Rebamipide abolishes Helicobacter pylori CagA-induced phospholipase D1 expression via inhibition of NFκB and suppresses invasion of gastric cancer cells.

Infection with cagA-positive Helicobacter pylori is a risk factor for the development of severe gastritis and gastric cancer (GC). CagA protein is injected into gastric epithelial cells and deregulates a variety of cellular signaling molecules. Phospholipase D (PLD) is elevated in many different types of human cancers and has been implicated as a critical factor in inflammation and carcinogenesis. In this study, we show that infection with cagA-positive H. pylori in GC cells significantly induces PLD1 expression via CagA-dependent activation of nuclear factor κB (NFκB). Interestingly, the level of PLD1 protein and IκBα phosphorylation is aberrantly upregulated in H. pylori-infected human GC tissues. Infection with cagA-positive H. pylori and expression of CagA enhanced the binding of NFκB to the PLD1 promoter, and two functional NFκB-binding sites were identified within the PLD1 promoter. Rebamipide, a mucosal-protective antiulcer agent, abolished H. pylori cagA-induced PLD1 expression via inhibition of binding of NFκB to the PLD1 promoter, and also inhibited PLD activity. Moreover, rebamipide suppressed H. pylori-induced matrix metalloproteinase-9, interleukin-8 and activation-induced cytidine deaminase expression as well as invasion of GC cells through downregulation of PLD1. Our data suggest that H. pylori cagA targets PLD1 for invasion of GC cells, and rebamipide might contribute to the antitumorigenic effect of GC cells via inhibition of the H. pylori cagA-NFκB-PLD1 signaling pathway.

Identification of information flow-modulating drug targets: a novel bridging paradigm for drug discovery.

Our objective in this study was to identify novel metrics for efficient identification of drug targets using biological network topology data. We developed a novel paradigm and metric, namely, bridging centrality, capable of identifying nodes critically involved in connecting or bridging modular subregions of a network. The topological and biological characteristics of bridging nodes were delineated in a diverse group of published yeast networks and in three human networks: those involved in cardiac arrest, C21-steroid hormone biosynthesis, and steroid biosynthesis. The bridging centrality metric was highly selective for bridging nodes. Bridging nodes differed distinctively from nodes with high degree and betweenness centrality. Bridging nodes had lower lethality, and their gene expression was consistent with independent regulation. Analysis of biological correlates indicated that bridging nodes are promising drug targets from the standpoints of efficacy and side effects. The bridging centrality method is a promising computational systems biology tool to aid target identification in drug discovery.

Membrane instability in late-stage erythropoiesis.

During maturation of the red blood cell (RBC) from the nucleated normoblast stage to the mature biconcave discocyte, both the structure and mechanical properties of the cell undergo radical changes. The development of the mechanical stability of the membrane reflects underlying changes in the organization of membrane-associated cytoskeletal proteins, and so provides an assessment of the time course of the development of membrane structural organization. Membrane stability in maturing erythrocytes was assessed by measuring forces required to form thin, tubular, lipid strands (tethers) from the surfaces of mononuclear cells obtained from fresh human marrow samples, marrow reticulocytes, circulating reticulocytes, and mature erythrocytes. Cells were biotinylated and manipulated with a micropipette to form an adhesive contact with a glass microcantilever, which gave a measure of the tethering force. The cell was withdrawn at controlled velocity and aspiration pressure to form a tether from the cell surface. The mean force required to form tethers from marrow reticulocytes and normoblasts was 27 +/- 9 pN, compared to 54 +/- 14 pN for mature cells. The energy of dissociation of the bilayer from the underlying skeleton increases 4-fold between the marrow reticulocyte stage and the mature cell, demonstrating that the mechanical stability of the membrane is not completely established until the very last stages of RBC maturation.

Psychosocial predictors of first-onset depression in Chinese Americans.

BACKGROUND: This study examines the longitudinal and concurrent risk factors associated with first-onset major depression in a community sample of 1747 Chinese Americans in Los Angeles. METHODS: The relative contributions of demographic, health, psychiatric, psychosocial, and cultural variables were assessed in a series of longitudinal and concurrent hierarchical multivariable analyses. RESULTS: Results of the longitudinal analyses indicated that the risk for experiencing a first major depressive episode at 18-months follow-up was higher for those who initially rated their health as poor, reported higher depressive symptoms, and perceived higher levels of social support. After controlling for prior health and psychiatric and psychosocial status at time 1, the results of the concurrent analyses indicated that the risk for experiencing a first major depressive episode at time 2 was higher for those who rated their health as poor, had at least one other psychiatric disorder, were bilingual, experienced high levels of life stress, and perceived themselves as having low and/or decreased social supports. CONCLUSIONS: The results of this study confirm previous evidence that psychosocial vulnerabilities, including higher acculturation, greater stress exposure and reduced social supports, are important predictors of risk for first-onset depressive episodes. Prevention and treatment implications are addressed, and future directions for research are offered.

Role of the working alliance in the treatment of delinquent boys in community-based programs.

Examined the role of the working alliance in the treatment of delinquent boys in community-based residential programs, clarifying the relation between therapeutic process and behavioral change. Horvath and Greenberg's (1989) Working Alliance Inventory was used to assess the therapeutic alliance between youth and staff after 3 weeks in treatment and again after 3 months. Achenbach's (1991) Child Behavior Checklist (CBCL; Youth Self-Report [YSR] and Teacher Report Form [TRF]) and recidivism scores were used to assess treatment progress and outcome. Results indicated that a positive working alliance assessed after 3 months in treatment related to positive psychological changes and predicted lower rates of recidivism. Unexpectedly, a positive working alliance assessed early in treatment was associated with negative outcomes (increased internalizing and externalizing symptoms and higher rates of recidivism). This finding suggests that for some delinquent youth initially optimistic assessments may be prognostic of slow progress or treatment failure.

Energy of dissociation of lipid bilayer from the membrane skeleton of red blood cells.

The association between the lipid bilayer and the membrane skeleton is important to cell function. In red blood cells, defects in this association can lead to various forms of hemolytic anemia. Although proteins involved in this association have been well characterized biochemically, the physical strength of this association is only beginning to be studied. Formation of a small cylindrical strand of membrane material (tether) from the membrane involves separation of the lipid bilayer from the membrane skeleton. By measuring the force required to form a tether, and knowing the contribution to the force due to the deformation of a lipid bilayer, it is possible to calculate the additional contribution to the work of tether formation due to the separation of membrane skeleton from the lipid bilayer. In the present study, we measured the tethering force during tether formation using a microcantilever (a thin, flexible glass fiber) as a force transducer. Numerical calculations of the red cell contour were performed to examine how the shape of the contour affects the calculation of tether radius, and subsequently separation work per unit area W(sk) and bending stiffness k(c). At high aspiration pressure and small external force, the red cell contour can be accurately modeled as a sphere, but at low aspiration pressure and large external force, the contour deviates from a sphere and may affect the calculation. Based on an energy balance and numerical calculations of the cell contour, values of the membrane bending stiffness k(c) = 2.0 x 10(-19) Nm and the separation work per unit area W(sk) = 0.06 mJ/m2 were obtained.

Combined use of fluorescence microscopy and micromechanical measurement to assess cell and membrane properties.

The combined use of fluorescence microscopy and micromanipulation provides a powerful approach for understanding the mechanochemistry of cell membranes. Fluorescent labeling of erythrocytes has been used to identify particular populations of cells to assess the effects of abnormal deformability on cell survival. It was found that cells deprived of surface area are either eliminated rapidly from the circulation or undergo a reduction in volume to improve cellular deformability. Fluorescence microscopy can also be used to assess the distribution of specific membrane components during mechanical deformation and fragmentation of cell membranes and so lead to more fundamental understanding of the physical association between the membrane bilayer and the underlying membrane cytoskeleton.

Detection of cadmium electrode surfaces using cw and pulsed radiation.

Simultaneous in situ photoacoustic, photoconductive, and electrochemical detection of species at the surface of the cadmium electrode has been demonstrated using both cw and pulsed light sources. The advantages of the cw and pulsed photoacoustic techniques were evaluated. Both techniques were applied to study the passivation of the cadmium electrode on high rate discharge. Cadmium oxide was identified on the electrode after passivation.