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Erythrocyte amino acids in health and renal failure and their association to the IGF-I/IGFBP-1 axis [Elektronisk resurs]
No full textAbnormalities in amino acids (AA) metabolism in uraemia have mainly been reported to occur in plasma and muscle. No investigation has been undertaken to evaluate the AA levels in plasma, muscle and red blood cells (RBC) simultaneously, although the RBC pool of free AA constitutes a large proportion of the free AA in blood, and RBC are involved in the interorgan transport of AA. Moreover, in most of the earlier studies reporting RBC AA levels in different clinical conditions, including uraemia, AA were determined in whole blood, which also includes AA from white blood cells and platelets. In this thesis, muscle, plasma and RBC were sampled simultaneously and reversed-phase HPLC was used to determine free AA in these compartments. RBC were separated from plasma, white blood cells and platelets, and then hemolysed, deproteinised, filtered and analysed for AA. In study I, 27 healthy subjects were investigated in order to establish reference muscle, plasma and RBC free AA levels. These results may assist the clinical investigator when comparing the AA profiles in muscle, plasma and RBC in various disease conditions and also for evaluating the effect of various physiological stimuli on AA concentration changes in these compartments. In study II, muscle biopsy and blood samples (plasma and RBC) were obtained from 38 haemodialysis (HD), 22 continuous peritoneal dialysis (CPD) and 10 end stage renal failure patients for determination of free AA and the results compared to data obtained from study I. Several AA abnormalities in all three compartments were observed in the uraemic patients End-stage renal failure is characterised by both disturbed protein metabolism and changes in the IGF-I/IGFBP-1 axis. Protein synthesis and degradation are regulated by a number of hormones, and hormonal regulation represents an important process to maintain coordination of nutrient flows among the various organs. In study III, a possible association between changes in AA levels and the IGF-I/IGFBP-1 axis in end-stage renal failure was investigated in 30 HD patient who had no clinical signs of malnutrition. RBC glutamate and plasma IGFBP-1 levels were elevated in the HD patients and they were positively correlated. Since high IGFBP-1 reduces the bioavailability of IGF-I, reduced bioavailability of IGF-I, due to elevated IGFBP-1 levels, may be linked AA levels and the IGF-I/IGFBP-1 axis in end-stage renal failure was investigated in 30 HD patients who had no clinical signs of malnutrition. RBC glutamate and plasma IGFBP-1 levels were elevated in the HD patients and they were positively correlated. Since high IGFBP-1 reduces the bioavailability of IGF-I, reduced bioavailability of IGF-I, due to elevated IGFBP-1 levels, may be linked to the regulation of glutamate distribution in uraemia. Increased post-absorptive plasma glutamate levels have been linked to conditions with loss of body cell mass. In studies IV and V investigated in a rodent model how the protein content in the diet (IV and V) and moderate renal failure (V) change the intra-and extracellular AA levels (particularly glutamine and glutamate), and whether these changes are associated with circulating IGF-I and IGFBP-1 levels (IV and V) and/or muscle ASP/DNA ratios (V). Elevated RBC glutamate levels found in rats fed a low protein diet (IV) may indicate alterations in glutamate flux and interorgan nitrogen transport. The RBC and muscle glutamate relationships to the IGF-I/IGFBP-1 axis and muscle ASP/DNA ratio support the proposal that RBC glutamate or RBC glutamine/glutamate ratio may be used as markers of catabolism, and that changes in the bioavailability of IGFs are linked to the regulation of glutamate distribution. In summary, this thesis has demonstrated that AA determination in RBC is a simple and sensitive method for detecting AA alterations, and that RBC have an important and yet not fully clarified role in AA and protein metabolism in catabolic conditions such as uraemia and protein restriction, in both man and rat
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
Extracellular volume changes and blood pressure levels in hemodialysis patients
No full textBACKGROUND: Despite the use of highly efficient antihypertensive drugs (AHD), blood pressure (BP) is poorly controlled in the vast majority of hemodialysis (HD) patients. Many of them show no reduction in nocturnal BP, a finding that is associated with left ventricular hypertrophy. The aim of the study was to investigate the effect of the removal of a fluid overload on BP by monitoring the ambulatory BP during 48 hours in 16 hypertensive HD patients treated with AHD. Our aim was to obtain a gradual reduction in post-HD body weight (BW) over a period of 3 to 4 months. METHODS: During a period of 3-4 months, the postdialysis BW was reduced as the minimal tolerable BW was gradually achieved by slightly increasing the ultrafiltration volume. The Na concentration in the dialysate was reduced from 143-141 mmol/L to 139-138 mmol/L. Extracellular volume (ECV) was measured with a multiple-frequency bioimpedance analyzer (Xitron 4000B, Xitron Technologies Inc., San Diego, CA, USA). Based on the change in ECV, the patients were subdivided into two groups: group 1 with a reduction in ECV (n = 10), and group 2 with no reduction (n = 6). At the start of the study, BW, BP, and AHD in group 1 and group 2 were virtually identical. RESULTS: Group 1 showed a significant reduction during the entire 48-hour period in systolic (156 +/- 16 mmHg vs. 140 +/- 14 mmHg, P = 0.030) and diastolic BP (97 +/- 12 mmHg vs. 87 +/- 9 mmHg, P = 0.026) as well as in mean arterial pressure (MAP, 117 +/- 13 vs. 105 +/- 10 mmHg, P = 0.027). This reduction was more marked during the night (systolic BP 156 +/- 15 mmHg vs. 138 +/- 14 mmHg, P = 0.007; diastolic BP 97 +/- 12 mmHg vs. 85 +/- 9 mmHg, P = 0.009) than during the day (157 +/- 18 mmHg vs. 142 +/- 15 mmHg, P = 0.067; diastolic BP 97 +/- 13 mmHg vs. 90 +/- 9 mmHg, P = 0.126). A significant reduction in systolic load also occurred during the entire 48-hour period (76 +/- 24% vs. 46 +/- 28%, P = 0.043) as well as in night systolic load (75 +/- 21% vs. 41 +/- 30%, P = 0.015) and night diastolic load (67 +/- 32% vs. 39 +/- 31%, P = 0.030). AHD were stopped in eight and reduced in two patients. There were no significant reductions in BP and AHD in group 2. CONCLUSIONS: The removal of excess fluid is necessary for adequate BP control and especially for the reduction in elevated BP during the night
How to improve the biocompatibility of peritoneal dialysis solutions (Without jeopardizing the patient’s health)
Get PDFPeritoneal dialysis (PD) is an important, if underprescribed, modality for the treatment of patients with end-stage kidney disease. Among the barriers to its wider use are the deleterious effects of currently commercially available glucose-based PD solutions on the morphological integrity and function of the peritoneal membrane due to fibrosis. This is primarily driven by hyperglycaemia due to its effects, through multiple cytokine and transcription factor signalling—and their metabolic sequelae—on the synthesis of collagen and other extracellular membrane components. In this review, we outline these interactions and explore how novel PD solution formulations are aimed at utilizing this knowledge to minimise the complications associated with fibrosis, while maintaining adequate rates of ultrafiltration across the peritoneal membrane and preservation of patient urinary volumes. We discuss the development of a new generation of reduced-glucose PD solutions that employ a variety of osmotically active constituents and highlight the biochemical rationale underlying optimization of oxidative metabolism within the peritoneal membrane. They are aimed at achieving optimal clinical outcomes and improving the whole-body metabolic profile of patients, particularly those who are glucose-intolerant, insulin-resistant, or diabetic, and for whom daily exposure to high doses of glucose is contraindicated
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