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

Human immunodeficiency virus protease inhibitors are associated with metabolic abnormalities that may increase risk of atherosclerotic vascular disease, including dyslipidemia, insulin resistance, and central obesity. Dyslipidemia, characterized by hypercholesterolemia and hypertriglyceridemia, small low- and high-density lipoprotein particles, and in some cases lipoprotein(a) excess, can be severe and has been associated with endothelial dysfunction and carotid atherosclerosis. The mechanisms underlying protease inhibitor-associated dyslipidemia have not been elucidated completely, but appear to involve hepatic overproduction of very low-density lipoproteins and to a lesser extent, impaired clearance. Insulin resistance appears to mediate part of the adverse lipoprotein changes observed in patients taking protease inhibitors. Ongoing epidemiological and surrogate endpoint studies are investigating the atherogenicity of these medications. Until the risk associated with use of protease inhibitors is better understood, identifying patients at high risk for adverse vascular events such as heart attacks, cardiac death, and stroke is a high priority. This article reviews the lipid and lipoprotein abnormalities associated with use of protease inhibitors, possible mechanisms for protease inhibitor-associated dyslipidemia, its potential atherogenicity, and use of the National Cholesterol Education Program Adult Treatment Panel III Guidelines for the management of patients with dyslipidemia.
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PMID:Dyslipidemia in the era of HIV protease inhibitors. 1263 93

The obesity crisis in the United States has been associated with an alarming increase in the prevalence of the metabolic syndrome (MSX) disease cluster. Here we review evidence that the MSX reflects a failure of a system of intracellular lipid homeostasis that prevents lipotoxicity in the organs of overnourished individuals by confining the lipid overload to cells specifically designed to store large quantities of surplus calories, the white adipocytes. Normally, early in obesity, adipocytes increase leptin and adiponectin secretion, hormones that enhance oxidation of surplus liquids in nonadipose tissues by activating AMP-activated protein kinase and reducing the activity and expression of lipogenic enzymes. These events combine to lower malonyl coenzyme A. Deficiency of and/or unresponsiveness to leptin prevents these protective events and results in ectopic accumulation of lipids. Increased de novo ceramide formation is probably the most damaging lipid and is a cause of lipoapoptosis, abetted by a decline in tissue Bcl-2. Pancreatic beta-cells and myocardiocytes are cellular victims of the process, leading to non-insulin-dependent diabetes and lipotoxic cardiomyopathy. The MSX is particularly prevalent in visceral obesity, probably because visceral adipocytes make less leptin than sc adipocytes. Cushing's syndrome, the lipodystrophy associated with protease inhibitor therapy of AIDS, polycystic ovarian disease, as well as diet-induced visceral obesity, all have a high waist/hip ratio, and all exhibit MSX. Increased lipid content in the heart and skeletal muscle organs of such patients is now under study.
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PMID:Minireview: weapons of lean body mass destruction: the role of ectopic lipids in the metabolic syndrome. 1296 11

Surveys in HIV-infected men on antiretroviral therapy (ART) consistently demonstrate decreased levels of peripheral fat, with variable effects on central fat. This substudy of the Women's Interagency HIV Study was undertaken to examine fat distribution in a well-characterized cohort of HIV-positive and HIV-negative women in the United States. Whole-body dual-energy x-ray absorptiometry scanning with standardized regional analysis was performed in 271 nonpregnant women. Results were compared in the following groups: HIV negative (n = 88); and HIV positive on no ART (n = 70), highly active ART with a protease inhibitor (HAART/PI) (n = 48), or non-PI-containing HAART (n = 53). The groups were well matched with respect to race, with the majority of women coming from racial/ethnic minorities. The majority of both HIV-positive and HIV-negative women were overweight (body mass index [BMI] >/=25 kg/m), and many were obese (BMI >30 kg/m). Leg fat in both groups on HAART was significantly lower than in HIV-negative women (P = 0.01 and <0.0001 vs. HIV-negative for HAART/PI and HAART/no PI, respectively), whereas trunk fat was lower only in HAART/no PI (P = 0.0004 vs. HIV-negative). Thus, consistent with reports in men, lower levels of peripheral (leg) fat are seen in HIV-infected women on HAART, despite the high prevalence of obesity in this population.
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PMID:Fat distribution in HIV-infected women in the United States: DEXA substudy in the Women's Interagency HIV Study. 1560 19

Insulin resistance is accepted as the underlying fundamental defect that predates and ultimately leads to the development of type 2 (adult onset) diabetes mellitus in the general non-human immunodeficiency virus (HIV)-infected population. Insulin resistance is also a major component of the metabolic syndrome that, in association with other factors such as hypertension, hypercholesterolemia, and central obesity, defines a pre-diabetic atherogenic state that leads to adverse cardiovascular events. Growing evidence now suggests that mitochondrial dysfunction in skeletal muscle may be the mechanism whereby insulin resistance is induced. The prevalence of insulin resistance, glucose intolerance, and diabetes in the HIV-infected population has dramatically increased following the common use of highly active antiretroviral therapy (HAART). The development of insulin resistance in the HIV-infected population is likely to be multifactorial reflecting genetic predisposition, direct and indirect effects of both the protease inhibitor (PI) and nucleoside reverse transcriptase inhibitor (NRTI) class of antiretroviral therapy, and a possible contribution from chronic inflammatory changes induced by HIV. Indirect effects of antiretroviral therapy on insulin resistance may be mediated through both the visceral adiposity and peripheral fat depletion components of lipodystrophy as well as through fatty infiltration in liver and muscle. Based on current knowledge, mitochondrial dysfunction can be hypothesized to play a key role in each of these components.
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PMID:Insulin resistance in the HIV-infected population: the potential role of mitochondrial dysfunction. 1618 Nov 44

Metabolic Syndrome is a cluster of risk factors (including obesity, hypertension and insulin resistance), which is associated with late-onset diabetes and coronary heart disease. Elevated levels of the protease inhibitor PAI-1 are well-known molecular markers of the Metabolic Syndrome. Here, however, we present a hypothesis that PAI-1 acts as a causative factor in the development of Metabolic Syndrome and its clinical sequelae. We propose that PAI-1 inhibits the activity of members of the proprotein convertase (PC) class of serine proteases and that this underlies, at a molecular level, many of the other features of the Metabolic Syndrome cluster.
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PMID:Proposal of a novel diabetogenic mechanism involving the serpin PAI-1. 1670 57

To understand the molecular mechanisms underlying the development of dyslipidemia and lipodystrophy that occurs after administration of aspartic acid protease inhibitors, we examined transcriptional profiles using cDNA microarrays in 3T3-L1 adipocytes exposed to 10 micromol/l ritonavir for 2-21 days. The expression levels of approximately 12,000 transcripts were assessed using the MgU74Av2 mouse microarray chip. Ritonavir altered gene expression of inflammatory cytokines, stress response genes localized to endoplasmic reticulum, oxidative stress genes, apoptosis-related genes, and expression of genes involved in cell adhesion and extracellular matrix remodeling. Microarray analysis also identified a novel gene downregulated by ritonavir, Cidea, whose expression levels may affect free-fatty acid metabolism. These changes suggest a unique, stress-related pattern in adipocytes induced by chronic exposure to the protease inhibitor, ritonavir.
Obesity (Silver Spring) 2008 Oct
PMID:Effects of ritonavir on adipocyte gene expression: evidence for a stress-related response. 1871 45

The objective of the study was to identify predictors of obesity. One hundred eleven nonobese and 48 obese HIV-1 seropositive patients provided information on medical history and other characteristics. They were then asked to detect the passage of 2-s time intervals while the contingent negative variation (CNV) was recorded. Obese patients were healthier, more likely to be receiving Highly Active Antiretroviral Therapy, and less likely to be substance dependent. Obese patients also exhibited a greater CNV slope and responded prematurely. A path model suggested that CD4+count and protease inhibitor use directly predicted obesity. Depression had no direct effect. However, when incorporated into a hypothetical construct, "mood dysregulation," that also included childhood conduct problems and stimulant dependence, the shared variance among the indicators did predict obesity. This relationship was mediated through premature response preparation (anterior scalp CNV amplitude) and its hypothesized association with impatience/impulsivity.
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PMID:Psychiatric and neurophysiological predictors of obesity in HIV/AIDS. 1882 20

Adiponectin is a fat cell-derived hormone with insulin-sensitizing properties. Low plasma adiponectin levels are associated with insulin resistance as found in obesity. One of the mechanisms for this finding is hampered insulin signaling via phosphatidylinositol 3-kinase (PI3K) with concomitant decreased adiponectin secretion. Because insulin can also stimulate signaling at the level of mammalian target of rapamycin (mTOR) by a mechanism that is dependent on the presence of amino acids, the role of mTOR signaling in adiponectin secretion was studied. In view of the vesicular nature of adiponectin secretion, the role of lysosomes was explored as well. In 3T3-L1 adipocytes, both insulin and amino acids stimulated adiponectin secretion. The stimulation by insulin was PI3K dependent but mTOR independent. The stimulation by amino acids was independent of both PI3K and mTOR. Whereas the effect of insulin via PI3K was mainly on adiponectin secretion from adipocytes, the effect of amino acids was predominantly due to their role as substrates for adiponectin synthesis. The acidotropic agents ammonia and methylamine, but not the lysosomal protease inhibitor leupeptin and the autophagy inhibitor 3-methyladenine, strongly inhibited adiponectin secretion and increased the intracellular adiponectin pool. In conclusion, adiponectin production is substrate driven. Phosphatidylinositol 3-kinase and an acidic lysosomal pH, but not amino acid-mediated mTOR signaling or lysosomal breakdown, are involved in adiponectin secretion.
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PMID:Regulation of adiponectin secretion by insulin and amino acids in 3T3-L1 adipocytes. 1901 87

Intra-abdominal (IA) fat functionally differs from subcutaneous (SC) adipose tissue, likely contributing to its stronger association with obesity-induced morbidity and to differential response to medications. Drug-induced partial lipodystrophy, like in response to antiretroviral agents, is an extreme manifestation of the different response of different fat depots, with loss of SC but not IA. Investigating depot-specific adipocyte differences is limited by the low accessibility to IA fat and by the heterogenous cell population comprising adipose tissue. Here, we aimed at utilizing immortalized preadipocyte cell lines from IA (epididymal) or SC (inguinal) fat to investigate whether they differentially respond to the HIV protease inhibitor nelfinavir. Preadipocytes were readily amenable to adipogenesis, as evidenced by lipid accumulation, expression of adipose-specific genes, measurable lipolysis, and insulin responsiveness. Leptin secretion was higher by the SC line, consistent with known differences between IA and SC fat. As previously reported, nelfinavir inhibited adipogenesis downstream of C/EBPbeta, but similarly in both cell lines. In contrast, nelfinavir's capacity to diminish insulin signaling, decrease leptin secretion, enhance basal lipolysis, and decrease expression of the lipid droplet-associated protein perilipin occurred more robustly and/or at lower nelfinavir concentrations in the SC line. This was despite similar intracellular concentrations of nelfinavir (23.8 +/- 5.6 and 33.6 +/- 12.2 microg/mg protein for inguinal and epididymal adipocytes, respectively, P = 0.46). The cell lines recapitulated depot-differential effects of nelfinavir observed in differentiated primary preadipocytes and with whole tissue explants. Thus, we report the use of fat depot-specific adipocyte cell lines for unraveling depot-differential responses to a drug causing partial lipodystrophy.
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PMID:Depot-specific adipocyte cell lines reveal differential drug-induced responses of white adipocytes--relevance for partial lipodystrophy. 1903 43

Treatment for chronic hepatitis C virus (HCV) infection has evolved considerably in the last years. The standard of care (SOC) for HCV infection consists in the combination of pegylated interferon (PEG-IFN) plus ribavirin. However, it only induces a sustained virological response (SVR) in half of genotype 1-infected patients. Several viral and host factors have been associated with non-response: steatosis, obesity, insulin resistance, age, male sex, ethnicity and genotypes. Many studies have demonstrated that in non-responders, some interferon-stimulated genes were upregulated before treatment. Those findings associated to clinical, biochemical and histological data may help detect responders before starting any treatment. This is a very important issue because the standard treatment is physically and economically demanding. The future of HCV treatment would probably consist in the addition of specifically targeted antiviral therapy for HCV such as protease and/or polymerase inhibitors to the SOC. In genotype 1 patients, very promising results have been reported when the protease inhibitor telaprevir or boceprevir is added to the SOC. It increases the SVR rates from approximately 50% (PEG-IFN plus ribavirin) to 70% (for patients treated with a combination of PEG-IFN plus ribavirin plus telaprevir). Different elements are associated with non-response: (i) viral factors, (ii) host factors and (iii) molecular mechanisms induced by HCV proteins to inhibit the IFN signalling pathway. The goal of this review is to present the mechanisms of non-response, to overcome it and to identify factors that can help to predict the response to anti-HCV therapy.
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PMID:Hepatitis C: viral and host factors associated with non-response to pegylated interferon plus ribavirin. 2063 2


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