Synthesis and biological activity of 4-alkoxy chalcones: potential hydrophobic modulators of P-glycoprotein-mediated multidrug resistance

A series of 4-alkoxy-2′,4′,6′-trihydroxychalcones have been synthesized and evaluated for their ability to inhibit P-glycoprotein-mediated multidrug resistance (MDR) by direct binding to a purified protein domain containing an ATP-binding site and a modulator-interacting region. The introduction of hydrophobic alkoxy goups at position 4 led to much more active compounds as compared to the parent chalcone. The binding affinity increased as a function of the chain length, up to the octyloxy derivative for which a K_D of 20 nM was obtained.     

Effect of the H, K-ATPase inhibitor, esomeprazole magnesium, on gut total antioxidant capacity in mice

Antioxidant depletion is believed to be a mechanism involved in the pathophysiology of several upper gastrointestinal disorders, and H, K-ATPase inhibitors can alter free radical production by neutrophils. We hypothesized that the H, K-ATPase inhibitor esomeprazole magnesium would decrease gut free radical production with a concomitant increase in gut total antioxidant capacity. A/J mice (n = 10/group) received either vehicle (control) or one of three concentrations of esomeprazole magnesium in vehicle by once-daily gavage for 10 days. Using tissue extracts from stomach and colon, total antioxidant capacity, lipid peroxide levels, and constitutive Cu/Zn-superoxide dismutase were measured using validated assays. There was a dose-related increase in total antioxidant capacity (analysis of variance, P < 0.001) in stomach, but there was no change in the colon. In the assessment of free radical production, there was a trend toward decreased lipid peroxide levels in stomach from mice receiving esomeprazole. In stomach, Cu/Zn-superoxide dismutase activity was increased (ANOVA: p=.03) in mice receiving esomeprazole. In conclusion, gastric total antioxidant capacity and Cu/Zn-superoxide dismutase activity are increased by esomeprazole, and these changes may result in part from decreased free radical production. The present results support the notion that the pharmacological effects of this agent on upper intestinal tissue are more complex than previously thought, and appear to involve both enzymatic and nonenzymatic tissue antioxidants.     

IFN-alpha and IL-12 induce IL-18 receptor gene expression in human NK and T cells

IL-18 is a proinflammatory cytokine that enhances innate and specific Th1 immune responses. During microbial infections, IL-18 is produced by activated macrophages. IL-18 exerts its effects in synergy with IFN-alpha or IL-12 to induce IFN-gamma. Here we show that in human NK and T cells IFN-alpha and IL-12 strongly up-regulate mRNA expression of the IL-18R components, accessory protein-like (AcPL) and IL-1R-related protein (IL-1Rrp). In addition, IFN-alpha enhanced the expression of MyD88, an adaptor molecule involved in IL-18 signaling. Pretreatment of T cells with IFN-alpha or IL-12 enhanced IL-18-induced NF-kappaB activation and sensitized the cells to respond to lower concentrations of IL-18. AcPL and IL-1Rrp genes were strongly expressed in T cells polarized with IL-12, whereas in IL-4-polarized cells these genes were expressed at very low levels, indicating that AcPL and IL-1Rrp genes are preferentially expressed in Th1 cells. In conclusion, the results suggest that IFN-alpha and IL-12 enhance innate as well as Th1 immune response by inducing IL-18R expression.     

Characterization of articular cartilage by combining microscopic analysis with a fibril-reinforced finite-element model

Load-bearing characteristics of articular cartilage are impaired during tissue degeneration. Quantitative microscopy enables in vitro investigation of cartilage structure but determination of tissue functional properties necessitates experimental mechanical testing. The fibril-reinforced poroviscoelastic (FRPVE) model has been used successfully for estimation of cartilage mechanical properties. The model includes realistic collagen network architecture, as shown by microscopic imaging techniques. The aim of the present study was to investigate the relationships between the cartilage proteoglycan (PG) and collagen content as assessed by quantitative microscopic findings, and model-based mechanical parameters of the tissue. Site-specific variation of the collagen network moduli, PG matrix modulus and permeability was analyzed. Cylindrical cartilage samples (n=22) were harvested from various sites of the bovine knee and shoulder joints. Collagen orientation, as quantitated by polarized light microscopy, was incorporated into the finite-element model. Stepwise stress-relaxation experiments in unconfined compression were conducted for the samples, and sample-specific models were fitted to the experimental data in order to determine values of the model parameters. For comparison, Fourier transform infrared imaging and digital densitometry were used for the determination of collagen and PG content in the same samples, respectively. The initial and strain-dependent fibril network moduli as well as the initial permeability correlated significantly with the tissue collagen content. The equilibrium Young's modulus of the nonfibrillar matrix and the strain dependency of permeability were significantly associated with the tissue PG content. The present study demonstrates that modern quantitative microscopic methods in combination with the FRPVE model are feasible methods to characterize the structure-function relationships of articular cartilage.     

Decreased anthocyanidin reductase expression strongly decreases silver birch (Betula pendula) growth and alters accumulation of phenolics

Phenolics, formed via a complex phenylpropanoid pathway, are important defensive agents in plants and are strongly affected by nitrogen (N) fertilization. Proanthocyanidins (PAs) are one possible endpoint of the phenylpropanoid pathway, and anthocyanidin reductase (ANR) represents a key enzyme in PA biosynthesis. In this study, the expression of silver birch (Betula pendula) anthocyanidin reductase BpANR was inhibited using the RNA interference (RNAi) method, in three consequent BpANR RNAi (ANRi birches) lines. The growth, the metabolites of the phenylpropanoid pathway, and the number of resin glands of the ANRi birches were studied when grown at two N levels. ANRi birches showed decreased growth and reduction in PA content, while the accumulation of total phenolics in both stems and leaves increased. Moreover, ANRi birches produced more resin glands than did wild‐type (WT) birches. The response of ANRi birches to N depletion varied compared with that of WT birches, and in particular, the concentrations of some phenolics in stems increased in WT birches and decreased in ANRi birches. Because the inhibition of PAs biosynthesis via ANR seriously affected birch growth and resulted in accumulation of the precursors, the native level of PAs in plant tissues is assumed to be the prerequisite for normal plant growth. This draws attention to the real plant developmental importance of PAs in plant tissues.     

Severe acute respiratory syndrome coronavirus fails to activate cytokine-mediated innate immune responses in cultured human monocyte-derived dendritic cells

Activation of host innate immune responses was studied in severe acute respiratory syndrome coronavirus (SCV)-infected human A549 lung epithelial cells, macrophages, and dendritic cells (DCs). In all cell types, SCV-specific subgenomic mRNAs were seen, whereas no expression of SCV proteins was found. No induction of cytokine genes (alpha interferon [IFN-alpha], IFN-beta, interleukin-28A/B [IL-28A/B], IL-29, tumor necrosis factor alpha, CCL5, or CXCL10) or IFN-alpha/beta-induced MxA gene was seen in SCV-infected A549 cells, macrophages, or DCs. SCV also failed to induce DC maturation (CD86 expression) or enhance major histocompatibility complex class II expression. Our data strongly suggest that SCV fails to activate host cell cytokine gene expression in human macrophages and DCs.     

Biological threat characterization research: a critical component of national biodefense

Biological warfare (BW) threat assessments identify and prioritize BW threats to civilian and military populations. In an ideal world, they provide policymakers with clear and compelling guidance to prioritize biodefense research, development, testing, evaluation, and acquisition of countermeasures. Unfortunately, the biodefense community does not exist in an ideal world. National security professionals responsible for crafting BW threat assessments often are challenged by factors that limit the clarity and/or timeliness of those assessments. Moreover, the potential for life science advances to enhance threats enabled by state programs and the possibility that non-state actors may pursue crude but effective BW methodologies will drastically expand the scope of the perceived threat. Appropriate investment of federal biodefense funds will require some mechanism for validating and prioritizing present and future threats. Ideally, such a mechanism will incorporate empirical data targeted to elucidate actual hazards. In this regard, the Department of Homeland Security's creation of a Biological Threat Characterization Program for the technical validation of threat agents will be a valuable addition to the nation's overall biodefense strategy. This article articulates the need for a coordinated national biological threat characterization program, discusses some of the principal challenges associated with such research, and suggests a few options for their resolution.