University of Arkansas for Medical Sciences

About: University of Arkansas for Medical Sciences is a education organization based out in Little Rock, Arkansas, United States. It is known for research contribution in the topics: Population & Health care. The organization has 14077 authors who have published 26012 publications receiving 973592 citations. The organization is also known as: UAMS.

Chordoma and chondrosarcoma: Similar, but quite different, skull base tumors

Abstract: BACKGROUND Chordoma and chondrosarcoma of the skull base are frequently amalgamated because of similar anatomic location, clinical presentation, and radiologic findings. The chondroid chordoma variant has been reported to carry a better prognosis. The objective of the current study was to investigate the distinctions between these 3 entities. METHODS The data concerning 109 patients with chordoma, chondroid chordoma, and chondrosarcoma who were treated by a single surgeon with maximum surgical resection and frequently by adjunct proton beam radiotherapy between 1990 and 2006 were analyzed retrospectively. Pathologic distinction was established by cytokeratin and epithelial membrane antigen staining. Clinical, radiologic, pathologic, and cytogenetic studies were analyzed in relation to disease recurrence and death. RESULTS The average follow-up was 48 ± 37.5 months (range, 1–191 months). There were no reliable distinguishing clinical or radiologic features noted between the groups. Chondrosarcoma patients had a significantly better outcome compared with chordoma patients with regard to survival and recurrence-free survival (P = .028 and P < .001, respectively), whereas patients with chondroid chordoma had a poor outcome similar to chordoma patients with regard to survival and recurrence-free survival (P = .337 and P = .906, respectively). CONCLUSIONS Chordoma and chondrosarcoma differ with regard to their origin and histology, and differ markedly with regard to outcome. Chondroid chordomas behave in a manner that is clinically similar to chordomas, with the same prognosis. Both chordoma types demonstrate an aggressive clinical course and poor outcome after disease recurrence. The optimal treatment for all groups of patients involves radical surgical resection followed by high-dose radiotherapy in patients with chordomas. Radiotherapy may not be necessary in patients with low-grade chondrosarcoma. Cancer 2007. © 2007 American Cancer Society.

MRI evaluation of basal ganglia ferritin iron and neurotoxicity in Alzheimer's and Huntingon's disease.

Abstract: BACKGROUND The basal ganglia contain the highest levels of iron in the brain and post-mortem studies indicate a disruption of iron metabolism in the basal ganglia of patients with neurodegenerative disorders such as Alzheimer's disease (AD) and Huntington's disease (HD). Iron can catalyze free radical reactions and may contribute to oxidative damage observed in AD and HD brain. Magnetic resonance imaging (MRI) can quantify transverse relaxation rates, which can be used to quantify tissue iron stores as well as evaluate increases in MR-visible water (an indicator of tissue damage). METHODS A magnetic resonance imaging (MRI) method termed the field dependent relaxation rate increase (FDRI) was employed which quantifies the iron content of ferritin molecules (ferritin iron) with specificity through the combined use of high and low field-strength MRI instruments. Three basal ganglia structures (caudate, putamen and globus pallidus) and one comparison region (frontal lobe white matter) were evaluated. Thirty-one patients with AD and a group of 68 older control subjects, and 11 patients with HD and a group of 27 adult controls participated (4 subjects overlap between AD and HD controls). RESULTS Compared to their respective normal control groups, increases in basal ganglia FDRI levels were seen in both AD and HD. FDRI levels were significantly increased in the caudate (p = 0.007) and putamen (p = 0.008) of patients with AD with a trend toward an increase in the globus pallidus (p = 0.13). In the patients with HD, all three basal ganglia regions showed highly significant FDRI increases (p<0.001) and the magnitude of the increases were 2 to 3 times larger than those observed in AD versus control group comparison. For both HD andAD subjects, the basal ganglia FDRI increase was not a generalized phenomenon, as frontal lobe white matter FDRI levels were decreased in HD (p = 0.015) and remained unchanged in AD. Significant low field relaxation rate decreases (suggestive of increased MR-visible water and indicative of tissue damage) were seen in the frontal lobe white matter of both HD and AD but only the HD basal ganglia showed such decreases. CONCLUSIONS The data suggest that basal ganglia ferritin iron is increased in HD and AD. Furthermore, the increased iron levels do not appear to be a byproduct of the illness itself since they seem to be present at the onset of the diseases, and thus may be considered a putative risk factor. Published post-mortem studies suggest that the increase in basal ganglia ferritin iron may occur through different mechanisms in HD and AD. Consistent with the known severe basal ganglia damage, only HD basal ganglia demonstrated significant decreases in low field relaxation rates. MRI can be used to dissect differences in tissue characteristics, such as ferritin iron and MR-visible water, and thus could help clarify neuropathologic processes in vivo. Interventions aimed at decreasing brain iron levels, as well as reducing the oxidative stress associated with increased iron levels, may offer novel ways to delay the rate of progression and possibly defer the onset of AD and HD.

Staphylococcus aureus AgrA Binding to the RNAIII-agr Regulatory Region

Abstract: The control of virulence gene expression in the human pathogen Staphylococcus aureus is under the partial control of the two-component quorum-sensing system encoded by genes of the agr locus. The product of the agrA gene has been shown by amino acid sequence similarity to be the putative response regulator; however, binding of AgrA to promoters under its control has not yet been demonstrated. In this study, we isolated and purified soluble AgrA by expression under osmotic shock conditions and ion-exchange chromatography. Purified AgrA showed high-affinity binding to the RNAIII-agr intergenic region by electrophoretic mobility shift assays. Binding was localized by DNase I protection assays to a pair of direct repeats in the P2 and P3 promoter regions of the agr locus. We found that this binding was enhanced by the addition of the small phosphoryl donor, acetyl phosphate. The difference in binding affinity between these two promoters was found to result from a 2-bp difference between the downstream direct repeats of the P2 and P3 sites. Mutation of these base pairs in the P3 site to match those found in the P2 site increased the affinity of AgrA for the P3 site relative to that for the P2 site. These results are consistent with the function of AgrA as a response regulator with recognition sites in the promoter regions of RNAIII and the agr locus.

Rural‐Urban Differences in Stigma and the Use of Care for Depressive Disorders

Abstract: Stigma may be a particularly important barrier to mental health care in rural communities where lack of anonymity increases the probability that someone who seeks care will be labeled "crazy." This study examined rural-urban differences in the stigma associated with depressive symptoms and the stigma associated with seeking treatment for depressive disorders. In addition, the study compared how the stigma associated with seeking treatment predicted use of care in rural and urban residents with a history of depressive symptoms. Two hundred subjects from metropolitan and adjacent non-metropolitan counties rated one of four randomly selected vignettes using 14-point semantic differential scales. The findings indicated that rural residents with a history of depressive symptoms labeled people who sought professional help for the disorder somewhat more negatively than their urban counterparts. Logistic models controlling for sociodemographic characteristics demonstrated that the more negative the labeling, the less likely depressed rural residents were to have sought professional help. Labeling was not associated with use of care among urban people with depressive symptoms. We concluded that prospective studies are warranted to inform the development of interventions to decrease the stigma associated with seeking treatment for depressive disorders in rural communities.