Helmut A. Gordon

Diphenylhydantoin Sodium (Dilantin) as a Caries Retarder

Rats that had their mandibular first molars silk-ligated and that were fed chow with diphenylhydantoin sodium (Dilantin) developed less caries than rats that were not fed Dilantin. The retarding effect of Dilantin was enhanced by the cleanliness of the environment in which the animals lived.

Caries Due to Food Retention in Nonsusceptible Rats Fed a Noncariogenic Diet

Ligation of mandibular first molars in Fischer rats resulted in extensive food retention and massive caries, although the rats were fed a high fluoride, noncariogenic diet. These experimental conditions were suggested as a model to study the relationship of food retention to caries.

Bidirectional Permeation of Water and Amino Acids in the Cecum of Germfree Rats

The purpose of this work was to study transport across the cecal wall of germfree animals which has been found altered in previous experiments. Germfree (gf) and conventional control (conv) male Fisher (Ch.R., CD-F) rats, 8–10 months old, fed sterilized 5010C (water expt) or L-462 (amino acid expt) diets were used in urethane anesthesia (150 mg/100 g bodyweight). The labels employed were tritiated water, 14C UL glycine and serine in doses of 10 μC/rat. Absorption was studied by injection of the label into the intact cecal sack which was ligated at the emergence of the ileum and of the colon, and by the successive recovery from its contents. Efflux into the cecum was observed after injection into the saphenous vein. The duration of the experiment averaged 20 minutes. The corrected body weight was approx. 300 g in the 24 gf and 26 conv rats used to date in this series. The ceca of the gf rats were considerably enlarged (avg. 11% of the body weight); their contents were rather liquid (avg. 18% dry matter) and their osmolality was similar to that of blood plasma (in mOsm, mean, blood plasma 335 ± 10, gf cecal contents 326 ± 24). The results indicated that the efflux of tritiated water from blood into the cecum was increased in the gf group in comparison to conv controls.

Effects of tobacco smoke inhaltion on the tracheo-bronchial microflora of rats

The purpose of work was to study the effects of tobacco smoke on the airway flora in rats. A study on the regional distribution, total numbers and composition of the flora suggested the following: (a) Subacute smoke exposure intensified the penetration of the flora into deeper, normally sterile portions of the airways. (b) On smoking, the predominantly D. pneumoniae type flora of normal rats was found to shift to a form in which Hemophilus sp. was most frequent. (c) Exposure to low or high nicotine content cigarettes did not particularly modify these results.

Blood Flow, Collagen Components of Oral Tissue and Salivary Kallikrein in Young to Senescent, Germfree and Conventional Rats

In oral tissues of rats, progress of age resulted in a gradual reduction of regional blood flow and in decreased levels of eluable (labile) hydroxyproline from the collagen component. These were paralleled by an increment of salivary kallikrein. The presence of the microbial flora in the oral cavity, portrayed by the comparison of conventional and germfree rats, caused an elevation of blood flow in all age groups, without exerting a marked effect on eluable hydroxyproline. In addition to aging and flora effects, the action of chronic hypoxia and of mechanical stress has been observed on the mentioned parameters. The presently used animal models and experimental design permit a critical study of etiologic agents and characteristic lesions of peridontal disease.

Effects of Age and Isolation on the Intestinal Flora of Mice

The gut flora of 4- and 24-month-old ICR mice has been studied in the following groups: (a) conventional mice held in the open environment, (b) conventional mice in germ-free-type isolators and (c) ge