Thiophene containing triarylmethanes as antitubercular agents

A new series of thiophene containing triarylmethane derivatives were synthesized from the Friedel-Crafts alkylation of diarylcarbinols followed by incorporation of amino alkyl chains. These were evaluated against Mycobacterium tuberculosis H37R(v) and showed the activity in the range of 3.12-12.5 microg/mL in vitro.     

Synthesis and evaluation of antitubercular activity of glycosyl thio- and sulfonyl acetamide derivatives

A series of glycosyl thioacetamide and glycosyl sulfonyl acetamide derivatives have been prepared following a convenient reaction protocol and evaluated for their antitubercular activity against Mycobacterium tuberculosis H₃₇Rv. Amongst 32 compounds evaluated 3 compounds were effective in inhibiting mycobacterial growth at MIC of 6.25 μg/mL, 6 compounds at MIC of 3.125 μg/mL and 1 compound at MIC of 1.56 μg/mL. All active compounds were found nontoxic in Vero cell lines and mice bone marrow macrophages.     

Effects of thyroid status on arginine vasotocin receptor VT2R expression and adrenal function in osmotically stimulated domestic fowl

The role of thyroid hormones in the regulation of adrenal function during stress has been documented in mammals, but only limited reports are available in avian species. The present study was undertaken to analyze the effect of hyper- or hypothyroidism on the adrenal activity under control (hydrated) and osmotically stressed (water deprived, WD) conditions, with special emphasis on the expression of arginine vasotocin receptor VT2 (VT2R) in pituitary corticotrophs. Chickens were made hyper- or hypothyroidic by injecting thyroxine (T4) and 2-thiouracil (TU), respectively for 14 days. After 10 days of injections, one sub-group of both, T4- or TU-treated chickens were subjected to osmotic stress by water deprivation. Hyperthyroidism stimulated adrenal steroidogenic activity compared to euthyroid control birds, but no change was observed in the expression of VT2R. On the other hand, TU-induced hypothyroidism however showed no effect on adrenal gland, but a significant increase in the expression of VT2R was observed. Neither hyper- nor hypothyroidism altered pro-opiomelanocortin (POMC) mRNA levels. Following osmotic stress, no effect was observed either on the adrenal gland or on the VT2R expression in hyperthyroidic birds, but in hypothyroidic birds, osmotic stress stimulated adrenal steroidogenic activity and decreased VT2R expression in comparison to its respective controls (T4 or TU). Expression of POMC mRNA was again unaltered following osmotic stress. Although exact mechanism is not clear, the data indicate that high plasma T4 level stimulates adrenal activity and may also modulate function of the pituitary–adrenal axis during dehydration.     

Selenium supplementation influences growth performance, antioxidant status and immune response in lambs

To investigate and compare the effect of inorganic and organic Se supplementation, 18 male lambs (24.68 ± 2.89 kg mean body weight, about 8–9 months of age) were divided into three groups of six animals in each, following randomized block design. While animals in the control group (Gr I) were fed a standard TMR containing 195 g/kg crushed maize grain, 175.5 g/kg soybean meal, 260 g/kg wheat bran, 13 g/kg mineral mixture (without Se), 6.5 g/kg common salt and 350 g/kg wheat straw, animals in Gr II and Gr III were additionally supplemented with 0.15 mg Se/kg of diet through sodium selenite (inorganic Se) and Jevsel-101 (organic Se), respectively. Experimental feeding was done for a period of 90 days. To assess the humoral immune response, all the lambs were intramuscularly inoculated with a single dose (2 mL) of Haemorrhagic septicaemia oil adjuvant vaccine on day 0; and blood samples were collected on day 0, 30, 60 and 90. Supplementation of Se had no effect on serum total cholesterol, total protein, albumin, globulin, albumin:globulin ratio, T₃, T₄, T₄:T₃ ratio; serum Ca and P levels and SGOT and SGPT activity. However, there was a significant increase in the serum Se level, RBC GSH-Px activity and humoral immune response in both the Se supplemented groups as compared to control group. Average daily gain (g) was highest (110) in Gr III, followed by Gr II (98.2) and lowest in Gr I (89.1). Thus, supplementation of organic as well as inorganic Se was found to improve the growth rate, humoral immune response and antioxidant status of the lambs; and between two sources, organic Se was more effective than inorganic Se.     

The PKARI�� Subunit of Protein Kinase A Modulates the Activation of p90RSK1 and Its Function

Previously, we showed that interactions between p90^RSK1 (RSK1) and the subunits of type I protein kinase A (PKA) regulate the activity of PKA and cellular distribution of active RSK1 (Chaturvedi, D., Poppleton, H. M., Stringfield, T., Barbier, A., and Patel, T. B. (2006) Mol. Cell Biol. 26, 4586–4600). Here we examined the role of the PKARIα subunit of PKA in regulating RSK1 activation and cell survival. In mouse lung fibroblasts, silencing of the PKARIα increased the phosphorylation and activation of RSK1, but not of RSK2 and RSK3, in the absence of any stimulation. Silencing of PKARIα also decreased the nuclear accumulation of active RSK1 and increased its cytoplasmic content. The increased activation of RSK1 in the absence of any agonist and changes in its subcellular redistribution resulted in increased phosphorylation of its cytoplasmic substrate BAD and increased cell survival. The activity of PKA and phosphorylation of BAD (Ser-155) were also enhanced when PKARIα was silenced, and this, in part, contributed to increased cell survival in unstimulated cells. Furthermore, we show that RSK1, PKA subunits, D-AKAP1, and protein phosphatase 2A catalytic subunit (PP2Ac) exist in a complex, and dissociation of RSK1 from D-AKAP1 by either silencing of PKARIα, depletion of D-AKAP1, or by using a peptide that competes with PKARIα for binding to AKAPs, decreased the amount of PP2Ac in the RSK1 complex. We also demonstrate that PP2Ac is one of the phosphatases that dephosphorylates RSK, but not ERK1/2. Thus, in unstimulated cells, the increased phosphorylation and activation of RSK1 after silencing of PKARIα or depletion of D-AKAP1 are due to decreased association of PP2Ac in the RSK1 complex.Cyclic AMP-dependent protein kinase (PKA)³ plays a pivotal role in manifesting an array of biological actions ranging from cell proliferation and tumorigenesis to increased inotropic and chronotropic effects in the heart as well as regulation of long term potentiation and memory. The PKA holoenzyme is a heterotetramer and consists of two catalytic (PKAc) subunits bound to a dimer of regulatory subunits. To date, four isoforms of the PKAc (PKAcα, PKAcβ, PKAcγ, and PKAcδ) and four isoforms of the regulatory subunits (RIα, RIβ, RIIα, and RIIβ) have been described (1). The various isoforms of PKA subunits are expressed differently in a tissue- and cell-specific manner (2). In addition to binding and inhibiting the activity of PKAc via their pseudo substrate region (3–6), the R subunits also interact with PKA-anchoring proteins (AKAPs) and facilitate the localization of PKA in specific subcellular compartments (7, 8). More than 50 AKAP family members have been described, and although most of these have a higher affinity for the RII subunits (9), certain AKAPs such as D-AKAP1 and D-AKAP2 preferentially bind the PKARIα subunit (10–12). Because the AKAPs also bind other signaling molecules such as phosphatases (PP2B) and kinases (protein kinase C), they act as scaffolds to organize and integrate specific signaling events within specific compartments in the cells (7, 8, 13, 14).We have shown that the PKARIα and PKAcα subunits of PKA interact with the inactive and active forms of p90^RSK1 (RSK1), respectively (15). Binding of inactive RSK1 to PKARIα decreases the interactions between PKARIα and PKAc, whereas the association of active RSK1 with PKAc increases interactions between PKARIα and PKAc such that larger amounts of cAMP are required to activate PKAc in the presence of active RSK1 (15). Moreover, the indirect (via subunits of PKA) interaction of RSK1 with AKAPs is required for the nuclear localization of active RSK1 (15), and disruption of the interactions of RSK1·PKA complex from AKAPs results in increased cytoplasmic distribution of active RSK1 with a concomitant increase in phosphorylation of its cytosolic substrates such as BAD and reduced cellular apoptosis (15). These findings show the functional and biological significance of RSK1·PKA·AKAP interactions.Besides inhibiting PKAc activity, the physiological role of PKARIα is underscored by the findings that mutations in the PKAR1A gene that result in haploinsufficiency of PKARIα are the underlying cause of Carney complex (CNC) (16, 17). CNC is an autosomal dominant multiple neoplasia syndrome in which myxomas of the skin, heart, and/or vicera are recurrent and also associated with high incidence of endocrine and ovarian tumors as well as Schwannomas (18–20). The majority of patients with the multiple neoplasia CNC syndrome harbor mutations in the PKAR1A gene (21) that result in PKARIα haploinsufficiency. Importantly, however, loss of heterozygosity or alterations in PKA activity may not contribute toward the tumorigenicity in either CNC patients or mouse model of CNC (21). This suggests that loss of function(s) of PKARIα other than inhibition of PKA activity is(are) involved in the enhanced tumorigenicity in CNC patients and in the murine CNC model.Because RSK1 regulates cell growth, survival, and tumorigenesis (22–27), and because its subcellular localization and ability to inhibit apoptosis is regulated by its interactions via PKARIα with AKAPs (15), we reasoned that in conditions such as CNC where PKARIα levels are decreased, the increase in tumorigenicity may emanate from aberrant regulation of the activity and/or subcellular localization of RSK1. Therefore, herein we have investigated whether PKARIα regulates the activation of RSK1 and its biological functions. Decreasing expression of PKARIα by small interfering RNA (siRNA) enhanced the activation of RSK1, but not RSK2 or RSK3, in the absence of an agonist such as EGF. This was accompanied by an increase in the cytoplasmic localization of the active RSK1 and enhanced cell survival in the absence of any growth factor. Silencing of PKARIα also increased PKAc activity and while part of the anti-apoptotic response could be attributed to an increase in PKAc activity, activation of RSK1 under basal conditions contributed significantly to cell survival. The elevation in RSK1 activity upon PKARIα silencing was not due to increased PKAc activity. Rather the activation of RSK1 in the absence of PKARIα was due to a decrease in PP2A in the RSK1 complex. These findings demonstrate a novel role for PKARIα in the regulation of RSK1 activation, a key enzyme that mediates the downstream actions of the ERK1/2 cascade.     

Chronic Obstructive Pulmonary Disease and Altered Risk of Lung Cancer in a Population-Based Case-Control Study

Background

Chronic obstructive pulmonary disease (COPD) has been consistently associated with increased risk of lung cancer. However, previous studies have had limited ability to determine whether the association is due to smoking.

Methodology/Principal Findings

The Environment And Genetics in Lung cancer Etiology (EAGLE) population-based case-control study recruited 2100 cases and 2120 controls, of whom 1934 cases and 2108 controls reported about diagnosis of chronic bronchitis, emphysema, COPD (chronic bronchitis and/or emphysema), or asthma more than 1 year before enrollment. We estimated odds ratios (OR) and 95% confidence intervals (CI) using logistic regression. After adjustment for smoking, other previous lung diseases, and study design variables, lung cancer risk was elevated among individuals with a history of chronic bronchitis (OR = 2.0, 95% CI = 1.5–2.5), emphysema (OR = 1.9, 95% CI = 1.4–2.8), or COPD (OR = 2.5, 95% CI = 2.0–3.1). Among current smokers, association between chronic bronchitis and lung cancer was strongest among lighter smokers. Asthma was associated with a decreased risk of lung cancer in males (OR = 0.48, 95% CI = 0.30–0.78).

Conclusions/Significance

These results suggest that the associations of personal history of chronic bronchitis, emphysema, and COPD with increased risk of lung cancer are not entirely due to smoking. Inflammatory processes may both contribute to COPD and be important for lung carcinogenesis.     

Search of antitubercular activities in tetrahydroacridines: synthesis and biological evaluation

A series of 9-substituted tetrahydroacridines were synthesized by nucleophilic substitution of chloro group with different nucleophiles in 9-chlorotetrahydroacridine (2). The latter could be obtained by POCl(3) mediated cyclization of the intermediate enamine, which in turn, was prepared by acid catalyzed condensation of anthranilic acid and cyclohexanone. Most of the compounds on antitubercular evaluation against M. tuberculosis H37 Rv and H37 Ra strains exhibited potent activities with MIC 6.125-0.78 microg/mL comparable to the standard drugs.     

QSAR analysis of meclofenamic acid analogues as selective COX-2 inhibitors

The use of quantitative structure-activity relationships, since its advent, has become increasingly helpful in understanding many aspects of biochemical interactions in drug research. This approach was utilized to explain the relationship of structure with biological activity of selective COX-2 inhibitors. The enormity of the COX-2 discovery is reflected in the unprecedented speed at which research laboratories have sought to validate its clinical implications. Presented herein is a series of 21 derivatives of meclofenamic acid with selective COX-2 inhibitory activity. Several statistically significant regression expressions were obtained for both COX-1 and COX-2 inhibition using sequential multiple linear regression analysis method. Two of these models were selected and validated further, which revealed the importance of Kier molecular flexibility index for COX-2 inhibitory activity and the number of hydrogen bond donor atoms for COX-1 inhibitory activity. Additionally, linear correlation of molecular flexibility with COX-1 and COX-2 inhibitory activities revealed that flexibility of molecules at COX-2 active site can improve the selectivity of COX-2 inhibitors.     

Hepatitis C virus core protein inhibits tumor necrosis factor alpha-mediated apoptosis by a protective effect involving cellular FLICE inhibitory protein

We have previously shown that hepatitis C virus (HCV) core protein modulates multiple cellular processes, including those that inhibit tumor necrosis factor alpha (TNF-alpha)-mediated apoptosis. In this study, we have investigated the signaling mechanism for inhibition of TNF-alpha-mediated apoptosis in human hepatoma (HepG2) cells expressing core protein alone or in context with other HCV proteins. Activation of caspase-3 and the cleavage of DNA repair enzyme poly(ADP-ribose) polymerase were inhibited upon TNF-alpha exposure in HCV core protein-expressing HepG2 cells. In vivo protein-protein interaction studies displayed an association between TNF receptor 1 (TNFR1) and TNFR1-associated death domain protein (TRADD), suggesting that the core protein does not perturb this interaction. A coimmunoprecipitation assay also suggested that HCV core protein does not interfere with the TRADD-Fas-associated death domain protein (FADD)-procaspase-8 interaction. Further studies indicated that HCV core protein expression inhibits caspase-8 activation by sustaining the expression of cellular FLICE (FADD-like interleukin-1beta-converting enzyme)-like inhibitory protein (c-FLIP). Similar observations were also noted upon expression of core protein in context to other HCV proteins expressed from HCV full-length plasmid DNA or a replicon. A decrease in endogenous c-FLIP by specific small interfering RNA induced TNF-alpha-mediated apoptotic cell death and caspase-8 activation. Taken together, our results suggested that the TNF-alpha-induced apoptotic pathway is inhibited by a sustained c-FLIP expression associated with the expression of HCV core protein, which may play a role in HCV-mediated pathogenesis.