Antihyperlipidemic effect of bis-1,7-(2-hydroxyphenyl)-hepta-1,6-diene-3,5-dione, a curcumin analog, on nicotine and streptozotocin treated rats

Diabetes and smoking have been considered as major health problems individually and their seriousness related to health hazard has been well reported. Data regarding the possible contribution of cigarette smoking to the development of diabetes are scarce and inconclusive. The aim was to investigate the effect of nicotine on diabetes and to analyze the effect of bis demethoxy curcumin analog (BDMCA) in streptozotocin (STZ) and nicotine-induced toxicity. The tissue lipids were extracted according to the method of Folch et al. Plasma and tissue cholesterol was estimated by the method of Allain et al. using reagent kit. Triglycerides were estimated by the method of Foster and Dunn. Free fatty acids were estimated by the method of Falholt et al. Tissue phospholipids were estimated by the method of Zilversmit and Davis. From our study, we found that nicotine not only aggravates diabetic complications but also increased the risk for diabetes. BDMCA, at a dose 80 mg/kg body weight was found to be effective in decreasing toxic effects induced by nicotine and STZ. Our data provide new evidence that cigarette smoking is an additional important factor that could be targeted for the prevention of diabetic complications.     

Purification of a recombinant histidine-tagged lactate dehydrogenase from the malaria parasite,Plasmodium vivax,and characterization of its properties

Lactate dehydrogenase (LDH) of the malaria parasite, Plasmodium vivax (Pv), serves as a drug target and immunodiagnostic marker. The LDH cDNA generated from total RNA of a clinical isolate of the parasite was cloned into pRSETA plasmid. Recombinant his-tagged PvLDH was over-expressed in E. coli Rosetta2DE3pLysS and purified using Ni²⁺-NTA resin giving a yield of 25–30 mg/litre bacterial culture. The recombinant protein was enzymatically active and its catalytic efficiency for pyruvate was 5.4 × 10⁸ min^?1 M^?1, 14.5 fold higher than a low yield preparation reported earlier to obtain PvLDH crystal structure. The enzyme activity was inhibited by gossypol and sodium oxamate. The recombinant PvLDH was reactive in lateral flow immunochromatographic assays detecting pan- and vivax-specific LDH. The soluble recombinant PvLDH purified using heterologous expression system can facilitate the generation of vivax LDH-specific monoclonals and the screening of chemical compound libraries for PvLDH inhibitors.     

Combination of Omega-3 Fatty Acids,Lithium, and Aripiprazole Reduces Oxidative Stress in Brain of Mice with Mania

Manic episode in bipolar disorder (BD) was evaluated in the present study with supplementation of omega-3 fatty acids in combination with aripiprazole and lithium on methylphenidate (MPD)-induced manic mice model. Administration of MPD 5 mg/kg bw intraperitoneally (i.p.) caused increase in oxidative stress in mice brain. To retract this effect, supplementation of omega-3 fatty acids 1.5 ml/kg (p.o.), aripiprazole 1.5 mg/kg bw (i.p.), and lithium 50 mg/kg bw (p.o) were given to mice. Omega-3 fatty acids alone and in combination with aripiprazole- and lithium-treated groups significantly reduced the levels of superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation products (thiobarbituric acid reactive substances) in the brain. MPD treatment significantly decreased the reduced glutathione (GSH) level and glutathione peroxidase (GPx) activity, and they were restored by supplementation of omega-3 fatty acids with aripiprazole and lithium. There is no remarkable difference in the effect of creatine kinase (CK) activity between MPD-induced manic model and the treatment groups. Therefore, our results demonstrate that oxidative stress imbalance and mild insignificant CK alterations induced by administration of MPD can be restored back to normal physiological levels through omega-3 fatty acids combined with lithium and aripiprazole that attributes to effective prevention against mania in adult male Swiss albino mice.     

The tumour suppressor C/EBPδ inhibits FBXW7 expression and promotes mammary tumour metastasis

Inflammation and hypoxia are known to promote the metastatic progression of tumours. The CCAAT/enhancer-binding protein-δ (C/EBPδ, CEBPD) is an inflammatory response gene and candidate tumour suppressor, but its physiological role in tumourigenesis in vivo is unknown. Here, we demonstrate a tumour suppressor function of C/EBPδ using transgenic mice overexpressing the Neu/Her2/ERBB2 proto-oncogene in the mammary gland. Unexpectedly, this study also revealed that C/EBPδ is necessary for efficient tumour metastasis. We show that C/EBPδ is induced by hypoxia in tumours in vivo and in breast tumour cells in vitro, and that C/EBPδ-deficient cells exhibit reduced glycolytic metabolism and cell viability under hypoxia. C/EBPδ supports CXCR4 expression. On the other hand, C/EBPδ directly inhibits expression of the tumour suppressor F-box and WD repeat-domain containing 7 gene (FBXW7, FBW7, AGO, Cdc4), encoding an F-box protein that promotes degradation of the mammalian target of rapamycin (mTOR). Consequently, C/EBPδ enhances mTOR/AKT/S6K1 signalling and augments translation and activity of hypoxia-inducible factor-1α (HIF-1α), which is necessary for hypoxia adaptation. This work provides new insight into the mechanisms by which metastasis-promoting signals are induced specifically under hypoxia.     

Knockout of the folate transporter <Emphasis Type="Italic">folt-1</Emphasis> causes germline and somatic defects in <Emphasis Type="Italic">C. elegans</Emphasis>

Background  

The C. elegans gene folt-1 is an ortholog of the human reduced folate carrier gene. The FOLT-1 protein has been shown to transport folate and to be involved in uptake of exogenous folate by worms. A knockout mutation of the gene, folt-1(ok1460), was shown to cause sterility, and here we investigate the source of the sterility and the effect of the folt-1 knockout on somatic function.     

Role of reduced folate carrier in intestinal folate uptake

Studies from our laboratory and others have characterized different aspects of the intestinal folate uptake process and have shown that the reduced folate carrier (RFC) is expressed in the gut and plays a role in the uptake process. Little, however, is known about the actual contribution of the RFC system toward total folate uptake by the enterocytes. Addressing this issue in RFC knockout mice is not possible due to the embryonic lethality of the model. In this study, we describe the use of the new approach of lentivirus-mediated short hairpin RNA (shRNA) to selectively silence the endogenous RFC of the rat-derived intestinal epithelial cells (IEC-6), an established in vitro model for folate uptake, and examined the effect of such silencing on folate uptake. First we confirmed that the initial rate of [(3)H]folic acid uptake by IEC-6 cells was pH dependent with a markedly higher uptake at acidic compared with alkaline pH. We also showed that the addition of unlabeled folic acid to the incubation buffer leads to a severe inhibition ( approximately 95%) in [(3)H]folic acid (16 nM) uptake at buffer pH 5.5 but not at buffer pH 7.4. We then examined the effect of treating (for 72 h) IEC-6 cells with RFC-specific shRNA on the levels of RFC protein and mRNA and observed substantial reduction in the levels of both parameters ( approximately 80 and 78%, respectively). Such a treatment was also found to lead to a severe inhibition ( approximately 90%) in initial rate of folate uptake at buffer pH 5.5 (but not at pH 7.4); uptake of the unrelated vitamin, biotin, on the other hand, was not affected by such a treatment. These results demonstrate that the RFC system is the major (if not the only) folate uptake system that is functional in intestinal epithelial cells.     

SMS: sequence, motif and structure--a database on the structural rigidity of peptide fragments in non-redundant proteins

Structure prediction methods aim to identify the relationship between the amino acid sequence of an unknown protein and information comprised in databases of known protein structures. Towards this end, we created a database by combining the amino acid sequences and the corresponding three-dimensional atomic coordinates for all the 25% non-redundant protein chains available in the Protein Data Bank. It contains information about the peptide fragments that are 5 to 10 residues long. In addition, options are provided for the users to visualize the individual motifs and the superposed fragments in the client machine. Further, useful functionalities areprovided to look for similar sequence motifs in all the sequence databases like PDB, 90% non-redundant protein chains, Genome database, PIR and Swiss-Prot. The database is being updated at regular intervals and the same can be accessed over the World Wide Web interface at the following URL: http://pranag.physics.iisc.ernet.in/sms/.     

A facile 1,3-dipolar cycloaddition of azomethine ylides to 2-arylidene-1,3-indanediones: synthesis of dispiro-oxindolylpyrrolothiazoles and their antimycobacterial evaluation

A facile 1,3-dipolar cycloaddition of azomethine ylide generated in situ from the reaction of 1,3-thiazolane-4-carboxylic acid and isatin to 2-arylidene-1,3-indanediones furnished novel dispiro-oxindolylpyrrolothiazoles regio- and stereo-selectively in moderate to good yields (60-92%). In vitro antitubercular screening of 27 compounds against Mycobacterium tuberculosis H37Rv (MTB) disclosed that spiro[5.3']-5'-nitrooxindolespiro-[6.3″]-1H-inden-1″,3″(2H)-dione-7-(4-bromophenyl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazole has the maximum potency with a minimum inhibitory concentration (MIC) of 1.4 μM against MTB, being 3.4 and 5.4 times more potent than ciprofloxacin and ethambutol, respectively.     

Length‐dependent stability of α‐helical peptide upon adsorption to single‐walled carbon nanotube

Earlier studies have shown that the helical content of α‐helical peptide decreases upon its interaction with carbon nanotube (CNT). Further, the length of the α‐helix varies from few residues in the small globular protein to several number of residues in structural and membrane proteins. In structural and membrane proteins, helices are widely present as the supercoil i.e., helical bundles. Thus, in this study, the length‐dependent interaction pattern of α‐helical peptides with CNT and the stability of isolated α‐helical fragment versus supercoiled helical bundle upon interaction with CNT have been investigated using classical molecular dynamics (MD) simulation. Results reveal that the disruption in the helical motif on interaction with CNT is directly proportional to the length of the helix. Also it is found that the shorter helix does not undergo noticeable changes in the helicity upon adsorption with CNT. On the other hand, helicity of longer peptides is considerably affected by its interaction with CNT. In contrast to the known fact that the stability of the helix increases with its length, the disruption in the helical peptide increases with its length upon its interaction with CNT. Comparison of results shows that structural changes in the isolated helical fragment are higher than that in supercoiled helix. In fact, helical chain in supercoiled bundle does not undergo significant changes in the helicity upon interaction with CNT. Both the length of the helical peptide and the inherent stability of the helical unit in the supercoiled helix influence the interaction pattern with the CNT. © 2012 Wiley Periodicals, Inc. Biopolymers 99: 357–369, 2013.