Traffic Noise and Inequality in the Twin Cities,Minnesota

It is widely known that prolonged exposure to high levels of traffic noise has several health effects. While scholarship in environmental justice has explored the environmental equity hypothesis in a wide range of areas, whether the spatial distribution of traffic noise is equitable among different racial and socioeconomic groups has rarely been explored, especially in the United States. This article addresses this lacuna by examining this relationship in the Twin Cities Metro Region, Minnesota. Traffic data from the Minnesota Department of Transportation were used to model the propagation of traffic noise over the study area and aircraft noise contour lines were added to account for aircraft noise. Inequities associated with exposure to chronic traffic noise were investigated using selected demographic and socioeconomic variables from the U.S. Census 2000. Statistical analysis was based on a regression model that addressed spatial autocorrelation. Results indicate that there is an association between noise levels and household income, median household value, the percentage of non-white residents, and the percentage of the population less than 18 years of age.     

Water transport in the arterial wall--a theoretical study

Water transport in the arterial wall is studied using a mathematical model based on the theory for the consolidation of water saturated soils (Biot, 1941; Kenyon, 1976a). The intimal pressure is considered to be harmonic in time. Analytical results are obtained for both large and small consolidation times since both the situations are of physiological relevance. For large consolidation times, the filtration is confined to a thin boundary layer. Large pressure gradients exist within the boundary layer while the pressure gradient is negligible in the intermediate layer. Thus, the pulsatile flow is found to be confined to the boundary layer while a smaller mean flow exists throughout the wall.     

Indole is an inter-species biofilm signal mediated by SdiA

Background  

As a stationary phase signal, indole is secreted in large quantities into rich medium by Escherichia coli and has been shown to control several genes (e.g., astD, tnaB, gabT), multi-drug exporters, and the pathogenicity island of E. coli; however, its impact on biofilm formation has not been well-studied.     

Characterization of 1,3-propanediol oxidoreductase (DhaT) from <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> J2B

1,3-propanediol oxidoreductase (DhaT) of Klebsiella pneumoniae converts 3-hydroxypropionaldehyde (3-HPA) to 1,3-propanediol (1,3-PD) during microbial production of 1,3-PD from glycerol. In this study, DhaT from newly isolated K. pneumoniae J2B was cloned, expressed, purified, and studied for its kinetic properties. It showed, on its physiological substrate 3-HPA, higher activity than similar aldehydes such as acetaldehyde, propionaldehyde and butyraldehyde. The turnover numbers (k _cat , 1/s) were estimated as 59.4 for the forward reaction (3-HPA to 1,3-PD at pH 7.0) and 10.0 for the reverse reaction (1,3-PD to 3-HPA at pH 9.0). The Michaelis constants (K _m , mM) were 0.77 (for 3-HPA) and 0.03 (for NADH) for the forward reaction (at pH 7.0), and 7.44 (for 1,3-PD) and 0.23 (for NAD⁺) for the reverse reaction (at pH 9.0). Between these forward and reverse reactions, the optimum temperature and pH were significantly different (37°C and 7.0 vs. 55°C and 9.0, respectively). These results indicate that, under physiological conditions, DhaT mostly catalyzes the forward reaction. The enzyme was seriously inhibited by heavy metal ions such as Ag⁺ and Hg²⁺. DhaT was highly unstable when incubated with its own substrate 3-HPA, indicating the necessity of enhancing its stability for improved 1,3-PD production from glycerol.     

Human retinoblastoma binding protein 9, a serine hydrolase implicated in pancreatic cancers

Human retinoblastoma binding protein 9 (RBBP9) is an interacting partner of the retinoblastoma susceptibility protein (Rb). RBBP9 is a tumor-associated protein required for pancreatic neoplasia, affects cell cycle control, and is involved in the TGF-β signalling pathway. Sequence analysis suggests that RBBP9 belongs to the α/β hydrolase superfamily of enzymes. The serine hydrolase activity of RBBP9 is required for development of pancreatic carcinomas in part by inhibiting TGF-β antiproliferative signaling through suppressing Smad2/3 phosphorylation. The crystal structure of human RBBP9 confirms the α/β hydrolase fold, with a six-stranded parallel β-sheet flanked by α helixes. The structure of RBBP9 resembles that of the YdeN protein from Bacillus subtilis, which is suggested to have carboxylesterase activity. RBBP9 contains a Ser75-His165-Asp138 catalytic triad, situated in a prominent pocket on the surface of the protein. The side chains of the LxCxE sequence motif that is important for interaction with Rb is mostly buried in the structure. Structure- function studies of RBBP9 suggest possible routes for novel cancer drug discovery programs.     

Lymphocyte toxicity of prion fragments

Prion protein fragments that are extracted from the brains of patients with Gerstmann-Straussler-Scheinker disease are known to have stimulating action on circulating leukocytes. In particular, the amyloidogenic hydrophobic prion peptide HuPrP (113-127) AGAAAAGAVVGGLGG has been reported to be associated with significant cellular toxicity. In this paper we show that the self assembled form of HuPrP (113-127) and its valine rich domains viz. GAVVGGLG [HuPrP (119-126)] and VVGGLGG [HuPrP (121-127)] are toxic to peripheral lymphocytes. To explore the cytotoxic mechanism of these fragments, we studied 3-(4,5-dimethylthiazol-2yl)-2-5-diphenyltetrazolium bromide (MTT) reduction, reactive oxygen species (ROS) generation, calcium influx and raft sequestration of' peptide treated lymphocytes. Langmuir monolayer studies on these peptides showed a maximum lipid perturbing property of HuPrP (121-127) as compared to the other two fragments. MTT reduction assays on lymphocytes treated with peptides indicated that the prion peptide fibrils are relatively more toxic than freshly solubilized peptide preparations. Lymphocytes treated with HuPrP (121-127), HuPrP (113-127) and HuPrP (119-126) fibrils underwent 60%, 30% and 40% cell death, respectively. Abeta(1-42), HuPrP (119-126) and HuPrP (121-127) fibrils caused 4 fold increases in intracellular ROS as compared with control cells. However, HuPrP (113-127) fibrils lacked such a significant ROS generating activity, indicating that a subtle difference in sequence leads to a difference in the toxic mechanism in the cell. HuPrP (119-126) and HuPrP (121-127) fibrils also produced maximum raft sequestration and calcium influx. Taken together, these data suggest that the assemblage of prion fragments has significant toxic activity on peripheral lymphocytes, a finding with implications for controlling reactive lymphocytes in prion infected subjects.     

Exploring the environmental preference of weak interactions in (alpha/beta)8 barrel proteins

The environmental preference for the occurrence of noncanonical hydrogen bonding and cation-pi interactions, in a data set containing 71 nonredundant (alpha/beta)(8) barrel proteins, with respect to amino acid type, secondary structure, solvent accessibility, and stabilizing residues has been performed. Our analysis reveals some important findings, which include (a) higher contribution of weak interactions mediated by main-chain atoms irrespective of the amino acids involved; (b) domination of the aromatic amino acids among interactions involving side-chain atoms; (c) involvement of strands as the principal secondary structural unit, accommodating cross strand ion pair interaction and clustering of aromatic amino acid residues; (d) significant contribution to weak interactions occur in the solvent exposed areas of the protein; (e) majority of the interactions involve long-range contacts; (f) the preference of Arg is higher than Lys to form cation-pi interaction; and (g) probability of theoretically predicted stabilizing amino acid residues involved in weak interaction is higher for polar amino acids such as Trp, Glu, and Gln. On the whole, the present study reveals that the weak interactions contribute to the global stability of (alpha/beta)(8) TIM-barrel proteins in an environment-specific manner, which can possibly be exploited for protein engineering applications.     

Evaluation of alpha-D-mannopyranoside glycolipid micelles-lectin interactions by surface plasmon resonance method

It is established that achieving higher binding affinities in carbohydrate-protein interactions requires multivalent presentations of the sugar ligands at the receptor binding site. Several inhibition, calorimetric, mass balance, and other studies have reiterated the beneficial effects of molecular level clustering of the sugar ligands for tight binding to the receptors. We have undertaken an effort to study the multivalent effects involving larger assemblies, represented by micelles, and their lectin interactions. The micelles were constituted with monomer bearing one- or two-sugar moieties at the monomolecular level and with varying the distances between the sugar moieties. Micellar aggregation studies and dynamic light scattering (DLS) studies afforded details of the aggregation numbers and the hydrodynamic diameters of various glycolipid (GL) micelles. The GL micelles were used as analytes of surface plasmon resonance (SPR) experiments on a lectin concanavalin A (Con A)-immobilized surface. SPR studies of the micelle-lectin interactions demonstrate that the ligand-receptor binding can be fit into the bivalent analyte model of interaction. Furthermore, micelles formed from two-sugar containing GLs are able to elicit favorable kinetic association rate constants in comparison to the micelles constituted with one-sugar containing GLs. The kinetic rate constants across the micelles and the effect of the sugar valencies in the GLs are discussed.