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Biomedical subjects

J D Wilson

Publications and source records attributed to J D Wilson.

At least 469 records · Page 26Linked to original sources
PubMed1970

Dihydrotestosterone in prostatic hypertrophy. II. The formation and content of dihydrotestosterone in the hypertrophic canine prostate and the effect of dihydrotestosterone on prostate growth in the dog.

Three types of studies have been performed in immature, mature, and hypertrophic prostate glands of the dog. First, the concentrations of testosterone and dihydrotestosterone have been measured in the three types of gland. Dihydrotestosterone was the predominant hormone recovered in all prostates studied and was present in approximately five times higher concentration in the hypertrophic as compared to the other types of dog prostate. Second, pharmacological doses of dihydrotestosterone were administered to castrated dogs for 9 months and resulted in a distinct acceleration of prostatic growth as compared to testosterone treatment. Third, the rates of formation and degradation of dihydrotestosterone were measured in normal and hypertrophic tissue and were found to be essentially the same. These observations suggest that dihydrotestosterone accumulation may be causally linked to the development of canine prostatic hypertrophy. However, the mechanism by which dihydrotestosterone accumulates in the prostate remains to be determined.

Aging↗
PubMed1969

The conversion of testosterone to 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone) by skin slices of man.

The conversion of testosterone-1,2-(3)H to dihydrotestosterone by slices of human skin obtained from various anatomical sites in 112 normal subjects and three individuals with the syndrome of testicular feminization has been measured under standardized conditions. Very low rates of dihydrotestosterone formation were observed in sites obtained from the mons or from miscellaneous areas of the trunk and limbs of the control subjects. The mean rates of conversion were very high, however, in slices of skin obtained from several perineal sites (labia majora, scrotum, prepuce, and clitoris). Furthermore, as measured here, the rate of dihydrotestosterone formation by prepuce rises during the 3 months after birth and then falls progressively thereafter, reaching a level in the adult that is almost as low as that observed in the slices of nonperineal skin from all ages. In the patients with testicular feminization dihydrotestosterone formation by slices of skin obtained from the mons was within the normal range, whereas the rates observed in labia majora were lower than the average values obtained in the normal subjects.

Adolescent↗
PubMed1968

Cholesterol synthesis in the squirrel monkey: relative rates of synthesis in various tissues and mechanisms of control.

Cholesterol synthesis has been extensively investigated in various tissues of lower mammals; however, there is little specific information concerning cholesterologenesis in the primate. Furthermore, experiments in whole animals suggest that important differences may exist in the features of cholesterologenesis in the dog and rat versus the monkey and man. Using the new world squirrel monkey, therefore, we performed the present studies to determine the rates of cholesterologenesis in various tissues per unit weight, to define the relative rates of whole organ synthesis, and to evaluate the operation of control mechanisms in these tissues.In control animals fed a low cholesterol chow diet, the liver and ileum were the two most active sites for cholesterologenesis followed, in order, by the colon, esophagus, and proximal small bowel. Rates of synthesis in 10 other tissues tested were considerably lower than these found in the gastrointestinal tract. When rates of whole organ synthesis were calculated, three tissues, i.e., liver, bowel, and skin, accounted for 92% of the total demonstrable synthetic activity.Following cholesterol feeding utilizing either a solid chow or liquid formula diet, marked suppression of hepatic cholesterologenesis occurred while synthesis in other organs remained essentially unaltered. Similarly, fasting animals for periods up to 96 hr resulted in suppression of synthesis in the liver, but not in various levels of the intestine. Finally, biliary diversion for 48 hr caused a twofold increase in hepatic cholesterologenesis and a six- to eightfold increase in sterol synthesis in the small but not the large intestine.

Journal Article↗
PubMed1968

Biosynthetic origin of serum cholesterol in the squirrel monkey: evidence for a contribution by the intestinal wall.

The possibility that the intestinal wall serves as a biosynthetic site for serum cholesterol has been examined in two types of studies in the squirrel monkey. First, animals were fed cholesterol in order to inhibit cholesterol synthesis in the liver, and the intestinal lymph ducts were cannulated. After the administration of acetate-2-(14)C it was possible to demonstrate that cholesterol synthesized by the intestinal wall enters intestinal lymph and thereby in the intact animal enters the circulating pool. Second, an attempt to quantitate the significance of this intestinal contribution has been made in animals fed cholesterol-3-(3)H and injected with cholesterol-4-(14)C for long periods. By an application of the technique of analysis utilizing the isotopic steady state we estimated as a minimal value that in the squirrel monkey 1.5-2.0 mg of cholesterol synthesized in the intestinal wall reaches the circulation each day.

Journal Article↗
PubMed1968

Bile salt and micellar fat concentration in proximal small bowel contents of ileectomy patients.

Studies were carried out to test the hypothesis that abnormal bile salt metabolism (interruption of the enterohepatic circulation) is responsible for steatorrhea in patients with ileal disease and (or) ileectomy.Duodenal bile salt concentration after a single, standard meal eaten at 8 a.m. was measured in 8 patients with ileectomy steatorrhea and compared with 11 normal control subjects and 7 hospitalized patients without gastrointestinal disease. Mean bile salt concentration was approximately half normal in the ileectomy group, but some of the patients fell well within the normal range, even on repeat studies. However, it was shown that the second and third meals eaten during a single day were associated with a marked depression of duodenal bile salt concentration in ileectomy patients, which suggested that the first meals in these patients flush out a large fraction of the bile salt pool. Simultaneously measured turnover studies with taurocholate-(14)C showed at t((1/2)) of 3.1 hr in these patients compared with 29.5 and 32 hr in two control subjects, proving that the enterohepatic circulation had indeed been interrupted by ileectomy. Hepatic synthesis can apparently partially reconstitute the bile salt pool during the overnight period. Additional studies were carried out to determine the relation between bile salt and micellar fat concentration in proximal small bowel contents after ingestion of the same standard meal. Below a bile salt concentration of 1.7 mg/ml, less than 0.8 mg/ml of lipid existed in the micellar phase of intestinal contents, whereas when bile salt concentration exceeded this level the amount of fat in the micellar phase rose progressively. Only 1 of 11 samples from three ileectomy patients had a micellar fat concentration > 0.8 mg/ml, whereas 33 of 42 samples from control subjects had micellar fat concentration > 0.8 mg/ml.Thus, abnormally low duodenal bile salt concentration during at least a portion of the day, with the associated depression of micellar fat, appears to be a major cause of decreased fat absorption in patients with ileectomy steatorrhea.

Adult↗