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R Mermelstein

Publications and source records attributed to R Mermelstein.

44 records · Page 3Linked to original sources
PubMed1981

Nitrated fluorene derivatives are potent frameshift mutagens.

Nitrated derivatives if fluorene are potent frameshift-type mutagens. A reduction of the nitro function is required for the expression of mutagenicity. Hydroxylamines are the presumed key intermediates, which following esterification to electrophiles are capable of forming adducts with cellular DNA. Evidence in support of this mechanism is obtained by the use of tester strains having a functional uvrB gene product or lacking specific nitroreductases. The mutagenic potency of nitrated fluorenes increases upon successive addition of nitro groups reaching a peak at the trisubstituted state. Addition of a 4th nitro group leads to decreased activity.

Fluorenes↗
PubMed1981

4-Nitroquinoline-1-oxide: factors determining its mutagenicity in bacteria.

In bacteria, 4-nitroquinoline-1-oxide (NQO) causes primarily mutations of the base-substitution type although frameshift mutations are also induced. The adducts formed are presumably recognized by error-prone DNA repair enzymes as evidenced by the much greater activity in plasmid pKM101-bearing tester strains. Although reduction of the nitro group appears to be required for mutagenic activity, this reduction is not catalyzed by the nitroreductase required for the demonstration of the mutagenicity in bacteria of other nitro-containing mutagens (nitrofurans, 2-nitronaphthalene, nitrofluorenes). The reduction of the nitro group appears to be catalyzed by a different nitroreductase. The mutagenicity of the non-carcinogenic 3-methyl-4-nitroquinoline-1-oxide (meNQO) may be related to this newly recognized nitroreductase. It is proposed, further, that the ultimate mutagenic intermediates derived from NQO and MeNQO differ.

4-Nitroquinoline-1-oxide↗
PubMed1981

The extraordinary mutagenicity of nitropyrenes in bacteria.

Nitropyrenes cause frameshift mutations in Salmonella typhimurium. This activity which is restricted to frameshift mutations is unusual in several respects: (a) Nitropyrenes, as a class, are the most mutagenic chemicals reported in the literature; (b) The mutagenicity depends upon the formation of adducts between DNA and nitropyrene metabolites; (c) The penultimate intermediates responsible for mutagenic activity (hydroxylamines) are not obtained in all instances by reduction of the nitro function by the "classical" nitroreductase (the one that acts on nitrofurans and other simple nitrated polycyclic aromatic hydrocarbons) but by another nitroreductase which appears to be specific for higher nitrated polycyclic aromatic hydrocarbons; (d) The mutagenicity of nitropyrenes is enhanced when resting rather than growing bacterial cultures are used.

Escherichia coli↗
PubMed1980

Nitropyrenes: isolation, identificaton, and reduction of mutagenic impurities in carbon black and toners.

Extracts of selected xerographic toners and copies were found to be mutagenic in the Salmonella assay. The activity was independent of the xerographic hardware and process and was traced to nitropyrenes present as impurities in the carbon black, the toner colorant. Manufacturing process changes resulted in a substantial reduction of the nitropyrene content of the carbon black and thus in the mutagenicity of the corresponding toners. Nitropyrenes are potent frameshift mutagens, and possible mechanisms for their biological action are discussed.

Biotransformation↗
PubMedDate not supplied

Self-concept changes over time in cognitive-behavioral treatment for smoking cessation.

A smoker self-concept and an abstainer self-concept are individual difference variables that have been shown to predict smoking cessation. We examined whether these self-concept constructs changed as a function of participating in a clinic-based smoking cessation program and, specifically, whether these changes occurred differentially between posttreatment smokers and abstainers. Subjects completed the Smoker Self-concept scale and the Abstainer Self-concept scale at three time points: pretreatment, posttreatment, and 3 months' posttreatment. Smoking status was assessed and biochemically verified directly after quit day and 3 months' posttreatment. Results indicated that abstainers' smoker self-concept decreased more precipitously over time compared to smokers'. Abstainers showed consistent increases over time in their abstainer self-concept, and smokers showed increases followed by decreases to pretreatment levels. Clinical implications are discussed.

Adult↗
PubMedDate not supplied

The role of weight concern and self-efficacy in smoking cessation and weight gain among smokers in a clinic-based cessation program.

Although the majority of smokers are concerned about postcessation weight gain, few studies have investigated the prospective relationship between weight concern and smoking and weight outcomes, or a mechanism by which concern is related to these outcomes. We investigated the prospective role of smoking-specific weight concern in smoking cessation and weight gain among participants in a smoking-cessation clinic, and we hypothesized that domain-specific self-efficacy would be a mediator of these relationships. While weight concern did not prospectively predict smoking status, increased weight concern predicted weight gain at the end of treatment and at 3-month follow-up. Self-efficacy for preventing postcessation weight gain mediated this relationship; lower levels were related to a greater likelihood of weight gain. Weight gain was found to be associated with subsequent relapse among abstainers. Implications and treatment recommendations are discussed.

Adult↗