Fatty acid derivatised analogues of glucose-dependent insulinotropic polypeptide with improved antihyperglycaemic and insulinotropic properties

C-terminal acylation of Lys(37) with myristic (MYR; tetradecanoic acid), palmitic (PAL; hexadecanoic acid) and stearic (octadecanoic acid) fatty acids with or without N-terminal acetylation was employed to develop long-acting analogues of the glucoregulatory hormone, glucose-dependent insulinotropic polypeptide (GIP). All GIP analogues exhibited resistance to dipeptidylpeptidase-IV (DPP-IV) and significantly improved in vitro cAMP production and insulin secretion. Administration of GIP analogues to ob/ob mice significantly lowered plasma glucose-GIP(Lys(37)MYR), N-AcGIP(Lys(37)MYR) and GIP(Lys(37)PAL) increased plasma insulin concentrations. GIP(Lys(37)MYR) and N-AcGIP(Lys(37)MYR) elicited protracted glucose-lowering effects when administered 24h prior to an intraperitoneal glucose load. Daily administration of GIP(Lys(37)MYR) and N-AcGIP(Lys(37)MYR) to ob/ob mice for 24 days decreased glucose and significantly improved plasma insulin, glucose tolerance and beta-cell glucose responsiveness. Insulin sensitivity, pancreatic insulin content and triglyceride levels were not changed. These data demonstrate that C-terminal acylation particularly with myristic acid provides a class of stable, longer-acting forms of GIP for further evaluation in diabetes therapy.

Signaling pathways initiated by beta-hydroxy-beta-methylbutyrate to attenuate the depression of protein synthesis in skeletal muscle in response to cachectic stimuli

To investigate the mechanism by which beta-hydroxy-beta-methylbutyrate (HMB) attenuates the depression of protein synthesis in the skeletal muscle of cachectic mice, a study has been carried out in murine myotubes in the presence of proteolysis-inducing factor (PIF). PIF inhibited protein synthesis by 50% within 4 h, and this was effectively attenuated by HMB (25-50 muM). HMB (50 muM) alone stimulated protein synthesis, and this was attenuated by rapamycin (27 nM), an inhibitor of mammalian target of rapamycin (mTOR). Further evidence for an involvement of this pathway was shown by an increased phosphorylation of mTOR, the 70-kDa ribosomal S6 kinase (p70(S6k)), and initiation factor 4E-binding protein (4E-BP1) and an increased association of eukaryotic initiation factor 2 (eIF4E) with eIF4G. PIF alone induced a transient (1-2 h) stimulation of phosphorylation of mTOR and p70(S6k). However, in the presence of HMB, phosphorylation of mTOR, p70(S6k), and 4E-BP1 was increased, and inactive 4E-BP1-eIF4E complex was reduced, whereas the active eIF4G.eIF4E complex was increased, suggesting continual stimulation of protein synthesis. HMB alone reduced phosphorylation of elongation factor 2, but this effect was not seen in the presence of PIF. PIF induced autophosphorylation of the double-strand RNA-dependent protein kinase (PKR), leading to phosphorylation of eIF2 on the alpha-subunit, which would inhibit protein synthesis. However, in the presence of HMB, phosphorylation of PKR and eIF2alpha was attenuated, and this was also observed in skeletal muscle of cachectic mice administered HMB (0.25 g/kg). These results suggest that HMB attenuates the depression of protein synthesis by PIF in myotubes through multiple mechanisms.

Soft [beta]-adrenoceptor agonists for topical use in psoriasis

Psoriasis is characterised by epidermal proliferation and inflammation resulting in the appearance of elevated erythematous plaques. The ratio of c~AMP/c~GMP is decreased in psoriatic skin and when the epidermal cell surface receptors are stimulated by β-adrenergic agonists, intracellular ATP is transformed into c-AMP, thus restoring the c~AMP/c~GMP levels. This thesis describes a series of β-adrenoceptor agonists for topical delivery based upon the soft-drug approach. Soft drugs are defined as biologically active, therapeutically useful chemical compounds (drugs) characterised by a predictable and controllable In vivo destruction (metabolism) to non-toxic moieties. after they achieve their therapeutic role, The N-substituent can accommodate a broad range of structures and here the alkoxycarbonylethyl group has been used to provide metabolic susceptability. The increased polarity of the dihydroxy acid, expected after metabolic conversion of the soft~drug, ethyl N-[2'-(3',4'-dihydroxyphenyl)-2'-hydroxyethyl]-3- aminopropionate, should eliminate agonist activity. Further. to prevent oxidation and enhance topical delivery, the catechol hydroxyl groups have been esterified to produce a pro-soft-drug which generates the soft-drug in enzymic systems. The chemical hydrolysis of the pro-soft-drug proceeded via the formation of the dlpivaloyloxy acid and it failed to generate the active dihydroxy ester soft-drug. In contrast, in the presence of porcine liver carboxyesterase, the hydrolysis of the pro-soft drug proceeded via the formation of the required active soft-drug. This compound, thus, has the appropnate kinetic features to enable it to be evaluated further as a drug for the treatment of psoriasis. The pH rate-profile for the hydrolysis of soft-drug indicated a maximum stability at pH ∼ 4.0. The individual rate constants for the degradation and the pKa were analysed by nonlinear regression. The pKa of 7.40 is in excellent agreement with that determined by direct titration (7.43) and indicates that satisfactory convergence was achieved. The soft-drug was poorly transported across a silicone membrane; it was also air-sensitive due to oxidation of the catechol group. The transport of the pro-soft-drug was more efficient and, over the donor pH range 3-8, increased with pH. At lower values, the largely protonated species was not transported. However, above pH 7. chemical degradation was rapid so that a donor pH of 5-6 was optimum. The β-adrenergic agonist activity of these compounds was tested in vitro by measuring chronotropic and inotropic responses in the guinea pig atria and relaxation of guinea pig trachea precontracted with acetylcholine (10-3 M). The soft~drug was a full agonist on the tracheal preparation but was less potent than isoprenaline. Responses of the soft~drug were competitively antagonised by propranolol (10-6 M). The soft~drug produced an increase in force and rate of the isolated atrial preparatIon. The propyl analogue was equally potent with ED50 of 6.52 x 10-7 M. In contrast, at equivalent doses, the dihydroxy acid showed no activity; only a marginal effect was observed on the tracheal preparation. For the pro~soft-drug, responses were of slow onset, in both preparations, with a slowly developing relaxatlon of the tracheal preparatlon at high concentrations (10-5 M). This is consistent with in vitro results where the dipivaloyl groups are hydrolysed more readily than the ethyl ester to gIve the active soft-drug. These results confirm the validity tif the pro-soft-drug approach to the deUvery of β-adrenoceptor agonists.

Improving the function of islet and beta-cell grafts

Background: Human islet transplantation would offer a less invasive and more physiological alternative than whole pancreas transplantation and insulin injections respectively for the treatment of diabetes mellitus if islet graft survival can be improved. Initial recipient post-transplant insulin independence declines to <10% after 5 years. Factors contributing to graft failure include enzymatic disruption of the islet microenvironment during isolation, diabetogenic effects of immunosuppressants and metabolic stress resulting from slow revascularisation. Aims: To investigate the effect of co-culture in both static (SC) and rotational culture (RC) of BRINBDII beta-cells (Dl1) and human umbilical vein endothelial cells (HUVEC) on Dl1 insulin secretion; and the effect of a thiazolidinedione (TZD) on DII function and HUVEC proliferation. To assess the effect of culture media, SC, RC and a TZD on human islet morphology, insulin secretion and VEGF production. To initiate in vivo protocol development for assessment of revascularisation of human islet grafts. Methods: D11 cells were cultured +/-TZD and co-cultured with HUVEC +/-TZD in SC and RC. Dl1 insulin secretion was induced by static incubation with low glucose (1.67mM), high glucose (l6.7mM: and high glucose with 10mM theophylline (G+T) and determined by ELISA. HUVEC were cultured +/-TZD in SC and RC and proliferation was assessed by ATP luminescence assay and VEGF ELISA. D II and HUVEC morphology was determined by immunocytochemistry. Human islets were cultured in SC and RC in various media +/-TZD. Insulin secretion was determined as above and VEGF production by fluorescence immunocytochemistry (FI) and ELISA. Revascularisation of islet grafts was assessed by vascular corrosion cast and FI. Results: Dll cultures showed significantly increased insulin secretion in response to 16.7mM and G+T over basal; this was enhanced by RC and further improved by adding 10mM TZD. Untreated Dll/HUVEC co-cultures displayed significantly increased insulin secretion in response to 16.7mM and G+T over basal, again enhanced by RC and improved with 10mM TZD. 10mM TZD significantly increased HUVEC proliferation over control. Human islets maintained in medium 199 (mI99) in SC and RC exhibited comparable maintenance of morphology and insulin secretory profiles compared to islets maintained in RPMI, endothelial growth media and dedicated islet medium Miami# I. All cultures showed significantly increased insulin secretion in response to 16.7mM and G+T over basal; this was enhanced by RC and in certain instances further improved by adding 25mM TZD. TZD increased VEGF production and release as determined by ELISA. Post-implant vascular corrosion casts of mouse kidneys analysed by x-ray micro tomography indicates a possible TZD enhancement of microvessel growth via VEGF upregulation. Conclusions: D II /HUVEC co-culture in SC or RC does not alter the morphology of either cell type and supports D 11 function. TZD improves 0 I I and D I I/HUVEC SC and RC co-culture insulin secretion while increasing HUVEC proliferation. Human islet RC supports islet functional viability and structural integrity compared to SC while the addition of TZD occasionally further improves secretagogue induced insulin secretion. Expensive, 'dedicated' islet media showed no advantage over ml99 in terms of maintaining islet morphology or function. TZD upregulates VEGF in islets as shown by ELISA and suggested by x-ray micro tomography analysis of vascular corrosion casts. Maintenance of islets in RC and treatment with TZD prior to transplant may improve the functional viability and revascularisation rate of islet grafts.

Visfatin regulates insulin secretion, insulin receptor signalling and mRNA expression of diabetes-related genes in mouse pancreatic beta-cells

The role of the adipocyte-derived factor visfatin in metabolism remains controversial, although some pancreatic ß-cell-specific effects have been reported. This study investigated the effects of visfatin upon insulin secretion, insulin receptor activation and mRNA expression of key diabetes-related genes in clonal mouse pancreatic ß-cells. ß-TC6 cells were cultured in RPMI 1640 and were subsequently treated with recombinant visfatin. One-hour static insulin secretion was measured by ELISA. Phospho-specific ELISA and western blotting were used to detect insulin receptor activation. Real-time SYBR Green PCR array technology was used to measure the expression of 84 diabetes-related genes in both treatment and control cells. Incubation with visfatin caused significant changes in the mRNA expression of several key diabetes-related genes, including marked up-regulation of insulin (9-fold increase), hepatocyte nuclear factor (HNF)1ß (32-fold increase), HNF4a (16-fold increase) and nuclear factor ?B (40-fold increase). Significant down-regulation was seen in angiotensin-converting enzyme (-3.73-fold) and UCP2 (-1.3-fold). Visfatin also caused a significant 46% increase in insulin secretion compared to control (P<0.003) at low glucose, and this increase was blocked by co-incubation with the specific nicotinamide phosphoribosyltransferase inhibitor FK866. Both visfatin and nicotinamide mononucleotide induced activation of both insulin receptor and extracellular signal-regulated kinase (ERK)1/2, with visfatin-induced insulin receptor/ERK1/2 activation being inhibited by FK866. We conclude that visfatin can significantly regulate insulin secretion, insulin receptor phosphorylation and intracellular signalling and the expression of a number of ß-cell function-associated genes in mouse ß-cells.

Oscillatory beta activity mediates neuroplastic effects of motor cortex stimulation in humans

Continuous theta burst stimulation (cTBS) is a repetitive transcranial magnetic stimulation protocol that can inhibithumanmotor cortex (M1) excitability and impair movement for ≤1 h. While offering valuable insights into brain function and potential therapeutic benefits, these neuroplastic effects are highly variable between individuals. The source of this variability, and the electrophysiological mechanisms underlying the inhibitory after-effects, are largely unknown. In this regard, oscillatory activity at beta frequency (15-35 Hz) is of particular interest as it is elevated in motor disorders such as Parkinson's disease and modulated during the generation of movements. Here, we used a source-level magnetoencephalography approach to investigate the hypothesis that the presence of neuroplastic effects following cTBS is associated with concurrent changes in oscillatory M1 beta activity. M1 cortices were localized with a synthetic aperture magnetometry beamforming analysis of visually cued index finger movements. Virtual electrode analysis was used to reconstruct the spontaneous and movement-related oscillatory activity in bilateral M1 cortices, before and from 10 to 45 min after cTBS. We demonstrate that 40 s of cTBS applied over left M1 reduced corticospinal excitability in the right index finger of 8/16 participants. In these responder participants only, cTBS increased the power of the spontaneous beta oscillations in stimulated M1 and delayed reaction times in the contralateral index finger. No further changes were observed in the latency or power of movement-related beta oscillations. These data provide insights into the electrophysiological mechanisms underlying cTBS-mediated impairment of motor function and demonstrate the association between spontaneous oscillatory beta activity in M1 and the inhibition of motor function. © 2013 the authors.

Novel dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1(7-36)amide have preserved biological activities in vitro conferring improved glucose-lowering action in vivo

Although the incretin hormone glucagon-like peptide-1 (GLP-1) is a potent stimulator of insulin release, its rapid degradation in vivo by the enzyme dipeptidyl peptidase IV (DPP IV) greatly limits its potential for treatment of type 2 diabetes. Here, we report two novel Ala8-substituted analogues of GLP-1, (Abu8)GLP-1 and (Val8)GLP-1 which were completely resistant to inactivation by DPP IV or human plasma. (Abu8)GLP-1 and (Val8)GLP-1 exhibited moderate affinities (IC50: 4.76 and 81.1 nM, respectively) for the human GLP-1 receptor compared with native GLP-1 (IC50: 0.37 nM). (Abu8)GLP-1 and (Val8)GLP-1 dose-dependently stimulated cAMP in insulin-secreting BRIN BD11 cells with reduced potency compared with native GLP-1 (1.5- and 3.5-fold, respectively). Consistent with other mechanisms of action, the analogues showed similar, or in the case of (Val8)GLP-1 slightly impaired insulin releasing activity in BRIN BD11 cells. Using adult obese (ob/ob) mice, (Abu8 )GLP-1 had similar glucose-lowering potency to native GLP-1 whereas the action of (Val8)GLP-1 was enhanced by 37%. The in vivo insulin-releasing activities were similar. These data indicate that substitution of Ala8 in GLP-1 with Abu or Val confers resistance to DPP IV inactivation and that (Val8)GLP-1 is a particularly potent N-terminally modified GLP-1 analogue of possible use in type 2 diabetes.

Laparoscopic greater curvature plication in morbidly obese women with type 2 diabetes:effects on glucose homeostasis, postprandial triglyceridemia and selected gut hormones

Background: Laparoscopic greater curvature plication (LGCP) is an emerging bariatric procedure that reduces the gastric volume without implantable devices or gastrectomy. The aim of this study was to explore changes in glucose homeostasis, postprandial triglyceridemia, and meal-stimulated secretion of selected gut hormones [glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), ghrelin, and obestatin] in patients with type 2 diabetes mellitus (T2DM) at 1 and 6 months after the procedure. Methods: Thirteen morbidly obese T2DM women (mean age, 53.2 ± 8.76 years; body mass index, 40.1 ± 4.59 kg/m2) were prospectively investigated before the LGCP and at 1- and 6-month follow-up. At these time points, all study patients underwent a standardized liquid mixed-meal test, and blood was sampled for assessment of plasma levels of glucose, insulin, C-peptide, triglycerides, GIP, GLP-1, ghrelin, and obestatin. Results: All patients had significant weight loss both at 1 and 6 months after the LGCP (p≤0.002), with mean percent excess weight loss (%EWL) reaching 29.7 ;plusmn2.9 % at the 6-month follow-up. Fasting hyperglycemia and hyperinsulinemia improved significantly at 6 months after the LGCP (p<0.05), with parallel improvement in insulin sensitivity and HbA1c levels (p<0.0001). Meal-induced glucose plasma levels were significantly lower at 6 months after the LGCP (p<0.0001), and postprandial triglyceridemia was also ameliorated at the 6-month follow-up (p<0.001). Postprandial GIP plasma levels were significantly increased both at 1 and 6 months after the LGCP (p<0.0001), whereas the overall meal-induced GLP-1 response was not significantly changed after the procedure (p ;gt0.05). Postprandial ghrelin plasma levels decreased at 1 and 6 months after the LGCP (p<0.0001) with no significant changes in circulating obestatin levels. Conclusion: During the initial 6-month postoperative period, LGCP induces significant weight loss and improves the metabolic profile of morbidly obese T2DM patients, while it also decreases circulating postprandial ghrelin levels and increases the meal-induced GIP response. © 2013 Springer Science+Business Media New York.

Phytoestrogen-ind uced glucose uptake and cellular proliferation in L6 myotubesadipocyte function

Aims: Oestrogens are known to act on a number of tissues throughout the body via classical oestrogen receptors, alpha (ER-a) and beta (ER-beta). Previous research has shown that oestrogens can regulate skeletal muscle glucose uptake cellular proliferation. Thus, oestrogens and related molecules provide an interesting focus for research into possible therapies for the treatment of metabolic disorders and sarcopenia. Enterodiol and enterolactone are plant derived mammalian enterolignans which share a struc- tural similarity to the human oestrogen oestradiol. Methods: In the present study we incubated the differentiated rat skeletal muscle cell line L6 concentration ranges of both com- pounds in the presence/absence of oestrogen receptor antagonists and measured glucose uptake using the non-metabolised glucose analogue 2-NBDG. Cellular proliferation was also measured using a modified MTS assay. Results: Enterolactone was seen to cause a significant increase in cellular proliferation after 48h (a maximal 25% at 0.1nmol/l), in an ER-a dependent mechanism. Incubation with 10nmol/l and 100nmol/l enterodiol caused significant increases in 2-NBDG (5000% compared with control, p < 0.001) and 2h glucose depletion from media (15% increase compared with control, p < 0.05), also in an ER-a dependent way. These results suggest these dietary derived oestrogen-like molecules might be of potential use in targeting metabolic disorders or sarcopenia. Conclusion: We can report here that the phytoestrogen derived molecules enterodiol and enterolactone interact with ER-a in the myotubes to regulate glucose uptake and cellular proliferation respectively.

The association of depression and perceived stress with beta cell function between African and Haitian Americans with and without type 2 diabetes

Background: Diabetes and diabetes-related complications are major causes of morbidity and mortality in the United States. Depressive symptoms and perceived stress have been identified as possible risk factors for beta cell dysfunction and diabetes. The purpose of this study was to assess associations between depression symptoms and perceived stress with beta cell function between African and Haitian Americans with and without type 2 diabetes. Participants and Methods: Informed consent and data were available for 462 participants (231 African Americans and 231 Haitian Americans) for this cross-sectional study. A demographic questionnaire developed by the Primary Investigator was used to collect information regarding age, gender, smoking, and ethnicity. Diabetes status was determined by self-report and confirmed by fasting blood glucose. Anthropometrics (weight, and height and waist circumference) and vital signs (blood pressure) were taken. Blood samples were drawn after 8 10 hours over-night fasting to measure lipid panel, fasting plasma glucose and serum insulin concentrations. The homeostatic model assessment, version 2 (HOMA2) computer model was used to calculate beta cell function. Depression was assessed using the Beck Depression Inventory-II (BDI-II) and stress levels were assessed using the Perceived Stress Scale (PSS). Results: Moderate to severe depressive symptoms were more likely for persons with diabetes (p = 0.030). There were no differences in perceived stress between ethnicity and diabetes status (p = 0.283). General linear models for participants with and without type 2 diabetes using beta cell function as the dependent variable showed no association with depressive symptoms and perceived stress; however, Haitian Americans had significantly lower beta cell function than African Americans both with and without diabetes and adjusting for age, gender, waist circumference and smoking. Further research is needed to compare these risk factors in other race/ethnic groups.

Acute administration of unacylated ghrelin has no effect on Basal or stimulated insulin secretion in healthy humans.

Unacylated ghrelin (UAG) is the predominant ghrelin isoform in the circulation. Despite its inability to activate the classical ghrelin receptor, preclinical studies suggest that UAG may promote β-cell function. We hypothesized that UAG would oppose the effects of acylated ghrelin (AG) on insulin secretion and glucose tolerance. AG (1 µg/kg/h), UAG (4 µg/kg/h), combined AG+UAG, or saline were infused to 17 healthy subjects (9 men and 8 women) on four occasions in randomized order. Ghrelin was infused for 30 min to achieve steady-state levels and continued through a 3-h intravenous glucose tolerance test. The acute insulin response to glucose (AIRg), insulin sensitivity index (SI), disposition index (DI), and intravenous glucose tolerance (kg) were compared for each subject during the four infusions. AG infusion raised fasting glucose levels but had no effect on fasting plasma insulin. Compared with the saline control, AG and AG+UAG both decreased AIRg, but UAG alone had no effect. SI did not differ among the treatments. AG, but not UAG, reduced DI and kg and increased plasma growth hormone. UAG did not alter growth hormone, cortisol, glucagon, or free fatty acid levels. UAG selectively decreased glucose and fructose consumption compared with the other treatments. In contrast to previous reports, acute administration of UAG does not have independent effects on glucose tolerance or β-cell function and neither augments nor antagonizes the effects of AG.

Effects of oat bran and nutrition counseling on the lipid and glucose profile and anthropometric parameters of hypercholesterolemia patients

Background: In order to prevent chronic, non communicable disease, it is essential that lifestyle is modified to include a diet high in fiber. Aim: To assess the effect oat bran (OB) in conjunction with nutrition counseling (NC) have on lipid and glucose profile, anthropometric parameters, quality of diet, and ingestion of ultraprocessed foods (UPF) and additives in hypercholesterolemia sufferers. Method: This was a 90-day, double-blind, placebo-controlled, block-randomized trial undertaken on 132 men and women with LDL-c ≥ 130 mg/dL. The participants were sorted into two groups: OB Group (OBG) and Placebo Group (PLG), and were given NC and 40g of either OB or rice flour, respectively. Lipid and glucose profile were assessed, as were the anthropometric data, quality of diet (Diet Quality Index revised for the Brazilian population - DQI-R) and whether or not UPF or additives were consumed. Results: Both groups showed a significant decrease in anthropometric parameters and blood pressure, as well as a significant reduction in total and LDL cholesterol. There was also an improvement in DQI-R in both groups and a decrease in consumption of UPF. Blood sugar, HOMA-IR and QUICKI values were found to be significantly lower only in the OBG. Conclusion: Our findings in lipid profile and anthropometric parameters signify that NC has a beneficial effect, which is attributable to the improved quality of diet and reduced consumption of UPF. Daily consumption of 40 g of OB was found to be of additional benefit, in decreasing insulin-resistance parameters.

Impaired Incretin Secretion And Pancreatic Dysfunction With Older Age And Diabetes.

To estimate the impact of aging and diabetes on insulin sensitivity, beta-cell function, adipocytokines, and incretin production. Hyperglycemic clamps, arginine tests and meal tolerance tests were performed in 50 non-obese subjects to measure insulin sensitivity (IS) and insulin secretion as well as plasma levels of glucagon, GLP-1 and GIP. Patients with diabetes and healthy control subjects were divided into the following groups: middle-aged type 2 diabetes (MA-DM), aged Type 2 diabetes (A-DM) and middle-aged or aged subjects with normal glucose tolerance (MA-NGT or A-NGT). IS, as determined by the homeostasis model assessment, glucose infusion rate, and oral glucose insulin sensitivity, was reduced in the aged and DM groups compared with MA-NGT, but it was similar in the MA-DM and A-DM groups. Insulinogenic index, first and second phase insulin secretion and the disposition indices, but not insulin response to arginine, were reduced in the aged and DM groups. Postprandial glucagon production was higher in MA-DM compared to MA-NGT. Whereas the GLP-1 production was reduced in A-DM, no differences between groups were observed in GIP production. In non-obese subjects, diabetes and aging impair insulin sensitivity. Insulin production is reduced by aging, and diabetes exacerbates this condition. Aging associated defects superimposed diabetic physiopathology, particularly regarding GLP-1 production. On the other hand, the glucose-independent secretion of insulin was preserved. Knowledge of the complex relationship between aging and diabetes could support the development of physiopathological and pharmacological based therapies.

Association Between Prehypertension, Metabolic And Inflammatory Markers, Decreased Adiponectin And Enhanced Insulinemia In Obese Subjects.

Obesity is associated with development of the cardiorenal metabolic syndrome, which is a constellation of risk factors, such as insulin resistance, inflammatory response, dyslipidemia, and high blood pressure that predispose affected individuals to well-characterized medical conditions such as diabetes, cardiovascular and kidney chronic disease. The study was designed to establish relationship between metabolic and inflammatory disorder, renal sodium retention and enhanced blood pressure in a group of obese subjects compared with age-matched, lean volunteers. The study was performed after 14 h overnight fast after and before OGTT in 13 lean (BMI 22.92 ± 2.03 kg/m(2)) and, 27 obese (BMI 36.15 ± 3.84 kg/m(2)) volunteers. Assessment of HOMA-IR and QUICKI index were calculated and circulating concentrations of TNF-α, IL-6 and C-reactive protein, measured by immunoassay. THE STUDY SHOWS THAT A HYPERINSULINEMIC (HI: 10.85 ± 4.09 μg/ml) subgroup of well-characterized metabolic syndrome bearers-obese subjects show higher glycemic and elevated blood pressure levels when compared to lean and normoinsulinemic (NI: 5.51 ± 1.18 μg/ml, P < 0.027) subjects. Here, the combination of hyperinsulinemia, higher HOMA-IR (HI: 2.19 ± 0.70 (n = 12) vs. LS: 0.83 ± 0.23 (n = 12) and NI: 0.98 ± 0.22 (n = 15), P < 0.0001) associated with lower QUICKI in HI obese when compared with LS and NI volunteers (P < 0.0001), suggests the occurrence of insulin resistance and a defect in insulin-stimulated peripheral action. Otherwise, the adiponectin measured in basal period was significantly enhanced in NI subjects when compared to HI groups (P < 0.04). The report also showed a similar insulin-mediated reduction of post-proximal urinary sodium excretion in lean (LS: 9.41 ± 0.68% vs. 6.38 ± 0.92%, P = 0.086), and normoinsulinemic (NI: 8.41 ± 0.72% vs. 5.66 ± 0.53%, P = 0.0025) and hyperinsulinemic obese subjects (HI: 8.82 ± 0.98% vs. 6.32 ± 0.67%, P = 0.0264), after oral glucose load, despite elevated insulinemic levels in hyperinsulinemic obeses. In conclusion, this study highlights the importance of adiponectin levels and dysfunctional inflammatory modulation associated with hyperinsulinemia and peripheral insulin resistance, high blood pressure, and renal dysfunction in a particular subgroup of obeses.

Effects Of High Pressure Homogenization On The Activity, Stability, Kinetics And Three-dimensional Conformation Of A Glucose Oxidase Produced By Aspergillus Niger.

High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.