C. T. G. King

Collagen synthesis in the secondary palate of the developing rat.

Abstract The presence of hydroxyproline in whole rat foetuses and isolated palates was used to calculate collagen synthesis from the 13th day of gestation to the first neonatal day. In the palate the amount of collagen per unit dry weight increased significantly during the gestational period just prior to and during palatal closure, while a much greater rate of increase was noted after closure during the period of bone formation. In the whole foetus, the amount of collagen per unit dry weight was similar to the values observed in the palate during the period prior to and during closure, while a marked difference was noted at later gestational stages. The total amount of collagen in the palate and foetus increased in an exponential manner during the time of palatal closure.

Chlorcyclizine produced cleft palate in the ferret (Mustela putorius furo)

THE SUSCEPTIBILITY of rat and mouse embryos to the teratogenic action of chlorcyclizine has been shown by KING and his co-workers (KING, 1965; STEFFEK, 1966). The spectrum of congenital malformations for both these species included clefts of the secondary palate. The species susceptibility of the ferret, a non-rodent, to this agent was investigated and the results are presented in this report. Ferrets were mated at a commercial source (Gilman Marshall, North Rose, New York) and shipped the following day which was recorded as the first day of gestation. Upon arrival at the laboratory, the pregnant ferrets were maintained with a minimal amount of handling for at least a two week period. The maternal diet during this and the subsequent periods of experimentation consisted of fresh horse meat, beef liver, pulverized chick-egg shell, cod liver oil and homogenized pasteurized milk. On days 14-21, 16-23 and 18-25 of gestation, one cm3 of ground chlorcyclizine tablets in water (30 mg/kg) was administered subcutaneously to the animals. One additional ferret received a similar subcutaneous injection of chlorcyclizine in a dosage of 40 mg/kg from the 15-25 gestational days. The control animals consisted of three groups which received either the same volume of saline (two ferrets), drug excipient (five ferrets) or no injections (three ferrets) during the experimental period. The animals were maintained until day 35 of gestation (7 days before expected parturition) and killed by ether anesthesia. The f&uses were removed by laparotomy and examined for grosscongenital malformations. The results are presented in Table 1. One fcetus exhibiting a spontaneous malformation of exancephaly was obtained from the control non-injected group. No spontaneous malformations were seen in either the sham-injected saline or excipient group. Three spontaneous resorptions were noted in the control non-injected series. Maternal loss of hair and fcetal resorptions were observed in one pregnant ferret treated with 40 mg/kg of chlorcyclizine from the 15th through 25th days of gestation. As the dosage was reduced and the time of drug administration restricted to other

Major components of the primary and secondary dentition of miniature and duroc swine fed normal vs. low phosphorus diets

Abstract The ash, calcium, phosphorus, magnesium and carbon dioxide were determined in the enamel and dentine of individual permanent and deciduous teeth of Duroc and Miniature (Pittman-Moore) swine. At weaning age the pigs were fed three different diets, which varied in composition and particularly in content of calcium and phosphorus. An objective of the study was to observe the effect of a low phosphorus diet on tooth chemistry. As an experimental animal swine have the advantage of having a primary and secondary dentition, and the dietary regimen, therefore, was effective throughout the major period of calcification of the permanent teeth. The results indicate no effect of low phosphorus diets on the major components of enamel and dentine in any of the teeth, permanent or deciduous. All the teeth were quite uniform in content of the elements analysed.

Carbon Dioxide Induced Acidosis in Pregnant Rats and Caries Susceptibility of Their Progeny

Summary Respiratory acidosis in the rat induced by exposure to 30% carbon dioxide in 70% oxygen previous to the 10th day of gestation significantly increased the severity of dental caries in the offspring subsequently fed a cariogenic skim milk diet. This treatment did not have any significant effect when applied after the 15th day of pregnancy.