Correlations of beta-aminoisobutyric acid in 8 hour and 24 hour urinary samples determined by dual column gas chromatography.

The correlations of beta-aminoisobutyric acid values in 8 hour and 24 hour urinary samples from 23 healthy persons were determined. beta-AIB in the 8 hour urinary samples was measured by gas chromatography and the 24 hour excretion was calculated from the results of three 8 hour determinations. Simultaneous determinations of urinary creatinine were performed by Jaffe's reaction. Based on the 8 hour values of urinary beta-AIB the results demonstrated a constant excretion of beta-aminoisobutyric acid within the 24 hour periods in both low and high excretors. The precision in distinguishing low and high 24 hour excretors of beta-AIB by using 8 hour values was 91%. If 8 hour values of beta-AIB were related to creatinine the same precision for this calculated ratio was 96.5%. However, for high excretors of beta-AIB, failures were 24.5% by using the 8 hour excretion of beta-AIB as indicator, but only 6.5% by using the ratio.

Urinary pseudouridine and beta-aminoisobutyric acid in patients with low grade urothelial tumours. Relations between excretion and tumour recurrence.

The simultaneous 24 hours excretion of pseudouridine and beta-aminoisobutyric acid in the urine from patients treated for low grade urothelial tumours has been determined and related to tumour recurrence inside of 6 months after the determinations. The results of 53 assays in 39 patients without clinical signs of recurrence at the time of the detrmination showed a high excretion of pseudouridine in 53% and of beta-aminoisobutyric acid in 28.5% of the assays. Recurrences appeared more often after a high urinary pseudouridine (53.5%) than after a low, but the difference was not statistically significant (p more than 0.05) and more often after a low urinary beta-aminoisobutyric acid (52.5%) than after a high (p less than 0.01). The highest incidence of recurrence was in patients with a simultaneously high urinary pseudouridine and a low urinary beta-aminoisobutyric acid. Seventy per cent of these excretion patterns were from patients, who developed a recurrence before 6 months (p less than 0.002).

A study on the clinical significance of urinary beta-aminoisobutyric acid in patients with urothelial tumours.

Urinary beta-aminoisobutyric acid (beta-AIB) has been measured in 141 patients with urothelial tumours and 60 controls. Ninetyone of the patients have been followed-up for an average period of about 2 years, which included many determinations of the beta-AIB excretion. Thirtysix patients died during the control periods. Urinary beta-AIB was found to be significantly correlated to the grade of tumour cell dysplasia, but not to the clinical tumour stage. The treatment had no major influence on the excretion. Characteristic changes in the excretion preceding high-grade tumour recurrences are demonstrated. Autopsy findings with tumour tissue in the urinary tract and distant metastases were significantly correlated to a low urinary beta-AIB in the terminal phase of the disease. The results are discussed in relation to the degradation of thymine, the dual origin of beta-AIB and the tumour-host metabolism. It is concluded, that urinary beta-AIB can contribute to the graduation of malignancy, but is not valuable as a general screening procedure for urothelial cancer.