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Effects of short-term caloric restriction on circulating free IGF-I, acid-labile subunit, IGF-binding proteins (IGFBPs)-1-4, and IGFBPs-1-3 protease activity in obese subjects.
Rasmussen, MH, Juul, A, Kjems, LL, Hilsted, J
European journal of endocrinology. 2006;(4):575-81
Abstract
OBJECTIVE Decreased levels of GH and total IGF-I have been reported in obesity. It has been hypothesized that increased free (biologically active) IGF-I levels generated from IGF-binding protein (IGFBP) protease activity could be the mechanism for the low GH release in dieting obese subjects. However, no published data exist on free IGF-I levels, acid labile subunit (ALS), or IGFBP protease activity in relation to GH release during a hypocaloric diet. The main purpose of this study was to determine free IGF-I, ALS, IGFBPs-1-4, and IGFBPs-1-3 protease activity in relation to 24-h GH release before and after a short-term very low-calorie diet (VLCD). DESIGN Six obese subjects before weight loss, five after an average weight loss of 36.1 kg, and five age-and sex-matched lean controls underwent a 4-day VLCD. All subjects were studied on two occasions, once during normal basic diet and again during the last day of the VLCD (1.6 MJ). METHODS Free IGF-I was determined by a non-competitive immunoradiometric assay. RESULTS Free IGF-I levels decreased in concert with increased ALS and unchanged blunted GH release after a VLCD in the obese subjects. IGFBPs-1-3 proteolytic activity was found to be unchanged by hypocaloric diet in all groups. CONCLUSIONS We conclude that free IGF-I decreases after a short-term hypocaloric diet in obese subjects with no concomitant change in 24-h GH release. Circulating free IGF-I per se cannot be the main mechanism of the attenuated GH release in dieting obese subjects.
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Altered osteoprotegerin/RANKL ratio and low bone mineral density in celiac patients on long-term treatment with gluten-free diet.
Fiore, CE, Pennisi, P, Ferro, G, Ximenes, B, Privitelli, L, Mangiafico, RA, Santoro, F, Parisi, N, Lombardo, T
Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme. 2006;(6):417-22
Abstract
Skeletal demineralization and mineral metabolism derangement are well-recognized features of untreated celiac disease (CD). Although treatment with a gluten-free diet appears to prevent bone loss while correcting skeletal demineralization in childhood, there is evidence that bone mineral density does not return to normal in celiacs diagnosed in adulthood. Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor family, and ligand of receptor activator of NFkB (RANKL) are involved in the process of bone turnover and have been implicated in the pathogenesis of osteoporosis and other metabolic bone diseases. We measured OPG, RANKL, bone mineral density (BMD), and biochemical markers of bone turnover in 32 adult female premenopausal celiac patients on a gluten-free diet, and thirty age-matched healthy women. We correlated the OPG/RANKL ratio with the severity of bone loss. Celiac patients had a mean BMD lower than controls in lumbar spine and in the femoral neck. Serum levels of bone alkaline phosphatase (BAP, marker of bone formation), and urinary excretion of telopeptides of type I collagen (a marker of bone resorption) were significantly higher than in controls. Serum OPG and RANKL levels were significantly higher in CD patients than in controls, while the OPG/RANKL ratio was significantly lower in CD patients than in controls and was positively correlated with BMD at the spine. The role of elevated OPG in CD patients is unclear, but it might represent a compensatory mechanism against other factors that promote bone damage. Further studies are required to assess a possible therapeutic potential of osteoprotegerin in optimally treated celiacs with persistent osteopenia.
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Effects of the cholesteryl ester transfer protein inhibitor torcetrapib on apolipoprotein B100 metabolism in humans.
Millar, JS, Brousseau, ME, Diffenderfer, MR, Barrett, PH, Welty, FK, Faruqi, A, Wolfe, ML, Nartsupha, C, Digenio, AG, Mancuso, JP, et al
Arteriosclerosis, thrombosis, and vascular biology. 2006;(6):1350-6
Abstract
OBJECTIVE Cholesteryl ester transfer protein (CETP) inhibition with torcetrapib not only increases high-density lipoprotein cholesterol levels but also significantly reduces plasma triglyceride, low-density lipoprotein (LDL) cholesterol, and apolipoprotein B (apoB) levels. The goal of the present study was to define the kinetic mechanism(s) by which CETP inhibition reduces levels of apoB-containing lipoproteins. METHODS AND RESULTS Nineteen subjects, 9 of whom were pretreated with 20 mg atorvastatin, received placebo for 4 weeks, followed by 120 mg torcetrapib once daily for 4 weeks. Six subjects in the nonatorvastatin group received 120 mg torcetrapib twice daily for an additional 4 weeks. After each phase, subjects underwent a primed-constant infusion of deuterated leucine to endogenously label newly synthesized apoB to determine very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL) and LDL apoB100 production, and fractional catabolic rates (FCRs). Once-daily 120 mg torcetrapib significantly reduced VLDL, IDL, and LDL apoB100 pool sizes by enhancing the FCR of apoB100 within each fraction. On a background of atorvastatin, 120 mg torcetrapib significantly reduced VLDL, IDL, and LDL apoB100 pool sizes. The reduction in VLDL apoB100 was associated with an enhanced apoB100 FCR, whereas the decreases in IDL and LDL apoB100 were associated with reduced apoB100 production. CONCLUSIONS These data indicate that when used alone, torcetrapib reduces VLDL, IDL, and LDL apoB100 levels primarily by increasing the rate of apoB100 clearance. In contrast, when added to atorvastatin treatment, torcetrapib reduces apoB100 levels mainly by enhancing VLDL apoB100 clearance and reducing production of IDL and LDL apoB100.
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[Polymorphisms of myocilin and optineurin in primary open angle glaucoma patients].
Yao, HY, Cheng, CY, Fan, BJ, Tam, OS, Tham, CY, Wang, DY, Lam, SC, Pang, CP
Zhonghua yi xue za zhi. 2006;(8):554-9
Abstract
OBJECTIVE To detect the single nucleotide polymorphisms (SNPs) of the myocilin (MYOC) and optineurin (OPTN) genes, and to investigate their associations with high tension glaucoma (HTG) and normal tension glaucoma (NTG). METHODS SNPs were detected using polymerase chain reaction (PCR), followed by conformation sensitive gel electrophoresis (CSGE) and fluorescent labeling automated DNA sequencing among 94 unrelated patients with HTG, 48 unrelated patients with NTG, and 77 unrelated control subjects. RESULTS Fourteen MYOC sequence alterations were identified, five of them: V53A, I304I, T347T, 1-126T > C, and IVS2 + 172C > A, were novel. Among them, V53A was for the first time found in primary open angle glaucoma (POAG) patient. R76K usually occurred with the promoter polymorphism 1-83G > A. No sequence alterations in the MYOC gene showed significant differences among the HTG, NTG and control subjects (all P > 0.05). A total of 12 sequence alterations were identified in the OPTN gene, and three of them: V161M, I407T and L211L, were novel. Among them, I407T and L211L were found only in the HTG patients. The allele and genotype frequencies of T34T in the NTG patients were significantly higher than those of the controls (P = 0.001 and 0.004 respectively). In HTG, only the allele frequency of T34T was 24% (23/96), significantly higher than those of the NTG group (16.5%, 31/188) and the control group (9.1%, 14/154) (both P < 0.05). In addition, IVS8 + 20G > A was found only in the HTG (3.1%, 3/96) and NTG patients (3.7%, 7/188), and had significantly higher frequencies in the HTG and NTG patients when compared with the controls (P = 0.016 and 0.014, and P = 0.027 and 0.026). CONCLUSION Polymorphisms in the MYOC and OPTN genes are associated with POAG in Chinese people. Moreover, sequence alterations not causing amino acid changes may play a role in the pathogenesis of POAG.
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Effects of cholesteryl ester transfer protein inhibition on high-density lipoprotein subspecies, apolipoprotein A-I metabolism, and fecal sterol excretion.
Brousseau, ME, Diffenderfer, MR, Millar, JS, Nartsupha, C, Asztalos, BF, Welty, FK, Wolfe, ML, Rudling, M, Björkhem, I, Angelin, B, et al
Arteriosclerosis, thrombosis, and vascular biology. 2005;(5):1057-64
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Abstract
OBJECTIVE Pharmacological inhibition of the cholesteryl ester transfer protein (CETP) in humans increases high-density lipoprotein (HDL) cholesterol (HDL-C) levels; however, its effects on apolipoprotein A-I (apoA-I) containing HDL subspecies, apoA-I turnover, and markers of reverse cholesterol transport are unknown. The present study was designed to address these issues. METHODS AND RESULTS Nineteen subjects, 9 of whom were taking 20 mg of atorvastatin for hypercholesterolemia, received placebo for 4 weeks, followed by the CETP inhibitor torcetrapib (120 mg QD) for 4 weeks. In 6 subjects from the nonatorvastatin cohort, the everyday regimen was followed by a 4-week period of torcetrapib (120 mg BID). At the end of each phase, subjects underwent a primed-constant infusion of (5,5,5-2H3)-L-leucine to determine the kinetics of HDL apoA-I. The lipid data in this study have been reported previously. Relative to placebo, 120 mg daily torcetrapib increased the amount of apoA-I in alpha1-migrating HDL in the atorvastatin (136%; P<0.001) and nonatorvastatin (153%; P<0.01) cohorts, whereas an increase of 382% (P<0.01) was observed in the 120 mg twice daily group. HDL apoA-I pool size increased by 8+/-15% in the atorvastatin cohort (P=0.16) and by 16+/-7% (P<0.0001) and 34+/-8% (P<0.0001) in the nonatorvastatin 120 mg QD and BID cohorts, respectively. These changes were attributable to reductions in HDL apoA-I fractional catabolic rate (FCR), with torcetrapib reducing HDL apoA-I FCR by 7% (P=0.10) in the atorvastatin cohort, by 8% (P<0.001) in the nonatorvastatin 120 mg QD cohort, and by 21% (P<0.01) in the nonatorvastatin 120 mg BID cohort. Torcetrapib did not affect HDL apoA-I production rate. In addition, torcetrapib did not significantly change serum markers of cholesterol or bile acid synthesis or fecal sterol excretion. CONCLUSIONS These data indicate that partial inhibition of CETP via torcetrapib in patients with low HDL-C: (1) normalizes apoA-I levels within alpha1-migrating HDL, (2) increases plasma concentrations of HDL apoA-I by delaying apoA-I catabolism, and (3) does not significantly influence fecal sterol excretion.
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Clinical significance of serum oxidized low-density lipoprotein/beta2-glycoprotein I complexes in patients with chronic renal diseases.
Kasahara, J, Kobayashi, K, Maeshima, Y, Yamasaki, Y, Yasuda, T, Matsuura, E, Makino, H
Nephron. Clinical practice. 2004;(1):c15-24
Abstract
BACKGROUND Peroxidation of low-density lipoprotein (LDL) plays an important role in the development of dyslipidemias associated with the progression of chronic renal disorders. We recently reported [J Lipid Res 2001;42:697, 2002;43:1486, 2003;44:716] that oxidized LDL (oxLDL) interacts with an endogenous plasma protein, beta2-glycoprotein I (beta2GPI), via specific ligands. In the present study, the prevalence and clinical significance of oxLDL/beta2GPI complexes were evaluated in patients with chronic renal disorders. METHODS Serum levels of oxLDL/beta(2)GPI complexes were measured by ELISA in patients with chronic renal disease and their association with clinical manifestations was assessed. RESULTS The serum levels of oxLDL/beta2GPI complexes were significantly higher in patients with chronic renal failure (CRF), chronic nephritis (CN) and diabetes mellitus than those in healthy individuals. The presence of complexes in patients with CN was significantly associated with high dietary protein and sodium chloride intake, but not with lipid metabolic parameters. Malondialdehyde-modified LDL was significantly associated with total cholesterol and LDL cholesterol in all patient groups, but did not correlate with renal function parameters. CONCLUSIONS Serum oxLDL/beta2GPI complexes, generated by oxidative stress and associated with high dietary protein and salt intake, might be a novel risk factor and a diagnostic marker for the development of chronic renal diseases, especially IgA nephropathy.
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[Genetic variation of the cholesterol ester transfer protein gene and the prevalence of coronary artery disease. The AtheroGene case control study].
Blankenberg, S, Tiret, L, Bickel, C, Schlitt, A, Jungmair, W, Genth-Zotz, S, Lubos, E, Espinola-Klein, C, Rupprecht, HJ
Zeitschrift fur Kardiologie. 2004;:IV16-23
Abstract
BACKGROUND Various functional polymorphisms of the cholesteryl ester transfer protein ( CETP) gene influence CETP activity and the concentration of high-density lipoprotein (HDL) cholesterol. Beside other functional variants mainly the promoter polymorphism CETP/C-629A is currently discussed as a risk factor of coronary artery disease (CAD). We evaluated in a large case-control study the impact of various CETP genotypes and haplotypes on HDL concentration and the prevalence of CAD. METHODS AND RESULTS In 1214 patients with documented CAD as well as 754 population controls we determined the CETP/C-629A, TaqIB, I405V, R451Q, and A373P polymorphisms. All genotypes have an impact on the HDL concentration; univariate genotype and haplotype analyses demonstrate a significant effect of A-allel carriers on the elevation of HDL concentration. In addition, among all genotypes determined, the C-629A polymorphism is associated with the prevalence of CAD in a codominant fashion. Homozygous A-allel carriers reveal a relative risk of 0.6 (95% CI 0.44-0.82; P = 0.005) compared to the wild type. Adjustment for classical risk factors did not alter this association significantly, whereas after controlling for HDL concentration no independent significance between CETP/C-629A genotype and prevalence of CAD was observed anymore. CONCLUSION CETP genotypes have an significant but moderate impact on systemic HDL-cholesterol concentration. The A-allel of the CETP/C-629A polymorphism is associated with a reduced CAD risk. This risk reduction is probably mediated by elevated HDL-concentration. Whether genotyping of the CETP/C-629A polymorphism provides information over and above that obtained by HDL-cholesterol measurement has to be further investigated in various prospective studies.