Calculation of titratable acidity from urinary stone risk factors.

Using urine samples and standard solutions, this study demonstrates that the existing procedure for measuring titratable acidity in the urine is not reliable and may result in overestimates of up to 25%. The accuracy is affected by loss of CO2, the presence of uric acid crystals, and the precipitation of calciumphosphate phases during the titration. A method is presented for calculating titratable acidity, using a number of routinely-measured urine components and a computer program for calculating complex equilibria in the urine.

Physicochemical considerations in the development and prevention of calcium oxalate urolithiasis.

Calcium oxalate urolithiasis is very common in western societies. In recent years significant progress has been made in identifying and quantitating physico-chemical processes involved in calcium oxalate urinary stone formation. The ability of urine to inhibit the agglomeration of calcium oxalate crystals is an important protective mechanism against stone formation.

Diagnosis of liver tapeworm, Stilesia hepatica, infection in sheep.

A practical method of diagnosing Stilesia hepatica in live sheep is described. Intestinal contents and faeces were sieved through a sieve with apertures of 1.0 mm onto a sieve with apertures of 100 microns to reduce volume and turbidity.

The effects of dietary excesses in animal protein and in sodium on the composition and the crystallization kinetics of calcium oxalate monohydrate in urines of healthy men.

Dietary excesses in animal protein and/or salt have been implicated as risk factors in calcium oxalate urolithiasis. The underlying physicochemical mechanism is, however, not known. Eight healthy men were given four different diets varying in animal protein and in sodium content for 1 week each.

Crystal agglomeration is a major element in calcium oxalate urinary stone formation.

The effects of urines from 36 healthy subjects and 86 calcium oxalate renal stone formers on calcium oxalate monohydrate crystallization kinetics were studied using a seeded crystal growth method in which the solubility, the growth and the agglomeration of the crystals are measured as three separate and system-independent parameters. The urines of healthy subjects were found to increase the solubility and to strongly inhibit the growth and the agglomeration of calcium oxalate monohydrate crystals. The urines of stone formers had a similar effect on the solubility, but a significantly lower ability to inhibit the crystal growth and the crystal agglomeration.

Modulation of calcium oxalate monohydrate crystallization kinetics in vitro.

The effects of several low and high molecular weight (mol wt) compounds on the kinetics of calcium oxalate crystallization were examined using a seeded crystal growth method in which the solubility, the growth and the agglomeration of calcium oxalate crystals were measured as three separate and system-independent parameters. Citrate, magnesium, phosphate, pyrophosphate, chondroitinsulphate, pentosanpolysulphate and heparin were tested in a wide range of concentrations. The solubility of calcium oxalate crystals was increased only by citrate and magnesium.

Polysaccharide from coccoliths (CaCO3 biomineral). Influence on crystallization of calcium oxalate monohydrate.

A polysaccharide associated with coccoliths of the marine alga Emiliania huxleyi (coccoliths are elaborately shaped calcite biominerals) was isolated and its influence on the crystallization of calcium oxalate monohydrate crystals was studied. Crystallization was monitored in a carefully controlled system by measuring the incorporation of 45Ca tracer from a supersaturated solution into seed crystals of calcium oxalate monohydrate in the absence and in the presence of polysaccharide. The method allowed differentiation between effects on solubility, growth and agglomeration of crystals.

Excessive crystal agglomeration with low citrate excretion in recurrent stone-formers.

In 7 highly recurrent calcium oxalate stone-formers and 10 healthy subjects the effects of urine on three processes of calcium oxalate monohydrate crystallisation--solubility, crystal growth, and crystal agglomeration--were studied. The urine of the stone-formers showed low calcium oxalate solubility and normal crystal growth inhibition, but lacked the ability to inhibit crystal agglomeration. As the sole metabolic abnormality, all stone-formers showed hypocitraturia.

Regulation of the C3 nephritic factor stabilized C3/C5 convertase of complement by purified human erythrocyte C3b receptor.

Activation of complement may result in the generation of the amplification convertase C3bBb. This convertase can be stabilized by properdin (P) or C3NeF. C3bBbP is susceptible to inactivation by beta 1H, while C3bBbNeF is relatively resistant.

DETERMINATION OF THE SERUM IRON-BINDING CAPACITY.

A colorimetric and an isotopic method for determining the iron-binding capacity are described, using only 1 ml. samples of plasma or serum. Both methods are simple, rapid and sensitive.

FOUR CASES OF WALDENSTROEM'S MACROGLOBULINAEMIA.

The clinical course and pathological features of four cases of Waldenström's macroglobulinaemia are described. One was associated with a localized carcinoma of the bronchus and one with a chromophobe adenoma of the pituitary. Trypsin digest preparations of the retina were examined in two cases, one with severe retinopathy and the other with no clinical evidence of ocular disease, and the findings are briefly described.

Serum iron determination.

A simple, rapid, and sensitive method for the determination of iron in serum or plasma is described. The procedure is carried out at room temperature with 2 ml. of serum or plasma, or with 1 ml.