l-Arginine attenuates lymphocyte activation and anti-oxidized LDL antibody levels in patients undergoing angioplasty

A novel conductometric biosensor based on hybrid organic/inorganic recognition element for determination of L-arginine

A highly accurate conductometric biosensor for determination of L-arginine (L-arg) in the real samples with the complex sample matrices was developed by co-immobilization of arginase, urease and the ammonium-sensitive zeolite clinoptilolite (Clt). The biosensors with different mutual arrangements of the enzyme component and zeolite on the sensitive surface of the gold interdigitated electrodes were studied and compared. The studies showed that the biosensor containing the primary layer of Clt deposited on the electrode surface followed by arginase and urease co-immobilized as the secondary layer has the most advantageous analytical characteristics compared to the biosensors based on other configurations of the bioselective membrane. In particular, for this biosensor they were as follows: sensitivity 9.61 ± 0.01 μS/mM, limit of detection 5 μM, linear range 0-280 μM and dynamic range 0-15 mM. The biosensor demonstrated high operational stability and storage stability. The effect of solution parameters (pH, ionic strength and buffer capacity) on the biosensor sensitivity was studied. Finally, we used the developed biosensor for quantification of L-arg in the food samples. The results of the biosensor analysis were compared with the control method (ion chromatography). The data of the biosensor method demonstrated high correlation with the reference data (R = 0.96).

Adaptation of Conductometric Monoenzyme Biosensor for Rapid Quantitative Analysis of L-arginine in Dietary Supplements

The present study reports on the development, adaptation, and optimization of a novel monoenzyme conductometric biosensor based on a recombinant arginine deiminase (ADI) for the determination of arginine in dietary supplements with a high accuracy of results. Aiming for the highly sensitive determination of arginine in real samples, we studied the effect of parameters of the working buffer solution (its pH, buffer capacity, ionic strength, temperature, and protein concentration) on the sensitivity of the biosensor to arginine. Thus, it was determined that the optimal buffer is a 5 mM phosphate buffer solution with pH 6.2, and the optimal temperature is 39.5 °C. The linear functioning range is 2.5-750 µM of L-arginine with a minimal limit of detection of 2 µM. The concentration of arginine in food additive samples was determined using the developed ADI-based biosensor. Based on the obtained results, the most effective method of biosensor analysis using the method of standard additions was chosen. It was also checked how the reproducibility of the biosensor changes during the analysis of pharmaceutical samples. The results of the determination of arginine in real samples using a conductometric biosensor based on ADI clearly correlated with the data obtained using the method of ion-exchange chromatography and enzymatic spectrophotometric analysis. We concluded that the developed biosensor would be effective for the accurate and selective determination of arginine in dietary supplements intended for the prevention and/or elimination of arginine deficiency.

Effect of intensive atorvastatin therapy on periprocedural PDCD4 expression in CD4+ T lymphocytes of patients with unstable angina undergoing percutaneous coronary intervention

OBJECTIVE

To investigate the effects of intensive atorvastatin therapy on programmed cell death 4 (PDCD4) expression by CD4+ T lymphocytes in patients with unstable angina who received percutaneous coronary intervention (PCI).

METHODS

Patients with unstable angina were randomized to pretreatment with either an intensive dose (80 mg/day, n = 33) or a conventional dose (20 mg/day, n = 33) of atorvastatin. Circulating CD4+ T cells were subsequently obtained prior to PCI, and also 18-24 h after PCI, using a magnetic cell sorting system. Fluorescence-based quantitative real-time PCR was then used to measure levels of PDCD4 mRNA in the isolated CD4+ T lymphocytes, and Western blot analysis was used to detect levels of PDCD4. Serum levels of interleukin (IL)-10 and TNF-α were quantified using enzyme-linked immunosorbent assays.

RESULTS

Of the 66 patients with unstable angina that were examined, levels of PDCD4 mRNA and protein were found to dramatically decrease in patients who received an intensive dose of atorvastatin following PCI (p < 0.05). In contrast, serum levels of TNF-α significantly increased following PCI in both the intensive dose group and the conventional dose group, with the latter being higher than the former (p < 0.05). Serum IL-10 levels also markedly increased following PCI for the two groups. However, higher values were associated with the intensive dose group (p < 0.05).

CONCLUSIONS

Intensive atorvastatin treatment reduced the post-PCI myocardial inflammatory response in patients with unstable angina, possibly by inhibiting PDCD4 expression in CD4+ T lymphocytes.

Lipid Metabolism in Rats is Modified by Nitric Oxide Availability Through a Ca++-Dependent Mechanism

We studied lipid metabolism and the antioxidant defense system in plasma and liver of rats fed diets supplemented with L(omega)-nitro-L-arginine methyl ester (L-NAME), isosorbide dinitrate (DIS), L-arginine (Arg), or the associations of these drugs. Liver hydroperoxide and thiobarbituric-acid-reactive substance (TBARS) levels were decreased by Arg and increased by L-NAME or DIS treatments. Oxidized glutathione and conjugated dienes were increased by DIS. Nitrate + nitrite levels and serum calcium ([Ca(++)]) were incremented by Arg or DIS and reduced by L-NAME. Superoxide dismutase and catalase activities decreased under Arg treatment, while L-NAME or DIS caused stimulation. Liver high-density lipoprotein (HDL) cholesterol was increased by DIS or NAME (alone or associated with Arg). Free fatty acids and neutral and polar lipids were increased by Arg, L: -NAME, and DIS. However, predominating phospholipid synthesis increased the neutral/polar ratio. Decreased levels of nitric oxide (NO) (low [Ca(++)]) was directly associated with increased fatty acid synthetase, decreased phospholipase A(2), carnitine-palmitoyl transferase, and fatty acid desaturase activities. Raised NO (high [Ca(++)]) inversely correlated with increased phospholipase-A(2) and acyl-coenzyme A (CoA) synthetase and decreased fatty acid synthetase and beta-oxidation rate. Arg or DIS produced changes that were partially reverted by association with L-NAME. Based on these observations, prolonged therapeutical approaches using drugs that modify NO availability should be carefully considered.

Pro-Atherogenic Alterations in T-Lymphocyte Subpopulations Related to Acute Hyperglycaemia in Type 2 Diabetic Patients

BACKGROUND

T cells are among the earliest cells to infiltrate the arterial intima during the initial stages of atherosclerosis. Alterations in the peripheral blood lymphocyte distribution might be associated with intensive lymphocytes extravasation and stimulation of atherosclerotic plaque development. Epidemiological data reveal that short-term postprandial hyperglycemia is a significant risk factor for coronary heart disease. Using a parameter that indicates recently-past acute hyperglycemia, 1,5-anhydro-D-glucitol (1,5-AG), the aim of the present study was to elucidate which alterations in peripheral blood T-lymphocytes, if any, are associated with acute hyperglycemia in patients with type 2 diabetes mellitus (DM) and, thus, might be involved in the progression of atherosclerosis.

METHODS AND RESULTS

Measurement of fasting glucose level, glycated hemoglobin A(1c), 1,5-AG, lipid profile and lymphocyte receptors expression (CD3+, CD4+, CD8+, CD8+28+, CD+28 -) was performed in 97 patients with type 2 DM, 23 patients with coronary heart disease, and 15 healthy controls. The mean CD3+, CD4+, CD8+28 - and CD8+28+ lymphocyte counts were significantly higher in the DM patients than in both control groups. Multiple regression analysis revealed that CD4+ and CD8+28- lymphocyte counts primarily were dependent on 1,5-anhydro-D-glucitol plasma levels.

CONCLUSIONS

These results suggest that acute hyperglycemia results in the progression of atherosclerosis in type 2 DM, at least in part through changes in CD4+ and CD8+28- lymphocyte subsets.

Nitric oxide and atherosclerosis: an update

Nitric oxide (NO) is a molecule that has gained recognition as a crucial modulator of vascular disease. NO has a number of intracellular effects that lead to vasorelaxation, endothelial regeneration, inhibition of leukocyte chemotaxis, and platelet adhesion. Endothelium damage induced by atherosclerosis leads to the reduction in bioactivity of endothelial NO synthase (eNOS) with subsequent impaired release of NO together with a local enhanced degradation of NO by increased generation of reactive oxygen species with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Many commonly used vasculoprotective agents have their therapeutic actions through the production of NO. L-Arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. Finally, eNOS gene polymorphism might be an additional risk factor that may contribute to predict cardiovascular events. However, further studies are needed to understand the possible clinical implications of these correlations.

Eptifibatide does not influence lymphocyte activation and CRP levels in patients with undergoing coronary angioplasty

Inhibitors of the IIB-IIIA integrin are widely used to prevent stent thrombosis. Abciximab has been shown to attenuate the inflammatory response in patients undergoing PCI. Herein, we tested the effect of eptifibatide infused during PCI on peripheral lymphocyte activation and CRP levels before, and one month after the procedure showing no noticeable effect. These results may explain the differences in clinical outcome following PCI by use of different IIB-IIIA agents.

Therapeutic potential of nitric oxide donors in the prevention and treatment of atherosclerosis

Well-known risk factors for atherosclerosis include hypercholesterolaemia, hypertension, diabetes, and smoking. These conditions are associated with endothelial dysfunction, which itself is associated with reduced endothelial generation of nitric oxide (NO). This is an overview of the implications of NO generation in atherosclerosis and of the potential therapeutic benefit of drugs which donate NO, such as organic nitrates, nicorandil, and sydnonimines, or those which increase the availability of endogenous NO, such as statins, angiotensin-converting enzyme inhibitors, L-arginine, and tetrahydrobiopterin.

Elevation of asymmetric dimethylarginine in patients with unstable angina and recurrent cardiovascular events

AIMS

We investigated the role of asymmetric dimethylarginine (ADMA) for clinical outcome of patients with unstable angina.

METHODS AND RESULTS

Forty-five patients with stable angina, 36 patients with unstable angina, and 40 healthy controls were included in this study. Coronary artery disease (CAD) patients were prospectively followed for 1 year. ADMA levels were measured at baseline and after 6 weeks using a validated ELISA. Baseline ADMA concentration in controls was significantly lower than in patients with CAD (0.59+/-0.23 vs. 0.76+/-0.17 micromol/L; P<0.001). Patients with unstable angina had significantly higher baseline ADMA levels than patients with stable angina (0.82+/-0.18 vs. 0.73+/-0.15 micromol/L; P=0.01). There was a significant reduction of ADMA levels at 6 weeks after percutaneous coronary intervention (PCI) in patients with unstable angina who experienced no recurrent cardiovascular event (from 0.81+/-0.14 to 0.73+/-0.19 micromol/L; P<0.05). In contrast, patients with unstable angina who had an event showed no significant decrease in ADMA at 6 weeks. Actuarial survival analysis showed a significantly higher event rate in patients with persistently elevated ADMA plasma concentrations.

CONCLUSION

ADMA is significantly elevated in patients with unstable angina. A reduced ADMA level at 6 weeks after PCI may indicate a decreased risk of recurrent cardiovascular events.