Collagenase Type I and Probucol-Loaded Nanoparticles Penetrate the Extracellular Matrix to Target Hepatic Stellate Cells for Hepatic Fibrosis Therapy

Hepatic fibrosis is a common pathological process in chronic liver diseases, characterized by excessive reactive oxygen species (ROS), activated hepatic stellate cells (HSCs), and massive synthesis of extracellular matrix (ECM), which are important factors in the development of liver cirrhosis, liver failure, and liver cancer. During the development of hepatic fibrosis, ECM collagen produced by activated HSCs significantly hinders medication delivery to targeted cells and reduces the efficiency of pharmacological therapy. In this study, we designed a multifunctional hyaluronic acid polymeric nanoparticle (HA@PRB/COL NPs) based on autophagy inhibitor probucol (PRB) and collagenase type I (COL) modification, which could enhance ECM degradation and accurately target HSCs through specificity binding CD44 receptor in hepatic fibrosis therapy. Upon encountering excessive collagen I-deposition formed barrier, HA@PRB/COL NPs performed the nanodrill-like function to effectively degrade pericellular collagen I, leading to greater ECM penetration and prominent HSCs internalization capacity of delivered PRB. In mouse hepatic fibrosis model, HA@PRB/COL NPs were efficiently delivered to HSCs through binding CD44 receptor to achieve efficient accumulation in fibrotic liver. Further, we showed that HA@PRB/COL NPs executed the optimal anti-fibrotic activity by inhibiting autophagy and activation of HSCs. In conclusion, our novel dual-functional co-delivery system with degrading fibrotic ECM collagen and targeting activated HSCs exhibits great potentials in the treatment of hepatic fibrosis in clinic. STATEMENT OF SIGNIFICANCE: The excess release of extracellular matrix (ECM) such as collagen in hepatic fibrosis hinders medication delivery and decreases the efficiency of pharmacological drugs. We aimed to develop a nano-delivery carrier system with protein hydrolyzed surfaces and further encapsulated an autophagy inhibitor (PRB) to enhance fibrosis-related ECM degradation-penetration and hepatic stellate cells (HSCs) targeting in hepatic fibrosis niche (HA@PRB/COL NPs). The COL of HA@PRB/COL NPs successfully worked as a scavenger to promote the digestion of the ECM collagen I barrier for deeper penetration into fibroid liver tissue. It also accurately targeted HSCs through specifically binding to the CD44 receptor and subsequently released PRB to inhibit autolysosome and ROS generation, thus preventing HSCs activation. Our HA@PRB/COL NPs system provided a promising therapeutic strategy for hepatic fibrosis in a clinic setting.

The therapeutic potential of probucol and probucol analogues in neurodegenerative diseases

Neurodegenerative disorders present complex pathologies characterized by various interconnected factors, including the aggregation of misfolded proteins, oxidative stress, neuroinflammation and compromised blood-brain barrier (BBB) integrity. Addressing such multifaceted pathways necessitates the development of multi-target therapeutic strategies. Emerging research indicates that probucol, a historic lipid-lowering medication, offers substantial potential in the realm of neurodegenerative disease prevention and treatment. Preclinical investigations have unveiled multifaceted cellular effects of probucol, showcasing its remarkable antioxidative and anti-inflammatory properties, its ability to fortify the BBB and its direct influence on neural preservation and adaptability. These diverse effects collectively translate into enhancements in both motor and cognitive functions. This review provides a comprehensive overview of recent findings highlighting the efficacy of probucol and probucol-related compounds in the context of various neurodegenerative conditions, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and cognitive impairment associated with diabetes.

Probucol treatment after traumatic brain injury activates BDNF/TrkB pathway, promotes neuroregeneration and ameliorates functional deficits in mice

BACKGROUND AND PURPOSE

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide, yet pharmacotherapies for TBI are currently lacking. Neuroregeneration is important in brain repair and functional recovery. In this study, probucol, a cholesterol-lowering drug with established safety profiles, was examined for its therapeutic effects and neuroregenerative actions in TBI.

EXPERIMENTAL APPROACH

Male mice were subjected to the controlled cortical impact model of TBI, followed by daily administration of probucol. Neurological and cognitive functions were evaluated. Histological analyses of the neocortex and hippocampus were performed to detect the lesion, dendritic degeneration (microtubule-associated protein 2), synaptic density (synaptophysin), neurogenesis (doublecortin), brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) activation. Involvement of BDNF/TrkB pathway in probucol-mediated effects was examined in primary cultures of cortical neurons.

KEY RESULTS

Probucol reduced brain lesion volume, enhanced the recovery of body symmetry, improved motor function and attenuated memory dysfunction after TBI. Meanwhile, probucol promoted post-injury dendritic growth and synaptogenesis and increased hippocampal proliferating neuronal progenitor cells, along with the formation as well as the survival of newborn neurons. Moreover, probucol enhances BDNF expression and TrkB activation. In vitro, probucol promoted neurite outgrowth, which was inhibited by a selective TrkB antagonist ANA-12.

CONCLUSIONS AND IMPLICATIONS

Probucol enhanced functional restoration and ameliorated cognitive impairment after TBI by promoting post-injury neuronal remodelling and neurogenesis. Increased activation of BDNF/TrkB pathway by probucol, at least in part, contributed to the neuroregenerative effects of probucol. Together, it may be promising to repurpose probucol for TBI.

Preventing contrast-induced acute kidney injury with probucol and hydration in patients with coronary heart disease: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Preventing contrast-induced acute kidney injury (CI-AKI) is critical because of its association with poor clinical outcomes, including extended hospital stays and increased mortality. The effects of probucol on preventing CI-AKI have been controversial. Therefore, this systematic review and meta-analysis evaluated the influence of probucol combined with hydration on the CI-AKI risk in patients with coronary heart disease undergoing coronary angiography (CAG) or percutaneous coronary intervention (PCI).

METHODS

We retrieved data from the following databases from their inception to May 29, 2022: PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Chinese Biomedical Literature Database (Sinomed), Wanfang Database, and Chinese Scientific Journal Database. The methodological quality of the trials was assessed following the Cochrane Handbook guidelines, and Review Manager 5.3 and Stata 14.0 software were used for the data analysis.

RESULTS

We included 14 trials comprising 3306 patients in the analysis. All included trials reported the CI-AKI incidence rate (the primary outcome). Probucol with hydration significantly reduced the CI-AKI incidence compared to hydration alone (odds ratio [OR]: 0.33, 95% confidence interval [CI]: 0.25-0.44, P < .001). Subgroup analyses were performed based on the contrast medium type (iso-osmolality vs low-osmolality contrast medium [LOCM]) and volume (less than or more than 200 mL); the effects of probucol with hydration versus hydration-only on CI-AKI were comparable within each subgroup. Additionally, the serum creatinine (Scr) concentration 24 hours, 48 hours, and 72 hours and the estimated glomerular filtration rate (eGFR) 72 hours after contrast exposure were better in the probucol with hydration group than the hydration-only group. Finally, major clinical adverse events and adverse drug reactions were comparable between the probucol with hydration and hydration-only groups.

CONCLUSION

Probucol with hydration decreases the CI-AKI incidence compared to hydration only in patients with coronary heart disease undergoing CAG or PCI. However, more high-quality, large-sample, multicenter randomized trials are needed to confirm this conclusion.

Research and Progress of Probucol in Nonalcoholic Fatty Liver Disease

With the development of the social economy over the last 30 years, non-alcoholic fatty liver disease (NAFLD) is affected by unhealthy living habits and eating styles and has gradually become an increasingly serious public health problem. It is very important to investigate the pathogenesis and treatment of NAFLD for the development of human health. Probucol is an antioxidant with a bis-phenol structure. Although probucol is a clinically used cholesterol-lowering and antiatherosclerosis drug, its mechanism has not been elucidated in detail. This paper reviews the chemical structure, pharmacokinetics and pharmacological research of probucol. Meanwhile, this paper reviews the mechanism of probucol in NAFLD. We also analyzed and summarized the experimental models and clinical trials of probucol in NAFLD. Although current therapeutic strategies for NAFLD are not effective, we hope that through further research on probucol, we will be able to find suitable treatments to solve this problem in the future.

Efficacy of probucol on cognitive function in Alzheimer's disease: study protocol for a double-blind, placebo-controlled, randomised phase II trial (PIA study)

INTRODUCTION

Preclinical, clinical and epidemiological studies support the hypothesis that aberrant systemic metabolism of amyloid beta (Aβ) in the peripheral circulation is causally related to the development of Alzheimer's disease (AD). Specifically, recent studies suggest that increased plasma concentrations of lipoprotein-Aβ compromise the brain microvasculature, resulting in extravasation and retention of the lipoprotein-Aβ moiety. The latter results in an inflammatory response and neurodegeneration ensues. Probucol, a historic cholesterol-lowering drug, has been shown in murine models to suppress lipoprotein-Aβ secretion, concomitant with maintaining blood-brain-barrier function, suppressing neurovascular inflammation and supporting cognitive function. This protocol details the probucol in Alzheimer's study, a drug intervention trial investigating if probucol has potential to attenuate cognitive decline, delay brain atrophy and reduce cerebral amyloid burden in patients with mild-to-moderate AD.

METHODS AND ANALYSIS

The study is a phase II, randomised, placebo-controlled, double-blind single-site clinical trial held in Perth, Australia. The target sample is 314 participants with mild-to-moderate AD. Participants will be recruited and randomised (1:1) to a 104-week intervention consisting of placebo induction for 2 weeks followed by 102 weeks of probucol (Lorelco) or placebo. The primary outcome is changed in cognitive performance determined via the Alzheimer's Disease Assessment Scales-Cognitive Subscale test between baseline and 104 weeks. Secondary outcomes measures will be the change in brain structure and function, cerebral amyloid load, quality of life, and the safety and tolerability of Lorelco, after a 104week intervention.

ETHICS AND DISSEMINATION

The study has been approved by the Bellberry Limited Human Research Ethics Committee (approval number: HREC2019-11-1063; Version 4, 6 October 2021). Informed consent will be obtained from participants prior to any study procedures being performed. The investigator group will disseminate study findings through peer-reviewed publications, key conferences and local stakeholder events.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12621000726853).

The Combination Treatment of Curcumin and Probucol Protects Chondrocytes from TNF-α Induced Inflammation by Enhancing Autophagy and Reducing Apoptosis via the PI3K-Akt-mTOR Pathway

Osteoarthritis (OA) is a chronic joint disease characterized by cholesterol accumulation in chondrocytes, cartilage degeneration, as well as extracellular matrix (ECM) destruction, and joint dysfunction. Curcumin, a chemical that can reduce cholesterol levels in OA patients, also can inhibit the progression of OA. However, a high concentration of curcumin may also trigger apoptosis in normal chondrocytes. Besides curcumin, probucol that is found can also effectively decrease the cholesterol level in OA patients. Considering that high cholesterol is a risk factor of OA, it is speculated that the combination treatment of curcumin and probucol may be effective in the prevention of OA. To investigate the possible effects of such two chemicals on OA pathophysiology, chondrocyte apoptosis and autophagy behavior under inflammatory cytokine stress were studied, and specifically, the PI3K-Akt-mTOR signaling pathway was studied. Methods. Cell proliferation, colony formation, and EdU assay were performed to identify the cytotoxicity of curcumin and probucol on chondrocytes. Transwell assay was conducted to evaluate chondrocyte migration under TNF-α inflammation stress. Immunofluorescence, JC-1, flow cytometry, RT-PCR, and western blot were used to investigate the signal variations related to autophagy and apoptosis in chondrocytes and cartilage. A histological study was carried out on OA cartilage. Glycosaminoglycan (GAG) release was determined to evaluate the ECM degradation under stress. Results. Compared with a single intervention with curcumin or probucol, a combined treatment of these two chemicals is more effective in terms of protecting chondrocytes from stress injury induced by inflammatory cytokines. The promoted protection may be attributed to the inhibition of apoptosis and the blockage of the autophagy-related PI3K/Akt/mTOR pathway. Such results were also verified in vitro by immunofluorescence staining of OA chondrocytes and in vivo by immunohistochemistry staining of cartilage. Besides, in vivo studies also showed that when applied in combination, curcumin and probucol could block the PI3K-AKT-mTOR signaling pathway; promote COL-II expression; suppress P62, MMP-3, and MMP-13 expression; and inhibit TNF-α-stimulated cartilage degradation. Moreover, the combined medication could help reduce the release of ECM GAGs in OA cartilage and alleviate the severity of OA. Conclusion. A combined treatment of curcumin and probucol could be used to protect chondrocytes from inflammatory cytokine stress via inhibition of the autophagy-related PI3K/Akt/mTOR pathway both in vitro and in vivo, which might be of potential pharmaceutical value for OA prevention and therapy.

Study on the Mechanism of Probucol Nanosuspension on Hyperlipidemic Pancreatitis and Regulation of Blood Lipid Function

High-fat pancreatitis and hyperlipidemia refer to disorders of blood lipid metabolism caused by abnormally elevated blood lipids, and are risk factors for high-risk diseases such as atherosclerosis, coronary heart disease, and cerebral infarction. Hyperlipidemia is also a common disease that is common in modern people, and has a tendency to become younger. In this paper, probucol is made into a self-assembled probucol loaded nanosuspensions (SPN) using molecular selfassembly technology for research on improving its oral absorption. The main research contents include: preparation, prescription screening and characterization of physicochemical properties of SPN nanosuspensions; study of SPN intestinal cell uptake and in vivo dynamic behavior; research on the mechanism of SPN improving oral absorption of probucol and its gastrointestinal Preliminary Evaluation of Physiological Safety. And by using the method of intraperitoneal injection of SPN to interfere with the retrograde bile duct injection of SPN in the hyperlipidemia model, to make hyperlipidemia combined with severe acute pancreatitis to observe the severity of pancreatitis and lung injury; discuss the protective effect of SPN on hyperlipidemia combined with severe acute pancreatitis with lung injury and its mechanism.

Effects of probucol on contrast-induced acute kidney injury in patients undergoing percutaneous coronary intervention

OBJECTIVE

This study was performed to explore the effects of probucol on contrast-induced acute kidney injury (CIAKI) in patients with coronary heart disease undergoing percutaneous coronary intervention (PCI).

METHODS

In total, 220 patients undergoing PCI were randomly assigned to either the control group (hydration from 12 hours before to 12 hours after contrast administration; n = 110) or the probucol group (hydration plus probucol 500 mg twice daily 1 day before and 3 days after the operation; n = 110). The primary endpoint was the occurrence of serum creatinine (Scr)-based CIAKI, defined as an absolute increase in Scr by 0.5 mg/dl (44.2 μmol/L) or a relative 25% increase from baseline within 48 to 72 hours after exposure to contrast medium. The secondary outcomes were composite variations in Scr, blood urea nitrogen (BUN), creatinine clearance rate (Ccr) within 48 to 72 hours, and major adverse events during hospitalization or the 7-day follow-up period after PCI.

RESULTS

The overall incidence of Scr-based CIAKI was 7.3% (16/220): 5.5% (6/110) in the control group and 9.1% (10/110) in the probucol group (χ = 1.078, P = .298). There were no significant differences in the occurrence rate of major adverse events during hospitalization or the 7-day follow-up period after PCI between the groups. Multivariate logistic regression analysis showed that probucol was not an independent protective factor for CIAKI (odds ratio, 1.825; 95% confidence interval, 0.639-5.212; P = .261). However, hydration was an independent protective factor (odds ratio, 0.997; 95% confidence interval, 0.995-0.999; P = .004).

CONCLUSION

Probucol cannot effectively reduce the incidence of CIAKI through its anti-inflammatory and antioxidative stress effects.

Low molecule weight fucoidan mitigates atherosclerosis in ApoE (-/-) mouse model through activating multiple signal pathway

Atherosclerosis (AS) is a chronic inflammatory disease, and many factors are implicated in its progression. This work aims to study the preventive effects and the regulatory mechanism of low-molecular-weight fucoidan (LMWF), which is obtained from Saccharina japonica, on the development of AS. Serum biochemical indices and pathological analyses were determined via ELISA, hematoxylin and eosin (HE) and Oil Red O staining. These results indicated that LMWF ameliorated areas with atherosclerotic lesions and had a significant antioxidant effect. Anticoagulant assays showed that LMWF might serve as a potential anticoagulation drug for inhibiting the formation of atherothrombosis. Double immunofluorescence staining illustrated that LMWF inhibited both SMC proliferation and migration and macrophage formation and differentiation. A molecular biology experiment showed that LMWF exhibited an apparent regulatory effect on various signaling pathways. In conclusion, our results revealed that LMWF mitigated AS in the ApoE (-/-) mouse model by activating multiple signal pathways.

The efficacy of probucol combined with hydration in preventing contrast-induced nephropathy in patients with coronary heart disease undergoing percutaneous coronary intervention: a multicenter, prospective, randomized controlled study

PURPOSE

To investigate the preventive effect of probucol combined with hydration on contrast-induced nephropathy (CIN) in patients with coronary heart disease undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 641 patients undergoing PCI were randomly assigned to either a probucol group (probucol 500 mg twice daily and hydration; n = 321) or a control group (hydration only; n = 320). The primary endpoint was the incidence of CIN, defined as an increase in serum creatinine (Scr) by ≥ 44.2 μmol/L or ≥ 25% within 72 h after the administration of contrast agent. Secondary endpoints were changes in Scr, cystatin-C (Cys-C), creatinine clearance rate (Ccr), C-reactive protein (CRP), superoxide dismutase (SOD), and glutathione (GSH) within 72 h, and major adverse events during hospitalization or the 14-day follow-up period.

RESULTS

The incidence of CIN was 4.0% (13/321) in the probucol group and 10.9% (35/320) in the control group. The probucol group had lower Cys-C and higher Ccr at 48 and 72 h after PCI compared with the control group. At 48 and 72 h following the operation, Cys-C and CRP were lower in the probucol group compared with the control group, but Ccr, SOD, and GSH were higher. There were no differences in the incidence of major adverse events during hospitalization or the 14-day follow-up between the groups. Multivariate logistic regression analysis showed that probucol was an independent protective factor for CIN.

CONCLUSIONS

Probucol combined with hydration more effectively decreased the incidence of CIN in patients with coronary heart disease undergoing PCI compared with hydration alone.

Telmisartan combined with probucol effectively reduces urinary protein in patients with type 2 diabetes: A randomized double-blind placebo-controlled multicenter clinical study

BACKGROUND

Persistent proteinuria is an important factor contributing to the progression of diabetic nephropathy. The present randomized double-blind placebo-controlled multicenter clinical study evaluated the efficacy and safety of telmisartan combined with the antioxidant probucol in reducing urinary protein levels in patients with type 2 diabetes (T2D).

METHODS

Patients with T2D and 24-h proteinuria 0.5-3 g were enrolled in the study and randomly assigned to one of two groups: a telmisartan or a probucol + telmisartan group. Both groups were given telmisartan 80 mg q.d. for 48 weeks. The probucol + telmisartan group was given probucol 500 mg b.i.d. for the first 24 weeks, with the dosage then reduced to 250 mg b.i.d. for the remaining 24 weeks. The telmisartan group was given probucol placebo.

RESULTS

In all, 160 patients were enrolled in the present study. The 24-h proteinuria levels were significantly reduced in the probucol + telmisartan compared with telmisartan group. For patients with baseline 24-h proteinuria levels <1.0 g, both treatments resulted in significant reductions in 24-h proteinuria levels after 48 weeks treatment. However, in patients with baseline 24-h proteinuria levels ≥1.0 g, 24-h proteinuria levels after 48 weeks treatment were only reduced in the probucol + telmisartan group. There was no significant difference between the two groups for either adverse cardiovascular or other events.

CONCLUSIONS

In patients with diabetic nephropathy, probucol combined with telmisartan more effectively reduces urinary protein levels than telmisartan alone.

Rationale and Design of the PROSPECTIVE Trial: Probucol Trial for Secondary Prevention of Atherosclerotic Events in Patients with Prior Coronary Heart Disease

BACKGROUND

Reduction of serum LDL-cholesterol by statins was shown to improve clinical outcomes in patients with coronary heart disease (CHD). Although intensive statin therapy significantly reduced cardiovascular risks, atherosclerotic cardiovascular events have not been completely prevented. Therefore, effective pharmacologic therapy is necessary to improve "residual risks" in combination with statins. Probucol has a potent antioxidative effect, inhibits the oxidation of LDL, and reduces xanthomas. Probucol Trial for Secondary Prevention of Atherosclerotic Events in Patients with Prior Coronary Heart Disease (PROSPECTIVE) is a multicenter, randomized, prospective study designed to test the hypothesis that the addition of probucol to other lipid-lowering drugs will prevent cerebro- and cardiovascular events in patients with prior coronary events and high LDL cholesterol levels.

STUDY DESIGN

The study will recruit approximately 860 patients with a prior CHD and dyslipidemia with LDL-C level ≥140 mg/dl without any medication and those treated with any lipid-lowering drugs with LDL-C level ≥100 mg/dl. Lipid-lowering agents are continuously administered during the study period in control group, and probucol (500 mg/day, 250 mg twice daily) is added to lipid-lowering therapy in the test group. The efficacy and safety of probucol with regard to the prevention of cerebro- and cardiovascular events and the intima-media thickness of carotid arteries as a surrogate marker will be evaluated.

SUMMARY

PROSPECTIVE will determine whether the addition of probucol to other lipid-lowering drugs improves cerebro- and cardiovascular outcomes in patients with prior coronary heart disease. Furthermore, the safety of a long-term treatment with probucol will be clarified.

Nanoassembly of probucol enables novel therapeutic efficacy in the suppression of lung metastasis of breast cancer

Metastasis is one of the major obstacles hindering the success of cancer therapy. The directed nanoassembly of probucol results in the "DNP" system, which greatly improves the oral delivery of probucol and subsequently leads to a novel therapeutic efficacy of probucol in the suppression of lung metastasis of breast cancer. DNP is formed by employing the intermolecular hydrophobic interactions between probucol and polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (also known as Triton X-100). After oral administration, the probucol concentration in the intestines is surprisingly about 200 times higher if it is applied as DNP rather than free probucol; it can be absorbed into intestinal enterocytes via clathrin-mediated endocytosis and transported into the systemic circulation through the lymphatic pathway. Moreover, the oral bioavailability of probucol is significantly higher-13.55 times higher-when applied as DNP in place of free probucol. The drug concentration in major organs is also significantly increased. The in vitro measurements show that the migration and invasion abilities of 4T1 cells are obviously inhibited by DNP. In particular, in an orthotopic metastatic breast cancer model, the notable suppression of lung metastasis from DNP is observed, but no effect is seen from the free-probucol suspension. As a result, the directed drug nanoassembly may open a new route for enhancing oral drug delivery and enable new therapeutic abilities for probucol against cancer metastasis.

Probucol inhibited Nox2 expression and attenuated podocyte injury in type 2 diabetic nephropathy of db/db mice

The present study was conducted to investigate the effects of probucol on the progression of diabetic nephropathy and the underlying mechanism in type 2 diabetic db/db mice. Eight weeks db/db mice were treated with regular diet or probucol-containing diet (1%) for 12 weeks. Non-diabetic db/m mice were used as controls. We examined body weight, blood glucose, and urinary albumin. At 20 weeks, experimental mice were sacrificed and their blood and kidneys were extracted for the analysis of blood chemistry, kidney histology, oxidative stress marker, and podocyte marker. As a result, 24 h urinary albumin excretions were reduced after probucol treatment. There were improvements of extracellular matrix accumulation and fibronectin and collagen IV deposition in glomeruli in the probucol-treated db/db mice. The reduction of nephrin and the loss of podocytes were effectively prevented by probucol in db/db mice. Furthermore, probucol significantly decreased the production of thiobarbituric acid-reactive substances (TBARS), an index of reactive oxygen species (ROS) generation and down-regulated the expression of Nox2. Taken together, our findings support that probucol may have the potential to protect against type 2 diabetic nephropathy via amelioration of podocyte injury and reduction of oxidative stress.

Vascular protectants for the treatment of atherosclerosis

AGI-1067, the monosuccinic acid ester of probucol, is a phenolic antioxidant member of a novel class of agents termed vascular protectants. It has strong antioxidant properties, equipotent to those of probucol, and anti-inflammatory properties. It inhibits gene expression of vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 and has been effective at preventing atherosclerosis in all tested animal models. It also improved luminal dimensions of reference segments in the percutaneous coronary intervention (PCI) vessels in the CART-1 clinical trial, which suggests a direct anti-atherosclerosis effect. Two important trials that test the antioxidant/anti-inflammatory hypothesis are ongoing with AGI-1067: the Canadian Atherosclerosis and Restenosis Trial, which assesses its value for the reduction of both atherosclerosis progression in non-PCI vessels and post-PCI restenosis, and the Aggressive Reduction of Inflammation Stops Events trial, which is evaluating the effects of AGI-1067 on hard cardiovascular outcomes.

AGI-1067, a novel vascular protectant, anti-inflammatory drug and mild antiplatelet agent for treatment of atherosclerosis

Oxidation-sensitive signals play an important role in platelet activation. AGI-1067 is a novel, phenolic, intra- and extracellular antioxidant that inhibits the expression of a number of proinflammatory genes involved in atherosclerosis. AGI-1067 is the metabolically stable monosuccinic acid ester of probucol, and a potent phenolic antioxidant representing a novel class of orally bioavailable compounds termed vascular protectants. AGI-1067 exhibits antioxidant activity equipotent to probucol. In addition, animal studies have demonstrated dual pharmacological activities of AGI-1067: the ability to block the expression of oxidation-sensitive inflammatory genes including genes that code for vascular cell adhesion molecule-1 and monocyte chemotactic protein-1. Importantly, AGI-1067 also exhibits mild antiplatelet properties inhibiting surface expression of various key platelet receptors, the formation of platelet monocyte microparticles and PAR-1 thrombin receptors. AGI-1067 is currently being tested in the late trials, and if proven to improve clinical outcomes (ARISE trial), the drug will ultimately be used in patients with different manifestations of atherosclerosis and atherothrombosis.

Combined therapeutic effect of probucol and cilostazol on endothelial function in patients with silent cerebral lacunar infarcts and hypercholesterolemia: a preliminary study

OBJECTIVE

This study evaluated the efficacy of combined therapy with probucol and cilostazol on endothelial function in silent lacunar cerebral infarcts (SLCI) and mild hypercholesterolemia.

SUBJECTS AND METHODS

Flow-mediated vasodilatation (FMD) and nitroglycerin-induced vasodilatation (NMD) were measured before and after 4 weeks of combined therapy with probucol (500 mg/day) and cilostazol (200 mg/day) in 34 patients with a mean age of 72 ± 7 years (range 57-80 years) with SLCI, mild hypercholesterolemia (low-density lipoprotein cholesterol >100 mg/dl) and impaired endothelial function (FMD <6%). Patients were randomly allocated to one of the following two treatment groups: (1) aspirin (100 mg/day) with behavioral modifications, such as diet and/or exercise therapy (A group or control group, n = 17), and (2) probucol and cilostazol treatment (PC group, n = 17), also with behavioral modifications.

RESULTS

Although the baseline FMD was not different between the two treatment arms (2.7 ± 1.5 vs. 2.6 ± 1.5%, n.s.), the posttreatment FMD was significantly improved in the PC group (from 2.7 ± 1.5 to 3.5 ± 1.7%, p < 0.05) but not in the A group (from 2.6 ± 1.5 to 2.9 ± 1.4%, n.s.). No differences were observed between baseline and posttreatment NMD in either group. The effects of treatments on lipid profiles were more profound in the PC group.

CONCLUSION

Combined treatment with probucol and cilostazol resulted in subacute improvement in FMD/endothelial function in patients with SLCI with mild hypercholesterolemia. This combination therapy has the potential to reduce the risk of cardiovascular events via improvements in endothelial function and lipid profiles.

Probucol increases striatal glutathione peroxidase activity and protects against 3-nitropropionic acid-induced pro-oxidative damage in rats

Huntington's disease (HD) is an autosomal dominantly inherited neurodegenerative disease characterized by symptoms attributable to the death of striatal and cortical neurons. The molecular mechanisms mediating neuronal death in HD involve oxidative stress and mitochondrial dysfunction. Administration of 3-nitropropionic acid (3-NP), an irreversible inhibitor of the mitochondrial enzyme succinate dehydrogenase, in rodents has been proposed as a useful experimental model of HD. This study evaluated the effects of probucol, a lipid-lowering agent with anti-inflammatory and antioxidant properties, on the biochemical parameters related to oxidative stress, as well as on the behavioral parameters related to motor function in an in vivo HD model based on 3-NP intoxication in rats. Animals were treated with 3.5 mg/kg of probucol in drinking water daily for 2 months and, subsequently, received 3-NP (25 mg/kg i.p.) once a day for 6 days. At the end of the treatments, 3-NP-treated animals showed a significant decrease in body weight, which corresponded with impairment on motor ability, inhibition of mitochondrial complex II activity and oxidative stress in the striatum. Probucol, which did not rescue complex II inhibition, protected against behavioral and striatal biochemical changes induced by 3-NP, attenuating 3-NP-induced motor impairments and striatal oxidative stress. Importantly, probucol was able to increase activity of glutathione peroxidase (GPx), an enzyme important in mediating the detoxification of peroxides in the central nervous system. The major finding of this study was that probucol protected against 3-NP-induced behavioral and striatal biochemical changes without affecting 3-NP-induced mitochondrial complex II inhibition, indicating that long-term probucol treatment resulted in an increased resistance against neurotoxic events (i.e., increased oxidative damage) secondary to mitochondrial dysfunction. These data appeared to be of great relevance when extrapolated to human neurodegenerative processes involving mitochondrial dysfunction and indicates that GPx is an important molecular target involved in the beneficial effects of probucol.

[Impact of adding folic acid, vitamin B(12) and probucol to standard antihypertensive medication on plasma homocysteine and asymmetric dimethylarginine levels of essential hypertension patients]

OBJECTIVE

To investigate the impact of adding folic acid, vitamin B(12) and probucol to standard antihypertensive medication on plasma homocysteine (Hcy) and asymmetric dimethylarginine (ADMA), serum NO and eNOS of essential hypertensive patients.

METHOD

A total of 120 patients with hypertension were randomly divided to three groups (n = 40 each): group 1 (standard medication), group 2 (adding folic acid 5 mg/day and vitamin B(12) 500 µg twice daily) and group 3 (adding folic acid 5 mg/day and vitamin B(12) 500 µg twice daily and probucol 500 mg twice daily). Plasma Hcy and ADMA, serum NO and eNOS levels were observed at baseline, 2 and 12 weeks after various therapy.

RESULTS

In group 1, concentrations of plasma Hcy [(23.06 ± 14.15) µmol/L, (23.67 ± 12.31) µmol/L, (23.25 ± 11.64) µmol/L], ADMA [(0.21 ± 0.12) µmol/L, (0.23 ± 0.13) µmol/L, (0.21 ± 0.09) µmol/L] and serum NO [(64.14 ± 15.07) µmol/L, (65.29 ± 15.04) µmol/L, (65.32 ± 13.58) µmol/L], eNOS [(20.02 ± 4.50) µg/L, (20.79 ± 4.03) µg/L, (19.82 ± 5.70) µg/L] remained unchanged during the 12 weeks therapy (all P > 0.05). In group 2, concentrations of plasma Hcy [(12.54 ± 6.49) µmol/L] and ADMA[(0.18 ± 0.07) µmol/L] were significantly decreased after the treatment of 12 weeks than the treatment baseline value [(21.51 ± 7.82) µmol/L, (0.20 ± 0.12) µmol/L] and 2 weeks value[(19.38 ± 8.14) µmol/L, (0.21 ± 0.12) µmol/L], however the concentrations of serum NO and eNOS showed contrary results of the Hcy and ADMA's. (all P < 0.05). In group 3, similar changes occurred at 2 weeks after therapy (P < 0.05 2 weeks vs. baseline and 12 weeks vs. 2 weeks). Plasma ADMA level was positively correlated with Hcy at baseline (r = 0.546, P < 0.05).

CONCLUSIONS

Supplementation of folic acid, VitB(12) and/or probucol helps to improve endothelial function and reduce plasma Hcy and ADMA levels in patients with hypertension.

Combined effect of atorvastatin and probucol on plasma cystatin C levels and severity of coronary lesion in patients with borderline coronary lesion

BACKGROUND

The plasma cystatin C concentration (PcyC) has been demonstrated to have prognostic value in acute coronary syndrome, but the study of PcyC in patients with borderline coronary lesions is limited. Moreover, the effects of atorvastatin and probucol on PcyC and the severity of coronary lesions are unknown. This study was to evaluate the effects of the combination of atorvastatin and probucol on PcyC and severity of coronary lesion in patients with borderline coronary lesions.

METHODS

One hundred and thirty consecutive patients with borderline coronary lesions (40% to 60% isolated single stenosis assessed by quantitative coronary angiography) were enrolled into the borderline coronary lesion (BCL) group, and one hundred and thirty-six subjects without coronary lesions comprised the controls (CTR). The subjects in the BCL group were randomized into routine treatment (RTT, n = 60), and combined treatment with atorvastatin 20 mg plus probucol 1.0 g daily added to routine medication (CBT, n = 70), both groups were treated for 6 months continuously. The levels of PcyC, high-sensitive C-reactive protein (hs-CRP), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) were determined. One hundred and four subjects in the BCL group were rechecked by coronary angiography.

RESULTS

PcyC levels were significantly higher in the BCL group than in the CTR group; (2003.26 ± 825.73) ng/ml vs. (1897.83 ± 664.46) ng/ml (P < 0.01). Compared with patients in the RTT group, the levels of PcyC, TC, LDL-C, TG and hs-CRP were significantly lower in the CBT group (P < 0.05). Moreover, there was a trend towards a slight decrease in the RTT patients, (54.38 ± 10.67)% vs. (50.29 ± 9.89)% (P > 0.05), and a significant decrease in the CBT patients, (53.65 ± 9.48%) vs. (40.38 ± 12.93)% (P < 0.05), in the mean percent stenosis of borderline coronary lesions before and after six months of treatment.

CONCLUSIONS

Cystatin C played an important role in the development of coronary artery disease, and was associated with the severity of coronary lesions. The combination of atorvastatin and probucol decreased PcyC levels, and could be the treatment of choice.

[Effects of three different treatments on atherosclerosis and adipose in rats]

OBJECTIVE

To explore the effects of three different treatments, including probucol plus aspirin (PS), lovastatin plus aspirin (AS) and probucol, lovastatin plus aspirin (PAS) on atherosclerotic plaque and adipose.

METHODS

A total of 31 SD rats with established atherosclerosis were randomly divided into control group (n = 7), high-fat group (n = 4), PS group (n = 8), AS group (n = 5) and PAS group (n = 7). The PS group rats were lavaged with probucol (104.4 mg×kg(-1)×d(-1)) and aspirin 10.4 mg×kg(-1)×d(-1)), AS group ones aspirin (10.4 mg×kg(-1)×d(-1)) and lovastatin (2.1 mg×kg(-1)×d(-1)) and PAS group ones probucol (104.4 mg×kg(-1)×d(-1)), aspirin (10.4 mg×kg(-1)×d(-1)) and lovastatin (2.1 mg×kg(-1)×d(-1)) for 8 weeks. At the same time, the control group received an equal volume of saline. Finally the plaque stability and adipose function of treatment groups were evaluated by the changes of body weight, serum parameters, adipose weights and pathological specimens.

RESULTS

Body weights in PS and PAS groups significantly increased than those in AS group (251 g ± 5 g and 247 g ± 7 g vs 220 g ± 6 g, P < 0.01). The serum levels of low density lipoprotein cholesterol (LDL), glucose (Glu), total cholesterol (TC) and high density lipoprotein cholesterol (HDL) were significantly better in PS and PAS groups than those in AS group (P < 0.01). The level of tumor necrosis factor-alpha (TNF-α) was lower in PAS group than that in high-fat group (27 ± 21 vs 100 ± 34 pg/ml, P < 0.05). The stability level of atherosclerotic plaque was more in PAS group than those in PS and AS groups by oil red staining in aorta, oil red staining in different organs and hematoxylin and eosin staining in different aortal parts.

CONCLUSION

Atherosclerosis improves more pronouncedly in PS and PAS groups than that in AS group. Through an analysis of the changes of fat-related indicators, adipose factor may play an important role in atherosclerotic treatment.

[Effect of probucol on serum malondialdehyde and superoxide dismutase in patients with primary hypertension]

OBJECTIVE

To observe the therapeutic effect of probucol on serum malondialdehyde (MDA) and superoxide dismutase (SOD) in patients with primary hypertension.

METHODS

A randomized study was performed on 40 patients with hypertension. The patients were randomly assigned to the control (levamlodipine besylate 2.5 mg/d plus benazepril 10 mg/d, n=20) or probucol group (levamlodipine besylate 2.5 mg/d plus benazepril 10 mg/d plus probucol 500 mg/d, n=20). An additional twenty healthy people were enrolled in the study (normal group). All subjects were followed up for a period of four weeks. Lipids and hepatic/renal function were measured at baseline and after 4 weeks. The levels of serum MDA and SOD activity were assayed by chemical colorimetry, and other indices, including blood pressure, lipids and hepatic/renal function, were measured at baseline and after 4 weeks.

RESULTS

Compared to the normal group, the levels of MDA in all of the hypertension patient groups were higher, SOD was lower. The antihypertensive treatment decreased serum MDA levels but increased SOD content, and probucol treatment exaggerated these effects, with greater reduction of serum MDA levels and greater increase of SOD content.

CONCLUSION

The treatment with probucol can improve oxidative stress in hypertension patients, resulting in reduced serum MDA levels and improved SOD activity, thus contributing agreater antihypertensive effect.

[Efficacy observation of combination of Lumbrukinase Capsule and Probucol Tablet in treating cerebral infarction patients' unstable atheromatous plaque of the carotid artery]

OBJECTIVE

To observe the effects of combination of Lumbrukinase Capsule (LC) and Probucol Tablet (PT) in treating cerebral infarction (CI) patients' unstable atheromatous plaque of the carotid artery.

METHODS

150 patients were randomly assigned to the PT group and the LC group, 75 cases in each. Patients in the PT group took 0.5 g PT each time, twice daily. On the basis of PT, patients in the LC group also took 600 thousand U LC, thrice daily. The treatment course was 12 months for all. The serum levels of TC, TG, HDL-C, LDL-C, fibrinogen (FIB), and changes of the carotid atherosclerotic plaque were measured before treatment, 6 and 12 months after treatment. Meanwhile, adverse events were recorded.

RESULTS

The serum levels of TC, TG, and LDL-C were all lower 6 months after treatment than before treatment in the two groups, showing statistical significance (P < 0.05). The serum level of HDL-C was higher 6 months after treatment than before treatment in the two groups, showing no statistical significance (P > 0.05). When compared with before treatment in the same group, the serum level of FIB significantly decreased after treatment. Besides, there was statistical difference between the two groups (P < 0.05). There was no statistical difference in the serum levels of blood lipids or FIB between 12-month treatment and 6-month treatment in the same group (P > 0.05). The plaque effective rate in the LC group was superior to that of the PT group, showing statistical significance (P < 0.01). During the treatment period, the occurrence of cerebrovascular event was lower in the LC group than in the PT group (P < 0.05). Partial patients in the two groups had gastric discomfort.

CONCLUSIONS

The combination of LC and PT could prevent and treat arteriosclerosis, stabilize the plaque, effectively lower the occurrence of ischemic events. Its clinical application did not increase the risk of hemorrhage. It was safe and effective, worthy of spreading. It was necessary to further observe whether combination of LC and PT could increase side effects of the digestive tract.

[Novel therapy for atherosclerosis and inflammatory vascular disease]

How to manage residual atherosclerosis risk after the statin therapy is a major concern in cardiovascular medicine. In addition to life-style modifications, new drugs against atherosclerotic and inflammatory vascular diseases are expected. In current clinical trials, phospholipase A2 inhibitors(darapladib, varespladib), RVX-208, D-4F, CETP inhibitors (anacetrapib, dalcetrapib), succinobucol are investigated. Some has been failed, but others are still promising. On molecular target basis of PAF-AH, CETP, PON, ABC transporters of A1 and G1, SR-BI, HO-1, potential benefits and side effects are discussed.

Probucol attenuates cyclophosphamide-induced oxidative apoptosis, p53 and Bax signal expression in rat cardiac tissues

Cyclophosphamide (CP) is a widely used in cancer chemotherapy and immunosuppression, which could cause toxicity of the normal cells due to its toxic metabolites. Probucol, cholesterol-lowering drug, acts as potential inhibitor of DNA damage and shows to protect against doxorubicin-induced cardiomyopathy by enhancing the endogenous antioxidant system including glutathione peroxidase, catalase and superoxide dismutase. This study examined the possible protective effects of probucol, a lipid-lowering compound with strong antioxidant properties, against CP-induced cardiotoxicity. This objective could be achieved through studying the gene expression-based on the possible protective effects of probucol against CP-induced cardiac failure in rats. Adult male Wistar albino rats were assigned into 4 treatment groups: Animals in the first (control) and second (probucol) groups were injected intraperitoneally with corn oil and probucol (61 mg/kg/day), respectively, for two weeks. Animals in the third (CP) and fourth (probucol plus CP) groups were injected with the same doses of corn oil and probucol (61 mg/kg/day), respectively, for one week before and one week after a single dose of CP (200 mg/kg, I.P.). The p53, Bax, Bcl2 and oxidative genes signal expression were measured by real time PCR. CP-induced cardiotoxicity was clearly observed by a significant increase in serum creatine phosphokinase isoenzyme (CK-MB) (117%), lactate dehydrogenase (LDH) (64%), free (69%) and esterified cholesterol (42%) and triglyceride (69%) compared to control group. In cardiac tissues, CP significantly increases the mRNA expression levels of apoptotic genes, p53 with 2 folds and Bax with 1.6 fold, and decreases the anti-apoptotic gene Bcl2 with 0.5 fold. Moreover, CP caused down-regulation of antioxidant genes, glutathione peroxidase, catalase, and superoxide dismutase and increased the lipid peroxidation and decreased adenosine triphosphate (ATP) (40%) and ATP/ADP (44%) in cardiac tissues. Probucol pretreatment not only counteracted significantly the CP-induced increase in cardiac enzymes and apoptosis but also it induced a significant increase in mRNA expression of antioxidant enzymes and improved ATP, ATP/ADP, glutathione (GSH) in cardiac tissues. In conclusion, data from the present study suggest that probucol prevents the development of CP-induced cardiotoxicity by a mechanism related, at least in part, to its ability to increase mRNA expression of antioxidant genes and to decrease apoptosis in cardiac tissues with the consequent improvement in mitochondrial oxidative phosphorylation and energy production.

High-density lipoprotein therapeutics and cardiovascular prevention

The field of cardiovascular prevention has long anticipated the evolution of high-density lipoprotein (HDL) therapy from unproven metabolic tweaking to pillar of risk reduction on par with low-density lipoprotein control. However, the convincing epidemiologic data linking HDL cholesterol (HDL-C) and cardiovascular disease risk in an inverse correlation has not yet translated into clinical trial evidence supporting linearity between HDL-C increases and risk reduction, or identifying obvious goals of therapy. Although HDL-C-increasing lifestyle maneuvers and established HDL drugs such as niacin and fibrates are likely to protect the vasculature, the negative results obtained in trials of a cholesteryl ester transfer protein inhibitor remind us that HDL-C increases are not always beneficial. It is becoming clear that a functional HDL is a more desirable target than simply increasing HDL-C levels. The larger objective of improving HDL functionality (with or without HDL-C level changes) is bound to become the guiding principle for pharmaceutical research in this area. Several new compounds currently being tested bridge the classical aim of increasing HDL-C levels with the novel target of improving HDL function.

Cross-platform expression microarray performance in a mouse model of mitochondrial disease therapy

Microarray expression profiling has become a valuable tool in the evaluation of the genetic consequences of metabolic disease. Although 3'-biased gene expression microarray platforms were the first generation to have widespread availability, newer platforms are gradually emerging that have more up-to-date content and/or higher cost efficiency. Deciphering the relative strengths and weaknesses of these various platforms for metabolic pathway-level analyses can be daunting. We sought to determine the practical strengths and weaknesses of four leading commercially available expression array platforms relative to biologic investigations, as well as assess the feasibility of cross-platform data integration for purposes of biochemical pathway analyses.

METHODS

Liver RNA from B6.Alb/cre,Pdss2(loxP/loxP) mice having primary coenzyme Q deficiency was extracted either at baseline or following treatment with an antioxidant/antihyperlipidemic agent, probucol. Target RNA samples were prepared and hybridized to Affymetrix 430 2.0, Affymetrix Gene 1.0 ST, Affymetrix Exon 1.0 ST, and Illumina Mouse WG-6 expression arrays. Probes on all platforms were re-mapped to coding sequences in the current version of the mouse genome. Data processing and statistical analysis were performed by R/Bioconductor functions, and pathway analyses were carried out by KEGG Atlas and GSEA.

RESULTS

Expression measurements were generally consistent across platforms. However, intensive probe-level comparison suggested that differences in probe locations were a major source of inter-platform variance. In addition, genes expressed at low or intermediate levels had lower inter-platform reproducibility than highly expressed genes. All platforms showed similar patterns of differential expression between sample groups, with 'steroid biosynthesis' consistently identified as the most down-regulated metabolic pathway by probucol treatment.

CONCLUSIONS

This work offers a timely guide for metabolic disease investigators to enable informed end-user decisions regarding choice of expression microarray platform best-suited to specific research project goals. Successful cross-platform integration of biochemical pathway expression data is also demonstrated, especially for well-annotated and highly expressed genes. However, integration of gene-level expression data is limited by individual platform probe design and the expression level of target genes. Cross-platform analyses of biochemical pathway data will require additional data processing and novel computational bioinformatics tools to address unique statistical challenges.

[Effects of atorvastatin, alone and in combination with probucol on endothelial function in patients with acute coronary syndrome]

OBJECTIVES

To evaluate the effects of combined atorvastatin and probucol use on endothelial function in patients with acute coronary syndrome (ACS).

METHODS

Thirty patients with ACS were randomized to receive atorvastatin (20 mg/d) and probucol (500 mg/d, combination group, n = 15) or atorvastatin (20 mg/d) alone (atorvastatin group) within 24 h after admission for 4 weeks. Endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent sublingual nitroglycerin-mediated dilatation (NMD) as well as the levels of lipids and C-reactive protein were assessed at baseline, 1 week and 4 weeks after therapy.

RESULTS

Compared to baseline, the levels of total cholesterol, LDL-C and C-reactive protein were significantly reduced after 1 week and 4 weeks in both groups, FMD equally increased after 1 week in both groups (atorvastatin group: 3.75% +/- 0.78% vs. 1.09% +/- 0.44%, combination group: 3.67% +/- 0.36% vs. 1.24% +/- 0.37%, P < 0.01). Post 4 weeks therapy, FMD increase was significantly higher in combination group (3.67% +/- 0.36% at 1 week vs. 6.85% +/- 0.64% at 4 weeks, P < 0.01) than that in atorvastatin group (3.75% +/- 0.78% vs. 3.80% +/- 0.31%, P = 0.954). NMD also equally and increased over 4 weeks in two groups (P < 0.01 vs. baseline). There was no correlation between the change in FMD/NMD and the changes in lipids or C-reactive protein levels.

CONCLUSIONS

The combined atorvastatin and probucol therapy early after ACS is superior to atorvastatin alone on improving endothelial function.

[Effects of probucol, aspirin and atorvastatin combination therapy upon atherosclerosis]

OBJECTIVE

To investigate the effects of probucol, aspirin and atorvastatin (PAS) combination therapy upon atherosclerosis.

METHODS

A total of 436 patients with coronary artery disease were selected and randomly divided into control group (aspirin 100 mg, atorvastatin 10 mg daily) and PAS group (aspirin 100 mg, atorvastatin 10 mg and probucol 0.25 g daily). After a 1-year treatment course, 378 cases remained in the study (201 in control group vs. 177 in PAS group). These patients were followed for throughout the study course and their serum levels of high density lipoprotein (HDL), ox-LDL, TXB2 and MMP-9 were measured at 6 and 12 months respectively. Twenty cases were diagnosed with carotid artery plaque by carotid ultrasound and 16 cases remained in the PAS group. They were followed with ultrasound for plaque thickness.

RESULTS

In the control group, the pre-treatment level of MMPs and ox-LDL were not statistically different from the post-treatment level (P > 0.05). In the PAS group, the pre-treatment level of ox-LDL was (23.46 +/- 0.01) mmol/L and the post-treatment level (16.13 +/- 0.02) mmol/L. There was a decrease of 31.7% (P < 0.05). The pre-treatment level of MMPs and MMP-9 in the control group was not statistically different from the post-treatment level. The pre-treatment level of MMP-9 in the PAS group was (7.15 +/- 0.01) mmol/L and the post-treatment level (4.19 +/- 0.02) mmol/L. There was a decrease of 42.4% (P < 0.05). During the course of follow-up, the hospitalization rate, angina recurrence rate, myocardial infarction rate and mortality rate for the control group were 23 (11.4%), 28 (13.9%), 4 (2.0%) and 2 (1.0%) respectively. In the PAS group, the corresponding values were 6 (3.4%), 13 (7.3%), 1 (0.6%) and 0 respectively. All parameters of adverse events showed a significant decrease in the PAS group (P < 0.05). Among the cases with carotid plaque, the pretreatment measurements of intima thickness and plaque thickness were (0.103 +/- 0.002) cm and (0.248 +/- 0.001) cm while the post-treatment corresponding measurements (0.097 +/- 0.001) cm and (0.209 +/- 0.002) cm respectively. There was a significant difference between the PAS group and the control group (P < 0.05).

CONCLUSION

Antioxidant probucol significantly inhibits the generation of ox-LDL and MMP-9. PAS therapy also reduces the plaque thickness and decreases the rate of adverse event in patients with atherosclerosis. Antioxidants can be considered as a new adjunct therapy in the treatment of atherosclerosis.

Probucol prevents the progression of fatty liver in MSG obese mice

We investigated the effect of Probucol in preventing fatty liver in monosodium-L-glutamate (MSG) treated obese mice and control mice fed a high fat diet. MSG mice became significantly obese 9 weeks after birth with higher levels of serum blood glucose, total cholesterol, HDL-cholesterol, GPT, and cholinesterase, and had greater triglyceride contents in their livers relative to control mice. Morphologically, MSG obese mice also had a marked fatty liver. Administration of Probucol mixed with the high fat diet for 2 weeks significantly decreased the serum levels of total cholesterol and HDL-cholesterol, and liver triglyceride contents in both MSG and control mice. Morphologically, the livers were less fatty after Probucol treatment. These results suggest that Probucol prevents the development of fatty liver, and in addition reduces hypercholesterolemia.

Pretreatment with probucol attenuates cardiomyocyte apoptosis in a rabbit model of ischemia/reperfusion

OBJECTIVE

Apoptosis plays an important role in ischemic reperfusion injury. Probucol is a hypolipidemic agent and has antioxidant activity, which may inhibit the oxidative modification of low-density lipoprotein cholesterol. Studies have demonstrated that probucol improves left ventricular function, prevents left ventricular dilatation, and reduces cardiac fibrosis. However, the exact mechanism of probucol on the cardioprotective effect is not known. The objective of the present study was to examine the effect of probucol on ischemia/reperfusion-induced cardiomyocyte apoptosis.

MATERIAL AND METHODS

Thirty male New Zealand White rabbits were randomly divided into sham, control, and treated groups, each group comprising 10 rabbits. Before establishment of the ischemia/reperfusion model, animals in the treated group were additionally fed daily with probucol (1000 mg per day) for 4 weeks. In the sham group, the heart was exposed after the chest had been opened, but the coronary artery was not ligated. The animals were killed 150 min after the procedure. In the other two groups, the rabbits were subjected to 30-min of coronary occlusion followed by a 2-h reperfusion. A blood sample was drawn from the right atrium before the animal was killed. The apoptotic myocytes were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Expression of caspase-3 and mitochondrial cytochrome c release was detected by immunohistochemical analysis and Western blot analysis. The level of serum superoxide dismutase (SOD) was tested using the xanthine oxidase method, and the content of serum malondialdehyde (MDA) was measured by colorimetry.

RESULTS

As compared with the sham group, the control group had a significantly higher apoptotic index ((32.48 +/- 4.56) % versus (0.56 +/- 0.18) %, p < 0.01) and serum MDA concentration (2.70 +/- 0.64 versus 1.06 +/- 0.46 micromol/L, p < 0.01), and a significantly lower serum SOD level (144.27 +/- 21.69 versus 204.64 +/- 16.67 microU/L, p < 0.01). Probucol pretreatment apparently caused a decrease in the apoptotic index ((21.64 +/- 3.08) %, p < 0.01 versus the sham or control group) and serum MDA concentration (1.95 +/- 0.51 micromol/L, p < 0.01 versus the sham or control group), and increased the levels of serum SOD (162.61 +/- 16.13 microU/L, p < 0.01 versus the sham group; p < 0.05 versus the control group). The caspase-3 activation and mitochondrial cytochrome c release in the control group were also higher than those in the treated group (p < 0.01).

CONCLUSIONS

The present study shows that probucol attenuates ischemia/reperfusion-induced cardiomyocyte apoptosis. The protective effect of probucol on the myocardium may be partly due to its antioxidant activity.

Molecular mechanisms underlying the antiatherosclerotic and antidiabetic effects of probucol, succinobucol, and other probucol analogues

PURPOSE OF REVIEW

New therapies for the management of cardiovascular disease remain highly desirable, yet the recently developed agents, such as the cholesterylester transfer protein inhibitor torcetrapib, the antidiabetic agent rosiglitazone, and anti-inflammatory inhibitors of cyclooxygenase-2, have failed. In this review, the more recent developments in the molecular mechanisms underlying the beneficial activities of probucol and related compounds are described.

RECENT FINDINGS

In-vivo and in-vitro studies have revealed that several of the protective activities of probucol can be explained by the ability of this drug to induce the enzyme heme oxygenase-1. It is now apparent that the sulfur atoms, rather than the phenol moieties of probucol, are required for its antiatherogenic and antirestenotic activities. Compounds related to probucol that have improved efficacy without the adverse effects offer promise as novel therapies of cardiovascular disease. Recent results suggest these compounds may also be used for the prevention of type-2 diabetes, a disease that is increasing in prevalence and importance worldwide.

SUMMARY

The development of derivatives of probucol targeting anti-inflammatory and antioxidant processes, perhaps via induction of heme oxygenase-1, may add to the armamentarium of current agents used in treatment of atherosclerotic disease and diabetes.

[Role of probucol in preventing contrast induced acute kidney injury after coronary interventional procedure: a randomized trial]

OBJECTIVE

Contrast induced acute kidney injury (CIAKI) is a significant clinical problem. We, therefore, performed a prospective, randomized trial to investigate the role of probucol in the prevention of CIAKI in patients with unstable angina pectoris (UAP) undergoing percutaneous coronary angiography (CAG) and interventions (PCI).

METHODS

We studied 205 patients with UAP, who underwent CAG or PCI prospectively. Patients were randomly assigned to probucol group (n = 102) and control group (n = 103). In the probucol group, the patients received probucol tablets 500 mg b.i.d for 3 days before and after intervention. All the patients, after intervention, underwent hydration with intravenous saline at a rate of 1 ml per kilogram of body weight per hour for 12 hours.

RESULTS

Patients were well-matched with no significant difference at baseline in majority measured parameters between two groups. CIAKI occurred in 23 of the 205 (11.22%) patients. Multivariate logistic regression was used to identify correlates of CIAKI and clinical data. CIAKI was most strongly associated with Scr > or = 132.6 micromol/L (OR = 21.11, 95%CI 1.95 - 56.06, P < 0.001), Ccr < 60 ml/min (OR = 4.19, 95%CI 1.94 - 9.05, P < 0.001), heart function > class II (OR = 6.23, 95%CI 2.73 - 14.21, P < 0.001), Diabetes (OR = 2.049, 95%CI 1.19 - 5.25, P < 0.001), age > or = 70 yrs (OR = 3.52, 95%CI 1.66 - 7.43, P < 0.001), coronary artery calcification shown by CAG (OR = 4.29, 95%CI 1.99 - 9.24, P < 0.001). The rate of CIAKI in probucol groups was slightly lower compared with control group (7.84% vs. 14.56%), without significant difference. The post-procedure mean peak of Scr [(101.62 +/- 42.98) micromol/L vs. (117.67 +/- 68.77) micromol/L, P = 0.047] and the post-procedure increasing Scr from baseline (DeltaScr) [(13.49 +/- 19.61) micromol/L vs. (22.50 +/- 18.31) micromol/L, P = 0.001] in the probucol group decreased significantly compared with that of control group.

CONCLUSION

Prophylactic treatment with probucol 500 mg b.i.d during periprocedural stage in patients with UAP has preventing role against CIAKI after cardiac catheterization.

[Preclinical and clinical studies of the efficacy of Panavir in therapy for tick-borne encephalitis]

The antiviral activity of Panavir was studied on a model of mice infected with the strain Sofjin of tick-borne encephalitis (TBE) virus. The efficacy of Panavir was studied in the treatment of the chronic (monotherapy; 30 patients) and acute febrile and meningeal (combined therapy; n = 113) forms of TBE. Panavir was found to have a positive effect on the clinical course of TBE and the immune mechanisms of the body's protection.

Probucol attenuates atrial autonomic remodeling in a canine model of atrial fibrillation produced by prolonged atrial pacing

BACKGROUND

We hypothesize that increased atrial oxidative stress and inflammation may play an important role in atrial nerve sprouting and heterogeneous sympathetic hyperinnervation during atrial fibrillation (AF). To test the hypothesis, we examined whether the antioxidant and anti-inflammatory treatment with probucol attenuates atrial autonomic remodeling in a canine model of AF produced by prolonged rapid right atrial pacing.

METHODS

Twenty-one dogs were divided into a sham-operated group, a control group and a probucol group. Dogs in the control group and probucol group underwent right atrial pacing at 400 beats per minute for 6 weeks, and those in the probucol group received probucol 1 week before rapid atrial pacing until pacing stopped. After 6-week rapid atrial pacing, general properties including left atrial structure and function, atrial hemodynamics and the inducibility and duration of AF were measured in all the groups. Atrial oxidative stress markers and serum C-reactive protein (CRP) concentration were estimated. The degree of nerve sprouting and sympathetic innervation at the right atrial anterior wall (RAAW) and the left atrial anterior wall (LAAW) were quantified by immunohistochemistry, atrial norepinephrine contents were also detected. Atrial beta-nerve growth factor (beta-NGF) mRNA and protein expression at the RAAW and LAAW were assessed by real-time quantitative RT-PCR and Western blotting respectively.

RESULTS

Atrial tachypacing induced significant nerve sprouting and heterogeneous sympathetic hyperinnervation, and the magnitude of nerve sprouting and hyperinnervation was higher in the RAAW than in the LAAW. Atrial beta-NGF mRNA and protein levels were significantly increased at the RAAW and LAAW, and the upregulation of beta-NGF expression was greater at the RAAW than at the LAAW in the control group. The beta-NGF protein level was positively correlated with the density of sympathetic nerves in all groups. Probucol decreased the increase of CRP concentration and attenuated atrial oxidative stress caused by atrial tachypacing. In addition, probucol could effectively inhibit atrial beta-NGF upregulation, significantly attenuate atrial nerve sprouting and heterogeneous sympathetic hyperinnervation, and dramatically reduce the inducibility and duration of AF.

CONCLUSIONS

The atrial over-expression of beta-NGF possibly caused by increased oxidative stress and inflammation may be the main mechanism underlying atrial autonomic remodeling during AF. Probucol attenuates atrial autonomic remodeling possibly by its antioxidant and anti-inflammatory actions.

[Coronary artery bypass graft in adolescent suffering from homozygous familial hypercholesterolemia resistant to probucol therapy]

Homozygous familial hypercholesterolemia is a rare hypercholesterolemia representing 1 to 2% of hypercholesterolemia. It is a metabolic disorder coming from genetic trouble with a bad prognostic. Its probucol's therapy in an adolescent is subject of controversy. The authors report a new case diagnosed in an adolescent of 15-year-old followed after CABG in the Thoracic and cardiovascular surgery Department of National Heart Institute Imbaba-Cairo (Egypt).

Effects of succinobucol (AGI-1067) after an acute coronary syndrome: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Oxidative stress and inflammation are involved in the pathophysiology of atherosclerosis. Our aim was to assess the effects of the antioxidant succinobucol (AGI-1067) on cardiovascular outcomes in patients with recent acute coronary syndromes already managed with conventional treatments.

METHODS

After an acute coronary syndrome occurring 14-365 days before recruitment, 6144 patients were randomly assigned with a computer-generated randomisation list, stratified by study site, to receive succinobucol (n=3078) or placebo (n=3066) in addition to standard of care. Enrolment began in July, 2003; this event-driven trial was stopped in August, 2006, after the prespecified number of primary outcome events had occurred. The composite primary endpoint was time to first occurrence of cardiovascular death, resuscitated cardiac arrest, myocardial infarction, stroke, unstable angina, or coronary revascularisation. Efficacy analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00066898.

FINDINGS

All randomised patients were included in the efficacy analyses. Succinobucol had no effect on the primary endpoint (530 events in succinobucol group vs 529 in placebo group; hazard ratio 1.00, 95% CI 0.89-1.13, p=0.96). The composite secondary endpoint of cardiovascular death, cardiac arrest, myocardial infarction, or stroke occurred in fewer patients in the succinobucol group than in the placebo group (207 vs 252 events; 0.81, 0.68-0.98, p=0.029). The tertiary endpoint of new-onset diabetes developed in fewer patients without diabetes at baseline in the succinobucol group than in such patients in the placebo group (30 of 1923 vs 82 of 1950 patients; 0.37, 0.24-0.56, p<0.0001). New-onset atrial fibrillation occurred more often in the succinobucol group than in the placebo group (107 of 2818 vs 55 of 2787 patients; 1.87, 1.67-2.09, p=0.0002). Although the number of patients who reported any treatment emergent adverse event was much the same in the two groups, more patients in the succinobucol group than in the placebo group reported bleeding episodes or anaemia (32 vs 18 and 37 vs ten, respectively) as serious adverse events. Relative to treatment with placebo, succinobucol increased LDL cholesterol and systolic blood pressure, and decreased HDL cholesterol and glycated haemoglobin (p<0.0001 for all).

INTERPRETATION

Although succinobucol had no effect on the primary endpoint, changes in the rates of other clinical outcomes-both beneficial and harmful-will need to be further assessed before succinobucol is used in patients with atherosclerosis or as an antidiabetic agent.

[Investigation of antiviral properties of new formulations of Panavir in the treatment of experimental herpes virus infection in mice]

Protective action of Panavir was studied in the treatment of experimental herpes virus infection on albino mice. It was shown, that intravenous and rectal Panavir formulations were able to increase survival of the experimental animals (decreased lethality) infected by HSV-1.

Antioxidants: the good, the bad and the ugly

Inflammation has a fundamental role in mediating all stages of atherosclerotic disease. The key role of oxidation in linking lipids and inflammation to atherosclerosis is compelling and is supported by experimental evidence. However, the relevance of the antioxidant hypothesis for the treatment of patients with atherosclerosis has not been definitively proven. Results of randomized trials with 'antioxidant' vitamins have been disappointing, and there are potentially important problems associated with their use, including their potential pro-oxidant effects. Probucol has reduced postpercutaneous coronary intervention (PCI)-restenosis and progression of carotid atherosclerosis in clinical trials. The antioxidant vascular protectant AGI-1067 has also been effective at preventing atherosclerosis in all tested animal models. The nonintervened reference coronary segments of the PCI vessel demonstrated improvements with AGI-1067 in the Canadian Antioxidant Restenosis Trial-1 (CART-1), evidence supportive of a clinical effect on slowing atherosclerosis progression. Two trials test the antioxidant/anti-inflammatory hypothesis with AGI-1067; CART-2 assesses its value for the reduction of both atherosclerosis progression and post-PCI restenosis, and Aggressive Reduction of Inflammation Stops Events (ARISE), which is evaluating its effects on hard cardiovascular outcomes.

Pharmacologic approaches to restenosis prevention

Despite significant advances in technology and technique, coronary restenosis remains the primary limitation of percutaneous transluminal coronary angioplasty (PTCA). Among patients undergoing PTCA, between 20% and 50% of patients who do not receive a stent and 10%-30% of those who do receive a stent develop restenosis within 6 months of the procedure. Drug-eluting stents, which release high local concentrations of antiproliferative or immunosuppressive agents directly into the vessel wall at the site of the lesion, have dramatically reduced the incidence of restenosis in patients undergoing PTCA. However, even with drug-eluting stents, a significant percentage of higher-risk patients develop in-stent restenosis. These data suggest that a role remains for effective, well-tolerated systemic pharmacologic therapies to further reduce the rate of restenosis. To date, the majority of systemic agents tested for restenosis prevention have failed to show significant benefit. Only 2 agents, probucol and cilostazol, have consistently demonstrated efficacy in preventing restenosis. In addition, the investigational agent AGI-1067 has demonstrated promising efficacy in early clinical trials. Together with drug-eluting stents, these therapies may for the first time reduce the rate of restenosis to near zero, even in high-risk patients, such as individuals with diabetes mellitus.

[Animal models for steroid-induced osteonecrosis]

We describe that high-dose methylprednisolone (20 mg/kg) can induce multifocal osteonecrosis (ON) in conjunction with thrombocytopenia, hypofibrinogenemia, and hyperlipemia. Detailed clinical and laboratory evaluations of coagulation system are recommended in those patients who develop manifestations of an abnormal lipid metabolism shortly after high-dose corticosteroid therapy. Moreover, we investigated the effects of the combination treatment with an anticoagulant (warfarin) plus a lipid-lowering agent (probucol) on prevention of steroid-induced osteonecrosis (ON) in this animal model. The incidence of ON in warfarin plus probucol (5%) was significantly lower than that observed in the control group (70%) (p <0.0001). Our results experimentally showed that the combined use of an anticoagulant and a lipid-lowering agent helps prevent steroid-induced ON in rabbits.

Probucol therapy overcomes the reproductive defect in CTP: phosphocholine cytidylyltransferase beta2 knockout mice

The synthesis of phosphatidylcholine (PtdCho), the major phospholipid in mammalian cells, is regulated by the CTP:phosphocholine cytidylyltransferase (CCT). Loss of the CCTbeta2 isoform expression in mice results in gonadal dysfunction. CCTbeta2(-/-) females exhibit ovarian tissue disorganization with progressive loss of follicle formation and oocyte maturation. Ultrastructure revealed a disrupted association between ova and granulosa cells and disorganized Golgi apparati in oocytes of CCTbeta2(-/-) mice. Probucol is a cholesterol-lowering agent that stimulates the uptake and retention of lipids carried by lipoproteins in peripheral tissues. Probucol therapy significantly lowered both serum cholesterol and PtdCho levels. Probucol therapy increased fertility in the CCTbeta2(-/-) females 100%, although it did not completely correct the phenotype, the morphological abnormalities in the knockout ovaries or itself stimulate CCT activity directly. These data indicated that a deficiency in de novo PtdCho synthesis could be complemented by altering the metabolism of serum lipoproteins, an alternative source for cellular phospholipid.

Probucol modulates iron nitrilotriacetate (Fe-NTA)-dependent renal carcinogenesis and hyperproliferative response: diminution of oxidative stress

Probucol is a clinically used cholesterol-lowering drug, with pronounced antioxidant properties. We have reported previously, that dietary supplementation of probucol enhances NAD(P)H:quinone reductase (Iqbal M, Okada S (2003) Pharmacol Toxicol 93:259-263) and inhibits Fe-NTA induced lipid peroxidation and DNA damage in vitro (Iqbal M, Sharma SD, Oakada (2004) Redox Rep 9:167-172). Further to this, in the present study, we evaluated the modulatory effect of probucol on iron nitrilotriacetae (Fe-NTA) dependent renal carcinogenesis, hyperproliferative response and oxidative stress. In Fe-NTA alone treated group, a 20% renal cell tumor incidence was recorded whereas, in N-diethylnitrosamine (DEN)-initiated and Fe-NTA promoted animals, the percentage tumor incidence was increased to 70% as compared with untreated controls. No tumor incidence was recorded in DEN-initiated, nonpromoted group. Diet supplemented with 1.0% probucol fed prior to, during and after Fe-NTA treatment in DEN-initiated animals afforded >65% protection in renal cell tumor incidence. Probucol fed diet pretreatment also resulted a significant and dose dependent inhibition of Fe-NTA induced renal ornithine decarboxylase (ODC) activity. In oxidative stress studies, Fe-NTA alone treatment enhanced lipid peroxidation, accompanied by a decrease in the level of GSH, activities of antioxidants and phase II metabolizing enzymes in kidney concomitant with histolopathological changes. These changes were significantly and dose-dependently alleviated by probucol fed diet. From this data, it can be concluded that probucol can modulates toxic and tumor promoting effects of Fe-NTA and can serve as a potent chemopreventive agent to suppress oxidant induced tissue injury and carcinogenesis, in addition to being a cholesterol lowering and anti-atherogenic drug.

Beneficial synergistic effects of concurrent treatment with cilostazol and probucol against focal cerebral ischemic injury in rats

In the present study, we assessed the beneficial synergistic effects of concurrent treatment with low doses of cilostazol and probucol against focal cerebral ischemic infarct in rats. The ischemic infarct induced by 2-h occlusion of middle cerebral artery (MCA) and 22-h reperfusion was significantly reduced in rat brain that received cilostazol (20 mg/kg) and probucol (30 mg/kg) twice together with prominent improvement of neurological function compared to the effect of cilostazol or probucol monotherapy. Increased myeloperoxidase activity, a marker of neutrophil infiltration, observed in the penumbral zone of vehicle-treated brain was more significantly reduced by cilostazol plus probucol in combination. Increased superoxide-, nitrotyrosine (a marker of peroxynitrite)-, poly(ADP-ribose) [a marker for poly(ADP-ribose) polymerase activity]-, and cleaved caspase-3-positive cells (a proapoptotic marker) in the vehicle sample were significantly attenuated by the combination therapy, while individual treatment with low dose of cilostazol or probucol showed a marginal effect. Taken together, it is suggested that the neuroprotective potentials of combination therapy with low doses of cilostazol plus probucol may provide beneficial therapeutic intervention in reducing the focal cerebral ischemic infarct in rats.

Vascular cell adhesion molecule-1: a viable therapeutic target for atherosclerosis?

Atherosclerosis is now well recognised as a chronic inflammatory process which may ultimately lead to myocardial infarction, stroke and peripheral vascular disease. The role of inflammation in the pathogenesis of atherosclerosis has lead to interest in developing therapies that target vascular inflammation. Leucocytes play a key role during atherosclerotic plaque development. Activated vascular endothelium expresses vascular cell adhesion cell molecule-1 (VCAM-1), a member of the adhesion molecule superfamily, to which monocytes and lymphocytes can bind. These inflammatory cells can then move through the endothelium by diapedesis and release cytokines and enzymes, important components in the progression of the lesion. Researchers have demonstrated that the extent of atherosclerotic lesions is significantly reduced in animal models with decreased VCAM-1 expression. VCAM-1 has therefore been identified as a potential anti-inflammatory therapeutic target, the hypothesis being that reduced expression of VCAM-1 will slow the development of atherosclerosis. Succinobucol (AGI-1067), an anti-oxidant compound also capable of inhibiting VCAM-1 gene expression, is an example of such an agent and is currently being investigated in a phase III cardiovascular end-point trial due to report in 2007. If the results are positive, further investigations should derive to what extent blockade of VCAM-1 by succinobucol, rather than its other effects, accounts for the reduction in vascular events.

Effects of Acetylcysteine and Probucol on Contrast Medium-induced Depression of Intrinsic Renal Glutathione Peroxidase Activity in Diabetic Rats

BACKGROUND

Antioxidants such as N-acetylcysteine and probucol have been used to protect patients from contrast media-induced nephrotoxicity. The mechanisms underlying these protective effects are not well understood. We hypothesized that acetylcysteine and probucol alter the activity of endogenous antioxidant enzyme activity.

METHODS

Four weeks after induction of diabetes with streptozotocin, diabetic and nondiabetic rats were divided into three groups. Group 1 rats did not receive any antioxidant agents. Group 2 rats were treated with acetylcysteine and group 3 rats with probucol for 1 week before injection of the contrast medium diatrizoate (DTZ).

RESULTS

We found that diabetic rats had higher renal glutathione peroxidase (GPx) activity than normal rats. DTZ suppressed renal GPx activity significantly in both group 1 diabetic and normal rats. Interestingly, renal GPx activity in both diabetic and normal rats pretreated with acetylcysteine or probucol was not inhibited by DTZ. Renal superoxide dismutase (SOD) increased significantly in normal rats after DTZ injection, but not in diabetic rats. Finally, acetylcysteine or probucol did not significantly influence renal SOD.

CONCLUSIONS

These findings suggest that the renal protective effects of acetylcysteine and probucol against contrast-induced oxidative stress and nephrotoxicity may be mediated by altering endogenous GPx activity.