Biomedical subjects

G R Onstad

Publications and source records attributed to G R Onstad.

40 records · Page 3Linked to original sources

PubMed1967

Fluid transfer in the everted human gallbladder.

The rates of fluid transfer across human gallbladders obtained at cholecystectomy for cholelithiasis were determined by the measurement of weight changes of everted preparations under controlled conditions. Active transport of fluid from the mucosal to the serosal surface was indicated since weight gain occurred with the same solution on both sides of the membrane and against hydrostatic, osmotic, and potential differences. With respect to sodium, the fluid transferred was isotonic to the bathing solutions. Metabolic inhibitors and temperature extremes inhibited weight gain. In addition, muscle contractions in this in vitro preparation were related to the rates and direction of fluid movement. Cholecystokinin increased muscle activity and caused weight loss in preparations that previously had gained weight. Norepinephrine caused weight gain or increased weight gain in all preparations tested. The direction of net fluid movement in the isolated everted human gallbladder was determined by the opposing forces of active mucosal transport and a filtration pressure generated by muscle contractions.

Biological Transport, Active↗

PubMedDate not supplied

The relationship of hemorrhoids to portal hypertension.

Records of 188 patients with documented portal hypertension were reviewed to determine the incidence of hemorrhoids as well as bleeding complications associated with this condition. The incidence of hemorrhoids among these patients was not increased compared to the normal population. Six of the patients with portal hypertension did, however, bleed massively from hemorrhoids. Elevated portal venous pressure is an important factor in those patients having severe hemorrhoidal bleeding. The presence of coagulation defects may also be of considerable importance.

Adult↗

PubMedDate not supplied

The non-bleeding visible vessel versus the sentinel clot: natural history and risk of rebleeding.

Non-bleeding visible vessel and sentinel clot are terms used interchangeably to describe protuberances in the base of ulcers that have recently bled, but a consensus as to their definition or natural history does not exist. In patients with severe ulcer hemorrhage, non-bleeding protuberances were classified as vessels, with or without a small attached clot, or as sentinel clots, according to a schema based on the appearance of the protuberance at endoscopy but not subjected to pathologic correlation. Endoscopic therapy was not performed at the index endoscopic evaluation, and natural evolution was prospectively documented with daily videoendoscopy. Eleven (46%) of 24 patients with non-bleeding protuberances had rebleeding. Independent classification by three authors concurred in 18 (75%) of 24 lesions. Ten (91%) of 11 vessels with or without attached clot rebled versus 0 (0%) of 7 sentinel clots and 1 (17%) of 6 lesions without unanimous classification (p < 0.01, vessels versus other groups). Rebleeding occurred in 5 (71%) of 7 nonpigmented (pale or white), 6 (38%) of 16 red or purple, and 0 (0%) of 1 black protuberances. In general, vessels persisted until rebleeding, whereas sentinel clots disappeared within 1 to 3 days. We conclude that nonbleeding protuberances in ulcer bases can be separated into vessels, which have a high risk of rebleeding, and sentinel clots, which have a low risk of rebleeding.

Blood Coagulation↗

PubMedDate not supplied

Measurement of fat absorption utilizing 131iodine-triolein and nonabsorbable radioactive markers.

To eliminate many of the practical problems inherent in the collection of feces and in the chemical determination of fecal fat, a radioactive marker (131Ba) was combined with a labeled fat (131l-triolein) to measure fat absorption in man. The ratios of radioactivity of 131Ba/131l in a prepared capsule and that found in a random "grab" stool specimen after oral administration of the capsule were compared to determine the amount of fat absorbed. In an initial 36 patients, this double-label technique accurately separated normal from abnormal fat absorption as determined by the usual methods of quantitative fecal fat measurement. Results in an additional 102 patients and in 26 normals accurately reflected their clinical states. In addition, in vitro studies demonstrated more complete recovery of added lipid (99 percent) by radioactive techniques than by chemical analysis (86 per cent). The double-label technique not only seems more accurate than usual quantitative fecal fat determinations, but also greatly simplifies the measurement of fat absorption in man by eliminating the need for special diets, quantitative stool collections, and chemical analysis of stool.

Barium↗