Identification of a Carboxyl group at the Active Site of Barley MaIt Phosphatase

The dependence of the maximal velocity, Vm with pH for barley malt phosphatase has been studied from pH 4.0 to 5.4. The data show that an ionizable group in the enzyme-substrate complex with a pK2 of 4-4.6 is important for enzymic activity. These results suggest strongly the involvement of a carboxyl group of a glutamic or aspartic acid residue at the active site of this enzyme

Reduced Time for Urinary Alkalinization Before High-Dose Methotrexate with Preadmission Oral Bicarbonate

Purpose: Hydration and urinary alkalinization are essential for reducing renal dysfunction with high dose methotrexate (HDMTX). This report presents an analysis of institutional methods used to achieve adequate urinary alkalinization and output for patients receiving single agent HDMTX. Renal and metabolic parameters of tolerance were examined. Methods: Medical records of adult patients receiving HDMTX during the calendar years of 2008–2009 were retrospectively reviewed to determine the time to achieve urine pH\u3e7. Number of hospital days, bicarbonate dose, ordered hydration rate, urine output, and urine pH were assessed. A survival analysis model was run for time to urine pH\u3e7 using preadmission oral bicarbonate as a predictor variable and including a frailty term. Observational statistics were performed for other parameters. Results: The analysis included 79 encounters for ten patients. Urine pH\u3e7 was achieved more rapidly in patients receiving preadmission oral bicarbonate (P¼0.012). The number of patients receiving HDMTX on the same day as admission was greater for those receiving preadmission oral bicarbonate (47%) in comparison to those who did not (2%), and they spent less time in the hospital. A standard regimen for hydration and urinary alkalinization based on this project is reported. The nature and frequency of adverse events were as expected for this treatment. Conclusion: At our institution, the time to achieve urinary alkalinization was reduced for patients receiving preadmission oral bicarbonate which facilitated chemotherapy infusion on the same day as admission and decreased the number of calendar days that patients stayed in the hospital