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Biomedical subjects

I Jialal

Publications and source records attributed to I Jialal.

At least 19 recordsLinked to original sources
PubMed2001

Heterozygosity for the mouse Apex gene results in phenotypes associated with oxidative stress.

Apurinic/apyrimidinic endonuclease is a key enzyme in the process of base excision repair, required for the repair of spontaneous base damage that arises as a result of oxidative damage to DNA. In mice, this endonuclease is coded by the Apex gene, disruption of which is incompatible with embryonic life. Here we confirm the embryonic lethality of Apex-null mice and report the phenotypic characterization of mice that are heterozygous mutants for the Apex gene (Apex+/-). We show that Apex heterozygous mutant cells and animals are abnormally sensitive to increased oxidative stress. Additionally, such animals manifest elevated levels of oxidative stress markers in serum, and we show that dietary supplementation with antioxidants restores these to normal levels. Apex+/- embryos and pups manifest reduced survival that can also be partially rescued by dietary supplementation with antioxidants. These results are consistent with a proposed role for this enzyme in protection against the deleterious effects of oxidative stress and raise the possibility that humans with heterozygous mutations in the homologous HAP1 gene may be at increased risk for the phenotypic consequences of oxidative stress in cells.

Adenocarcinoma, Papillary↗
PubMed2001

Effects of low-dose aspirin on serum C-reactive protein and thromboxane B2 concentrations: a placebo-controlled study using a highly sensitive C-reactive protein assay.

OBJECTIVES: We performed a placebo-controlled study to evaluate the effect of low-dose aspirin on serum C-reactive protein (CRP) levels. BACKGROUND: Elevated circulating concentrations of CRP, an inflammatory marker, increase the risk of thrombotic cardiovascular diseases such as myocardial infarction (MI). Moreover, low-dose aspirin therapy has been reported to be more effective in preventing MI in men with higher CRP levels than it is in those with lower levels, raising the possibility that aspirin prevents thrombosis by reducing vascular inflammation. The effect of low-dose aspirin therapy on serum CRP levels in men has been addressed recently, but the results of the two studies conflict. METHODS: Effects of aspirin (81 mg every day or 325, 81 or 40 mg every-third-day given for 31 days) on serum CRP, using a highly-sensitive assay, and on serum platelet-cyclo-oxygenase (COX)-1-derived thromboxane (Tx) B2 concentrations were studied simultaneously in 57 healthy volunteers (30 men and 27 women). RESULTS: Trough platelet COX-1-derived serum Tx B2 concentrations decreased by 100% with daily aspirin and by 90%, 84% and 78% with 325, 81 and 40 mg aspirin every-third-day (p < 0.001). However, there were no significant changes in serum CRP levels from baseline with daily low-dose aspirin therapy, with any of the every-third-day aspirin regimens or with placebo treatment. CONCLUSIONS: Low doses of aspirin that markedly inhibit platelet COX-1 activity, as manifested by a profound decline in platelet-derived serum Tx B2 concentrations, have no detectable effect on serum CRP levels in healthy men and women.

Adult↗
PubMed2001

Effect of hydroxymethyl glutaryl coenzyme a reductase inhibitor therapy on high sensitive C-reactive protein levels.

BACKGROUND: Prospective studies indicate that baseline levels of C-reactive protein (CRP), the prototypic marker of inflammation, are associated with an increased risk for cardiovascular events. Limited studies have examined therapies that influence high-sensitive CRP (hs-CRP) levels, especially in hyperlipidemic patients. Thus, we tested the effects of 3 hydroxymethyl glutaryl coenzyme A reductase inhibitors (statins), simvastatin (20 mg/d), pravastatin (40 mg/d), and atorvastatin (10 mg/d), on levels of hs-CRP in a randomized, double-blind, crossover trial of 22 patients with combined hyperlipidemia (LDL cholesterol >130 mg/dL and triglycerides of 200 to 600 mg/dL). METHODS AND RESULTS: After 6 weeks of an American Heart Association Step 1 diet, fasting blood samples were drawn at baseline and after 6 weeks of therapy with each drug. hs-CRP levels were significantly decreased after treatment with all 3 statins compared with baseline (median values: baseline, 2.6 mg/L; atorvastatin, 1.7 mg/L; simvastatin, 1.7 mg/L; and pravastatin, 1.9 mg/L; P<0.025). The reductions obtained with the 3 statins were similar. In addition, there was no significant effect on either plasma interleukin-6 or interleukin-6 soluble receptor levels. There was no relationship between reductions in hs-CRP and LDL cholesterol. CONCLUSIONS: Pravastatin, simvastatin, and atorvastatin significantly decreased levels of hs-CRP. These data support an anti-inflammatory effect of these drugs.

Atorvastatin↗
PubMed2001

Low-density lipoprotein (LDL)-induced monocyte-endothelial cell adhesion, soluble cell adhesion molecules, and autoantibodies to oxidized-LDL in chronic renal failure patients on dialysis therapy.

Premature atherosclerosis is a major cause of morbidity and mortality in chronic renal failure patients undergoing dialysis. In this study, we compared autoantibodies to oxidized low-density lipoprotein (OX-LDL), soluble cell adhesion molecules (CAMs), and the effect of both LDL and OX-LDL on monocyte endothelial cell adhesion in chronic renal failure patients on hemodialysis (HD, n = 16) and peritoneal dialysis (PD, n = 17) compared with matched healthy control subjects (C, n = 17). In addition, we studied the effect of supplementation with RRR-alpha-tocopherol (AT) 800 IU/d for 12 weeks on the above measures. LDL and OX-LDL induced adhesion of U937 cells to cultured endothelium, soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intracellular adhesion molecule-1 (sICAM-1), and soluble E-selectin (sE-selectin); autoantibodies to OX-LDL and markers of lipid peroxidation were determined before and after AT supplementation. Native LDL from PD patients induced greater monocyte-endothelial cell adhesion than LDL from C subjects (43.8% +/- 17.0% v25.3% +/- 17.7%, respectively, P = .0028). OX-LDL from chronic renal failure patients on both PD and HD stimulated greater adhesion than OX-LDL from the C subjects (68.0% +/- 18.5% and 57.6% +/- 15.1% v 40.9% +/- 17.3%, respectively, P < .01); OX-LDL from PD patients induced greater adhesion than that from HD patients (P < .01). Plasma methylglyoxal levels were significantly increased in both HD and PD groups, with higher levels in the HD group. Chronic renal failure patients on HD and PD also had higher levels of plasma sVCAM-1 and sE-selectin than C subjects (P < .01), indicating endothelial activation. Titers of autoantibodies to OX-LDL were not elevated in renal failure patients. Supplementation with AT 800 IU/d for 12 weeks, while resulting in significant enrichment with AT in LDL, did not have a significant effect on any of the parameters studied. This study makes the novel observation that the LDL of chronic renal failure patients on HD and PD appears to be potentially more atherogenic, since it induces greater monocyte-endothelial cell adhesion.

Adult↗
PubMed2001

The effect of alpha-tocopherol on monocyte proatherogenic activity.

Atherosclerosis is the leading cause of morbidity and mortality in Westernized populations. The monocyte is a crucial cell in the genesis of the atherosclerotic lesion and is present during all stages of atherosclerosis. alpha-Tocopherol (AT) is the most active component of the vitamin E family and is the principal and most potent lipid-soluble antioxidant in plasma and LDL. With regard to monocyte function, AT supplementation (1200 IU/d) has been shown to decrease release of reactive oxygen species, lipid oxidation, release of cytokines such as interleukin-1ss (IL-1ss) and tumor necrosis factor-alpha (TNF-alpha) and decrease adhesion of monocytes to human endothelium. The mechanism of inhibition of superoxide and lipid oxidation by monocytes appears to be via inhibition of protein kinase C (PKC), the decrease in IL-1ss and TNF-alpha release by inhibition of 5-lipoxygenase and the inhibition of monocyte-endothelial cell adhesion via decrease in adhesion molecules on monocytes, CD11b and VLA-4 and by decreasing DNA-binding activity of nuclear transcription factor kappaB. Thus, in addition to the decrease in oxidative stress resulting from AT supplementation, as evidenced by decreased F(2)-isoprostanes and LDL oxidizability, AT is anti-inflammatory and exerts beneficial antiatherogenic effects on cells crucial in atherogenesis such as monocytes.

Animals↗
PubMed2001

Is there a vitamin E paradox?

In addition to epidemiologic studies that suggest a benefit for high intakes of alpha-tocopherol, studies of supplementation in humans have clearly shown that alpha-tocopherol decreases lipid peroxidation, platelet aggregation, and functions as a potent anti-inflammatory agent. In the five large prospective clinical trials with alpha-tocopherol therapy, four have shown a beneficial effect on cardiovascular end-points (two studies on a primary end-point and two studies on other cardiovascular end-points). Thus, the totality of evidence based on the epidemiologic data, in-vitro studies and animal models, and the clinical trials appears to support a benefit for alpha-tocopherol supplementation in patients with pre-existing cardiovascular disease. However, definitive recommendations must await ongoing clinical trials.

Adult↗
PubMed2001

Effect of statin therapy on remnant lipoprotein cholesterol levels in patients with combined hyperlipidemia.

Clinical trials with statins have demonstrated significant reductions in cardiovascular events. Remnant lipoproteins are independent predictors of cardiovascular events. Because of the paucity of data on the effect of statins on remnant lipoproteins, we tested the effect of pravastatin, simvastatin, and atorvastatin on remnant lipoprotein cholesterol (RLP-C) levels in a randomized crossover study in patients with combined hyperlipidemia. After a 6-week diet phase, patients (n=22) were randomized to pravastatin (40 mg/d), simvastatin (20 mg/d), or atorvastatin (10 mg/d) for 6 weeks, with a 3-week washout between each drug. All 3 drugs significantly decreased total and low density lipoprotein (LDL) cholesterol (P<0.001). Mean reduction in LDL cholesterol with pravastatin, simvastatin, and atorvastatin was 21%, 29%, and 32%, respectively. None of the drugs affected high density lipoprotein cholesterol levels. Median levels of triglycerides were significantly reduced with simvastatin (26%, P=0.001) and atorvastatin (24%, P=0.0001) but not with pravastatin (9%, P=0.18). Non-high density lipoprotein cholesterol decreased significantly with all 3 statins (20%, 29%, and 32% with pravastatin, simvastatin, and atorvastatin, respectively; P<0.001). Median RLP-C levels were significantly reduced with simvastatin (6%, P<0.05) and atorvastatin (25.9%, P<0.001) but not with pravastatin (2.9%, P=0.58). Thus, atorvastatin and simvastatin, in addition to reducing LDL cholesterol and triglyceride levels, significantly reduced RLP-C levels. This could be another potential mechanism to explain their cardiovascular benefits.

Adult↗
PubMed2001

Alpha-tocopherol and atherosclerosis.

Cardiovascular disease is the leading cause of morbidity and mortality in the Western world. There is compelling evidence incriminating oxidative stress in the pathogenesis of the atherosclerotic lesion. Several lines of evidence suggest that antioxidants, especially alpha-tocopherol, have potential beneficial effects with regard to cardiovascular disease. In vitro, alpha-tocopherol has been shown to inhibit platelet adhesion and aggregation and smooth muscle cell proliferation, exert anti-inflammatory effects on monocytes, and improve endothelial function. Also, supplementation with alpha-tocopherol has been shown to decrease lipid peroxidation, platelet aggregation, and pro-inflammatory activity of monocytes. However, clinical trials with alpha-tocopherol supplementation to date have been equivocal. Thus, although mounting in vitro evidence and animal models provide a sound scientific basis for alpha-tocopherol supplementation, further clinical trials are required before a definitive recommendation can be made with respect to the primary and secondary prevention of heart disease.

Animals↗
PubMed2001

Inflammation and atherosclerosis: the value of the high-sensitivity C-reactive protein assay as a risk marker.

C-reactive protein (CRP) is a prototypic marker of inflammation. Numerous prospective studies in healthy volunteers have confirmed that high-sensitivity CRP (hsCRP) predicts cardiovascular events (CVEs), and hsCRP seems additive to an elevated total cholesterol level and a total/high-density lipoprotein cholesterol ratio in men and women in predicting risk. In smokers and people with metabolic syndrome, hsCRP levels are elevated; in elderly people, there seems to be a relationship between hsCRP and CVEs and mortality. Several properties of CRP make it proatherogenic; however; pending further studies, it should be considered as a risk marker. In people with acute coronary syndromes, hsCRP measurement may be valuable. Elevated levels in the highest quantile seem to predict greater mortality and poorer prognosis in patients with unstable angina and myocardial infarction (MI). While hsCRP is a strong independent predictor of risk of future MI, stroke, peripheral arterial disease, and vascular death, the validity of hsCRP as a risk marker needs to be assessed in all populations. Weight loss, statin drugs, aspirin, and high-dose alpha tocopherol therapy could affect hsCRP. It has its greatest validity as an adjunctive measure in the primary prevention of cardiovascular disease.

Arteriosclerosis↗
PubMed2001

Alpha-tocopherol decreases CD36 expression in human monocyte-derived macrophages.

Cholesterol-laden macrophages are the hallmark of atherogenesis. The class B scavenger receptor, CD36, binds oxidized low density lipoprotein (OxLDL), is found in atherosclerotic lesions, and is upregulated by OxLDL. We tested the effects of alpha-tocopherol (AT) enrichment of human monocyte-derived macrophages on CD36 expression and cholesteryl ester accumulation. Monocytes isolated from normal volunteers were cultured into macrophages. Macrophages were enriched overnight with various doses of AT (25, 50, and 100 microM). LDL from normal volunteers was oxidized or acetylated (AcLDL) and incubated with macrophages for 48 h at a concentration of 50 or 100 microg/ml. CD36 expression was assessed by flow cytometry. Quantitative analysis of scavenger receptor class A (SR-A) activity was performed with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanide perchlorate (DiI)-labeled LDL. CD36 expression was maximal after 8;-10 days of culture. AT (> or =50 microM) significantly decreased CD36 expression upregulated by OxLDL and AcLDL (P < 0.01). Other antioxidants (beta- or gamma-tocopherol) or protein kinase C inhibitors failed to decrease CD36 expression. Concomitantly, DiI-AcLDL and DiI-OxLDL uptake was significantly decreased after AT treatment (P < 0.001). Cholesteryl ester accumulation was significantly decreased after AT enrichment (AcLDL + AT, 77% inhibition; OxLDL + AT, 42% inhibition). In conclusion, AT decreases both CD36 and SR-A expression and cholesteryl ester accumulation in human macrophages. This provides additional scientific support for the antiatherogenic properties of AT.

Antioxidants↗
PubMed2001

Divergence between LDL oxidative susceptibility and urinary F(2)-isoprostanes as measures of oxidative stress in type 2 diabetes.

BACKGROUND: Oxidative stress is pivotal in atherogenesis. Although the most widely used indirect assay to quantify oxidative stress is LDL oxidative susceptibility, direct assays such as urinary F(2)-isoprostanes have shown great promise. METHODS: We evaluated the utility of both a direct measure of oxidative stress (urinary F(2)-isoprostanes) and an indirect measure of copper-catalyzed, LDL oxidation in a model of increased oxidative stress (diabetes). We also evaluated an enzyme immunoassay (EIA) method for urinary F(2)-isoprostanes with a gas chromatography-mass spectrometry method. RESULTS: Excellent intraassay and interassay CVs of <4% were obtained with our EIA method. A good correlation was obtained between the two methods (r = 0.80; n = 68) of F(2)-isoprostane measurement. An excellent correlation for F(2)-isoprostane concentrations was obtained between a timed collection vs 24-h urine (r = 0.96; n = 46). Baseline F(2)-isoprostane concentrations by EIA were significantly higher in both type 2 diabetics with and without macrovascular complications compared with controls (P <0.001). Supplementation with alpha-tocopherol led to a significant reduction in F(2)-isoprostane concentrations in all diabetic patients compared with baseline values (2.51 +/- 1.76 compared with 1.69 +/- 1.32 ng/mg creatinine; P <0.001). There were no significant differences in LDL oxidation in both diabetic groups compared with controls. alpha-Tocopherol supplementation led to significant increases in the lag phase of oxidation as measured by 3 indices in all groups. CONCLUSIONS: The measurement of urinary F(2)-isoprostanes provides a direct measure of in vivo lipid peroxidation and oxidative stress and appears to be superior to an indirect measure, e.g., LDL oxidative susceptibility, in type 2 diabetes.

Diabetes Mellitus, Type 2↗
PubMed2000

Studies of LDL oxidation following alpha-, gamma-, or delta-tocotrienyl acetate supplementation of hypercholesterolemic humans.

In vitro tocotrienols (T3s) have potent vitamin E antioxidant activity, but unlike tocopherols can inhibit cholesterol synthesis by suppressing 3-hydroxy-3-methyl-glutarylCoA (HMG-CoA) reductase. Because hypercholesterolemia is a major risk factor for coronary artery disease and oxidative modification of low-density lipoprotein (LDL) may be involved in atherogenesis, we investigated whether daily supplements of placebo, or alpha-, gamma-, or delta- (alpha-, gamma-, or delta-) tocotrienyl acetates would alter serum cholesterol or LDL oxidative resistance in hypercholesterolemics in a double-blind placebo controlled study. Subjects were randomly assigned to receive placebo (n = 13), alpha- (n = 13), gamma- (n = 12), or delta- (n = 13) tocotrienyl acetate supplements (250 mg/d). All subjects followed a low-fat diet for 4 weeks, then took supplements with dinner for the following 8 weeks while still continuing diet restrictions. Plasma alpha- and gamma-tocopherols were unchanged by supplementation. Plasma T3s were undetectable initially and always in the placebo group. Following supplementation in the respective groups plasma concentrations were: alpha-T3 0.98 +/- 0.80 micromol/l, gamma-T3 0.54 +/- 0.45 micromol/l, and delta-T3 0.09 +/- 0.07 micromol/l. Alpha-T3 increased in vitro LDL oxidative resistance (+22%, p <.001) and decreased its rate of oxidation (p <. 01). Neither serum or LDL cholesterol nor apolipoprotein B were significantly decreased by tocotrienyl acetate supplements. This study demonstrates that: (i) tocotrienyl acetate supplements are hydrolyzed, absorbed, and detectable in human plasma; (ii) tocotrienyl acetate supplements do not lower cholesterol in hypercholesterolemic subjects on low-fat diets; and (iii) alpha-T3 may be potent in decreasing LDL oxidizability.

Adult↗
PubMed2000

Alpha tocopherol supplementation decreases serum C-reactive protein and monocyte interleukin-6 levels in normal volunteers and type 2 diabetic patients.

Type 2 diabetic subjects have an increased propensity to premature atherosclerosis. Alpha tocopherol (AT), a potent antioxidant, has several anti-atherogenic effects. There is scanty data on AT supplementation on inflammation in Type 2 diabetic subjects. The aim of the study was to test the effect of RRR-AT supplementation (1200 IU/d) on plasma C-reactive protein (CRP) and interleukin-6 (IL-6) release from activated monocyte in Type 2 diabetic patients with and without macrovascular complications compared to matched controls. The volunteers comprised Type 2 diabetic subjects with macrovascular disease (DM2-MV, n = 23), Type 2 diabetic subjects without macrovascular complications (DM2, n = 24), and matched controls (C, n = 25). Plasma high sensitive CRP (Hs-CRP) and Monocyte IL-6 were assayed at baseline, following 3 months of supplementation and following a 2 month washout phase. DM2-MV subjects have elevated HsCRP and monocyte IL-6 compared to controls. AT supplementation significantly lowered levels of C-reactive protein and monocyte interleukin-6 in all three groups. In conclusion, AT therapy decreases inflammation in diabetic patients and controls and could be an adjunctive therapy in the prevention of atherosclerosis.

Antioxidants↗
PubMed2000

Low-density lipoprotein postsecretory modification, monocyte function, and circulating adhesion molecules in type 2 diabetic patients with and without macrovascular complications: the effect of alpha-tocopherol supplementation.

BACKGROUND: Although diabetes confers an increased propensity toward accelerated atherogenesis, data are lacking on monocyte activity in type 2 diabetic patients with (DM2-MV) and without (DM2) macrovascular disease compared with control subjects. Thus, we tested whether (1) postsecretory modifications of LDL (glycation and oxidation), monocyte proatherogenic activity, and circulating levels of soluble cell adhesion molecules (sCAMs) are more pronounced in DM2-MV than in DM2 and control subjects and (2) RRR-alpha-tocopherol (AT) therapy, 1200 IU/d for 3 months, has a similar effect in the 3 groups (n=25 per group). METHODS AND RESULTS: Although LDL glycation was increased in both diabetic groups compared with control subjects, AT therapy had no significant effect on glycation. AT therapy significantly decreased LDL oxidizability in all 3 groups. Diabetic monocytes released significantly more superoxide anion (O(2)(-)) and interleukin-1beta (IL-1beta) and exhibited greater adhesion to endothelium than control subjects. AT therapy significantly decreased the release of O(2)(-), IL-1beta, tumor necrosis factor-alpha, and monocyte-endothelium adhesion in all 3 groups. There was no significant difference between the 2 diabetic groups for any of the above parameters. sICAM levels were significantly elevated in both diabetic groups compared with controls. AT therapy resulted in a significant decrease in sCAMs. CONCLUSIONS: This is the first demonstration of increased IL-1beta secretion and increased adhesion of monocytes to endothelium from normotriglyceridemic diabetic subjects and of decreased monocyte activity and sCAMs with AT therapy in diabetic subjects with and without macrovasculopathy.

Aged↗