No abstract

Two of the distinguishable cell classes subcultured from human amniotic fluid were examined for their capability to produce human chorionic gonadotropin (hCG) as determined by radioimmunoassay. The class that predominates in most cultures used for prenatal genetic diagnosis, previously termed AF (for amniotic fluid), secretes hCG into the culture medium. Dermal fibroblasts do not, nor does another type of cultured cell from amniotic fluid, previously termed F because of a resemblance to fibroblasts. Primary AF cultures produce more hCG than do subcultures. Evidence that this hormone is intact hCG is provided by its immunoreactivity with antisera raised against the beta-subunit and against the intact molecule of hCG. Furthermore, a dose-response curve for hormone in culture medium is parallel to that of highly purified intact hCG. It is postulated that AF cultures are derived from fetal membranes and retain properties of trophoblast.

SUMMARYThe collagen produced by differentiated cells cultured from human amniotic fluid was characterized in two ways. By chain composition and by 4-hydroxyproline: 3-hydroxyproline isomer ratio, the collagen synthesized by F-type (fibroblast) cells was indistinguishable from that made by cultured fetal dermal fibroblasts. The predominant cells in young amniotic fluid cultures, termed AF-type, produced collagen with a lower isomer ratio, resembling that of basement membrane collagen. The chain composition, as determined by chromatography on carboxymethyl cellulose, varied for different cultures of the AF-type, but the major pattern was consistent with that of basement membrane collagen. On the basis of these characteristics, F cells are of fibroblast origin, whereas most AF cells are of a different origin either endothelial or epithelial. Other evidence (Megaw et al., 1977) suggests an epithelial origin for AF cells.Studies using human amniotic fluid cell culture as an aid to prenatal diagnosis are increasing in complexity. We began to investigate collagen synthesized by these cell cultures because of the need for prenatal diagnosis of inherited diseases affecting collagen. Initial studies in this laboratory had shown increased solubility of collagen produced by cultured dermal fibroblasts from Marfan syndrome compared with controls (Priest et al., 1973), and the question arose whether this or other disorders of connective tissue could be diagnosed in cultured amniotic fluid cells. Therefore, further studies were performed on collagen laid down in the cell layer and extracted by acid or neutral salt, or on collagen released into culture medium by two types of fetal cells cultured from amniotic fluid, F (fibroblast) and AF (amniotic fluid) types (Hoehn et al., 1974).We report here that the F and AF cells, distinguished from each other originally on the basis of morphology and growth characteristics, also differ biochemically in the types of collagen formed in culture. We also report another biochemical difference (Megaw et al

Compared to feeding basal (67%) cornstarch or 25% glucose or 25% sucrose diets, feeding a 15% cellobiose diet to rats for 4–5 weeks resulted in diarrhea, smaller body weight gains, greater small gut weight relative to body weight, greater absolute and relative weights of the cecum and of the colon plus rectum, and several differences in stomach weight. In a separate 4–4 1/2-week feeding experiment, the absolute and relative weights of the stomach in three dietary groups were in the order: 67% glucose > 67% sucrose > 67% cornstarch. Also 67% sucrose exceeded 67% cornstarch in absolute and relative small gut weights and in small gut weight: length ratio.

Eleven southeastern medical schools cooperated to evaluate nutrition knowledge and attitudes of medical students. This study complements previous reports of an examination of entering freshmen and seniors. Average knowledge scores for 165 students tested after basic sciences (preclinical) training in this study were 67 +/- 7% compared with 53 +/- 6% for freshmen and 69 +/- 8% for seniors. The upperclassmen's scores were higher than the freshmen's (p less than 0.001) and varied with the amount of required nutrition teaching. Only 13% of preclinical students perceived nutrition as important to their careers compared with 74% of entering and 59% of graduating students, suggesting that preclinical teaching reduces their sense of relevance of nutrition to medicine. These findings suggest that nutrition knowledge can be increased through preclinical coursework and that the knowledge level can be maintained through the clinical years. However, the positive attitude of freshmen toward nutrition is lost after preclinical training and is only partially regained after the clinical years.