Arsenic in drinking water and incidence of urinary cancers

To investigate the effects of a new nonNMDA antagonist on the trisynaptic pathways in the hippocampus, the author examined kainate(KA)-induced generalized seizures in rats. A novel nonNMDA antagonist, YM90K, showed the blockade of the Schaffer collaterals in 2-deoxyglucose study (2-DG) and that the CA1-2 pyramidal cells of the hippocampus were preserved seven days after the KA injections. On the other hand, the control and MK-801 (NMDA-antagonist) treated rats did not depress the Schaffer collaterals and showed persistent hypermetabolism of glucose in the CA1 pyramidal cell layer, where neurons were not preserved seven days later. 2-DG was useful to reveal the effects of nonNMDA antagonist on the KA-induced generalized seizures. This suggests that YM90K is a potent nonNMDA antagonist and that it has a neuroprotective effect in rats.     

Source of drinking water at home and site-specific cancer incidence in Washington County, Maryland

A nonconcurrent prospective study was conducted to investigate the postulated relationship between organic chemical by-products of water chlorination and risk of human cancer. Vital records and nonofficial census data available for each of nearly 31,000 study subjects were used to compute selected sex- and site-specific cancer incidence rates in a well-defined county population. Age, socioeconomic status, smoking history, source of drinking water at home, and other individual characteristics of the study population were examined in relation to the cancer rates. The drinking water source variable consisted of three historical cohorts, each distinguished by a different degree of exposure to chloroform and other chlorination byproducts. Incidence rates for cancer of the bladder among men and for cancer of the liver among women were nearly twofold higher in the drinking water cohort that had been supplied chlorinated surface water at home when compared to the cohort with a history of consumption of unchlorinated ground water. The differences, however, were not statistically significant. A complementary mortality study also suggested an association of chlorinated water with cancer of the liver and urinary tract. The findings in Washington County indicate the need for further studies of individuals with different histories of exposure to chlorinated and unchlorinated drinking water.     

Behavioral effects of chemicals in drinking water.

In Exp I, 42 Ss (mean age 30.4 yrs) tracked a moving target and monitored lights after receiving sublingual drops that contained either water, sodium nitrate (4.5, 45, 450, or 4,500 ppm), or sodium fluoride (.1, 1, 10, or 100 ppm). Dosage levels equaled, exceeded, or fell below those of municipal waters. In Exp II, 20 females performed this task after receiving sublingual drops of the same test substances in a repeated measures design; dosage levels equaled or exceeded levels found in municipal waters by 100 or 500 times. Neither type nor amount of chemical affected primary task performance; however, after receiving sublingual drops in Exp I, Ss paid less attention to lights on their right. In Exp II, Ss made more errors and had longer response latencies after they received moderate and very high concentrations of test substances. It is concluded that challenge testing is a safe but effective technique for provoking and studying reactions to chemicals when combined with a sensitive measure of sensorimotor performance. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship of natural incidence and radiosensitivity for bone cancer in dogs

A comparison of the risk coefficients for 239Pu- or 226Ra-induced bone cancer in two canine breeds, one with a relatively low (beagle) and the other with a very high (St. Bernard) natural incidence, indicated only slightly higher risk in the giant breed. The differences in risk for skeletal malignancy in 239Pu and 226Ra dogs were nonsignificant (p > 0.05). Likewise, the values of the 239Pu:226Ra "toxicity ratios" for these respective breeds, using bone cancer as the endpoint, were not significantly different at the 0.05 level. The anatomical distribution of the radiation-induced bone tumors tended to be a function of both the bone mass and the skeletal distribution of the radionuclide, not the site of predilection for naturally occurring bone neoplasia. Although the etiology of the higher natural incidence of bone cancer in the St. Bernard was not determined, several possible factors, including a higher osteoblastic activity level in the St. Bernards, are presented. These data suggest that making extrapolations of radiation-induced bone cancer risk from animals to humans is valid.     

Calcium and magnesium in drinking water and risk of death from rectal cancer

The possible association between the risk of rectal cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal-cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with a sample of deaths from other causes (986 controls), and the levels of calcium and magnesium in the drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes, and the controls were pair-matched to the cases by gender, year of birth and year of death. Compared with those with calcium levels below 22.0 mg/liter, the adjusted odd ratios (95% confidence interval) were 0.72 (0.53-0.98) for the group with water calcium levels between 22.0 and 40.8 mg/liter and 0.63 (0.45-0.87) for the group with calcium levels of 40.9 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and rectal cancer. The results of the present study show that there may be a significant protective effect of calcium intake from drinking water on the risk of rectal cancer.     

Relationship between schistosomiasis and bladder cancer

Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis, the clinicopathological identity of schistosome-associated bladder cancer, and extensive evidence in experimentally infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis. Of these, N-nitroso compounds appear to be of particular importance since they were found at high levels in the urine of patients with schistosomiasis-associated bladder cancer. Various strains of bacteria that can mediate nitrosation reactions leading to the formation of N-nitrosamines have been identified in the urine of subjects with schistosomiasis at higher intensities of infection than in normal subjects. In experimental schistosomiasis, the activities of carcinogen-metabolizing enzymes are increased soon after infection but are reduced again during the later chronic stages of the disease. Not only could this prolong the period of exposure to activated N-nitrosamines, but also inflammatory cells, stimulated as a result of the infection, may induce the endogenous synthesis of N-nitrosamines as well as generating oxygen radicals. Higher than normal levels of host cell DNA damage are therefore anticipated, and they have indeed been observed in the case of alkylation damage, together with an inefficiency in the capacity of relevant enzymes to repair this damaged DNA. In experimental schistosomiasis, it was also found that endogenous levels of host cell DNA damage were related to the intensity of infection. All of these factors could contribute to an increased risk of bladder cancer in patients with schistosomiasis, and in particular, the gene changes observed may have potential for use as biomarkers in the early detection of bladder cancer that may assist in alleviating the problem.     

Failure of monochloroacetic acid and trichloroacetic acid administered in the drinking water to produce liver cancer in male F344/N rats

The chlorinated acetic acids monochloroacetic acid (MCA) and trichloroacetic acid (TCA) are found as chlorine disinfection by-products in finished drinking-water supplies. TCA has been demonstrated to be a mouse liver carcinogen. A chronic study in which male Fischer 344/N rats were exposed for 104 wk to TCA and MCA in the drinking water is described. Animals, 28 d old, were exposed to 0.05, 0.5, or 2 g/L MCA, or 0.05, 0.5, or 5 g/L TCA. The 2.0 g/L MCA was lowered in stages to 1 g/L when the animals began to exhibit signs of toxicity. A time-weighted mean daily MCA concentration (MDC) of 1.1 g/L was calculated over the 104-wk exposure period. Time-weighted mean daily doses (MDD) based upon measured water consumption were 3.5, 26.1, and 59.9 mg/kg/d for 0.05, 0.5, and 1.1 g/L MCA, respectively; TCA MDD were 3.6, 32.5, and 363.8 mg/kg/d. Nonneoplastic hepatic changes were for the most part spontaneous and age related. No evidence of hepatic neoplasia was found at any of the MCA or TCA doses. The incidence of neoplastic lesions at other sites was not enhanced over that in the control group. Drinking water concentrations of > or = 0.5 g/L MCA produced a moderate to severe toxicity as reflected by a depressed water consumption and growth rate. A no-observed-effects level (NOEL) for carcinogenicity of 0.5 g/L (26.1 mg/kg/d) MCA was calculated. TCA at drinking water levels as high as 5 g/L produced only minimal toxicity and growth inhibition and provided a NOEL of 364 mg/kg/d. Our results demonstrate that under the conditions of this bioassay, MCA and TCA were not tumorigenic in the male F344/N rat.     

辽宁五龙金矿区花岗斑岩与成矿关系浅析

简略阐述了辽宁五龙金矿区的地质特征,并从时间、空间、构造等几个方面对花岗斑岩与矿体的关系进行了分析,总结出花岗斑岩脉在成矿过程中所起的作用,指出了下一步的找矿方向.     

Radium in drinking water and the risk of death from bone cancer among Ontario youths

Using a 4.1T whole body system, we have acquired 1H spectroscopic imaging (SI) data of N-acetyl (NA) compounds, creatine (CR), and choline (CH) with nominal voxel sizes of 0.5 cc (1.15 cc after filtering). We have used the SI data to estimate differences in cerebral metabolites of human gray and white matter. To evaluate the origin of an increased CR/NA and CH/NA ratios in gray matter relative to white matter, we measured the T1 and T2 of CR, NA, and CH in gray and white matter using moderate resolution SI imaging. In white matter the T2s of NA, CR, and CH were 233 +/- 27, 141 +/- 18, and 167 +/- 20 ms, respectively, and 227 +/- 27, 140 +/- 16, and 189 +/- 25 ms in gray matter. The T1 values for NA, CR, and CH were 1267 +/- 141, 1487 +/- 146, and 1111 +/- 136 ms in gray matter and 1260 +/- 154, 1429 +/- 233, and 1074 +/- 146 ms in white matter. After correcting for T1 and T2 losses, creatine content was significantly lower in white matter than gray (P < 0.01, t-test), with a white/gray content ratio of 0.8, in agreement with biopsy and in vivo measurements at 1.5 and 2.0T.     

Phosphorus and bacterial growth in drinking water

The availability of organic carbon is considered the key factor to regulate microbial regrowth in drinking water network. However, boreal regions (northern Europe, Russia, and North America) contain a large amount of organic carbon in forests and peatlands. Therefore, natural waters (lakes, rivers, and groundwater) in the northern hemisphere generally have a high content of organic carbon. We found that microbial growth in drinking water in Finland is highly regulated not only by organic carbon but also by the availability of phosphorus. Microbial growth increased up to a phosphate concentration of 10 micrograms of PO4-P liter-1. Inorganic elements other than phosphorus did not affect microbial growth in drinking water. This observation offers novel possibilities to restrict microbial growth in water distribution systems by developing technologies to remove phosphorus efficiently from drinking water.     

Relationship between drinking and increase in tail skin temperature of rats treated with L-5-hydroxytryptophan

Administration of L-5-hydroxytryptophan (25 micrograms/kg, s.c.), the immediate precursor of serotonin, to rats induces drinking and increases tail skin temperature. Decreases in both the metabolic rate (rate of oxygen consumption) and colonic temperature also occur. These responses are similar to those observed following acute administration of angiotensin II. However, both drinking and the increase in tail skin temperature are unaffected by prior administration of the non-peptide angiotensin II, AT-1 receptor antagonist, losartan potassium, but are partially attenuated by the beta-adrenoceptor antagonist, propranolol. This suggests that the responses are independent of the angiotensin AT-1 receptor but may be mediated, in part at least, by the beta-adrenoceptor. The hypothesis is presented that when either L-5-hydroxytryptophan or angiotensin II is administered to rats, they act centrally to reduce the set-point for body temperature regulation, thus resulting in the reflex activation of mechanisms that reduce body temperature, including an increase in tail skin temperature and a decrease in metabolic rate.     

An association of hardness of water with incidence of fatty liver syndrome in laying hens

Twenty-one samples of water were collected from commercial egg production farms in Georgial with or without a history of fatty liver syndrome. These samples plus a sample of water from the University of Georgia Poultry Farm were analyzed for various mineral elements by atomic absorption, direct reading emission spectroscopy and by neutron activation. Water samples from farms with a history of fatty liver syndrome had signficantly more calcium, magnesium, strontium, sodium, iron and barium than water samples from farms reporting no significant problem with fatty liver syndrome. Levels of manganese, boron, copper zinic and aluminum were not significantly different. Although the results do not prove that water quality is the cause of the disease, they do demonstrate an association of hardness of water with fatty liver syndrome that should be further investigated.     

Detection of psychotrophic aeromonads in drinking water

In the context of evaluating their pathogenic relevance, culture on solid media is the only approach presently suitable for culture of psychotrophic aeromonads from drinking water. In this respect, a check must be effected to ensure that the culture medium cannot engender selective culture losses for individual species. For this reason, media to which e.g. ampicillin has been added are unsuitable.     

Magnesium in drinking water and ischemic heart disease

The associations found in the general populations of a number of different countries are suggestive and warrant an integrated program of laboratory and epidemiologic research to reject or confirm the magnesium-IHD hypothesis. Singling out this particular risk factor has two justifications. First, as would be the case with any epidemiologic risk factor for IHD whose attributable risk was large enough to be detectable through epidemiology, applying that attributable risk to the vast annual morbidity and mortality from IHD would translate into tens of thousands of lives benefited and millions of dollars in hospital costs avoided per year. Second, this particular risk factor could conceivably be eliminated by an inexpensive supplementation program. For example, a low-sodium, higher-magnesium and -potassium table salt has been recommended and used in Finland for many years, during a period when the prevalence of hypertension in population surveys was said to decrease (117). Interventions which do not require behavioral change have always been the most cost-effective in public health. We therefore urge funding agencies to give priority to studies determining whether there are unforeseen adverse effects of magnesium for some population subgroups and whether the apparent benefit derived from low doses of magnesium in the development of IHD or IHD death is real. Furthermore, researchers should determine which chemical form of magnesium is best absorbed and most effective. We need to better understand the interrelation of various water and food constituents, as well as individual risk factors, in the pathogenesis of IHD. Susceptible individuals who are at higher risk of being depleted of magnesium need to be identified, and potential untoward effects of magnesium should be studied. Future research must provide better answers about low level waterborne magnesium before recommendations to the public can be made.     

Relationship between early side effects and therapeutic effects of clomipramine therapy in obsessive-compulsive disorder

Recognizing that the scientific method is as critical to cancer control as it is to basic laboratory research, the National Cancer Institute (NCI) established a well-defined, systematic strategy for attaining its cancer control goals and objectives. This strategy, operationalized in the early 1980s as a five-phase process, emphasized cancer control as a research science rather than a demonstration science. The five phases of NCI's cancer control research strategy progress from hypothesis development, to methods development, to controlled intervention trials, to defined population studies, and finally to demonstration and implementation programs. This research base provides the foundation for nationwide prevention and health services programs. The application of this five-phase approach to NCI's efforts to reduce morbidity and mortality attributable to tobacco use is described, and some of the challenges that faced the Institute in this process are identified. These experiences provide an important framework for other disciplines faced with the challenge of translating science into practice.     

Relationship between molecular weights of pectin and hypocholesterolemic effects in rats

Hypocholesterolemic activities and other properties of three different molecular weight pectin were examined. The low-molecular-weight pectin (M(r) not equal to 66,000) obtained by decomposition of original pectin (M(r) not equal to 750,000) had the properties of low viscosity and high solubility, but it lost hypocholesterolemic activities in rats. On the other hand, the medium-molecular-weight pectin (M(r) not equal to 185,000) had characteristics of both low viscosity and hypocholesterolemic activities.