P.E. Ross

Clofibrate therapy and gallstone induction.

Two hundred consecutive patients, referred to a clinic established for the management of serum lipid disorders, were studied to assess the prevalence of gallbladder disease: 163 patients agreed to cholecystography of whom 23 had gallstones; 5 other patients had had cholecystectomy. There was a strong associction between clofibrate therapy and gallstones, which were found in 9 of 18 patients. Fifty-six patients with normal gallbladders had duodenal bile analyzed for lipid composition, and results were compared with those from 15 other patients with gallstones but normal serum lipids. Bile in hyperlipidemia and normolipidemic controls contained less cholesterol (9.21±3.48 mol/100 mol) than in clofibrate-treated patients (13.33±3.48 mol/100 mol, P<0.01), and in gallstone patients with normal serum lipids (11.87±4.52 mol/100 mol). There was no relationship demonstrable between patterns of hyperlipidemia or ischemic heart disease and the presence of gallbladder disease. There was also no association between biliary lipid composition and serum lipids or low-animal-fat diet. It is concluded that clofibrate therapy markedly increases biliary cholesterol content and is a potent lithogenic agent in patients not otherwise especially prone to gallstones. Since its role in prevention of ischemic heart disease is now uncertain, its continued wide use warrants close scrutiny.

Characteristics of cholesterol absorption by human gall bladder: relevance to cholesterolosis.

The characteristics of cholesterol uptake by 83 human gall bladders (obtained at cholecystectomy) were studied with a modified Ussing technique. Real and artificial biles labelled with 14C-cholesterol and 3H-dextran (the latter to correct for adherent mucosal bile) were used; all gall bladders absorbed cholesterol (average 3.5 nmol/cm2/minute). Recovery of the absorbed cholesterol from the tissue showed that about 4% was esterified over 60 minutes. In artificial bile the rate of absorption of cholesterol increased as the bile saturation index rose, but became constant once supersaturation was achieved. In contrast, supersaturated real bile permitted greater absorption of cholesterol, possibly due to enhanced cholesterol solubilisation. Preincubation of gall bladder tissue in sodium cyanide (5 mM) caused a 30% reduction in cholesterol uptake indicating that, although absorption is predominantly a passive process, there is a partial active component. There were no pronounced differences in the rate of cholesterol absorption as gall bladders became more diseased, but there was a reduction in the amount of cholesterol ester formed.

The estimation of phospholipids in bile

Total and lipid phosphorus were measured in the duodenal aspirate of 24 fasting subjects following an injection of cholecystokinin. The lipid phosphorus values were lower than the total phosphorus, a difference most pronounced in dilute samples. Storage at -20 degrees C over 4 weeks resulted in a loss of over 50% lipid phosphorus. Such alterations in the lipid phosphorus affected the calculation of biliary phospholipid and hence the saturation index of cholesterol in bile causing it to be erroneously elevated. It is concluded that analysis of bile samples should be undertaken on freshly obtained samples and include a preliminary step for the extraction of lipids.

COMPARISON OF FIXED DOSES OF CHENODEOXYCHOLIC ACID FOR GALLSTONE DISSOLUTION

96 patients with gallstones have been treated for up to four years with chenodeoxycholic acid in daily doses of 500, 750, or 1000 mg. None of the patients started on 500 mg daily showed complete gallstone dissolution. 8 out of 41 patients on 750 mg daily had complete dissolution of their radiolucent gallbladder stones after six or more months, and a further 4 showed partial dissolution. 5 out of 28 patients on 1000 mg daily had complete dissolution of their radiolucent gallbladder stones after at least six months, and a further 9 showed partial gallstone dissolution. The mean duration of therapy was greater on 750 mg than on 1000 mg/day (1.27 vs. 0.58 years), and when results were analysed after the first six months therapy the total response-rate was significantly greater for the 1000 mg dose (12 out of 28) than for the 750 mg dose (9 out of 41). The individual response of radiolucent gallabladder stones to therapy could not be predicted from stone size, weight of patient, dosage/kg, orchange in biliary lipids. Treatment of radiolucent gallstones with chenodeoxycholic acid should start at 1000 mg daily.

Radioimmunoassay of primary bile salts in serum.

Rapid, sensitive radioimmunoassays have been developed for the conjugated primary bile salts, cholate and chenodeoxycholate, using immunogens prepared by the mixed anhydride procedure. Antibodies produced showed equal specificity for glycine and taurine conjugates. Cross-reactivities were comparable with those from other published radioimmunoassays. The assays were routinely performed on unextracted sera and the concentrations correlated well with concentrations determined by gas-liquid chromatography. Accuracy, determined by the addition of bile salt to charcoal-extracted serum, and percision, determined by replicate analysis of a normal sample, were both less than +/- 10%. These figures are comparable with those obtained by both gas-liquid chromatography and other radioimmunoassays for bile salts. Normal sera were found to contain 0.49-1.32 mumol/l of cholate and 0.55-2.02 mumol/l of chenodeoxycholate. Serum concentrations in patients with liver disease were higher than this normal range. Three patients with mild liver distrubance were found to have one bile salt in the upper limit of normal, but in each case the other primary bile salt was outwith the normal range.

Cholesteryl esters in human gallbladder bile and mucosa

Cholesteryl esters, identified by thin-layer and gas-liquid chromatography followed by mass spectroscopy in a few cases, were found in all human bile samples analysed. The amount varied extensively both in absolute concentration and when expressed as a percentage of the total cholesterol present. In about 30% of samples, the percentage of ester exceeded 4% of total cholesterol but there was no clear association with the presence of cholesterol gallstones or pigment stones, nor was there any association with the lithogenicity of bile.

Homogeneous enzyme immunoassay of chenodeoxycholate conjugates in serum.

Abstract Enzyme immunoassay has been applied to the determination of conjugates of chenodeoxycholate in serum. The procedure does not require extraction of serum nor separation of antibody-bound from free antigen. These two factors reduce the analysis time to less than 5 h, with sensitivity comparable to that of radioimmunoassay. Results correlate well with values determined by radioimmunoassay ( r = 0.99, N = 14) and precision (± 6%, N = 8) compares favourably with reported values for radioimmunoassay.

Serum bile acids in patients with viral hepatitis.

Total and individual serum bile acid concentrations were studied in 18 patients with viral hepatitis. The initial high values returned to the normal range at approximately the same time as the conventional liver function tests. Chenodeoxycholic acid was the predominant bile acid initially, but cholic acid predominated as the disease resolved. All patients had proportionately less doexycholic acid than controls. It is concluded that the measurement of serum bile acid does not provide added information of value in the management of patients with viral hepatitis.

Ursodeoxycholic acid for the dissolution of radiolucent gall bladder stones.

In a prospective dosage response study of 84 patients with radiolucent gall bladder stones treated with ursodeoxycholic acid (UDCA), a dose of 500 mg daily was as effective as 1,000 mg daily. Complete dissolution of stones was achieved in 9 of 31 patients (29%) treated for at least 6 months with the lower dose, and in 7 of 33 patients (21%) on the higher dose. 4 patients in each group continue on treatment having shown partial gall-stone dissolution. When the two dosage groups were considered together, small stones dissolved more readily than larger ones and, after allowance for stone size, success rates were equal in obese and non-obese patients. Treatment with UDCA was well tolerated and significant adverse effects were not encountered.

125I Radioimmunoassay of serum ursodeoxycholyl conjugates

A radioimmunoassay for serum ursodeoxycholic conjugates using a 125iodine ligand has been developed. The bile acid was present in normal fasting serum (0.19 +/- SD 0.19 mumol/l, n = 24) and 2-hour post-prandial serum (0.8 +/- SD 0.8 mumol/l, n = 16). Gallstone patients undergoing oral ursodeoxycholic acid therapy had significantly higher post-prandial serum levels (21.5 +/- SD 14.0 mumol/l, n = 15) by radioimmunoassay. Gas liquid chromatography analysis indicated that in normal serum ursodeoxycholic acid was totally conjugated, whereas sera from gallstone patients contained a proportion as the free bile acid (10.2 +/- SD 8.1 mumol/l, n = 15). Following an oral dose of ursodeoxycholic acid, both unconjugated and conjugated forms of the bile acid appeared in the serum of healthy individuals.