Asprosin, visfatin and subfatin as new biomarkers of obesity and metabolic syndrome

OBJECTIVE

Metabolic syndrome (MetS) and obesity are important public health problems associated with adipose tissue mass. Asprosin, visfatin, and subfatin are new members of which fate in MetS and obesity has not been fully revealed yet. Thus, this study was to investigate the association between asprosin, visfatin, subfatin, and biochemical values, demographic data, and body composition measurement values in MetS patients with and without obesity.

PATIENTS AND METHODS

Blood samples were taken from a total of 90 people, including 31 MetS patients with obesity, 29 MetS patients without obesity, and 30 healthy (control). Asprosin, visfatin, and subfatin were studied by the ELISA method.

RESULTS

There was a negative correlation between asprosin and Body Mass Index (BMI) in the MetS + Obese group. The correlations between asprosin and urea and fasting insulin (FI) levels in the MetS group were positive and statistically significant (p < 0.05). While there was a statistically significant negative correlation (p < 0.05) between visfatin and BMI in the MetS + Obese group, the correlation with waist circumference in the MetS + Obese and MetS groups was statistically significant and negative (p < 0.05). There was a statistically significant negative relationship (p < 0.05) between aspartate aminotransferase value and visfatin. The results between visfatin values and asprosin and subfatin in all groups were significant (p < 0.05).

CONCLUSIONS

There is a direct relationship between circulating amounts of asprosin, visfatin, and subfatin hormones and age, weight, height, diastolic blood pressure, high-density lipoprotein-cholesterol, aspartate aminotransferase, alanine transaminase, and creatinine. Therefore, asprosin, visfatin, and subfatin hormones are the new biomarkers of metabolic turbulence.

First synthesis of silicon nanocrystals in amorphous silicon nitride from a preceramic polymer

We report the first synthesis of silicon nanocrystals embedded in a silicon nitride matrix through a direct pyrolysis of a preceramic polymer (perhydropolysilazane). Structural analysis carried out by XRD, XPS, Raman and TEM reveals the formation of silicon quantum dots and correlates the microstructures with the annealing temperature. The photoluminescence of the nanocomposites was investigated by both linear and nonlinear measurements. Furthermore we demonstrate an enhanced chemical resistance of the nitride matrix, compared to the typical oxide one, in both strongly acidic and basic environments. The proposed synthesis via polymer pyrolysis is a striking innovation potentially allowing a mass-scale production nitride embedded Si nanocrystals.

Nitric oxide and asymmetric dimethylarginine and CD 40 ligand levels in malignancy associated thrombosis and their modulation by anticoagulants

17049

Background: Cancer associated thrombotic complications are primarily due to endothelial dysfunction and upregulation of inflammatory processes. Nitric oxide (NO) represents one of the major endothelial derived vasoactive mediators. Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NO synthase which inhibits NO production at pathophysiologic levels. CD 40 ligand (CD 40L) is also upregulated in cancer. Methods: To test the hypothesis that endothelial dysfunction in cancer patients may result in increased ADMA levels, plasma samples were retrospectively analyzed from an open label, multidose, active comparator designed study in which all patients (n=110) were initially treated with low molecular weight heparin, enoxaparin (E) at 1–1.5 mg/kg sc for 5 days and further subdivided into group E which continued to receive E and warfarin (W) group which was given oral anticoagulants for a period of up to 12 weeks. Baseline blood samples (BL), 5 days post E (IPE) and 4–6 week samples from the E and W were analyzed for ADMA and CD 40L levels by ELISA methods. NO levels were measured using a chromogenic method. Results: The baseline levels of NO, ADMA and CD 40L levels were markedly elevated in cancer patients. The E treated group showed a marked decrease in the ADMA and CD 40L levels which persisted throughout the treatment period. However, in the W converted group the ADMA and CD 40L levels rebounded to an increased level indicating that E differentially regulated ADMA in these patients. The down regulation pattern of NO was similar for both E and W. Conclusions: These results suggest that patients with cancer and thrombosis exhibit simultaneous upregulation of ADMA, CD 40L and NO. While E and W show a differential regulation of ADMA and CD 40L, both result in a downregulation of NO. The fact that E regulates ADMA is highly suggestive of its role in iNOS regulation which may be involved in the inflammatory response in cancer patients.

[Table: see text]

No significant financial relationships to disclose.

The antithrombotic efficacy of the GP IIb/IIIa antagonist SR121787 is potentiated by antithrombin-dependent factor Xa inhibition without an increase in the bleeding risk in the rabbit

Current antithrombotic therapy in acute coronary symptoms is only partially effective and exhibits bleeding complications. These experiments were designed to address the antithrombotic and hemorrhagic interactions of the novel glycoprotein (GP) IIb/IIIa antagonist SR121787 in combination with the indirect inhibitor of factor Xa, SR90107/ORG31540. Thrombogenesis was initiated by electrolytic injury of the intimal surface of the carotid artery, and thrombus formation was assessed by recording carotid blood flow and by measuring thrombus weight 45 min after electrical stimulation. SR121787 was an efficacious antithrombotic agent in this model (ED50 = 16.3+/-0.3 mg/kg, p.o.), whereas heparin (4.5 mg/kg, i.v.) and SR90107/ORG31540 [1 mg/kg (850 aXa anti-units/kg), i.v.] were only marginally effective (17 and 27% inhibition of carotid blood flow reduction, respectively). Coadministrations of heparin (4.5 mg/kg, i.v.) or SR90107/ORG31540 (0.5 mg/kg, i.v.) were found to potentiate the antithrombotic efficacy of threshold doses of SR121787 (5 or 10 mg/kg, p.o.). The enhancement of the antithrombotic efficacy of SR121787 by SR90107/ORG31540 was--contrary to the association of SR121787 with heparin--not accompanied by an increased blood loss from the incised rabbit ear. Coadministrations of heparin or SR90107/ORG31540 did not influence the ex vivo antiaggregatory activity of SR121787. SR121787 coadministration did not alter the systemic anticoagulant activities in heparin or SR90107/ORG31540-treated animals. These data suggest the potential for optimized antithrombotic treatment in acute coronary syndromes when a GP IIb/IIIa antagonist (SR121787) is combined with an antithrombin-dependent factor Xa inhibitor (SR90107/ORG31540).

Hypoxia primes endotoxin-induced tissue factor expression in human monocytes and endothelial cells by a PAF-dependent mechanism

Tissue factor (TF) is a glycoprotein which acts as a trigger of the coagulation cascade. TF expression may be induced at the surface of monocytes and endothelial cells by several stimuli including bacterial endotoxin (LPS) and cytokines (IL 1 beta, TNF alpha) and there is a large body of evidence for the involvement of hypoxia as a primaring factor in the process leading to thrombosis. To define the molecular basis underlying this phenomenon, we evaluated the relative role of platelet activating factor (PAF). PAF primed human monocytes and human umbilical vein endothelial cells (HUVEC) for TF expression following exposure to E coli LPS but was unable to enhance the induction of TF expression by IL 1 beta. The priming effect of PAF with regard to LPS occurred in a time- and dose-dependent manner and was inhibited by the PAF receptor antagonist SR 27417. When HUVEC or monocytes were exposed to an hypoxic environment, a significant rise in LPS-induced TF expression was observed. Hypoxia had no effect on IL 1-induced TF expression. The enhanced LPS-induced TF expression in both cell types was mediated by PAF as indicated by the inhibition obtained with SR 27417, added during hypoxia. Although the importance of hypoxia in the etiology of venous thrombosis has been acknowledged for a long time, evaluation of the relative importance of PAF in the process leading to thrombus formation is still lacking. Stasis-induced thrombosis performed in the rabbit jugular vein was enhanced in a dose-dependent manner by the prior i.v. administration of LPS (0.05 to 100 micrograms/ kg, i.v.). SR 27417 administered simultaneously with LPS prevented thrombus formation with an ED50 value of 0.1 +/- 0.04 mg/kg. These results therefore show that hypoxia promotes LPS-induced TF expression in HUVEC and human monocytes through a PAF-dependent mechanism in vitro and in vivo.

Ability of different flavonoids to inhibit the procoagulant activity of adherent human monocytes

Sixty-five natural flavonoids of various chemical classes were screened for their ability to inhibit the procoagulant activity of adherent human monocytes stimulated by endotoxin and interleukin-1 beta in vitro. Eighteen of these compounds inhibited the interleukin-1 beta-induced expression of tissue factor on human monocytes, but the most active compound was a biflavonoid: hinokiflavone.

Aurin tricarboxylic acid inhibits experimental venous thrombosis

In vitro, aurin tricarboxylic acid (ATA) inhibited ristocetin-induced human platelet agglutination in a dose-dependent manner. The IC50 value (dose which inhibits 50% of platelet agglutination) was 60 +/- 8.7 micrograms/ml. In vivo, the i.v. administration of ATA to rats reduced the thrombus formation in an arteriovenous shunt with an ED50 value of 9.0 +/- 1.6 mg/kg. In a venous thrombosis model, using a combination of a thrombogenic challenge and stasis, ATA displayed a significant, dose-dependent antithrombotic effect, the ED50 value being of 18.3 +/- 2.0 mg/kg. In an experimental model of disseminated intravascular coagulation, ATA protected mice from the lethal effect of thromboplastin-induced thromboembolism with a ED50 value of 1.1 +/- 0.15 mg/kg, being in that respect 12 times less potent than standard heparin (ED50 = 90 +/- 15 micrograms/kg). These observations therefore show that ATA is active in both arterial- or venous-type thrombosis models and suggest that von Willebrand Factor might be important not only in arterial but also in venous thrombosis.

Biochemical and pharmacological properties of SR 27388, a dual antioxidant and PAF receptor antagonist

SR 27388 (N-(2-dimethylaminoethyl)-N-(3-pyridinylmethyl[4-(3,5-di(tert- butyl)-4-hydroxylphenyl)thiazol-2-yl]amine) is a potent and competitive antagonist of the binding of [3H]PAF to its receptor on rabbit platelets exhibiting an equilibrium inhibition constant for PAF binding of 10.5 +/- 1.2 nM (n = 3). SR 27388 potently inhibited PAF-induced aggregation of rabbit platelets in vitro (IC50 = 65 +/- 12 nM) (n = 4). In this respect, SR 27388 was as potent as the triazolothienodiazepine WEB-2086 against PAF-induced aggregation of rabbit platelets and had no effect on the action of other platelet aggregating agents. SR 27388 prevented in a dose-dependent manner the formation of thiobarbituric acid reactive substances during membrane peroxidation (IC50 = 0.7 microM) and inhibited reduction of the stable 1,1-diphenyl-2-picrylhydrazyl radical, indicating that the antioxidant potency of SR 27388 was due to an efficient radical scavenging activity. SR 27388 displayed marked in vitro inhibition of zymosan-induced oxidative burst in human monuclear cells (IC50 = 3 microM). In vivo, SR 27388 protected mice from 100 micrograms/kg PAF-induced death with an ED50 value of 500 micrograms/kg, when given i.v., 5 min before PAF challenge or p.o. (ED50 = 800 micrograms/kg) when given 1 h before PAF administration. Similarly, i.v. or oral doses of SR 27388 afforded in mice complete protection against endotoxin-induced lethality (ED50 values were 250 micrograms/kg and 1.3 mg/kg, respectively). Neither BHT, vitamin E nor catechin exhibited significant protection against PAF- or endotoxin-induced death. In ovalbumin-presensitized rabbits, SR 27388 premixed with the allergen inhibited in a dose-dependent manner allergen-induced oedema formation in the skin (ED50 = 0.1 mumol/site). After an i.v. administration of 10 mg/kg, SR 27388 significantly protected mice against alloxan-induced diabetes. These results show that SR 27388 is a potent and orally active dual PAF receptor antagonist and antioxidant.

IL-4 inhibits LPS-, IL-1 beta- and TNF alpha-induced expression of tissue factor in endothelial cells and monocytes

Inflammatory mediators such as endotoxin, interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) dose-dependently increased the expression of tissue factor on the surface of cultured bovine aortic endothelial cells (ABAE), human umbilical vein endothelial cells (HUVEC) and human monocytes. In ABAE, endotoxin-, IL-1 beta- and TNF alpha-induced tissue factor expression was suppressed by interleukin-4 (IL-4) which also neutralized the pyrogenic effect of endotoxin in HUVEC and monocytes. IL-4 did not alter TNF-alpha-induced procoagulant changes in HUVEC and monocytes but strongly protected the monocyte surface against IL-1 beta-induced procoagulant changes.

Biochemical and pharmacological activities of SR 27417, a highly potent, long-acting platelet-activating factor receptor antagonist

SR 27417 [N-(2-dimethylamino ethyl)-N-(3-pyridinyl methyl)[4- (2,4,6-triisopropylphenyl) thiazol-2-yl]amine] is the first member of a newly developed platelet-activating factor (PAF) antagonist series. It is a highly potent, competitive and selective antagonist of the binding of [3H]PAF to its receptor in rabbit platelets. It exhibits an equilibrium inhibition constant for PAF binding of 57 pM, a value that is at least 5-fold lower than that of unlabeled PAF itself. SR 27417 potently inhibited PAF-induced aggregation of rabbit and human platelets in vitro (IC50 = 0.10 and 0.50 nM, respectively) but had no effect on the action of other platelet-aggregating agents. In comparison with the triazolothienodiazepine WEB-2086, SR 27417 was 470 and 70 times more potent against PAF-induced aggregation of rabbit and human platelets, respectively. SR 27417 displayed marked in vitro inhibition of PAF-induced oxidative burst in guinea pig macrophages (IC50 = 32 nM). In an in vivo model, it protected mice from 100 micrograms/kg PAF-induced death when given i.v. (ED50 = 7.5 micrograms/kg) 5 min before PAF challenge or p.o. (ED50 = 45 micrograms/kg) 3 hr before PAF administration. SR 27417 inhibited PAF-induced death in mice with an impressive p.o. or i.v. duration of action of 30 to 48 hr. In anesthetized guinea pigs, SR 27417 inhibited i.v. and p.o. 100 ng/kg PAF-induced bronchoconstriction (ED50 = 14 and 140 micrograms/kg, respectively), hemoconcentration (ED50 = 20 and 270 micrograms/kg, respectively), thrombocytopenia (ED50 = 30 and 240 micrograms/kg, respectively) and leukopenia (ED50 = 0.1 and 1.5 mg/kg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)