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Biomedical subjects

C Snyder

Publications and source records attributed to C Snyder.

At least 73 records · Page 4Linked to original sources

Prediction of IQ and language skill from perinatal status, child performance, family characteristics, and mother-infant interaction.

193 basically healthy working-class and middle-class mothers and their infants participated in a 4-year longitudinal study which focused on the relative potency of several clusters of variables for predictions of intellectual and language outcome during the preschool years. The major results were: (1) Measures of perinatal or infant physical status were extremely weak predictors of 4-year IQ or language. (2) Assessments of child performance were poor predictors prior to 24 months, but excellent predictors from 24 months on. (3) Assessments of mother-infant interaction and general environmental quality were among the best predictors at each age tested, and were as good as measures of child performance at 24 and 36 months in predicting IQ and language. (4) Measures of the family ecology (level of stress, social support, maternal education) and parent perception of the child, especially when assessed at birth, were strongly related to child IQ and language within a low-education subsample, but not among mothers with more than high school education. Patterns of prediction were similar for 48-month IQ and 36-month receptive language; predictions were notably weaker for 36-month expressive language.

Child Development↗

Vitamin A and the susceptibility of respiratory tract tissues to carcinogenic insult.

The influence of vitamin A on the development of chemically induced lung carcinomas in rats was investigated. Rats were maintained on low, "normal" and excess levels of retinyl acetate (RA). Respiratory tract-squamous carcinomas were induced by intratracheal injections of 3-methylcholanthrene (3-MCA). The carcinogen doses used ranged from 1.25 to 10.0 mg of 3-MCA. Serial sacrifices conducted during the first 20 weeks following carcinogen exposure showed that metaplastic lung nodules, presumed to be precursors of later appearing carcinomas, occurred earlier and at higher incidence in rats maintained on low levels of RA than in rats maintained on moderate or high levels of RA. The development of invasive pulmonary carcinomas was enhanced at all four carcinogen doses in rats receiving low levels of RA as compared to rats receiving moderate or high levels of RA. No consistent difference in lung cancer incidence existed between the groups receiving normal and high levels of RA. The data clearly show an increased susceptibility of vitamin A-deficient rats to develop chemically induced lung cancers. Possible mechanisms underlying this effect are discussed.

Animals↗

The influence of retinyl acetate on the postinitiation phase of preneoplastic lung nodules in rats.

The effects of retinyl acetate (RA) on the development of carcinogen-induced metaplastic lung nodules were investigated. Four mg of 3-methylcholanthrene were administered intratracheally to F344 rats maintained on a vitamin A-free diet and receiving 31.4 nmoles of RA per week by intragastric intubation. At 3, 5, and 10 weeks after intratracheal instillation of 3-methylcholanthrene, one group of 24 rats each was started on a weekly dose of 31,400 nmoles of RA; a control group was continued on the low-RA dose. Fifty-two weeks after 3-methylcholanthrene injection, the incidence of metaplastic lung nodules was found to be 3% in the combined high-RA-dose groups as compared with 42% in the low-RA-dose group. It is therefore concluded that RA has a significant effects on the postinitiation phase of preneoplastic lung nodules in rats.

Animals↗

The investigation of Horace Green.

Horace Green is often regarded as the "Father of American Laryngology." Original in his thinking, innovative in his methods, outspoken in support of his views, Green was often violently criticized by his contemporaries. One medical society attempted to force his resignation as a member. In 1855, the New York Academy of Medicine ordered an investigation of Green and his methods. Honest to the core of his being, Green welcomed the investigation and cooperated in every way possible. Although the investigators' findings were inconclusive, time did bring vindication to Green and to some of his views.

Animals↗

The suffix "caine".

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Anesthetics, Local↗