The influence of high dose intake of ascorbic acid on the urinary excretion of oxalate was investigated in five healthy male volunteers. Oxalate was measured by a newly developed specific method using isotachophoresis. With intakes of 10 g ascorbic acid (5 X 2 g daily for 5 days; four subjects) mean urinary oxalate excretion was enhanced from about 50 mg to 87 mg (range 60 to 126 mg) per day. At least 25% of the ascorbic acid was absorbed and excreted with the urine. On discontinuing ascorbic acid administration, oxalate excretion returned to baseline values within 24 h. The time-course of oxalate excretion revealed that following the 3rd dose of 2 g ascorbic acid a plateau in urinary oxalate excretion was reached (0.6 microgram ml-1 min-1) which was not exceeded despite additional 2-g doses of ascorbic acid. On termination of ascorbic acid administration the oxalate excretion rate remained at this level for a further 6 h and then decreased to prestudy rates. No effect of high-dose ascorbic acid ingestion was found on the daily urinary excretion of creatinine, uric acid, and inorganic phosphate. Calcium excretion was slightly reduced. In comparison to the large amounts of ascorbic acid ingested, the increase in urinary oxalate excretion as measured by isotachophoresis in these healthy male volunteers was very low, and is thus similar to the change in urinary content of oxalate which results from consuming normal diets.

Allogeneic hematopoietic cell transplantation (HCT) is the treatment of choice for high-risk myeloid and lymphoid leukemias. Relapse after allogeneic HCT is associated with a dismal prognosis and further therapeutic options are limited. One potential curative approach is a second allogeneic HCT. However, there is no consensus about optimal transplant modalities, suitable patients, and entities. We performed a retrospective analysis of our institutional database to evaluate risk factors that influence survival after a second allogeneic HCT for the treatment of relapsed acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). We identified 40 patients (AML, n = 29; ALL, n = 11) that received a second allogeneic HCT at our institution. At time of second HCT, 48% of patients were in complete remission (CR). Current overall survival (OS) was 14/40 patients with a median follow-up of 64 months (range 4-140) of patients alive resulting in a Kaplan-Meier estimated 2-year event-free survival (EFS) and OS of 32%, respectively. Cumulative incidence of non-relapse mortality (NRM) and relapse at 2 years was 31 and 37%, respectively. We identified several independent risk factors influencing OS: > 6 months from first to second transplant (p = 0.02), complete remission prior to transplant (p = 0.003), and the subsequent occurrence of chronic graft-versus-host disease (p = 0.003) were associated with a significantly improved OS. In conclusion, our data suggest that a second allogeneic HCT is a curative treatment option for relapsed acute leukemias in selected patients.

A variety of procedures have been described in the literature for quantitative determination of urinary oxalate concentrations. However, a rapid and sufficiently simple technique for routine determinations is lacking. This study presents an isotachophoretic technique for measurement of urinary oxalate. Complete separation of the oxalate anion from accompanying ions is achieved in a PTFE-capillary between two electrodes according to differences in the net mobility. Short analysis time, little pretreatment of the urine samples, and extremely high resolving power and accuracy are the significant advantages of this newly developed method. This new technique was shown to be of significant value in studying the role of oxalate in urinary stone disease.

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