1,4-Diaryl-substituted triazoles as cyclooxygenase-2 inhibitors: Synthesis,biological evaluation and molecular modeling studies

A novel group of 1,4-diaryl-substituted triazoles was designed and synthesized by introducing the cyclooxygenase-2 (COX-2) pharmacophore SO₂NH₂ attached to one aryl ring and various substituents (H, F, Cl, CH₃ or OCH₃) attached to the other aryl ring. The effects of size and flexibility of the compounds upon COX-1/COX-2 inhibitory potency and selectivity was studied by increasing the size of an alkyl linker chain [(–CH₂)_n, where n = 0, 1, 2]. In vitro COX-1/COX-2 inhibition studies showed that all compounds (14–18, 21–25 and 28–32) are more potent inhibitors of COX-2 isozyme (IC₅₀ = 0.17–28.0 μM range) compared to COX-1 isozyme (IC₅₀ = 21.0 to >100 μM range). Within the group of 1,4 diaryl-substituted triazoles, 4-{2-[4-(4-chloro-phenyl)-[1,2,3]triazol-1-yl]-ethyl}-benzenesulfonamide (compound 30) displayed highest COX-2 inhibitory potency and selectivity (COX-1: IC₅₀ = >100 μM, COX-2: IC₅₀ = 0.17 μM, SI >588). Molecular docking studies using the catalytic site of COX-1 and COX-2, respectively, provided complementary theoretical support for the obtained experimental biological structure–activity relationship data. Results of molecular docking studies revealed that COX-2 pharmacophore SO₂NH₂ in compound 30 is positioned in the secondary pocket of COX-2 active site; with the nitrogen atom of the SO₂NH₂ group being hydrogen bonded to Q192 (N?OC = 2.85 Å), and one of the oxygen atoms of SO₂NH₂ group forming a hydrogen bond to H90 (SO?N = 2.38 Å).     

Plant proteomics in India and Nepal: current status and challenges ahead

Plant proteomics has made tremendous contributions in understanding the complex processes of plant biology. Here, its current status in India and Nepal is discussed. Gel-based proteomics is predominantly utilized on crops and non-crops to analyze majorly abiotic (49 %) and biotic (18 %) stress, development (11 %) and post-translational modifications (7 %). Rice is the most explored system (36 %) with major focus on abiotic mainly dehydration (36 %) stress. In spite of expensive proteomics setup and scarcity of trained workforce, output in form of publications is encouraging. To boost plant proteomics in India and Nepal, researchers have discussed ground level issues among themselves and with the International Plant Proteomics Organization (INPPO) to act in priority on concerns like food security. Active collaboration may help in translating this knowledge to fruitful applications.     

Bacteriophage immobilized graphene electrodes for impedimetric sensing of bacteria (Staphylococcus arlettae)

Bacteriophages are a class of viruses that specifically infect and replicate within a bacterium. They possess inherent affinity and specificity to the particular bacterial cells. This property of bacteriophages makes them an attractive biorecognition element in the field of biosensor development. In this work, we report the use of an immobilized bacteriophage for the development of a highly sensitive electrochemical sensor for Staphylococcus arlettae, bacteria from the pathogenic family of coagulase-negative staphylococci (CNS). The specific bacteriophages were covalently immobilized on the screen-printed graphene electrodes. Thus, the fabricated bacteriophage biosensor displayed quantitative response for the target bacteria (S. arlettae) for a broad detection range (2.0–2.0 × 10⁶ cfu). A fast response time (2 min), low limit of detection (2 cfu), specificity, and stability over a prolonged period (3 months) are some of the important highlights of the proposed sensor. The practical utility of the developed sensor has been demonstrated by the analysis of S. arlettae in spiked water and apple juice samples.     

Residue-level prediction of DNA-binding sites and its application on DNA-binding protein predictions

Protein-DNA interactions are crucial to many cellular activities such as expression-control and DNA-repair. These interactions between amino acids and nucleotides are highly specific and any aberrance at the binding site can render the interaction completely incompetent. In this study, we have three aims focusing on DNA-binding residues on the protein surface: to develop an automated approach for fast and reliable recognition of DNA-binding sites; to improve the prediction by distance-dependent refinement; use these predictions to identify DNA-binding proteins. We use a support vector machines (SVM)-based approach to harness the features of the DNA-binding residues to distinguish them from non-binding residues. Features used for distinction include the residue's identity, charge, solvent accessibility, average potential, the secondary structure it is embedded in, neighboring residues, and location in a cationic patch. These features collected from 50 proteins are used to train SVM. Testing is then performed on another set of 37 proteins, much larger than any testing set used in previous studies. The testing set has no more than 20% sequence identity not only among its pairs, but also with the proteins in the training set, thus removing any undesired redundancy due to homology. This set also has proteins with an unseen DNA-binding structural class not present in the training set. With the above features, an accuracy of 66% with balanced sensitivity and specificity is achieved without relying on homology or evolutionary information. We then develop a post-processing scheme to improve the prediction using the relative location of the predicted residues. Balanced success is then achieved with average sensitivity, specificity and accuracy pegged at 71.3%, 69.3% and 70.5%, respectively. Average net prediction is also around 70%. Finally, we show that the number of predicted DNA-binding residues can be used to differentiate DNA-binding proteins from non-DNA-binding proteins with an accuracy of 78%. Results presented here demonstrate that machine-learning can be applied to automated identification of DNA-binding residues and that the success rate can be ameliorated as more features are added. Such functional site prediction protocols can be useful in guiding consequent works such as site-directed mutagenesis and macromolecular docking.     

Differential response of antioxidant enzymes in leaves of necrotic wheat hybrids and their parents

The leaves of necrotic hybrid of wheat ( Triticum aestivum L.) exhibited high superoxide content associated with increased lipid peroxidation and membrane damage in earlier studies (Khanna-Chopra et al. 1998, Biochem Biophys Res Commun 248: 712–715; Dalal and Khanna-Chopra 1999, Biochem Biophys Res Commun 262: 109–112). In the present study, we investigated the activities of the antioxidant enzymes in the leaves of necrotic wheat hybrids, Kalyansona×C306 (K×C) and WL711×C306 (WL×C) and their parents at different developmental stages. The K×C hybrid exhibited more severe necrosis than WL×C. In K×C, superoxide dismutase (SOD) activity showed no increase over the parents, while WL×C showed an early increase, but it was possibly insufficient to scavenge increased superoxide. Activities of guaiacol peroxidase, ascorbate peroxidase and glutathione reductase were enhanced, while catalase exhibited a decrease in activity, with the appearance of visible necrosis in both the hybrids. The isozyme profile of the antioxidant enzymes was similar in the hybrids and their parents. One existing isoform of guaiacol peroxidase showed an early appearance in the hybrid and increased in intensity with the progression of necrosis. The results reveal a differential response of antioxidant enzymes in necrotic wheat hybrids as compared to their parents. The response differed in magnitude at developmental stages of the leaves, which might be related to the intensity of necrosis expressed by the hybrids.     

Primary subcutaneous Nocardia asteroides infection in a renal allograft recipient

Nocardia asteroides is an important opportunistic pathogen in immunocompromised hosts. The primary infection is usually in the lungs and is followed by dissemination to other parts of the body. Primary subcutaneous infection with Nocardia asteroides has been reported rarely (three reports) and no such case has been reported in a renal transplant recipient. We describe here a case of renal transplant recipient who developed primary subcutaneous infection with Nocardia asteroides within one and half years of the transplantation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Potential Role of Cerebral Glutathione in the Maintenance of Blood-Brain Barrier Integrity in Rat

Using the model of glutathione (GSH) depletion, possible role of GSH in the maintenance of blood-brain barrier (BBB) integrity was evaluated in rats. Administration (ip) of GSH depletors, diethyl maleate (DEM, 1–4 mmol/kg), phorone (2–3 mmol/kg) and 2-cyclohexene-1-one (CHX, 1 mmol/kg), to male adults was found to deplete brain and liver GSH and increase the BBB permeability to micromolecular tracers (sodium fluorescein and [¹⁴C]sucrose) in a dose-dependent manner at 2h. However, BBB permeability to macromolecular tracers such as horseradish peroxidase and Evan's blue remained unaltered. It was also shown that observed BBB permeability dysfunction was associated with brain GSH depletion. A lower magnitude of BBB increase in rat neonates, as compared to adults, indicated a possible bigger role of GSH in the BBB function of mature brain. The treatment with N-acetylcysteine, methionine and GSH provided a partial to full protection against DEM-induced brain (microvessel) GSH depletion and BBB dysfunction; however, the treatment with -tocopherol, ascorbic acid and turmeric were not effective. Our studies showed that cerebral GSH plays an important role in maintaining the functional BBB integrity.     

The effect of duration and time of food availability on the photoperiodic response in the male house sparrow, Passer domesticus

We investigated the effects of food availability on the seasonal testicular growth in the photoperiodic house sparrow (Passer domesticus). Two experiments were performed, each lasting 4 weeks. In experiment 1, sparrows were exposed to natural (NDL; group 1), short (8L:16D; group 2) and long (16L:8D; groups 3-5) day lengths with access to food ad libitum (groups 1-3) or for 10 h (zeitgeber time (zt) 0-10, group 4; zt 0 is the time of light onset) or for 8 h (zt 8-16, group 5). Testes recrudesced under long, but not short and natural, day lengths, and the recrudescence under long days was influenced by the duration of food availability. In experiment 2, the sparrows were exposed to short (8L:16D, group 1) and long (16L:8D, groups 2-5) day lengths with access to food ad libitum (for groups 1 and 2) or for 6 h (for groups 3-5) at different times during the 16 h light period (group 3- zt 0-6, group 4- zt 5-11, group 5- zt 10-16). As the expected, the testes recrudesced only under long lengths, but the photoinduction was variable among the 4 groups. The testes grew to full size in groups 2 and 3 that received food either ad libitum or for 6 h at zt 0-6, but to sub-maximal size in the groups that received 6 h food either at zt 5-11 (group 4) or at zt 10-16 (group 5). Altogether, these results support the idea that the photoperiodic regulation of reproduction in a seasonally breeding species is influenced both by the duration and the time of food availability.