Abdelbaset Anwer El-Aaser

Effect of soybean feeding on experimental carcinogenesis—III. Carcinogenecity of nitrite and dibutylamine in mice: a histopathological study

The potential carcinogenic effect of nitrosamine precursors, DBA (dibutylamine) and nitrite, was clearly demonstrated pathologically in the liver and bladder of male Swiss albino mice. Benign tumours were induced in the bladder with an incidence of 40%, and hepatomas were detected in the liver in 27% of the cases. The protective effect of soybean and ascorbic acid, added separately to the diet or to the drinking water respectively, was demonstrated by a marked reduction in dysplastic features and absence of tumour in both the liver and the urinary bladder.

A study on the aetiological factors of bilharzial bladder cancer in Egypt--1. Nitrosamines and their precursors in urine.

Abstract Endogenous nitrosamines and nitrosamines formed by deliberate chemical nitrosation of urine have been found to be much higher in urine of bilharzial infested and bladder cancer patients when compared with that of normal or cancer patients other than bladder cancer. Thiocyanate had been detected in all different types of urine samples. Nitrite was not found in normal urine but it had been detected in the urine of 3 out of 10 bilharzial patients. 7 out of 15 bladder cancer patients and 1 out of 14 non-bladder cancer patients.

Bladder carcinogenesis using bilharzia-infested Swiss albino mice

Abstract Experimental studies were carried out on female Swiss albino mice to evaluate the possible role of: liver injury, urine inborn carcinogens and local irritation of bladder mucosa in the development of bilharzial bladder cancer. In mice, the liver and intestine are only involved by parasite, but the urinary bladder is spared. Mice with induced liver injury due to either: bilharzial infestation alone, hepatocarcinogens alone (2-naphthylamine (2-NA) or 2-acetylaminofluorene (2-AAF)), or both together, did not develop bladder tumors. Also, mice receiving 1% indole (a tryptophan precursor) either alone, or after bilharzial infestation, did not show any change in bladder mucosa. Conversely, the insertion of glass beads in the bladder induced carcinomas in 26.6% of mice after 70 weeks. The induction of bladder tumors by glass beads was enhanced by 2-AAF treatment (40%), but not by bilharzia infestation (25%), 2-NA (27%) or indole (27%). The urinary bladders with glass beads were invariably the seat of bacterial infection ( E-coli and gram + ve cocci ) and showed epithelial hyperplasia and metaplasia.

A study on the etiological factors of bilharzial bladder cancer in Egypt. 6. The possible role of urinary bacteria.

A correlation was obtained between a positive nitrite test in urine and the severity of urinary bacterial infection. Bacteria isolated from the urine of bilharzial or bladder cancer patients were found to be rich in nitrate reductase activity. « Escherichia coli » was the most common microorganism isolated from these specimens. Urine and several urinary constituents activate bacterial nitrate reductase. β-Glucuronidase activity in the urine of patients with chronic « Schistosoma haematobium » infection and bladder cancer was measured and shown to be significantly greater than that of urine of normal control subjects. Urinary bacterial infection was shown to be the source of the increased urinary level of enzyme activity at pH 7.0.

Effect of Vicia faba and bran feeding on nitrosamine carcinogenesis and formation

The goal of this work was to study the effect of the most common Egyptian food items, Vicia faba beans (VF) and bran, on the carcinogenicity of dibutylnitrosamine (DBN) precursors (dibutylamine and nitrite). Mice receiving DBN precursors showed a delayed gain in body weight as well as decreased protein level and 5-nucleotidase activity. Acid ribonuclease, alkaline phosphatase, and DNA level and rate of synthesis were significantly increased compared with corresponding controls. Hepatomas and bladder papillomas developed in 60% and 40% of mice, respectively, after nine months of treatment. On the other hand, administration of VF or bran, in addition to DBN precursors, lessened the damage caused by DBN precursors alone, except DNA level and rate of synthesis were elevated. Alkaline phosphatase was also elevated when bran was administered with DBN precursors. However, these elevations were still less than corresponding elevations in mice receiving DBN precursors alone. The incidence of hepatoma was also reduced to only 20% for both groups. Meanwhile, incidence of bladder papillomas was only 20% in mice receiving VF in addition to DBN precursors, and bladder papillomas were completely absent in mice receiving bran in addition to DBN precursors. In vitro studies were also performed to clarify the effect of VF or bran on diphenylnitrosamine (DPhNA) and its formation from its precursors (diphenylamine and nitrite). The study revealed that VF and bran have the ability to eliminate nitrite and DPhNA from the reaction media and to reduce the rate of formation of DPhNA from its precursors. This reaction depends on the concentration and form of VF or bran and the duration of the reaction. Thus it is concluded that some naturally occurring food items, such as VF and bran, could protect humans against the hazardous effect of nitrosamines and their precursors.

A study on the aetiological factors of bilharzial bladder cancer in Egypt—2 Nitrosamines and their precursors in Egyptian dairy products

Abstract Milk, yoghourt and four types of cheese consumed by Egyptians have been analysed for the presence of nitrosamines, and that formed after deliberate chemical nitrosation. Two, three, seven out of ten samples of milk, cottage cheese, white cheese and six out of 9 samples of salted cheese respectively were contaminated with nitrosamines at g × 10 −9 level. Deliberate chemical nitrosation produced increasing amounts of both volatile and nonvolatile nitrosamines especially in blue cheese and salted cheese (cottage cheese stored in high concentrations of sodium chloride). The daily consumption of salted cheese and drinking water with high nitrate content, beside a heavily infected urinary bladder due to bilharzial infestation, may contribute to the observed high incidence of bladder cancer among Egyptian farmers.

A study on the etiological factors of bilharzial bladder cancer in Egypt: 5-urinary nitrite in a rural population.

Urinary nitrite was present in 5.6 % of 2379 individuals from a rural population infested with « Schistosoma haematobium ». A higher frequency was observed in symptomatic patients with active bilharzial cystitis (25 %) and patients with bladder cancer associated with schistosomiasis (66.2 %); conversely, urinary nitrite was absent in normal urban individuals. The frequency of urinary nitrite was higher in females (6.4%) than males (4.6%), and was more frequent in adults than extremes of age. The presence of urinary nitrite was associated with urinary infection and was commonly accompaned by cellular atypia in urine, in the form of dysplasia. Under these circumstances, carcinogenic nitrosamines are liable to be produced in the bladder from urinary nitrite and amines. These observation support the possible role of urinary bacterial infection, commonly associated with bilharzial cystitis, in bladder carcinogenesis.

Effect of soybean, Vicia faba, and vitamin C on the carcinogenicity of DMBA.

A single dose of 10 mg of 7,12-dimethylbenz[a]anthracene (DMBA), administered to rats through intragastric intubation, was sufficient to induce many biochemical and histopathological changes in their mammary tissue. Significant increases were observed in the activity levels of the enzymes acid ribonuclease, 5-nucleotidase, alkaline phosphatase, and beta-glucuronidase in mammary tissue homogenates of DMBA-treated rats after an experimental period of five months. Histopathological studies of the mammary tissue also revealed malignant epithelial tumors (cribriform carcinoma) induced among 85% of the treated rats, with an incidence of 4 tumors in 12 mammary glands. Nevertheless, administration of 30% soybean in the diet of rats or 5,000 ppm ascorbic acid in their drinking water in addition to DMBA revealed a significant chemoprotective effect against the carcinogenesis induced by DMBA alone. This chemoprotective effect was demonstrated by the normalization of the activity levels of the enzymes studied in mammary tissue homogenates, because most of the enzymes were maintained at near the levels in the control animals. The incidence and number of tumors were also decreased. Cribriform carcinoma was observed in 50% of the rats, and the incidence of the affected glands was 2 in 12 mammary glands among both groups. On the other hand, a less chemoprotective effect was observed due to Vicia faba administration.

Serum estrogen level in Egyptian breast cancer patients.

In menstruating 20-29 year old breast cancer patients, the total estrogen level showed a significant increase in the early follicular phase compared to normal healthy subjects. Such a difference was not observed in 30-45 year-old patients. A nonsignificant decrease was observed in the estradiol level of premenopausal breast cancer patients compared to normal healthy subjects. However, in postmenopausal breast cancer patients, the total estrogen level as well as the estradiol level showed a signicant increase compared to that of normal healthy subjects.