Growth Of Monohydrate Crystals Research Articles

The influence of serum and albumin on the constant composition growth and surface properties of calcium oxalate monohydrate

Inhibitor adsorption as a means of reducing crystal growth rates is an area of extreme interest, not only in the prevention of industrial scale formation, but also in the field of biomineralization, especially in urolithiasis research. An investigation of the role of serum and its chief macromolecular component, albumin, in the inhibition of calcium oxalate monohydrate crystal growth in vitro, was carried out by a series of adsorption studies paralleled with constant composition potentiostatic crystallization kinetics reactions. The data indicate albumin as an effective crystallization inhibitor for this system, adsorbing through electrostatic interactions onto the charged crystalline surface.

Growth inhibitor of calcium oxalate monohydrate crystal in vitamin B6-deficient rat urine and kidney.

Urinary and renal inhibitory activities of calcium oxalate monohydrate crystal growth in normal or vitamin B6-deficient rats were investigated. Renal inhibitory activity in vitamin B6-deficient rats was lower than that in normal rats. Renal inhibitory activity in vitamin B6-deficient rats was about 74% of normal level. Urinary inhibitory activity did not show a significant difference between normal and vitamin B6-deficient rats.

The influence of serum and albumin on the constant composition growth and surface properties of calcium oxalate monohydrate

Inhibitor adsorption as a means of reducing crystal growth rates is an area of extreme interest, not only in the prevention of industrial scale formation, but also in the field of biomineralization, especially in urolithiasis research. An investigation of the role of serum and its chief macromolecular component, albumin, in the inhibition of calcium oxalate monohydrate crystal growth in vitro, was carried out by a series of adsorption studies paralleled with constant composition potentiostatic crystallization kinetics reactions. The data indicate albumin as an effective crystallization inhibitor for this system, adsorbing through electrostatic interactions onto the charged crystalline surface.

Surface effects in the crystal growth of calcium oxalate monohydrate

The rates of growth of calcium oxalate monohydrate crystals have been measured under conditions of constant supersaturation over a range of concentrations and in the presence of an inhibitor,N,N,N′,N′-ethylenediaminetetra(methylene phosphonic) acid ENTMP. Changes in the measured specific surface area during the growth reactions are consistent with the observed morphologies of the developing crystals. Well-aged seed crystals undergo a rapid crystal lattice perfection during the initial stages of the reaction which is accompanied by a marked decrease in specific surface area. Initial rates of crystallization are therefore markedly dependent upon the surface properties of the seed crystals. These results emphasize the importance of using well-developed pregrown crystal surfaces in designing experimental studies of the characterization of the mechanism of crystal growth. This is especially important when comparing the influence of adsorbing inhibitor molecules on the crystal growth reactions. The adsorption of ENTMP at the crystal surfaces has been investigated by equilibrium and electrophoretic mobility measurements.

Inhibition of calcium oxalate monohydrate (COM) crystal growth by pyrophosphate, citrate and rat urine.

An assay system for the measurement of the rate of Calcium Oxalate Monohydrate (COM) seed crystal growth in a metastable solution of calcium chloride and sodium oxalate containing traces of 14C-oxalic acid was used to assess the inhibitory activity of pyrophosphate (10(-5) M-10(-4) M), citrate (10(-4) M-10(-3) M) and urines of normal and pyridoxine deficient rats. Both pyrophosphate and citrate were strong inhibitors of COM crystal growth and caused a 50% decrease in crystal growth rate at 1.50 X 10(-5) M and 2.85 X 10(-4) M respectively. Normal rat urine strongly inhibited the COM crystal growth, while pyridoxine deficient animals showed a significant (p less than 0.01) decrease in mean inhibitory activity as compared to pair-fed controls. A lowered urinary inhibitory potential accompanied with hyperoxaluria and hypercalciuria, which is known to be associated with pyridoxine deficiency, may be a contributory risk of calcium oxalate crystallization and stone formation.

Growth of monosodium urate monohydrate crystals: effect of cartilage and synovial fluid components on in vitro growth rates.

The effects of cartilage and synovial fluid components such as proteoglycans, chondroitin sulphate, hyaluronic acid, phospholipids, and albumin on the growth kinetics of monosodium urate monohydrate (MSUM) crystals were investigated. MSUM seed crystals were added to supersaturated sodium urate solutions, and the rate of decrease in the concentration of growth medium was used as a measure of the growth rate. A second order dependence of growth rate on supersaturation was found, and growth rate constants were determined with an integrated form of the growth equation. The additives, hyaluronic acid, proteoglycan monomer and aggregate, and phosphatidylserine, had no significant effect on the growth rate constant. Chondroitin sulphate and phosphatidylcholine increased the growth rate constant, possibly by promoting further nucleation in the growth medium. Albumin significantly inhibited MSUM crystallisation. The possible implications of these findings on in vivo MSUM crystallisation are discussed.

Growth of cholesterol crystals in silica gel

depends on its physical and chemical properties. The growth of crystals of cholesterol in aqueous and other solutions have been reported in the literature [1-3]. The growth of cholesterol monohydrate crystals in supersaturated model bile solution has been studied by Toor et al. [4], but no attempt seems to have been made so far to grow cholesterol crystals by a gel technique. Here we report the growth of these crystals in gels. Sodium silicate solution of certain specific gravity, varying from 1.02 to 1.06 g cm 3, was titrated against glacial acetic acid to prepare the gel [5]. Two different approaches were made. Experiments were done at tropical room temperatures. In the first approach the pH of the titrated solution (sodium silicate + glacial acetic acid) was maintained in the range 4 to 7. Depending on the pH value it took 10 to 30 h for the solution to set. Ethanol was allowed to diffuse into the gel medium by pouring ethanol (95%) on the already formed gel medium. Ethanol was replaced periodically every two days. After 14 days the undiffused ethanol was carefully decanted. Meanwhile, cholesterol solutions in ethanol with concentrations varying from 0.25% to 1% were prepared by dissolving cholesterol (reference standard grade) in 95% ethanol. This was poured carefully over the gel without disturbing the latter. Crystals of cholesterol were found to grow in the course of a week. The growth of crystals was complete within a month. Plate-like crystals were obtained within the gel. A typical crystal obtained by this method is shown in Fig. l a. The crystals were approximately (0.1 x 0.03 cm 2) in dimensions. In the second approach, the pH value of the sodium silicate solution was maintained between 4 and 5. A 2:1 ratio was taken for mixing the sodium silicate solution and the 95% ethanol. It took 10 to 48h for the solution to gel. The solution of cholesterol in 95% ethanol was carefully poured on the top surface of the gel. Nucleations were seen to occur inside the gel. Size of the crystals was almost same as that of the crystals obtained by the first method. Plate-like crystals (Fig. lb) were obtained for pH 5 of the gel and 0.5% concentration of the supernatant cholesterol solution. Crystals were analysed using infrared, differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA). DTA and TGA were carried out on a Dupont 990 Modular Thermal Analysis System (heating rate, 10 ° C min-1 ; atmosphere, nitrogen; flow rate, 50 cm 3 min-~; sample weight, 2 to 5 mg). Both of the thermoanalytical methods, namely, DTA and TGA, clearly indicated that the crystals were hydrated. The thermograms are reproduced in Fig. 2a and b. The DTA showed an endothermic peak at about 80°C which is characteristic of the monohydrate cholesterol. The rate of growth of the crystals was slow from the beginning. During the process of diffusion of cholesterol through the gel, ethanol does not react in any way with the gel, but the cholesterol becomes supersaturated. This leads to the nucleation of cholesterol crystals and, subsequently, to the growth and development of the nucleated crystal.

Purification and characterization of the principal inhibitor of calcium oxalate monohydrate crystal growth in human urine.

Using an assay of the rate of crystal growth of calcium [14C]oxalate monohydrate, we ascertained that the factor responsible for more than 90% of the crystal growth inhibition in human urine is a nondialyzable macromolecule. We have purified this factor using DEAE-cellulose chromatography, followed by Bio-Gel P-10 column chromatography with 50% formamide as the eluent, and finally by gel permeation chromatography. About 5 mg of the inhibitor was obtained from normal 24-h adult urine, with 16% recovery of the original inhibitory activity. The inhibitor isolated was found to be a highly acidic glycoprotein with Mr = 1.4 X 10(4). It is rich in acidic amino acids, including gamma-carboxyglutamic acid, and contains few aromatic and basic amino acids. Two or three phosphate groups are covalently linked to the inhibitor. In the presence of the inhibitor, the kinetics of calcium oxalate monohydrate crystal growth inhibitor showed that the macromolecule binds to the crystal surface according to a Langmuir adsorption isotherm with a dissociation constant, Kd = 5.3 X 10(-7) M. The inhibitor readily formed an insoluble monolayer at the air-water interface and showed an unusually high surface stability with a collapse pressure of 41.5 dynes/cm. The urinary inhibitor closely resembled in all properties the calcium oxalate monohydrate crystal growth inhibitor that we had isolated from human embryonic kidney tissue culture medium (Nakagawa, Y., Margolis, H. C., Yokoyama, S., Kézdy, F. J., Kaiser, E. T., and Coe, F. L. (1981) J. Biol. Chem. 256, 3936-3944).

Inhibition of chondroitin sulphate and heparin on the growth and agglomeration of calcium oxalate monohydrate crystals in vitro

Seed experiments on the growth of calcium oxalate monohydrate in vitro have given the following results. Chondroitin sulphate does not influence the growth but only the agglomeration. The main influence of heparin at all concentrations is to inhibit the agglomeration, but at concentrations greater than about 10 −8 mol/l the growth is also inhibited. In the range 0.05–30 μmol/l there is a linear dependence between the percentage inhibition of the growth and the concentration of heparin.

The Influence of Polyphosphate Ions on the Precipitation of Calcium Oxalate

We studied the growth of calcium oxalate monohydrate (COM) crystals in stirred suspensions by following the changes in ionic conductivity of supersaturated solutions at 25 ± 0.02C. At a pH of 6.9–7.2, in the presence of polyphosphate ion, crystallization proceeded by an initial rapid step followed by a markedly reduced growth rate as compared with that in pure supersaturated solution. The initial surge was reduced as the polyphosphate concentration reached 1.6 × 10–6 M, which can be interpreted as evidence of either surface nucleation or the incomplete adsorption of inhibitor at the active growth sites. In spontaneous precipitation experiments made in the presence of polyphosphate ions, the formation of calcium oxalate dihydrate and trihydrate is favored together with appreciable coprecipitation of additive ions.

Urinary crystal growth: effect of inhibitor mixtures.

1. The crystal growth inhibitory activity of mixtures of known inhibitors and of mixtures of known inhibitors with normal urine was determined in calcium oxalate monohydrate and hydroxyapatite seeded crystal growth systems. 2. The inhibitory activity of the mixtures was compared with the measured activity of the individual components of the mixtures. All mixtures had inhibitory activity equal to the sum of the activities of their components, with the exception of RNA/urine mixtures in the calcium oxalate monohydrate system. 3. RNA/urine mixtures had inhibitory activity toward calcium oxalate monohydrate crystal growth which was less than would be predicted from the activity of the RNA and of the urine which were added. This reduced inhibitory activity was shown to be due probably to hydrolysis of RNA by the ribonuclease activity normally present in urine. 4. The results of these experiments make it possible to determine quantitatively the contribution of various naturally occurring urinary crystal growth inhibitors to the total measured inhibition observed in urine.

Purification and characterization of a calcium oxalate monohydrate crystal growth inhibitor from human kidney tissue culture medium.

Purification and characterization of a calcium oxalate monohydrate crystal growth inhibitor from human kidney tissue culture medium.

Epitaxial relationships in urolithiasis: the calcium oxalate monohydrate-hydroxyapatite system.

Chemical kinetic data, complemented with scanning electron-microscope observations of the crystalline phase, show that seed crystals of hydroxyapatite have the ability to induce the growth of calcium oxalate monohydrate crystals epitaxially from a metastable supersaturated solution of calcium oxalate. The rate of growth of calcium oxalate crystals is dependent on the surface area of the seed material and follows a second-order rate law. It is suggested that there may be a causal relationship between the occurrence of apatite crystals in the urinary tract and the formation of both 'pure' and mixed urinary stones containing calcium oxalate. Under similar experimental conditions, however, seed crystals of calcium oxalate monohydrate appeared unable to induce epitaxially the growth of calcium phosphate crystals from a supersaturated calcium phosphate solution, indicating the absence of an epitaxial relationship between calcium oxalate monohydrate and the initially precipitating calcium phosphate phase(s).

Kinetics of crystal growth of calcium oxalate monohydrate

The growth of calcium oxalate monohydrate crystals in stirred suspensions has been studied by following the changes in ionic conductivity in supersaturated solutions containing both stoichiometric and non- stoichiometric concentrations of lattice ions at various temperatures in the range 15–45 °C. The reaction can be represented in all cases by a kinetic equation which involves a quadratic dependence of the rate of crystallization upon the relative supersaturation. This points to a process in which the crystal growth is controlled by a reaction at the crystal surface rather than by diffusion of lattice ions in the bulk solution. The effect of several inorganic phosphates, polyelectrolytes and organic dyes on the growth kinetics has been studied and the heat of solution of calcium oxalate, determined by a direct calorimetric method, 5.33 kcal mole -1, may be compared with the value, 5.5 kcal mole -1, calculated from the temperature coefficient of the solubility product. The thermodynamic association constant for the 1:1 calcium oxalate complex at 25 °C, determined by the conductimetric method, is 1537 1 mole -1 and there is no evidence for higher order species under the conditions of the crystallization experiments. The kinetic results are discussed in terms of the important problems relating to the origin and growth of urinary calculi.