The correlation between certain tryptophan metabolites and the N-nitrosamine content in the urine of bilharzial bladder cancer patients.

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.

In vitro studies of the effect of metal ions, EDTA and their mixtures on kynurenine aminotransferase and kynurenine hydrolase.

In the present study use was made of the chelating ability of EDTA and the activating property of some metal ions Ca(II), Mg(II) or Mn(II) to counteract the inhibitory effect of Cu(II), Co(II), Pb(II) or Zn(II) ions on the B6-dependent kynurenine hydrolase and on kynurenine aminotransferase. These may be of help in studying the therapeutic trials in the treatment of metal poisoning. EDTA was able to counteract the inhibitory effect of Cu(II) or Co(II) on kynurenine aminotransferase and partially counteract the inhibitory effect of Cu(II), Co(II) on kynurenine aminotransferase and partially counteract the inhibitory effect of Cu(II), Co(II), Pb(II) or Zn(II) ions on kynurenine hydrolase. The difference in the response of the two B6-dependent enzymes to EDTA is attributed to the difference in the functional groups involved in the active site(s) of the two apoenzymes. Moreover, Mn(II), Ca(II) and Mg(II) ions have the ability to counteract some of the inhibitory effect of these metal ions.

beta-Glucuronidase in schistosomal intestinal polypi of the colon.

The results of a clinical, histopathological and biochemical study on twenty patients with schistosomal polyposis of the large bowel and ten patients with normal colon as a control are reported. The biopsy showed clearly the absence of any malignant or premalignant changes in all the twenty bilharzial patients. Results of the biochemical study showed that there is a statistically significant increase in beta-glucuronidase activity in schistosomal polypi compared to normal mucosa. This enzymatic activity is absent in schistosoma ova. The causes of the increase in the enzyme activity have been attributed to leucocytic infiltration present in schistosomal granulomata and possible to some degree of liver disfunction. The protein content of the excess mucus present in the colon could also activate the enzyme. Our results also show that the increased enzyme activity does not necessarily have carcinogenic properties. We did not come across a single case of malignancy even in a patient with very high level of enzyme activity (11615 units) or in those patients with a prolonged history of the disease.

The spontaneous urinary excretion of tryptophan metabolites "via kynurenine" in women with regards to the prepuberty, sexual maturity and menopause.

High values of anthranilic acid, 3-OH-kynurenine, xanthurenic acid and 3-OH-anthranilic acid are observed in the spontaneous urinary excretion of tryptophan metabolites in girls in the prepubertal age. The highest differences are between the 3-hydroxy metabolites especially the 3-hydroxykynurenine. On the other hand, this metabolic excretion in postmenopausal women is statistically identical to that of women in sexual maturity.

The effect of environment on tryptophan metabolism "via kynurenine" in oral contraceptives users.

We have studied tryptophan metabolism "via kynurenine" in women who were oral contraceptives users, living in two different egyptian environments: in the city of Alexandria or in a rural area near Tanta and, in comparison, in control groups of women living in the same environments but who were not contraceptives users. In the non contraceptives users of Tanta we have registered a higher elimination of some metabolites (anthranilic acid, kynurenic acid, xanthurenic acid and 3-OH-anthranilic acid) which might be related to the way of life and environment. The pattern of the kynurenine pathway metabolites of the contraceptives users (studied 1, 3 and 12 months after contraceptives administration) shows some differences with respect to the controls, both in the spontaneous elimination and in that after tryptophan load. These differences are especially evident for anthranilic acid glucuronide, kynurenine and kynurenic, anthranilic and xanthurenic acids. Some differences may be observed after 1 month of contraceptives administration. The effect of tryptophan oral load is superimposed on those of environment and contraceptives use; in the spontaneous elimination of tryptophan metabolites an accomodation to the contraceptives administration is evident. The discrepancies between some of our results and those of the literature might be related to the influence of environmental factors and of the way of life.

Studies on the effectiveness of liver and bacterial beta-glucuronidase enzymes in the hydrolysis of urinary beta-glucosiduronides of some tryptophan metabolites.

The effectiveness of Escherichia coli and bovine liver beta-glucuronidases in the hydrolysis of the urinary beta-glucosiduronides of tryptophan metabolites was studied. Moreover, the effect of the prolonged contact of these conjugates to the urinary enzyme was investigated in the first and second voiding urine samples. It is found that both enzymes have no important role in releasing the free carcinogens from their glucosiduronides. The presence of free carcinogens could be attributed to the spontaneous hydrolysis of some labile conjugates. However, the prolonged contact of the freely active substances during the sleeping hours with the epithelium of the bladder may enhance the process of bladder carcinogenicity. The increased accumulation of these metabolites in the first voiding urine could be interpreted in terms of their rate of excretion rather than by the enzymatic hydrolysis of their conjugates.

Studies on the effectiveness of mammalian and bacterial beta-glucuronidase enzymes in the hydrolysis of urinary beta-glucosiduronides of some tryptophan metabolites excreted in urine.

The effectiveness of E. coli and bovine liver beta-glucuronidases in the hydrolysis of the urinary beta-glucosiduronides of tryptophan metabolites was studied. Some of these metabolites demonstrate carcinogenic activity in the mouse bladder. Moreover, the effect of the prolonged contact of these conjugates to the urinary enzyme was investigated in the first and second voiding urine samples. The former urine was that retained in the bladder during sleep (about 8 hours) and the latter was collected 3 hours after the first. It is found that both enzymes have no important role in releasing the free carcinogens from their glucosiduronides. The presence of free carcinogens could be attributed to the spontaneous hydrolysis of some labile conjugates. However, the prolonged contact of the freely active substances during the sleeping hours with the epithelium of the bladder may enhance the process of bladder carcinogenicity. The increased accumulation of these metabolites in the first voiding urine could be interpreted in terms of their rate of excretion rather than by the enzymatic hydrolysis of their conjugates.