The Correlation between Certain Tryptophan Metabolites and the N-Nitrosamine Content in the Urine of Bilharzial Bladder Cancer Patients

Abstract

The present work is an up-to-date approach to study the correlation between the excretion pattern of tryptophan metabolites along the kynurenine pathway (after loading with 2 gm. L-tryptophan), and the N-nitrosamine content in urine of bilharzial bladder cancer patients. The control group was composed of healthy subjects who had no reported history of S. haematobium infection and no current bacterial cystitis. The N-nitrosamine content was determined by the colorimetric method of Eisebrand and Preussmann (1970). It was demonstrated that 64 per cent of the patients metabolized the tryptophan load abnormally and the others metabolized it almost normally. Moreover, the N-nitrosamines were present in 43 per cent of controls and 93 per cent of patients have these derivatives in higher values. The presence of an inverse correlation between certain tryptophan metabolites, shown previously to be bladder carcinogens, and the N-nitrosamine content, especially after loading, was interpreted in view of the possible conversion of some tryptophan metabolites into N-nitrosamines either under endovesical conditions or during the execution of the colorimetric determination of these compounds. Therefore, thorough investigation is urgently needed to study the origin of these urinary N-nitrosamines. Moreover, improved method(s) for their colorimetric determination are also urgently needed.

Promutagenic methylation damage in liver DNA of mice infected with Schistosoma mansoni

“…Such damage has been detected in tissue DNA from different populations in the world, in individuals suspected of exposure either to environmentally derived (38)(39)(40)(41)(42) or to endogenously formed (42) alkylating agents. Consistent with these observations, the presence of A'-nitroso compounds has been demonstrated in the urine of schistosome-infected subjects at levels significantly higher than that in normal individuals (43)(44)(45)(46)(47)(48). It was suggested that this is mainly due to endogenous formation arising from the urinary bacterial infection that invariably accompanies schistosomiasis (44,49,50).…”

Factors causing variation in urinary N‐nitrosamine levels in enterocystoplasties

“…Several others have detected nitrosamines in control groups; in a study of nitrosamine formation in relation to bladder infection, Radomski et al [18] detected small but significant dimethylnitrosamine formation in their control urine specimens, although the authors do not state from whom these control urine samples were obtained. In a study of the effects of schistosomiasis on urinary nitrosamine excretion, Tricker et al [30,34] found low levels of various nitrosamines in both German and Egyptian control groups, and Abdel‐Tawab et al [35] also found detectable total nitrosamines in six of 14 healthy Egyptian subjects. In contrast, Ellen et al [36] found no appreciable amounts of nitrosamines in the sterile urine of healthy volunteers.…”

Tumor microbiome – an integral part of the tumor microenvironment

“…The presence of N-nitrosamines was detected in 45% of control participants and 93% of patients. 64% of bladder cancer patients metabolized the tryptophan abnormally ( 174 ). 40 day-saccharin consumption led to an increased level of indican - tryptophan metabolite formed by bacterial action and p-cresol in rats.…”