Indigenous and contaminant microbes in ultradeep mines

Rock, air and service water samples were collected for microbial analyses from 3.2 kilometres depth in a working Au mine in the Witwatersrand basin, South Africa. The approximately metre-wide mined zone was comprised of a carbonaceous, quartz, sulphide, uraninite and Au bearing layer, called the Carbon Leader, sandwiched by quartzite and conglomerate. The microbial community in the service water was dominated by mesophilic aerobic and anaerobic, alpha-, beta- and gamma-Proteobacteria with a total biomass concentration approximately 10(4) cells ml(-1), whereas, that of the mine air was dominated by members of the Chlorobi and Bacteroidetes groups and a fungal component. The microorganisms in the Carbon Leader were predominantly mesophilic, aerobic heterotrophic, nitrate reducing and methylotrophic, beta- and gamma-Proteobacteria that were more closely related to service water microorganisms than to air microbes. Rhodamine WT dye and fluorescent microspheres employed as contaminant tracers, however, indicated that service water contamination of most of the rock samples was < 0.01% during acquisition. The microbial contaminants most likely originated from the service water, infiltrated the low permeability rock through and accumulated within mining-induced fractures where they survived for several days before being mined. Combined PLFA and terminal restriction fragment length profile (T-RFLP) analyses suggest that the maximum concentration of indigenous microorganisms in the Carbon Leader was < 10(2) cells g(-1). PLFA, 35S autoradiography and enrichments suggest that the adjacent quartzite was less contaminated and contained approximately 10(3) cells gram(-1) of thermophilic, sulphate reducing bacteria, SRB, some of which are delta-Proteobacteria. Pore water and rock geochemical analyses suggest that these SRB's may have been sustained by sulphate diffusing from the adjacent U-rich, Carbon Leader where it was formed by radiolysis of sulphide.

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Mild head injury increasing the brain's vulnerability to a second concussive impact

OBJECT

Mild, traumatic repetitive head injury (RHI) leads to neurobehavioral impairment and is associated with the early onset of neurodegenerative disease. The authors developed an animal model to investigate the behavioral and pathological changes associated with RHI.

METHODS

Adult male C57BL/6 mice were subjected to a single injury (43 mice), repetitive injury (two injuries 24 hours apart; 49 mice), or no impact (36 mice). Cognitive function was assessed using the Morris water maze test, and neurological motor function was evaluated using a battery of neuroscore, rotarod, and rotating pole tests. The animals were also evaluated for cardiovascular changes, blood-brain barrier (BBB) breakdown, traumatic axonal injury, and neurodegenerative and histopathological changes between 1 day and 56 days after brain trauma. No cognitive dysfunction was detected in any group. The single-impact group showed mild impairment according to the neuroscore test at only 3 days postinjury, whereas RHI caused pronounced deficits at 3 days and 7 days following the second injury. Moreover, RHI led to functional impairment during the rotarod and rotating pole tests that was not observed in any animal after a single impact. Small areas of cortical BBB breakdown and axonal injury. observed after a single brain injury, were profoundly exacerbated after RHI. Immunohistochemical staining for microtubule-associated protein-2 revealed marked regional loss of immunoreactivity only in animals subjected to RHI. No deposits of beta-amyloid or tau were observed in any brain-injured animal.

CONCLUSIONS

On the basis of their results, the authors suggest that the brain has an increased vulnerability to a second traumatic insult for at least 24 hours following an initial episode of mild brain trauma.

Effects of mammographic density and benign breast disease on breast cancer risk (United States)

BACKGROUND

Having either a history of benign breast disease, particularly atypical hyperplasia or extensive mammographic breast density, is associated with increased breast cancer risk. Previous studies have described an association between benign breast disease histology and breast density. However, whether these features measure the same risk, or are independent risk factors, has not been addressed.

METHODS

This case-control study, nested within the prospective follow-up of the Breast Cancer Detection Demonstration Project, evaluated both benign histologic and mammographic density information from 347 women who later developed breast cancer and 410 age- and race-matched controls without breast cancer. Multivariate logistic regression analyses provided maximum-likelihood estimates of the odds ratios (OR) and 95% confidence intervals (CI) to evaluate the relative risk of breast cancer associated with each exposure.

RESULTS

Adjusting for mammographic density, the OR for atypical hyperplasia was 2.1 (95% CI: 1.3-3.6), and adjusting for benign breast histology, the OR for > or = 75% density was 3.8 (95% CI: 2.0-7.2). Women with nonproliferative benign breast disease and > or = 75% density had an OR of 5.8 (95% CI: 1.8-18.6), and women with < 50% density and atypical hyperplasia had an OR of 4.1 (95% CI: 2.1-8.0).

CONCLUSIONS

In this study, both benign breast disease histology and the percentage of the breast area with mammographic density were associated with breast cancer risk. However, women with both proliferative benign breast disease and > or = 75% density were not at as high a risk of breast cancer due to the combination of effects (p = 0.002) as women with only one of these factors.

Excess incidence of squamous cell esophageal cancer among US Black men: role of social class and other risk factors

Data from a population-based case-control study were used to evaluate the relation between social class factors and squamous cell esophageal cancer and the extent to which alcohol, tobacco, diet, and low income contribute to the higher incidence among Black men than among White men in the United States. A total of 347 male cases (119 White, 228 Black) and 1,354 male controls (743 White, 611 Black) were selected from three US geographic areas (Atlanta, Georgia, Detroit, Michigan, and New Jersey). Cases were residents of the study areas aged 30-79 years who had been diagnosed with histologically confirmed esophageal cancer between 1986 and 1989. The adjusted odds ratios for subjects with annual incomes less than $10,000 versus incomes of $25,000 or more were 4.3 (95% confidence interval: 2.1, 8.7) for Whites and 8.0 (95% confidence interval: 4.3, 15.0) for Blacks. The combination of all four major risk factors-low income, moderate/heavy alcohol intake, tobacco use, and infrequent consumption of raw fruits and vegetables-accounted for almost all of the squamous cell esophageal cancers in Whites (98%) and Blacks (99%) and for 99% of the excess incidence among Black men. Thus, lifestyle modifications, especially a lowered intake of alcoholic beverages, would markedly decrease the incidence of squamous cell esophageal cancer in both racial groups and would narrow the racial disparity in risk. Further studies on the determinants of social class may help to identify a new set of exposures for this tumor that are amenable to intervention.

The excess incidence of squamous cell esophageal cancer among us black men. Role of social class and other risk factors

PURPOSE: To investigate the relationship between social class factors and squamous cell esophageal cancer and the extent to which alcohol, tobacco, diet, and social class contribute to the five-fold higher incidence among black than white men in the United States.METHODS: Interviews were conducted with 347 incident cases of squamous cell esophageal cancer (119 white males and 228 black males) and 1354 population-based controls (743 white males and 611 black males) from Atlanta, Detroit, and New Jersey. Risks were estimated using unconditional logistic regression controlling for potential confounders.RESULTS: Elevated risks of squamous cell esophageal cancer were associated with indicators of low social class, especially low annual income. The adjusted odds ratios (ORs) for subjects with incomes < $10,000 versus incomes of $25,000 or more were 4.3 (95% CI = 2.1-8.7) for whites and 8.0 (95% CI = 4.3-15.0) for blacks. The combination of all four major risk factors: annual income less than $25,000, moderate/heavy use of alcohol, use of tobacco for six months or longer, and consumption of less than 2.5 servings of raw fruits and vegetables per day accounted for almost all of the squamous cell esophageal cancers in whites (98%) and blacks (99%), and for 99% of the excess incidence among black men.CONCLUSIONS: Lifestyle modifications, especially a lower intake of alcoholic beverages, would markedly decrease the incidence of this cancer in both races and narrow the racial disparity in risk. Further studies into the determinants of social class may help identify a new set of exposures for this tumor that are amendable to intervention.

Menopausal estrogen and estrogen-progestin replacement therapy and breast cancer risk

CONTEXT

Whether menopausal hormone replacement therapy using a combined estrogen-progestin regimen increases risk of breast cancer beyond that associated with estrogen alone is unknown.

OBJECTIVE

To determine whether increases in risk associated with the estrogen-progestin regimen are greater than those associated with estrogen alone.

DESIGN

Cohort study of follow-up data for 1980-1995 from the Breast Cancer Detection Demonstration Project, a nationwide breast cancer screening program.

SETTING

Twenty-nine screening centers throughout the United States.

PARTICIPANTS

A total of 46355 postmenopausal women (mean age at start of follow-up, 58 years).

MAIN OUTCOME MEASURE

Incident breast cancers by recency, duration, and type of hormone use.

RESULTS

During follow-up, 2082 cases of breast cancer were identified. Increases in risk with estrogen only and estrogen-progestin only were restricted to use within the previous 4 years (relative risk [RR], 1.2 [95% confidence interval [CI], 1.0-1.4] and 1.4 [95% CI, 1.1-1.8], respectively); the relative risk increased by 0.01 (95% CI, 0.002-0.03) with each year of estrogen-only use and by 0.08 (95% CI, 0.02-0.16) with each year of estrogen-progestin-only use among recent users, after adjustment for mammographic screening, age at menopause, body mass index (BMI), education, and age. The P value associated with the test of homogeneity of these estimates was .02. Among women with a BMI of 24.4 kg/m2 or less, increases in RR with each year of estrogen-only use and estrogen-progestin-only use among recent users were 0.03 (95% CI, 0.01-0.06) and 0.12 (95% CI, 0.02-0.25), respectively. These associations were evident for the majority of invasive tumors with ductal histology and regardless of extent of invasive disease. Risk in heavier women did not increase with use of estrogen only or estrogen-progestin only.

CONCLUSION

Our data suggest that the estrogen-progestin regimen increases breast cancer risk beyond that associated with estrogen alone.

Interaction of ACE inhibitors and aspirin in patients with congestive heart failure

The beneficial effects of aspirin and ACE inhibitors in CHF have been well established; however, the clinical relevance of the drug interaction between these agents remains controversial. The exact mechanism of this interaction is not known, but the proposed theory involves the opposing effects of aspirin and ACE inhibitors on prostaglandins. The medical literature dose not provide a clear picture of the clinical significance of concomitant aspirin and ACE inhibitor therapy. Some studies suggest that the dose of aspirin may influence the clinical relevance of this interaction. Short-term use of aspirin > or = 300 mg was found to attenuate enalapril's effect on hemodynamic variables. However, short-term use of low-dose aspirin (236 mg) produced no effect on blood pressure. Patients with CHF who require therapy with both aspirin and ACE inhibitors may want to consider low doses of aspirin with active monitoring of hemodynamic parameters. However, chronic aspirin therapy in patients with CHF on concomitant ACE inhibitors has not been adequately studied at this time. Data concerning a possible interaction between angiotensin II receptor antagonists and aspirin are not available. However, because angiotensin II receptor antagonists do not interfere with kininase II activity, it would seem unlikely that aspirin would interact similarly with an angiotensin II receptor antagonist. Further studies are needed to examine the exact mechanism of the interaction between aspirin and ACE inhibitors. These studies should focus on the effects of different doses of aspirin given concomitantly with ACE inhibitors in patients with CHF. Prospective, randomized studies are also needed to determine the long-term effects of aspirin and ACE inhibitor therapy on mortality in patients with CHF.

Dietary factors and the risk of squamous cell esophageal cancer among black and white men in the United States

OBJECTIVES

To investigate dietary factors for squamous cell esophageal cancer and whether these factors may contribute to the five-fold higher incidence of this cancer in the black versus white population of the United States.

METHODS

Data from a food frequency questionnaire were analyzed for 114 white men and 219 black men with squamous cell esophageal cancer, and 681 white and 557 black male controls from three areas of the United States who participated in a population-based case-control study of esophageal cancer.

RESULTS

Protective effects were associated with intake of raw fruits and vegetables (odds ratio for high versus low consumers = 0.3 in both white and black men) and use of vitamin supplements (especially vitamin C; odds ratio for high versus low consumers = 0.4 in both races), with the frequency of consumption of raw fruits and vegetables and vitamin supplements being greater for white than black controls. In addition, elevated risks were associated with high versus low intake of red meat (OR = 2.7 for blacks and 1.5 for whites) and processed meat (OR = 1.6 for blacks and 1.7 for whites), with the levels of consumption being greater for black than white controls.

CONCLUSIONS

In the United States, these dietary factors may contribute in part to the much higher incidence of squamous cell esophageal cancer among black compared to white men.

Drinking practices and risk of squamous-cell esophageal cancer among Black and White men in the United States

To evaluate whether the fivefold greater incidence rate of squamous-cell esophageal cancer in Black compared with White men is due to type of alcoholic beverage consumed or to other qualitative differences in alcohol consumption, we conducted a population-based case-control study with 373 males diagnosed with squamous-cell esophageal cancer (124 Whites and 249 Blacks) and 1,364 male controls (750 Whites and 614 Blacks) from three geographic areas in the United States. Included were all histologically confirmed cases newly diagnosed from 1 August 1986 through 30 April 1989, among White and Black men aged 30 to 79 years. Risks varied to some extent according to type of alcohol used, with beer a stronger contributor in Whites, and wine and liquor stronger contributors in Blacks. However, most of the differences in the odds ratios by type of alcohol and race were eliminated after controlling for average weekly amount of total alcohol consumed. Thus, while alcohol use in all forms is an important risk factor for squamous-cell esophageal cancer in Whites and Blacks, type of alcoholic beverage used does not appear to account for the racial differences in incidence.

Multiple myeloma among Blacks and Whites in the United States: role of cigarettes and alcoholic beverages

In the United States, the incidence rates of multiple myeloma in Blacks are more than twice those in Whites, but the etiology of this cancer is poorly understood. A population-based case-control interview study of 571 subjects (365 White, 206 Black) with multiple myeloma and 2,122 controls (1,155 White, 967 Black) living in three areas of the United States (Georgia, Michigan, New Jersey) offered the opportunity to investigate the relationship with smoking and alcohol drinking and to evaluate whether these factors might contribute to the excess risk of multiple myeloma in Blacks. For Blacks and Whites of either gender, there were no significantly elevated risks associated with ever use of cigarettes or alcoholic beverages and no consistent patterns with either intensity or duration of use. These data support previous studies indicating that smoking and drinking are not related causally to the risk of multiple myeloma, and thus cannot account for the racial disparity in incidence rates.