Acceleration of transformation of rat embryo cells by rat type C virus.

Sprague-Dawley and Fischer rat embryo cells became spontaneously transformed about 20 passages after release of endogenous ecotropic type C virus (SD-RaLV and F-RaLV). The virus-producing transformed cells showed loss of contact inhibition, increased growth rate, and tumorigenicity in vivo. Exogenous infection of other Fischer rat embryo cultures in early passage with SD-RaLV and F-RaLV markedly accelerated their rates of transformation.     

Mammalian tight junctions in the regulation of epithelial differentiation and proliferation

Tight junctions are important for the permeability properties of epithelial and endothelial barriers as they restrict diffusion along the paracellular space. Recent observations have revealed that tight junctions also function in the regulation of epithelial proliferation and differentiation. They harbour evolutionarily conserved protein complexes that regulate polarisation and junction assembly. Tight junctions also recruit signalling proteins that participate in the regulation of cell proliferation and differentiation. These signalling proteins include components that affect established signalling cascades and dual localisation proteins that can associate with junctions as well as travel to the nucleus where they regulate gene expression.     

Withanolides, a new class of natural cholinesterase inhibitors with calcium antagonistic properties

The withanolides 1-3 and 4-5 isolated from Ajuga bracteosa and Withania somnifera, respectively, inhibited acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) enzymes in a concentration-dependent fashion with IC50 values ranging between 20.5 and 49,2 microm and 29.0 and 85.2 microm for AChE and BChE, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that compounds 1, 3, and 5 are the linear mixed-type inhibitors of AChE, while 2 and 4 are non-competitive inhibitors of AChE with K(i) values ranging between 20.0 and 45.0 microm. All compounds were found to be non-competitive inhibitors of BChE with K(i) values ranging between 27.7 and 90.6 microm. Molecular docking study revealed that all the ligands are completely buried inside the aromatic gorge of AChE, while compounds 1, 3, and 5 extend up to the catalytic triad. A comparison of the docking results showed that all ligands generally adopt the same binding mode and lie parallel to the surface of the gorge. The superposition of the docked structures demonstrated that the non-flexible skeleton of the ligands always penetrates the aromatic gorge through the six-membered ring A, allowing their simultaneous interaction with more than one subsite of the active center. The affinity of ligands with AChE was found to be the cumulative effects of number of hydrophobic contacts and hydrogen bonding. Furthermore, all compounds also displayed dose-dependent (0.005-1.0 mg/mL) spasmolytic and Ca2+ antagonistic potentials in isolated rabbit jejunum preparations, compound 4 being the most active with an ED50 value of 0.09 +/- 0.001 mg/mL and 0.22 +/- 0.01 microg/mL on spontaneous and K+ -induced contractions, respectively. The cholinesterase inhibitory potential along with calcium antagonistic ability and safe profile in human neutrophil viability assay could make compounds 1-5 possible drug candidates for further study to treat Alzheimer's disease and associated problems.     

Kinetics of novel competitive inhibitors of urease enzymes by a focused library of oxadiazoles/thiadiazoles and triazoles

Based on structure of the substrate of urease and for the purpose of designing pharmacophore models for urease inhibitors, which could be effective in physiological and pharmacological studies, a series of twenty-five 1,3,4-diazole-2(3H)-thiones-2(3H)-thiones, 1,3,4-diazoles-2(3H)-thiones, and 1,2,4-tri-3-thiones (OSNs) were designed, synthesized, and evaluated for various kinetic parameters of urease inhibition. OSNs inhibited the activity of urease(s) in a concentration dependent fashion. Dixon as well as Lineweaver-Burk plots and their secondary replots indicated that the nature of inhibition was of pure competitive type for all the 25 compounds. 5-[4-(hydroxy)phenyl]-1,3,4-thiadiazole-2(3H)-thione was found to be the most active one with a Ki value of 2 microM. The Ki values were increased with an increase in substrate concentrations. Apparently, OSNs employ a homologous mechanism of action by exploiting a common transition catalysis state and acting as ligand chelators to form octahedral complexes with the urease enzymes in an orientation-specific mode. The inhibition was slightly potentiated by lower pH and not abolished in the presence of NH2OH (a scavenger of histidine residue). Because of their safe profile in the genotoxic assay, they may be pursued in the near future for human testing     

Tn10 transposase mutants with altered transpososome unfolding properties are defective in hairpin formation

Transposition reactions take place in the context of higher-order protein-DNA complexes called transpososomes. In the Tn10 transpososome, IHF binding to an "outside end" creates a bend in the DNA that allows the transposase protein to contact the end at two different sites, the terminal and subterminal binding sites. Presumably this helps to stabilize the transposase-end interaction. However, the DNA loop that is formed must be unfolded at a later stage in order for the transposon to integrate into other DNA molecules. It has been proposed that transpososome unfolding also plays a role in transposon excision. To investigate this possibility further, we have isolated and characterized transposase mutants with altered transpososome unfolding properties. Two such mutants were identified, R182A and R184A. Both mutants fail to carry out hairpin formation, an intermediate step in transposon excision, specifically with outside end-containing substrates. These results support the idea that transpososome unfolding and excision are linked. Also, based on the importance of residues R182 and R184 in transpososome unfolding, we propose a new model for the Tn10 transpososome, wherein both DNA ends of the transpososome make subterminal contacts with transposase.     

Bioactive phenolic compounds from a medicinal lichen, Usnea longissima

Natural products, longissiminone A (1) and longissiminone B (2), were isolated along with a known compound, glutinol (3), from a medicinal lichen, Usnea longissima. The structures of compounds 1 and 2 were determined with the help of spectroscopic studies. Compound 1 was found to possess potent anti-inflammatory activity in a cell-based contemporary assay. Cytotoxicity activity measured by cell viability assay showed 100% viability in the presence of 200 microg/mL conc. of these compounds.     

Differentially expressed genes: OCT-4, SOX2, STAT3, CDH1 and CDH2, in cultured mesenchymal stem cells challenged with serum of women with endometriosis

Endometriosis is a common chronic gynecological disorder defined as the presence of ectopic functional endometrial tissues, outside uterine cavity, primarily on the pelvic peritoneum and the ovaries. Several studies revealed a correlation between aberrant stem-cell activity in the endometrium and endometriosis. Yet the molecular and cellular behaviors of mesnchymal stem cells in development of endometriosis are hampered by lack of invitro experiments. Our aim was to explore morphological and molecular changes associated with mesenchymal stem cells (MSCs) exposition to serum derived from women with severe endometriosis. Two cell cultures of MSCs isolated from endometrial tissues of two endometriosis-free women. Each cell culture was treated individually with the serum of women with endometriosis (experimental group/n =?7), and serum of women without endometriosis (control group/ n = 4) for 14?days. Quantitative Real-Time PCR was performed later to reveal expression of OCT-4, CDH1 and CDH2, STAT3 and SOX2 genes. Morphologically, cells showed no significant changes. However from molecular point of view, we found increased expression in OCT-4, CDH1 and CDH2. For STAT3 and SOX2 we did not find a significant difference. This study shows that endometriosis serum induced molecular changes in human endometrial MSCs (EnMSCs) that might be related to altered cell behavior which may be a step in differentiation that may be completed invivo by other factors to complete the process of transition. Further researches are needed for optimization to reach differentiation.     

<Superscript>177</Superscript>Lu-DOTA-coupled minigastrin peptides: promising theranostic agents in neuroendocrine cancers

Treatment with radionuclide labeled regulatory peptides is a promising tool in the management of patients with inoperable receptor positive neuroendocrine tumors. Peptide receptor lutetium-177 radionuclide therapy currently has gained ample attention due to high specific accumulation of regulatory peptides at tumor cell surface and promising characteristics of β- and γ-energy photons of lutetium-177 radionuclide. In this study gastrin peptides analogues were labeled with lutetium-177 by subsequent mixing of ¹⁷⁷LuCl₃ (~?185 MBq), ammonium acetate buffer of 5 pH, gentistic acid, aqueous solution of gastrin peptide analogues (1 mg/mL) and heating the reaction mixture at 98 °C which resulted in high radiochemical yield (>?96%). Chromatographic analysis was carried out to analyze the radiochemical purity. The shelf life and serum stability results showed the labeled peptides are sufficiently stable up to 4-h. Glomerular filtration rate study results showed moderate filtration through kidneys. The GFR values of ¹⁷⁷Lu-MGCL2 and ¹⁷⁷Lu-MGCL4 was noted 48 mL/min and 45 mL/min, respectively. Biodistribution and scintigraphy study using rat and rabbit models showed minimal non-target accumulation, moderate uptake by liver and kidneys. The promising radiochemical yield, stability, GFR values and biodistribution results of ¹⁷⁷Lu-MGCL2 & 4 indicate, the agents can be tested clinically for PRRT procedures.