Purdue University

About: Purdue University is a education organization based out in West Lafayette, Indiana, United States. It is known for research contribution in the topics: Population & Heat transfer. The organization has 73219 authors who have published 163563 publications receiving 5775236 citations. The organization is also known as: Purdue & Purdue-West Lafayette.

Relative performance of Bayesian clustering software for inferring population substructure and individual assignment at low levels of population differentiation

Abstract: Traditional methods for characterizing genetic differentiation among populations rely on a priori grouping of individuals. Bayesian clustering methods avoid this limitation by using linkage and Hardy–Weinberg disequilibrium to decompose a sample of individuals into genetically distinct groups. There are several software programs available for Bayesian clustering analyses, all of which describe a decrease in the ability to detect distinct clusters as levels of genetic differentiation among populations decrease. However, no study has yet compared the performance of such methods at low levels of population differentiation, which may be common in species where populations have experienced recent separation or high levels of gene flow. We used simulated data to evaluate the performance of three Bayesian clustering software programs, PARTITION, STRUCTURE, and BAPS, at levels of population differentiation below FST=0.1. PARTITION was unable to correctly identify the number of subpopulations until levels of FST reached around 0.09. Both STRUCTURE and BAPS performed very well at low levels of population differentiation, and were able to correctly identify the number of subpopulations at FST around 0.03. The average proportion of an individual’s genome assigned to its true population of origin increased with increasing FST for both programs, reaching over 92% at an FST of 0.05. The average number of misassignments (assignments to the incorrect subpopulation) continued to decrease as FST increased, and when FST was 0.05, fewer than 3% of individuals were misassigned using either program. Both STRUCTURE and BAPS worked extremely well for inferring the number of clusters when clusters were not well-differentiated (FST=0.02–0.03), but our results suggest that FST must be at least 0.05 to reach an assignment accuracy of greater than 97%.

Prevalence of traumatic events and post‐traumatic psychological symptoms in a nonclinical sample of college students

Abstract: The lifetime prevalence of traumatic events and their psychological impact were assessed in 440 undergraduate students. Eighty-four percent of the subjects reported experiencing at least one event of sufficient intensity potentially to elicit Post-Traumatic Stress Disorder (PTSD). One-third of the sample had experienced four or more traumatic events. Subjects who had experienced trauma reported higher levels of depression, anxiety, and PTSD symptomatology than nontraumatized subjects, and these symptoms were more intense in subjects who experienced multiple traumas. Events that were particularly negative in their impact included unwanted sexual experiences and events that subjects reported were too traumatic to discuss openly. Males and females differed in their probability of experiencing some types of events and in the psychological response to certain events.

Identification of extractable growth factors from small intestinal submucosa.

Abstract: When implanted as a biomaterial for tissue replacement, selected submucosal layers of porcine small intestine induce site-specific tissue remodeling. Small intestinal submucosa (SIS), as isolated, is primarily an acellular extracellular matrix mater~al. In an attempt to discover the components of small intestinal submucosa which are able to induce this tissue remodeling, the material was extracted and extracts were tested for the ability to stimulate Swiss 3T3 fibroblasts to synthesize DNA and proliferate. Each oi the iour different extracts of small intestinal submucosa had measurablecell-stimulating activity when analyzed in both a whole cell proliferation assay (alamarBlue dye reduction) and a DNA synthesis assay (('HI-thymidine incorporation). Proteins extracted from SIS with 2 M urea induced activity profiles in the two assays which were very similar to the activity profiles of basic fibroblast growth factor (FGF-2) in the assays. As well, the changes in cell morphology in response to the extracted proteins mimicked the changes induced by FGF-2. Neutralization experiments with specific antibodies to this growth factor confirmed the presence of FGF-2 and indicated that it was responsible for 60% oi the fibroblast-stimulating activity of the urea extract oi small intestinal submucosa. Western blot analvsis with a monoclonal antibody specific for FGF-2 detected a reactive doublet at approximately 19 kDa and further confirmed the presence oi FGF-2. Cell stimulat~ng activity oi proteins extracted irom SIS with 4 M guanidine was neutralized by an antibody specific ior transforming growth factor P CTCFB). Changes in the morphology oi the fibroblasts exposed to this extract were nearly identical to changes induced by TGFB. Although no reactive protein band was detected at 25 kDa in nonreduced western blot analysis, several bands were reactive at higher molecular weight. The identity of this TGFf3-related component of small intestinal submucosa is unknown. Identification of FGF-2 and TGFp-related activities in SIS, two growth tactors known to significantly affect critical processes oi tissue development and difierentiation, provides the opportunity to further elucidate the mechanisms by which this extracellu- larmatrix biomaterial modulates wound healing and tissueremodeling. J. Cell. Biochem. 67:478491,1997. Q 1997wik+~. ~nc