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Biomedical subjects

R D Soloway

Publications and source records attributed to R D Soloway.

At least 55 records · Page 3Linked to original sources
PubMed1978

Biliary lipid excretion in patients with pigment gallstones. A comparison with cholesterol gallstone patients.

Pigment gallstone patients are believed to have normal biliary lipid excretion. In order to measure this and to better understand cholesterol gallstone formation, the kinetics of biliary lipid excretion were studied in three patients who had been cholecystectomized for pigment gallstones and the results compared to those previously obtained in patients cholecystectomized for cholesterol gallstone. Pigment-stone patients had hyperbolic relationships between cholesterol and phospholipid outputs and bile salt output which were similar to those seen in cholesterol-stone patients. However, pigment-stone patients excreted more cholesterol and phospholipid at high bile salt output but approached those levels more gradually than cholesterol-stone patients. As a result, pigment-stone patients produced bile undersaturated with cholesterol at a lower bile salt output than cholesterol-stone patients, and thus they would be less likely to produce supersaturated bile during low bile salt output such as that occurring during an overnight fast. The data suggest that cholesterol-stone patients, in addition to excreting more cholesterol and less bile salts than normals, have a defect in the rate of lipid output in response to decreasing bile salt output.

Adult↗
PubMed1978

Factors affecting delivery of bile to the duodenum in man.

Studies utilizing balloon-occludable T or duodenal tubes in subjects with and without gallbladders were undertaken to identify the contribution of the gallbladder, the sphincter of Oddi, and bile salts to the delivery of bile to the duodenum. Patients with and without a functional sphincter of Oddi and with and without a gallbladder were compared. The presence of a functional sphincter of Oddi in duodenal tube patients reduced bile salt output by more than 67% from that observed in T-tube patients. When cholecystectomized and normal patients were compared using the duodenal tube, peak bile salt output was significantly increased in normal subjects, reflecting gallbladder contraction, but total bile salt output was not significantly increased suggesting that the gallbladder has a minor role in bile delivery. Exogenous infusion of cholecystokinin produced much more stable bile secretion than did endogenous release of cholecystokinin by intraduodenal infusion of essential amino acids. This rhythmic release of bile after endogenous cholecystokinin release was related to the concentration of bile salts in the intestinal lumen. Thus, delivery of bile to the duodenum is wave-like and is predominantly controlled by the sphincter of Oddi.

Adult↗
PubMed1977

Pigment gallstones.

Pigment gallstones are defined as any dark brown-to-black stone, consisting of calcium salts of bilirubin, phosphate, carbonate and other anions, and can be separated into carbonate- and noncarbonate-containing groups. Pigment stones predominate in the rural Orient, in cirrhosis, and in elderly United States patients undergoing cholecystectomy. Clinical associations include bile duct obstruction, stasis, and possibly hemolysis. Of pigment stones, 50% are radioopaque and account for two-thirds of all opaque stones. The concentrations of bile salts, phospholipids,, cholesterol, and total bilirubin in bile are similar to normal levels, but the concentration of unconjugated bilirubin is increased in the bile of some patients. Increased unconjugated bilirubin in bile may be caused by increased hydrolysis of excreted conjugated bilirubin. Unconjugated bilirubin is solubilized by bile salts, but the interaction is primarily nonmicellar. Ionized calcium and pH are important determinants of solubility. Sulfated glycoproteins, excreted in increased amounts in patients with cholelithiasis, may be the site of pigment stone precipitation because these compounds bind calcium salts tightly. E coli is frequently cultured from pigment stones in Japan but not in the United States; thus, bacterial beta-glucuronidase may be important in stone formation in Japan but probably not in the West. Stasis leads to increased calcium secretion and to increases in the concentration of sparingly soluble compounds that may then precipitate. Incomplete emptying of the gallbladder may result in the same concentration process. Unsaturated fats and chronic vagal stimulation cause pigment stone formation in animals. At present, surgery is the only treatment for pigment lithiasis.

Adolescent↗
PubMed1977

Pigment versus cholesterol cholelithiasis: identification and quantification by infrared spectroscopy.

We previously reported that 27% of 92 cholecystectomized patients had pigment stones (Am J Dig Dis 19:585-590, 1974). Using standard biochemical methods, we found that cholesterol accounted for an average of 77% of the dry weight of cholesterol stones, but that unconjugated bilirubin represented a mean of only 7% of pigment stones. This quantitation of pigment stones was limited because approximately 66% of their weight was insoluble. To characterize pigment and cholesterol stone composition further, we used infrared spectroscopy--a technique requiring neither crystallinity nor solubilization--to quantitate pigment, carbonate, and cholesterol in gallstones. Other organic and inorganic components of stones were measured by standard methods. By infrared spectroscopy, two types of pigment stones were identified: carbonate-containing and noncarbonate pigment stones. Carbonate pigment stones contained significantly more calcium, carbonate, and phosphate, but less pigment than noncarbonate stones. Compared to our initial report, the total measured components of all pigment stones were increased 6-fold from 10 to 63%. Cholesterol was the major component of cholesterol stones by chemical assay or infrared spectroscopy. Among five cholesterol stones with limited solubility, 80% of the insoluble residue was identified as cholesterol by infrared spectroscopy. This study extends our knowledge of pigment stone and cholesterol stone composition by the use of quantitative infrared spectroscopy in conjunction with standard biochemical methods; furthermore, it confirms that pigment and cholesterol stones differ in composition and form by different mechanisms.

Carbonates↗
PubMed1977

Factors affecting bilirubin excretion in patients with cholesterol or pigment gallstones.

To identify factors affecting bilirubin excretion, the effects of bile flow and bile salt excretion on bilirubin output into bile have been examined in normobilirubinemic, cholecystectomized patients with balloon-occludable, reinfusion T-tubes, 8 patients with cholesterol (CS) and 2 with pigment (PS) gallstones. Another patient with pigment gallstones, sickle cell disease (SS), and stable jaundice was studied to examine the mechanism by which an increased bilirubin load was excreted. Total bilirubin was almost entirely conjugated and excretion was related linearly to bile salt excretion PS and CS subjects; one-third of bilirubin excretion was bile salt independent and two-thirds was bile salt associated. In the SS patient 90% of the bilirubin excretion was independent of bile salt output. In PS and CS patients, bilirubin output was linearly related to bile flow, but the SS patient showed significant bilirubin excretion at low flow rates. CS and PS patients had similar patterns of bilirubin excretion, but the increased bilirubin load in the SS patient was excreted independently of bile salts. In the SS patient, unconjugated bilirubin output was hyperbolically related to bile salts output and represented a maximum of 3% of the total bilirubin output. The bile salt-independent excretion of conjugated bilirubin suggests that micelles were not required for transport into bile; whereas the hyperbolic relationship for unconjugated bilirubin and bile salt output, similar to that of the micellar lipids. cholesterol, and phospholipids, suggests interaction with micelles.

Adult↗
PubMed1976

Kinetic analysis of biliary lipid excretion in man and dog.

To understand better the mechanisms involved in biliary lipid excretion and to evaluate their role in cholesterol gallstone formation, the rates of biliary excretion of bile salts, cholesterol, and phospholipids were measured in two species, man and dog. Seven cholecystectomized patients with balloon-occludable reinfusion T-tubes were studied during intact and interrupted enterohepatic circulation and four cholecystectomized dogs were studied during interrupted enterohepatic circulation. In man and dog both cholesterol and phospholipid outputs were hyperbolically related to bile salt output by the equation y = x/(a + bx). The output curves intersected the origin and showed an initial rapid rise, followed by a slower increase to a maximum, suggesting a rate-limited mechanism. The shape of the curves permitted calculation of the theoretical maximal outputs and the rates of rise to those outputs. Comparison of these values showed that in both man and dog phospholipid output was greater than cholesterol output and that cholesterol and phospholipid were excreted at different rates. These studies (a) indicate that cholesterol, phospholipids, and bile salts are not excreted in a fixed relationship and (b) demonstrate the usefulness of the derived theoretical maximal lipid output, and the rate of rise of lipid excretion to a maximum, in evaluating the kinetics of biliary lipid excretion.

Adult↗
PubMed1975

Prospective, randomized study of diagnosis and outcome in acute upper-gastrointestinal bleeding: endoscopy versus conventional radiography.

Sixty patients with mild to moderate upper-gastrointestinal bleeding were admitted to a prospective, controlled study of diagnosis and management, and were randomized to endoscopy or upper-gastrointestinal (UGI) barium series as the initial study. Definitive localization of the source of bleeding was made initially in 69% of the endoscopy group and 21% of the UGI group (P less than 0.0005). Of 54 patients undergoing both studies, endoscopy was definitive in 67% and UGI series in 22%. Thus, endoscopy also made more diagnoses when used as the second study (P less than .01). The use of endoscopy as the initial procedure led to significantly more rapid diagnosis than with UGI series. However, there were no significant differences between the two groups in clinical outcome. Endoscopy is the initial diagnostic procedure of choice in patients with mild to moderate upper-gastrointestinal bleeding because it enables detection of superficial bleeding lesions and has significantly increased the speed of diagnosis.

Acute Disease↗
PubMed1975

Pigment vs cholesterol cholelithiasis: clinical and epidemiological aspects.

This prospective study demonstrated that among 92 consecutive patients who underwent cholecystectomy for gallstones at an urban university hospital, 27% had pigment stones and 73% had cholesterol stones. Age, sex, and weight, but not race, were significant determinants of stone type. The mean hemoglobin, direct and total serum bilirubin, and fasting glucose concentrations were similar for each group. The presence of alcoholism, diabetes, thyroid disease, or heterozygous hemoglobinopathy did not influence stone type. The average patient with pigment stones is a lean man or woman 63 years old; in contrast the composite patient with cholesterol stones is a modestly overweight woman 43 years old.

Adult↗
PubMed1975

Effects of meals and interruption of enterohepatic circulation on flow, lipid composition, and cholesterol saturation of bile in man after cholecystectomy.

In 4 patients studied after cholecystectomy and common-duct exploration for cholesterol gallstones, bile salt (BS) and phospholipid (PL) output and bile flow increased significantly in response to breakfast, but cholesterol (Ch) output was unaltered. Simultaneously, Ch concentration decreased while PL and BS concentrations did not change. The degree of Ch saturation of bile, [BS PLUS PL]/[ch], decreased in each study, whether or not the original ratio indicated Ch supersaturation; in 3 of 5 studies, an initially super-saturated bile became unsaturated with Ch in response to breakfast. No significant changes were noted after lunch. During interruption of enterohepatic circulation (EHC), studies with radiolabeled bile acids indicated that the increased bile acid output in response to meals was secondary to increased recirculation of intestinal bile acids rather than to de novo bile acid synthesis. This mechanism may account for the adequate delivery of BS and for the decreased degree of Ch saturation of bile postprandially in cholecystectomized patients.

Aged↗
PubMed1975

Evaluation of radiographic lucency or opaqueness of gallstones as a means of identifying cholesterol or pigment stones. Correlation of lucency or opaqueness with calcium and mineral.

A major criterion for the selection of patients with gallstones for treatment with chenodeoxycholic acid is the radiographic demonstration of lucent gallstones. In this study, we sought to evaluate the degree of selectivity of that criterion for distinguishing patients with cholesterol stones from those with pigment stones and to define the determinants of stone lucency or opaqueness. Of 92 lucent stones, 14% were pigment stones; and of 18 of opaque stones, 33% were cholesterol. Thus, the criterion of stone lucency allows inclusion of a significant number of subjects (14%) with lucent pigment stones, which may account for about one-half of the reported 33% incidence of treatment failures with chenodeoxycholic acid. Conversely, of patients with opaque stones, the one-third with cholesterol stones would be excluded from chenodeoxycholic acid treatment. Calcium is the major metal of both types of stones. However, opaque stones contain 6 times more calcium than lucent stones, which accounts for the difference in radiographic appearance.

Bile Pigments↗
PubMed1973

Triketocholanoic (dehydrocholic) acid. Hepatic metabolism and effect on bile flow and biliary lipid secretion in man.

[24-(14)C]Dehydrocholic acid (triketo-5-beta-cholanoic acid) was synthesized from [24-(14)C]cholic acid, mixed with 200 mg of carrier, and administered intravenously to two patients with indwelling T tubes designed to permit bile sampling without interruption of the enterohepatic circulation. More than 80% of infused radioactivity was excreted rapidly in bile as glycine- and taurine-conjugated bile acids. Radioactive products were identified, after deconjugation, as partially or completely reduced derivatives of dehydrocholic acid. By mass spectrometry, as well as chromatography, the major metabolite (about 70%) was a dihydroxy monoketo bile acid (3alpha,7alpha-dihydroxy-12-keto-5beta-cholanoic acid); a second metabolite (about 20%) was a monohydroxy diketo acid (3alpha-hydroxy-7,12-di-keto-5beta-cholanoic acid); and about 10% of radioactivity was present as cholic acid. Reduction appeared to have been sequential (3 position, then 7 position, and then 12 position) and stereospecific (only alpha epimers were recovered). Bile flow, expressed as the ratio of bile flow to bile acid excretion, was increased after dehydrocholic acid administration. It was speculated that the hydroxy keto metabolites are hydrocholeretics. The proportion of cholesterol to lecithin and bile acids did not change significantly after dehydrocholic acid administration. In vitro studies showed that the hydroxy keto metabolites dispersed lecithin poorly compared to cholate; however, mixtures of cholate and either metabolite had dispersant properties similar to those of cholate alone, provided the ratio of metabolite to cholate remained below a value characteristic for each metabolite. These experiments disclose a new metabolic pathway in man, provide further insight into the hydrocholeresis induced by keto bile acids, and indicate the striking change in pharmacologic and physical properties caused by replacement of hydroxyl by a keto substituent in the bile acid molecule.

Bile↗