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The influence of genetic polymorphisms of fibrinogen genes on changes in total fibrinogen and fibrinogen gamma prime concentrations over time in black South Africans
Get PDFMSc (Dietetics), North-West University, Potchefstroom Campus, 2014INTRODUCTION AND AIM - Cardiovascular disease is globally a major risk factor for morbidity and mortality. It is caused by various factors, one of which is an abnormal haemostatic process. Fibrinogen is a haemostatic factor that is considered to be an independent risk factor for cardiovascular disease. Elevated fibrinogen can be caused by environmental and genetic factors which increase the risk of the occurrence of thrombosis. The fibrinogen y' chain, which is one of the three chains of fibrinogen, has two different variants, the yA and y’. The presence of the fibrinogen y’ chain has been associated with thrombotic disorders. Many studies have investigated the fibrinogen variables in Caucasian individuals, but only a few such studies have been conducted on non-Caucasian individuals. The genetic diversity of ethnic groups differs and could cause differences in the fibrinogen variables between these groups. Fibrinogen is known to increase with age; therefore to explain changes over time in fibrinogen concentrations it was also important to investigate whether genetic determinants and possible gene–environment interactions influenced fibrinogen over time. In this study the main aim was to determine the change in the fibrinogen variables over a five-year period within a black South African cohort subdivided according to genotypes associated with fibrinogen variables, and to determine whether the observed changes were modulated by environmental factors.
PARTICIPANTS AND METHODS - Data [baseline (n=2010) and follow-up (n=1288)] were collected in the Prospective Urban and Rural Epidemiology (PURE) study during 2005 and 2010 from apparently healthy black men and women aged between 35 and 65 years and residing in rural or urban settlements. Experimental methods included analysis of fibrinogen and fibrinogen y’ concentrations, single nucleotide polymorphisms (SNPs) and determination of environmental factors associated with the fibrinogen variables. RESULTS - The fibrinogen variables increased significantly from 2005 to 2010 in both the rural and urban participants, as well as in both men and women. The major environmental factors that affected the fibrinogen variables were C-reactive protein (CRP), interleukin-6 (IL-6), body mass index (BMI), glycated haemoglobin (HbA1c), age, blood lipids, human immunodeficiency virus (HIV) and tobacco use. Fibrinogen increased consistently from 2005 to 2010 in the respective genotypes of all SNPs analysed, except in the FGG 9340 T>C homozygous mutant carriers. Fibrinogen y’ also increased in general in most genotypes from 2005 to 2010, except in the FGG 10034 C>T mutant allele carriers, where a decrease was observed. It was determined that CRP was the only environmental factor that influenced the change in fibrinogen over time and that FGG 10034 C>T was the only SNP that influenced the change in fibrinogen y’ over the five years. Four gene–environment interactions also influenced fibrinogen on a cross-sectional level, i.e. FGA 2224 G>A with age, FGB Arg448Lys with HIV status, FGB 1643 C>T with urbanisation and FGB 1038 G>A with HbA1c. Only the FGG 9340 T>C with HbA1c interaction was found to predict change in fibrinogen concentrations over the five years. CONCLUSION - Both environmental and genetic factors significantly influenced the fibrinogen variables cross-sectionally as well as prospectively. It was clear that the influence of the environmental factors was mediated by genetic polymorphisms and vice versa, as can be seen by the gene–environment interactions found in this study. An important finding of this study was that the interaction of HbA1c with two SNPs on fibrinogen variables may explain the known inconsistent relationship found between fibrinogen concentrations and diabetes.Master
The relevance of specific c–reactive protein genetic variants towards cardiovascular disease risk in a black South African population undergoing an epidemiological transition
Get PDFThesis (MSc (Nutrition))--North-West University, Potchefstroom Campus, 2013.Introduction: In Africa, it is estimated that cardiovascular disease (CVD) will affect approximately 1.3 million people per annum over the following 20 years. C-reactive protein (CRP) is a predictor of CVD risk and certain CRP gene polymorphisms can result in altered CRP concentrations. The distribution of CRP gene polymorphisms is ethnic-specific and extrapolating information from other populations to the black South African population, reported to harbour considerable genetic variation, should be avoided. This highlights the fact that genetic research among black South Africans is necessary. Objectives: The main aim of this dissertation was to determine the association between various polymorphisms (reported and novel [single nucleotide polymorphisms (SNPs)] within the CRP gene with CRP concentrations [measured as high sensitivity (hs)-CRP concentrations] in a black South African population undergoing an epidemiological transition. Interactions between specific CRP polymorphisms and certain environmental factors on hs-CRP concentrations were also investigated.
Methods: This cross-sectional study (n=1,588) was nested within the Prospective Urban and Rural Epidemiological (PURE) study. Genotyping was performed using Illumina VeraCode technology on the BeadXpress® platform. Hs-CRP concentrations were measured by the use of a sequential multiple analyser computer (SMAC) through a particle-enhanced immunoturbidometric assay. Results: All the SNPs adhered to the assumptions of Hardy-Weinberg equilibrium, although the distribution of several SNPs differed from that reported in other population groups. Three SNPs (rs3093058, rs3093062 and rs3093068) were associated with a significant (p ≤ 0.05) increase in CRP concentrations. Five SNPs (rs1205, rs1341665, rs2794520, rs7553007 and rs2027471) were associated with a significant (p ≤ 0.05) decrease in CRP concentrations. This difference in effect was most probably due to changes in gene function brought about by the localisation of these SNPs in the CRP gene. Men and urban individuals were more likely to present with significant associations between the SNPs investigated and CRP concentrations. The difference in the prevalence of the alleles associated with higher CRP concentrations in this population compared to non-African populations could possibly explain the increased CRP concentrations that are observed in the black South African population. Gene-gender (rs1205, rs1341665 and rs2027474) as well as gene-environmental (rs3093068) interactions were also observed. Conclusions: CRP concentrations are in themselves a complex trait and there are many factors at play that influence their expression. Numerous factors (both genetic and environmental) are involved and no single factor acting alone is likely to have enough of an influence to be used as a clinical diagnostic test of CRP concentrations. These results provide valuable information on the regulation of CRP in a black South African population as well as contribute to the literature of CRP on a global level.Master
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
Dietary strategies to treat hyperhomocysteinaemia based on the biochemistry of homocysteine: a review
Get PDFHyperhomocysteinaemia is implicated in various diseases, including cardiovascular disease and cancer. Several conditions influence the concentration of homocysteine (Hcy), including demographic, genetic and lifestyle factors. With regard to the latter, dietary components may be manipulated as Hcy can be remethylated to methionine by folate, or metabolised by other one‑carbon nutrients, such as betaine and its precursor, choline. This metabolic interplay enables the nutritionist or dietitian to be able to lower Hcy concentrations cost‑effectively by tailoring an individual’s diet, or by food enrichment and fortification strategies. Evidence supports the safety and benefits of Hcy reduction by simple dietary intervention. B vitamins, and betaine and choline intake lower Hcy, whereas methionine and certain beverages (coffee, tea and alcohol) increase it. Therefore, dietary determinants of Hcy raise the prospect of a simple, inexpensive and safe means of treating and/or preventing diseases contingent on this sulphur
‑containing protein
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
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