D. June Sutor

Calcium in bile and calcium salts in gallstones.

In gallbladder and common duct bile from patients undergoing cholecystectomy, usually because of gallstones, calcium was found to exist in at least 2 forms. Ultrafiltration showed some calcium was bound to substances with a molecular weight greater than 10 000, and the chief binding agent is likely to be the mixed micelle. Bound calcium was significantly less in common duct bile than in bile from functioning gallbladders, but the amount of ultrafiltrable calcium was the same. Furthermore, ultrafiltrable calcium in gallbladder bile from patients with cholesterol or some calcium carbonate in their gallstones was almost constant for a range of total calcium concentrations of 2.40--9.70 mmol/l. Comparison of ultrafiltrable and total calcium values for the different types of stone-formers showed that the deposition of calcium carbonate in gallstones was not related to any calcium measurement made. However, the presence of calcium phosphate and/or calcium bilirubinate in gallstones could be related to a significant increase in ultrafiltrable calcium in gallbladder bile.

Uric acid dihydrate in bird urine.

X-ray diffraction analysis shows that the white excrement from a budgerigar, consists mainly of uric acid dihydrate. Initially this material is in the form of a smectic (or cholesteric) phase, which transforms to the normal crystalline phase either on aging or on removal of the minor (soluble) constituents of the excrement with water or dilute acids.

Gallstone of Unusual Composition: Calcite, Aragonite, and Vaterite

A gallstone of almost perfect octahedral symmetry was composed of a mixture of crystallites of the three polymorphous forms of calcium carbonate: calcite, aragonite, and vaterite.

The effect of bile on the crystallisation of calcium carbonate, a constituent of gallstones

When calcium and bicarbonate ions were mixed at room temperature (approximately 20 degrees C) to give concentrations of 4 mmol/1 and 21 mmol/1 respectively and the pH of the solution was kept at 8.3, vaterite, a form of calcium carbonate, was precipitated almost immediately as spheres of diameter 45 micron. The crystallisation of this material could be slowed down by adding to the crystallising medium small amounts of pyrophosphate or citrate which often inhibit crystal growth. High concentrations of sodium chloride (90 mmol/1) did not, however, affect the reaction. Very small amounts of gallbladder bile from patients with only cholesterol on the surface of their gallstones inhibited the crystallisation of calcium carbonate, and the size of the spheres was only 0.37 times those produced in water. The activity of the bile could be attributed to material with a molecular weight greater than 10 000. On the other hand, bile from patients having some calcium carbonate on the gallstone surface had less activity than comparable amounts of bile from patients with only cholesterol in this area. The active material may, therefore, play a part in preventing the deposition of calcium carbonate in gallstones.

Isolation and identification of some urinary inhibitors of calcium phosphate formation.

Normal urine has been examined for substances which inhibit formation of calcium phosphate. A separation scheme involving ultrafiltration, precipitation, electrophoresis and paper chromatography was devised to isolate these substances. Contrary to what has been suggested in the literature for many years, the urines examined did not contain a potent unidentified inhibitor. The major anionic inhibitors were citric acid, pyrophosphate and isocitric acid. These substances together with a small contribution from the cations appeared to account for most, if not all, of the inhibitory activity of urine.

Inorganic phosphorus in human bile

The inorganic phosphorus concentration has been measured in fresh bile from patients undergoing cholecystectomy, usually because of cholelithiasis. The amount in common duct bile for patients with cholesterol on the stone surface was significantly higher than that for patients with some calcium carbonate in this area. For all patients with functioning gallbladders, inorganic phosphorus in gallbladder bile was always higher than that in the corresponding common duct bile. In bile from functioning gallbladders, inorganic phosphorus was linearly related to pH for cholesterol stone-formers, but values for calcium carbonate stone-formers were below the regression line and not related to pH. The results show that bile from calcium carbonate stone-formers is more dilute with respect to inorganic phosphorus.

The estimation of D-isocitric acid in urine using isocitrate dehydrogenase.

The amount of D-isocitric acid in urine has been estimated using the enzyme isocitrate dehydrogenase. The technique is rapid and easy to perform. Reproducibility of results was good and results from recovery experiments were excellent. The concentration range for early morning urine samples from normal adults was 0.08-0.65 mmol/l with a mean of 0.29 mmol/l.

An assay method for the measurement of urinary inhibitors of calcium phosphate formation.

An assay method has been developed for studying quantitatively the formation of calcium phosphate. The method will detect both substances which affect the solubility of calcium phosphate and substances which affect the crystal growth of the material. It is sensitive as or more sensitive than other methods described in the literature for detecting such compounds.

Crystal growth in bile

Abstract Crystal growth frequently occurs in bile, resulting usually in the formation of gallstones. From patient to patient, these vary in number, size, colour and shape, as well as in composition. Cholesterol is the most common constituent, but certain calcium salts, notably calcium carbonate, are frequently present. Factors which can contribute to the crystallisation of bile are discussed, together with those resulting in the transferrence of tiny nuclei into the complex structures of gallstones. Some of these may be crystal aggregation, overgrowth and epitaxy which may or may not take part in a gel which is the matrix of gallstones.

Phase changes during heating of magnesium ammonium phosphate hexahydrate and magnesium hydrogen phosphate trihydrate to high temperatures

Magnesium ammonium phosphate hexahydrate MgNH4PO4,6H2O and magnesium hydrogen phosphate trihydrate MgHPO4,3H2O have been heated to temperatures up to 1220° and X-ray powder photographs taken of the products. Both substances decompose during the process and gradually change first into an amorphous phase and then into crystalline magnesium pyrophosphate. The incandescence which appears on the ignition of these substances may be associated with the dimerisation of the ion HPO42–.