Wael Hamouda

Troglitazone Reduces Reactive Oxygen Species Generation by Leukocytes and Lipid Peroxidation and Improves Flow-Mediated Vasodilatation in Obese Subjects

Because troglitazone has been shown to have antioxidant properties, we investigated whether troglitazone administration to obese subjects causes a reduction in (1) reactive oxygen species (ROS) generation by polymorphonuclear leukocytes (PMNLs) and mononuclear cells (MNCs) and (2) lipid peroxidation as reflected in the plasma concentrations of 9-hydroxyoctadecadienoic acid (9-HODE) and 13-hydroxyoctadecadienoic acid (13-HODE). Seven obese subjects were given 400 mg/d troglitazone for 4 weeks. Blood samples were obtained before troglitazone administration and at weekly intervals thereafter. Insulin concentrations fell significantly at week 1 and remained low at weeks 2 and 4 (P <0.001). ROS generation by PMNLs fell to 77.6±25.1% of the basal at week 1 and 47.9±41.1% at week 4 (P <0.001). ROS generation by MNCs fell to 59.8±15.7% of the basal at week 1 and 35.1±17.6% at week 4 (P <0.001). 9-HODE and 13-HODE concentrations fell significantly from 787.4±52.4 and 713.1±44.7 pg/mL to 720.4±66.7 (P <0.004) and 675.2±65.0 pg/mL (P <0.01) after 4 weeks, respectively. Postischemic dilatation of the brachial artery was measured by ultrasonography. The mean percent dilatation after forearm ischemia before and after troglitazone was 5.5±3.01% and 8.75±3.37% (P <0.02), respectively. The percent increase in diameter after nitroglycerin was 17.08±1.18% before troglitazone, whereas it was 18.9±1.91% (P <0.02) after troglitazone. We conclude that troglitazone has a potent and rapid biological inhibitory effect on ROS generation by PMNLs and MNCs and that it inhibits lipid peroxidation significantly. These changes are associated with a significant improvement in postischemic flow-mediated vasodilation in the brachial artery over a relatively short period of 4 weeks.

Carvedilol Inhibits Reactive Oxygen Species Generation by Leukocytes and Oxidative Damage to Amino Acids

BACKGROUND The purpose of this study was to test whether carvedilol has an antioxidant effect in humans in vivo. METHODS AND RESULTS We administered 3.125 mg of carvedilol twice daily to normal subjects for 1 week. ROS generation by polymorphonuclear leukocytes and mononuclear cells fell from 314+/-183.43 and 303+/-116 mV to 185+/-157 and 189+/-63 mV (P<0.025), respectively. m-Tyrosine fell from 4.24+/-0.99 to 4.03+/-0.97 ng/mL (P=0.01), and o-tyrosine fell from 4.59+/-1.10 to 4.24+/-0.99 ng/mL (P=0.004) in the absence of a change in phenylalanine concentrations. CONCLUSIONS We conclude that carvedilol significantly inhibits ROS generation by leukocytes and oxidative conversion of phenylalanine to m- and o-tyrosine.

Effect of dexamethasone on reactive oxygen species generation by leukocytes and plasma interleukin‐10 concentrations: A pharmacodynamic study

After the demonstration that hydrocortisone inhibits reactive oxygen species (ROS) generation by leukocytes in vivo in a highly predictable manner, we investigated the effect of dexamethasone at a dose of 4 mg, which is thought to be roughly equivalent to 100 mg hydrocortisone. We also tested the hypothesis that dexamethasone may increase the plasma concentration of interleukin‐10 (IL‐10), an immunomodulatory cytokine that inhibits TH 1 cells. Dexamethasone (4 mg given intravenously) markedly inhibited ROS generation by mononuclear cells and polymorphonuclear leukocytes. The onset of the effect on polymorphonuclear leukocytes occurred at 1 hour (76.3% ± 9.3% of basal value), and the peak effect occurred at 4 hours (22.9% ± 6.4% of basal value), with a significant inhibition still persistent at 8 hours (51.3% ± 14.3% of basal value; F = 66.7; P < .001). ROS generation was restored to baseline at 24 hours (97.6% ± 9.5%). The inhibitory effect of dexamethasone on mononuclear cells was 78.3% ± 9.5% of baseline at 1 hour, 11.4% ± 6.6% at 4 hours, 30.3% ± 14.1% at 8 hours, and 102.3% ± 18% at 24 hours (F = 66.5; P < .001). The peak inhibitory effect of dexamethasone on mononuclear cells (11.4% ± 6.6%) was significantly greater (P < .05) than that on polymorphonuclear leukocytes (22.9% ± 6.4%). Plasma IL‐10 concentrations increased consistently from 4.8 ± 1.8 pg/mL within 1 hour of dexamethasone injection and peaked at 4 hours (8.8 ± 2.3 pg/mL), declining to baseline at 8 hours (F = 4.26; P < .004). Dexamethasone (and possibly other glucocorticoids) therefore exerts its immunosuppressive and anti‐inflammatory effects by inhibiting ROS generation by leukocytes and by increasing the plasma concentrations of IL‐10.

Heparin Inhibits Reactive Oxygen Species Generation by Polymorphonuclear and Mononuclear Leucocytes

To examine the hypothesis that heparin may affect leukocyte function and that it may have anti-inflammatory properties, we investigated the effect of heparin on reactive oxygen species (ROS) generation by leucocytes. Heparin was injected intravenously at a dose of 10000 units into eight normal subjects. Blood samples were collected from the antecubital vein sequentially, prior to and following heparin at 0, 0.5, 1, 2, and 4 hours. ROS generation was inhibited significantly by polymorphonuclear cells (PMNL) at 0.5, 1, and 2 hours and returned to baseline level at 4 hours. Similarly, ROS generation was inhibited markedly by mononuclear cells (MNC) at 0.5 hours, with a peak inhibition at 1 hour; it returned to baseline level by 4 hours. The maximum inhibition of ROS generation by PMNL was 57.3+/-19% of the basal, while that by MNC was 56.4+/-11% of the basal. Since ROS are proinflammatory and cause tissue damage, it is possible that heparin may have an anti-inflammatory effect in vivo, apart from its antithrombotic effect. Since ROS also bind to nitric oxide (NO) and reduce the bioavailability of NO, heparin may indirectly increase the bioavailability of NO and thus act as a vasodilator. This effect of heparin may be of particular relevance to its use in unstable angina and following thrombolysis in acute myocardial infarction in preventing reperfusion injury.

Hydrocortisone-induced inhibition of reactive oxygen species by polymorphonuclear neutrophils.

OBJECTIVE To determine whether hydrocortisone given intravenously inhibits reactive oxygen species (ROS) generation by polymorphonuclear neutrophils (PMNLs) in vivo and, if so, to describe the pharmacodynamics of this effect. DESIGN A prospective, open label study in normal subjects. SETTING A clinical research unit of a tertiary referral center for diabetes and endocrinology. PATIENTS Eight normal subjects (age range, 2450 yrs). INTERVENTION An indwelling cannula was inserted into the antecubital vein. Sequential blood samples were obtained from the cannula just before, and after, the intravenous injection of hydrocortisone (100 mg) at 1, 2, 4, 8, and 24 hrs. MEASUREMENTS AND MAIN RESULTS ROS generation by PMNLs and mononuclear cells (MNCs) was assayed as previously observed in a chemiluminometer. ROS generation by PMNLs and MNCs was inhibited by hydrocortisone at 1 hr; this effect peaked at 2 hrs and began to recover by 4 hrs; ROS generation had recovered to the baseline by 24 hrs. Although the pharmacodynamic effect of hydrocortisone on PMNLs and MNCs was similar, the peak inhibition was significantly greater for PMNLs (26% of basal vs. 43% of basal, p<.02) than MNCs. CONCLUSIONS There is a marked, consistent, inhibition of ROS generation by PMNLs, which parallels that of MNCs after intravenous hydrocortisone. The pharmacodynamics of this effect are consistent with our current clinical practices.

Nadolol inhibits reactive oxygen species generation by leukocytes and linoleic acid oxidation

We studied the effect of short-term nadolol administration on the reactive oxygen species (ROS) generation by polymorphonuclear leukocytes and mononuclear cells in 8 normal subjects. At a oral dose of 40 mg/day for 5 days, nadolol produced a decrease in the ROS generation by leukocytes. ROS generation by polymorphonuclear leukocytes decreased by 38% from 134 +/- 44 mV at baseline to 83 +/- 34 mV after 5 days (p = 0.005), and ROS generation by mononuclear cells decreased by 33% from 174 +/- 69 mV at baseline to 117 +/- 55 mV after 5 days (p = 0.015). There was also a significant reduction in linoleic acid oxidation as reflected by the lower levels of 9- and 13- hydroxy-octadecadienoic acid after 5 days. There was no change in the plasma thiobarbituric acid-reacting substances, a less sensitive index of oxidative damage to lipids. There was also no significant change in the levels of metatyrosine and orthotyrosine, which are known indexes of oxidative damage to amino acids and proteins. The absence of a significant change in metatyrosine, orthotyrosine, and thiobarbituric acid-reacting substances may reflect the short duration of nadolol administration and the decreased ROS load. Because ROS may induce lipid peroxidation, this inhibitory effect of nadolol on ROS generation by leukocytes and linoleic acid oxidation may inhibit low-density lipoprotein oxidation and thus atherogenesis. This effect may partly explain the favorable outcomes observed in patients with coronary artery disease on long-term beta-blocker therapy.