Effect of hyperphenylalaninemia induced during suckling on brain DNA metabolism in rat pups

We studied DNA metabolism (synthesis and degradation) in brain to investigate the effect of hyperphenylalaninemia induced in rats by treatment with PCPA or MPA plus PHE during suckling (4th–20th days of postnatal age) on cell proliferation and naturally occurring cell death. The incorporation of¹⁴C in DNA as percent of total radioactivity in the tissue, 30 min after administration of [¹⁴C]thymidine served as a measure of DNA synthesis in vivo, and the amount of radioactivity recovered in DNA as percent of total¹⁴C in the tissues of 21 day old rats, injected with [¹⁴C]thymidine on 2nd day after birth, indicated the turnover (degradation) of DNA. The results showed that the DNA content of cerebellum as well as cerebrum was reduced by treatment with PCPA plus PHE, while treatment with MPA plus PHE had no effect on DNA content in cerebellum but reduced the levels in cerebrum. Treatment with PCPA or MPA plus PHE reduced the synthesis of DNA in cerebrum of 11 day old rats but not in 21 day old rats, and the treatments did not affect DNA synthesis in cerebellum of either 11 or 21 day old rats. The turnover (degradation) of DNA was increased in both cerebellum and cerebrum from rats treated with PCPA plus PHE but MPA plus PHE treatment did not alter the DNA turnover either in cerebellu or in cerebrum. The activity of acid DNase was reduced in both cerebellum and cerebrum from 11 as well as 21 day old rats treated with PCPA plus PHE, but the enzyme activity was not altered in the tissues from rats of both ages treated with MPA plus PHE. The data thus indicate that in rats treated with PCPA plus PHE the reduction in cerebral DNA levels occurs due to reduced synthesis and/or increased turnover (degradation) of DNA but that the reduction in cerebellar DNA may occur only as a result of increased turnover (degradation), and that in rats treated with MPA plus PHE the reduction in cerebral DNA must occur due to reduced synthesis. This suggests that treatment of rats with PCPA plus PHE during suckling inhibits cell proliferation and/or increases naturally occurring cell death in both cerebellum and cerebrum while treatment with MPA plus PHE inhibits only cell proliferation and in cerebrum alone.     

Expression of ribosomal cistrons of human chromosomes at high resolution

The expression of ribosomal cistrons in the nucleolar organizer regions (NORs) has been studied with high resolution banding in the acrocentric chromosomes of 10 normal individuals. It was found that if a particular chromosome did not stain with silver nitrate at metaphase, then it did not stain at prophase either. Therefore, it is concluded that some of the acrocentric chromosomes have variable expression of NORs.     

Benzothiopyran-4-one based reversible inhibitors of the human cytomegalovirus (HCMV) protease

A novel class of CMV protease inhibitors based on a benzothiopyran-S,S-dioxide nucleus has been discovered. Enzyme kinetic data supports a reversible mode of inhibition for a representative member of this class, 2-(3-pyridyl-N-oxide)benzothiopyran-4-one-S,S-dioxide, 1. Experiments in the presence and absence of the disulfide reducing agent DTT suggest that the inhibition by 1 is not due to oxidative inactivation of the enzyme. Also presented are results of some SAR studies of the benzothiopyranone ring system.     

Wnt signaling induces epithelial differentiation during cutaneous wound healing

Background  

Cutaneous wound repair in adult mammals does not regenerate the original epithelial architecture and results in altered skin function. We propose that lack of regeneration may be due to the absence of appropriate molecular signals to promote regeneration. In this study, we investigated the regulation of Wnt signaling during cutaneous wound healing and the consequence of activating either the beta-catenin-dependent or beta-catenin-independent Wnt signaling on epidermal architecture during wound repair.     

In-silico identification of small molecules targeting H-Ras and in-vitro cytotoxicity with caspase-mediated apoptosis in carcinoma cells

H-Ras oncogene plays a critical role in the transformation of normal cells to a malignant phenotype through constitutive activation of the GTP bound protein leading to uncontrolled cell proliferation in several human cancers. Thus, H-Ras oncoprotein serves as an excellent target for anticancer drug discovery. To identify novel H-Ras inhibitors, we performed structure-based virtual screening of the Maybridge HitFinder™ library using Schrodinger suite. Thirty ligands from the chemical library were identified as they showed preferential in silico binding initially to H-Ras proteins with Gly12Val, Gly13Asp, and Gly12Val-Gly13Asp mutations. Absorption, distribution, metabolism, excretion, and toxicity profile confirmed drug-like properties of the compounds. Three representative molecules were tested for antiproliferative effect on T24 urinary bladder carcinoma cell line, MCF-7 breast cancer cell line and HDF-7 normal dermal fibroblast cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Two compounds (Cmpds) showed antiproliferative activity exclusively in the cancer cell lines with minimal effect on the control HDF-7 cells. The effect of compound treatment on cell cycle progression, assessed by propidium iodide (PI) staining, depicted increased arrest of T24 cell line in the sub G1 phase. Further, Annexin-V PI dual staining and pan caspase inhibitor Z-VAD-fmk indicated caspase-dependent apoptotic activity of Cmpds 1 and 3. Our findings demonstrate caspase-dependent apoptotic activity of Cmpds 1 and 3 selectively against Gly12Val mutated T24 cancer cell line implicating a potential for treatment of bladder cancer. We envisage that these molecules may be promising candidates with potential therapeutic value in H-Ras mutation-associated cancers.