116 research outputs found
Influence of Hyperinsulinemia and Insulin Resistance on In Vivo beta-Cell Function Their Role in Human beta-Cell Dysfunction
No full textOBJECTIVE-Recent work has shown that insulin stimulates its own secretion in insulin-sensitive humans, suggesting that insulin resistance in the beta-cell could cause beta-cell dysfunction. We have tested whether insulin exposure and insulin sensitivity modulate beta-cell function in subjects with normal glucose tolerance (NGT) and whether they contribute to dysglycemia in impaired glucose regulation (IGR).
RESEARCH DESIGN AND METHODS-Insulin sensitivity (by euglycemic clamp), insulin-induced secretory response at iso-glycemia (HSR) (as C-peptide percent change from basal during the clamp), glucose-induced secretory response (GISR) to an intravenous glucose bolus, and beta-cell glucose sensitivity (beta-GS) (by oral glucose tolerance test [OGTT] modeling) were measured in 1,151 NGT and 163 IGR subjects from the RISC (Relationship between Insulin Sensitivity and Cardiovascular Disease) study.
RESULTS-In NGT, IISR was related to both insulin sensitivity and antecedent insulin exposure; GISR was related to insulin exposure. IISR was positively, if weakly, related to beta-GS (r = 0.16, P < 0.0001). Both IISR (-23 [39] vs. -9 [2]%, median [interquartile range], P < 0.03) and beta-GS (69 [47] vs. 118 [83] pmol . min(-1) . m(-2) . mmol(-1) . L, P < 0.0001) were decreased in IGR compared with NGT. Insulin sensitivity and beta-GS were the major determinants of mean OGTT glucose in both NGT and IGR, with a minor role for IISR. In a multivariate logistic model, IGR was predicted by beta-GS (odds ratio 4.84 [95% CI 2.89-8.09]) and insulin sensitivity (3.06 [2.19-4.27]) but not by IISR (1.11 [0.77-1.611).
CONCLUSIONS-Pre-exposure to physiological hyperinsulinemia stimulates insulin secretion to a degree that depends on insulin sensitivity. However, this phenomenon has limited impact on beta-cell dysfunction and dysglycemia. Diabetes 60:3141-3147, 201
Seeking temporal refugia to heat stress: Increasing nocturnal activity despite predation risk
No full textFlexibility in activity timing may enable organisms to quickly adapt to environmental changes. Under global warming, diurnally adapted endotherms may achieve a better energy balance by shifting their activity towards cooler nocturnal hours. However, this shift may expose animals to new or increased environmental challenges (e.g. increased predation risk, reduced foraging efficiency). We analysed a large dataset of activity data from 47 ibex (Capra ibex) in two protected areas, characterized by varying levels of predation risk (presence versus absence of the wolf-Canis lupus). We found that ibex increased nocturnal activity following warmer days and during brighter nights. Despite the considerable sexual dimorphism typical of this species and the consequent different predation-risk perception, males and females demonstrated consistent responses to heat in both predator-present and predator-absent areas. This supports the hypothesis that shifting activity towards nighttime may be a common strategy adopted by diurnal endotherms in response to global warming. As nowadays different pressures are pushing mammals towards nocturnality, our findings emphasize the urgent need to integrate knowledge of temporal behavioural modifications into management and conservation planning
Insulin Sensitivity and beta-Cell Function in the Offspring of Type 2 Diabetic Patients: Impact of Line of Inheritance
No full textContext: What defects in glucose metabolism are present in offspring of type 2 diabetic patients (FHD(+) with a positive family history of diabetes) and to what extent they depend on line of inheritance are uncertain. Objective: The objective of this study was to assess clinical phenotype, insulin sensitivity, and beta-cell function in FHD(+) by line of inheritance. Subjects: The subjects included 1221 nondiabetic men and women aged 30-60 yr, of whom 343 were FHD(+), who participated to the Relationship between Insulin Sensitivity and Cardiovascular Disease Investigators study, a multicenter European collaboration. Main Outcome Measures: The main outcome measures included the following: insulin sensitivity by the euglycemic clamp; total insulin secretion, beta-cell glucose sensitivity, rate sensitivity, and potentiation by C-peptide deconvolution and oral glucose tolerance test modeling; and acute insulin response to i.v. glucose. Results: Older age, increased adiposity, and dyslipidemia were the dominant features of FHD(+) clinical phenotype. FHD(+) subjects had a 13% reduction in insulin sensitivity [95% confidence interval (CI) of 6,19], which in males was more pronounced (17%, CI: 5,24 vs. 10%, CI: 2,20) and influenced by maternal inheritance (21%, CI: 5,38 vs. 14%, CI: 0,28 paternal). After adjusting for confounders, beta-cell glucose sensitivity and rate sensitivity were reduced by 13% (CI: 3,20) and 18% (CI: 5,35), respectively (P < 0.01 for both); the former defect was more severe with maternal (16%, CI: 4,26) than paternal (9%, CI: -2,22) transmission. Independently of line of inheritance, both fasting and total oral glucose tolerance test insulin secretion were increased in proportion to the insulin resistance, whereas acute insulin response and rate sensitivity were not. Conclusions: Diabetic inheritance is expressed as a characteristic clinical phenotype associated with defects in insulin sensitivity and beta-cell glucose sensitivity, which are accentuated along maternal inheritance. beta-Cell rate sensitivity is reduced and beta-cell dynamic responses to insulin resistance are lost independently of the line of inheritance. (J Clin Endocrinol Metab 95: 4703-4711, 2010
Impact of family history on relation between insulin resistance, LDL cholesterol and carotid IMT in healthy adults.
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If you can use poster or playbill. Art of postering
No full textW tekście omówiono niektóre akcydensowe formy komunikowania wizualnego stosowanego obecnie zwłaszcza w tzw. public relations firm, osób i instytucji. W kontekście możliwości wykorzystania syntetycznych form przekazywania komunikatu
słowno-obrazkowego w edukacji przyrodniczo-leśnej szczególną rolę przypisuje się plakatowi i jego akademickiej odmianie – posterowi. Obie formy są nieodłącznym elementem każdej ekspozycji. Autor przypomina podstawową terminologię związaną z tego typu akcydensami oraz prezentuje niektóre praktyczne realizacje, które miały miejsce w CEPL w Rogowie.The author elaborates about the basic accessory forms of visual communication used nowadays especially in public relation of companies, institutions and people. In context of possibilities to use synthetic forms of transferring the audio-visual
message in forest education, the special role is played by the poster and its academic version. Both forms are inevitable element of every exhibition. The author reminds the basic terminology connected with forms of this kind and presents some of the realizations that took place in Center for Nature and Forest Education in Rogow
At any Level of Adiposity, Relatively Elevated Leptin Concentrations Are Associated With Decreased Insulin Sensitivity
No full textCONTEXT: The impact of obesity on glucose homeostasis has high interindividual variability, which may be partially explained by different adipokine concentrations. Leptin regulates energy balance and metabolism, and although its plasma levels are proportional to fat mass, they vary significantly across individuals with the same level of adiposity. OBJECTIVE: We tested whether glucose homeostasis differs in subjects with similar degrees of adiposity but different leptin levels. METHODS: We analyzed 1290 healthy adults from the Relationship Between Insulin Sensitivity and Cardiovascular Disease study cohort (30-60 years; male/female, 577/713; body mass index [BMI], 25 ± 3 kg/m2) characterized for body composition and metabolic variables with a 75-g oral glucose tolerance test, euglycemic-hyperinsulinemic clamp, β-cell function, and lipidomics. RESULTS: Individuals were divided into relatively high and low leptin (RHL and RLL) if they were above or below the sex-specific leptin-fat mass (%) regression. Despite similar glucose tolerance, RHL showed markedly higher fasting and oral glucose tolerance test insulin concentration (+30% and +29%, respectively; P < .0001) and secretion (+17% and +11%, respectively; P < .0001). Regardless of BMI, RHL individuals had lower whole-body (-17-23%, P < .0001) and adipose tissue insulin sensitivity (-24%, P < .0001) compared with RLL. Notably, lean RHL individuals showed similar insulin sensitivity and β-cell function to RLL individuals with overweight/obesity. CONCLUSION: Subjects with leptin levels that are inappropriately elevated for their fat mass show whole-body/adipose tissue insulin resistance and hyperinsulinemia, regardless of BMI
Alteration in Postprandial Hepatic Glycogen Metabolism in Type 2 Diabetes
No full textDecreased skeletal muscle glucose disposal and increased endogenous glucose production (EGP) contribute to postprandial hyperglycemia in type 2 diabetes, but the contribution of hepatic glycogen metabolism remains uncertain. Hepatic glycogen metabolism and EGP were monitored in type 2 diabetic patients and nondiabetic volunteer control subjects (CON) after mixed meal ingestion and during hyperglycemic-hyperinsulinemic-somatostatin clamps applying 13C nuclear magnetic resonance spectroscopy (NMRS) and variable infusion dual-tracer technique. Hepatocellular lipid (HCL) content was quantified by 1H NMRS. Before dinner, hepatic glycogen was lower in type 2 diabetic patients (227 ± 6 vs. CON: 275 ± 10 mmol/l liver, P < 0.001). After meal ingestion, net synthetic rates were 0.76 ± 0.16 (type 2 diabetic patients) and 1.36 ± 0.15 mg · kg−1 · min−1 (CON, P < 0.02), resulting in peak concentrations of 283 ± 15 and 360 ± 11 mmol/l liver. Postprandial rates of EGP were ∼0.3 mg · kg−1 · min−1 (30–170 min; P < 0.05 vs. CON) higher in type 2 diabetic patients. Under clamp conditions, type 2 diabetic patients featured ∼54% lower (P < 0.03) net hepatic glycogen synthesis and ∼0.5 mg · kg−1 · min−1 higher (P < 0.02) EGP. Hepatic glucose storage negatively correlated with HCL content (R = −0.602, P < 0.05). Type 2 diabetic patients exhibit 1) reduction of postprandial hepatic glycogen synthesis, 2) temporarily impaired suppression of EGP, and 3) no normalization of these defects by controlled hyperglycemic hyperinsulinemia. Thus, impaired insulin sensitivity and/or chronic glucolipotoxicity in addition to the effects of an altered insulin-to-glucagon ratio or increased free fatty acids accounts for defective hepatic glycogen metabolism in type 2 diabetic patients
Influence of migratory ungulate management on competitive interactions with resident species in a protected area
No full textMigratory animals can represent links between protected and unprotected parts of their home ranges. Management of such species outside a conservation area can influence species interactions inside the protected zone. This may result in unintended effects on populations of conservation concern even if they spend their entire life cycle within the protected area. We examined interspecific interactions between three species of large herbivores in the absence of mammalian predators in the Swiss National Park, and assessed whether the population size of the migratory red deer (Cervus elaphus) that is harvested outside the park in autumn and winter affected the two resident species, chamois (Rupicapra rupicapra) and ibex (Capra ibex). Dietary overlap was high between the three species while they co-occurred in the park, suggesting potential for interspecific resource competition. Particularly the habitat use of chamois was affected by red deer population size, with decreased use of meadows and forest with increasing red deer numbers, and increased use of areas covered by scree. Ibex habitat use was affected by the population sizes of all three species, but effects differed between species and season. Moreover, horn growth in young chamois and the population growth rate of ibex were negatively related to red deer numbers. The results suggest that high population size of red deer negatively affects ibex and chamois through the migratory behavior of red deer between protected and non-protected areas. Effective management of a migratory ungulate species outside the protected part of its range, taking account of its ecology and natural behavior, can thus have positive effects on populations within a protected area by alleviating interspecific competition. However, this requires co-operation between policy makers and hunters, acceptance by local people, as well as flexibility to deviate from traditional management regimes such as supplementary feeding to tie animals to certain areas.publishedVersion© 2015 Anderwald et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/3.0
Diel occurrence of characteristic acoustic emission in feeding striped dolphins (Stenella coeruleoalba).
No full textThe paper describes and acoustic behavior of striped dolphin that is made mainly at night in relation with feeding activities. It has been discovered by analyzing recordings made 24/34h with towed arrays of hydrophones
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