1,754 research outputs found
Consumer use and response to online third-party raw DNA interpretation services
This study was funded in part by a pilot grant from the Boston University School of Public Health. (Boston University School of Public Health)Published versio
Epitope mapping using mRNA display and a unidirectional nested deletion library
In vitro selection targeting an anti-polyhistidine monoclonal antibody was performed using mRNA display with a random, unconstrained 27-mer peptide library. After six rounds of selection, epitope-like peptides were identified that contain two to five consecutive, internal histidines and are biased for arginine residues, without any other identifiable consensus. The epitope was further refined by constructing a high-complexity, unidirectional fragment library from the final selection pool. Selection by mRNA display minimized the dominant peptide from the original selection to a 15-residue functional sequence (peptide Cmin: RHDAGDHHHHHGVRQ; K-D = 38 nM). Other peptides recovered from the fragment library selection revealed a separate consensus motif (ARRXA) C-terminal to the histidine track. Kinetics measurements made by surface plasmon resonance, using purified Fab (antigen-binding fragment) to prevent avidity effects, demonstrate that the selected peptides bind with 10- to 75-fold higher affinities than a hexahistidine peptide. The highest affinity peptides (K-D approximate to 10 nM) encode both a short histidine track and the ARRXA motif, suggesting that the motif and other flanking residues make important contacts adjacent to the core polyhistidine-binding site and can contribute > 2.5 kcal/mol of binding free energy. The fragment library construction methodology described here is applicable to the development of high-complexity protein or cDNA expression libraries for the identification of protein-protein interaction domains
Small Business Crews As High Performance Work Teams: The Role Of Vertical And Horizontal Familiarity
This research focused on the influence of vertical team familiarity (past work experience between leader and members) and horizontal team familiarity (past work experience between members) on fluid team financial job performance. Utilizing role theory (Foa & Foa, 1974), leader-member exchange (Graen & Scandura, 1984) and team-member exchange (Seers, 1989) theories, within Grant\u27s (2007) relational job design model, a conceptual model is developed and then empirically tested. It is proposed that through vertical team familiarity and horizontal team familiarity resource exchange relationships develop which influence team financial job performance. The effect of vertical team familiarity on team financial job performance is hypothesized to operate through the intervening variables, horizontal team familiarity, team operational job performance, and diverse team competence. The findings from this study indicate that vertical team familiarity positively influences financial job performance through horizontal team familiarity. This suggest that when fluid team leaders\u27 compose a team bases on members past shared teamwork experiences the leader positively influences financial job performance through horizontal familiarity. Furthermore, team competence was found to be negatively related to team financial job performance indicating that when selecting team members, leaders will better serve the organization by focusing on relationships formed between members
Maxillary expansion in an animal model with light, continuous force
Objectives: Maxillary constriction is routinely addressed with rapid maxillary expansion (RME). However, the heavy forces delivered by most RME appliances to expand the palate may lead to deleterious effects on the teeth and supporting tissues. The objective of this study was to explore a more physiologic maxillary expansion with light continuous force.
Materials and Methods: Twenty 6-week-old Sprague-Dawley rats were equally divided into experimental (EXPT) and control (CTRL) groups. A custom-fabricated archwire expansion appliance made from 0.014-inch copper-nickel-titanium wire was activated 5 mm and bonded to the maxillary molar segments of animals in the EXPT group for 21 days. The force applied to each maxillary segment was 5 cN. Microfocus x-ray computed tomography and histological analyses were used to compare the tooth movement and bone morphology in the midpalatal suture and buccal aspect of the alveolar process between the EXPT and CTRL groups. Descriptive statistics (mean ± standard error of the mean) and nonparametric statistical tests were used to compare the outcomes across groups.
Results: Compared to the CTRL group, there was a statistically significant increase in buccal tooth movement and expansion of the midpalatal suture in the EXPT group. There was no difference in the bone morphologic parameters between groups. The mineral apposition rate was increased on the buccal surface of the alveolar process in the EXPT group.
Conclusions: Application of light, continuous force resulted in maxillary osseous expansion due to bilateral sutural apposition and buccal drift of the alveolar processes. This animal experiment provides a more physiologic basis for maxillary expansion
Exploring the cellular effects of small molecule inhibitors of Oxysterol-binding Protein
Oxysterol-binding protein (OSBP) is the founding member of a conserved protein family found among eukaryotes that functions as a lipid transporter between the ER and Golgi. OSBP is ubiquitously expressed in all tissues and is an essential host protein in the viral replication of many public health menaces, especially the Enteroviruses. Over the past decade, many broad-spectrum anti-viral small molecules have been identified as OSBP inhibitors. The anti-cancer and anti-viral natural product, OSW-1, is of interest due to its high affinity for OSBP and its ability to cause proteasomal degradation of OSBP. The work outlined in this dissertation details the unique ability of the OSW-1 compound to induce persistent OSBP repression in cells through multiple days without affecting cell viability. Even in the absence of the OSW-1 compound, the reduced OSBP levels confers a prophylactic anti-viral activity against clinical isolates of Enterovirus viruses. This long-term reduction is specific for OSBP in the proteasome, and reduction occurs through an unknown mechanism that does not involve OSBP proteolysis or transcriptional repression. Of the known OSBP small molecule inhibitors with anti-viral activity, only OSW-1 triggered the long-term repression of OSBP. The OSBP inhibitor compound T-00127-HEV2 was the only compound tested able to protect OSBP levels from the OSW-1-induced repression of the protein. Of the OSBP inhibitor compounds, only the OSW-1 compound was able to induce the prophylactic anti-viral response against two clinical isolates of Enterovirus viruses. The results produced will be beneficial in future research that seeks to define OSBP cellular regulation, especially upon OSW-1 treatment, and to potentially develop prophylactic anti-viral therapeutics through targeting OSBP
The Role of Surface Drag in Supercell Tornadogenesis and Mesocyclogenesis: Studies Based on Idealized Numerical Simulations
Idealized numerical simulations of supercell thunderstorms have been employed for several decades to study tornadogenesis, providing valuable insights that have helped shape our current understanding of the process. Until the past several years, however, most of these simulations used a free-slip lower boundary condition, effectively disregarding the effects of surface drag. In this study, 50-m (tornado-resolving) idealized simulations of a supercell thunderstorm are performed using the Advanced Regional Prediction System (ARPS) with parameterized surface drag. Analyses of the dynamics of low-level mesocyclogenesis and tornadogenesis are conducted.
Two sets of experiments are performed and analyzed in this study. First, a pair of experiments is performed to identify mechanisms by which drag affects storm behavior. In the first experiment (full-wind drag), surface drag is applied to the full wind components; in the second experiment (environmental drag), drag is applied only to the background environmental wind, with storm-induced perturbations unaffected. In the full-wind drag experiment, a tornado develops around 25 min into the simulation and persists for more than 10 min; in the environmental drag experiment, no tornado occurs. An important mechanism leading to tornadogenesis in the full-wind drag experiment is the generation of near-ground crosswise horizontal vorticity by drag on the storm scale as inflow air accelerates into the low-level mesocyclone; this vorticity is subsequently exchanged into the streamwise direction and eventually tilted into the vertical. Preceding tornadogenesis, the low-level mesocyclone in the full-wind drag experiment also intensifies and lowers rapidly toward the ground, which does not occur in the environmental drag experiment. Circulation budgets for material circuits enclosing the low-level mesocyclone reveal substantial generation of new circulation by surface drag in the full-wind drag experiment, while the mesocyclone circulation in the environmental-drag experiment is primarily barotropic in origin.
A second set of experiments is performed in which the drag coefficient (Cd) is varied over a range of values appropriate for water and land. The initial low-level mesocyclone lowers toward the ground, intensifies, and produces a tornado in all experiments with Cd > 0, with the intensification occurring earlier for larger Cd; in the no-drag experiment, the low-level mesocyclone remains comparatively weak during this period. Circulation budgets for material circuits initialized around the mesocyclone again implicate surface drag acting in the inflow region as having generated important new circulation. Although a greater relative contribution from drag is seen as Cd increases, the difference between the last two experiments (Cd = 0.02, Cd = 0.05) is minimal and the tornado in the latter experiment is weaker, suggesting an upper limit on the drag coefficient for the favorability of this circulation-generating mechanism. Later in the simulations, after precipitation-driven outflow encloses much of the near-ground mesocyclone, tornadoes in experiments with large Cd tend to be weaker and shorter-lived than those in experiments with small Cd. Circulation analysis of a tornado in one strong-drag experiment suggests that the previously described mechanism may still be important even for tornadoes in this context, where baroclinic vorticity is readily available near the vortex. Implications of the proposed roles of surface drag in supercell tornadogenesis dynamics are discussed, and suggestions for future work are offered
An investigation of theory-practice gap in undergraduate paramedic education
<p>Abstract</p> <p>Background</p> <p>Bachelor of Emergency Health (Paramedic) (BEH) students at Monash University undertake clinical placements to assist with the transition from student to novice paramedic. Anecdotally, students report a lack of opportunity to practise their clinical skills whilst on placements. The barriers to participation and the theory-practice gap have not been previously documented in Australian paramedic literature. The purpose of this study was to investigate the theory-practice gap for paramedic students by linking education and skill level to case exposure and skills praxis during clinical placements.</p> <p>Methods</p> <p>A cross-sectional retrospective study using a convenience sample of second and third year BEH undergraduate students. Ethics approval was granted.</p> <p>Results</p> <p>Eighty four second and third year BEH students participated. 59.5% were female (n = 50), 40.5% were male (n = 34). Overall, students most commonly reported exposure to cardiac and respiratory cases and were satisfied with the number of cases encountered during placement. However, over half (n = 46) reported being exposed to < 50% of cases that allowed skills praxis. The most common barrier to participation (34.5%) was the opportunity to participate in patient care and 68% of student's were unsure if paramedics understood their role during clinical placements.</p> <p>Conclusion</p> <p>This study demonstrates that the majority of students were satisfied with their clinical placement experience; even though they were exposed to < 50% of cases that allowed skills practice. Identifying these educational barriers will assist in improving the quality and theory-practice gap of paramedic clinical education.</p
Upper Atmospheric Monitoring for Ares I-X Ascent Loads and Trajectory Evaluation on the Day-of-Launch
During the launch countdown of the Ares I-X test vehicle, engineers from Langley Research Center will use profiles of atmospheric density and winds in evaluating vehicle ascent loads and controllability. A schedule for the release of balloons to measure atmospheric density and winds has been developed by the Natural Environments Branch at Marshall Space Flight Center to help ensure timely evaluation of the vehicle ascent loads and controllability parameters and support a successful launch of the Ares I-X vehicle
The GABAA Receptor delta Subunit Gene Promoter: Characterisation and Use
Viral vectors represent powerful tools in the rapidly developing field of gene therapy of the mammalian central nervous system. Interest in HSV-1 in particular as a vector relates primarily to its ability to establish long-term latent infections in neuronal cells. A goal of this research was the development of a safe HSV-1 vector that would deliver a reporter gene to target cells in the CNS and restrict its expression to a specific cell-type by the use of a neuronal promoter. A second goal was to add to the present limited understanding of neuron-specific promoter structure. The murine GABAA receptor delta subunit gene promoter was selected for use as a prototype neuronal promoter as it is moderately expressed and has a well characterised restricted expression pattern in the CNS. Characterisation of the 5'- romoter region of the GABAA receptor 6 subunit gene was achieved by sequencing 10.5 kb of DNA from the 5'-upstream region. Analysis of this sequence revealed the presence of several putative recognition sites for transcription factors. Identification of the transcription start points showed two main clusters of start sites located 58 and 108 bases upstream from the translational start point. Comparison of about 3.5 kb of DNA sequence of the promoters of the rat and mouse genes showed a high degree of conservation of noncoding sequence between the species. The recognition site for a putative regulatory factor BSF 1 identified in the 5'-upstream sequence of the rat delta gene was demonstrated to be absent in the mouse 5'-flanking sequence. Analysis of a range of promoter - reporter constructs in the NB4 1A3 cell line suggested the presence of a silencing element located between 4.5 kb and 6.3 kb upstream of the translational start point. As a preliminary step to evaluating in vivo mutagenesis investigations of GABAA receptor 5 subunit gene promoter function, targeted disruption of the GABAA receptor 6 subunit gene in embryonic stem cells was achieved. Two genomic DNA fragments from the GABAA receptor 5 subunit gene were selected and inserted into a simple replacement vector (pNT) containing the neomycin gene and the HSV thymidine kinase gene. A successful targeting event would result in the removal of the first exon, 4.5 kb of promoter sequence and 2 kb of DNA from the first intron. Two targeted embryonic stem cell lines were isolated and can be used to make mice homozygous for the mutated gene. The GABAA receptor delta subunit gene had previously been assigned to human Chromosome Ip. Genetic mapping of the gene to rat chromosome 5 and mouse chromosome 4 was performed. These results agree with expected regions of synteny between human, mouse and rat. A range of recombinant HSV-1 viruses were produced which contained the E coli lacZ gene driven by different promoters. Two loci within the HSV-1 genome were chosen as sites of insertion, LAT and UL43 in two HSV-1 viral variants, 1716 and 1764. Infection of primary cerebellar granule cell cultures with a range of these recombinant viruses revealed that the cerebellar granule cells were not readily infected by this viral variant. Stereotactic injection of the viruses into the cerebellum of adult rats failed to show specific P-galactosidase expression. Nevertheless, the GABAA receptor delta subunit gene promoter-lacZ fusion constructs can now be transferred to new HSV-1 vectors with better growth characteristics thus furthering the original goal of this work
A standardised nutritional drink as a test meal for the 13 C mixed triglyceride breath test for pancreatic exocrine insufficiency:A randomised, two-arm crossover comparative study
BACKGROUND: The 13 C mixed triglyceride breath test (13 C MTGT) is a diagnostic test for pancreatic exocrine insufficiency (PEI). It is poorly standardised with much heterogeneity of the test meal, the commonest being toast and butter. A standardised oral nutritional supplement that could be easily transported, stored and made up would be valuable for making this test accessible outside of specialist centres.METHODS: A prospective, randomised, two-arm crossover study of different test meals was carried out in 14 healthy controls. The 13 C MTGT was performed in identical conditions on two separate days. Two test meals were given in random order, either standard (toast and butter) or novel (oral nutritional supplement), with 250 mg of 13 C-labelled mixed triglyceride incorporated. Breath samples were taken postprandially to calculate cumulative percentage dose recovery (cPDR) of 13 C at 6 h.RESULTS: All 14 participants completed both arms of the study with no protocol deviations. The mean cPDR was 39.39% (standard deviation [SD] 5.19) for the standard test meal and 39.93% (SD 5.20) for the novel test meal. A one-way repeated measures analysis of variance (ANOVA) found no significant difference in cPDR between the two meals, F(1, 13) = 0.18, p = 0.68 (minimum detectable difference of 0.81 at 80% power).CONCLUSION: This study demonstrates that a standardised oral nutritional supplement can be used without compromising 13 C recovery. Using this test meal provides a standardised dietary stimulus to the pancreas, avoiding possible variation in quantity of dietary components with other test meals. Further, the ease of use of this method would help establish the 13 C MTGT test more widely.</p
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