Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied peripheral lymphocyte HPRT variant frequency and endogenous nitrosation in human populations exposed to various nitrate levels in their drinking water. Four test populations of women volunteers were compared. Low and medium tap water nitrate exposure groups (14 and 21 subjects) were using public water supplies with nitrate levels of 0.02 and 17.5 mg/l, respectively. Medium and high well water nitrate exposure groups (6 and 9 subjects) were using private water wells with mean nitrate levels of 25 and 135 mg/l, respectively. Higher nitrate intake by drinking water consumption resulted in a dose-dependent increase in 24-hr urinary nitrate excretion and in increased salivary nitrate and nitrite levels. The mean log variant frequency of peripheral lymphocytes was significantly higher in the medium well water exposure group than in the low and medium tap water exposure groups. An inverse correlation between peripheral lymphocyte labeling index and nitrate concentration of drinking water was observed. Analysis of N-nitrosamine in the urine of 22 subjects by gas chromatography-mass spectrometry revealed the presence of N-nitrosopyrrolidine in 18 subjects. Analysis of the mutagenicity of well water samples showed that a small number of the well water samples were mutagenic in the Ames Salmonella typhimurium test after concentration over XAD-2 resin. In conclusion, consumption of drinking water, especially well water, with high nitrate levels can imply a genotoxic risk for humans as indicated by increased HPRT variant frequencies and by endogenous formation of carcinogenic N-nitroso compounds from nitrate-derived nitrite.
 ...
PMID:Nitrate contamination of drinking water: relationship with HPRT variant frequency in lymphocyte DNA and urinary excretion of N-nitrosamines. 874 40

An unusual cluster of 8 breast cancer and 8 other malignant tumor cases (ovarian, uterus, lung, colon and brain tumors and malignant melanoma) developed in a period of 12 years among 98 nurses exposed to ethylene oxide (EtOx) for 5 15 years in a unit using gas sterilizer in a hospital of the archiepiscopal city of Eger, Hungary. EtOx concentration in air samples of the working area varied from 5 to 150 mg/m3. The question was, if there was any causal relationship between the elevated incidence of breast cancer and the EtOx exposure, the other possibility was, that this cluster appeared accidentally. EtOx is a human carcinogen, however, no increased breast cancer incidence in EtOx-exposed subjects was reported in the literature. We followed up for two consecutive years the 27 non cancer patients, EtOx-exposed nurses and 11 unexposed hospital controls with the aid of a multiple genotoxicology monitor including chromosomal aberration, sister-chromatide exchange, HPRT point mutation and DNA repair studies. The results were compared with data from 30 local historical controls, 48 historical controls from Budapest, 14 hospital controls and 9 EtOx exposed nurses from Budapest. Significantly high chromosome aberration yields (especially chromosome type exchanges) were alike detected in EtOx-exposed and the two other control groups in Eger. These results could not be interpreted as a consequence of EtOx exposure only, since in the EtOx-exposed group from Budapest, beside an increased total aberration frequency, the obtained exchange type aberration yields were as low as the historical controls. A plausible explanation can be the natural low dose radioactivity (222Rn) of the local tap-water due to a specific geological situation in Eger. The spontaneous breast cancer incidence in Hungary doubled in the last 10 years compared with the previous 20 years (1960 1980), especially in Eger. The appearance of the high breast cancer incidence in the hospital of Eger indicates the combined effect of EtOx and a more common local etiologic factor, such as the naturally radioactive tap-water. However, since the reported studies did not involve the investigation either of the genetic predisposition, or the effects of other possible environmental, occupational, and/or life style confounding factors, further studies (partly in progress) are necessary to clarify the importance of these factors.
 ...
PMID:Is breast cancer cluster influenced by environmental and occupational factors among hospital nurses in Hungary? 1039 63