RESUMEN
The pR plasmid, which enhances the survival of Escherichia coli C600 exposed to UV light by induction of the SOS regulatory mechanism, showed the same effect when it transformed mouse LTA cells (tk-, aprt-). With Tn5 insertion mutagenesis which inactivates UV functions in the pR plasmid, we recognized two different regions of the plasmid, uvp1 and uvp2. These pR UVR- mutants exhibited the same effect in LTA transformed cells, demonstrating that resistance to UV light, carried by the pR plasmid, was really due to the expression of these two regions, which were also in the mouse cells. Statistical analysis showed that the expression of the uvp1 and uvp2 regions significantly increased (P less than 0.01) the survival upon exposure to UV light in mouse cells and bacteria. These results might suggest the presence of an inducible repair response to DNA damage in mouse LTA cells.
Asunto(s)
Daño del ADN , Escherichia coli/genética , Plásmidos , 4-Nitroquinolina-1-Óxido/farmacología , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Enzimas de Restricción del ADN , Elementos Transponibles de ADN , Escherichia coli/efectos de los fármacos , Escherichia coli/efectos de la radiación , Ratones , Hibridación de Ácido Nucleico , Rayos UltravioletaRESUMEN
The LA-D cells, obtained by cotransformation of LTA mouse cells (tk- aprt-) with pR plasmid and with tk gene as selective marker, are significantly more resistant to UV light and 4-nitroquinoline-N-1-oxide than LTA control cells. In this work, we report that the LA-D cells exhibit different degrees of response to various DNA-damaging agents: wild-type survival to mitomycin, increased sensitivity to bleomycin, cis-diamminedichloroplatinum and N-methyl-N'-nitro-N-nitrosoguanidine. The pR plasmid could, therefore, play an important role in the DNA-repair mechanisms that modulate the cytotoxic effect of the DNA-inhibitory agents. The possible interactions between pR plasmid products and the different repair enzymes involved are discussed.
Asunto(s)
Bleomicina/toxicidad , Cisplatino/toxicidad , Daño del ADN , Metilnitronitrosoguanidina/toxicidad , Mitomicinas/toxicidad , Plásmidos , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Mitomicina , Timidina Quinasa/genética , Transformación Genética , Rayos UltravioletaRESUMEN
Ataxia telangiectasia (AT) cells are known to be hypersensitive to ionizing radiations and to drugs such as bleomycin and epipodophyllotoxin VP16, a topoisomerase II poison. Both of these produce DNA double-strand breaks even if through different mechanisms. In this work we analyzed the sensitivity to bleomycin and to epipodophyllotoxin of AT cells after transfection with pR plasmid. This plasmid, interacting with bacterial SOS repair pathways, expresses itself in mammalian cells conferring cell resistance to the SOS inducers UV and 4NQO and cell sensitivity to different drugs such as bleomycin. This effect is presumably due to the interaction of pR products with double-strand breaks. Our findings indicate that pR plasmid, in both AT lines tested (AT5BIVA fibroblasts and ATL6 lymphoblasts), expresses itself (increasing UV protection) and amplifies the already enhanced AT cell sensitivity to both bleomycin and VP16.
Asunto(s)
Ataxia Telangiectasia/genética , Bleomicina/farmacología , Daño del ADN , Reparación del ADN/genética , Etopósido/farmacología , Transfección , Línea Celular Transformada , Supervivencia Celular/genética , Aberraciones Cromosómicas , Reparación del ADN/efectos de los fármacos , Reparación del ADN/efectos de la radiación , Fibroblastos/efectos de los fármacos , Fibroblastos/efectos de la radiación , Herpesvirus Humano 4 , Humanos , Linfocitos/efectos de los fármacos , Linfocitos/efectos de la radiación , Plásmidos/genética , Respuesta SOS en GenéticaRESUMEN
Griffith psychometric test has been experimented on a group of 20 healthy newborn infants, monitored during their 1st year of life with quarterly check-ups. It was clear that the development general rates were constantly higher than the original values reported by the English author. In particular, in 12 months old infants, the rates appeared significantly higher than the rates observed on the same Italian specimen in past periods. A transverse and longitudinal study of the psychomotor development of subjects included in the specimen has given the opportunity to verify some of his features. The development outlines, traced by employing the average rates relevant to the 5 different aspects monitored (motor, personal-social, language, eye-hand co-ordination, practical reasoning), appeared to be well-balanced, that is without dissynchronisms between the different scales. The only exception being the scale of the social behaviour, were the average rates appear to be sensibly higher at every age. Individual development outlines, on the contrary, appeared to be disjointed in all aspects (except for 4 cases). In the longitudinal analysis then, some noteworthy oscillations in both general and partial rates, were observed among the controls carried out in subsequent periods in all the subjects.
Asunto(s)
Desarrollo Infantil , Lactante , Desempeño Psicomotor , Femenino , Humanos , Estudios Longitudinales , Masculino , PsicometríaRESUMEN
It has been recently reported that the pR plasmid enhances the UV survival in E.coli c600. In order to test whether this function may be expressed also in mammalian cells, LTA (tk- aprt-) mouse cells were cotransformed with pR plasmid DNA and ptk1 plasmid as selectable marker. Tk+ transformants were analyzed for their UV survival and for the presence of pR DNA sequences by blot-hybridization. The results show a correlation between the enhanced UV survival and presence of pR DNA sequences in cotransformed LTA mouse cells.
Asunto(s)
Escherichia coli/efectos de la radiación , Plásmidos/efectos de la radiación , Transfección , Rayos Ultravioleta , Adenina Fosforribosiltransferasa/genética , Animales , Secuencia de Bases , Enzimas de Restricción del ADN , Escherichia coli/genética , Células L/enzimología , Ratones , Hibridación de Ácido Nucleico , Fenotipo , Timidina Quinasa/genéticaRESUMEN
Presentamos una revisión de 5 años sobre los casos de tuberculosis (TBC) infantil registrados en el Hospital Interzonal Especializado Materno Infantil "Victorio Tetamanti" de la ciudad de Mar del Plata, desde enero de 1990 hasta septiembre de 1995. Se analizó la tendencia de la enfermedad, encontrando un incremento superior a lo esperado que coincide con cifras del ámbito de la provincia de Buenos Aires y del país. Se observó que la población afectada presentó 60 por ciento de formas pulmonares moderadas y 40 por ciento de formas graves, correspondiendo un 25 por ciento a formas extrapulmonares. Se registra desde 1993 la asociación de TBC infantil con el VIH, casi todos menores de 12 meses de edad, alcanzando desde entonces y hasta 1995, 10 por ciento del total de casos. Se obtuvo confirmación bacteriológica en el 20,3 por ciento y por histopatología en el 7,6 por ciento, con un índice de certificación diagnóstica del 23,6 por ciento. El índice de abandono de tratamiento fue del 13,9 por ciento. La mayoría de recibía tratamiento en forma autoadministrada. La mortalidad fue del 7,6 por ciento (6 casos), correspondiendo la mitad a niños con SIDA