Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Transforming growth factors beta 1 and alpha in chronic liver disease : effects of interferon alfa therapy

Abstract: Background. Cirrhosis is a diffuse process of hepatic fibrosis and regenerative nodule formation of unknown pathogenesis. Transforming growth factor (TGF) β1 induces the production of extracellular matrix proteins by liver cells and has been implicated in the pathogenesis of hepatic fibrosis in laboratory animals. TGFα is a hepatocyte mitogen that participates in liver regeneration. Methods. Using Northern blot analysis, we studied the expression of TGFβ1 messenger RNA (mRNA) in liver specimens from 42 patients with chronic hepatitis and cirrhosis and 12 subjects with either normal or fatty livers. The results were correlated with measurements of procollagen Type I mRNA in liver tissue, procollagen Type III peptide in serum, and the degree of histologie injury. We also investigated whether TGFα mRNA would be detectable in biopsy specimens of livers with proliferative activity. Results. TGFβ1 mRNA expression correlated closely with the expression of procollagen Type I mRNA (r = 0.94) and serum pro...

Liquid-crystal materials find a new order in biomedical applications.

Abstract: With the maturation of the information display field, liquid-crystal materials research is undergoing a modern-day renaissance. Devices and configurations based on liquid-crystal materials are being developed for spectroscopy, imaging and microscopy, leading to new techniques for optically probing biological systems. Biosensors fabricated with liquid-crystal materials can allow label-free observations of biological phenomena. Liquid-crystal polymers are starting to be used in biomimicking colour-producing structures, lenses and muscle-like actuators. New areas of application in the realms of biology and medicine are stimulating innovation in basic and applied research into these materials.

Relative Cerebral Blood Volume Maps Corrected for Contrast Agent Extravasation Significantly Correlate with Glioma Tumor Grade, Whereas Uncorrected Maps Do Not

Abstract: METHODS: We performed dynamic T2*-weighted perfusion MR imaging on 43 patients with a cerebral glioma after prebolus gadolinium diethylene triamine penta-acetic acid administration to diminish competing extravasation-induced T1 effects. The rCBV was computed from non-necrotic enhancing tumor regions by integrating the relaxivity-time data, with and without contrast extravasation correction by using a linear fitting algorithm, and was normalized to contralateral brain. We determined the statistical correlation between corrected and uncorrected normalized rCBV and histopathologic tumor grade with the Spearman rank correlation test. RESULTS: Eleven, 9, and 23 patients had WHO grades II, III, and IV glioma, respectively. Mean uncorrected normalized rCBVs were 1.53, 2.51, and 2.14 (grade II, III, and IV). Corrected normalized rCBVs were 1.52, 2.84, and 3.96. Mean absolute discrepancies between uncorrected and corrected rCBVs were 2% (0%–15%), 16% (0%–106%), and 74% (0%–411%). The correlation between corrected rCBV and tumor grade was significant (0.60; P .0001), whereas it was not for uncorrected rCBV (0.15; P .35). CONCLUSION: For gliomas, rCBV estimation that correlates significantly with WHO tumor grade necessitates contrast extravasation correction. Without correction, artificially lowered rCBV may be construed erroneously to reflect lower tumor grade.

Lithium Diffusion in Graphitic Carbon

Abstract: Graphiticcarboniscurrentlyconsideredthestate-of-the-artmaterial for the negative electrode in lithium ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge/ discharge rate performance, which contributes to severe transport-induced sur- face structural damage upon prolonged cycling and limits the lifetime of the cell. Lithium bulkdiffusion in graphitic carbon is not yet completely understood, partly due to the complexity of measuring bulk transport properties in finite-sized nonisotropic particles. To solvethis problem forgraphite, weuse the Devanathan- Stachurski electrochemical methodology combined with ab initio computations to deconvolute and quantify the mechanism of lithium ion diffusion in highly oriented pyrolytic graphite (HOPG). The results reveal inherent high lithium ion diffusivityinthedirectionparalleltothegrapheneplane(∼10 -7 -10 -6 cm 2 s -1 ),as comparedtosluggishlithiumiontransportalonggrainboundaries(∼10 -11 cm 2 s -1 ), indicating the possibility of rational design of carbonaceous materials and com- posite electrodes with very high rate capability. SECTION Energy Conversion and Storage

Estimating sleep patterns with activity monitoring in children and adolescents: how many nights are necessary for reliable measures?

Abstract: Study Objectives: This study provides estimates of reliability for aggregated values from 1 to 7 recording nights for five commonly used actigraphic measures of sleep patterns, reliability as a function of night type (weeknight or weekend night), and stability of measures over several months. Design and Setting: Data are from three studies that obtained 7 nights of actigraph data (using Mini Motionlogger actigraphs and associated validated algorithms [ASA]) on children and adolescents living at home on self-selected sleep-wake schedules. Participants: Participants were 169 children aged 12-60 months, and 55 adolescents aged 11-16 years. Measurements and Results: Up to 28% of weekly recordings may be unacceptable for analysis in young participants because of illness, technical problems, and participant noncompliance; studies aiming to collect 5 nights of actigraph data should record for at least 1 full week. Reliability estimates for values aggregated over any 5 nights were adequate (≥.70) for sleep start time, wake minutes, and sleep efficiency. Measures of sleep minutes and sleep period were less reliable and may require 7 or more nights for estimates of stable individual differences. Reliability for 1- or 2-night aggregates were poor for all measures. We found significant and high correlations between summer and fall session measures for all five variables when weekend nights were included. Conclusions: Five or more nights of usable recordings are required to obtain reliable actigraph measures of sleep for chil