1451
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Martens FMAC, Visseren FLJ, de Koning EJP, Rabelink TJ. Short-term pioglitazone treatment improves vascular function irrespective of metabolic changes in patients with type 2 diabetes. J Cardiovasc Pharmacol 2005; 46:773-8. [PMID: 16306801 DOI: 10.1097/01.fjc.0000187176.13403.05] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To determine whether pioglitazone influences endothelial function directly, we examined in a randomized, crossover, placebo-controlled, double-blind trial the effects of 4 weeks of pioglitazone treatment in 20 male type 2 diabetic patients. We conclude that short-term pioglitazone treatment ameliorates endothelial dysfunction in conduit arteries irrespective of significant beneficial changes in plasma levels of insulin, FFA, adiponectin, or CRP in type 2 patients with diabetes. Pioglitazone, a PPARgamma agonist, not only improves insulin resistance and glycemic control but may also have additional beneficial vascular effects in patients with type 2 diabetes. Low-grade inflammation, free fatty acids, and adiponectin may play a role in modulation of vascular function. We studied the effect of 4 weeks of pioglitazone treatment on endothelial function, metabolic changes, and C-reactive protein in patients with type 2 diabetes. A randomized, crossover, placebo-controlled, double-blind trial was performed in which pioglitazone 30 mg once daily was administered to 20 patients with type 2 diabetes on oral antihyperglycemic agents for 4 weeks. Shear stress-induced flow-mediated dilation (FMD) of the brachial artery was used as outcome parameter for vascular function. Brachial artery endothelial function was significantly increased by pioglitazone treatment compared with placebo (FMD 5.4 +/- 0.5% versus 3.1 +/- 0.5%, P = 0.001). Endothelium-independent vasodilation was not different between the 2 study periods. Pioglitazone treatment reduced insulin, FFA, and C-reactive protein concentrations compared with placebo (18.3 +/- 2.4 versus 14.8 +/- 2.1 mU/L, P = 0.03; 641 +/- 46 versus 542 +/- 33 mumol/L, P = 0.04; and 3.5 +/- 0.6 mg/L versus 2.6 +/- 0.5 mg/L, P = 0.01; respectively). A significant increase in plasma adiponectin concentration (3.95 +/- 0.57 microg/mL versus 7.59 +/- 0.95 microg/mL, P = 0.002) was also observed. No correlations were found between these metabolic changes and the improvement of conduit artery endothelial function. Short-term pioglitazone treatment ameliorates endothelial dysfunction in conduit arteries irrespective of changes in insulin, FFA, adiponectin, or CRP in type 2 patients with diabetes.
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Affiliation(s)
- Fabrice M A C Martens
- Department of Internal Medicine, Section of Vascular Medicine and Diabetology, University Medical Center, Utrecht, The Netherlands.
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1452
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Sakharova OV, Inzucchi SE. Treatment of diabetes in the elderly. Addressing its complexities in this high-risk group. Postgrad Med 2005; 118:19-26, 29. [PMID: 16329527 DOI: 10.3810/pgm.2005.11.1684] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Diabetes is becoming increasingly common in the elderly, affecting more than one person in five. In this group, type 2 diabetes is by far the more prevalent form. Despite this major public health concern, evidence-based information specific to older adults with diabetes is surprisingly lacking. Complicating the medical picture, the elderly commonly have a host of comorbidities that can influence diabetes treatment and therapeutic goals. Here, the authors present an overview of therapy, discussing the antidiabetic agents available and their best use in the older population with diabetes.
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Affiliation(s)
- Olga V Sakharova
- Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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1453
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Abstract
Metabolic syndrome is asymptomatic and results from the increasing prevalence of obesity. Although several definitions exist and complicate its diagnosis, metabolic syndrome is characterized by the clustering of moderate troubles of glucose, lipid metabolism, body weight, hypertension and vascular inflammation ; the synergy between 3 of them triggers type 2 diabetes, atherosclerosis and associated clinical events. Whatever the age but particularly in adolescence, the prevalence of metabolic syndrome is high ; beyond lifestyle interventions, the available treatments address essentially a single risk factor and an unmet medical need persists. The reduction of cardiovascular events in secondary prevention has been demonstrated for some antidiabetic, hypolipidemic and antihypertensive agents but any difference in efficacy between populations with and without metabolic syndrome has yet to be established. The approval of metabolic syndrome as a specific therapeutic target would need the characterization of its pathogenic mechanism, a clearer guidance for definition and diagnosis, and the clinical proof of concept of a novel molecule displaying multifactorial impacts. Some new mechanistic approaches are discussed and may represent a breakthrough particularly if positive results of Field and Proactive clinical studies related to PPARs are disclosed soon.
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Affiliation(s)
- Didier Junquero
- Laboratoires Pierre Fabre, 17, avenue Jean Moulin, 81100 Castres, France.
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1454
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. YLZ, . JFT, . DVE. PTP1b: A Promising and Challenging Target for Metabolic Disease. INT J PHARMACOL 2005. [DOI: 10.3923/ijp.2006.93.97] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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1455
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Torrey CE, Wall HG, Campbell JA, Kwanyuen P, Hoivik DJ, Miller RT, Allen JS, Jayo MJ, Selinger K, Santostefano MJ. Evaluation of the carcinogenic potential of clofibrate in the FVB/Tg.AC mouse after dermal application--part II. Int J Toxicol 2005; 24:327-39. [PMID: 16257852 DOI: 10.1080/10915810500208199] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study was conducted as part of the International Life Sciences Institute (ILSI) Alternatives to Carcinogenicity Testing program and evaluated the carcinogenic potential of clofibrate, a nongenotoxic, peroxisome proliferator-activated receptor (PPAR) alpha agonist following dermal application to transgenic Tg.AC and nontransgenic FVB mice for a minimum of 26 weeks. Clofibrate doses of 12, 28, or 36 mg/200 microl/day were used. Positive controls for papilloma formation were benzene (174.8 mg/200 microl), and 12-o-tetradecanoylphorbol-13-acetate (TPA [0.00250 mg/200 microl]). Clofibrate was tolerated at doses up to 36 mg/200 microl. In Tg.AC mice, clofibrate produced a dose-related increase in the incidence of mice with cutaneous papillomas; and dose-related decreases in mean time to first tumor, mean multiplicity of tumors per mouse, and mean weeks to maximal yield, as well as numerous nonneoplastic microscopic lesions in the liver, kidney, spleen, and skin. Benzene and TPA induced both neoplastic and/or non-neoplastic proliferative lesions in Tg.AC mice. Clofibrate did not increase the incidence or multiplicity of papillomas, or any other tumors in FVB mice. These data show that the Tg.AC dermal model has increased sensitivity in detecting skin papillomas caused by the nongenotoxic rodent carcinogen, clofibrate, compared to wild type FVB mice, at systemic exposures that are 3x higher than the systemic exposure observed in humans taking clofibrate (AUC = 1100 microg.h/ml) at the recommended maximum therapeutic dose of 500 mg. In addition, this study supports the proposed concept that Tg.AC model may detect compounds with nongenotoxic carcinogenic potential in a shorter timeframe than conventional mouse carcinogenicity bioassays.
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Affiliation(s)
- Carla E Torrey
- GlaxoSmithKline, Safety Assessment, Research Triangle Park, North Carolina 27709, USA
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1456
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Torrey CE, Wall HG, Campbell JA, Kwanyuen P, Hoivik DJ, Miller RT, Allen JS, Jayo MJ, Selinger K, Savina PM, Santostefano MJ. Evaluation of the carcinogenic potential of clofibrate in the FVB/Tg.AC mouse after oral administration--part I. Int J Toxicol 2005; 24:313-25. [PMID: 16257851 DOI: 10.1080/10915810500208264] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study was conducted as part of the International Life Sciences Institute (ILSI) program to evaluate the carcinogenic potential of clofibrate, a nongenotoxic, peroxisome proliferator-activated receptor (PPAR) alpha agonist following oral administration to Tg.AC (transgenic) and wild-type FVB (nontransgenic) mice for a minimum for 6 months. Clofibrate was well tolerated at doses up to 500 (males) and 650 (females) mg/kg/day. Oral administration of clofibrate to Tg.AC or FVB (wild-type) male and female mice for 6 months did not result in the increased formation of neoplastic lesions. Epithelial hyperplasia in the urinary bladder (Tg.AC and FVB) and prostate gland (Tg.AC only), and interstitial-cell hyperplasia in the testes (Tg.AC) were noted at 500 mg/kg/day. Non-neoplastic nonproliferative findings included hepatic hypertrophy and hematopoietic changes (myeloid hyperplasia, myelodysplasia, lymphoid depletion, and erythropoiesis) in Tg.AC and FVB mice of both sexes; reproductive (cystic degeneration and dilatation, hypospermia, spermatocele, dilated inspissated protein) and urogenital (tubular-cell hypertrophy, degenerative/regenerative nephropathy, necrosis/fibrosis) changes in Tg.AC and FVB male mice; congestion in the lung in male Tg.AC mice; gall bladder dilatation in female Tg.AC mice; and adrenal (intracellular lipofuscinosis and atrophy) and heart (eosinophillic myofibers) findings in Tg.AC mice of both sexes and in female FVB mice. The results of this study indicate that the clofibrate is not carcinogenic when administered to Tg.AC mice by oral gavage for 6 months at doses up to 500 (males) and 650 (females) mg/kg/day, which did produce liver hypertrophy.
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Affiliation(s)
- Carla E Torrey
- GlaxoSmithKline, Safety Assessment, Research Triangle Park, North Carolina 27709, USA
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1457
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Nesfield SR, Clarke CJ, Hoivik DJ, Miller RT, Allen JS, Selinger K, Santostefano MJ. Evaluation of the carcinogenic potential of clofibrate in the rasH2 mouse. Int J Toxicol 2005; 24:301-11. [PMID: 16257850 DOI: 10.1080/10915810500210278] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The purpose of the study was to support of the International Life Sciences Institute (ILSI) alternative carcinogenicity models initiative to evaluate the carcinogenic potential of the nongenotoxic carcinogen, clofibrate, a peroxisome proliferator-activated receptor (PPAR) alpha agonist, following oral administration to rasH2 mice. Peroxisome proliferators are one of the most widely studied of the nongenotoxic carcinogens and have diverse industrial and therapeutic uses (Gonzalez et al. J. Nat. Cancer Inst. 90: 1702-1709, 1998); however, the nongenotoxic mechanism of carcinogenicity is currently unknown. Male mice were administered doses of clofibrate at 50, 100, or 200 mg/kg/day and female mice were administered doses of 50, 150, or 250 mg/kg/day by oral gavage at 10 ml/kg for 27 weeks. In addition, rasH2 male and female mice were treated with N-nitroso-N-methylurea (NMU). Nontransgenic male and female mice were treated with 200 and 250 mg/kg/day, respectively, of clofibrate. The NMU-treated mice were given a single intraperitoneal dose of 75 mg/kg, which was followed by a 90-day observation period; all others were sacrificed after 6 months of daily dosing. Hepatocellular neoplasms were observed in clofibrate-treated rasH2 male mice after 6 months of treatment but not in nontransgenic males or females. Clofibrate treatment (250 mg/kg/day) of female rasH2 mice was associated with a slight increase in the incidence of various neoplasms (harderian gland, lungs, skin, spleen, tail, thymus, and uterus) compared with untreated transgenic mice and with similarly treated nontransgenic mice. Non-neoplastic changes were found in the liver of transgenic and nontransgenic mice of both sexes and in the kidneys of male mice. NMU produced findings are consistent with previous studies. The data suggest that the rasH2 mice are a good model for testing epigenetic carcinogens in a shorter timeframe than conventional mouse carcinogenicity bioassays.
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1458
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Affiliation(s)
- Robert Rizza
- American Diabetes Association, 1701 N. Beauregard Street, Alexandria, VA 22311, USA.
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1459
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Abstract
Polycystic ovarian syndrome (PCOS), first described in 1937, was defined by specific ovarian histopathology and a constellation of signs and symptoms. Through the years, the etiology remained elusive, with heated debates focusing in turn on the ovary and then the pituitary as the causative agents. In the last several decades, it has become clear that insulin resistance makes up a very important component of this syndrome. With this knowledge, new therapies have emerged along with the realization that PCOS and the metabolic syndrome are closely related through their shared insulin resistance. In this review, the diagnosis, pathophysiology, and therapy of PCOS are discussed and upon this background, those areas held in common by PCOS and the metabolic syndrome are explored.
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Affiliation(s)
- Belinda M Sartor
- Section of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Louisiana State University School of Medicine, Fertility Institute of New Orleans, Louisiana 70001, USA
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1460
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Gurnell M. Peroxisome proliferator-activated receptor gamma and the regulation of adipocyte function: lessons from human genetic studies. Best Pract Res Clin Endocrinol Metab 2005; 19:501-23. [PMID: 16311214 DOI: 10.1016/j.beem.2005.10.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In recent years, the thiazolidinediones (e.g. rosiglitazone, pioglitazone) have emerged as an exciting novel class of therapeutic agent for the treatment of type 2 diabetes mellitus and the human metabolic syndrome. At first glance, the use of these high-affinity peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, that promote adipogenesis, to treat a group of disorders that typically have their origins in obesity seems counter-intuitive. However, to view PPARgamma simply as a regulator of fat mass, and adipocytes themselves as passive vessels for energy storage, is to ignore an extensive body of data that speaks of the diverse roles of both this receptor and adipose tissue in the maintenance of normal metabolic homeostasis. This article highlights the important clinical and laboratory observations made in human subjects harbouring genetic variations in PPARgamma that have confirmed its pivotal role in the regulation of adipocyte endocrine function, and thus our metabolic response to the environment.
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Affiliation(s)
- Mark Gurnell
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, UK.
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1461
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Tilg H, Kaser A. Treatment strategies in nonalcoholic fatty liver disease. ACTA ACUST UNITED AC 2005; 2:148-55. [PMID: 16265156 DOI: 10.1038/ncpgasthep0116] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Accepted: 02/11/2005] [Indexed: 12/26/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is an increasingly recognized health problem. Increased fat accumulation in the liver is observed in 20-30% of the population in the Western world, and in approximately 10% of this cohort it is associated with nonalcoholic steatohepatitis, which is characterized by inflammation and fibrosis. Disease presentation of NAFLD ranges from asymptomatic disease to cirrhosis with the complication of liver failure and hepatocellular carcinoma. NAFLD is suspected on the basis of various clinical aspects (an elevated alanine aminotransferase concentration, presence of obesity and diabetes) that alone are not sufficient to establish diagnosis or prognosis. The major diagnostic procedure is liver biopsy, which allows assessment of liver injury. In most cases, NAFLD is associated with insulin resistance, which is therefore the target of most current NAFLD treatment modalities. Various treatment strategies such as weight loss and/or exercise, thiazolidinediones, metformin, lipid-lowering agents and antioxidants have been studied. So far, no single intervention has convincingly improved liver histology. It is recommended that patients at high risk of developing advanced liver disease, and who are not part of controlled studies, should receive nutritional counseling and take physical exercise to achieve moderate weight loss and improve insulin sensitivity.
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Affiliation(s)
- Herbert Tilg
- Department of Medicine, Academic Teaching Hospital Hall, Tyrol, Austria.
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1462
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Reynaert H, Geerts A, Henrion J. Review article: the treatment of non-alcoholic steatohepatitis with thiazolidinediones. Aliment Pharmacol Ther 2005; 22:897-905. [PMID: 16268963 DOI: 10.1111/j.1365-2036.2005.02682.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
It is generally accepted that non-alcoholic fatty liver disease will be the most frequent liver disease in the near future and that the management of patients with non-alcoholic fatty liver disease will be a challenge for hepatologists in the next decades. Non-alcoholic fatty liver disease is considered the hepatic manifestation of the metabolic syndrome, in which insulin resistance plays a crucial role. Although steatosis will often not progress to severe liver disease, in some patients, it results in cirrhosis and even hepatocellular carcinoma. Therefore, it is important to identify those patients at risk for developing fibrosis. Age, diabetes, obesity and hypertriglyceridaemia are independent risk factors for fibrosis in patients with elevated serum alanine aminotransferase levels and steatosis on ultrasound. The presence of multiple metabolic disorders increases the risk. Apart from diet, exercise and correction of underlying metabolic abnormalities, no specific treatment is available at the moment. Theoretically, thiazolidinediones are an attractive way to treat non-alcoholic fatty liver disease, because they improve insulin resistance. Some preliminary studies with thiazolidinediones were encouraging, as steatosis, inflammation and fibrosis improved in a substantial number of patients. Although no serious side effects occurred in the pilot studies, we should look vigilantly for hepatotoxicity, as the first generation thiazolidinediones proved to be toxic for the liver.
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Affiliation(s)
- H Reynaert
- Department of Gastroenterology-Hepatology, University Hospital AZ-VUB, Brussels, Belgium.
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1463
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Szapary PO, Bloedon LT, Samaha FF, Duffy D, Wolfe ML, Soffer D, Reilly MP, Chittams J, Rader DJ. Effects of pioglitazone on lipoproteins, inflammatory markers, and adipokines in nondiabetic patients with metabolic syndrome. Arterioscler Thromb Vasc Biol 2005; 26:182-8. [PMID: 16284192 DOI: 10.1161/01.atv.0000195790.24531.4f] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE The purpose of this research was to evaluate the short-term effects of pioglitazone (PIO) on high-density lipoprotein cholesterol (HDL-C) and other metabolic parameters in nondiabetic patients with metabolic syndrome (MetSyn). METHODS AND RESULTS Sixty nondiabetic adults with low HDL-C and MetSyn were randomized to PIO or matching placebo for 12 weeks. PIO increased HDL-C by 15% and 14% at 6 and 12 weeks, respectively, compared with placebo (P<0.001). Changes in HDL-C were correlated to changes in adiponectin (r=0.34; P=0.01) but not to changes in insulin resistance. PIO did not affect serum triglycerides or low-density lipoprotein (LDL) cholesterol concentrations but reduced the number of small LDL particles by 18% (P<0.001). PIO reduced median C-reactive protein levels by 31% (P<0.001) and mean resistin levels by 10% (P=0.02) while increasing mean serum levels of adiponectin by 111% (P<0.001) compared with placebo. PIO did not affect weight and modestly decreased insulin resistance. CONCLUSIONS In nondiabetic patients with low HDL-C and MetSyn, PIO significantly raised HDL-C and favorably affected lipoprotein particle size, markers of inflammation, and adipokines without changes in triglycerides, LDL-C, or weight. These results suggest that PIO has direct effects on HDL, which may contribute to its antiatherogenic effects.
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Affiliation(s)
- Philippe O Szapary
- Division of General Internal Medicine, Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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1464
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Ledingham JM, Laverty R. Effects of glitazones on blood pressure and vascular structure in mesenteric resistance arteries and basilar artery from genetically hypertensive rats. Clin Exp Pharmacol Physiol 2005; 32:919-25. [PMID: 16405447 DOI: 10.1111/j.1440-1681.2005.04285.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. The effects of two of the glitazone (thiazolidinedione) class of drugs, namely rosiglitazone and pioglitazone, on blood pressure and vascular remodelling in the New Zealand genetically hypertensive (GH) rat model were investigated. 2. In the first study, a GH group given rosiglitazone (5 mg/kg per day) from the age of 7 to 12 weeks was compared with a GH control group. In the second study, GH rats were given either pioglitazone, simvastatin, valsartan or combinations of pioglitazone with simvastatin or valsartan (all drugs at a dose of 10 mg/kg per day). 3. Tail-cuff systolic blood pressure was measured weekly. At the end of the experiment, blood vessels were fixed by perfusion and samples of mesenteric resistance arteries (MRA), second-order branches and basilar artery were embedded in Technovit and serial sections were cut and stained with Giemsa for stereological analysis. Media width, medial cross-sectional area and lumen diameter were determined and the ratio of media width/lumen diameter was calculated. 4. Rosiglitazone significantly reduced blood pressure in GH rats. 5. In MRA, rosiglitazone had a hypotrophic effect on media, reduced lumen diameter and reduced media/lumen ratio (P<0.001). 6. In basilar artery, there was also a hypotrophic effect of rosiglitazone on media and reduced media/lumen ratio (P<0.001). 7. Pioglitazone slowed down the rate of blood pressure increase with age in GH rats and had a greater effect on blood pressure when given in combination with simvastatin. 8. Pioglitazone had a hypotrophic effect on the media of MRA and basilar artery. The hypotrophic effect was enhanced when pioglitazone was given in combination with simvastatin. The media/lumen ratio was reduced by pioglitazone; in MRA, combination treatment with simvastatin reduced the ratio further to normal and, with valsartan, to below normal. In basilar artery, the media/lumen ratio was reduced further by both combination treatments, but was lowest in the pioglitazone-valsartan combination group. 9. The significant effects on MRA and basilar artery structure (and, thus, haemodynamics) seen after rosiglitazone monotherapy and after pioglitazone, given alone and in combination with simvastatin or valsartan, may well indicate a glitazone class effect on vascular structure and, hence, cardiovascular function.
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Affiliation(s)
- Janet M Ledingham
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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1465
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Santostefano MJ, Hoivik DJ, Miller RT. Investigations of clofibrate in alternative carcinogenicity models. Int J Toxicol 2005; 24:285-8. [PMID: 16257848 DOI: 10.1080/10915810500210369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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1466
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Teede HJ, Meyer C, Norman RJ. Insulin-sensitisers in the treatment of polycystic ovary syndrome. Expert Opin Pharmacother 2005; 6:2419-27. [PMID: 16259573 DOI: 10.1517/14656566.6.14.2419] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine condition with reproductive and metabolic implications. In the current setting there is an evolving, yet inadequate, understanding of the pathophysiology, long-term health implications and ideal therapies for women with PCOS. Insulin resistance, secondary to both genetic and lifestyle factors, is integrally involved in the pathogenesis, the metabolic and clinical features and the long-term sequelae of PCOS in a majority of patients. Therapeutic strategies targeting insulin resistance ameliorate clinical features and may reduce long-term sequelae of PCOS, including diabetes. The main benefit of improved insulin resistance is to improve fertility and potentially to improve clinical features of hyperandrogenism and lower androgen levels. Insulin sensitisers also have the potential to delay the development of diabetes and cardiovascular disease in PCOS. Lifestyle therapy is indicated as the first intervention; however, metformin as an insulin sensitising agent has a role in first-line medical therapy in women with PCOS. Further research is needed to define the role of insulin sensitisers in PCOS and to determine the long-term risks and benefits of these therapies.
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Affiliation(s)
- Helena J Teede
- Jean Hailes Foundation, Monash Institute of Health Services Research, Monash Medical Centre, Level 1 Block E, Locked Bag 29 Clayton VIC 3168, Australia.
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1467
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Abstract
The adipocyte has pleiotropic functions beyond the storage of energy in times of nutrient abundance. Considerable efforts in adipocyte biology within the past ten years have emphasized the important role of adipose tissue in processes as diverse as energy metabolism, inflammation and cancer. Adipocytes are able to communicate with the brain and peripheral tissues implementing metabolic signals such as satiety, food intake and energy expenditure. Despite its huge pharmacological potential, only a small number of clinical applications interfere directly with adipocyte physiology. Here, we want to highlight various areas of adipocyte physiology that have not yet been explored pharmacologically and emphasize some of the limitations associated with these pharmacotherapies.
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Affiliation(s)
- Andrea R Nawrocki
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
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1468
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Affiliation(s)
- Hannele Yki-Järvinen
- Department of Medicine, Division of Diabetes, University of Helsinki, PO Box 340, Haartmaninkatu 4, 00290 Helsinki, Finland.
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1469
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Dormandy JA, Charbonnel B, Eckland DJA, Erdmann E, Massi-Benedetti M, Moules IK, Skene AM, Tan MH, Lefèbvre PJ, Murray GD, Standl E, Wilcox RG, Wilhelmsen L, Betteridge J, Birkeland K, Golay A, Heine RJ, Korányi L, Laakso M, Mokán M, Norkus A, Pirags V, Podar T, Scheen A, Scherbaum W, Schernthaner G, Schmitz O, Skrha J, Smith U, Taton J. Secondary prevention of macrovascular events in patients with type 2 diabetes in the PROactive Study (PROspective pioglitAzone Clinical Trial In macroVascular Events): a randomised controlled trial. Lancet 2005; 366:1279-89. [PMID: 16214598 DOI: 10.1016/s0140-6736(05)67528-9] [Citation(s) in RCA: 2906] [Impact Index Per Article: 152.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Patients with type 2 diabetes are at high risk of fatal and non-fatal myocardial infarction and stroke. There is indirect evidence that agonists of peroxisome proliferator-activated receptor gamma (PPAR gamma) could reduce macrovascular complications. Our aim, therefore, was to ascertain whether pioglitazone reduces macrovascular morbidity and mortality in high-risk patients with type 2 diabetes. METHODS We did a prospective, randomised controlled trial in 5238 patients with type 2 diabetes who had evidence of macrovascular disease. We recruited patients from primary-care practices and hospitals. We assigned patients to oral pioglitazone titrated from 15 mg to 45 mg (n=2605) or matching placebo (n=2633), to be taken in addition to their glucose-lowering drugs and other medications. Our primary endpoint was the composite of all-cause mortality, non fatal myocardial infarction (including silent myocardial infarction), stroke, acute coronary syndrome, endovascular or surgical intervention in the coronary or leg arteries, and amputation above the ankle. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN NCT00174993. FINDINGS Two patients were lost to follow-up, but were included in analyses. The average time of observation was 34.5 months. 514 of 2605 patients in the pioglitazone group and 572 of 2633 patients in the placebo group had at least one event in the primary composite endpoint (HR 0.90, 95% CI 0.80-1.02, p=0.095). The main secondary endpoint was the composite of all-cause mortality, non-fatal myocardial infarction, and stroke. 301 patients in the pioglitazone group and 358 in the placebo group reached this endpoint (0.84, 0.72-0.98, p=0.027). Overall safety and tolerability was good with no change in the safety profile of pioglitazone identified. 6% (149 of 2065) and 4% (108 of 2633) of those in the pioglitazone and placebo groups, respectively, were admitted to hospital with heart failure; mortality rates from heart failure did not differ between groups. INTERPRETATION Pioglitazone reduces the composite of all-cause mortality, non-fatal myocardial infarction, and stroke in patients with type 2 diabetes who have a high risk of macrovascular events.
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Affiliation(s)
- John A Dormandy
- Department of Clinical Vascular Research, Ingelby House, St Georges Hospital, Blackshaw Road, London SW17 0QT, UK.
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1470
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Sussman F, de Lera AR. Ligand recognition by RAR and RXR receptors: binding and selectivity. J Med Chem 2005; 48:6212-9. [PMID: 16190748 DOI: 10.1021/jm050285w] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fundamental biological functions, most notably embriogenesis, cell growth, cell differentiation, and cell apoptosis, are in part regulated by a complex genomic network that starts with the binding (and activation) of retinoids to their cognate receptors, members of the superfamily of nuclear receptors. We have studied ligand recognition of retinoic receptors (RXRalpha and RARgamma) using a molecular-mechanics-based docking method. The protocol used in this work is able to rank the affinity of pairs of ligands for a single retinoid receptor, the highest values corresponding to those that adapt better to the shape of the binding site and generate the optimal set of electrostatic and apolar interactions with the receptor. Moreover, our studies shed light onto some of the energetic contributions to retinoid receptor ligand selectivity. In this regard we show that there is a difference in polarity between the binding site regions that anchor the carboxylate in RAR and RXR, which translates itself into large differences in the energy of interaction of both receptors with the same ligand. We observe that the latter energy change is canceled off by the solvation energy penalty upon binding. This energy compensation is borne out as well by experiments that address the effect of site-directed mutagenesis on ligand binding to RARgamma. The hypothesis that the difference in binding site polarity might be exploited to build RXR-selective ligands is tested with some compounds having a thiazolidinedione anchoring group.
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Affiliation(s)
- Fredy Sussman
- Departamento de Química Orgánica, Facultad de Química, Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain.
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1471
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Halimi S. Nouvelles stratégies thérapeutiques dans le diabète de type 2? Presse Med 2005; 34:1287-92. [PMID: 16269991 DOI: 10.1016/s0755-4982(05)84175-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Earlier guidelines for type 2 diabetes (Afssaps 1999 and Anaes 2000) were based on the UK Prospective Diabetes Study, published in 1998. These guidelines recommended treatment according to HbA1c value (< 6.5%, between 6.5 and 8% and > 8%): an oral antidiabetic agent for levels > 6.5% despite diet and exercise; combined metformin + sulfonylurea) if HbA1c >8%; and insulin if the latter failed. Blood pressure goals were < 130/80 mmHg, with the antihypertensives necessary to achieve it. The LDL-cholesterol target value was < 1 g/L (for primary prevention in the case of high cardiovascular risk or for secondary prevention) or between 1.3 and 1.6 g/l (primary prevention in the absence of elevated risk). Another reading of the UK study, associated with the arrival of glitazones led to a revision of these objectives with a more aggressive treatment approach ("earlier and stronger"): screen patients for type 2 diabetes earlier, set stricter goals (HbA1c < 6%), and promptly prescribe dual therapy (metformin + sulfonylurea). Should this fail, either glitazone should be added or insulin treatment begun. For most people with type 2 diabetes, the target blood pressure remains 130/80 mmHg, regardless of the type and number of antihypertensive agents necessary. The target drops to 125/75 mmHg for patients with > 300 mg/day microalbuminuria; in these cases, treatment with agents that block the renin-angiotensin system (ACE inhibitors or sartans) is recommended. The LDL cholesterol target value is 1.0 or 1.6 g/L, depending on the cardiovascular risk level. But these guidelines are applied insufficiently, especially in terms of clinical and laboratory follow-up of patients and choice of treatment. All health professionals must participate in the more effective diffusion and application of these guidelines. Patient education is fundamental. The establishment of care networks for these patients seems to us to be the best tool for meeting the objectives of these guidelines.
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Affiliation(s)
- S Halimi
- Secteur diabétologie nutrition, Dune (Département uro-néphro-endocrinologie), CHU de Grenoble.
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1472
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1473
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Fiorucci S, Rizzo G, Antonelli E, Renga B, Mencarelli A, Riccardi L, Morelli A, Pruzanski M, Pellicciari R. Cross-talk between farnesoid-X-receptor (FXR) and peroxisome proliferator-activated receptor gamma contributes to the antifibrotic activity of FXR ligands in rodent models of liver cirrhosis. J Pharmacol Exp Ther 2005; 315:58-68. [PMID: 15980055 DOI: 10.1124/jpet.105.085597] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The nuclear receptors farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR)gamma exert counter-regulatory effects on hepatic stellate cells (HSCs) and protect against liver fibrosis development in rodents. Here, we investigated whether FXR ligands regulate PPARgamma expression in HSCs and models of liver fibrosis induced in rats by porcine serum and carbon tetrachloride administration and bile duct ligation. Our results demonstrate that HSCs trans-differentiation associated with suppression of PPARgamma mRNA expression, whereas FXR mRNA was unchanged. Exposure of cells to natural and synthetic ligands of FXR, including 6-ethyl chenodeoxycholic acid (6-ECDCA), a synthetic derivative of chenodeoxycholic acid, reversed this effect and increased PPARgamma mRNA by approximately 40-fold. Submaximally effective concentrations of FXR and PPARgamma ligands were additive in inhibiting alpha1(I) collagen mRNA accumulation induced by transforming growth factor (TGF)beta1. Administration of 6-ECDCA in rats rendered cirrhotic by porcine serum and carbon tetrachloride administration or bile duct ligation reverted down-regulation of PPARgamma mRNA expression in HSCs. Cotreatment with 6-ECDCA potentiates the antifibrotic activity of rosiglitazone, a PPARgamma ligand, in the porcine serum model as measured by morphometric analysis of liver collagen content, hydroxyproline, and liver expression of alpha1(I) collagen mRNA, alpha-smooth muscle actin, fibronectin, TGFbeta1, and tissue inhibitor of metalloprotease 1 and 2, whereas it enhanced the expression of PPARgamma and uncoupling protein 2, a PPARgamma-regulated gene, by 2-fold. In conclusion, by using an in vitro and in vivo approach, we demonstrated that FXR ligands up-regulate PPARgamma mRNA in HSCs and in rodent models of liver fibrosis. A FXR-PPARgamma cascade exerts counter-regulatory effects in HSCs activation.
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Affiliation(s)
- Stefano Fiorucci
- Dipartimento de Medicina Clinica e Sperimentale, Università degli Studi di Perugia, Italy.
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1474
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Ledl M, Hohenecker J, Francesconi C, Roots I, Bauer MF, Roden M. Acute myopathy in a type 2 diabetic patient on combination therapy with metformin, fenofibrate and rosiglitazone. Diabetologia 2005; 48:1996-8. [PMID: 16132947 DOI: 10.1007/s00125-005-1919-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 06/07/2005] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS This report describes the case of a 75-year-old male type 2 diabetic Caucasian who was admitted to the clinical ward because of acute pain and cramps in both calf muscles. MATERIALS AND METHODS Neuromuscular function was assessed by electromyography and electroneurography of the right leg. An open biopsy was taken from the left vastus lateralis muscle for histological and histochemical analyses. Southern blotting was performed to detect defects in mitochondrial DNA and tRNA. Cytochrome P450 (CYP-P450) polymorphisms were analysed in blood cells. RESULTS Fifteen weeks before admission, the patient's lipid-lowering medication was switched from simvastatin to fenofibrate because of predominant hypertriglyceridaemia; this did not affect creatine kinase levels. Three weeks before admission, rosiglitazone was added to his existing metformin therapy because of worsening metabolic control. Upon admission, serum enzymes indicating myopathy were elevated (creatine kinase 6897 U/l, myoglobin 902 ng/ml) and kidney function was impaired (creatinine 0.116 mmol/l, blood urea nitrogen 2.3 mmol/l). Electrophysiology revealed myopathy and sensory polyneuropathy. Histology showed multiple damage of the myofibrillar architecture. There was no evidence of defects in mitochondrial DNA or tRNA. Furthermore, no functional limitations in CYP2C9, CYP2C19 and CYP2D6 were detected. Following withdrawal of the oral medication and intravenous hydration, clinical symptoms and laboratory parameters gradually decreased. CONCLUSIONS/INTERPRETATION Until more data from controlled trials are available, we recommend that combination therapy with fibrates and thiazolidinediones should be monitored frequently by measurements of serum creatine kinase and creatinine, specifically in patients with pre-existing nephropathy and polyneuropathy.
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Affiliation(s)
- M Ledl
- First Medical Department, Hanusch Hospital, Heinrich Collin Strasse 30, A-1140, Vienna, Austria
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1475
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Abstract
The coexistence of type 2 diabetes and obesity presents a complex therapeutic challenge. Future combination tablets may include agents to address diabetes and any accompanying cardiovascular risk factors. Injectable agents that improve glycemic control and facilitate weight loss have recently become available: the soluble amylin analogue pramlintide provides an adjunct to insulin therapy in type 1 and type 2 diabetes, and the incretin mimetic exenatide can enhance prandial insulin release in type 2 diabetes. Orally active inhibitors of the incretin-degrading enzyme dipeptidyl peptidase-IV, agonists of peroxisome proliferator-activated receptor (PPAR)-a and PPAR-g ("dual PPARs"), and the CB1 cannabinoid receptor inhibitor rimonabant are advanced in clinical development. Many novel antidiabetic and antiobesity compounds are emerging in preclinical development.
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Affiliation(s)
- Clifford J Bailey
- Diabetes Group, Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
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1476
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Raz I, Stranks S, Filipczak R, Joshi P, Lertoft B, Rastam J, Chow CC, Shaban J. Efficacy and safety of biphasic insulin aspart 30 combined with pioglitazone in type 2 diabetes poorly controlled on glibenclamide (glyburide) monotherapy or combination therapy: An 18-week, randomized, open-label study. Clin Ther 2005; 27:1432-43. [PMID: 16291416 DOI: 10.1016/j.clinthera.2005.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2005] [Indexed: 11/28/2022]
Abstract
BACKGROUND Few large randomized controlled trials have assessed the value of adding insulin to an oral antidiabetic drug regimen. OBJECTIVE This trial compared the efficacy and safety of biphasic insulin aspart 30/70 (BIAsp 30) plus pioglitazone (n = 93), glibenclamide (glyburide) plus pioglitazone (n = 91), or BIAsp 30 monotherapy (n = 97). METHODS This 18-week, multinational, multicenter, randomized, open-label, parallel-group trial involved 281 patients with type 2 diabetes (60% male; mean age, 56 years; mean body mass index, 29.5 kg/m2) with inadequate glycemic control (mean glycosylated hemoglobin [HbA(1c)], 9.5%; range, 7.4%-14.7%) on glibenclamide monotherapy or combination therapy. The primary objective was to compare end-of-trial HbA(1c) among the 3 treatment groups. Fasting and mean 7- and 8-point blood glucose profiles, blood lipid levels, plasminogen activator inhibitor levels, adverse events, and hypoglycemia frequency were also compared. Patients using BIAsp 30 (alone or with pioglitazone) were injected twice daily (immediately before breakfast and dinner). Pioglitazone (30 mg/d) and glibenclamide (5-15 mg/d) were taken orally once daily with or immediately after breakfast. RESULTS At the end of the trial, HbA(1c) was significantly lower for the BIAsp 30 plus pioglitazone group than for the glibenclamide plus pioglitazone group (mean [SD], -0.64% [0.23%]; P = 0.005) and the BIAsp 30 monotherapy group (-0.60% [0.22%]; P = 0.008). Mean (SD) fasting blood glucose (before breakfast) was significantly lower for BIAsp 30 plus pioglitazone than for glibenclamide plus pioglitazone (153 [45] mg/dL vs 169 [65] mg/dL, respectively; P = 0.012). Each time point on the 8-point blood glucose profile was lower for BIAsp 30 plus pioglitazone than for glibenclamide plus pioglitazone (P < 0.001 to P < 0.05). No major hypoglycemic episodes were reported, and the absolute rate of hypoglycemic events was low (<1 event/patient-week) in the BIAsp-only group. Edema was reported in < or =9% of patients in each treatment group, but no occurrence was classified as serious. Weight gain (mean, 4.0 kg) was more common in the BIAsp plus pioglitazone group (8%); however, this was consistent with improved glycemic control and is similar to that reported in other pioglitazone trials. CONCLUSIONS BIAsp 30 plus pioglitazone provided an efficacious and well-tolerated treatment alternative to glibenclamide plus pioglitazone or BIAsp 30 alone in this population of patients who previously were not well controlled on glibenclamide monotherapy or combination therapy.
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Affiliation(s)
- Itamar Raz
- Diabetes Unit, Hadassah Hebrew University Hospital, Jerusalem, Israel.
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1477
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Abstract
Polycystic ovary syndrome (PCOS) is a syndrome of variable combinations of menstrual irregularity, hirsutism or acne, and obesity. It can be diagnosed in adolescence and has early childhood antecedents. PCOS is the single most common endocrine cause of an ovulatory infertility and a major risk factor for the metabolic syndrome and, in turn, development of type 2 diabetes mellitus in women. Thus, it appears that PCOS increases a woman's risk of developing cardiovascular disease. Therefore, identifying girls at risk for PCOS and implementing treatment early in the development of PCOS may be an effective means of preventing some of the long-term complications associated with this syndrome. This article reviews the definition, clinical features, diagnosis, and treatment of PCOS.
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Affiliation(s)
- Colleen Buggs
- Department of Pediatrics, The University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA.
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1478
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Lautamäki R, Airaksinen KEJ, Seppänen M, Toikka J, Luotolahti M, Ball E, Borra R, Härkönen R, Iozzo P, Stewart M, Knuuti J, Nuutila P. Rosiglitazone improves myocardial glucose uptake in patients with type 2 diabetes and coronary artery disease: a 16-week randomized, double-blind, placebo-controlled study. Diabetes 2005; 54:2787-94. [PMID: 16123370 DOI: 10.2337/diabetes.54.9.2787] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Rosiglitazone therapy improves insulin sensitivity and glucose uptake in patients with uncomplicated type 2 diabetes. In coronary artery disease (CAD), glucose is an important source of energy and preserved myocardial glucose uptake is essential for the viability of jeopardized myocardium. The aim was to test whether rosiglitazone changes myocardial metabolism in type 2 diabetic patients with CAD. We studied 54 patients (38 men and 16 women) with type 2 diabetes (HbA(1c) 7.2 + 0.9%) and CAD. Myocardial glucose uptake was measured with [(18)F]fluoro-2-deoxy-d-glucose positron emission tomography in ischemic (evaluated by single-photon emission tomography and coronary angiography) and nonischemic regions during euglycemic-hyperinsulinemic clamp before and after a 16-week intervention period with rosiglitazone (n = 27) or placebo (n = 27). Rosiglitazone significantly improved glycemic control (P < 0.0001) and whole-body insulin sensitivity (P < 0.0001). Rosiglitazone increased myocardial glucose uptake from 20.6 +/- 11.8 to 25.5 +/- 12.4 micromol . 100 g(-1) . min(-1) (P = 0.038 vs. baseline, P = 0.023 vs. placebo) in ischemic regions and from 21.7 +/- 12.1 to 28.0 +/- 12.7 micromol . 100 g(-1) . min(-1) (P = 0.014 vs. baseline, P = 0.003 vs. placebo) in nonischemic regions. The increase in myocardial glucose uptake was partly explained by the suppression of free fatty acid levels during clamp. Rosiglitazone therapy significantly increased insulin sensitivity and improved myocardial glucose uptake in type 2 diabetic patients with CAD. These results suggest that rosiglitazone therapy may facilitate myocardial glucose storage and utilization in these patients.
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Affiliation(s)
- Riikka Lautamäki
- Turku PET Centre, Turku University Central Hospital, Kiinamyllynkatu 4-8, P.O. Box 52, FIN-20521 Turku, Finland.
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1479
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Abstract
We speculated that the rise in atmospheric oxygen from 2 billion years ago was so integral for the evolution of biocomplexity that it must also associate strongly with complex diseases. As a remote test of this idea, we hypothesized that lines contrasting for disease and health would emerge from artificial selection for low and high aerobic treadmill running capacity. Eleven generations of selection in rats produced lines that differed by 347% in running capacity. The low line demonstrated health risk factors including higher visceral adiposity, blood pressure, insulin, and triglycerides. The high line was superior for VO2max, economy of running, heart function, and nitric oxide-induced vascular dilation.
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Affiliation(s)
- Steven Loyal Britton
- Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, Michigan 48109, USA.
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1480
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Abstract
Thiazolidinediones (TZDs), which are synthetic ligands for peroxisome proliferator activated receptor g (PPARg) activation, have been introduced in clinical medicine to improve insulin resistance and glycemic control in patients with type 2 diabetes. The metabolic effects of TZDs are mediated by receptor-dependent activation of the PPARg-retinoid X receptor (RXR) complex and subsequent transcriptional activation of target genes. The PPARg1 isoform is also expressed in endothelial cells, vascular smooth muscle cells, and monocytes/macrophages in the vasculature. TZDs have been shown to have anti-atherosclerotic effects on these cells in vitro, which appear to be partially independent of the PPARg-RXR-mediated transcriptional effects. Direct anti-atherosclerotic effects of TZDs include increased nitric oxide bioavailability, decreased leukocyte/endothelial cell interaction, reduced vascular smooth muscle cell migration and proliferation, and cholesterol efflux from macrophages. So far, there are no data on the effects of TZDs on cardiovascular events, but studies using surrogate markers of vascular disease provide preliminary evidence that TZDs delay progression of atherosclerosis in different patient groups. TZDs interfere with key processes in atherogenesis and may, therefore, offer additional opportunities to improve cardiovascular risk beyond treatment of glycemic control in patients with type 2 diabetes.
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Affiliation(s)
- Jeroen P H van Wijk
- University Medical Center Leiden, Department of Nephrology and Hypertension, Room C3-P, PO Box 9600, 2300 RC Leiden, The Netherlands.
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1481
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Yang K, Fan KH, Lamprecht SA, Edelmann W, Kopelovich L, Kucherlapati R, Lipkin M. Peroxisome proliferator-activated receptor gamma agonist troglitazone induces colon tumors in normal C57BL/6J mice and enhances colonic carcinogenesis in Apc1638 N/+ Mlh1+/- double mutant mice. Int J Cancer 2005; 116:495-9. [PMID: 15818612 DOI: 10.1002/ijc.21018] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of the nuclear peroxisome proliferator-activated receptor-gamma (PPAR-gamma) in colon tumorigenesis remains controversial. Notwithstanding evidence that PPAR-gamma ligands impede murine colorectal carcinogenesis, PPAR-gamma agonists have been shown to enhance in vivo tumor formation in mouse models of human colon cancer. Our study was designed to determine whether troglitazone (TGZ) induces colonic tumor formation in normal C57BL/6J mice and enhances colorectal carcinogenesis in double mutant Apc1638N/+ Mlh1+/- mice fed a standard AIN-76A diet. We report herein that not only does TGZ enhance carcinogenesis in the large intestine of mutant mice predisposed to intestinal carcinogenesis but TGZ also induces colonic tumors in normal mice without gene targeting or carcinogen administration. This observation indicates that preexisting mutational events are not necessary for induction of colonic tumors by activated PPAR-gamma in vivo.
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Affiliation(s)
- Kan Yang
- Strang Cancer Research Laboratory at The Rockefeller University, New York, NY, USA
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1482
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Abstract
Thiazolidinediones are activators of the nuclear receptor PPARgamma with proven efficacy on glucose homeostasis. However, treatment with these drugs often results in fluid retention and edema. Recent studies establish a role for PPARgamma in renal sodium reabsorption, providing a mechanism for the plasma volume expansion induced by these drugs.
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Affiliation(s)
- Bart Staels
- U545 INSERM Départment d'Athérosclérose Institut Pasteur de Lille and Faculté de pharmacie Université Lille II Lille, France
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1483
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Abstract
Cardiovascular disease (especially coronary heart disease ) is the most common complication and cause of death in patients with type 2 diabetes. CHD prevention should be the major focus in preventive care of diabetes patients. There is a solid evidence base from which to recommend aggressive control of elevated blood pressure and lipids to reduce CHD events in diabetes. Aggressive glycemic control alone will not reduce CHD events, but will prevent diabetes-specific microvascular complications. Blood pressure should be treated to a goal of at least 130/80 mm Hg, and possibly lower, using angiotensin-converting enzyme inhibitors, thiazide diuretics, or beta blockers as first-line agents. Low-density lipoprotein cholesterol should be treated with a statin to reduce the level by 30% to 40%, regardless of pretreatment level, to a goal of less than 100 mg/dL for most patients or a goal of less than 70 mg/dL in diabetes patients with CHD. Patients with high-density lipoprotein levels less than 40 mg/dL may benefit from fibrate therapy. Cigarette smoking should be actively discouraged, and prophylactic aspirin therapy should be prescribed for most patients. A regular program of physical activity and weight control should be prescribed to improve insulin sensitivity. Use of thiazolidinediones may be considered early in the course of hypoglycemic therapy, but additional research is needed to define the role of insulin sensitization as a primary means to reduce CHD risk in type 2 diabetes.
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Affiliation(s)
- James B Meigs
- General Internal Medicine Unit, Massachusetts General Hospital, 50 Staniford Street, 9th Floor, Boston, MA 02114, USA.
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1484
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1485
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Cohen SM. Effects of PPARgamma and combined agonists on the urinary tract of rats and other species. Toxicol Sci 2005; 87:322-7. [PMID: 16049269 DOI: 10.1093/toxsci/kfi266] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Samuel M Cohen
- University of Nebraska Medical Center, Department of Pathology and Microbiology, Omaha, 68198-3135, USA.
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1486
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Guan Y, Hao C, Cha DR, Rao R, Lu W, Kohan DE, Magnuson MA, Redha R, Zhang Y, Breyer MD. Thiazolidinediones expand body fluid volume through PPARgamma stimulation of ENaC-mediated renal salt absorption. Nat Med 2005; 11:861-6. [PMID: 16007095 DOI: 10.1038/nm1278] [Citation(s) in RCA: 471] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 06/24/2005] [Indexed: 12/13/2022]
Abstract
Thiazolidinediones (TZDs) are widely used to treat type 2 diabetes mellitus; however, their use is complicated by systemic fluid retention. Along the nephron, the pharmacological target of TZDs, peroxisome proliferator-activated receptor-gamma (PPARgamma, encoded by Pparg), is most abundant in the collecting duct. Here we show that mice treated with TZDs experience early weight gain from increased total body water. Weight gain was blocked by the collecting duct-specific diuretic amiloride and was also prevented by deletion of Pparg from the collecting duct, using Pparg (flox/flox) mice. Deletion of collecting duct Pparg decreased renal Na(+) avidity and increased plasma aldosterone. Treating cultured collecting ducts with TZDs increased amiloride-sensitive Na(+) absorption and Scnn1g mRNA (encoding the epithelial Na(+) channel ENaCgamma) expression through a PPARgamma-dependent pathway. These studies identify Scnn1g as a PPARgamma target gene in the collecting duct. Activation of this pathway mediates fluid retention associated with TZDs, and suggests amiloride might provide a specific therapy.
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Affiliation(s)
- YouFei Guan
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, 21st Avenue South at Garland Avenue, Nashville, Tennessee 37232, USA
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1487
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Drover VA, Abumrad NA. CD36-dependent fatty acid uptake regulates expression of peroxisome proliferator activated receptors. Biochem Soc Trans 2005; 33:311-5. [PMID: 15667335 DOI: 10.1042/bst0330311] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CD36 is an important regulator of lipid metabolism in vivo due to its role in the facilitated uptake of long-chain FAs (fatty acids). CD36-deficient mice display reduced TAG (triacylglycerol) in muscle, but elevated hepatic TAG. Also, insulin sensitivity is enhanced peripherally, while it appears impaired in the liver. Tissues such as muscle, which normally express high levels of CD36, shift to high glucose utilization in CD36 deficiency, so we hypothesized that this shift must involve adaptive changes in the PPAR (peroxisome-proliferator-activated receptor) transcription factors which regulate FA metabolism. To test this, we examined mRNA levels for the three PPAR isoforms in tissues of WT (wild-type) and CD36-deficient mice following the administration of saline, glucose or olive oil by intragastric gavage. Compared with WT mice, CD36-null mice had 5-10-fold increased PPAR mRNA in adipose tissue in the basal state, and did not exhibit diet-induced changes. Correlations between adipose PPAR mRNA abundance and plasma lipids were observed in WT mice, but not in CD36-null mice. The opposite was true for hepatic PPAR mRNA levels, which correlated with plasma FA, TAG and/or glucose only in CD36-null mice. No significant differences were observed in PPAR mRNA levels in the intestine, where CD36 does not impact on FA uptake. The data suggest that CD36 and the PPARs are components of the FA-sensing machinery to respond to changes in FA flux in a tissue-specific manner.
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Affiliation(s)
- V A Drover
- Department of Physiology and Biophysics, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
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1488
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Abstract
Osteoporosis and atherosclerosis are both widely prevalent in an ageing population, and induce serious morbidities and death. There is growing evidence that in addition to their relationship to ageing, osteoporosis and atherosclerosis are also linked by biological associations. This article reviews their clinical interrelations, discusses the basic biology of bone and the arterial wall, and presents five examples that illustrate their biological linkages. Current therapeutic approaches emerging from these linkages, including statins, bisphosphonates, and the thiazolidinediones, have dual effects on bone and the vasculature. Additional therapies derived from experimental studies that enhance bone density and reduce atherogenesis hold further promise to diminish the morbidity and mortality of osteoporosis and atherosclerosis, with attendant benefits to society.
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Affiliation(s)
- D Hamerman
- Department of Medicine and Resnick Gerontology Center, Albert Einstein College of Medicine and Montefiore Medical Center, 111 East 210th Street, Bronx, NY 10467, USA.
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1489
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Tzeng TF, Liu IM, Cheng JT. Activation of opioid mu-receptors by loperamide to improve interleukin-6-induced inhibition of insulin signals in myoblast C2C12 cells. Diabetologia 2005; 48:1386-92. [PMID: 15959754 DOI: 10.1007/s00125-005-1791-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Accepted: 02/24/2005] [Indexed: 11/26/2022]
Abstract
AIMS/HYPOTHESIS This study investigated the role of opioid mu-receptor activation in the improvement of insulin resistance. METHODS Myoblast C2C12 cells were cultured with IL-6 to induce insulin resistance. Radioactive 2-deoxyglucose (2-DG) uptake was used to evaluate the effect of loperamide on insulin-stimulated glucose utilisation. Protein expression and phosphorylation in insulin-signalling pathways were detected by immunoblotting. RESULTS The insulin-stimulated 2-DG uptake was reduced by IL-6. Loperamide reversed this uptake, and the uptake was inhibited by blockade of opioid mu-receptors. Insulin resistance induced by IL-6 was associated with impaired expression of the insulin receptor (IR), IR tyrosine autophosphorylation, IRS-1 protein content and IRS-1 tyrosine phosphorylation. Also, an attenuated p85 regulatory subunit of phosphatidylinositol 3-kinase, Akt serine phosphorylation and the protein of glucose transporter subtype 4 were observed in insulin resistance. Loperamide reversed IL-6-induced decrement of these insulin signals. CONCLUSIONS/INTERPRETATION Opioid mu-receptor activation may improve IL-6-induced insulin resistance through modulation of insulin signals to reverse the responsiveness of insulin. This provides a new target in the treatment of insulin resistance.
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Affiliation(s)
- T-F Tzeng
- Department of Internal Medicine, Pao Chien Hospital, Ping Tung City, Taiwan, Republic of China
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1490
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Bedogni G, Miglioli L, Masutti F, Tiribelli C, Marchesini G, Bellentani S. Prevalence of and risk factors for nonalcoholic fatty liver disease: the Dionysos nutrition and liver study. Hepatology 2005; 42:44-52. [PMID: 15895401 DOI: 10.1002/hep.20734] [Citation(s) in RCA: 878] [Impact Index Per Article: 46.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The prevalence of and the risk factors for fatty liver have not undergone a formal evaluation in a representative sample of the general population. We therefore performed a cross-sectional study in the town of Campogalliano (Modena, Italy), within the context of the Dionysos Project. Of 5,780 eligible persons aged 18 to 75 years, 3,345 (58%) agreed to participate in the study. Subjects with suspected liver disease (SLD), defined on the basis of elevated serum alanine aminotransferase (ALT) and gamma-glutamyl-transferase (GGT) activity, hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV)-RNA positivity, were matched with randomly selected subjects of the same age and sex without SLD. A total of 311 subjects with and 287 without SLD underwent a detailed clinical, laboratory, and anthropometrical evaluation. Fatty liver was diagnosed by ultrasonography, and alcohol intake was assessed by using a 7-day diary. Multinomial logistic regression was used to detect risk factors for normal liver versus nonalcoholic fatty liver disease (NAFLD) and for alcoholic fatty liver (AFLD) versus NAFLD. The prevalence of NAFLD was similar in subjects with and without SLD (25 vs. 20%, P = .203). At multivariable analysis, normal liver was more likely than NAFLD in older subjects and less likely in the presence of obesity, hyperglycemia, hyperinsulinemia, hypertriglyceridemia, and systolic hypertension; AFLD was more likely than NAFLD in older subjects, males, and in the presence of elevated GGT and hypertriglyceridemia, and less likely in the presence of obesity and hyperglycemia. In conclusion, NAFLD is highly prevalent in the general population, is not associated with SLD, but is associated with many features of the metabolic syndrome.
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Affiliation(s)
- Giorgio Bedogni
- Centro Studi Fegato, AREA Science Park, Basovizza, and Department of BBCM, University of Trieste, Italy
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1491
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Duffy D, Rader DJ. Drugs in development: targeting high-density lipoprotein metabolism and reverse cholesterol transport. Curr Opin Cardiol 2005; 20:301-6. [PMID: 15956827 DOI: 10.1097/01.hco.0000168532.69342.26] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review summarizes currently available therapies for raising high-density lipoprotein cholesterol (HDL-C) and expands on therapies currently in development that target high-density lipoprotein cholesterol. RECENT FINDINGS In the realm of new high-density lipoprotein-raising therapies, there is a strong focus on high-density lipoprotein metabolism and the reverse cholesterol transport pathway. Several infusions of recombinant apoA-I Milano/phospholipid complexes appeared to reduce atheroma volume as measured by intravascular ultrasound. Both intravenous and oral apoA-I mimetic peptides are in early clinical trials. Next generation PPAR-alpha agonists are more potent at high-density lipoprotein-raising than currently available fibrates, and dual PPAR-alpha/PPAR-gamma agonists are under investigation to help correct atherogenic dyslipidemia seen in many diabetics. Two small molecule inhibitors of the cholesteryl ester transfer protein have shown promise in clinical trials at substantially raising high-density lipoprotein cholesterol. SUMMARY Larger scale clinical trials, including those with additional surrogate outcome measures as well as cardiovascular event outcomes are needed to further assess the benefit of newer high-density lipoprotein-raising therapies. Additional therapeutics are currently in development that target other parts of the reverse cholesterol transport pathway and, in addition to providing new potential pharmaceuticals, will help to further elucidate the atheroprotective mechanisms of high-density lipoprotein cholesterol.
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Affiliation(s)
- Danielle Duffy
- Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
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1492
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Giorgino F, Laviola L, Leonardini A. Pathophysiology of type 2 diabetes: rationale for different oral antidiabetic treatment strategies. Diabetes Res Clin Pract 2005; 68 Suppl1:S22-9. [PMID: 15955371 DOI: 10.1016/j.diabres.2005.03.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes mellitus is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. Both insulin resistance and beta-cell failure are genetically determined to some extent; however, environmental factors contribute to exacerbate both abnormalities. Type 2 diabetic individuals are also characterised by reduced beta-cell mass likely due to increased cellular apoptosis. The early use of insulin therapy in type 2 diabetes may prove beneficial to prevent further beta-cell loss and need for exogenous insulin. Treatment options with oral agents are quite diverse, including insulin sensitizers, alpha-glucosidase inhibitors, and beta-cell secretagogues. Although in recent years the emphasis on initial therapy has been shifting from insulin secretagogues to insulin sensitizers such as metformin and thiazolidinediones, questions remain as to genetic and/or phenotypic factors may dictate a different choice of the first antidiabetic drug to be used. It is not totally clear whether monotherapy should be pursued until the maximally effective dose of a given drug or combination therapy should be used to target distinct pathogenic defects in a single patient. Individual phenotypic and genetic characterisation of the patients may help to solve this conundrum, eventually providing tailored treatment algorithms.
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Affiliation(s)
- Francesco Giorgino
- Dipartimento dell'Emergenza e dei Trapianti di Organi - Sezione di Medicina Interna, Endocrinologia e Malattie Metaboliche, Università degli Studi di Bari, Piazza Giulio Cesare 11, I-70124 Bari, Italy.
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1493
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Chen JL, Peacock E, Samady W, Turner SM, Neese RA, Hellerstein MK, Murphy EJ. Physiologic and pharmacologic factors influencing glyceroneogenic contribution to triacylglyceride glycerol measured by mass isotopomer distribution analysis. J Biol Chem 2005; 280:25396-402. [PMID: 15888453 DOI: 10.1074/jbc.m413948200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An imbalance between triacylglycerol synthesis and breakdown is necessary for the development of obesity. The direct precursor for triacylglycerol biosynthesis is alpha-glycerol phosphate, which can have glycolytic and glyceroneogenic origins. We present a technique for determining the relative glyceroneogenic contribution to triacylglyceride glycerol by labeling the glycerol moiety with 2H2O. The number of hydrogen atoms (n) incorporated from H2O into C-H bonds reflects the metabolic source of alpha-glycerol phosphate and can be calculated by combinatorial analysis of the distribution of mass isotopomers in triacylglyceride glycerol. Three physiological settings with potential effects on glyceroneogenesis and glycolysis were studied in rodents. Adipose tissue acylglyceride glycerol in mice fed a low carbohydrate diet had significantly higher values of n than in mice fed a high carbohydrate diet, suggesting an increased contribution from glyceroneogenesis of from 17 to 50% on the low carbohydrate diet. Similarly, mice administered rosiglitazone had a significant relative increase in glyceroneogenesis (from 17 to 53%), indicated by an increase in adipose acylglyceride glycerol n. Fructose infusion in overnight fasted rats rapidly lowered plasma triacylglyceride glycerol n, reflecting a decreased contribution from glyceroneogenesis (from 66 to 34%) presumably because of increased glycolytic input. In conclusion, we demonstrate that the number of C-H atoms derived from cellular H2O in triacylglyceride glycerol is an informative indicator of alpha-glycerol phosphate origin and, ultimately, triacylglycerol metabolism. Under certain physiological conditions, glyceroneogenesis can be up-regulated in adipose (e.g. low carbohydrate diet) or down-regulated in liver (e.g. fructose infusion). Additionally, stimulation of glyceroneogenesis by rosiglitazone in adipose tissue may be an important factor in the antilipolytic actions of thiazolidinediones.
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Affiliation(s)
- Jerry L Chen
- Department of Nutritional Sciences & Toxicology, University of California-Berkeley, Berkeley, California 94720, USA
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1494
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Abstract
Type 2 diabetes mellitus is a progressive and complex disorder that is difficult to treat effectively in the long term. The majority of patients are overweight or obese at diagnosis and will be unable to achieve or sustain near normoglycaemia without oral antidiabetic agents; a sizeable proportion of patients will eventually require insulin therapy to maintain long-term glycaemic control, either as monotherapy or in conjunction with oral antidiabetic therapy. The frequent need for escalating therapy is held to reflect progressive loss of islet beta-cell function, usually in the presence of obesity-related insulin resistance. Today's clinicians are presented with an extensive range of oral antidiabetic drugs for type 2 diabetes. The main classes are heterogeneous in their modes of action, safety profiles and tolerability. These main classes include agents that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). The UKPDS (United Kingdom Prospective Diabetes Study) demonstrated the benefits of intensified glycaemic control on microvascular complications in newly diagnosed patients with type 2 diabetes. However, the picture was less clearcut with regard to macrovascular disease, with neither sulphonylureas nor insulin significantly reducing cardiovascular events. The impact of oral antidiabetic agents on atherosclerosis--beyond expected effects on glycaemic control--is an increasingly important consideration. In the UKPDS, overweight and obese patients randomised to initial monotherapy with metformin experienced significant reductions in myocardial infarction and diabetes-related deaths. Metformin does not promote weight gain and has beneficial effects on several cardiovascular risk factors. Accordingly, metformin is widely regarded as the drug of choice for most patients with type 2 diabetes. Concern about cardiovascular safety of sulphonylureas has largely dissipated with generally reassuring results from clinical trials, including the UKPDS. Encouragingly, the recent Steno-2 Study showed that intensive target-driven, multifactorial approach to management, based around a sulphonylurea, reduced the risk of both micro- and macrovascular complications in high-risk patients. Theoretical advantages of selectively targeting postprandial hyperglycaemia require confirmation in clinical trials of drugs with preferential effects on this facet of hyperglycaemia are currently in progress. The insulin-sensitising thiazolidinedione class of antidiabetic agents has potentially advantageous effects on multiple components of the metabolic syndrome; the results of clinical trials with cardiovascular endpoints are awaited. The selection of initial monotherapy is based on a clinical and biochemical assessment of the patient, safety considerations being paramount. In some circumstances, for example pregnancy or severe hepatic or renal impairment, insulin may be the treatment of choice when nonpharmacological measures prove inadequate. Insulin is also required for metabolic decompensation, that is, incipient or actual diabetic ketoacidosis, or non-ketotic hyperosmolar hyperglycaemia. Certain comorbidities, for example presentation with myocardial infarction during other acute intercurrent illness, may make insulin the best option. Oral antidiabetic agents should be initiated at a low dose and titrated up according to glycaemic response, as judged by measurement of glycosylated haemoglobin (HbA1c) concentration, supplemented in some patients by self monitoring of capillary blood glucose. The average glucose-lowering effect of the major classes of oral antidiabetic agents is broadly similar (averaging a 1-2% reduction in HbA1c), alpha-glucosidase inhibitors being rather less effective. Tailoring the treatment to the individual patient is an important principle. Doses are gradually titrated up according to response. However, the maximal glucose-lowering action for sulphonylureas is usually attained at appreciably lower doses (approximately 50%) than the manufacturers' recommended daily maximum. Combinations of certain agents, for example a secretagogue plus a biguanide or a thiazolidinedione, are logical and widely used, and combination preparations are now available in some countries. While the benefits of metformin added to a sulphonylurea were initially less favourable in the UKPDS, longer-term data have allayed concern. When considering long-term therapy, issues such as tolerability and convenience are important additional considerations. Neither sulphonylureas nor biguanides are able to appreciably alter the rate of progression of hyperglycaemia in patients with type 2 diabetes. Preliminary data suggesting that thiazolidinediones may provide better long-term glycaemic stability are currently being tested in clinical trials; current evidence, while encouraging, is not conclusive. Delayed progression from glucose intolerance to type 2 diabetes in high-risk individuals with glucose intolerance has been demonstrated with troglitazone, metformin and acarbose. However, intensive lifestyle intervention can be more effective than drug therapy, at least in the setting of interventional clinical trials. No antidiabetic drugs are presently licensed for use in prediabetic individuals.
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Affiliation(s)
- Andrew J Krentz
- Southampton University Hospitals NHS Trust, Southampton, UK.
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1495
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Affiliation(s)
- Elaine Cochran
- Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases/NIH, 9000 Rockville Pike, Bldg. 10, CRC 6-5940, Bethesda, MD 20892, USA.
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1496
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Abstract
The three peroxisome-proliferator-activated receptor (PPAR) subtypes, PPAR-gamma, PPAR-alpha and PPAR-delta, are nuclear receptors that have been the focus of extensive research during the past decade. These receptors function as lipid sensors that coordinately regulate the expression of large gene arrays and, thereby, modulate important metabolic events. They are also the targets of drugs that are effective in the treatment of metabolic disorders (type 2 diabetes mellitus and atherosclerosis) that afflict industrialized societies at epidemic levels. Ongoing research indicates that modulation of PPAR activity might be an effective therapy for additional maladies associated with the metabolic syndrome, including obesity. Novel PPAR ligands are now being developed that possess broader efficacies and improved tolerability compared with currently available therapeutic agents.
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Affiliation(s)
- Joel P Berger
- Department of Metabolic Disorders, Merck Research Laboratories, Rahway, NJ 07065, USA.
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1497
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BAILEY C. Hemostatic abnormalities associated with obesity and the metabolic syndrome. J Thromb Haemost 2005. [DOI: 10.1111/j.1538-7836.2005.01282.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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1498
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Savage DB, Petersen KF, Shulman GI. Mechanisms of insulin resistance in humans and possible links with inflammation. Hypertension 2005; 45:828-33. [PMID: 15824195 DOI: 10.1161/01.hyp.0000163475.04421.e4] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Insulin resistance is a major player in the pathogenesis of the metabolic syndrome and type 2 diabetes, and yet, the mechanisms responsible for it remain poorly understood. Magnetic resonance spectroscopy studies in humans suggest that a defect in insulin-stimulated glucose transport in skeletal muscle is the primary metabolic abnormality in insulin-resistant type 2 diabetics. Fatty acids appear to cause this defect in glucose transport by inhibiting insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and IRS-1 associated phosphatidylinositol 3-kinase activity. A number of different metabolic abnormalities may increase intramyocellular/intrahepatic fatty acid metabolites; these include increased fat delivery to muscle/liver as a consequence of either excess energy intake or defects in adipocyte fat metabolism and acquired or inherited defects in mitochondrial fatty acid oxidation. Understanding the molecular/biochemical defects responsible for insulin resistance is beginning to unveil novel therapeutic targets for treatment of the metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- David B Savage
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Conn 06510, USA
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1499
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Abstract
Type 2 diabetes mellitus has become an epidemic, and virtually no physician is without patients who have the disease. Whereas insulin insensitivity is an early phenomenon partly related to obesity, pancreas beta-cell function declines gradually over time already before the onset of clinical hyperglycaemia. Several mechanisms have been proposed, including increased non-esterified fatty acids, inflammatory cytokines, adipokines, and mitochondrial dysfunction for insulin resistance, and glucotoxicity, lipotoxicity, and amyloid formation for beta-cell dysfunction. Moreover, the disease has a strong genetic component, but only a handful of genes have been identified so far: genes for calpain 10, potassium inward-rectifier 6.2, peroxisome proliferator-activated receptor gamma, insulin receptor substrate-1, and others. Management includes not only diet and exercise, but also combinations of anti-hyperglycaemic drug treatment with lipid-lowering, antihypertensive, and anti platelet therapy.
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Affiliation(s)
- Michael Stumvoll
- Third Medical Department, University of Leipzig, Leipzig, Germany
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1500
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Heneka MT, Sastre M, Dumitrescu-Ozimek L, Hanke A, Dewachter I, Kuiperi C, O'Banion K, Klockgether T, Van Leuven F, Landreth GE. Acute treatment with the PPARγ agonist pioglitazone and ibuprofen reduces glial inflammation and Aβ1–42 levels in APPV717I transgenic mice. Brain 2005; 128:1442-53. [PMID: 15817521 DOI: 10.1093/brain/awh452] [Citation(s) in RCA: 424] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neuritic plaques in the brain of Alzheimer's disease patients are characterized by beta-amyloid deposits associated with a glia-mediated inflammatory response. Non-steroidal anti-inflammatory drug (NSAID) therapy reduces Alzheimer's disease risk and ameliorates microglial reactivity in Alzheimer's disease brains; however, the molecular mechanisms subserving this effect are not yet clear. Since several NSAIDs bind to and activate the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma) which acts to inhibit the expression of proinflammatory genes, this receptor appears a good candidate to mediate the observed anti-inflammatory effects. Recent data in vitro suggested that NSAIDs negatively regulate microglial activation and immunostimulated amyloid precursor protein processing via PPARgamma activation. We report that an acute 7 day oral treatment of 10-month-old APPV717I mice with the PPARgamma agonist pioglitazone or the NSAID ibuprofen resulted in a reduction in the number of activated microglia and reactive astrocytes in the hippocampus and cortex. Drug treatment reduced the expression of the proinflammatory enzymes cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS). In parallel to the suppression of inflammatory markers, pioglitazone and ibuprofen treatment decreased beta-secretase-1 (BACE1) mRNA and protein levels. Importantly, we observed a significant reduction of the total area and staining intensity of Abeta1-42-positive amyloid deposits in the hippocampus and cortex. Additionally, animals treated with pioglitazone revealed a 27% reduction in the levels of soluble Abeta1-42 peptide. These findings demonstrate that anti-inflammatory drugs can act rapidly to inhibit inflammatory responses in the brain and negatively modulate amyloidogenesis.
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