Cytotoxicity of bile in human Hep G2 cells and in primary cultures of rat hepatocytes

There has been increasing interest in the development of a hepatocyte bioreactor for the treatment of acute hepatic failure; however, little is known about the effect of hepatocyte byproducts on the viability of the cells in the bioreactor environment. We investigated the effects of increasing concentrations of bile on the growth and viability of the human hepatoma cell line Hep G2 and on the cytochrome P-450 content and dependent mixed function oxidase (MFO) activities, reduced glutathione (GSH) content, and glutathione S-transferase (GST) activity of primary cultures of rat hepatocytes. Our purpose was to determine whether or not it would be necessary to pretreat the plasma from patients with acute liver failure to remove elevated bile concentrations which might be toxic to the hepatocytes in an artificial liver device. Bile was found to inhibit Hep G2 cell growth at concentrations as low as 0.1% and to decrease viability at concentrations above 0.5%. The cytochrome P-450 and GSH contents and the activities of the MFO system and of GST were decreased in the primary cultures of hepatocytes following 24 h treatment with concentrations of bile at and above 0.5%. The MFO activities associated with different cytochrome P-450 isoenzymes decreased to different extents in the presence of bile with the O-dealkylation of pentoxyresorufin being more labile than that of ethoxyresorufin. Our data indicate that elevated bile concentrations are cytotoxic to liver cells, and it may be necessary to pretreat patient plasma to decrease its bile content to protect the cells during the clinical operation of a hepatocyte bioreactor device.     

The constitution of metastable titanium-rich Ti-Fe alloys:An order-disorder transition

Single phase Ti-Fe alloys with up to 50 at. pct Fe were prepared by splat cooling. Alloys with less than about 35 at. pct Fe consisted of β-titanium solid solution, designated Ti(Fe); alloys with more than 35 at. pct Fe consisted of a partially disordered, off-stoichiometric TiFe solid solution. The degree of order of this phase was determined. A continuous phase transition between the ordered and the disordered metastable phase is possible. The ordered metastable phase fulfills known valence electron concentration criteria for the occurrence of the CsCl structure type. Formally Research Assistant, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology, Cambridge, Mass. Formally Research Associate, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology,     

"Surprisingness" and short-term retention in pigeons.

Trained 14 Silver King pigeons in a symbolic matching-to-sample task in which food (access to grain) and no-food (blackout) samples were used. Responding to red test stimuli was reinforced on food sample trials, and responding to green test stimuli was reinforced on no-food sample trials. Samples of food and no food were rendered "expected" or "surprising" during subsequent testing by preceding samples with a previously established signal for either food (CS+) or no food (CS–). CS+ preceded food samples and CS– preceded no-food samples on surprising trials. Findings suggest that enhanced retention on surprising trials was apparent from the outset of testing to the extent that (a) surprising and expected trials were not markedly dissimilar to the trials of training, and (b) control over test responding by the CSs presented on expected and surprising trials was minimized. Results are discussed with regard to generalization decrement and directed remembering. It is concluded that surprising samples receive enhanced postperceptual processing and that the mechanism involved is that of retrieval-generated priming of short-term memory. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface chemical heterogeneity of bacteriogenic iron oxides from a subterranean environment

This study quantifies the surface chemical heterogeneity of bacteriogenic iron oxides (BIOS) and its end-members (2-line ferrihydrite and intermixed intact and fragmented bacteria). On a dry weight basis, BIOS consisted of 64.5 +/- 1.8% ferrihydrite and 34.5 +/- 1.8% organic matter. Enrichment of Al, Cu, Cr, Mn, Sr, and Zn was shown in the solid versus the aqueous phase (1.9 < log Kd < 4.2). Within the solid-phase Al (69.5%), Cu (78.7%), and Zn (77.9%) were associated with the bacteria, whereas Cr (59.8%), Mn (99.8%), and Sr (79.4%) preferred ferrihydrite. Acid-base titration data from the BIOS and bacteria were fitted using FOCUS pKa spectroscopy. The bacteria spectrum with pKa's of 4.18 +/- 0.37, 4.80 +/- 0.54, 6.98 +/- 0.45, and 9.75 +/- 0.68 was similar to discrete and continuous spectra for intact and fragmented bacteria. The BIOS spectrum recorded pKa's of 4.27 +/- 0.51, 6.61 +/- 0.51, 7.89 +/- 1.10, and 9.65 +/- 0.66 and was deconvoluted to remove overlapping binding site contributions from the bacteria. The resulting residual iron oxide spectrum coincided with discrete MUSIC spectra for goethite and lepidocrocite with pKa values of 4.10 +/- 0.43, 6.53 +/- 0.45, 7.81 +/- 0.76, and 9.51 +/- 0.68. Surface site density analysis showed that acidic sites (pKa < 6) were contributed by the bacteria (37%), whereas neutral sites (6 < pKa < 8) were characteristic of the iron oxide fraction (35%). Basic sites (8 < pKa) were higher in the bacteria (57%), than in the BIOS (44%) or iron oxide fractions (47%). This analysis suggested a high degree of bacterial group masking and a similarity between the BIOS and goethite surface reactivity. An understanding of the BIOS surface chemical heterogeneity and inherent proton and metal binding capacity was obtained through the use of FOCUS apparent pKa spectroscopy.     

A Review of the U.S. Department of Energy's Inertial Fusion Energy Program

This is the final report of a panel set up by the U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee (FESAC) in response to a charge letter from Dr. Ray Orbach (Appendix A). In that letter, Dr. Orbach asked FESAC for an assessment of the present status of inertial fusion energy (IFE) research carried out in contributing programs. These programs include the heavy ion (HI) beam, the high average power laser (HAPL), and Z-Pinch drivers and associated technologies, including fast ignition (FI). This report, presented to FESAC on March 29, 2004, and subsequently approved by them (Appendix B), presents FESAC's response to that charge.     

A Common Medium for Programming Operations-Research Models

Operations research is an interdisciplinary science that develops scientific methods for modeling and solving decision-making problems. Arguably, the two most established and commonly practiced OR methodologies are mathematical programming (also called optimization) and discrete-event system simulation (called simulation). Mathematical programming describes a decision problem as decision variables and as mathematical functions of variables that capture the objective and problem constraints. For dynamic systems that are too complex to allow exact, closed-form solutions in continuous time, simulation can identify and describe events of interest and model their occurrences at discrete points in time. Python can glue together independent software environments to improve the software development cycle for sophisticated operations-research applications, which integrate different modeling methodologies.     

Knowledge-driven multidimensional indexing structure for biomedical media database retrieval.

Today, biomedical media data are being generated at rates unimaginable only years ago. Content-based retrieval of biomedical media from large databases is becoming increasingly important to clinical, research, and educational communities. In this paper, we present the recently developed entropy balanced statistical (EBS) k-d tree and its applications to biomedical media, including a high-resolution computed tomography (HRCT) lung image database and the first real-time protein tertiary structure search engine. Our index utilizes statistical properties inherent in large-scale biomedical media databases for efficient and accurate searches. By applying concepts from pattern recognition and information theory, the EBS k-d tree is built through top-down decision tree induction. Experimentation shows similarity searches against a protein structure database of 53 363 structures consistently execute in less than 8.14 ms for the top 100 most similar structures. Additionally, we have shown improved retrieval precision over adaptive and statistical k-d trees. Retrieval precision of the EBS k-d tree is 81.6% for content-based retrieval of HRCT lung images and 94.9% at 10% recall for protein structure similarity search. The EBS k-d tree has enormous potential for use in biomedical applications embedded with ground-truth knowledge and multidimensional signatures.     

Evaluating the complementarity of acoustic and satellite remote sensing for seagrass landscape mapping

Accurate maps representing seagrass spatial distribution are essential components for effective monitoring and management of coastal vegetated habitats. Satellite and acoustic remote sensing provide valuable spatial data for seagrass mapping, though few studies have evaluated the complementarity of these methods. In this study, the complementarity of seagrass mapping was assessed through comparison of acoustic and satellite remote-sensing data sets. QuickBird^® satellite imagery representing the seagrass landscape of the Richibucto estuary, New Brunswick, Canada, was classified through an object-based procedure and evaluated against a single-beam sonar data set. Acoustic percentage cover values were classified into binary presence/absence format through the application of a decision threshold, allowing comparison with satellite data using the error matrix and derived metrics. Though the binary satellite classification resulted in relatively high accuracy compared with independent ground reference data, agreement between satellite and acoustic data sets was limited. Local differences in seagrass prevalence and patchiness affected classification accuracy, highlighting the potential for under- or overestimating seagrass cover when applying bay-scale classification to areas with different landscape structure. These results emphasize the importance of landscape context in seagrass mapping. Satellite and acoustic remote sensing were seen to fundamentally differ in their depiction of the landscape. Comparison of multiple remote-sensing methods allowed for assessment of complementarity as well as ecologically relevant insight to seagrass spatial dynamics, with implications for mapping and monitoring of seagrass habitats.