γ-aminobutyric acid is the major inhibitory neurotransmitter in the adult mammalian central nervous system (CNS) and may also play a neurotrophic role during CNS development. Diversification of GABA_A receptor mediated responses are in part a result ofvariation in subunit composition in the receptor complex. This variation arises both from the number of different subtypes of GABA_A receptor subunits (α1-6, β1-4, γ1-3, δ1, ρ1-3, ε, ρ), as well as from post-transcriptional processes such as RNA splicing. In this thesis, I have investigated the developmental onset of GABA_A receptor gene expression and the distribution and temporal expression of GABA_A receptor subunit mRNAs and 12 splice variants within the developing and adult murine CNS. Preliminary studies using S 1 nuclease protection analysis demonstrated that α1, β3 and γ2 were the predominant subtypes of GABA_A receptor subunits expressed at embryonic day 14 and in the adult murine CNS. In situ hybridisation analysis demonstrated overlapping but distinct spatial and temporal patterns of GABA_A subunit mRNA expression during postnatal development and in the adult murine CNS. Analysis of γ2 mRNA splice variants demonstrated that the γ2S transcript is the predominant γ2 mRNA expressed during latter stages of embryo genesis, while the γ2L transcript is the predominant γ2 isoform present inthe adult CNS. Since there is a 29 to 47 percent amino acid identity among the various GABA_A receptor subunits, I have also demonstrated through site-directed mutagenesis studies, that changes in a conserved amino acid in the cysteine loop of the bovine a 1 GABA_A receptor subunit resulted in a loss of agonist and antagonist binding (DI49N), while a change in a conserved amino acid in the M1 transmembrane domain of the bovine α1 GABA_A receptor subunit resulted in loss of agonist binding and reduction in the B_max and K_d for antagonist binding (P243A). 'These results are in contrast to the effect of identical mutations in the bovine β1 subunit and suggest that if the pentameric GABA_A receptor assembly is composed of (α1)2(β1)1(γ2)2, then changes in highly conserved amino acids in the α1 receptor subunit would have a greater distortion on the structure of the receptor complex.

abstract: A tiling is a collection of vertex disjoint subgraphs called tiles. If the tiles are all isomorphic to a graph $H$ then the tiling is an $H$-tiling. If a graph $G$ has an $H$-tiling which covers all of the vertices of $G$ then the $H$-tiling is a perfect $H$-tiling or an $H$-factor. A goal of this study is to extend theorems on sufficient minimum degree conditions for perfect tilings in graphs to directed graphs. Corrádi and Hajnal proved that every graph $G$ on $3k$ vertices with minimum degree $delta(G)ge2k$ has a $K_3$-factor, where $K_s$ is the complete graph on $s$ vertices. The following theorem extends this result to directed graphs: If $D$ is a directed graph on $3k$ vertices with minimum total degree $delta(D)ge4k-1$ then $D$ can be partitioned into $k$ parts each of size $3$ so that all of parts contain a transitive triangle and $k-1$ of the parts also contain a cyclic triangle. The total degree of a vertex $v$ is the sum of $d^-(v)$ the in-degree and $d^+(v)$ the out-degree of $v$. Note that both orientations of $C_3$ are considered: the transitive triangle and the cyclic triangle. The theorem is best possible in that there are digraphs that meet the minimum degree requirement but have no cyclic triangle factor. The possibility of added a connectivity requirement to ensure a cycle triangle factor is also explored. Hajnal and Szemerédi proved that if $G$ is a graph on $sk$ vertices and $delta(G)ge(s-1)k$ then $G$ contains a $K_s$-factor. As a possible extension of this celebrated theorem to directed graphs it is proved that if $D$ is a directed graph on $sk$ vertices with $delta(D)ge2(s-1)k-1$ then $D$ contains $k$ disjoint transitive tournaments on $s$ vertices. We also discuss tiling directed graph with other tournaments. This study also explores minimum total degree conditions for perfect directed cycle tilings and sufficient semi-degree conditions for a directed graph to contain an anti-directed Hamilton cycle. The semi-degree of a vertex $v$ is $min{d^+(v), d^-(v)}$ and an anti-directed Hamilton cycle is a spanning cycle in which no pair of consecutive edges form a directed path. / Dissertation/Thesis / Ph.D. Mathematics 2013

Organisations worldwide are attempting to increase individual job satisfaction, productivity and efficiency by implementing work teams. This research study evaluates the interventions considered necessary to optimally implement and maintain self-directed work teams (SDWTs). In order to complete this study it was necessary to address the characteristics associated with SDWTs, problems commonly experienced during implementation and functioning of SDWTs and the identification of the interventions used to promote the successful implementation and maintenance of SDWTs. These objectives were achieved by means of a comprehensive literature study. Subsequent to the literature study, a process model for the successful implementation and maintenance of a SDWT within a South African organization was developed. Thereafter, a questionnaire was developed based on the findings of the literature study and distributed to a randomly selected population. The objective of the questionnaire was to evaluate the interventions utilized during the implementation and maintenance of SDWTs. The results of the empirical study were statistically analysed and interpreted. Finally, conclusions and recommendations were made. The most important recommendations are as follows: Firstly, the trade union must be consulted and involved in the decision to implement SDWTs. Members of the team must be exposed to training interventions prior to the implementation of the SDWT. Thereafter, team members must undergo advanced training in interpersonal and problemsolving skills. Salary and reward structures within the organisation must be adapted to suit a teambased environment. Finally, the success of the SDWT will depend on the support provided by management. Management needs to exhibit total commitment to the change on a continuous basis.

Background: Heart failure is a clinical syndrome occurring from the heart’s inability to effectively fill and or pump blood, it is the most common reason for admission in elderly patients. Guideline directed medical therapy refers to implementation of all class I agents to reduce patient morbidity and mortality, unless there is an appropriate contraindication. Appropriate beta blocker (BB), angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB), and aldosterone antagonist (AA) are recommended to be prescribed together prior to discharge for a hospital admission for decompensated heart failure with reduced ejection fraction (HFrEF). Get With The Guidelines – Heart Failure (GWTG- HF) is an online quality improvement project that assists hospitals in providing guideline directed care. Objective: The purpose of this study was to determine if implementation of the GWTG-HF program, increases provider adherence to guideline directed medical therapy (GDMT) for patients admitted with a primary diagnosis of decompensated HFrEF at Banner University Medical Center Tucson (BUMCT). Design: This is a quality improvement project with a pre and post test descriptive design. Setting: BUMCT from 10/04/17 – 11/08/17 Participants: Fifty-five patients discharged with the primary diagnosis of decompensated HFrEF Measurements: Baseline guideline adherence for a 30-day period was compared to guideline adherence after the initiation of the GWTG-HF program. Results: The 24 patients pre intervention were compared to 31 patients post intervention. The following results were found when comparing pre and post adherence rates: BB adherence 92% versus 100%, ACEI/ARB adherence 100% versus 94%, AA adherence 67% versus 84%, and guideline directed medical therapy 58% versus 81%. There were no statistically significant differences for the pre and post adherence rates. Conclusion: Although, there were no statistically significant differences found to support that implementation of the GWTG-HF program, increases providers adherence to GDMT for patients admitted with a primary diagnosis of decompensated HFrEF, the trends were clear. In three out of four class I agents, there was an increase in appropriate provider prescribing per the guidelines.

No description available.

Mechanistically and structurally chloroperoxidase (CPO) occupies a unique niche among heme containing enzymes. Chloroperoxidase catalyzes a broad range of reactions, such as oxidation of organic substrates, dismutation of hydrogen peroxide, and mono-oxygenation of organic molecules. To expand the synthetic utility of CPO and to appreciate the important interactions that lead to CPO’s exceptional properties, a site-directed mutagenesis study was undertaken. Recombinant CPO and CPO mutants were heterologously expressed in Aspergillus niger. The overall protein structure was almost the same as that of wild type CPO, as determined by UV-vis, NMR and CD spectroscopies. Phenylalanine103, which was proposed to regulate substrate access to the active site by restricting the size of substrates and to control CPO’s enantioselectivity, was mutated to Ala. The ligand binding affinity and most importantly the catalytic activity of F103A was dramatically different from wild type CPO. The mutation essentially eliminated the chlorination and dismutation activities but enhanced, 4-10 fold, the epoxidation, peroxidation, and N-demethylation activities. As expected, the F103A mutant displayed dramatically improved epoxidation activity for larger, more branched styrene derivatives. Furthermore, F103A showed a distinctive enantioselectivity profile: losing enantioselectivity to styrene and cis-β-methylstyrene; having a different configuration preference on α-methylstyrene; showing higher enatioselectivites and conversion rates on larger, more branched substrates. Our results show that F103 acts as a switch box that controls the catalytic activity, substrate specificity, and product enantioselectivity of CPO. Given that no other mutant of CPO has displayed distinct properties, the results with F103A are dramatic. The diverse catalytic activity of CPO has long been attributed to the presence of the proximal thiolate ligand. Surprisingly, a recent report on a C29H mutant suggested otherwise. A new CPO triple mutant C29H/C79H/C87H was prepared, in which all the cysteines were replaced by histidine to eliminate the possibility of cysteine coordinating to the heme. No active form protein was isolated, although, successful transformation and transcription was confirmed. The result suggests that Cys79 and Cys87 are critical to maintaining the structural scaffold of CPO. In vitro biodegradation of nanotubes by CPO were examined by scanning electron microscope method, but little oxidation was observed.

The distance d(u,v) from vertex u to vertex v in a digraph G is the length of the shortest directed path from u to v. The eccentricity e(v) of vertex v is the maximum distance of v to any other vertex of G. A vertex u is an eccentric vertex of vertex v if the distance from v to u is equal to the eccentricity of v. The eccentric digraph ED(G) of a digraph G is the digraph that has the same vertex set as G and the arc set defined by: there is an arc from u to v iff v is an eccentric vertex of u. The idea of the eccentric digraph of a graph was introduced by Buckley (Congr. Numer. 149 (2001) 65) and the idea of the eccentric digraph of a digraph by Boland and Miller (Proceedings of AWOCA'01, July 2001, p. 66). In this paper, we examine eccentric digraphs of digraphs for various families of digraphs and we consider the behaviour of an iterated sequence of eccentric digraphs of a digraph. The paper concludes with several open problems.

Experimental studies suggest alcohol facilitates deliberate self-harm (DSH). One explanation might be that alcohol increases pain tolerance (PT), which may then lead to DSH. This study aimed to examine whether PT mediated the relationship between alcohol and DSH. Further, alcohol is neither necessary nor sufficient to self-harm. Given past non-suicidal self-injury (NSSI) is a good predictor of future DSH, NSSI may moderate these relationships. This study also aimed to examine if mediation was conditional upon past NSSI. Participants (106 men and 104 women) reported on past NSSI and received a drink sufficient to produce target blood-alcohol content (BAC = .000%, .050%, .075%, or .100%). Participants completed a behavioral measure of DSH. Results revealed that the association between BAC and DSH was mediated through PT. Additionally, past NSSI moderated the path between PT and DSH but did not affect the path between BAC and PT. Clinical implications and limitations are discussed.

Indiana University-Purdue University Indianapolis (IUPUI) / Subnetwork or path mining is an emerging data mining problem in many areas including scientific and commercial applications. Graph modeling is one of the effective ways in representing real world networks. Many natural and man-made systems are structured in the form of networks. Traditional machine learning and data mining approaches assume data as a collection of homogenous objects that are independent of each other whereas network data are potentially heterogeneous and interlinked. In this paper we propose a novel algorithm to find subnetworks and Maximal paths from a weighted, directed network represented as a graph. The main objective of this study is to find meaningful Maximal paths from a given network based on three key parameters: node weight, edge weight, and direction. This algorithm is an effective way to extract Maximal paths from a network modeled based on a user’s interest. Also, the proposed algorithm allows the user to incorporate weights to the nodes and edges of a biological network. The performance of the proposed technique was tested using a Colorectal Cancer biological network. The subnetworks and paths obtained through our network mining algorithm from the biological network were scored based on their biological significance. The subnetworks and Maximal paths derived were verified using MetacoreTM as well as literature. The algorithm is developed into a tool where the user can input the node list and the edge list. The tool can also find out the upstream and downstream of a given entity (genes/proteins etc.) from the derived Maximal paths. The complexity of finding the algorithm is found to be O(nlogn) in the best case and O(n^2 logn) in the worst case.

Thesis advisor: Abhishek Chatterjee / Thesis advisor: Eranthie Weerapana / In nature, just twenty canonical amino acids are responsible for the creation of nearly all proteins. Genetic code expansion (GCE), or the incorporation of noncanonical amino acids (ncAAs) into living cells, is a powerful tool that expands the studies we are capable of performing using proteins. This technology relies on engineered aminoacyl-tRNA synthetase (aaRS)/tRNA pairs that are orthogonal to the host cells’ endogenous aaRS/tRNA pairs, and one of the main limitations of GCE arises from the inefficiency of these suppressor tRNAs when expressed in a foreign host cell. To address this limitation, we have previously reported a strategy for the virus-assisted directed evolution of tRNAs (VADER) which is uniquely capable of addressing the specific needs of tRNA evolution. In order to advance the capabilities of VADER, we made a number of modifications to the VADER selection scheme. First, we designed and executed a modified VADER selection that enabled the evolution of a new class of tRNAs, and with this VADER selection, we were able to generate a first-generation E. coli tyrosyl tRNA (tRNATyr) variant that was three times as active as its wild-type equivalent. Next, we introduced a number of refinements to the VADER strategy to generate VADER 2.0, an improved workflow capable of screening larger libraries and libraries encoding more active variants. Using VADER 2.0, we created second-generation tRNAPyl and tRNATyr mutants that achieved incorporation efficiencies that were greater than five-fold higher than their wild-type equivalents across a wide variety of substrates, enabling exciting GCE experiments that would not be possible otherwise. / Thesis (PhD) — Boston College, 2023. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.