381 research outputs found

    Testing the Association between Negative Appraisal and Traumatic Stress Symptoms among Community Clients with Serious Mental Illness

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    Thesis advisor: Ce ShenA compelling body of literature suggests that negative appraisal may be associated with adverse reactions to traumatic stress (Ehlers & Clark, 2000). However, very few studies have examined how cognitive appraisal influences posttraumatic adaptation in people with serious mental illness (SMI) despite evidence of disproportionately high prevalence rates of trauma exposure and Posttraumatic Stress Disorder (PTSD) in this population. The major purpose of this study was to examine the relationship between negative appraisal and PTSD symptoms among adults diagnosed with SMI. It was hypothesized that negative appraisal would have a positive and significant association with traumatic stress symptoms in a clinical sample of community clients diagnosed with major mood and schizophrenia-spectrum disorders when controlling for gender, total lifetime trauma, substance use, and severity of symptoms associated with SMI. Multiple regression was employed to conduct a secondary analysis of clinical data from 291 community support clients who were receiving services from three community mental health centers in the state of Rhode Island during March to September 2009. Results supported the main hypotheses that all three types of negative appraisal with respect to self, world /others, and self blame as well as overall appraisal were positively and significantly associated with PTSD symptoms.Thesis (PhD) — Boston College, 2011.Submitted to: Boston College. Graduate School of Social Work.Discipline: Social Work

    C-terminal domain of archaeal O-phosphoseryl-tRNA kinase displays large-scale motion to bind the 7-bp D-stem of archaeal tRNASec

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    O-Phosphoseryl-tRNA kinase (PSTK) is the key enzyme in recruiting selenocysteine (Sec) to the genetic code of archaea and eukaryotes. The enzyme phosphorylates Ser-tRNASec to produce O-phosphoseryl-tRNASec (Sep-tRNASec) that is then converted to Sec-tRNASec by Sep-tRNA:Sec-tRNA synthase. Earlier we reported the structure of the Methanocaldococcus jannaschii PSTK (MjPSTK) complexed with AMPPNP. This study presents the crystal structure (at 2.4-Å resolution) of MjPSTK complexed with an anticodon-stem/loop truncated tRNASec (Mj*tRNASec), a good enzyme substrate. Mj*tRNASec is bound between the enzyme’s C-terminal domain (CTD) and N-terminal kinase domain (NTD) that are connected by a flexible 11 amino acid linker. Upon Mj*tRNASec recognition the CTD undergoes a 62-Å movement to allow proper binding of the 7-bp D-stem. This large reorganization of the PSTK quaternary structure likely provides a means by which the unique tRNASec species can be accurately recognized with high affinity by the translation machinery. However, while the NTD recognizes the tRNA acceptor helix, shortened versions of MjPSTK (representing only 60% of the original size, in which the entire CTD, linker loop and an adjacent NTD helix are missing) are still active in vivo and in vitro, albeit with reduced activity compared to the full-length enzyme

    Pre-Steady-State Kinetic Analysis of Truncated and Full-Length Saccharomyces cerevisiae DNA Polymerase Eta

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    Understanding polymerase fidelity is an important objective towards ascertaining the overall stability of an organism's genome. Saccharomyces cerevisiae DNA polymerase η (yPolη), a Y-family DNA polymerase, is known to efficiently bypass DNA lesions (e.g., pyrimidine dimers) in vivo. Using pre-steady-state kinetic methods, we examined both full-length and a truncated version of yPolη which contains only the polymerase domain. In the absence of yPolη's C-terminal residues 514–632, the DNA binding affinity was weakened by 2-fold and the base substitution fidelity dropped by 3-fold. Thus, the C-terminus of yPolη may interact with DNA and slightly alter the conformation of the polymerase domain during catalysis. In general, yPolη discriminated between a correct and incorrect nucleotide more during the incorporation step (50-fold on average) than the ground-state binding step (18-fold on average). Blunt-end additions of dATP or pyrene nucleotide 5′-triphosphate revealed the importance of base stacking during the binding of incorrect incoming nucleotides

    Historical and architectural survey of Anderson County, South Carolina : final report

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    The historic resource survey of Anderson County was undertaken to compile an up-to-date, accurate inventory of historic properties located within the boundaries of the county. The information was compiled in order to identify properties and districts that should be considered for possible local designation and National Register designation, as well as to aid the local governments in preservation planning and cultural tourism development

    Structural insights into RNA-dependent eukaryal and archaeal selenocysteine formation

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    The micronutrient selenium is present in proteins as selenocysteine (Sec). In eukaryotes and archaea, Sec is formed in a tRNA-dependent conversion of O-phosphoserine (Sep) by O-phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS). Here, we present the crystal structure of Methanococcus maripaludis SepSecS complexed with PLP at 2.5 Å resolution. SepSecS, a member of the Fold Type I PLP enzyme family, forms an (α2)2 homotetramer through its N-terminal extension. The active site lies on the dimer interface with each monomer contributing essential residues. In contrast to other Fold Type I PLP enzymes, Asn247 in SepSecS replaces the conserved Asp in binding the pyridinium nitrogen of PLP. A structural comparison with Escherichia coli selenocysteine lyase allowed construction of a model of Sep binding to the SepSecS catalytic site. Mutations of three conserved active site arginines (Arg72, Arg94, Arg307), protruding from the neighboring subunit, led to loss of in vivo and in vitro activity. The lack of active site cysteines demonstrates that a perselenide is not involved in SepSecS-catalyzed Sec formation; instead, the conserved arginines may facilitate the selenation reaction. Structural phylogeny shows that SepSecS evolved early in the history of PLP enzymes, and indicates that tRNA-dependent Sec formation is a primordial process

    Divergence of selenocysteine tRNA recognition by archaeal and eukaryotic O-phosphoseryl-tRNASec kinase

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    Selenocysteine (Sec) biosynthesis in archaea and eukaryotes requires three steps: serylation of tRNASec by seryl-tRNA synthetase (SerRS), phosphorylation of Ser-tRNASec by O-phosphoseryl-tRNASec kinase (PSTK), and conversion of O-phosphoseryl-tRNASec (Sep-tRNASec) by Sep-tRNA:Sec-tRNA synthase (SepSecS) to Sec-tRNASec. Although SerRS recognizes both tRNASec and tRNASer species, PSTK must discriminate Ser-tRNASec from Ser-tRNASer. Based on a comparison of the sequences and secondary structures of archaeal tRNASec and tRNASer, we introduced mutations into Methanococcus maripaludis tRNASec to investigate how Methanocaldococcus jannaschii PSTK distinguishes tRNASec from tRNASer. Unlike eukaryotic PSTK, the archaeal enzyme was found to recognize the acceptor stem rather than the length and secondary structure of the D-stem. While the D-arm and T-loop provide minor identity elements, the acceptor stem base pairs G2-C71 and C3-G70 in tRNASec were crucial for discrimination from tRNASer. Furthermore, the A5-U68 base pair in tRNASer has some antideterminant properties for PSTK. Transplantation of these identity elements into the tRNASerUGA scaffold resulted in phosphorylation of the chimeric Ser-tRNA. The chimera was able to stimulate the ATPase activity of PSTK albeit at a lower level than tRNASec, whereas tRNASer did not. Additionally, the seryl moiety of Ser-tRNASec is not required for enzyme recognition, as PSTK efficiently phosphorylated Thr-tRNASec
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