Metabolic evaluation of stone-forming (SF) patients is based on the determination of calcium, oxalate, citrate, uric acid and other parameters in 24-h urine samples under a random diet. A reliable measurement of urinary oxalate requires the collection of urine in a receptacle containing acid preservative. However, urinary uric acid cannot be determined in the same sample under this condition. Therefore, we tested the hypothesis that the addition of preservatives (acid or alkali) after urine collection would not modify the results of those lithogenic parameters. Thirty-four healthy subjects (HS) were submitted to two non-consecutive collections of 24-h urine. The first sample was collected in a receptacle containing hydrochloric acid (HCl 6 N) and the second in a dry plastic container, with HCl being added as soon as the urine sample was received at the laboratory. Additionally, 34 HS and 34 SF patients collected a spot urine sample that was divided into four aliquots, one containing HCl, another containing sodium bicarbonate (NaHCO(3 )5 g/l), and two others in which these two preservative agents were added 24 h later. Urinary oxalate, calcium, magnesium, citrate, creatinine and uric acid were determined. Urinary parameters were also evaluated in the presence of calcium oxalate or uric acid crystals. Mean values of all urinary parameters obtained from previously acidified 24-h urine samples did not differ from those where acid was added after urine collection. The same was true for spot urine samples, with the exception of urinary citrate that presented a slight albeit significant change of 5.9% between samples in HS and 3.1% in SF. Uric acid was also not different between pre- and post-alkalinized spot urine samples. The presence of crystals did not alter these results. We concluded that post-delivery acidification or alkalinization of urine samples does not modify the measured levels of urinary oxalate, calcium, magnesium, creatinine and uric acid, and that the change on citrate was not relevant, hence allowing all parameters to be determined in a single urine sample, thus avoiding the inconvenience and cost of multiple 24-h urine sample collections.

Seventy-two cartons of yoghurt were sampled three times at monthly intervals from four different local manufacturers. Total counts were close to 6 x 10 7 cells g -1 of yoghurt. Yeast counts varied from 1 to 2,700 g -1 . There was no evidence of systematic contamination at source but this longitudinal study revealed that ad hoc contamination and improper storage led to the higher yeast counts. Contamination was generally higher in the hotter months but was lower overall than reported from other countries. A total of 577 yeast isolates were identified belonging to ten species. The most abundant yeasts were, in order, Debaryomyces hansenii, Saccharomyces cerevisiae, Mrakia frigida, Hansenula spp., Candida parapsilosis, Debaryomyces castellii and Candida maltosa. The psychrophilic yeast Mrakia frigida is reported for the first time in yoghurts. Low level contamination with Monilia and Penicillium species was found in a few samples. Growth tests suggested that ability to ferment sucrose, growth at 5ºC and in the presence of 300 µg g -1 sorbate preservative, were the three most significant physiological properties to account for these yeasts in yoghurts. The data also suggest that warmer weather and inadequate refrigeration are the principal causes of higher levels of contamination, increased diversity and change in microbial flora.

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This study analyzed early changes in trough blood cyclosporine concentrations and cyclosporine exposures after kidney transplantation. Seventy-two patients who received cyclosporine-based immunosuppressive therapy were intensively monitored (CO) during the first 6 months after transplantation. Full pharmacokinetic studies were performed at day 4, and months 2, 3, and 6 after transplantation. Mean steady-state, dose-adjusted trough cyclosporine blood concentrations increased from 1.1 f 0.60 (day 7) to 2.0 i 1.20 ng/ml per mg (day 30, P < 0.01). Steadystate, dose-adjusted cyclosporine exposure parameters (CO, Cmax, AUC, Cavg, and Cl2) were significantly lower at day 4 than at months 2, 3, and 6 after transplantation (P < 0.01). Initial cyclosporine doses produced target concentrations in only 30% of the patients at day 3. C2 was the single concentration that showed high and consistent correlation with serial AUC measurements (y2 2 0.76). The incidence of biopsy-proven acute rejection was 20.5% and was not associated with ethnicity, HLA mismatch, adjunctive therapy, or blood trough cyclosporine concentrations below 200 ng/ml at day 3. Significant time-dependent increases in steadystate cyclosporine exposure occur during the first month after kidney transplantation. Due to the low relative bioavailability early after surgery, higher doses and more frequent cyclosporine dose adjustments are necessary to produce target exposures early after transplantation.

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