1,721,464 research outputs found
Colorectal cancer and long-term exposure to trihalomethanes in drinking water: A multicenter case-control study in Spain and Italy
No full textVillanueva, C.M., Gracia-Lavedan, E., Bosetti, C., Righi, E., Molina, A.J., Martín, V., Boldo, E., Aragonés, N., Perez-Gomez, B., Pollan, M., Acebo, I.G., Altzibar, J.M., Zabala, A.J., Ardanaz, E., Peiró, R., Tardón, A., Chirlaque, M.D., Tavani, A., Polesel, J., Serraino, D., Pisa, F., Castaño-Vinyals, G., Espinosa, A., Espejo-Herrera, N., Palau, M., Moreno, V., La Vecchia, C., Aggazzotti, G., Nieuwenhuijsen, M.J., Kogevinas, M
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Environmental exposure to polychlorinated biphenyls (PCBs) and breast cancer: a systematic review of the epidemiological evidence
No full textSome PCB congeners have shown oestrogenic effects, and this has raised concern that they may increase the risk of breast cancer. In this article we provide a quantitative review of the epidemiologic evidence on environmental exposure to PCBs and breast cancer risk. The vast majority of prospective and retrospective studies did not find any association between total PCB concentrations and breast cancer risk. No association was found for congeners in groups I (potentially oestrogenic) and III (biologically persistent phenobarbital-type cytochrome P450 inducers), according to the classification proposed by Wolff and Toniolo, while less consistent results were reported for group II (potentially antioestrogenic and immunotoxic, dioxin-like). Two studies found a threefold risk of postmenopausal breast cancer for women with an A2455G base change in exon 7 of the polymorphic CYP1A1 gene (a member of the cytochrome P450 family) and high PCB levels, compared with women with two wild-type alleles and low PCB, based however on very few cases. Thus, the epidemiological evidence does not support the hypothesis of an association of environmental exposure to PCBs in adulthood in the general population and risk of breast cancer, although uncertainties remain for selected subgroups of women or individual PCB congeners. (C) 2003 Lippincott Williams Wilkins
Wine and other types of alcoholic beverages and the risk of esophageal cancer
No full textObjective: To investigate the separate and combined effect of wine-drinking and other alcoholic beverages on esophageal cancer, in a high wine-consuming population. Design: Combined analysis of two hospital-based case-control studies. Setting: Major teaching and general hospitals in the greater Milan area and in the province of Pordenone, in northern Italy. Subjects: A total of 714 incident cases of esophageal cancer, and 3137 controls admitted to hospital for acute, non-neoplastic conditions, unrelated to alcohol consumption. Intervention: Trained interviews identified and questioned cases and controls using standardized structured questionnaires, including information on the average number of days per week each type of alcoholic beverages (wine, beer, spirits) was consumed, and the average number of drinks per day. Odds ratios (ORs) were calculated using unconditional multiple logistic regression equations. Results: With reference to total alcohol drinking, as compared to non- or moderate drinkers ( 12 drinks per day. Higher risks were observed for wine-only drinkers and the corresponding values were 1.70, 4.21, 8.76 and 17.90. After allowance for wine intake, no association was observed between beer and spirit drinking and esophageal cancer, in a population in which 80% of alcohol came from wine. Conclusion: The amount of ethanol determines the risk of esophageal cancer, and the most commonly used alcoholic beverage appear to be most strongly associated
Occupational exposure to polychlorinated biphenyls and cancer risk
No full textPolychlorinated biphenyls (PCBs) are a class of chemicals characterized by a long-term persistence and diffusion in the environment, and by bioaccumulation through the food chain. The highest exposures occurred in occupational cohorts through inhalation or skin absorption in work environments. These cohorts can therefore provide important information on health risk from exposure to PCBs in the general population. To provide comprehensive evidence on cancer risk from PCB exposure, we have thus reviewed the epidemiological studies on workers occupationally exposed to PCBs. Overall, no excess for all cancer mortality was observed in the six studies providing information (573 cancer deaths versus 630.4 expected, corresponding to a standardized mortality ratio (SMR) of 91). Among neoplasms potentially related to PCB exposure, there were 12 deaths from liver cancer compared with 9.5 expected (SMR=126). No excess was found for cancers of the breast (40 observed versus 47.4 expected, SMR=84) and of the lymphatic and haematopoietic system (51 observed versus 53.2 expected, SMR=96). Therefore, studies on occupational exposure to PCBs do not show any excess in all cancer mortality, or in mortality for specific cancer sites of interest. (C) 2003 Lippincott Williams Wilkins
Treatment of diverticular disease of the colon and prevention of acute diverticulitis: a systematic review
No full textBACKGROUND: Diverticular disease of the colon is a common disorder, characterized by recurrent symptoms and complications such as diverticulitis, requiring hospital admissions and surgery.
OBJECTIVE: This study aimed to systematically review the evidence for medical therapy of diverticular disease in reducing symptoms and preventing acute diverticulitis.
DATA SOURCES: MEDLINE and Embase databases (1966 to February 2010).
STUDY SELECTION: The studies selected were prospective clinical trials on uncomplicated diverticular disease of the colon.
INTERVENTIONS: Four investigators independently reviewed articles, extracted data, and assessed study quality according to standardized criteria.
MAIN OUTCOME MEASURES: The main outcomes measured were improvement in symptoms, complete remission of symptoms, and prevention of acute diverticulitis.
RESULTS: We identified 31 studies, including 6 placebo-controlled trials. The methodological quality of these studies was suboptimal. Only 10 trials provided a detailed description of the patient history, 8 assessed symptoms by the use of a validated questionnaire, and 14 appropriately defined inclusion and exclusion criteria. Only one long-term double-blind placebo-controlled study was identified. This reported a significant improvement in symptoms and greater prevalence of symptom-free patients at 1 year with fiber plus rifaximin in comparison with fiber alone. The efficacy of treatment in preventing acute diverticulitis was evaluated in 11 randomized trials. Four trials compared rifaximin plus fiber vs fiber alone and failed to show a significant difference between treatments. However, cumulative data from these trials revealed a significant benefit following rifaximin and fiber (1-year rate of acute diverticulitis: 11/970 (1.1%) vs 20/690 (2.9%); P = .012), but with a number needed to treat of 57, to prevent an attack of acute diverticulitis.
LIMITATIONS: : Heterogeneity of the study design, patients' characteristics, regimens and combination of studied treatment, and outcome reporting precluded the pooling of results and limited interpretation.
CONCLUSIONS: The treatment for diverticular disease relies mainly on data from uncontrolled studies. Treatment showed some evidence of improvement in symptoms, but its role in the prevention of acute diverticulitis remains to be defined
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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