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

The aging process in higher mammals is increasingly being shown to feature a potentially substantial contribution from the longitudinal deterioration of normative stem cell dynamics seen with the passage of time. The precise mechanistic sequence producing this phenomenon is not entirely understood, but recent evidence has strongly implicated intracellular downstream effectors of endocrinologic pathways thought to be engaged by the obese state, specifically the insulin, IGF-1, and leptin signaling pathways. Among the intracellular effectors of these signals, a uniquely potent influence on stem cell dynamics may be attributable to Rho/ROCK, JAK kinase activity and STAT3 activity. In particular, it has already been shown that specific tyrosine kinase activities, such as that seen with Rho kinase, are presently thought to be associated with adverse health outcomes in numerous clinical contexts. Furthermore, the Rho GTPase is thought to be contributing to end-stage renal disease. However, in addition to its contribution to organ system dysfunction, the Rho/ROCK pathway has recently been shown to be activated by insulin and IGF-1, providing a tantalizing connection to nutrition and aging science. The JAK-STAT pathway, in contrast, has long been associated with pro-inflammatory cytokines, but has recently been implicated in leptin signaling as well. Importantly, JAK-STAT signaling has, similarly to Rho/ROCK signaling, been implicated as capable of accelerating stem cell proliferation. The implications of these recent determinations, in light of the recent finding of telomere attrition in humans associated with obesity, are that the intracellular determinants of aging may already be known, and the known common influence of these signaling elements on longitudinal stem cell dynamics is a pronounced induction of proliferation, an elevation that has been linked to the pathologic evolution of longitudinal organ-level dysfunction and the organismal-level physiologic decline seen with the inexorable passage of time. Besides the obvious utility for the management for human age-related dysfunction that investigation of pharmacologic inhibitors of these proteins would provide, interventions such as caloric restriction and possibly intermittent fasting may beneficially influence stem cell proliferation dynamics and reduce intracellular correlates of mitogenic drive. Integrating the findings present in the present body of research may reveal endocrinological states that are compatible with longevity, and will also provide novel insight into the specific proteomic determinants of age-related physiologic decline, ushering in a new epoch of medicine that fosters the management of the "pre-etiopathology" of chronic disease and disability of aging, therefore mitigating the suffering widely thought to be inherent in the latter stages of life.
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PMID:RhoA, Rho kinase, JAK2, and STAT3 may be the intracellular determinants of longevity implicated in the progeric influence of obesity: Insulin, IGF-1, and leptin may all conspire to promote stem cell exhaustion. 1622 46

Obesity is a multi-gene syndrome, expression of which is modulated not only by environmental factors but above all by a number of modified genes interacting with each other. Among candidate genes related to obesity phenotype is ghrelin gene. Ghrelin plays a significant role in feeding regulation and is the strongest stimulator of growth hormone secretion. Ghrelin acts by GHS1a receptor (growth hormone secretagogue receptor). Mutations in preproghrelin and ghrelin gene or ghrelin receptor gene could be responsible for low ghrelin levels observed in obese individuals. Among identificated mutations, two Arg51 Gln and Leu72Met are most often described and change amino-acid sequence of ghrelin (Arg51Gln) and preproghrelin (Leu72Met). Although no direct relationship between Arg51Gln mutation and obesity phenotype was found, it had been shown that carriers of Arg51Gln mutation had significantly decreased plasma ghrelin levels. Furthermore 51Gln allele carriers had higher prevalence of type 2 diabetes mellitus and hypertension than non-carriers. Met 72 carrier status is associated with higher serum IGF-1 levels and seems to be a protective factor against fat accumulation and cardiovascular complications of obesity. No evidence of relationship between ghrelin receptor gene polymorphisms and body mass regulation was found, however, until now there is no study on relationships between these polymorphisms and metabolic complications of obesity. The presence of genetic variants in ghrelin or GHS receptor gene could be responsible for impaired GH secretion in visceral type obesity and development of metabolic syndrome in some of obese subjects. On the other hand, some mutations in preproghrelin gene could be protective against metabolic syndrome.
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PMID:[Preproghrelin gene, ghrelin receptor and metabolic syndrome]. 1622 41

Atypical endometrial hyperplasia has been associated with progression to endometrial cancer, the most common genital malignancy. There are multiple risk factors for endometrial cancer, such as early menarche, exogenous estrogen exposure, obesity and diabetes. Diabetics have a 3-4 fold relative risk of endometrial cancer. Also, several studies have demonstrated an association between insulin resistance and endometrial cancer. There is known the first description of atypical endometrial hyperplasia resistant to progestogen therapy, which was subsequently treated with an insulin-sensitizng agent, metformin. Metformin is a biguanide antihyperglycemic agent used in the treatment of adult-onset diabetes. Unlike the sulfonylureas, metformin does not act primarily by increasing insulin secretion. In contrast, metformin lowers the rate of gluconeogenesis in the presence of insulin. Therefore, it is considered an insulin-sensitizer. Increased insulin sensitivity may improve the metabolic effect of insulin and decrease its mitogenic effect by tissue-specific mechanisms. One explanation for tissue specific differences in insulin binding and action may be through the relative expression of the insulin receptor (IR) isoforms. The IR isoforms IR-A and IR-D differ by 12 amino acid residues, owing to the alternative splicing of exon. The IR-A is predominantly expressed in malignant tissues and may lead to mitogenic effects within the cell. The relative expressions of IR-A and IR-B in normal and malignant endometrial tissue is not known. Besides direct effects on the IR, several additional mechanisms have been proposed for the mitogenic effect of insulin in endometrial cancer. In addition to the possible direct mitogenic effects of insulin through the IR-A, insulin resistance may be associated with alterations in expression of insulin-like growth factors (IGFs) and the IGF binding proteins (IGFBPs) or may inhibit the protective effect of progestagens. Binding sites for IGF-1 and IGF-2 have been confirmed in both normal and malignant endometrium. Binding of IGF-1 is significantly higher in endometrial cancer compared to normal endometrium. In the Ishikawa human endometrial cancer cell line IGF-1 was a more potent mitogen than insulin or IGF-2. Insulin may increase mitogenicity by regulating the expression of IGFBPs. The IGFBPs are a family of proteins that have both proliferative and anti-proliferative effects. While all six high-affinity IGFBPs are expressed in the endometrium, IGFBP-1 is the best characterized. Hyperinsulinemia can decrease IGFBP-1 even in the presence of progesterone, perhaps inhibiting progesterone's protective effects. Interestingly, IGFBP-1 was undetectable or minimally expressed in endometrial cancers. Nestler discussed results of a 6-month treatment of 100 nonebese women with PCOS, which showed a somewhat greater effect of metformin than rosiglitazone and no benefit of administering both agents in combination. Long-term treatment with oral contraceptives decreases endometrial cancer, with a reduction in serum androgens and a decreases in hirsutism and acne, but may worsen insulin resistance and lead to deteriration in glucose tolerance. Insulin sensitizers, on the other hand, should decrease endometrial hyperplasia by inducing regular menses, but may not be as beneficial in improving androgen - related symptoms. Note that the Nurses Health Study (NHS) showed increased risk of diabetes in oral contraceptive users. These considerations may be related to the finding that women who used oral contraceptives have increased risk of myocardial infarction. Thus, in view of the particular increase in CVD risk among women with PCOS, one might be less likely to recommend oral contraceptives, while insulin sensitizers may be of particular benefit, decreasing androgens, improving ovulation and fertility, and reducing the risk of diabetes and CVD. Theoretically, metformin, a treatment which is now widely used to treat infertile women with PCOS, may have a role in preventing endometrial hyperstimulation by lowering insulin concentrations and restoring ovulation. However, the long-term effects of this drug in women with PCOS are not known and more studies are required before suggesting its use for preventing endometrial cancer.
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PMID:[Molecular action of insulin-sensitizing agents]. 1635 Jul 24

The relationship between obesity and prostate cancer is currently a hotly debated topic, but despite the number of publications devoted to the topic, the actual nature of the relationship remains uncertain. Obesity has been shown to have a direct relationship with the incidence of prostate cancer in a number of studies but an equal number of studies have shown no association. The relationship is further obscured with recent findings that obesity in younger obese men may actually be protective against prostate cancer. Confounding factors include the lack of correlation of body mass index (BMI) as a measure of central obesity and the lack of consistency in timing of BMI measurements, i.e. before or after diagnosis and in young or advanced adulthood. Evidence for increased BMI as a risk factor for prostate cancer is unclear, but less ambiguous is the mounting substantiation that obesity is associated with prognostically worse disease, poorer post-surgical outcomes and increased prostate cancer mortality, irregardless of margin status. From a biologic perspective, one can put forth a number of potential mechanisms by which obesity might promote prostate cancer and/or prostate cancer progression including; low levels of testosterone, increased levels of estrogen, co-existing diabetes or metabolic syndrome, increased circulating insulin-growth factor-one (IGF-1), increased levels of leptin, decreased levels of adiponectin and increased dietary saturated fats. Evidence for the association of these factors with prostate cancer are examined herein. The timing of serum measurements is crucial in elucidating whether these factors have causative influence on prostate cancer or rather are produced by the prostate cancer cells and are better understood as markers of disease. The interaction between obesity and prostate cancer is important to clarify because it will have impact on the prevention, prognostication and treatment of prostate cancer. Future study with careful attention to avoid the methodological pitfalls of the past need be accomplished to bear out the nature of the interaction of obesity and prostate cancer.
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PMID:Obesity and prostate cancer. 1667 23

Antipsychotic drugs have been used effectively for the treatment of schizophrenia symptoms, but they are often associated with metabolic side effects such as weight gain and endocrine disruptions. To investigate the possible mechanisms of antipsychotic-induced metabolic effects, we studied the impact of chronic administration of a typical antipsychotic drug (haloperidol) and an atypical antipsychotic (risperidone) to male rats on food intake, body weight, adiposity, and the circulating concentrations of hormones and metabolites that can influence energy homeostasis. Chronic (28days) haloperidol administration had no effect on food intake, weight gain or adiposity in male rats, whereas risperidone treatment resulted in a transient reduction in food intake and significantly reduced body weight gain compared to vehicle-treated control rats. Whereas neither antipsychotic had any effect on serum lipid profiles, glucose tolerance or the circulating concentrations of hormones controlled by the hypothalamo-pituitary-thyroid (free T4), -adrenal (corticosterone), -somatotropic (IGF-1), or -gonadotropic axes (testosterone), haloperidol increased circulating insulin levels and risperidone increased serum glucagon levels. This finding suggests that haloperidol or risperidone induce distinct metabolic effects. Since metabolic disorders such as obesity and type 2 diabetes mellitus represent serious health issues, understanding antipsychotic-induced endocrine and metabolic effects may ultimately allow better control of these side effects.
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PMID:Distinct endocrine effects of chronic haloperidol or risperidone administration in male rats. 1691 86

Obesity is associated with multiple endocrine alterations and changes in the concentration of circulating hormones. However, few studies have explored such alterations in dogs with naturally acquired excess weight. In the present study, we investigated the effect of naturally acquired obesity on cortisol, insulin-like growth factor (IGF)-1 and prolactin secretion in dogs. Thirty-one overweight dogs were enrolled in the trial. Blood samples were collected before and after adrenocorticotrophic hormone (ACTH) injection. Free thyroxine (fT4), cortisol, thyroid-stimulating hormone (TSH), IGF-1, prolactin and fructosamine were assayed. Body weight excess increased significantly with age and neutered dogs were more obese than entire ones. The ACTH stimulation test was within the normal range for 26 of 31 dogs. Prolactinaemia was increased in seven dogs and IGF-1 in six dogs. Twenty dogs had a fructosamine concentration >340 microm. Interestingly, 18 of 31 dogs showed disturbances of thyroid function based on high TSH and/or low fT4 baseline concentration, with 11 dogs showing both. According to these parameters only six of 31 dogs were free of hormonal disturbances. These results revealed the high incidence of such disturbances, especially thyroid dysfunction, in obese, but otherwise apparently healthy dogs. They demonstrate the importance of examining endocrine function during the initial evaluation of obese dogs to avoid failure of any nutritional treatment.
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PMID:Hormonal disturbances associated with obesity in dogs. 1695 91

Extreme loss of skeletal muscle mass (atrophy) occurs in human muscles that are not used. In striking contrast, skeletal muscles do not rapidly waste away in hibernating mammals such as bears, or aestivating frogs, subjected to many months of inactivity and starvation. What factors regulate skeletal muscle mass and what mechanisms protect against muscle atrophy in some species? Severe atrophy also occurs with ageing and there is much clinical interest in reducing such loss of muscle mass and strength (sarcopenia). In the meat industry, a key aim is optimizing the control of skeletal muscle growth and meat quality. The impaired response of muscle to insulin resulting in diabetes, that is a consequence of the metabolic impact of increasing obesity and fat deposition in humans, is also of increasing clinical concern. Intensive research in these fields, combined with mouse models, is reviewed with respect to the molecular control of muscle growth (myogenesis) and atrophy/hypertrophy and fat deposition (adipogenesis) in skeletal muscle, with a focus on IGF-1/insulin signaling.
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PMID:Of bears, frogs, meat, mice and men: complexity of factors affecting skeletal muscle mass and fat. 1699 28

IGF-1 measurement is used for screening of GH deficiency and monitoring of GH therapy in children. However, several commercial immunoassays are currently used and reference values provided by manufacturers are very different. The aim of this study was to compare commercial IGF-1 assays 1) in terms of absolute values and 2) in terms of clinical interpretation of results based on IGF-1 reference values in serum samples from children with GH therapy, with untreated GH deficiency and with obesity. Serum samples of 9 patients were sent frozen to 5 university hospitals using 5 different IGF-1 assays. The inter-laboratory coefficient of variation (CV) was calculated for the 9 samples. For clinical interpretation, results were expressed as SD scores based on reference values provided by manufacturers (and used in these laboratories). The mean inter-laboratory CV (range) for the 9 serum samples was 25.8% (16.7-35.9%). Major variability was noted in the SD-scores between IGF-1 assays for 3 tested serum samples from GH-treated patients with a difference between the lowest and highest SD score of 2.6 up to 3.2. In conclusion, there is a large variability among commercial IGF-1 immunoassays, not only in terms of absolute values, but also in terms of clinical interpretation in pediatric serum samples. There is a need for IGF-1 immunoassay harmonization and for the establishment of adequate reference values.
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PMID:Variability among five different commercial IGF-1 immunoassays in conditions of childhood-onset GH deficiency and GH therapy. 1732 43

Identification of genes and pathways that alter lifespan has allowed for new insights into factors that control the aging process as well as disease. While strong molecular links exist between aging and metabolism, we hypothesize that targeting the mechanisms involved in aging will also give rise to therapeutics that treat other devastating age-related diseases, such as neurodegeneration, cancer, inflammation and cardiovascular disease. Insulin sensitivity, glycemic control and adiposity are not only hallmarks of the major metabolic diseases, type 2 diabetes and obesity, but they also represent significant risk factors for the development of Alzheimer's Disease and cognitive impairment. Insulin/IGF-1 signaling is an important pathway regulating aging and disease in a variety of species, including mammals. Here we describe an important role for the gut-derived peptide ghrelin in upstream signaling through the insulin/IGF-1 pathway and exemplify modulation of ghrelin signaling as an approach to mechanistic treatment of multiple age-related diseases by virtue of its ability to regulate key metabolic functions.
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PMID:Insulin resistance, glycemic control and adiposity: key determinants of healthy lifespan. 1743 Feb 40

Obesity and its related diseases are the leading cause of death in western society, with associated risks of hypertension, coronary heart disease, stroke, diabetes, and breast, prostate and colon cancer. Recent epidemiologic data indicate an increased risk of Alzheimer's disease in association with adult obesity. There is now convincing evidence that, in both human and animal models, the in utero environment may impact on fetal developmental processes, altering offspring homeostatic regulatory mechanisms. "Gestational programming" may result in altered cell number, organ structure, hormonal set points or gene expression, with effects being permanent or expressed only at select offspring ages (e.g., newborn, adult). Our laboratory and others have demonstrated that low birth weight rats, induced by maternal food restriction or uterine artery ligation, paradoxically develop adult obesity with glucose intolerance and hypertension. Recent studies indicate alterations in peripheral (hepatic) and central (hippocampus) IGF-1 gene expression and epigenetic regulation among these offspring. These findings suggest that potential risk factors for the development of Alzheimer's disease may be present as early as newborn life.
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PMID:Gestational programming of offspring obesity: a potential contributor to Alzheimer's disease. 1743 Feb 49


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