1,720,959 research outputs found
Increase of protein and lipid oxidation during hyperhomocysteinemia induced by methionine oral loading
No full textIntroduction: Hyperhomocysteinemia (HHcy) is a well-defined risk factor for vascular disease by a not still well clear molecular mechanism. It is known a pro-oxidant effect of Hcy “in vitro” in presence of metal ions (Fe e Cu). To assay a similar effect in vivo, we studied plasma markers of lipid and protein oxidation during hyperhomocysteinemia induced by methionine oral load.Materials and methods: 16 subjects (aged 79 14 years; 16f), 14 of which underwent a methionine (100 mg/Kg) oral load were studied; in all patients we assayed total plasma HCY, malonaldehyde (MDA) and conjugates dienes (DIE), oxidized protein (PTOX) (carbonilic groups) in basal conditions and after 4, 6, 8 and 24 hours from the oral load. In the two subjects who did not take the methionine load (controls), were made the same assays with the same timing of the probands. In all subjects we assayed basal and after 8 hours from the methionine load total plasma antioxidant (ANTOX) capacity.Results: table shows values (mean DS) of considered parameters in subjects who underwent the methionine loadParameterBasal4 h6 h8 h24 hHcy (nmol/ml)20.7 11.550.6 19.157.2 25.561.6 28.3 45.3 30.7PTOX (nmol/mg prot.)0.38 0.210.49 0.270.68 0.390.68 0.270.58 0.40DIE(nmol/ml)493 163562 181526 233590 202545 182MDA(nmol/ml)1.66 0.801.91 0.942.19 1.321.96 0.931.95 0.99ANTOX(nmol/ml)1.76 +/- 0.511.38 +/- 0.86 Conclusions: HHCY induces a correspondent increase of plasma oxidation makers. In absence of HHCY, no significant modifications were observed. This data, together with the reduction of ANTOX in correspondence of maximum plasma HCY increase, are suggestive of pro-oxidant effect of HHCY in vivo
Peroxidation indices and total antioxidant capacity in plasma during hyperhomocysteinemia induced by methionine oral loading
No full textHyperhomocysteinemia is a risk factor for vascular disease, although its mechanism of action is not fully clear. Different experimental studies have suggested that homocysteine (Hcy) exerts a pro-oxidant effect in the presence of metal ions (Fe and Cu). To test for a similar effect in vivo, we studied plasma markers of lipid and protein oxidation du ring hyperhomocysteifiemia induced by an oral methionine load. Twenty-nine subjects (aged 61 +/- 25 years; 17 women), 25 of whom underwent oral methionine (100 mg/kg) loading, were studied; in every case, we measured total plasma Hey, malondialdehyde (MDA), conjugated dienes (DIE), and oxidized protein ([PTOX] carbonylic groups) in basal conditions and 4, 6, 8, and 24 hours after methionine loading. Four participants acted as controls. In every case, we also measured total plasma antioxidant capacity (ANTOX) in basal conditions and 8 hours after methionine loading. Eight hours after methionine loading, plasma Hey increased from 17.6 +/- 11.4 to 54.3 +/- 31.6 nmol/ml, PTOX from 0.33 +/- 0.18 to 0.71 +/- 0.33 nmol/mg protein, DIE from 493 +/- 163 to 590 +/- 202 optical density units, and MDA from 1.66 +/- 0.81 to 2.1 +/- 0.93 nmol/ml. There was a significant correlation (Spearman ́s r) between Hey and both PTOX (r = .86, P = .01) and MDA (r = .47, P < .05) 8 hours after methionine loading. No significant modifications of the plasma parameters were found during the observation period in controls. ANTOX at 8 hours was significantly (paired ttest) reduced in probands (from 1.74 +/- 0.59 to 1.14 +/- 0.55 mmol/ml, P = .014); no significant difference was observed for plasma ANTOX in controls. Hyperhomocysteinemia due to oral methionine loading induced an increase in plasma oxidation markers. In the absence of hyperhomocysteinemia. no significant modifications were observed. These findings, together with the decrease in ANTOX and the corresponding increase in total plasma Hey, are consistent with a pro-oxidant effect of acute hyperhomocysteinemia in vivo. Copyrigh
Hyperhomocysteinemia and related factors in 600 hospitalized elderly subjects
No full textHyperhomocysteinemia (HHcy) is a metabolic disorder frequently occurring in the elderly population. Recently several reports have suggested abnormalities in homocysteine (tHcy) metabolism implicating HHcy as a metabolic link in the multifactorial processes characterizing many geriatric illnesses-with special emphasis on atherosclerotic vascular diseases and cognitive impairment. The present study was undertaken in a large sample of elderly hospitalized subjects to determine (1) the prevalence of HHcy, (2) the association of HHcy with vascular and cognitive disorders, and (3) the factors independently predicting Hhcy. Six hundred elderly subjects (264 men and 336 women; mean age, 79 +/-9 years) were randomly chosen from those admitted as inpatients over a period of 3 years. In all patients, body mass index (BMI), mid-upper arm muscle area (MUAMA), plasma cholesterol, triglycerides, total proteins, albumin, lymphocyte count, creatinine, homocysteine (fasting and 4 hours after methionine oral load), serum vitamin B-6, vitamin B-12, and folate concentrations were measured. The presence of disease or use of medications known to affect homocysteine plasma levels were also recorded. The mean fasting tHcy level was 16.8 +/- 12 mu mol/L in the whole sample, 18.18 +/- 13.25 mu mol/L in men, and 15.86 +/- 12.14 mu mol/L in women (P=.005 men v women). The mean Hcy level 4 hours after methionine load was 37.95 +/- 20.9 in the whole sample. Prevalence of hyperhomocysteinemia (fasting Hcy greater than or equal to 15 mu mol/L or 4 hours after methionine load greater than or equal to 35 mu mol/L) was 61% (365/600) (67% in men and 56% in women, P<.05). HHcy was rarely (8%) an isolated disorder; in addition to diabetes (20%), renal failure (48.2%), and malnutrition (20.2%), it was often associated with heart failure (30%), malignancies (20.5%), and the use of diuretics (56%) and anticonvulsant drugs (13%). Plasma homocysteine progressively increases across subjects from those with no diabetes, malnutrition, renal failure, obesity, inflammatory bowel disease, heart failure to those with 1, 2, or more concurrent diseases. Multiple stepwise regression analysis showed that 72% of plasma total fasting tHcy variability was explained by age, serum folate, plasma albumin, use of diuretics, and renal function (measured as plasma creatinine clearance). In conclusion, the present study documents that hyperhomocysteinemia, in elderly hospitalized patients is (1) a common finding, (2) frequently associated with vascular and cognitive disorders, and (3) probably a secondary phenomenon in most cases. The major predictor of high plasma homocysteine levels were age, serum folate, plasma albumin, plasma creatinine clearance, and use of diuretic drugs. These variables explain a large proportion of plasma Hcy variability. Copyrigh
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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