Asunto(s)
Actitud Frente a la Salud , Pérdida Auditiva Conductiva/psicología , Simulación de Paciente , Estudiantes/psicología , Actividades Cotidianas , Adaptación Psicológica , Adolescente , Adulto , Niño , Preescolar , Pérdida Auditiva Conductiva/epidemiología , Pérdida Auditiva Conductiva/prevención & control , Humanos , Lactante , Tamizaje Masivo , Persona de Mediana Edad , Factores de Riesgo , Servicios de Salud Escolar , Patología del Habla y Lenguaje/educaciónRESUMEN
Binding and phagocytosis of rat erythrocytes by liver and peritoneal macrophages were studied with a radioactive in vitro assay which yields quantitative data. Partial removal of sialic acids from the erythrocytes by Vibrio cholerae sialidase resulted in a marked increase of binding of the red cells by both liver and unstimulated peritoneal macrophages. Peritoneal macrophages stimulated by thioglycolate or starch, however, did not differentiate between control and desialylated erythrocytes. By inhibition experiments it was confirmed that rat peritoneal macrophages bind homologous sialidase-treated erythrocytes via a beta-D-galactose-specific lectin on the macrophage surface. While this attachment already occurs in buffer, serum was required for the subsequent phagocytosis. The possible involvement of factors of the complement system in the phagocytosis step was evidenced by a marked decrease of phagocytosis after heat inactivation of the serum. Based on these experiments, we propose a model of a two-step mechanism for the uptake of sialidase-treated erythrocytes by macrophages, comprising both the lectin and a receptor for serum components.
Asunto(s)
Eritrocitos/fisiología , Macrófagos/fisiología , Neuraminidasa/farmacología , Fagocitosis/efectos de los fármacos , Animales , Células Cultivadas , Femenino , Cinética , Hígado/fisiología , Macrófagos/efectos de los fármacos , Masculino , RatasRESUMEN
A clonal line of highly oncogenic "spontaneously transformed" mouse cells (T AL/N clone 3) was transformed in tissue culture by simian virus 40 (SV40) and subsequently recloned. The clone of SV40-transformed cells (subclone 1) expressed SV40-specific T (nuclear) and transplantation antigens but was 100 times less tumorigenic than the parent T AL/N clone 3 cells. When large numbers of subclone 1 cells (10(4)-10(5)) were injected into syngeneic AL/N mice, tumors were produced. From the tumors, cell lines were established in culture, all of which were consistently negative for T antigen. Tumor lines tested were found not to contain SV40-specific transplantation antigen and had again become highly tumorigenic. The original subclone 1 cells contained about one copy of SV40 DNA per diploid amount of cell DNA, as well as RNA complementary to the early region of the SV40 genome. The T antigen-negative cells from tumor line 124 contained approximately 0.5 copy of SV40 DNA per diploid equivalent and did not synthesize any detectable virus-specific RNA. Reassociation kinetic analysis with restriction enzyme fragments of viral DNA demonstrated that the cells from tumor line 124 (and also the clones of this line) had lost DNA sequences predominantly from the early region of the SV40 genome. The results indicate that a set of stably integrated SV40 DNA sequences can be present in a cell without the expression of viral antigens.
Asunto(s)
Antígenos Virales , Transformación Celular Neoplásica , Genes Virales , Virus 40 de los Simios/inmunología , Línea Celular , Transformación Celular Viral , Células Clonales , Enzimas de Restricción del ADN/metabolismo , ADN Viral/biosíntesis , Cinética , ARN Viral/biosíntesisRESUMEN
In an already tumorigenic spontaneously transformed mouse cell, after further transformation by SV40, the virus-specific antigenic function becomes dominant. By transplantation into syngeneic mice SV40 antigen negative revertant tumour cells can be selected out.