Relation of protein oxidation parameters and disease activity in patients with Behçet's disease.

BACKGROUND: Behçet's disease (BD) is a chronic inflammatory vasculitis characterized by endothelial dysfunction, elevated reactive oxygen species (ROS), and neutrophil hyperfunction production including acute attacks and remission periods. Ischemia modified albumin (IMA), advanced oxidation protein products (AOPP), prooxidants-antioxidants balance (PAB), and ferric reducing antioxidant power (FRAP) were evaluated in regard to their role in the pathogenesis of BD as well as their relation to clinical presentation, uveitis attacks and remission periods, and healthy volunteers. METHODS: The study included 28 BD cases and 27 healthy volunteers as the control group. Blood samples were taken twice from each patient; first during an attack and second about three months after an attack, during remission period. RESULTS: AOPP, IMA and PAB levels were significantly increased in active periods of patients with BD compared with healthy control and remission periods of patients with BD (p < 0.0001, p < 0.0001, p < 0.0001, respectively). FRABP levels were found to be lower in active periods of patients with than healthy controls and remission periods of patients with BD (p < 0.001, p < 0.05, respectively). The AOPP levels were negatively correlated with the levels of FRAB in patients (r = -0.468, p = 0.012; r = -0.394, p = 0.038, respectively). The PAB levels were positively correlated with the levels of CRP in patients (r = -0.606, p = 0.001). CONCLUSIONS: Our results show that these parameters play a major role in the inflammatory reactions observed in BD. Increased levels of IMA and PAB are likely to be a result of inflammation-induced oxidative stress and hence its potential significance as a new marker of oxidative stress in BD.

Effects of omega-3 polyunsaturated fatty acid supplementation on serum fetuin-A levels in type 2 diabetic patients.

Fetuin-A is an endogenous inhibitor of the insulin-stimulated insulin receptor tyrosine kinase recently shown that high levels of circulating fetuin-A are associated with insulin resistance in humans suggesting that fetuin-A may represent a novel mechanism involved in the pathophysiology of type 2 diabetes (T2DM). Dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) are known to reduce triglyceride levels, but their impact on glycemic control are not well known. The aim of this study to determine the effects of omega-3 PUFA supplementation on fetuin-A and glycemic control in patients with type 2 diabetes mellitus. 40 T2DM patients (17 males/23 females; aged 39-65 years) were included in the study. Serum fetuin-A levels and metabolic and biochemical profiles were measured before (baseline) and two months after n-3 PUFA supplementations (1.2 g/day). Serum fetuin-A levels were measured by enzyme-linked immunosorbent assay. Our results indicated that serum fetuin-A, fasting glucose, HbA1c and triglyceride levels were significantly decreased after supplementation (P<0.02, P<0.001, P<0.02 and P<0.01, respectively). At baseline, serum fetuin-A levels were correlated with HbA1c (r:-0.391, P<0.04). A significant positive correlation between fetuin-A and both triglycerides (r: 0.343, P<0.05) and total cholesterol (r: 0.330, P<0.05) and negative correlation between fetuin-A and fasting glucose (r: -0.405, P<0.01) were found after the supplementations. When performed multiply regression analysis, we found that serum fetuin-a levels were related with triglyceride levels (r: 0.351, P<0.01) at baseline and HbA1c levels (r: 0.344, P<0.04) after the supplementation. Based on the results, it thought that omega-3 PUFA intake decreases serum fetuin-A levels and serum fetuin-A is associated with plasma lipids and glycemic controls in type 2 diabetic patients. Further studies are required to resolve the question.

The relationship between ischemia modified albumin and oxidative stress parameters in patients with cardiac syndrome X.

BACKGROUND: The objective of this study was to evaluate the serum levels of ischemia modified albumin and oxidative stress parameters in patients with cardiac syndrome X. METHODS: A total of 61 patients, composed of 32 consecutive patients (24 female, 8 male, average age: 47.63 +/- 9.49 years) diagnosed with cardiac syndrome X by coronary angiography (initially performed following the identification of ischemia by exercise stress test or myocardial perfusion scintigraphy) and a control group of 29 consecutive patients (15 female, 14 male, average age: 49.59 +/- 11.68 years) with similar features without cardiac syndrome X were included in the study. The levels of the ischemia modified albumin (IMA), ferric reducing antioxidant power (FRAP), prooxidant-antioxidant balance (PAB), and advanced protein oxidation products (AOPP) were determined by colorimetric methods. RESULTS: Patients have significantly higher PAB, AOPP, and IMA levels in the patient group than in the control group (p < 0.01, p < 0.001, and p < 0.02, respectively). Also, serum triglyceride (p < 0.005) and hs-CRP (p < 0.0001) levels were significantly higher in the patient group (p < 0.01, p < 0.001, and p < 0.02, respectively). We found that there was a significant correlation between hs-CRP, plasma PAB (r: 0.258; p < 0.05), AOPP (r: 0.459; p < 0.001), and triglyceride levels (r: 0.404; p < 0.01). Plasma AOPP levels were also significantly positive correlated with triglyceride levels (r: 0.463; p < 0.001). In addition, during the correlation analysis performed on the patient group, a positive correlation was observed between the levels of IMA with the levels of plasma PAB and plasma AOPP (r: 0,994; p < 0.01 and r: 0.857; p < 0.05, respectively) In a multiple linear regression analysis, AOPP levels were significantly related with hs-CRP and triglyceride (R2: 0.380, p < 0.0001 and p < 0.05). Simple linear regression analysis was performed between plasma PAB (as dependent variable) and hs-CRP levels. Plasma PAB levels were related with hs-CRP (R2: 0.258, p < 0.05). Using the receiver-operator characteristic (ROC) curve, the best cut-off values for predicting cardiac syndrome X of PAD, AOPP, IMA, and hs-CRP levels were 88.1 arbitrary units, 68.5 kloramin T micromol/L, 7.17 U/mL, and 1.09 mg/dL, respectively. CONCLUSIONS: Based on the results of our study, the increase in oxidative stress during cardiac syndrome X appears to be related to elevated levels of IMA. Treatment modalities that decrease oxidative stress might be beneficial for the treatment of cardiac syndrome X.

The effect of agmatine on the vascular reactivity in streptozotocin-diabetic rats.

AIM: We investigated the vascular effects of agmatine (decarboxylated arginine=AGM), an endogenous ligand for alpha(2)-adrenoceptors and imidazoline receptors, present in endothelium and smooth muscle, using the diabetic rat aortae. MATERIALS AND METHODS: Studies were performed in control group (0.2 ml i.p. saline, n=10), streptozotocin (STZ)-diabetic control group (60 mg kg(-1) STZ i.p., n=10), agmatine (AGM)-control group (5 mg kg(-1)day(-1) i.p. AGM for 1 month, n=10), citrate-control group (0.2 ml 0.01 M, n=10), insulin-treated diabetic group ((3 U kg(-1) NPH+1 U kg(-1) regular insulin) twice per day, for 1 month, n=10) and AGM-treated diabetic group (5 mg kg(-1)day(-1) i.p. for 1 month, n=10). All values are expressed as means+/-S.E.M. Statistical analysis of the data was performed using ANOVA followed by Tukey multiple comparisons test. RESULTS: One-month AGM-treatment significantly decreased the blood glucose levels of diabetic rats (502+/-44 mg dl(-1) to 343+/-31 mg dl(-1), P<0.001). Fast, slow and total components of responses to noradrenaline in all the experimental groups were not significantly affected by AGM-treatment. AGM reversed the decreased responses of acetylcholine (pD(2) and Inh.%, P<0.001 and P<0.05) in diabetic rats although it did not affect the responses of sodium nitroprusside in all groups. The contraction values of KCl in all groups were not affected by AGM-treatment. CONCLUSION: AGM-treatment could improve the increased blood glucose level, reverse the endothelial dysfunction and normalize the endothelium-dependent relaxation responses in STZ-diabetic rats.

Effect of 5-aminoimidazole-4-carboxamide riboside (AICA-r) on isolated thoracic aorta responses in streptozotocin-diabetic rats.

Diabetes mellitus alters the vascular responsiveness to several vasoconstrictors and vasodilators. 5-amino-4-imidazole-carboxamide riboside (AICA-r), a nucleoside corresponding to AICA-ribotide and an intermediate of the de novo pathway of purine biosynthesis, was recently proposed as a new insulinotropic tool in non-insulin-dependent diabetes mellitus. The aim of the present study was to define whether AICA-r affects altered vascular responsiveness to vasoconstrictors and vasodilators in the thoracic aorta of neonatal streptozotocin (STZ)-diabetic rats. The results of this study indicate that a 1-month treatment with AICA-r significantly increases the body weight in diabetic rats; significantly decreases the blood glucose level of diabetic rats (from 302+/-47 to 135+/-11 mg/dL, p<0.001); does not significantly affect the fast, slow, and total components of responses to noradrenaline in all the experimental groups; reverses the increased Emax values of noradrenaline in diabetic rats to near-control values; reverses the completely abolished responses of acetylcholine (pD2 and percent relaxation) in diabetic rats to control values; and reverses the decreased pD2 values of sodium nitroprussiate in diabetic rats to control values. In conclusion, AICA-r treatment in neonatal STZ-diabetic rats improved increased blood glucose levels, accelerated weight gain, reversed endothelial dysfunction, and normalized vascular responses.

Effect of hyperoxia and metformin on vascular responses to vasoactive compounds in rats.

Exposure of cells to oxygen concentrations higher than normal (hyperoxia) damages the molecular components of cells, resulting in cellular dysfunction and death. Metformin, a biguanide molecule used for treating non-insulin-dependent diabetes, been shown to lower blood pressure. The aim of this study was to investigate the possible effects of hyperoxia and metformin on the vascular responses of thoracic aorta to vasoactive compounds, using an in vitro rat model. In the hyperoxia-control (HC) group, the response to acetylcholine was completely abolished, but metformin treatment before (MH) or after (HM) exposure to 100% oxygen restored the response to acetylcholine to near-control values. In aortas from HC, MH, or HM groups, no significant differences were found in pD2 values to the endothelium-dependent vasodilator sodium nitroprussiate. In aortic strips from metformin-treated rats, the pD2 values for noradrenaline in the presence of endothelium were significantly smaller than those in the normal control group. The maximal contractile responses to KCl were not significantly different among all experimental groups. The results of the present study show that in hyperoxia-exposed rats, metformin treatment reverses the abolished vascular relaxation to AChe.

Impaired relaxation in aorta from streptozotocin-diabetic rats: effect of aminoguanidine (AMNG) treatment.

AIM: The effect of 8 weeks' streptozotocin (STZ)-induced diabetes and aminoguanidine (AMNG), the inhibitor of advanced glycosylation reaction, treatment on arteriolar reactivity to vasoactive substances was investigated in vitro. MATERIALS AND METHODS: Studies were performed in untreated control rats (n=10), STZ-induced (60 mg/kg i.v.) diabetic rats (n=10), AMNG-treated (600mg/l given in drinking water throughout 8 weeks) control rats (n=10) and AMNG-treated (600mg/l given in drinking water, beginning at 72h after STZ and throughout 8 weeks of diabetes) diabetic rats (n=10). Results are expressed as the mean +/-s.e. Relaxant responses are expressed as a percentage (%) relaxation of noradrenaline-induced tone. Statistical comparisons were made by one-way analysis of variance (ANOVA) followed by Tukey-Kramer multiple comparisons test. RESULTS: 1. The decreased body weights (205 +/- 6g) and increased blood glucose levels (583 +/- 8 mg/dl) of diabetic rats were partially restored by treatment of aminoguanidine (253 +/- 6 g, p < 0.05 and 480 +/- 14 mg/ dl, p < 0.001, respectively). 2. Diabetes caused a 71% deficit in maximal endothelium-dependent relaxation to acetylcholine for noradrenaline precontracted aortas (p<0.001). AMNG treatment prevented the diabetes-induced impairment in endothelium dependent relaxation (58 +/- 8%) to acetylcholine, maximum relaxation remaining in the non-diabetic range (78 +/- 4%). 3. Neither diabetes nor treatment affected endothelium-independent relaxation (pD2 and max. Relax.) to sodium nitroprusside. 4. Vasoconstrictor responses (pD2 and Max. Contraction) to noradrenaline and KCl were not influenced by the diabetic state and treatment. CONCLUSION: Our data suggest that 8 weeks of experimental diabetes is associated with a decreased endothelium-dependent vasodilatation. AMNG treatment may prevent diabetes-induced endothelial dysfunction. This may be mediated via the prevention of advanced glycosylation end product formation, the enhanced release of vasodilator substances such as prostacyclin, the increased elasticity of blood vessels, the antioxidant activity and inhibitor activity of enzyme aldose-reductase by AMNG.

The effect of tizanidine on maximal electroshock seizures (MES) in mice.

Tizanidine, an alpha-2 adrenergic agonist, is a centrally active muscle relaxant and a spasmolytic drug. The aim of our study was to investigate the activity of tizanidine on maximal electroshock seizures (MES) in mice. In the first part of the study, convulsive current 50 (CC 50) value to produce seizures was found. Then, tizanidine was given intraperitoneally (IP) at the doses of 0.5, 1, and 2 mg/kg, and orally (PO) at the doses of 5, 10, 20, 40 mg/kg. We found that tizanidine at the doses of 1 and 2 mg/kg IP and 40 mg/kg PO caused a significant protection against MES. In the second part of the study, after pretreatment with yohimbine, an alpha-2 adrenergic receptor blocker, at the dose of 2 mg/kg, anticonvulsant effect of tizanidine is diminished. We concluded that the mode of action of the anticonvulsant effect of tizanidine may be mediated by the central alpha-2 adrenergic receptors.

The effect of succinic acid monomethyl ester (SAM) on the responses of isolated thoracic aorta in streptozotocin-diabetic rats.

Succinic acid monomethyl ester (SAM) was recently proposed as an insulinotropic tool in non-insulin-dependent diabetes mellitus. The present study was designed to define whether SAM has the vascular effect in thoracic aorta of streptozotocin (STZ)-diabetic rats. (1) Body weights of diabetic rats were significantly increased after SAM treatment (P < 0.05). (2) Ten-day SAM treatment did not significantly affect blood glucose levels in SAM-treated control and SAM-treated STZ-diabetic rats. (3) Maximum tension responses to noradrenaline and KCl (80 mmol l-1) were not significantly different among all the experimental groups. (4) pD2 (-log EC50) values for noradrenaline of untreated diabetic rats were significantly less than those of controls, SAM-treated control and SAM-treated diabetic rats (P < 0.01, P < 0.001 and P < 0.05, respectively). SAM treatment normalized the decreased sensitivity of noradrenaline response in diabetic rats. (5) Fast, slow and total components of responses to noradrenaline (10(-5) mol l-1 approximately equal to EC90) were not significantly different among all the experimental groups. (6) There were no significant differences between aorta precontracted with noradrenaline from controls and STZ-diabetic (untreated and SAM-treated) rats in pD2 values and the potency of maximum relaxation to acetylcholine or in pD2 values to sodium nitroprusside. In conclusion, 10-day SAM treatment increases the sensitivity of diabetic-aortic rings to noradrenaline compared to untreated diabetic control rats.

The effect of isradipine on maximal electroshock seizures in mice.

1. The aim of this study was to investigate the possible anticonvulsant effect of a dihydropyridine calcium antagonist, isradipine, which easily crosses the blood-brain barrier displaying high affinity and specificity for the brain L-type voltage-sensitive calcium channel, on maximal electroshock seizures in mice. 2. Isradipine at i.p. doses of 2.5 mg/kg and 5.0 mg/kg was found to cause a statistically significant increase in the convulsion threshold of maximal electroshock seizures in a dose-dependent manner (P = 0.047 and P = 0.022, respectively). 3. It was concluded that the mode of action of the anticonvulsant effect of isradipine is related to blockade of the intraneuronal calcium currents, which play an important role in epileptic activity.

Penetration of topically applied ciprofloxacin, norfloxacin and ofloxacin into the aqueous humor of the uninflamed human eye.

This study was undertaken to compare aqueous humor penetration of topical 0.3% ciprofloxacin, 0.3% norfloxacin and 0.3% ofloxacin in 63 patients undergoing cataract surgery. The patients were divided into two groups. Group 1 (long-term treatment) involved 30 patients undergoing cataract extraction who received either 0.3% ciprofloxacin, 0.3% norfloxacin or 0.3% ofloxacin topical drops. Each patient was preoperatively given a single drop per hour six times. At the time of surgery, 0.1 ml aqueous fluid was aspirated from the anterior chamber and immediately stored at -70 degrees C. Topically applied ciprofloxacin, ofloxacin and norfloxacin achieved mean aqueous humor levels of 2.80 +/- 1.07, 2.95 +/- 1.19 and 1.50 +/- 0.48 micrograms/ml respectively. There was no statistically significant difference in intraocular mean aqueous levels of ciprofloxacin versus ofloxacin. Topical ciprofloxacin and ofloxacin achieved mean aqueous humor levels significantly higher than norfloxacin (p < 0.001 and p < 0.0008 respectively). Group 2 (short-term treatment) involved 33 patients undergoing cataract extraction who received 0.3% ciprofloxacin, 0.3% ofloxacin and 0.3% norfloxacin topical drops. These patients were given one drop at 90 minutes and one drop 30 minutes preoperatively. At the time of surgery, 0.1 ml aqueous fluid was aspirated from the anterior chamber and immediately stored at -70 degrees C. Topically applied ciprofloxacin, ofloxacin and norfloxacin achieved mean aqueous humor levels of 1.11 +/- 0.50, 1.50 +/- 0.62 and 1.20 +/- 0.43 micrograms/ml respectively. There was no statistically significant difference in intraocular mean aqueous humor levels of ofloxacin versus norfloxacin and ciprofloxacin versus norfloxacin. Topical ofloxacin achieved a significantly higher mean aqueous humor level than ciprofloxacin (p < 0.03). All levels were above the minimum inhibitory concentrations of ciprofloxacin, ofloxacin and norfloxacin for most of the sensitive organisms.

Comparative tear concentrations of topically applied ciprofloxacin, ofloxacin, and norfloxacin in human eyes.

The tear pharmacokinetic profiles of 0.3% ciprofloxacin, 0.3% ofloxacin, and 0.3% norfloxacin ophthalmic solutions after a single drop topically administrations in the eyes of 30 healthy volunteers were evaluated. Tear samples collected at 30, 120, 180, and 240 minutes, were analyzed for drug concentrations by high performance liquid chromatography (HPLC) with fluorometric detection. Topically applied ciprofloxacin, ofloxacin, and norfloxacin achieved the mean tear concentrations (mean +/- SD) of 11.28 +/- 6.98, 6.52 +/- 4.06, and 13.28 +/- 8.78 micrograms/g at 30 min, and then fell to 3.52 +/- 1.30, 4.82 +/- 1.80, and 5.79 +/- 4.80 micrograms/g at 240 min, respectively. Topical norfloxacin achieved mean tear level significantly higher than ofloxacin at 30 min (p = 0.031). There were no statistically significant differences in the mean tear levels of ciprofloxacin versus ofloxacin (at 30, 120, 180, and 240 min), ciprofloxacin versus norfloxacin (at 30, 120, 180, and 240 min) and ofloxacin versus norfloxacin (at 120, 180, and 240 min). However, the mean tear levels, 240 min after dosing ciprofloxacin and norfloxacin, fell to the statistically significant concentrations (p = 0.02 and p = 0.01, respectively). But, it is concluded that concentrations of ciprofloxacin, ofloxacin, and norfloxacin in tears were still significantly greater than the minimum inhibitory concentrations for the most sensitive organisms, 240 min after a single drop application.

Quantification of ofloxacin in biological fluids by high-performance liquid chromatography.

A simple HPLC assay was evaluated for analysis of ofloxacin in biological fluids. Mobile phase contained methanol (40%) and phosphate buffer (pH 3.5, 60 mmol/l) and a common C18 column was used. Detection was set at 280 nm (UV). Biological fluids (50 microliters) were prepared for assay by protein precipitation with acetonitrile (1/1, vol/vol). The assay is linear from 2000 to 10 ng/ml and sensitive to 10 ng/ml. The mean recovery of ofloxacin from serum was 99.4%. The coefficient of variation was < or = 4.0% for same-day precision and < or = 6.8% for assay-to-assay precision. Because the assay requires only small specimens volumes and minimal sample preparation, this assay provides a simple to use, sensitive and specific method for quantification of ofloxacin in biological fluids.