Clinical analysis of our cohort leads us to define NBO as a distinct disease entity with three clinical presentations: acute NBO, chronic recurrent multifocal osteomyelitis or persistent chronic NBO. Diagnostic criteria were proposed to differentiate NBO from diseases with similar clinical presentation.

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Several in-situ chemical reduction methods were systematically evaluated in view of the formation of silver−latex composites, and in particular with respect to the task of coating colloidal latex spheres with uniform thin layers of silver. Such nanocomposite materials are of profound interest, due to their expected novel optical properties. The samples were investigated by transmission electron microscopy and UV−vis spectroscopy. A range of silver particle features was obtained, including even and uniform silver coatings in the nanometer size regime on the latex particles.

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By inducing mouse thymomas with carcinogens and y-radiation, we have studied the potential of tumor DNA to induce foci in rodent fibroblasts. A high percentage of the tumors used transformed the cultured cells, and the oncogenic phenotype segregated with extra copies of the c-ras gene family. There appears to be selectivity in the activated gene because so far all analyzed tumors induced by carcinogen have activated the N-ras gene, and those induced by radiation have activated the K-ras gene. The K-ras gene is the cellular counterpart of the viral ras oncogene in Kirsten murine sarcoma virus, but the N-ras has not yet been found in a retrovirus. The transformed cells have a marked increase in expression of the oncogene at the RNA and protein level. This model system might be a powerful tool in the study of leukemogenesis.The study of thymic lymphoma development in inbred strains of mice is an excellent model system for tumor development. A defined set of protocols involving either radiation or various chemical carcinogens has been elaborated to induce reproducibly a high incidence of thymic lymphoma in treated mice (1-5), and the use of inbred laboratory strains provides a well-characterized genetic background.In the past few years, a powerful technique has been worked out to study the neoplastic process: high molecular weight DNA from several transformed cell lines and primary tumors "transforms" NIH 3T3 cells that are exposed to a calcium phosphate precipitate of DNA (6-12; for a review see ref. 13).Several genes from human tumor cell lines have been isolated (14-17), and the sequences responsible for transformation have been identified as cellular counterparts (c-ras) of the transforming genes of the viral ras family (18, 19) that were previously found in Kirsten and Harvey murine sarcoma viruses, designated K-ras and H-ras, respectively.Recently a report has appeared showing activation of the H-ras gene in carcinogen-induced (and subsequently transplanted) mouse skin carcinomas (20). We call activation of an oncogene the property of segregating with the transformed phenotype upon DNA-mediated gene transfer, although formal proof will come only after a change is demonstrated in the DNA sequence with respect to the normal gene. We report here induced activation of the N-and K-ras genes in murine tumors of the lymphohemopoietic system by means of carcinogen or -radiation. These findings should be instrumental in studying the early stages of carcinogenesis in this model in vivo system. MATERIALS AND METHODSInduction of the Tumors. Thymic lymphomas were induced by (i) intraperitoneal injection of mice with 30 mg of the chemical carcinogen N-nitrosomethyl urea per kg of body weight once a week for 5 consecutive weeks, starting with 35-to 60-day-old animals, and (ii) exposure at similar ages to whole-body y-ray doses of 150 rads once a week for 4 consecutive weeks. The mice used, derived from crosses between the inbred AKR and RF strains, had low incidence of spontaneous thymic lymphoma.Transformation of C...

No single test for Chagas' disease is sufficiently sensitive to prevent transfusion transmission of the disease in the urban centers of Brazil.

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