The effect of portacaval shunt on plasma lipids and tissue cholesterol synthesis in the dog.

Portacaval shunt (PCS) has been proposed as a therapy for hyperlipidemia; however, its lipid-lowering mechanism is unknown. In this study PCS was performed on ten mongrel dogs to measure its effect on plasma lipids and on the cholesterol synthesizing ability of the liver and intestines, the major indodenous cholesterol synthesizing tissues. Plasma was analyzed for total cholesterol (CHOL), triglycerides (TG), and the CHOL content of three plasma lipoprotein fractions. Jejunal, ileal, and hepatic cholesterol synthetic rates were determined by 14C-acetate incorporation to CHOL in tissue slices obtained at operation before PCS and 44 +/- 4.1 (S.D.) days after PCS. Plasma CHOL decreased by 18 +/- 7 (S.E.), 34 +/- 8 (S.E.), and 57 +/- 14 (S.E.) mg. per 100 ml. by 4, 6, and 16 weeks after PCS, respectively. TG decreased by 13 +/- 5 (S.E.), 27 +/- 5 (S.E.), and 30 +/- 9 (S.E.) mg. per 100 ml. at corresponding time intervals. Paired Student's test analysis of CHOL and TG changes are significant at the p less than 0.05 level. CHOL content of the three plasma lipoprotein fractions decreased correspondingly. Intestinal tissue CHOL synthesis rates changed only slightly. Hepatic synthetic rates increased by 30 to 40%; however, no synthetic rate changes were statistically significant at the p less than 0.05 level. PCS is associated with decreased in plasma CHOL [42% (see article)] AND TG [53% (see article)] in dogs up to 16 weeks following operation. Statistically significant changes in endogenous CHOL synthesis were not demonstrated by this study. The mechanism by which PCS affects plasma lipids in the dog is unknown as yet.

Gastric secretion and serum gastrin in human small bowel bypass.

Jejunolieal bypass (JIB) patients provide a unique opportunity to study the relationship between small bowel loss and gastric secretory function. Preoperatively, and approximately one year postoperatively, measurements of gastric secretion were taken in 37 patients who underwent JIB for massive obesity. Basal acid output increased by 0.52 plus or minus 0.35 mEq/hr (P greater than.2), and peak stimulated acid output increased by 1.99 plus or minus 0.96 mEq/30 min (P smaller than .05). A separate group of 26 postoperative and 17 preoperative (control) JIB patients had fasting serum gastrin levels measured by radioimmunoassay. Postoperative patients had levels of 37 plus or minus 5 pg/ml, and control patients had levels of 36 plus or minus 4 pg/ml (P greater than .5). We conclude that following JIB for obesity, there is no significant change in basal acid secretion or in serum gastrin. There is a small, but statistically significant, increase in peak stimulated acid output. We currently find no clinical correlation with this change.

Mortality and gastrointestinal surgery in the aged: elective vs emergency procedures.

Elderly patients are often viewed as high-risk surgical candidates. Consequently, elective surgery may not be performed, with the result that a potentially treatable disease process may develop into an acute catastrophic event. We question the validity of this approach. In our experience with 1,411 gastrointestinal (GI) surgical procedures performed between March 1972 and September 1979, 23.6% have been in patients older than 70 years of age. The operations were emergent in this age group 19.5% of the time. Despite the advanced age of these individuals, the overall operative mortality for 269 elective procedures was 6.7%. For the 65 patients aged 70 years or older who underwent emergency procedures, the operative mortality was 20%. While elective GI surgery in the elderly has a significant risk, death is almost always the result of an associated disease (pulmonary, renal, or cardiac). Emergency procedures in the elderly indeed carry greater risk, statistically the same as in the 50- to 69-year-old group. Death is frequently related to an acute process complicating a treatable disease.

Vitamin B12 absorption following human intestinal bypass surgery.

Adaptation of vitamin B12 absorption by small intestine has been suggested by experimental and clinical studies. Five partial ileal bypass patients and ten jejunoileal bypass patients were studied for adaptation of B12 absorption following surgery. Adaptation of vitamin B12 absorption could not be demonstrated in either group. Few of the patients on an individual basis demonstrated adaptation. Parenteral B12 should be given to all patients who undergo bypass surgery unless evidence of persistent normal B12 absorption has been obtained.

Combined hypolipidemia of portacaval transposition and ileal resection in the dog.

The effects of portacaval transposition in combination with exclusion of the distal part of the intestine upon the plasma cholesterol and triglyceride levels was studied in dogs. The dogs tolerated distal intestinal resection, portacaval transposition and their combination well; survival and weight maintenance probably being superior to that of dogs having a standard end-to-side portacaval shunt. Plasma triglyceride levels significantly decreased after portacaval transposition and after intestinal resection; an additional and significant lowering of triglyceride levels was observed after a combination of these procedures. Portacaval transposition significantly lowered the plasma cholesterol level of dogs given a normal chow diet but did not protect them from diet-induced hypercholesterolemia. Distal intestinal resection did not significantly lower the plasma cholesterol level of nonhypothyroid, normocholesterolemic dogs fed regular chow but did protect them from dietary hypercholesterolemia. Portacaval transposition plus intestinal resection demonstrated the addition of these effects upon the plasma cholesterol level. The combination of a portal diversion operation and an intestinal exclusion procedure may provide a synergistic approach to lipid reduction.

Cholesterol pool sizes and turnover following portacaval shunt in the dog.

Portacaval shunt has been shown to be effective in lowering the plasma cholesterol level of both man and experimental animal. However, the primary mechanism which effects this reduction is unclear. We have measured the rapidly, and the slowly, miscible cholesterol pool sizes and the cholesterol production rate in mongrel dogs, with the animals in the cholesterol steady state, using 14C-cholesterol plasma decay curve analysis. Five control animals and three one year postoperative portacaval shunt animals with a 50 per cent plasma cholesterol level reduction were studied. No differences were demonstrated in either the cholesterol pool sizes or the production rate. These data have led us to postulate two hypotheses to explain the mechanism of the hypocholesterolemic effect of the portacaval shunt.

PET scans of abdominal malignancy.

Positron emission tomography (PET) with fluorine-18-2-d-deoxyglucose (FDG) currently is being integrated into clinical oncology because it provides unique functional information that can be applied to the management of cancer. In particular, it is useful for assessing tumor activity and growth, evaluating efficacy of therapy, and detecting tumor recurrence. Studies have demonstrated the value of whole-body PET-FDG imaging when staging and managing abdominal malignancy.