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R D Soloway

Publications and source records attributed to R D Soloway.

82 records · Page 5Linked to original sources
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Water content of gallstones: location and contribution to a hypothesis concerning stone structure.

The water content of black pigment and cholesterol gallstones was evaluated with the use of moisture evolution analysis, electron spectroscopy for surface analysis, and X-ray diffraction. X-ray diffraction identified complex hydrated hydroxyapatite compounds in two stones. Moisture evolution analysis demonstrated that 18 pigment gallstones contained between 0.83 and 6.87% water; six cholesterol stones contained 0 to 0.27% (p less than 0.001). When black stones were subdivided into subgroups containing large proportions of pigment, phosphate, or carbonate, the proportion of water evolved at each temperature was the same. Water content was inversely related to carbonate content (r = -0.81) and did not correlate well with other stone components. Electron spectroscopy for surface analysis independently suggested that water of hydration was present since the ratio of oxygen to other elements exceeded ratios in any known compound in stone. A peripheral-central gradient for water was absent in one stone which was analyzed in peripheral mid-, and central portions. Progressive removal of the surface of previously ground stone particles using an argon beam followed by repeated electron spectroscopy for surface analysis indicated that much of the water was present in the outer 20 to 50 A of the particles. The data are consistent with the hypothesis that pigment stones form by deposition of calcium salts on an organic matrix and that hydrated water is associated with thin layers of calcium salts. These layers may be distributed throughout the stone; powdering appears to fractionate stones through these areas of hydrated calcium salts since oxygen was in highest concentration on the surface of powder particles.

Bilirubin↗
PubMedDate not supplied

Pigment gallstone disease: Summary of the National Institutes of Health--international workshop.

This report summarizes the proceedings of the first National Institutes of Health--International Workshop on Pigment Gallstone Disease. The meeting held at the University of Pennsylvania in May, 1981 consisted of eight sessions in which the following aspects of pigment gallstone disease were discussed: (a) classification; (b) epidemiology; (c) radiographic assessment; (d) gallstone composition; (e) composition of bile; (f) pathogenesis; (g) animal models, genetics, and computer analysis, and (h) medical treatment. The interaction of participants interested in various aspects of pigment stone disease was stimulating. This workshop should be a major stimulus for future studies in this relatively neglected, but important area of biliary tract lithiasis.

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PubMedDate not supplied

Mucin glycoprotein content of human pigment gallstones.

Mucin glycoproteins, a secretory product of the gallbladder, are thought to contribute to the matrix or nucleus of gallstones. Human black pigment stones originate in the gallbladder and have as their major constituent calcium bilirubinate, as well as inorganic salts and small amounts of cholesterol. The object of this study was to estimate the amount of glycoprotein in black pigment stones and to isolate gallbladder mucin from dissolved stones. Black pigment stones containing 18 to 65% calcium bilirubinate were first dissolved in 12.5 mM EDTA/0.1 N NaOH and decolorized, then subjected to glycoprotein assay. The mean glycoprotein content of eight stones was 12.4%. In separate experiments, pigment stones were partially dissolved by brief exposure to EDTA/NaOH to minimize glycoprotein breakdown, and the glycoproteins isolated by gel filtration and ultracentrifugation. Pigment stones contained two glycoprotein fractions on Sepharose 4B; a high molecular weight mucin glycoprotein in the void volume and a lower molecular fraction in the included volume. Mucin was further purified by density gradient ultracentrifugation in cesium chloride. Three separate mucin fractions had an average buoyant density of 1.48 gm per ml which is typical for these glycoproteins. Bile pigment was associated with high molecular weight mucin even after extensive dialysis, gel filtration, and density gradient ultracentrifugation. The identity of mucin was further established by beta-elimination of glycoproteins in alkaline borohydride which yielded galactosaminitol from cleavage of O-glycosidic bonds. Our results indicate that mucin glycoproteins are present in significant concentrations in human black pigment stones and can be purified from stones solubilized in EDTA/NaOH. The association of bile pigment with gallbladder mucin, even after extensive purification, is consistent with the hypothesis that mucin contributes to the matrix of pigment gallstones.

Bilirubin↗
PubMedDate not supplied

Black and brown pigment gallstones differ in microstructure and microcomposition.

The two subtypes of pigment gallstones, black and brown stones, differ in chemical composition and pathogenesis. We examined a black bilirubinate stone and a black phosphate stone (which represented opposite ends of the compositional spectrum of black noncarbonate stones), a black carbonate stone, and a brown pigment stone using scanning electron microscopy and microchemical techniques to determine if stone microstructure and microcomposition reflected different patterns of formation. The cross-sectional surfaces of the black bilirubinate and black phosphate stones were smooth and homogenous. Electron probe microanalysis demonstrated high concentrations of sulfur and copper in the center of the black bilirubinate stone; sulfur was in a low valence state consistent with disulfide linkages in proteins. The brown stone was rough-surfaced with lamellated bands on cross-section. The lighter-colored bands in this stone contained virtually all of the detected calcium palmitate, while the darker sections contained much more calcium bilirubinate. Plasma oxygen etching demonstrated a network of protein interdigitating with calcium bilirubinate salts in the black bilirubinate and black phosphate stones but not in the black carbonate or brown stones. Argon ion etching demonstrated that calcium bilirubinate was in a closely packed rod-shaped arrangement in all three black stones but not in the brown stone. We conclude that the marked differences in structure and composition between the black noncarbonate and brown pigment gallstones support the hypothesis that the two major pigment gallstone types form by different mechanisms. In addition, the layered structures of the black carbonate and brown stones suggest that stone growth is affected by cyclic changes in biliary composition.

Argon↗
PubMedDate not supplied

Composition of pigmented centers of cholesterol gallstones.

Most cholesterol gallstones have visually pigmented centers, but it is unclear whether this represents simple co-precipitation of pigment with cholesterol during stone nidation or nidation on a true pigment stone center. To clarify this issue, we selected from among 67 sets of cholesterol gallstones, 12 sets with the most conspicuously pigmented centers. The composition of the centers and the peripheries of these 12 stones was analyzed using infrared spectroscopy and compared with that of 10 black pigment gallstones. The pigmented centers of cholesterol stones contained 80.1 +/- 7.9% (mean +/- S.E.) cholesterol, 6.2 +/- 3.4% calcium bilirubinate (only 4 of the 12 centers had measurable calcium bilirubinate), trace amounts of calcium phosphate and no calcium carbonate or calcium palmitate. The peripheral areas of the cholesterol stones contained 91.6 +/- 2.3% cholesterol and no detectable calcium salts. For comparison, the composition of the centers of 10 black pigment gallstones was 13.5 +/- 2.2% cholesterol, 28.2 +/- 5.3% calcium bilirubinate, 5.5 +/- 2.4% calcium phosphate and 10.6 +/- 5.8% calcium carbonate. The composition of only one cholesterol stone center (15.8% cholesterol, 26.8% calcium bilirubinate) resembled that of a pigment stone, but even this center differed from that of a typical pigment stone in that it contained only a trace amount of calcium phosphate and no calcium carbonate. Thus, the chemical composition of pigmented centers of cholesterol gallstones is quantitatively different from that of black pigment stones, suggesting that cholesterol gallstones do not form on a pigment stone nidus.

Bilirubin↗
PubMedDate not supplied

The calcium ionophore A23187 stimulates glycoprotein secretion by the guinea pig gallbladder.

The purpose of this study was to examine the role of calcium ions in gallbladder glycoprotein secretion in cultured guinea pig gallbladder explants. The calcium ionophore A23187 showed a threshold of 2 micrograms per ml medium for stimulation of secretion of [3H]glucosamine-labeled glycoproteins over a 30 min incubation period. The ionophore at 3 and 5 micrograms per ml medium resulted in a 3- to 4-fold increase in secretion of [3H]glucosamine-labeled glycoproteins. Ionophore-induced stimulation of glycoprotein secretion was abolished by the addition of 0.01 mM verapamil to the medium. To study the effect of changes in extracellular calcium on basal glycoprotein secretion, explants were cultured for 24 hr in media with 0.007, 0.5 or 2.0 mM calcium; no differences in basal glycoprotein secretion were observed. When cultured in medium with 1.0 mM EGTA, basal secretion decreased significantly vs. controls in 0.007 mM total calcium medium. Total [3H]glucosamine incorporation by explants in medium with EGTA was unaltered, however, suggesting that the low level of calcium in the medium was selectively impairing the secretory process. These findings indicate that calcium ions are important in the regulation of gallbladder glycoprotein secretion.

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