Showing papers in "American Journal of Physiology-endocrinology and Metabolism in 2005"
TL;DR: MRS provides a sensitive, quantitative, noninvasive method to measure HTGC and, when applied to a large urban US population, revealed a strikingly high prevalence of hepatic steatosis.
Abstract: Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), the criteria used to diagnose the disorder remain poorly defined. Localized proton magnetic resonance spectroscopy (MR...
1,457 citations
TL;DR: The data suggest that the cardiac hypertrophy seen in VDRKO mice is a consequence of activation of both the systemic and cardiac RAS and support the notion that 1,25-dihydroxyvitamin D(3) regulates cardiac functions, at least in part, through the RAS.
Abstract: Our recent studies suggest that 1,25-dihydroxyvitamin D3 functions as an endocrine suppressor of renin biosynthesis. Genetic disruption of the vitamin D receptor (VDR) results in overstimulation of...
537 citations
TL;DR: Evidence is presented that insulin, acting as an anabolic agent in bone, can preserve and increase bone density and bone strength, presumably through direct and/or indirect effects on bone formation.
Abstract: Diabetic osteoporosis is increasingly recognized as a significant comorbidity of type 1 diabetes mellitus. In contrast, type 2 diabetes mellitus is more commonly associated with modest increases in bone mineral density for age. Despite this dichotomy, clinical, in vivo, and in vitro data uniformly support the concept that new bone formation as well as bone microarchitectural integrity are altered in the diabetic state, leading to an increased risk for fragility fracture and inadequate bone regeneration following injury. In this review, we examine the contribution that insulin, as a potential anabolic agent in bone, may make to the pathophysiology of diabetic bone disease. Specifically, we have assimilated human and animal data examining the effects of endogenous insulin production, exogenous insulin administration, insulin sensitivity, and insulin signaling on bone. In so doing, we present evidence that insulin, acting as an anabolic agent in bone, can preserve and increase bone density and bone strength, presumably through direct and/or indirect effects on bone formation.
443 citations
TL;DR: A role for PPARgamma2 as an inducer of steatosis in hepatocytes is proposed and it is suggested that this phenomenon occurs through an induction of pathways regulating de novo lipid synthesis.
Abstract: Peroxisome proliferator-activated receptor-gamma (PPARgamma) is considered to be one of the master regulators of adipocyte differentiation. PPARgamma2 is abundantly expressed in mature adipocytes and is elevated in the livers of animals that develop fatty livers. The aim of this study was to determine the ability of PPARgamma2 to induce lipid accumulation in hepatocytes and to delineate molecular mechanisms driving this process. The hepatic cell line AML-12 was used to generate a cell line stably expressing PPARgamma2. Oil Red O staining revealed that PPARgamma2 induces lipid accumulation in hepatocytes. This phenotype is accompanied by a selective upregulation of several adipogenic and lipogenic genes including adipose differentiation-related protein (ADRP), adipocyte fatty acid-binding protein 4, sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase, genes whose expression levels are known to increase in steatotic livers of ob/ob mice. Furthermore, the PPARgamma2-regulated induction of both SREBP-1 and FAS parallels an increase in de novo triacylglycerol synthesis in hepatocytes. Triacylglycerol synthesis and lipid accumulation are further enhanced by culturing hepatocytes with troglitazone in the absence of exogenous lipids. These results correspond with an increase in the lipid droplet protein, ADRP, and the data demonstrate that ADRP functions to coat lipid droplets in hepatocytes as observed by confocal microscopy. Taken together, these observations propose a role for PPARgamma2 as an inducer of steatosis in hepatocytes and suggest that this phenomenon occurs through an induction of pathways regulating de novo lipid synthesis.
332 citations
TL;DR: It is concluded that coingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance compared with the intake of carbohydrate only.
Abstract: The present study was designed to determine postexercise muscle protein synthesis and whole body protein balance following the combined ingestion of carbohydrate with or without protein and/or free leucine. Eight male subjects were randomly assigned to three trials in which they consumed drinks containing either carbohydrate (CHO), carbohydrate and protein (CHO+PRO), or carbohydrate, protein, and free leucine (CHO+PRO+Leu) following 45 min of resistance exercise. A primed, continuous infusion of L-[ring-13C6]phenylalanine was applied, with blood samples and muscle biopsies collected to assess fractional synthetic rate (FSR) in the vastus lateralis muscle as well as whole body protein turnover during 6 h of postexercise recovery. Plasma insulin response was higher in the CHO+PRO+Leu compared with the CHO and CHO+PRO trials (+240 +/- 19% and +77 +/- 11%, respectively, P < 0.05). Whole body protein breakdown rates were lower, and whole body protein synthesis rates were higher, in the CHO+PRO and CHO+PRO+Leu trials compared with the CHO trial (P < 0.05). Addition of leucine in the CHO+PRO+Leu trial resulted in a lower protein oxidation rate compared with the CHO+PRO trial. Protein balance was negative during recovery in the CHO trial but positive in the CHO+PRO and CHO+PRO+Leu trials. In the CHO+PRO+Leu trial, whole body net protein balance was significantly greater compared with values observed in the CHO+PRO and CHO trials (P < 0.05). Mixed muscle FSR, measured over a 6-h period of postexercise recovery, was significantly greater in the CHO+PRO+Leu trial compared with the CHO trial (0.095 +/- 0.006 vs. 0.061 +/- 0.008%/h, respectively, P < 0.05), with intermediate values observed in the CHO+PRO trial (0.0820 +/- 0.0104%/h). We conclude that coingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance compared with the intake of carbohydrate only.
325 citations
TL;DR: Increased gene expression promoting lipid accumulation and lipolysis in visceral fat, as well as elevated rate-limiting gluconeogenic enzyme expression in the liver, is consistent with the portal theory.
Abstract: The mechanism by which increased central adiposity causes hepatic insulin resistance is unclear. The “portal hypothesis” implicates increased lipolytic activity in the visceral fat and therefore in...
311 citations
TL;DR: The association of weight loss with increased release of GLP-1 and PYY suggests that procedures that promote gastrointestinal endocrine function can reduce energy intake and support the importance of evaluating the contribution of gastrointestinal hormones to the weight loss seen with bariatric surgery.
Abstract: Bariatric surgeries, such as gastric bypass, result in dramatic and sustained weight loss that is usually attributed to a combination of gastric volume restriction and intestinal malabsorption. However, studies parceling out the contribution of enhanced intestinal stimulation in the absence of these two mechanisms have received little attention. Previous studies have demonstrated that patients who received intestinal bypass or Roux-en-Y surgery have increased release of gastrointestinal hormones. One possible mechanism for this increase is the rapid transit of nutrients into the intestine after eating. To determine whether there is increased secretion of anorectic peptides produced in the distal small intestine when this portion of the gut is given greater exposure to nutrients, we preformed ileal transpositions (IT) in rats. In this procedure, an isolated segment of ileum is transposed to the jejunum, resulting in an intestinal tract of normal length but an alteration in the normal distribution of endocrine cells along the gut. Rats with IT lost more weight (P < 0.05) and consumed less food (P < 0.05) than control rats with intestinal transections and reanastomosis without transposition. Weight loss in the IT rats was not due to malabsorption of nutrients. However, transposition of distal gut to a proximal location caused increased synthesis and release of the anorectic ileal hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY; P < 0.01). The association of weight loss with increased release of GLP-1 and PYY suggests that procedures that promote gastrointestinal endocrine function can reduce energy intake. These findings support the importance of evaluating the contribution of gastrointestinal hormones to the weight loss seen with bariatric surgery.
299 citations
TL;DR: Compared plasma ACTH and corticosterone (Cort) concentrations in pre- and poststress rat blood samples obtained via previously implanted vena cava catheters, tail vein nicks, or clipping the tip off the tail are compared to support either chronic vascular cannulas or sampling from a tail vein.
Abstract: A frequently debated question for studies involving the measurement of stress hormones in rodents is the optimal method for collecting blood with minimal stress to the animal. Some investigators pr...
284 citations
TL;DR: The results indicate that continuous CL treatment induced a transient proinflammatory response that was followed by cellular proliferation among stromal cells and multilocular adipocytes, suggesting involvement of this transcription factor in coordinating the gene program that elevates WAT catabolic activity.
Abstract: Selective agonists of β3-adrenergic receptors (Adrb3) exhibit potent anti-diabetes properties in rodent models when given chronically, yet the mechanisms involved are poorly understood. A salient f...
282 citations
TL;DR: IL-6 seems to be activating lipolysis independently of elevations in GH and/or cortisol and appears to be a potent catalyst for fat oxidation in muscle cells.
Abstract: To determine whether IL-6 increases lipolysis and fat oxidation in patients with type 2 diabetes and/or whether it exerts this effect independently of changes to the hormonal milieu, patients with ...
276 citations
Journal Article•
TL;DR: The hypothesis that myostatin mRNA expression would decrease after resistance loading with a blunted response in older (O) females who have shown minimal hypertrophy after long-term RL is tested, and data clearly demonstrate that RL downregulates hisostatin expression and alters genes key to cell cycle progression.
Abstract: Myostatin inhibits myoblast proliferation and differentiation in developing muscle. Mounting evidence suggests that myostatin also plays a limiting role in growth/repair/regeneration of differentia...
TL;DR: A more rapid rise in MPS after maximal LC could translate into greater protein accretion and muscle hypertrophy during chronic resistance training utilizing maximal LC.
Abstract: We aimed to determine whether there were differences in the extent and time course of skeletal muscle myofibrillar protein synthesis (MPS) and muscle collagen protein synthesis (CPS) in human skele...
TL;DR: Novel effects of ghrelin in the regulation of lean tissue fat distribution and metabolism could contribute to metabolic adaptation to caloric restriction and loss of body fat.
Abstract: Ghrelin is a gastric hormone increased during caloric restriction and fat depletion. A role of ghrelin in the regulation of lipid and energy metabolism is suggested by fat gain independent of chang...
TL;DR: Results demonstrate that OA interacts with GPR40 to increase [Ca(2+)](i) via PLC- and L-type Ca(2+) channel-mediated pathway in rat islet beta-cells, which may be link to insulin release.
Abstract: It has long been thought that long-chain free fatty acids (FFAs) stimulate insulin secretion via mechanisms involving their metabolism in pancreatic β-cells. Recently, it was reported that FFAs fun...
TL;DR: The data suggest that postnatal exposure to altered levels of pituitary hormones leads to development of cellular resistance to oxidative and nonoxidative stressors, which are stable through many rounds of in vitro cell division and could contribute to the remarkable disease resistance of long-lived mutant mice.
Abstract: Previous studies have shown that dermal fibroblast cell lines derived from young adult mice of the long-lived Snell dwarf mutant stock are resistant, in vitro, to the cytotoxic effects of H2O2, cad...
TL;DR: In this article, a postbinding defect in signaling that persists in cultured skin fibroblasts and is associated with constitutive serine phosphorylat(SPH) was found in polycystic ovary syndrome (PCOS).
Abstract: Insulin resistance in polycystic ovary syndrome (PCOS) is due to a postbinding defect in signaling that persists in cultured skin fibroblasts and is associated with constitutive serine phosphorylat...
TL;DR: The "succinate mechanism," which hypothesizes that insulin secretagogues produce both NADPH and mevalonate, and the role of mitochondria in causing oscillations in beta-cell citrate levels is discussed, which may synchronize mitochondrial ATP production and anaplerosis with other cellular oscillations.
Abstract: The importance of mitochondrial biosynthesis in stimulus secretion coupling in the insulin-producing beta-cell probably equals that of ATP production. In glucose-induced insulin secretion, the rate of pyruvate carboxylation is very high and correlates more strongly with the glucose concentration the beta-cell is exposed to (and thus with insulin release) than does pyruvate decarboxylation, which produces acetyl-CoA for metabolism in the citric acid cycle to produce ATP. The carboxylation pathway can increase the levels of citric acid cycle intermediates, and this indicates that anaplerosis, the net synthesis of cycle intermediates, is important for insulin secretion. Increased cycle intermediates will alter mitochondrial processes, and, therefore, the synthesized intermediates must be exported from mitochondria to the cytosol (cataplerosis). This further suggests that these intermediates have roles in signaling insulin secretion. Although evidence is quite good that all physiological fuel secretagogues stimulate insulin secretion via anaplerosis, evidence is just emerging about the possible extramitochondrial roles of exported citric acid cycle intermediates. This article speculates on their potential roles as signaling molecules themselves and as exporters of equivalents of NADPH, acetyl-CoA and malonyl-CoA, as well as alpha-ketoglutarate as a substrate for hydroxylases. We also discuss the "succinate mechanism," which hypothesizes that insulin secretagogues produce both NADPH and mevalonate. Finally, we discuss the role of mitochondria in causing oscillations in beta-cell citrate levels. These parallel oscillations in ATP and NAD(P)H. Oscillations in beta-cell plasma membrane electrical potential, ATP/ADP and NAD(P)/NAD(P)H ratios, and glycolytic flux are known to correlate with pulsatile insulin release. Citrate oscillations might synchronize oscillations of individual mitochondria with one another and mitochondrial oscillations with oscillations in glycolysis and, therefore, with flux of pyruvate into mitochondria. Thus citrate oscillations may synchronize mitochondrial ATP production and anaplerosis with other cellular oscillations.
TL;DR: In this article, the preadipocytes that fat cells develop from exhibit distinct regional characteristics that persist in culture, and human abdominal subcutaneous cultured pre-adipo...
Abstract: Fat depots vary in function and size. The preadipocytes that fat cells develop from exhibit distinct regional characteristics that persist in culture. Human abdominal subcutaneous cultured preadipo...
TL;DR: The expression profile of a series of adipokine genes linked to inflammation has been examined by quantitative PCR during the differentiation of human preadipocytes to adipocytes in primary culture.
Abstract: The expression profile of a series of adipokine genes linked to inflammation has been examined by quantitative PCR during the differentiation of human preadipocytes to adipocytes in primary culture...
TL;DR: It is concluded that leptin requires intact PI3K signaling both to inhibit hypothalamic Npy and Agrp gene expression and activate neurons within the PVN, and that leptin activation of STAT3 is insufficient to inhibit expression of Npy or A Grp in the absence of PI3k signaling.
Abstract: Phosphatidylinositol 3-OH-kinase (PI3K) and STAT3 are signal transduction molecules activated by leptin in brain areas controlling food intake. To investigate their role in leptin-mediated inhibition of hypothalamic neuropeptide Y (Npy) and agouti-related peptide (Agrp) gene expression, male Sprague-Dawley rats (n = 5/group) were either fed ad libitum or subjected to a 52-h fast. At 12-h intervals, the PI3K inhibitor LY-294002 (LY, 1 nmol) or vehicle was injected intracerebroventricularly (ICV) as a pretreatment, followed 1 h later by leptin (3 microg icv) or vehicle. Fasting increased hypothalamic Npy and Agrp mRNA levels (P < 0.05), and ICV leptin administration prevented this increase. As predicted, LY pretreatment blocked this inhibitory effect of leptin, such that Npy and Agrp levels in LY-leptin-treated animals were similar to fasted controls. By comparison, leptin-mediated activation of hypothalamic STAT3 signaling, as measured by induction of both phospho-STAT3 immunohistochemistry and suppressor of cytokine signaling-3 (Socs3) mRNA, was not significantly attenuated by ICV LY pretreatment. Because NPY/AgRP neurons project to the hypothalamic paraventricular nucleus (PVN), we next investigated whether leptin activation of PVN neurons is similarly PI3K dependent. Compared with vehicle, leptin increased the number of c-Fos positive cells within the parvocellular PVN (P = 0.001), and LY pretreatment attenuated this effect by 35% (P = 0.043). We conclude that leptin requires intact PI3K signaling both to inhibit hypothalamic Npy and Agrp gene expression and activate neurons within the PVN. In addition, these data suggest that leptin activation of STAT3 is insufficient to inhibit expression of Npy or Agrp in the absence of PI3K signaling.
TL;DR: Overexpression of GLUT4 in fat reverses whole body insulin resistance in MG4KO mice without restoring glucose transport in muscle, and this effect occurs even though AG4Tg-MG4 KO mice have increased fat mass and low adiponectin and is associated with normalization of elevated resistin levels.
Abstract: Adipose tissue plays an important role in glucose homeostasis and affects insulin sensitivity in other tissues. In obesity and type 2 diabetes, glucose transporter 4 (GLUT4) is downregulated in adipose tissue, and glucose transport is also impaired in muscle. To determine whether overexpression of GLUT4 selectively in adipose tissue could prevent insulin resistance when glucose transport is impaired in muscle, we bred muscle GLUT4 knockout (MG4KO) mice to mice overexpressing GLUT4 in adipose tissue (AG4Tg). Overexpression of GLUT4 in fat not only normalized the fasting hyperglycemia and glucose intolerance in MG4KO mice, but it reduced these parameters to below normal levels. Glucose infusion rate during a euglycemic clamp study was reduced 46% in MG4KO compared with controls and was restored to control levels in AG4Tg-MG4KO. Similarly, insulin action to suppress hepatic glucose production was impaired in MG4KO mice and was restored to control levels in AG4Tg-MG4KO. 2-deoxyglucose uptake during the clamp was increased approximately twofold in white adipose tissue but remained reduced in skeletal muscle of AG4Tg-MG4KO mice. AG4Tg and AG4Tg-MG4KO mice have a slight increase in fat mass, a twofold elevation in serum free fatty acids, an approximately 50% increase in serum leptin, and a 50% decrease in serum adiponectin. In MG4KO mice, serum resistin is increased 34% and GLUT4 overexpression in fat reverses this. Overexpression of GLUT4 in fat also reverses the enhanced clearance of an oral lipid load in MG4KO mice. Thus overexpression of GLUT4 in fat reverses whole body insulin resistance in MG4KO mice without restoring glucose transport in muscle. This effect occurs even though AG4Tg-MG4KO mice have increased fat mass and low adiponectin and is associated with normalization of elevated resistin levels.
TL;DR: Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear hormone receptor that functions as a transcriptional regulator in a variety of tissues.
Abstract: Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear hormone receptor that functions as a transcriptional regulator in a variety of tissues. PPARγ activation, e.g., through binding of ...
TL;DR: Hypoleptinemia in AN is subsequent to decreased basal and pulsatile secretion and nutritionally regulated, and predicts GH and cortisol parameters and with ghrelin predicts GH burst frequency.
Abstract: Ghrelin is an orexigenic peptide and a growth hormone (GH) secretagogue. Secretory dynamics of ghrelin have not been characterized in adolescents with anorexia nervosa (AN). We hypothesized that, compared with healthy adolescents, girls with AN would have increased ghrelin concentrations measured over 12 h of nocturnal sampling from increased basal and pulsatile secretion, and endogenous ghrelin would independently predict GH and cortisol. We examined ghrelin concentration and secretory dynamics in 22 girls with AN and 18 healthy adolescents 12-18 yr old. Associations between ghrelin, various hormones, and measures of insulin resistance were examined. On Cluster analysis, girls with AN had higher ghrelin concentrations than controls, including total area under the curve (AUC) (P = 0.002), nadir (P = 0.0006), and valley levels (P = 0.002). On deconvolution analysis, secretory burst amplitude (P = 0.03) and burst mass (P = 0.04) were higher in AN, resulting in higher pulsatile (P = 0.05) and total ghrelin secretion (P = 0.03). Fasting ghrelin independently predicted GH burst frequency (r = 0.44, P = 0.005). The nutritional markers body mass index and body fat predicted postglucose and valley ghrelin but not fasting levels. Ghrelin parameters were inversely associated with fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, and IGF-I. HOMA-IR was the most significant predictor of most ghrelin parameters. Valley ghrelin independently predicted cortisol burst frequency (52% of variability), and ghrelin parameters independently predicted total triiodothyronine and LH levels. Higher ghrelin concentrations in adolescents with AN are a consequence of increased secretory burst mass and amplitude. The most important predictor of ghrelin concentration is insulin resistance, and ghrelin in turn predicts GH and cortisol burst frequency.
TL;DR: The data suggest that the loss of skeletal muscle mass in this model of disuse appears to be glucocorticoid independent, can be partially rescued with a potent proteasome inhibitor, and is associated with enhanced mRNA expression of multiple factors that contribute to ubiquitin- proteasomesome-dependent degradation and are likely to control the remodeling of immobilized skeletal muscle during atrophy.
Abstract: The hypothesis of the present study was that rats subjected to short-term unilateral hindlimb immobilization would incur skeletal muscle wasting and concomitant alterations in protein synthesis, co...
TL;DR: The melanocyte response to CRH is highly organized along the same functional hierarchy as the HPA axis, demonstrating the fractal nature of the response to stress with similar activation sequence at the single-cell and whole body levels.
Abstract: The response to systemic stress is organized along the hypothalamic-pituitary-adrenal axis (HPA), whereas the response to a peripheral stress (solar radiation) is mediated by epidermal melanocytes (cells of neural crest origin) responsible for the pigmentary reaction. Melanocytes express proopiomelanocortin (POMC), corticotropin-releasing hormone (CRH), and CRH receptor-1 (CRH-R1) and can produce corticosterone. In the present study, incubation of normal epidermal melanocytes with CRH was found to trigger a functional cascade structured hierarchically and arranged along the same algorithm as in the HPA axis: CRH activation of CRH-R1 stimulated cAMP accumulation and increased POMC gene expression and production of ACTH. CRH and ACTH also enhanced production of cortisol and corticosterone, and cortisol production was also stimulated by progesterone. The chemical identity of the cortisol was confirmed by liquid chromatography-mass spectrometry without mass spectrometry-mass spectrometry analyses. POMC gene silencing abolished the stimulatory effect of CRH on corticosteroid synthesis, indicating that this is indirect and mediated via production of ACTH. Thus the melanocyte response to CRH is highly organized along the same functional hierarchy as the HPA axis. This pattern demonstrates the fractal nature of the response to stress with similar activation sequence at the single-cell and whole body levels.
TL;DR: It is concluded that improved skeletal muscle ETC activity following moderate WL and improved aerobic capacity contributes to associated alleviation of insulin resistance and obesity in previously sedentary obese men and women.
Abstract: The current study was undertaken to address responsiveness of skeletal muscle mitochondrial electron transport chain (ETC) activity to weight loss (WL) and exercise in overweight or obese, sedentar...
TL;DR: The data suggest that a decrease in the concentration of malonyl-CoA contributes to the increase in fat oxidation observed at the onset of exercise regardless of muscle glycogen levels, and that the availability of free carnitine may limit fat oxidation during exercise, due to its increased use for acetylcarnitine formation.
Abstract: Intracellular mechanisms regulating fat oxidation were investigated in human skeletal muscle during exercise. Eight young, healthy, moderately trained men performed bicycle exercise (60 min, 65% pe...
TL;DR: It is found that mesoderm-specific transcript (Mest)/paternally expressed gene 1 (Peg1) gene expression was markedly enhanced in white adipose tissue of mice with diet-induced and genetically caused obesity/diabetes but not with streptozotocin-induced diabetes, which does not cause obesity.
Abstract: Obesity is a common and serious metabolic disorder in the developed world that is occasionally accompanied by type II diabetes, atherosclerosis, hypertension, and hyperlipidemia. We have found that mesoderm-specific transcript (Mest)/paternally expressed gene 1 (Peg1) gene expression was markedly enhanced in white adipose tissue of mice with diet-induced and genetically caused obesity/diabetes but not with streptozotocin-induced diabetes, which does not cause obesity. Administration of pioglitazone, a drug for type II diabetes and activator of peroxisome proliferator-activated receptor (PPAR)γ, in obese db/db mice reduced the enhanced expression of Mest mRNA in adipose tissue, concomitant with an increase in body weight and a decrease in the size of adipose cells. Ectopic expression of Mest in 3T3-L1 cells caused increased gene expression of adipose markers such as PPARγ, CCAAT/enhancer binding protein (C/EBP)α, and adipocyte fatty acid binding protein (aP)2. In transgenic mice overexpressing Mest in adip...
TL;DR: It is concluded that abdominal subcutaneous adipose tissue expression of inflammatory cytokines is a potential mechanism linking obesity with its metabolic comorbidities.
Abstract: Adipose tissue is a major source of inflammatory and thrombotic cytokines. This study investigated the relationship of abdominal subcutaneous adipose tissue cytokine gene expression to body composi...