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Biomedical subjects

W Achilles

Publications and source records attributed to W Achilles.

9 recordsLinked to original sources
PubMed1991

Crystal growth of calcium oxalate in urine of stone-formers and normal controls.

In this study, the relative crystal growth rate (Vcr) of calcium oxalate (Caox) and a number of other parameters were determined in 17-h daily (d) and 7-h nocturnal fractions (n) of whole urine from 20 recurrent Caox stone formers (SF) and 29 age-matched male normal controls (NC). Vcr, which was determined by the gel crystallization method (GCM), showed the largest difference between SF and NC among all parameters under investigation. Mean values (+/- SD) obtained for Vcr were: 0.73 +/- 0.58 (SF-d)/0.21 +/- 0.22 (NC-d; P less than 0.001) and 0.63+/- 0.58 (SF-n)/0.24 +/- 0.25 (NC-n; P less than 0.01). Significantly higher concentrations of Ca and lower concentrations of thermodynamic and kinetic effectors of Caox crystal growth were responsible for the higher crystal growth rates observed in SF as compared with NC, i.e., they should be partially causative in Caox urolithiasis. However, other properties of urine or the urinary tract (potentially, crystal agglomeration and adhesion) must be accounted for in the genesis of Caox stones.

Adult↗
PubMed1990

The in-vivo effect of sodium-potassium citrate on the crystal growth rate of calcium oxalate and other parameters in human urine.

In this study, an efficient microtechnique (gel crystallization method) was used to investigate the in-vivo effect of sodium-potassium citrate on the crystal growth rate of calcium oxalate (Vcr) in human urine samples of 6 healthy volunteers. With a daily dose of 3 X 11 mmol of alkali citrate, Vcr decreased by 70%. This could have been due to the decrease of calcium excretion, which caused 50-60% of the total change, and to the increase of citrate and pH, each contributing about 20-25% to the decline of Vcr. The findings explain the clinical advantages of alkali citrates in the prevention of recurrent calcium oxalate stone formation.

Adult↗
PubMed1978

[Determination of the concentration of free magnesium ions in hemolysates of oxygenated and deoxygenated packed human erythrocytes].

Concentrations of ionized magnesium in hemolyzates of oxygenated and deoxygenated human erythrocytes were measured directly by means of an ion exchange method. At total concentrations of hemoglobin of 8 mmol/l H2O and total magnesium of 3.6 mmol/l H2O, mean values of [Mg2+] were found to be 0.45 in the oxygenated state and 0.57 mmol/l H2O in the deoxygenated state. The difference of 0.12 +/- 0.1 mmol/l H2O is considerably smaller than corresponding literature data obtained from equilibrium calculation.

Erythrocytes↗
PubMed1977

[An ion exchange method to determine free metal concentrations, adapted for use in biological fluids: methods and determination of (Mg2+)].

An ion exchange method for measuring concentrations of free (ionized) metal ions and its application to the determination of [Mg2+] is described. A surface sulfonated polystyrene material is used as the "twodimensional" cation exchanger. The sample-volume is 1 ml. About 50 determinations can be performed within 1 hr having a standard error of +/- (2-4)% in the optimal range of measurement. Advantages and disadvantages of the method compared with other ones are demonstrated and discussed. Free Mg2+ ion concentrations were measured in solutions containing pyrophosphate as well as haemoglobin and compared with those which were determined by equilibrium calculation or ultrafiltration.

Cation Exchange Resins↗