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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
Circulating adiponectin levels and cardiovascular risk factors in acromegalic patients
No full textOBJECTIVE: Adiponectin (ApN) is an adipocytokine expressed in human adipose cells with anti-atherogenic and anti-inflammatory properties that plays a role in the pathophysiology of insulin resistance, metabolic syndrome and coronary artery disease. The aim of the study was to evaluate ApN secretion in patients with acromegaly, a chronic disease associated with insulin resistance and increased cardiovascular mortality, and to correlate ApN levels with hormonal, metabolic and cardiovascular parameters. DESIGN AND METHODS: The study included 32 patients with active acromegaly (11 male and 21 female, aged 48+/-11 years, duration of disease: 8+/-6 years, GH: 9.2+/-9.8 microg/l, IGF-I: 80+/-33 nmol/l (means+/-s.d.)) and 38 control subjects sex- and body mass index (BMI)-matched. In all subjects, serum ApN, leptin and ghrelin levels, BMI, waist circumference, insulin resistance (assessed by homeostasis model assessment and the quantitative insulin check index), lipid profile and blood pressure values were evaluated. RESULTS: Acromegalic patients and control subjects had similar ApN levels (9.4+/-3.5 vs 9.5+/-4.0 mg/l, NS), while when considering obese subjects acromegalic patients had ApN levels significantly higher than controls (10.2+/-4 vs 7.5+/-3 mg/l, P<0.05). No significant correlation between ApN and GH/IGF-I levels or duration of disease was found. ApN concentrations negatively correlated with BMI, waist circumference, glucose and diastolic blood pressure and positively with high-density lipoprotein cholesterol and ghrelin in controls, while all these correlations were lost in acromegalic patients. CONCLUSIONS: We provide evidence that, although metabolic and cardiovascular abnormalities are present in most acromegalic patients, in these subjects ApN levels are not reduced and, contrary to what is found in BMI-matched controls, do not correlate with cardiovascular risk factors. These data support the view that atherosclerosis is not the main determinant of cardiovascular mortality in acromegaly and suggest a permissive action of GH and/or IGF-I excess on ApN secretion
Effect of recombinant human growth hormone (GH) replacement on the hypothalamic-pituitary-adrenal axis in adult GH-deficient patients
No full textThe aim of the study was to evaluate the hypothalamuspituitary-adrenal (HPA) axis in patients ( nine males, three females; mean age +/- SEM 51 +/- 2 yr) with adult-onset GH deficiency (GHD) due to surgically treated pituitary tumors with preserved HPA function and without evidence of tumor recurrence before and during recombinant human ( rh) GH replacement therapy (duration 31 +/- 6 months). HPA function was assessed by urinary free cortisol and morning serum cortisol levels as well as cortisol responses to 1 mug ACTH test (n = 7 patients) or insulin tolerance test (n = 5 patients) before and during rhGH therapy, the cut-off for the diagnosis of hypoadrenalism being a cortisol peak less than 18 mug/dl (< 500 nmol/liter) after stimulatory tests. Serum cortisol and urinary free cortisol levels were significantly lower on therapy than before [7.6 +/- 0.8 vs. 11.5 +/- 0.9 mu g/dl (208 +/- 22 vs. 317 +/- 24 nmol/liter), P < 0.01, and 19.6 +/- 2.5 vs. 32.2 +/- 3.2 mug per 24 h (54 +/- 7 vs. 89 +/- 9 nmol per 24 h), P < 0.05, respectively], whereas no change in cortisol-binding globulin levels was observed. Cortisol peak after either ACTH test or insulin tolerance test was lower on rhGH therapy than before [15.9 +/- 1.5 vs. 20.2 +/- 1.1 mu g/dl (437 +/- 43 vs. 557 +/- 31), P = 0.01, and 13.1 +/- 2.6 vs. 20.4 +/- 1.4 mu g/dl (362 +/- 71 vs. 564 +/- 37 nmol/liter), P = 0.03, respectively]. Accordingly, central hypoadrenalism was detected in nine of 11 patients. In conclusion, low GH and IGF-I levels, likely enhancing the conversion of cortisone to cortisol, may mask a condition of central hypoadrenalism. Therefore, the reassessment of HPA function in GHD patients during rhGH therapy is mandatory
Different effects of short- and long-term recombinant hGH administration on ghrelin and adiponectin levels in GH-deficient adults
No full textOBJECTIVE: To evaluate circulating levels of ghrelin and adiponectin (ApN) in GH-deficient (GHD) adults before and after short- and long-term recombinant human GH (rhGH) administration.
PATIENTS AND METHODS: Twenty-three patients were studied. Seventeen subjects (Group A, 12 men, five women) were evaluated at baseline and after 1 year rhGH therapy (dose mean +/- SD: 0.3 +/- 0.1 mg/day) with the assessment of serum IGF-I, ghrelin, ApN, leptin, insulin and glucose levels, percentage of body fat (BF%), HOMA-IR and QUICKI. Seventeen age-, sex- and body mass index (BMI)-matched healthy subjects were recruited for comparisons. Six patients (Group B, three men, three women) underwent IGF-I generation test (rhGH 0.025 mg/kg/day for 7 days), blood sampled at baseline and on day 8 for determination of IGF-I, ghrelin and ApN levels.
RESULTS: Group A: at baseline GHD patients showed low IGF-I levels and BF% significantly higher than controls (31.4 +/- 2.5 vs. 26.4 +/- 1.3, P < 0.05). Glucose, insulin, leptin, tryglicerides, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels, as well as HOMA-IR and QUICKI values were similar in the two series, while total cholesterol levels were higher in GHD. In GHD, ghrelin levels were significantly lower than in controls (193.9 +/- 27.1 vs. 298.1 +/- 32.5 pmol/l, respectively, P = 0.02), while ApN levels were similar (10.2 +/- 1.1 and 9 +/- 1 mg/l, respectively, P = ns). After 1 year of rhGH therapy, BF%, BMI, serum total and LDL cholesterol significantly decreased, serum leptin levels showed a trend to decrease, while HOMA-IR and QUICKI did not change. Ghrelin and ApN levels significantly increased from 193.9 +/- 27.1 to 232.4 +/- 26.3 pmol/l (P < 0.01) and from 8.6 +/- 0.8 to 10.3 +/- 1.1 mg/l (P < 0.05), respectively. In group B, the expected increase in IGF-I levels was associated with a significant decrease in ghrelin levels, while ApN did not change.
CONCLUSION: GHD patients showed serum ghrelin lower than controls, probably due to the higher BF%. No difference in ApN was observed. Ghrelin and ApN increments induced by long-term treatment may be related to the significant BMI and BF% reduction that is the predominant metabolic effect of rhGH therapy. Conversely, the decrease in ghrelin levels observed after short-term rhGH administration may be consistent with an inhibitory feedback of GH and/or IGF-I on ghrelin release
Adiponectin expression in human fetal tissues during mid- and late gestation
No full textAdiponectin (ApN), an adipocytokine expressed in adipocytes with antidiabetic and antiatherogenic actions, has been detected in cord blood, suggesting a putative role in intrauterine fetal development. The aim of this study was to confirm the presence of ApN in the fetal circulation and directly investigate ApN expression in fetal tissues. The study showed high ApN levels in umbilical venous blood from fetuses [n = 44; 31.2 +/- 14.1 (sd) mg/liter in umbilical vs. 8.4 +/- 4.0 in maternal circulation (P < 0.0001)] that positively correlated with gestational age. By using RT-PCR, Western blotting, and immunohistochemistry, ApN was detected in several fetal tissues at mid- and late gestation (from 14 to 36 wk) but not in the placenta. ApN was expressed in tissues of mesodermic origin, i.e. brown and white adipocytes, skeletal muscle fibers of diaphragm and iliopsoas, smooth muscle cells of small intestine and arterial walls, perineurium and renal capsule, and tissues of ectodermal origin, i.e. epidermis and ocular lens. The distribution of ApN expression in nonadipose tissues showed a general decline during the progression of gestation. The unexpected pattern of ApN expression in the human fetus may account for the high ApN levels in cord blood and predicts novel roles for ApN during fetal development
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
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