5-one is also discussed. The fifth section deals with thioacyl derivatives of the anhydrobase which were prepared by the action of phosphorus pentasulfide upon the oxygen analogues and also obtained as the major product of the reaction of thioacetic acid with compounds related to N'-aryl-N-benzothiohydrazides. The mass spectra and p.m.r. spectra of these compounds are discussed. In the sixth section, the reaction of the 2-methylthio-l,3,4- thiadiazolium salt with active methylene compounds to give acyl and diacyl derivatives of the anhydrobase is described. Some aspects of these compounds are discussed. The seventh section describes the synthesis of ncyanine~' type dyes incorporating the l,3,4-thiadiazole ring and their spectra are briefly discussed.

Alternative splicing of DNA polymerase beta in vertebrates

Alternative splicing (AS) is the predominant mechanism responsible for increasing eukaryotic transcriptome and proteome complexity. In this phenomenon, numerous mRNA transcripts are produced from a single pre-mRNA sequence. AS is reported to occur in 95% of human multi-exon genes; one specific gene that undergoes AS is DNA polymerase beta (POLB). POLB is the main DNA repair gene which performs short patch base excision repair (BER). In primate untransformed primary fibroblast cell lines, it was determined that the splice variant (SV) frequency of POLB correlates positively with species lifespan. To date, AS patterns of POLB have only been examined in mammals primarily through the use of cell lines. However, little attention has been devoted to investigating if such a relationship exists in non-mammals and whether cell lines reflect what is observed in vertebrate tissues. This idea was explored through cloning and characterization of 1,214 POLB transcripts from four non-mammalian species (Gallus gallus domesticus, Larus glaucescens, Xenopus laevis, and Pogona vitticeps) and two mammalian species (Sylvilagus floridanus and Homo sapiens) in two tissue types, liver and brain. POLB SV frequency occurred at low frequencies, < 3.2%, in non-mammalian tissues relative to mammalian (>20%). The highest POLB SV frequency was found in H. sapiens liver and brain tissues, occurring at 65.4% and 91.7%, respectively. Tissue specific AS of POLB was observed in L. glaucescens, P. vitticeps, and H. sapiens, but not G. gallus domesticus, X. laevis and S. floridanus.The AS patterns of a second gene, transient receptor potential cation channel subfamily V member 1 (TRPV1), were compared to those of POLB in liver and brain tissues of G. gallus domesticus, X. laevis and H. sapiens. This comparison was performed to investigate if any changes (either increase or decrease) observed in the AS of POLB were gene specific or if they were tissue specific, in which case similar changes in AS would be seen in POLB and TRPV1. Analysis did not reveal an increase or decrease in both the AS of POLB and TRPV1 in either the liver or brain tissues of G. gallus domesticus and H. sapiens. This result suggested that the AS patterns of POLB were not influenced by tissue specific rates of AS. Interestingly, an increase in the AS of both genes was only observed in X. laevis brain tissue. This result suggests that AS in general may be increased in the X. laevis brain as compared to liver tissue. No positive correlation between POLB SV frequency and species lifespan was found in non-mammalian tissues. The AS patterns of POLB in human primary untransformed fibroblast cell lines were representative of those seen in human liver tissue but not in brain tissue. Altogether, the AS patterns of POLB from vertebrate tissues and primate cell lines revealed a positive correlation between POLB SV frequency and lifespan in mammals, but not in non-mammals. It appears that this positive correlation does not exist in vertebrate species as a whole.

Using Network Analysis to Understand and Advance Falls Prevention Services and Programs

The purpose of this study was to understand referral linkages that exist among falls prevention agencies in a southern Ontario region using network analysis theory. This was a single case study which included fifteen individual interviews. The data was analyzed through the constant comparative approach. Ten themes emerged and are classified into internal and external factors. Themes associated with internal factors are: 1) health professionals initiating services; 2) communication strategies; 3) formal partnerships; 4) trust; 5) program awareness; and 6) referral policies. Themes associated with external factors are: 1) client characteristics; 2) primary and community care collaboration; 3) networking; and 4) funding. Recommendations to improve the referral pathway are: 1) electronic database; 2) electronic referral forms; 3) educating office staff; and 4) education days. This study outlined the benefit of using network analysis to understand referral pathways and the importance of implementing strategies that will improve falls prevention referral pathways.