13 resultados para Alternative Pathway Of Bilirubin Degradation

em Brock University, Canada


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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.

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The general solution behaviour and" the major fragmentation pathways of the anticanceractive PtIV coordination complexes, trans, trans, cis, cis-[PtCIOH{N(pFC6F4) CH2h(pY)2] (1), trans, cis, cis-[Pt(OH)2{N(p-FC6F4)CH2h(Py)2] (2), trans, cis, cis-[Pt(OH)2{N(p-HC6F4)CH2h(Py)2] (3), trans, trans, cis, cis-[PtCIOH{N(pHC6F4) CH2h(Py)2] (4), and trans, trans, cis, cis-[PtOH(OCH3){N(p-HC6F4)CH2h(PY)2] (5) (Py = pyridine) have been deduced by positive-ion tandem-in-time ESI-MS. Overall, the acquired full-scan, positive-ion ESI-MS spectra of 2, 3, and 5 were characterized by the presence of relatively low-intensity [M+Nar and [M+Kt mass spectral peaks, whereas those of 1 and 4 were dominated by extremely intense [M+Hr peaks. Complexes 2 and 3 were also noted to form [2M+Ht and [2M+Nat dilneric cations. The source of Na + and K+ ions is believed to be the sample, the solvent systems used or the transport line carrying the sample solutions into the ES ion source. Further, the fragmentation pathway of all complexes studied was found to be almost identical with concurrent loss of py and H20 molecules, loss of a {N(p-YC6F4)CH2} (Y = F, H) group and/or concomitant release of the latter group and a py ligand being the most conunon. The photochemical degradation behaviour of 1 and 2 was also investigated using either fluorescent or ultraviolet light and some products of that degradation were positively identified. Altogether, light irradiation of solutions of both complexes resulted in cation cationisation, reductive-elimination, ligand-release, ligand-exchange and ligand-addition reactions. Finally, positive- and negative-ion ESI-MSn spectra of 5' -GMP, guanosine, inosine and products of their reactions with 1, 2,3, and 4 were also recorded. On the whole, full-scan ESI-MS spectra of the pure nucleobases revealed the presence of cationic and anionic species that are highly reflective of both their solution ionic composition and their propensity t9 form polymeric clusters. Analyses of mass spectra acquired from their reaction solutions with the aforementioned platinum complexes indicated very slow kinetics. However, all complexes investigated formed, to various degrees, Pt-nucleobase adducts with guanosine and inosine, but not with 5'-GMP. The products included species having coordination numbers of III, IV, V, and VI, among which the first-time· observed, coordinatively saturated, jive-coordinate PtlI-nucleobase complexes were of most interest. The latter complexes are presumably stabilized by 7tback- donation involving the filled d orbitals of the PtII centre and the empty pz· orbital of MeCN. All products, whose peaks appeared inlull-scan ESI-MS spectra, are believed to represent solution species rather than artifacts of gas-phase processes. Finally, negativeion ESI-MSn spectra recorded in reaction solutions of 1 and 4 with guanosine and of the latter complex with inosine revealed the negative-ion-ESI-MS first-time observed, noncovalent, nucleoside-chloride adducts, with the source of chloride anion being complexes 1 and 4 theillselves. In contrast, no such adducts were observed to form with Na25'-GMP or its protonated fonn. Few suggestions are offered for the possible cause(s) behind the absence of such adduct ions.

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DF2, a heptapeptide, is a member of the family of FMRFamide-like peptides and has been shown to increase the amount of transmitter released at neuromuscular junctions of the crayfish, Procambarus clarkit Recent evidence has shown that protein kinase C (PKC), calcium/calmodulin-dependent protein kinase II (CaMKII) and the cAMPdependent protein kinase (PKA) play a role in the neuromodulatory pathway of DF2. The involvement of these kinases led to the prediction that a G-protein-coupled receptor (GPCR) is activated by DF2 due to the role that each kinase plays in traditional GPCR pathways seen in other organisms and in other cells. G-proteins can also act on an enzyme that generates cyclic guanosine monophosphate (cGMP) which mediates its effects through a cGMP-dependent protein kinase (PKG). This thesis addresses the question of whether or not DF2's effects on synaptic transmission in crayfish are mediated by the cyclic nucleotides cAMP and cGMP. The effects of DF2 on synaptic transmission were examined using deep abdominal extensor muscles of the crayfish Procambarus clarkii. An identified motor neuron was stimulated, and excitatory post-synaptic potentials (EPSPs) were recorded in abdominal extensor muscle LI . A number of activators and inhibitors were used to determine whether or not cAMP, PKA, cGMP and PKG mediate the effect of this peptide. Chemicals that are known to activate PKA (Sp-cAMPS) and/or PKG (8-pCPTcGMP) mimic and potentiate DF2's effect by increasing EPSP amplitude. Inhibitors of either PKA (Rp-cAMPS) or PKG (Rp-8-pCPT-cGMPS) block a portion of the increase in EPSP amplitude induced by the peptide. When both kinase inhibitors are applied simultaneously, the entire effect of DF2 on EPSPs is blocked. The PKG inhibitor blocks the effects of a PKG activator but does not alter the effect of a PKA activator on EPSP amplitude. Thus, the PKG inhibitor appears to be relatively specific for PKG. A trend in the data suggests that the PKA inhibitor blocks a portion of the response elicited by the PKG activator. Thus, the PKA inhibitor may be less specific for PKA. Phosphodiesterase inhibitors, which are known to inhibit the breakdown of cAMP (IBMX) and/or cGMP (mdBAMQ), potentiate the effect of the peptide. These results support the hypothesis that cAMP and cGMP, acting through their respective protein kinase enzymes, mediate the ability of DFi to increase transmitter output.

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With the 2010 Vancouver Winter Olympic Games quickly approaching, there has been a heightened interest in the performance of Canadian athletes at international competitions (Duffy, 2007; Fidlin, 2005; Longley, 2006). Two significant documents outline Canada's goal to become the number one sporting nation at the 2010 Olympic Games, and improve Canada's performance at the 2008 Olympic Games: Own the Podium and Road to Excellence (Priestner Allinger & Allinger, 2004; Road to Excellence, 2006). These two documents represent heightened interest in the performance of our elite athletes, in conjunction with Canada's hosting status of the Vancouver 2010 Winter Olympic Games. The requirements to train and compete at the international level have become more demanding both in terms of financial resources and time commitment. The need to financially assist athletes with their training and competition costs has been an important topic of debate over the past decades (Beamish & Borowy, 1987; Gatehouse, 2004; Macintosh, 1996; Munro, 1970; Owens, 2004). Two sources of fiinding for high performance athletes in Canada are the Athlete Assistance Program (AAP) provided by the Federal Government and the Canadian Olympic Excellence Fund provided by the Canadian Olympic Committee. The importance of these fiinds for athletes has been discussed in various forums (Ekos, 1992, 1997, 2005; Priestner Allinger & Allinger, 2004; Thibault «& Babiak, 2005). However, alternative sources of funds for high performance athletes have never been the object of research. As such the purpose of this study was to describe a group of athlete applicants from the time period of November 2004 to April 2006, and to contextualize these applications within the development of the Charitable Fund for Athletes.

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This study examined the effects of providing students with explicit instruction in how to use a repertoire of reading comprehension strategies and test taking skills when reading and responding to three types of questions (direct, inferential, critical). Specifically, the study examined whether providing students with a "model" of how to read and respond to the text and to the comprehension questions improved their reading comprehension relative to providing them with implicit instruction on reading comprehension strategies and test taking skills. Students' reading comprehension and test taking performance scores were compared as a function of instructional condition. Students from 2 grade 8 classes participated in this study. The reading component of the Canadian Achievement Tests, Third Edition (CAT/3) was used to identify students' level of reading comprehension prior to the formal instructional sessions. Students received either explicit instruction, which involved modelling, or implicit instruction, which consisted of review and discussion of the strategies to be used. Comprehension was measured through the administration of formative tests after each instructional session. The formative tests consisted of reading comprehension questions pertaining to a specific form of text (narrative, informational, graphic). In addition, students completed 3 summative tests and a delayed comprehension test which consisted of the alternative version of the CAT/3 standardized reading assessment. These data served as a posttest measure to determine whether students had shown an improvement in their reading comprehension skills as a result of the program delivery. There were significant differences in students' Canadian Achievement Test performance scores prior to the onset of the study. Students in the implicit group attained significantly higher comprehension scores than did students in the explicit group. The results from the program sessions indicated no significant differences in reading comprehension between the implicit and explicit conditions, with the exception of the 6th session involving the reading and interpreting of graphic text. Students in the explicit group performed significantly better when reading and interpreting graphic text than those in the implicit group. No significant differences were evident between the two study conditions across the three summative tests. Upon completion of the study, the results from the Canadian Achievement Test indicated no significant differences in performance between the two study conditions. The findings from this study reveal the effectiveness of providing students with explicit strategy instruction when reading and responding to various forms of text. Modelling the appropriate reading comprehension strategies and test taking skills enabled students to apply the same thought processes to their own independent work. This form of instruction enabled students in the explicit group to improve in their abilities to comprehend and respond to text and therefore should be incorporated as an effective form of classroom teaching.

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The goal of this thesis was to study factors related to the development of Brassica juncea as a sustainable nematicide. Brassica juncea is characterized by the glycoside (glucosinolate) sinigrin. Various methods were developed for the determination of sinigrin in Brassica juncea tissue extracts. Sinigrin concentrations in plant tissues at various stages of growth were monitored. Sinigrin enzymatically breaks down into allylisothiocyanate (AITC). AITC is unstable in aqueous solution and degradation was studied in water and in soil. Finally, the toxicity of AITC against the root-lesion nematode (Pratylenchus penetrans) was determined. A method was developed to extract sinigrin from whole Brassica j uncea tissues. The optimal time of extraction wi th boiling phosphate buffer (0.7mM, pH=6.38) and methanol/water (70:30 v/v) solutions were both 25 minutes. Methanol/water extracted 13% greater amount of sinigrin than phosphate buffer solution. Degradation of sinigrin in boiling phosphate buffer solution (0.13%/minute) was similar to the loss of sinigrin during the extraction procedure. The loss of sinigrin from boiling methanol/water was estimated to be O.Ol%/minute. Brassica juncea extract clean up was accomplished by an ion-pair solid phase extraction (SPE) method. The recovery of sinigrin was 92.6% and coextractive impurities were not detected in the cleaned up extract. Several high performance liquid chromatography (HPLC) methods were developed for the determination of sinigrin. All the developed methods employed an isocratic mobile phase system wi th a low concentration of phosphate buffer solution, ammonium acetate solution or an ion-pair reagent solution. A step gradient system was also developed. The method involved preconditioning the analytical column with phosphate buffer solution and then switching the mobile phase to 100% water after sample injection.Sinigrin and benzyl-glucosinolate were both studied by HPLC particle beam negative chemical ionization mass spectrometry (HPLCPB- NCI-MS). Comparison of the mass spectra revealed the presence of fragments arising from the ~hioglucose moiety and glucosinolate side-chain. Variation in the slnlgrin concentration within Brassica juncea plants was studied (Domo and Cutlass cuItivars). The sinigrin concentration in the top three leaves was studied during growth of each cultivar. For Cutlass, the minimum (200~100~g/g) and maximum (1300~200~g/g) concentrations were observed at the third and seventh week after planting, respectively. For Domo, the minimum (190~70~g/g) and maximum (1100~400~g/g) concentrations were observed at the fourth and eighth week after planting, respectively. The highest sinigrin concentration was observed in flower tissues 2050±90~g/g and 2300±100~g/g for Cutlass and Domo cultivars, respectively. Physical properties of AITC were studied. The solubility of AITC in water was determined to be approximately 1290~g/ml at 24°C. An HPLC method was developed for the separation of degradation compounds from aqueous AITC sample solutions. Some of the degradation compounds identified have not been reported in the literature: allyl-thiourea, allyl-thiocyanate and diallyl-sulfide. In water, AITC degradation to' diallyl-thiourea was favored at basic pH (9.07) and degradation to diallyl-sulfide was favored at acidic pH (4 . 97). It wap necessary to amend the aqueous AITC sample solution with acetonitrile ?efore injection into the HPLC system. The acetonitrile amendment considerably improved AITC recovery and the reproducibility of the results. The half-life of aqueous AITC degradation at room temperature did not follow first-order kinetics. Beginning with a 1084~g/ml solution, the half-life was 633 hours. Wi th an ini tial AITC concentration of 335~g/ml the half-life was 865 hours. At 35°C the half-life AITC was 76+4 hours essentially independent of the iiisolution pH over the range of pH=4.97 to 9.07 (1000~g/ml). AITC degradation was also studied in soil at 35°C; after 24 hours approximately 75% of the initial AITC addition was unrecoverable by water extraction. The ECso of aqueous AITC against the root-lesion nematode (Pratylenchus penetrans) was determined to be approximately 20~g/ml at one hour exposure of the nematode to the test solution. The toxicological study was also performed with a myrosinase treated Brassica juncea extract. Myrosinase treatment of the Brassica juncea extract gave nearly quantitative conversion of sinigrin into AITC. The myrosinase treated extract was of the same efficacy as an aqueous AITC solution of equivalent concentration. The work of this thesis was focused upon understanding parameters relevant to the development of Brassica juncea as a sustainable nematicide. The broad range of experiments were undertaken in support of a research priority at Agriculture and Agri-Food Canada.

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Currently, much of the autism literature supports the notion that Pervasive Developmental Disorder (PDD) is a deviation from what is considered "normal" and, accordingly, that it is in need of early remediation. This thesis explored alternative constructions of autism and pathology by drawing on theorists from other disciplines, such as cultural studies (Deleuze & Guattari, 1987, 1965, 1972, 1975,1980, 2003), critical psychology (Parker, 1995, 2002, 2005, 2007), disability studies (Danforth,1997, 1999, 2000; Skrtic, 1995, 1996) and anti-psychiatry (Basaglia, 1987). In an attempt to show how our accounts of the world encompass constructions rooted in language and our own histories of thinking about topics that interest us, this research took an autoethnographic approach to understanding autism discourse. Instead of denying the researcher's existence and personal investment in the research, the author attempted to implicate "the self in the research by acknowledging her own assumptions, biases and ideologies about autism discourse and practice. Thus, tensions between the self and other, personal and political become woven into the fabric, creating a personal, subjective, and partial account of the phenomenon. This research was intended to explicate and interrogate some of the taken-for-granted Truths which guide our practices with people with autism. This alternative critical framework focused on understanding autism as a discourse and explored the way these dominant autism constructions function in society. Furthermore, positioning "the self in the research was meant to illustrate the fundamental need for self-reflective practice in the social sciences.

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AN EXAMINATION OF NHL FANS' REACTIONS TO THE CANCELLED 2004- 2005 SEASON Chad Asselstine Faculty of Applied Health Sciences, Brock University Gary Bettman, the Commissioner of the National Hockey League (NHL) stepped in front of the worldwide media on February 16, 2005 to announce that there would be no NHL games played during the 2004-2005 season. Two sides were prominent during the labour dispute; the NHL owners and the NHLP A, however a third side that became the forgotten party was the fans (NHLF A, 2005). The fans are the consumers of the NHL and all the brands associated with its franchises, they are the people who provide the revenues that allow owners to pay the players' salaries. The present study is situated within the sport marketing framework, particularly within the fan loyalty literature to provide an understanding of the impact of the 2004- 2005 lockout on the forgotten party, NHL fans. This study examines 16 fans' experiences in four stages: becoming a fan of the NHL, being a fan prior to the lockout, being a fan during the lockout including their anticipated reaction to the return of the NHL, and their actual reaction to the return of the NHL. Data was collected using face-to-face interviews with each ofthe participants, resulting in 16 fans' stories of how the lockout impacted them specifically. Through analysis of the data themes began to emerge including the fans' understanding that there was a need to restructure game play, the business operations of the NHL, a desire for service recovery strategies which would exceed fans' expectations, 4 and the desire for alternative forms of consumption including alternative hockey leagues as well as the growing popularity of poker playing. The study summarizes the effects that the NHL lockout had on the relationship between 16 individual fan~ and their favourite teams, and concludes with Suggestions for Future Research and Implications for Sport Marketers that emerged from this unique case in the history of North American professional sport.

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The purpose of the study was to investigate the effect of a 16 session stickhandling and puck control (SPC) off-ice training intervention on SPC skills and wrist shot performance variables. Eighteen female collegiate ice hockey players participated in a crossover design training intervention, whereby players were randomly assigned to two groups. Each group completed 16 SPC training sessions in two conditions [normal vision (NV) and restricted vision (RV)]. Measures obtained after the training intervention revealed significant improvements in SPC skills and wrist shot accuracy. Order of training condition did not reach significance, meaning that SPC improvement occurred as a result of total training volume as opposed to order of training condition. However, overall changes in the RV-NV condition revealed consistently higher effect sizes, meaning a greater improvement in performance. Therefore, support can be provided for this technical approach to SPC training and an alternative method of challenging SPC skills.

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In this study, I use my own experiences in education as a former elementary student, research assistant, and as a current secondary school teacher, to examine how living in a marginalised rural community challenged by poverty affected my formal education. The purpose of this study was to use stories to: (a) explore my formative elementary education growing up in a community that was experiencing poverty, and; (b) to examine the impact and implications of these experiences for me as a teacher and researcher considering the topic of poverty and education. This study used narrative inquiry to explore stories of education, focusing on experiences living and working in a rural community. My role in the study was both as participant and researcher as I investigate, through story, how I was raised in a marginalised, rural community faced with challenges of poverty and how I relate to my current role as a teacher working in a similar, rural high school. My own experiences and reflections form the basis of the study, but I used the contributions of secondary participants to offer alternative perspective of my interpretation of events. Participants in this study were asked to write about and/or retell their lived stories of working in areas affected by challenging circumstances. From my stories and those of secondary participants, three themes were explored: student authorship, teaching practice, and community involvement. An examination of these themes through commonplaces of place, sociality and time (Connelly and Clandinin, 2006) provide a context for other educators and researchers to consider or reconsider teaching practices in school communities affected by poverty.

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The purpose of this research is to expose and complicate those discourses of childhood imagination as demonstrated in the diagnostic criteria for early onset schizophrenia by using an antipsychiatry perspective. This will be done by evaluating those discourses alongside those found in popular children’s literature, specifically, Harry Potter and The Philosopher’s Stone, Bridge to Terabithia, and A Wrinkle in Time. Once uncovered, the underlying power discourses were then exposed. This research will then employ a minor reading as provided by Deleuze and Guattari’s (1987) approach to minor literature to demonstrate the ways in which the child can subvert those dominant discourses. The potential of literature is evaluated for its ability to provide alternative modes of experience and lines of flight for the child subjected to the diagnostic criteria of schizophrenia.

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Through the reflective lens of an adult educator with invisible and episodic disabilities, this paper has been written as an organizational autoethnography. Through a process of autoethnographical sensemaking, it is intended to illuminate important gaps in organizational theory. Feminist/relational care ethics, critical reflection, and transformative learning serve as the educational theories that comprise its framework. In telling my story, embodied writing and performance narrative are used to convey the felt existence of a body exposed through words—where my “abled” and “disabled” professional teaching and learning identities may be studied against the backdrop of organizational policies and procedures. Words used to describe unfamiliar experiences and situations shape meaning for which new meaning may emerge. At the conclusion of this paper, an alternative frame of reference—a view from the margins—may be offered to articulate authenticity in the expectancy of workplace equity for adult educators with disabilities. Taken collectively on a larger level, it is hoped that this research may provide a source of inspiration for systemic organizational change in adult learning environments.

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Presented at the Annual Conference of the Canadian Political Science Association, Brock University, St. Catharines, Ontario, May 27, 2014