Many popular dietary supplements are enriched in polyphenols such as the soy isoflavones, tea catechins, and resveratrol (from grape skins), each of which has been shown to have chemopreventive activity in cellular models of cancer. The proanthocyanidins, which are oligomers of the catechins, are enriched in grape seeds and form the basis of the dietary supplement grape seed extract (GSE). Evidence suggests that the proanthocyanidins may be metabolized to the monomeric catechins. This study was carried out to determine whether GSE added to rodent diets protected against carcinogen-induced mammary tumorigenesis in rats and whether this was affected by the composition of the whole diet. Female rats were begun on 5%, 1.25%, or 0% (control) GSE-supplemented diets at age 35 d. At age 50 d they were administered 7,12-dimethylbenz[a]anthracene (DMBA) in sesame oil at 80 mg/kg body weight. They were weighed and monitored weekly for tumor development until 120 d after DMBA administration. Administration of GSE in AIN-76A diet did not show any protective activity of GSE against DMBA-induced breast cancer. However, administration of GSE in a laboratory dry food diet (Teklad 4% rodent diet) resulted in a 50% reduction in tumor multiplicity. In similar experiments, genistein administered in AIN-76A diet also failed to show chemopreventive activity against the carcinogen N-methyl-N-nitrosourea; however, when administered at the same dose in the Teklad 4% rodent diet, genistein exhibited significant chemopreventive activity (44-61%). These results demonstrate that GSE is chemopreventive in an animal model of breast cancer; moreover, the diet dependency of the chemopreventive activity for both GSE and genistein suggests that whether or not a compound is chemopreventive may depend on the diet in which the agent is administered.

SilnlnlaryThe virulent Salmonella tl/phimurium strain WB600 carries the mviA allele of the gene mouse virulence A. As shown here, the virulent phenotype of WB600 is the result of a nonfunctional mviA gene. As compared to the functional allele mviA +, mviA increases virulence in Ity' mice, but not in Ity r mice. A specific BgllI site, mviA4185, between osraZ and gaIU, located at ~35 min on the salmonella chromosome, was within mviA. Insertion of an antibiotic cassette in the mviA4185 site of mviA § or the homologous mviA4093 site of mviA DNA resulted in virulence when either cassette was recombined into the chromosome. When mviA and mviA + were both expressed in the same strain with one carried in the chromosome and the other on a plasmid, avirulence was dominant. Replacement of the mviA allele of strain WB600 using P22 transductions of linked antibiotic cassettes cloned into the chromosome of virulent S. typhimurium strains (SR-11, TML, SLD44, C5, ATCC14028, Wl18-2, and WB600) showed that all but WB600 contained the avirulent mviA § allele. Southern hybridizations provided no evidence for a second mviA allele anywhere in the genome of the six non-WB600 strains.

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Homogeneous pesticin, a bacteriocin produced by Yersinia pestis, promoted rapid dose-dependent killing of Escherichia coli f but permitted residual generation of cell mass. Both growing cells and those blocked in net synthesis of nucleic acids or protein were converted by pesticin to osmotically stable spheroplast-like forms. Morphology and viability of cells starved for fermentable carbohydrate were not affected by pesticin. Similar spheroplast-like structures were formed from sensitive cells of Yersinia pseudotuberculosis, Yersinia enterocolitica, and Y. pestis.

Social workers and teachers in schools deal with families in distress. When a child is having trouble in school, families will respond in their preferred style of dealing with problems. The challenge for social workers and teachers is to understand the meaning behind how the family copes with the distress. Professionals typically have been taught traditional models of family dynamics that identify or label coping styles as either functional or dysfunctional. The authors introduce school-based professionals to the Family Distress and Family Outreach models, which emphasize an appreciation for the family's ability to cope with distress in ways that are consistent with its goals and values. The authors provide a framework for developing and maintaining working relationships with students' parents on the basis of the Family Outreach Model.