Urinary & serum oxalate determination by oxalate oxidase immobilized on to affixed arylamine glass beads.

BACKGROUND & OBJECTIVE: Although the measurement of oxalate in urine and serum by Amaranthus leaf oxalate oxidase immobilized on free arylamine glass beads is highly sensitive and specific, the handling of glass beads is tedious and cumbersome. The present study was undertaken to overcome this problem. METHODS: Partially purified Amaranthus spinosus leaf oxalate oxidase was immobilized through diazotization onto arylamine glass beads affixed on the surface of a plastic strip by a non reactive fixative and employed for oxalate determination in urine and serum samples collected from healthy individuals and urinary stone formers. RESULTS: The immobilized enzyme retained 56 per cent of its initial activity with a conjugation yield of 40 mg/g support. The strip bound enzyme showed maximum activity at pH 3.5 when incubated at 40 degrees C for 15 min. The minimum detection limit of the method was 0.01 mM/l in the urine and 2.5 microM/l in the serum. The analytical recovery of added oxalate was 97.7+/-1.2 per cent in urine and 92.0+/-2.4 per cent in serum. Within and between assay coefficient of variation (CV) were 4.6 and 5.2 per cent in urine and 7.4 and 5.8 per cent in serum respectively. A good correlation for oxalate in urine (r1= 0.99) and in serum (r2= 0.92) was obtained between Sigma kit method and the present method. The strip could be reused 150 times over a period of 2 months, when stored at 4 degrees C in reaction buffer. INTERPRETATION & CONCLUSION: Immobilization of Amaranthus leaf oxalate oxidase on to affixed glass beads provided enormous ease in its reuse for determination of oxalate in urinary and serum samples.

Evaluation of free amino acids in plasma and 24 - hour urine samples of control subjects and patients with calcium urolithiasis

To evaluate free amino acid levels in Plasma and 24-h urine samples of control subjects and patients with calcium urolithiasis. Design: Amino acid analysis of Plasma and 24-hour urine samples. Setting: Department of surgery, Combined Military Hospital, Hyderabad and Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro. Subject All calcium stone formers and controls are hospital in-patients. Main outcome measures: To demonstrate differences between calcium stone formers and non-stone forming controls with respect to their plasma and 24-hour urine amino acid profiles. Plasma levels of aspartic acid, glutamic acid, glycine, histidine, hydroxyproline, isoleucine, leucine, methionine, phenylalanine, proline, serine, threonine, tyrosine and valine were significantly higher [p <0.01] in calcium stone patients than in control subjects. The urinary excretions of aspartic acid, cystine, glycine, hydroxyproline, lysine, phenylalanine, serine, threonine, lyrosine and valine were significantly higher [p < 0.01] and of alanine lower [p <0.01] in patients compared to the corresponding value in control subjects. The data presented in this paper indicates some striking differences in the levels of many amino acids as indicated by mean plasma concentrations and daily excretions from urolithic patients and control subjects

Urolithiasis in childhood.

Clinical and laboratory findings in 41 cases of urolithiasis in children are presented. Males were more than females (9.25:1). Five patients had family history of urolithiasis. Clinical presentation was highly variable. Most of the stones were of mixed variety composed of calcium, phosphates and oxalates.

Serum and urinary uric acid levels in healthy subjects and in patients with urolithiasis.

Serum uric acid and 24-hour urine uric acid levels were determined in 47 patients with urolithiasis and in 177 healthy volunteers. The normal volunteers had serum and urinary uric acid levels of 6.0-6.4 mg/dl, 619.4-683.7 mg/day for males and 4.6-4.8 mg/dl, 531.5-589.6 mg/day for females. Uric acid levels in both serum and urine were higher in male volunteers than in female volunteers (p less than 0.05), whereas, among patients the ranges of serum and urinary uric acid levels were not significantly different between males and females (p greater than 0.05). However, the normal distribution of the determined small experimental data, was statistically different and is obviously reliable. Patients with urolithiasis showed significantly higher levels of serum uric acid (8.0 +/- 0.3 mg/dl) than healthy volunteers (5.5 +/- 0.1 mg/dl) (p less than 0.05), but showed no difference in urinary uric acid levels compared with healthy volunteers (p greater than 0.05). The highest number of urolithiasis in both male and female patients fell within the same age range of 41-50 years. The 24-hour urine pH of healthy volunteers showed a range of 5.1-7.0 while the patients with urolithiasis had a pH range of 4.6-7.0. It was also found that 33 per cent of patients had urine pH less than 5.0.