1,720,961 research outputs found
A Study on Methylation Changes in Mismatch Repair Gene (hMLH1) in Esophageal Cancer Patients of Kashmir Valley
Get PDFThe Study was a Case Control undertaken to understand the etiology of esophageal cancer in the population of Kashmiri origin. This case control study was designed to assess the relationship of promoter hypermethylation of Mismatch Repair Gene MutL homolog 1 (hMLH1) with esophageal cancer. Also further an association of hypermethylation of hMLH1 gene with esophageal cancer in relation to clinicopathological features of Gender and Age was evaluated.
Esophageal cancers are one of the most fatal cancers in the world and are considered to be the eighth most common malignancy. The prognosis of Esophageal Cancer is poor as its symptoms appear in the late stage of the disease. This cancer is one of the most prevalent cancers in Jammu and Kashmir region of India and has multi-factorial etiology involving dietary habits, genetic factors, and gene environmental interactions. Genetic abnormalities of proto-oncogenes, tumor suppressor genes and mis-match repair genes have been demonstrated to be involved frequently in esophageal carcinogenesis; chronic inflammation leading to malignancy in the esophagus may be due to errors in mismatch repair (MMR) genes such as hMLH1. Inactivation of the hMLH1 gene expression by aberrant promoter methylation plays an important role in the progression of esophageal carcinoma. In the present study the role of hMLH1 promoter methylation in 50 histopathologically confirmed esophageal cancer tissues and compared it with corresponding histopathologically confirmed Normal adjacent tissues was studied by methylation-specific polymerase chain reaction (MS-PCR).
For evaluating the status of hMLH1 promoter hypermethylation and its association with Esophageal Cancer, a methylation specific polymerase chain reaction (MS-PCR) was used. DNA was extracted and treated with sodium bisulfite which converts unmethylated cytosines to uracil and does not affect methylated cytosines. The modified DNA was amplified in MS-PCR reaction by applying methylated and unmethylated promoter specific primers. Universally methylated DNA was used as positive control and DNA from normal lymphocytes used as negative control. The MS-PCR products were run on 3% agarose and bands were visualized under UV light. It was found that the frequency of promoter region hypermethylation of mismatch repair gene (hMLH1) in esophageal cancer cases was 56% (28 out of 50) and in histopathologically confirmed normals it was 15% (03 out of 20).Statistically the association of promoter region hypermethylation of mismatch repair gene (hMLH1) with esophageal cancer was evaluated using χ2-test (chi-square test) with odds ratio and was found significant and the p0.05.From the data it was concluded that The Frequency of MutL homolog 1 (hMLH1) gene promoter region hypermethylation was found high in Esophageal Cancer Cases of above 40 years of age (56%) and in controls (16%) and was significant as p0.05 and was evaluated by Fishers exact test.
Observing similar level of hMLH1 promoter hypermethylation in patients with Esophageal Cancer in this high risk region and comparing it with other parts of the world could support the hypothesis that a common molecular mechanism might be involved in tumorigenesis of Esophageal Cancer. As regards promoter hypermethylation status of mismatch repair gene hMLH1 shows a significant increase in promoter region hypermethylation of esophageal cancer patients of Kashmiri origin as compared to controls was observed. This became more apparent when the data for hypermethylation was interpreted taking Gender into consideration here it was seen that Males shows higher frequency of promoter region hypermethylation as compared to females which was earlier reported in literature and also patients of above 40 years of age shows high frequency compared to below 40 years of age
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Evaluation of Thymidylate Synthase Polymorphisms in ALL patients of Kashmir
Get PDFAcute lymphoblastic leukemia (ALL) is a malignant disorder of lymphoid progenitor
cells, affects both children and adults, with peak prevalence between the ages of 2 and 5
years, and is the most common paediatric cancer. Genetic susceptibility to leukemias can
be related to the polymorphisms in multiple genes and consistent with this paradigm;
several polymorphisms have been identified in the pathogenesis of lymphoid
malignancies. The enzyme encoded by Thymidylate Synthase (TS) gene is a crucial
enzyme in the folate metabolism and plays an important role in the DNA synthesis and
repair pathway. Impairments in this enzyme have been associated with chromosome
breaks and fragile site induction, which in turn have been associated with the
development of lymphoid malignancies including leukemias. The aim of the study was to
investigate whether the tandem repeat polymorphism in the TS promoter region is a risk
factor for the development of acute lymphoblastic leukemia in Kashmiri population. The
repeat polymorphism in the TS gene was evaluated in 72 ALL cases and 82 (age, sex and
region matched, non malignant) controls by PCR analysis of DNA obtained from the
blood of the subjects and direct sequencing of the PCR products. We observed that the
TS triple tandem repeat (3R) allele frequency was 73.75 % in the controls and 67.91% in
cases. This difference in frequency was found to be statistically insignificant with a P =
0.2713(P> .05). The TS 2R/2R genotype was found to be present in 13.88% of the cases
and 9.75% of the controls, the 2R/3R variant in 31.94% of the cases and 31.70% of
controls, and the 3R/3R genotype in 47.22% of cases and 56.09% of controls.
We observed that although the proportion of patients who were homozygous for the TS
tandem repeat(3R/3R) was lower in cases than in controls, the difference was not
statistically significant when using 2R/2R genotype as a reference (OR= 0.5913; 95% CI,
0.2111-1.657; P = 0.3143). Similarly, we observed the frequency of the heterozygous
genotype (2R/3R) when compared with 2R/2R genotype was not much different between
the cases and controls hence, statistically insignificant (OR=0.7077; 95% CI, 0.2389-
2.097; P= 0.5317). Thus, our study suggests that there is no association between TS
tandem repeat polymorphism and the development of ALL in Kashmiri population.
However these findings need to be substantiated with larger sample size to clarify the real
contribution of this gene in the susceptibility to ALL in different world populations
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