1,721,221 research outputs found
Deviations in Energy Sensing Predict Long-term Weight Change in Overweight Native Americans
Full text linkBackground/Objecrives: Energy expenditure (EE), as reflective of body energy demand, has been proposed to be the key driver of food intake, possibly influencing weight change in humans. Variation in this energy-sensing link (overeating relative to weight-maintaining energy requirements) may lead to weight gain over time.
Subjects/Methods: Sixty-one overweight otherwise healthy Native Americans (age: 34.0 +/- 7.9 years, body fat: 39.7 +/- 9.5%, 36 males) were admitted to our clinical research unit for measurements of body composition by dual-energy X-ray absorptiometry, and 24-h EE and respiratory quotient (RQ) in a whole-room indirect calorimeter during energy balance and weight stability. Following this, ad libitum food intake was assessed for three days using computerized vending machines. Body weight change under unrestricted free-living conditions was assessed at an outpatient follow-up visit (median follow-up time = 1.7 years).
Results: Total ad libitum food intake (3-day average) was positively associated with 24-h EE (r = 0.44, p < 0.001). RQ (r = 0.34, p = 0.007), and fat free mass (r = 0.38, p = 0.002). A relatively greater food intake after accounting for 24-h EE, but not for RQ (p = 030) or for fat free mass (p = 0.23) nor total food intake (p = 0.16), predicted weight gain at the outpatient follow-up visit (r = 026, p = 0.04), such that overeating 100 Kcal/d above the food intake predicted by 24-h EE at baseline was associated with an average weight gain of 0.22 Kg over the follow-up period (95% CI: 0.01 to 0.42 Kg). This was due to relatively greater dietary fat intake (r = 0.32, p = 0.01), but not carbohydrate (p = 0.27) or protein (p = 0.06) intake.
Conclusion: The individual propensity to overeating, particularly fat, in excess of the weight-maintaining energy requirements can be assessed and predicts long-term weight gain, suggesting that variation in energy sensing may influence appetite by favoring overeating thus promoting obesity development
Decline in the Acute Insulin Response in Relationship to Plasma Glucose Concentrations
No full textBACKGROUND:
To investigate (1) whether the decline in acute insulin response (AIR) precedes or coincides with defined glucose regulation categories and whether acute insulin response decline varies by race and adiposity, (2) linearity of the relationship between acute insulin response and increasing plasma glucose concentrations, (3) longitudinal changes in acute insulin response accounting for changes in insulin action across categories of glucose tolerance.
METHODS:
Clinical cross-sectional and longitudinal study of nondiabetic subjects. Inpatient assessment of oral glucose tolerance (2-h PG, fasting PG), and acute insulin response (intravenous glucose tolerance test) in 326 and 84 Native Americans of full and ≤6/8th Southwestern heritage, respectively, and 115 Whites. Linearity of acute insulin response vs plasma glucose concentrations investigated using spline analyses. Follow-up (average = 2.07 years) glucose tolerance, acute insulin response, and insulin action (hyperinsulinemic-euglycemic clamp) assessed in 230 full Native Americans.
RESULTS:
In certain groups, the relationship between acute insulin response and increasing plasma glucose levels was non-linear. In all groups, acute insulin response decline preceded the cut-offs for traditional glucose regulation categories, although the timing with respect to increasing plasma glucose varied by race and adiposity. Longitudinal data indicated that improvement in insulin action is the key factor to preserve insulin secretion, underlying the reversion of glucose tolerance in prediabetic individuals.
CONCLUSIONS:
With worsening insulin action, the decline in insulin secretion occurred prior to current diagnostic guidelines for impaired glucose regulation. However, the relationship between acute insulin response and increasing plasma glucose varies and was not always non-linear. Understanding the dynamics of this relationship may determine when to initiate preventive pharmacotherapy directed at the preservation of β-cell failure
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
Peripheral Endocannabinoids Associated with Energy Expenditure in Native Americans of Southwestern Heritage
No full textContext: The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG), as well as the related acylethanolamide oleoylethanolamide (OEA), have been implicated in energy expenditure (EE) regulation and metabolic diseases. Muscle (fat-free mass) and fat (fat mass) are metabolically active compartments and main determinants of EE. Objective: To assess whether human muscle, adipose, and plasma endocannabinoids correlate with EE. Design: Muscle, adipose, and plasma AEA, 2-AG, and OEA concentrations were measured via liquid chromatography-mass spectrometry. EE was assessed by indirect whole-room calorimetry. Setting: Clinical trial. Participants: Obese/overweight Native Americans of full (n = 35) and at least half (n = 21) Southwestern heritage. Main Outcome Measures: Twenty-four-hour EE, sleeping EE (SLEEP), resting EE (REE), respiratory quotient (RQ), and macronutrient oxidation. Results: In full Natives, muscle AEA concentration correlated with SLEEP (r = -0.65, P = 0.004) and REE (r = -0.53, P = 0.02). Muscle 2-AG was associated with SLEEP (r = -0.75, P = 0.0003). Adipose OEA concentration correlated with RQ (r = -0.47, P = 0.04) and lipid oxidation (r = 0.51, P = 0.03). Plasma OEA concentration was associated with SLEEP (r = -0.52, P = 0.04). After adjustment for major determinants, these lipids explained nearly 20% of the additional variance of the respective measure. Similarly, in Native Americans of at least half Southwestern heritage, investigated lipids correlated with EE measures. Conclusion: Endocannabinoids in metabolically relevant peripheral tissues explained a large part of EE variation and may be involved in regulating EE. Dysregulation of peripheral endocannabinoids may predispose people to metabolic diseases via an effect on EE and lipid oxidation
Response of skeletal muscle UCP2-expression during metabolic adaptation to caloric restriction
No full textSpendthrift vs. thrifty individuals expend more energy and experience greater weight loss during caloric restriction (CR). Adaptive mechanisms in skeletal muscle, adipose tissue, and on hormone level modulate energy expenditure (EE) during weight loss. Metabolic mechanisms underlying the variability in EE during CR are unclear. The present study explored whether during long-term CR (i) gene expression changes in skeletal muscle and adipose tissue relate with the individual EE response and weight loss, and (ii) altered catecholamine and FGF21-concentrations are associated with measures of metabolic adaptation
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