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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to its established role in the immune system, tumour necrosis factor alpha (TNFalpha) exerts complex regulatory actions on adipose tissue. TNFalpha is produced in and secreted by the adipocyte and thus is in a position to exert a paracrine and/or autocrine role within adipose tissue. TNFalpha affects many aspects of adipocyte function, from adipocyte development to lipid metabolism. Bringing together all of these diverse actions, TNFalpha appears to play a general role in reducing adipose tissue mass. Dysregulation of TNFalpha production and/or action could be one facet in the development of cachexia and obesity, as well as associated metabolic disorders such as insulin resistance.
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PMID:Tumour necrosis factor alpha: a key regulator of adipose tissue mass. 1277 14

Melatonin (MLT), the circadian neurohormone secreted by the pineal gland in mammals during darkness, eicosapentanoic acid (EPA), and conjugated linoleic acid (CLA) have established regulatory roles in cancer growth. Investigations in our laboratory have indicated that these agents inhibit fatty acid (FA) transport by tumors and several sub-types of white adipose tissue via inhibitory G protein-coupled receptor mechanisms. Skeletal muscle constitutes over 45% of human body mass and plays an important role in cancer cachexia and obesity-related diseases. Since fatty acid oxidation is a major source of energy for this tissue, we tested the hypothesis that physiologic MLT levels, EPA, or CLA injected intravenously, inhibit FA uptake in rat skeletal muscle in vivo. We used a surgical technique for catheterizing the femoral vein in rats that allows rapid blood collection from the entire hind limb, while ensuring continuous blood flow to the tissue. Blood acid/gas tensions and hematocrit were monitored and remained constant during the course of each experiment. The MLT, EPA, and CLA inhibited FA uptake by the tissue and lowered cAMP values. Glucose uptake and glycerol production in the hind limb were not affected. These investigations suggest a novel role for MLT, omega-3 FAs, and CLA in the regulation of FA transport and fat metabolism in skeletal muscle.
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PMID:Physiologic melatonin concentration, omega-3 fatty acids, and conjugated linoleic acid inhibit fatty acid transport in rodent hind limb skeletal muscle in vivo. 1278 53

There has been great interest in melanocortin (MC) receptors as targets for the design of novel therapeutics to treat disorders of body weight, such as obesity and cachexia. Both genetic and pharmacological evidence points toward central MC4 receptors as the principal target. Using highly selective peptide tools for the MC4 receptor, which have become available recently, we have provided pharmacological confirmation that central MC4 receptors are the prime mediators of the anorexic and orexigenic effects reported for melanocortin agonists and antagonists, respectively. The current progress with receptor-selective small molecule agonist and antagonist drugs should enable the therapeutic potential of MC4 receptor activation and inhibition to be assessed in the clinic in the near future.
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PMID:Body weight regulation by selective MC4 receptor agonists and antagonists. 1285 4

Four years ago Kojima and coworkers discovered ghrelin. Within this short lifespan ghrelin has become one of the "hottest topics" in metabolic research, and today more than 300 papers have emerged (PubMed search). The huge interest in ghrelin is partly due to its involvement in appetite regulation. Over-nutrition, obesity and type 2 diabetes are major burdens of health services in all Western countries, and the discovery of ghrelin opens for the development of antagonists that may make it possible to control appetite and food intake. At the other end of the nutritional scale, ghrelin agonists may be used in cachexia in e.g. anorexia nervosa and cancer. Thus, the potential clinical value of ghrelin research appears to be enormous. At the time of writing several in-house as well as commercial ghrelin assays have been developed. However, we still need to come to a consensus on measurement of circulating ghrelin levels. Up till now, blood ghrelin has been estimated by use of serum as well as various types of plasma, with or without extraction prior to assay. This may affect both results and conclusions. In the present paper we shall review the current literature on ghrelin, with special focus on measurements in human blood specimens.
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PMID:Assessment of ghrelin. 1287 66

Over the past decade, there has been a tremendous increase in the understanding of the molecular and neural mechanisms that control food intake and body weight. Yet eating disorders and cachexia are still common, and obesity cases are rising at alarming rates. Thus, despite recent progress, an increased understanding of the molecular and neural substrates that control body weight homeostasis is a major public health goal. In this review, we discuss the mechanisms by which metabolic signals interact with key behavioral, neuroendocrine, and autonomic regulatory regions of the central nervous system. Additionally, we offer a model in which hormones such as leptin and ghrelin interact with similar central nervous system circuits and engage them in such a way as to maintain an appropriate and tight regulation of body weight and food intake. Our model predicts that overstimulation or understimulation of these central pathways can result in obesity, anorexia, or cachexia.
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PMID:Minireview: From anorexia to obesity--the yin and yang of body weight control. 1293 44

Macrophages are part of the immunity defense mechanism via oxidative burst and phagocytosis. They are also involved in tissue remodeling via cytokine secretion and apoptotic body clearance. Previously, we demonstrated that adipose cells and macrophages share some of their features and functions. Our aim was to further test this hypothesis in humans. We first demonstrated that human preadipocytes exhibit phagocytosis of yeast, this effect being specific compared to another fibroblastic cell type, the skin fibroblast. Furthermore, as in rodents, human preadipocytes exhibit anti-microbial activity. Finally, for the first time, it was shown that these cells were able to phagocyte apoptotic lymphocytes. Altogether, these data suggest an active involvement of fat cells in host defense and tissue remodeling, which might play an important role at the level of the whole organism due to the large amount of adipose tissue. This gives support for some observations linking obesity or cachexia to immunological disorders.
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PMID:Human adipose cells as candidates in defense and tissue remodeling phenomena. 1296 17

Ghrelin is a 28-amino-acid peptide predominantly produced by the stomach, while substantially lower amounts derive from other tissues including the pancreas. It is a natural ligand of the GH secretagogue (GHS) receptor (GHS-R1a) and strongly stimulates GH secretion, but acylation in serine 3 is needed for its activity. Ghrelin also possesses other endocrine and nonendocrine actions reflecting central and peripheral GHS-R distribution including the pancreas. The wide spectrum of ghrelin activities includes orexigenic effect, control of energy expenditure, and peripheral gastroenteropancreatic actions. Circulating ghrelin levels mostly reflect gastric secretion as indicated by evidence that they are reduced by 80% after gastrectomy and even after gastric by-pass surgery. Ghrelin secretion is increased in anorexia and cachexia but reduced in obesity, a notable exception being Prader-Willi syndrome. The negative association between ghrelin secretion and body weight is emphasized by evidence that weight increase and decrease reduces and augments circulating ghrelin levels in anorexia and obesity, respectively, and agrees with the clear negative association between ghrelin and insulin levels. In fact, ghrelin secretion is increased by fasting whereas it is decreased by glucose load as well as during euglycemic clamp but not after arginine or free fatty acid load in normal subjects; in physiological conditions, however, the most remarkable inhibitory input on ghrelin secretion is represented by somatostatin as well as by its natural analog cortistatin that concomitantly reduce beta-cell secretion. This evidence indicates that the endocrine pancreas plays a role in directly or indirectly modulating ghrelin secretion.
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PMID:Ghrelin and the endocrine pancreas. 1461 Feb 95

In this paper the perspective for nutritional modulation of systemic impairment in patients with chronic obstructive pulmonary disease (COPD) is discussed. Progressive weight loss is characterised by disease-specific elevated energy requirements unbalanced by dietary intake. Weight gain per se can be achieved by caloric supplementation while future studies may prove efficacy of amino acid modulation to stimulate protein synthesis and enhance muscle anabolism. Disproportionate muscle wasting resembles the cachexia syndrome as described in other chronic wasting diseases (cancer, chronic heart failure, acquired immunodeficiency syndrome (AIDS)). There is yet no adequate nutritional strategy available to treat cachexia in COPD. Muscle substrate metabolism has hardly been investigated, but the few data available point towards a decreased fat oxidative capacity that may show similarities with the "metabolic syndrome" as described in type II diabetes and obesity and could theoretically benefit from polyunsaturated fatty acid modulation. To adequately target the different therapeutic options, clearly more clinical (intervention) studies are needed in chronic obstructive pulmonary disease patients that are adequately characterised by local and systemic impairment and in which molecular and metabolic markers are linked to functional outcome.
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PMID:Nutritional and metabolic modulation in chronic obstructive pulmonary disease management. 1462 Nov 10

Most obese animal models, whether associated with genetic, diet-induced, or age-related obesity, display pronounced leptin resistance, rendering leptin supplement therapy ineffective in treating obesity. Ciliary neurotrophic factor (CNTF) has been recently used to invoke leptin-like signaling pathways, thereby circumventing leptin resistance. In the current study, we characterize immediate and long-term molecular events in the hypothalamus of rats exposed to the sustained ectopic expression of leptin, CNTF, or leukemia inhibitory factor, another neurocytokine of IL-6 family, all delivered centrally via a viral vector. The respective transgene-encoded ligands induced similar but not identical metabolic responses as assessed by the reduction in body weight gain and changes in food intake. To define molecular mechanisms of weight-reducing and anorexigenic action of cytokines, we have analyzed the gene expression profiles of 1300 brain-specific genes in the hypothalami of normal rats subjected to the prolonged cytokine action for 10 wk. We present evidence that constitutive expression of cytokines in the brain induces changes in gene expression characteristic of chronic inflammation leading to either temporal weight reduction (CNTF) or severe cachexia (leukemia inhibitory factor). Our results convey a cautionary note regarding potential use of the tested cytokines in therapeutic applications.
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PMID:Differential modulation of energy balance by leptin, ciliary neurotrophic factor, and leukemia inhibitory factor gene delivery: microarray deoxyribonucleic acid-chip analysis of gene expression. 1471 13

Loss of adipose tissue in cancer cachexia has been associated with tumour production of a lipid-mobilizing factor (LMF) which has been shown to be homologous with the plasma protein zinc-alpha(2)-glycoprotein (ZAG). The aim of this study was to compare the ability of human ZAG with LMF to stimulate lipolysis in vitro and induce loss of body fat in vivo, and to determine the mechanisms involved. ZAG was purified from human plasma using a combination of Q Sepharose and Superdex 75 chromatography, and was shown to stimulate glycerol release from isolated murine epididymal adipocytes in a dose-dependent manner. The effect was enhanced by the cyclic AMP phosphodiesterase inhibitor Ro20-1724, and attenuated by freeze/thawing and the specific beta3-adrenoreceptor antagonist SR59230A. In vivo ZAG caused highly significant, time-dependent, decreases in body weight without a reduction in food and water intake. Body composition analysis showed that loss of body weight could be attributed entirely to the loss of body fat. Loss of adipose tissue may have been due to the lipolytic effect of ZAG coupled with an increase in energy expenditure, since there was a dose-dependent increase in expression of uncoupling protein-1 (UCP-1) in brown adipose tissue. These results suggest that ZAG may be effective in the treatment of obesity.
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PMID:Induction of lipolysis in vitro and loss of body fat in vivo by zinc-alpha2-glycoprotein. 1498 39


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