Generation of Hydroxyl Radicals by Nucleohistone-Bound Metal-Adriamycin Complexes

A recently developed method has been utilized to demonstrate the generation of hydroxyl radicals (HO^bullet) in the immediate proximity of DNA by cop-per(II)/iron(HI)-adriamycin in the presence of ascorbate and hydrogen peroxide. SECCA, a succinylated derivative of coumarin, generates the fluorescent 7-hydroxy-SECCA following reaction with HO^bullet. SECCA was coupled to polylysine or to histone HI and then complexed to DNA. When HO' was generated in the proximity of DNA by polylysine-coupled iodine-125, which emits short range Auger electrons, 7-hydroxy-SECCA was produced. DMSO was only moderately efficient in reducing the fluorescence induction, demonstrating the “local” generation of HO^bullet in this system. Copper(II)/iron(III)-adriamycin in the presence of ascorbate and hydrogen peroxide generated the fluorescent 7-hydroxy-SECCA both when SECCA was free in solution and when SECCA was DNA-conjugated. With SECCA free in solution, the fluorescence induction was almost eliminated in the presence of HO^bullet scavengers (ethanol, tertbutanol or DMSO) and the relative efficiency of the scavengers in reducing the fluorescence followed their rate constant with HO^bullet. Furthermore, SECCA incubated with a singlet oxygen-generating compound demonstrated no fluorescence induction. When SECCA was positioned in close proximity to DNA as a SECCA-histone-H1-DNA complex, the relative efficiency of the scavengers in reducing the fluorescence still followed their rate constant with HO'; overall however the scavengers were much less effective in reducing the fluorescence, due presumably to the formation of HO^bullet radical in the immediate vicinity of DNA. These data suggest that copper(II)/iron(III)-adriamycin produces HO' in the presence of ascorbate and hydrogen peroxide whether unbound or bound to DNA and suggest that in the latter case scavengers would not prevent HO^bullet from attacking chromatin. In addition, the ability of DMSO to trap HO^bullet was shown to decrease as the conformation of the HI-DNA complex becomes more compact indicating the strong dependence of the trapping ability on chromatin conformation.     

Transactivation of human immunodeficiency virus type 1 long terminal repeats by cell surface tumor necrosis factor alpha.

Tumor necrosis factor alpha (TNF-alpha) is expressed in secreted and cell surface (csTNF-alpha) forms by activated monocytic and T cells. In this report, we demonstrate that csTNF-alpha may predominantly regulate the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) activation in the promonocytic cell line U937 and in the Epstein-Barr virus-transformed B-cell line BH1. Anti-TNF-alpha antibody suppressed both the constitutive expression of the HIV-1 LTR in BH1 cells and the expression induced by phorbol 12-myristate 13-acetate in U937 cells. This suppression was found to be mediated via csTNF-alpha. No correlation between the HIV-1 LTR activation and the secretion of TNF-alpha was evident in these cell lines. Suppression of TNF-alpha secretion by cyclosporin A or by a serine protease inhibitor did not suppress the HIV-1 LTR activation. These observations suggest a novel biological role for csTNF-alpha in the immunopathogenesis of AIDS.     

Molecular dynamics simulations on interaction between bacterial proteins: Implication on pathogenic activities

We perform molecular dynamics simulation studies on interaction between bacterial proteins: an outer‐membrane protein STY3179 and a yfdX protein STY3178 of Salmonella Typhi. STY3179 has been found to be involved in bacterial adhesion and invasion. STY3178 is recently biophysically characterized. It is a soluble protein having antibiotic binding and chaperon activity capabilities. These two proteins co‐occur and are from neighboring gene in Salmonella Typhi‐occurrence of homologs of both STY3178 and STY3179 are identified in many Gram‐negative bacteria. We show using homology modeling, docking followed by molecular dynamics simulation that they can form a stable complex. STY3178 belongs to aqueous phase, while the beta barrel portion of STY3179 remains buried in DPPC bilayer with extra‐cellular loops exposed to water. To understand the molecular basis of interaction between STY3178 and STY3179, we compute the conformational thermodynamics which indicate that these two proteins interact through polar and acidic residues belonging to their interfacial region. Conformational thermodynamics results further reveal instability of certain residues in extra‐cellular loops of STY3179 upon complexation with STY3178 which is an indication for binding with host cell protein laminin.     

Utilization of cellobiose and production of β-clucosidase by nine yeast species

A comparative study of 9 yeasts namely, Candida blankii,C.humicola,C.ishiwadae,C.rhagii,C.tropicalis,Hensenula subpelliculosa,Saccharomyces cerevisiae,Trichosporon cutaneum and Tr.pullulans was carried out for the production of extracellular and cell bound β-glucosidase using cellobiose as the substrate. Trichosporon cutaneum was found to be the best extracellular as well as cell bound β-clucosidase producer and the former activity was more than the latter. In the rest of the yeasts most of them showed more cell bound β-glucosidase as compared to the extracellular.     

Establishment of epithelial cell lines from adult mouse regenerating liver

A simple technique for developing epithelial cell lines from regenerating mouse liver has been described. Twenty-one epithelial cell lines have been developed and can be divided into four groups according to their morphology. All these near diploid cell lines have the capacity to metabolize diverse classes of chemical carcinogens (3-methylcholanthrene, 2-acetylaminofluorene, dimethylnitrosamine and aflatoxin B1) to cytotoxic metabolites. It is not yet possible to determine which ones of these cell lines originated from hepatocytes. Studies are in progress to further characterize and to use these cell lines as lethally irradiated feeder layers for cell-mediated activation of various classes of chemical carcinogens and mutagens with C3H/10T1/2 mouse embryo fibroblasts as indicator cells.     

Anisotropic analysis of bone — Some two-dimensional problems

The solutions of the two-dimensional problems of concentrated forces, double forces and stresses due to a pressurized cavity in bone have been reported, treating bone as an anisotropic material. Using analytic functions of several complex variables, and starting from Lekhnitskii's solution for a concentrated force in an infinite plane, expressions for stresses for various cases have been obtained. Numerical results of stress distributions for various material axis orientations have been presented and compared with isotropy. The stress distributions for double forces in a semi-infinite plane, for various degrees of anisotropy, have also been included.     

Abscisic acid as an inhibitor of RNA synthesis by RNA polymerase in vitro

Abscisic acid interacts with DNA which increases the stabilityof the double strand against heat or alkaline denaturation.Abscisic acid added to RNA polymerase systems isolated fromthe chromatin of coconut nuclei inhibits RNA synthesis by loweringthe template activity of DNA. No interaction with RNA polymeraseor the initiation factor (factor B) is discernible. (Received May 18, 1972; )     

Incidence of Appendicitis over Time: A Comparative Analysis of an Administrative Healthcare Database and a Pathology-Proven Appendicitis Registry

ImportanceAt the turn of the 21^st century, studies evaluating the change in incidence of appendicitis over time have reported inconsistent findings.ObjectivesWe compared the differences in the incidence of appendicitis derived from a pathology registry versus an administrative database in order to validate coding in administrative databases and establish temporal trends in the incidence of appendicitis.DesignWe conducted a population-based comparative cohort study to identify all individuals with appendicitis from 2000 to2008.ResultsThe administrative database (PPV = 83.0%) overestimated the incidence of appendicitis (100.3 per 100,000) when compared to the pathology registry (84.2 per 100,000). Codes for perforated appendicitis were not reliable (PPV = 52.4%) leading to overestimation in the incidence of perforated appendicitis in the administrative database (34.8 per 100,000) as compared to the pathology registry (19.4 per 100,000). The incidence of appendicitis significantly increased over time in both the administrative database (APC = 2.1%; 95% CI: 1.3, 2.8) and pathology registry (APC = 4.1; 95% CI: 3.1, 5.0).

Conclusion & Relevance

The administrative database overestimated the incidence of appendicitis, particularly among perforated appendicitis. Therefore, studies utilizing administrative data to analyze perforated appendicitis should be interpreted cautiously.