Biomedical subjects
Publications and source records attributed to B Finlayson.
A survey of 1974 discharge data from United States hospitals shows an apparent increase in urolithiasis. A negative correlation has been found between the geographical distribution of the relative frequency of hospital discharges, a diagnosis of urolithiasis, and reported water hardness.
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A case of bilateral hydronephrosis after transureteroureterostomy is reported. Management of such complications may be difficult and should include innovative ureteral salvage based upon fundamental principles of ureteral surgery.
The early phases of calcium oxalate crystal formation in rat kidneys after intraperitoneal challenge with sodium oxalate were examined. From the results we conclude that the crystals are formed intraluminally in the proximal tubules of the renal cortex. The size, number, and distribution of calcium oxalate particles depend on the amount of sodium oxalate injected and the time interval after its injection. Tubular necrosis and dilation were evident after administration of higher doses of sodium oxalate. The papillary tip and corticomedullary junction were the preferential sites for crystal localization after longer periods of injections of higher doses of sodium oxalate.
Solubility measurements, seeded crystal growth kinetics, solution depletion adsorption studies, nucleation observations, zeta potential measurements, and measurements of in vivo intrarenal crystallization all failed to show that either oxipurinol or allopurinol riboside interacts with calcium, oxalate, or whewellite (CaC2O4.H2O) at concentrations expected in therapeutic situations. We conclude that at therapeutically expected concentrations, oxipurinol and allopurinol riboside do not affect crystallization of calcium oxalate.
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The adsorption of heparin on sodium acid urate powder suspended in aqueous solution was found to be dependent upon the concentration of Ca2+ and Mg2+. It was concluded that heparin adsoprtion on sodium acid urate powder can occur in urine. Speculations are made about the relevance of these observations to calcium oxalate urolithiasis.
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The adsorption of pyrophosphate and citrate to whewellite was measured by solution depletion. At pH 6.5, the concentration for one-half surface coverage CE(1/2) by pyrophosphate is 15 micrometer. The estimated maximum coverage is 37.5 mumoles per m2. The CE (1/2) for citrate is 4 micrometer, and the estimated maximum coverage is 6.42 mumoles per m2.
In an effort to rationalize the difference between computed estimates of urinary calcium oxalate supersaturation and estimates obtained by equilibrating urine with solid calcium oxalate, we examined ultrasfiltered urine for the binding of urinary ions. Urine was passed through a filter with a nominal passage cutoff of 1000 Daltons. The average reduction in concentration of the ultrafiltrate was 12.7 per cent for oxalate, 11.9 per cent for phosphate, 9.4 percent for calcium, 7.6 per cent for magnesium, and 6.9 per cent for sodium. From these results we conclude that calculations of urinary ion equilibrium will give better estimates if the composition of ultrafiltered urine is used.
In an effort to evaluate the rate of stone disease, a questionnaire was sent to each hospital in the United States. On the basis of 1765 responses it is estimated that the average rate of hospital discharge diagnoses of urinary stone per all hospital discharges was 0.0102. It was calculated that the annual incidence of urolithiasis in the population is at least 16.41 per 10,000 and that approximately 12 per cent of the population is expected to have urinary stone disease at some time in their lives.
There is a paucity of literature concerning the origin of urinary stone disease. This report uses information currently available to examine the likelihood of urinary stone disease starting from free or fixed crystalluric particles. We conclude that stone disease in the renal tubules and renal pelvis cannot begin on unattached (free) particles. However, in conditions associated with stone formation, initiation of bladder stone disease on free particles seems quite likely.
This paper examines the kinetics of calcium deposition in rat kidneys after an intraperitoneal sodium oxalate injection. From the results we conclude that only a limited portion of tubular surface is available for adsorption of calcium oxalate crystals, that adsorpption of calcium oxalate crystals onto tubular epithelium is a process of greater than first order with regard to the dose, and that the washout of retained particles from the tubules is a first-order process as related to time. Also, we conclude that in these animals, which were subjected to a large oxalate challenge, the deposition of calcium oxalate crystals is virtually all intratubular.
On the basis of measurements of adsorption, solution depletion, zeta potential, solubility, seeded-crystal growth, nucleation, and intrarenal precipitation in rats, it was not possible to show that allopurinol retards the crystallization of calcium oxalate (whewellite).
A single intraperitoneal injection of sodium oxalate was used to induce intrarenal tubular precipitation of calcium oxalate in rats. This experimental model was used to screen the efficacy of hydrochlorothiazide, orthophosphate, methylene blue, trypan blue, retinal folic acid, neuraminidase, and lysozyme in retarding intratubular calcium oxalate precipitation. Orthophosphate caused a 53 per cent reduction in calcium oxalate precipitation relative to the control animals.
The adsorption of proteins and mucopolysaccharides on calcium oxalate crystals was measured by solution depletion. Anionic protein adsorption was found to be sensitive to calcium ion concentration. Adsorption of fibrinogen was anomalously large in the presence of 0.01 M Ca2+. Adsorption of cationic protein (histone) was sensitive to oxalate ion concentration. A small alteration in adsorption of protein as a result of pH or temperature change was also observed. Plots of adsorption versus concentration were interpreted in terms of a Langmuir adsorption isotherm. The derived Langmuir adsorption parameters were then used to investigate the contribution of protein, by physical adsorpti, to the quantity of matrix in urinary stones. It was concluded that physical adsorption can account for the deposition of part but not all of the matrix in calcium oxalate stones. It was also concluded that physical adsorption of mucopolysaccharides by calcium oxalate crystals could explain the inhibition of growth and aggregation of calcium oxalate crystals seen with in vitro precipitation systems. Recalculation of published data indicates that adsorption of protein on dental enamel (calcium hydroxyapatite) results in approximately the same extent of surface coverage as adsorption on calcium oxalate crystals, but protein has a much lower affinity for dental enamel than for calcium oxalate crystals.
An animal experimental model was used to study oxalate absorption from the gut. It was found that the initial rate of [14C]oxalate absorption is rapid (6.5 per cent per min), and that after 5 min the rate of absorption decreases to about 0.6 per cent per min. Absorption of [14C]oxalate was greatest in the jejunum and least in the colon. On the basis of linear coefficients derived from the data, it is estimated that at least 8.6 per cent of a challenge dose of oxalate should be absorbed from the small bowel during normal transit. The high absorption rate, compared with the normal absorption of oxalate, in this model is most likely attributable to the oxalate's being completely dissolved in the gut. Magnesium and calcium in the test solution did not cause large changes in the rate or amount of oxalate transfer in this experimental model.