1,721,102 research outputs found
The etiology of esophageal cancer in high- and low- risk areas of Jiangsu province, China
No full text [Background]Esophageal cancer (EC) remains one of the most common and fatal malignancies worldwide. The geographic variation in EC occurrence is striking, and China is an area with one of the highest incidences of EC. A number of epidemiological studies have been conducted toward EC in the past decades, results suggested that tobacco smoking, alcohol drinking, unhealthy dietary factors and chronic injuries of the esophageal mucosa are important in the development of this disease. Genetic polymorphisms in enzymes involved in metabolism of carcinogens may also influence individual susceptibility. However, the effects of major lifestyle and hereditary risk factors on the development of EC remain poorly understood in China. Moreover, little attention has been paid to the etiological heterogeneity between similar areas with great risk gradient. [Methods]From 2003 to 2007, a large population-based case-control study of EC has been conducted in a selected high-risk area and a selected low-risk area of Jiangsu Province, one of the highest cancer incidence areas in China. In total, 1,520 cases and 3,879 controls were recruited. In this thesis, we evaluated the role of major lifestyle factors such as tobacco smoking, alcohol drinking and dietary factors, as well as inherited determinants including family history of cancer and genetic polymorphisms of alcohol-metabolizing related genes on the risk of EC. In addition, we investigated how much of the risk gradient between two areas could be explained by variation in the distributions of major risk factors. [Results] Tobacco smoking and alcohol drinking moderately increased the risk of EC, while the positive associations were only found among men but not among women. Dietary factors were observed to play important roles in the development of EC. Specific dietary habits i.e., fast eating speed, and hot eating and/or drinking substantially elevated EC risk and could explain more than 20% of EC cases each. High intake of salty foods and fried foods, low consumption of raw garlic were also observed to increase the risk of EC. In addition to environmental and lifestyle factors, we confirmed that a positive family history can significantly increase EC risk, and found the inheritance may modify the effect of some unhealthy lifestyles. Moreover, we further explored the relationship between EC and single nucleotide polymorphismsof ADH1B, ADH1C and ALDH2 genes. Results showed that the slow metabolizing ADH1B G allele, ADH1C G allele and ALDH2 A allele significantly increased EC risk among moderate-to-heavy alcohol drinkers, and a significant interaction was observed between ALDH2 gene and alcohol consumption. Lastly, we found that more than 60% of EC cases could be attributable to major lifestyle risk factors in the study population; furthermore, dissimilar distribution of several lifestyle factors, together with variations of hereditary factors may be largely responsible for the incidence difference between two study areas. [Conclusion]The findings in this thesis confirm that unhealthy lifestyles including smoking, alcohol drinking and some dietary factors are the predominant risk factors of EC in China, and a large proportion of incidence difference between regions at varying risk could be attributed to the different prevalence of lifestyle factors. As most of the identified risk factors are modifiable, these could be translated into risk reduction prevention programs in China, and a substantial proportion of new EC cases are expected to be prevented by eliminating or avoiding these risk factors in the population. </p
Fish consumption, does it beneficially affect markers of colorectal carcinogenesis?
No full textBackground: Fish consumption is possibly associated with a decreased risk of colorectal cancer, as has been shown in several observational studies. However, most of these studies did not discriminate between the effects of oil-rich and lean fish. To date, no randomized controlled trials (RCTs) have examined the possible beneficial effects of fish intake on colorectal cancer risk. Aim: The aim of this thesis was to investigate whether fish consumption beneficially affects markers of colorectal carcinogenesis. Methods and Results: In a case control study (363 cases, 498 controls), we studied the association of serum n 3 polyunsaturated fatty acid (PUFA) levels as a marker of oil rich fish intake with colorectal adenomas, a precursor lesion of colorectal cancer. We found that individuals with high serum long chain n 3 PUFA levels had a decreased risk of colorectal adenomas (odds ratio (OR) 0.67, 95% confidence interval (CI) 0.46; 0.96), whereas individuals with high serum n 6 PUFA levels had an increased risk of colorectal adenomas (OR 1.68, 95% CI 1.17; 2.42). In an RCT, we studied the effects of 3.5g/d fish oil (~1.5g/d n 3 PUFA) for 12 weeks on 19 serum inflammation markers in 77 healthy subjects and found that serum levels of these cytokines and chemokines were not changed. Finally, we studied the effects of increasing fish consumption compared with no additional fish, on markers of colorectal carcinogenesis in an RCT. Subjects (n=242), at an increased risk of colorectal cancer and those with no macroscopic signs of disease, were randomly allocated to receive dietary advice (DA) plus either two additional weekly portions of oil rich fish (salmon, ~1.4g/d n 3 PUFA) or lean fish (cod, ~0.09 g/d n 3 PUFA), or only DA for six months. We observed no change in apoptotic and mitotic cell numbers after the 6 months intervention with either salmon or cod compared with DA. Furthermore, colorectal genotoxicity, levels of cytokines and chemokines in colonic biopsies and feces, and fecal calprotectin were also not markedly changed after fish consumption. Only serum C reactive protein (CRP) levels were statistically significantly decreased after consumption of salmon ( 0.5 mg/l, 95% CI 0.9; 0.2) and cod ( 0.4 mg/l, 95% CI 0.7; 0.0) compared with DA. Conclusion: The results of this thesis do not provide strong evidence for beneficial effects of fish consumption on markers of colorectal carcinogenesis. <br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Dietary supplement use and colorectal tumors : from prevention to diagnosis
No full textBackground: Expert guidelines formulated by the World Cancer Research Fund and the American Institute for Cancer Research (WCRF/AICR) advised no use of dietary supplements for cancer prevention. However, it is unclear whether those recommendations also apply to populations at high risk for incident or recurrent colorectal tumors specifically, since dietary supplement use is ubiquitous in western countries where colorectal tumors are common. Furthermore, before the association between dietary supplement use and recurrence and survival in colorectal cancer patients can be examined, more information about the consistency of dietary supplement use is needed, as it is plausible that use varies over time after colorectal cancer diagnosis. This thesis focuses on the association between dietary supplement use and colorectal tumor risk and recurrence in the general population and in high-risk populations, and describes the consistency of use in patients who were diagnosed with colorectal cancer. Methods and results: First, we conducted a systematic literature review with meta-analyses of observational studies about the association between dietary supplement use and colorectal cancer risk. Our findings suggested inverse associations between multivitamins (use versus no use: RR=0.92; 95% CI 0.87–0.97, calcium supplements (use versus no use: RR=0.86; 95% CI 0.79–0.95) and colorectal cancer risk, while the association for other supplements and colorectal cancer risk was inconsistent. Second, we investigated the role of dietary supplements in recurrence of colorectal adenomas and advanced colorectal adenomas in a prospective cohort study of 565 patients with a history of sporadic colorectal adenomas. Dietary supplement was not associated with total adenoma recurrence (HR=1.03; 95% CI 0.79–1.34). Third, dietary supplement use and colorectal adenoma risk was examined in a prospective cohort study among 470 individuals with Lynch syndrome. No associations were found between dietary supplement use (HR=1.18; 95% CI 0.80–1.73) and colorectal adenoma risk in these individuals. Finally, in an ongoing prospective cohort study among incident colorectal cancer patients we evaluated whether dietary supplement use was consistent over time. Dietary supplement use was extensively assessed with a detailed self-administered questionnaire at diagnosis, six months and two years post-diagnosis. We observed that dietary supplement use among 160 colorectal cancer patients was common at all time points, but use was inconsistent from diagnosis to two years post-diagnosis. Conclusion: The results in this thesis do not point toward a preventive nor a harmful role for dietary supplement use in colorectal tumor risk and recurrence in the general population and in high-risk populations for colorectal cancer. However, dietary supplement use appeared to be inconsistent over time after colorectal cancer diagnosis, and use should be repetitively assessed over time. Since dietary supplement use is rising in countries where colorectal tumors are prevalent and the incidence of colorectal tumors will increase due to screening practices, research on the role of dietary supplement use for primary or tertiary prevention of colorectal tumors should continue in which use should be repetitively and comprehensively assessed. </p
'Bedroevende eetgewoonten jongeren zorgen over dertig jaar voor kanker'
No full textVeertig procent van alle gevallen van kanker die artsen jaarlijks vaststellen, is het gevolg van een slechte voeding en overgewicht. Voedingswetenschappers weten ondertussen vrij precies welke veranderingen in het dieet die gevallen zouden voorkomen, maar krijgen dat niet voor het voetlicht. “De sociale wetenschappen zijn nu aan zet”, zegt Ellen Kampman, die is gespecialiseerd in de relatie tussen voeding en kanke
Gezonde voeding belangrijk voor ex-patiënt
No full textDat er een relatie is tussen voeding en het ontstaan van kanker weten al veel mensen. Veel minder bekend is nog dat voeding ook tijdens en na behandeling van de ziekte invloed heeft op het herstel en de kwaliteit van leven. Ellen Kampman, hoogleraar aan Wageningen University en met financiering van de stichting Alpe d’HuZes ook aan de VU in Amsterdam, onderzoekt het
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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