Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Probucol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed2006

Chemical structure-dependent gene expression of proteasome subunits via regulation of the antioxidant response element.

Antioxidants possess potent ability to regulate gene expression beyond their specific antioxidant activity. Genomic analysis reveals that three phenolic antioxidants, probucol, BO-653, and tBHQ, all of which have a phenoxyl group with one or two tert-butyl groups at the ortho-position, inhibit both the mRNA and protein levels of proteasome alpha-subunits in human endothelial cells. The chemical structure required for the gene regulation was studied by using derivatives of BO-653 and other antioxidants. It was found that the phenoxyl group and tert-butyl group at the ortho-position of the compounds were critical for down-regulation of the proteasome gene. Two antioxidant responsive elements (AREs) were identified in the promoter region of proteasome alpha subunit 3 (PSMA3). Results from promoter truncation analysis revealed that the proximal ARE region was necessary for the down-regulation of the expression of PSMA3. Electrophoretic mobility shift assays revealed that BO-653-mediated induction of DNA-binding to an upstream promoter region of PSMA3 containing the ARE motif was blocked by antibody against c-Jun but not Nrf2. These results indicate that the suppression of the proteasome alpha subunits expression by phenolic antioxidants is strictly dependent on both their chemical structure and the ARE consensus region in the promoter, which may be negatively regulated by AP-1.

Animals↗
PubMed2006

Cyclic diarylheptanoids inhibit cell-mediated low-density lipoprotein oxidation.

Two cyclic diarylheptanoids, garugamblin-3 (1) and acerogenin L (2), isolated from the MeOH extract of the fruits of Alnus japonica Steud., inhibited human low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance assay with IC50 values of 2.9 and 1.7 microM, respectively, and they also inhibited cell-mediated LDL oxidation more than five times more strongly than that of a well-known antioxidant, probucol, at a concentration of 10 microM. 1 had no effect on the anti-atherogenesis in low-density lipoprotein receptor- deficient mice.

Alnus↗
PubMed2006

Cyclic diarylheptanoids inhibit cell mediated low-density lipoprotein oxidation.

Two cyclic diarylheptanoids, garugamblin-3 (1) and acerogenin L (2), isolated from the MeOH extract of the fruits of Alnus japonica Steud., inhibited human low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance assay with IC(50) values of 2.9 and 1.7 microM, respectively, and they also inhibited cell-mediated LDL oxidation more than 5 times more strongly than that of a well-known antioxidant, probucol, at a concentration of 10 microM. Compound (1) had no effect on the anti-atherogenesis in low-density lipoprotein receptor-deficient mice.

Alnus↗
PubMed1996

The antioxidant and antiatherogenic effects of MAK-4 in WHHL rabbits.

Oxidized low-density lipoprotein (ox-LDL) plays an important role in atherogenesis. Atheroma formation is reduced significantly in Watanabe heritable hyperlipidemic (WHHL) rabbits by antioxidants such as probucol and vitamin E. The herbal mixture Maharishi Amrit Kalash-4 (MAK-4) inhibits Cu+2 -induced LDL oxidation, and enzymatic- and nonenzymatic-induced microsomal lipid peroxidation. We tested the effect of MAK-4 on the development of atheroma in WHHL rabbits. Eleven rabbits were divided into two groups: controls (n = 5) and a group fed 6% (w/w) MAK-4 (n = 6). Blood was drawn for biochemical analysis every two months and at necropsy, six months after the special diet was started. The aortas were preserved in formalin. The percentage area of aortic arch covered with visible plaque in the MAK-4 group (22.5 +/- 4.2%, mean +/- SE) was significantly reduced (p < 0.01) compared to the control group (47.6 +/- 6.8%, mean +/- SE). The MAK-4 group showed a significant decrease (p < 0.05) in lipid peroxide, and a significant increase (p < 0.05) in glutathione peroxidase and resistance of LDL to endothelial cell-induced and cupric ion-catalyzed oxidation (4.5 h and 5 h lag phase, respectively, for the MAK-4 group; 0 h lag phase for both for the controls). These findings suggest MAK-4 reduces atheroma formation through its antioxidant activity.

Animals↗
PubMed1995

Dietary and pharmacologic regimens to reduce lipid peroxidation in non-insulin-dependent diabetes mellitus.

Persons with diabetes are at increased risk for developing coronary heart disease (CHD): although the standard risk factors are also applicable, there are other major nontraditional risk factors for these persons. For example, oxidation of lipoproteins may play an important role in the development of atherosclerosis. Another risk factor is the presence of small, dense low-density lipoprotein (LDL), which may have enhanced atherogenicity because it enters the arterial wall more readily and is more easily oxidized. Both of these factors may be particularly important in persons with non-insulin-dependent diabetes mellitus (NIDDM), because these persons may have greater rates of lipid oxidation in vivo than do nondiabetic persons and also have an increased prevalence of small, dense LDL. I describe potential dietary and pharmacologic regimens in patients with NIDDM to decrease in vivo lipid peroxidation, and the susceptibility of LDL and dense LDL subfractions to oxidative modification. In nearly all NIDDM patients, reducing dietary saturated fat helps lower plasma cholesterol and reduces the risk for CHD. There is, however, some controversy as to whether dietary saturated fat should be replaced by carbohydrates or by monounsaturated fatty acids (MUFAs) in NIDDM. Recent studies showed reduced susceptibility to oxidation of LDL in subjects consuming MUFA-enriched diets, thus adding another dimension to the ongoing debate over the most appropriate diet for NIDDM patients. Additionally, supplemental antioxidants such as probucol and vitamin E alone or in combination with MUFA-enriched diets have shown promise in protecting LDL from oxidation when given to nondiabetic populations. I also present recent results from an antioxidant trial in NIDDM subjects.

Aged↗
PubMed2001

Treatment of hyperlipidemia in HIV-infected patients.

The treatment of hyperlipidemia in patients infected with HIV is discussed. Hyperlipidemia is common in HIV-infected patients receiving antiretroviral therapy, especially protease inhibitors and stavudine. The recommendations of the National Cholesterol Education Program (NCEP) may not entirely apply to HIV-infected patients. The pathogenesis of hyperlipidemia in these patients may make them refractory to traditional pharmacotherapy, and NCEP's emphasis on diet and exercise may be unrealistic. Other factors that may complicate treatment of hyperlipidemia include metabolism of many antiretroviral drugs by the cytochrome P-450 isoenzyme system, polypharmacy, and drug-food interactions. A patient's cardiac risk should first be assessed. Nonpharmacologic measures, such as a low-fat diet, weight reduction, and exercise, should be considered. Drug therapy is indicated for patients with familial combined hyperlipidemia that is associated with atherogenesis and for patients with triglyceride concentrations exceeding 1000 mg/dL. Drug therapy for hyperlipidemia involves niacin and statins, in addition to fibric acid derivatives and probucol. Switching among antiretroviral agents when one is found to cause hyperlipidemia should be done cautiously because of the risk for viral rebound and disease progression. NCEP guidelines recommend monitoring low-density-lipoprotein cholesterol levels four to six weeks after the start of lipid-lowering therapy and then at three months; more frequent monitoring may be necessary in HIV-infected patients. The treatment of hyperlipidemia in HIV-infected patients is complicated by their need for antiretroviral drugs, which can themselves contribute to lipid disorders.

Anti-HIV Agents↗
PubMed2000

Specific cellular responses to alpha-tocopherol.

In the last 10 years precise cellular functions of alpha-tocopherol, some of which are independent of its antioxidant/radical-scavenging ability, have been revealed. Absorption of alpha-tocopherol from the gut is a selective process. Other tocopherols are not absorbed or are absorbed to a lesser extent. At the post-translational level, alpha-tocopherol inhibits protein kinase C and 5-lipoxygenase and activates protein phosphatase 2A and diacylglycerol kinase. Some genes [platelet glycoprotein IV/thrombospondin receptor/class B scavenger receptor (CD36), alpha-tocopherol transfer protein (alpha-TTP), alpha-tropomyosin, connective tissue growth factor and collagenase] are affected by alpha-tocopherol at the transcriptional level. alpha-Tocopherol also inhibits cell proliferation, platelet aggregation, monocyte adhesion and the oxygen burst in neutrophils. Other antioxidants, such as beta-tocopherol and probucol, do not mimic these effects, suggesting a nonantioxidant, alpha-tocopherol-specific molecular mechanism.

Animals↗
PubMed2001

Nonantioxidant functions of alpha-tocopherol in smooth muscle cells.

Most tocopherols and tocotrienols, with the exception of alpha-tocopherol, are not retained by humans. This suggests that alpha-tocopherol is recognized uniquely; therefore, it may exert an exclusive function. alpha-Tocopherol possesses distinct properties that are independent of its prooxidant, antioxidant or radical-scavenging ability. alpha-Tocopherol specifically inhibits protein kinase C, the growth of certain cells and the transcription of the CD36 and collagenase genes. Activation events have also been seen on the protein phosphatase 2A (PP(2)A) and on the expression of other genes (alpha-tropomyosin and connective tissue growth factor). Neither ss-tocopherol nor probucol possessed the same specialty functions as alpha-tocopherol. Recently, we isolated a new ubiquitous cytosolic alpha-tocopherol binding protein (TAP). Its motifs suggest that it is a member of the hydrophobic ligand-binding protein family (CRAL-TRIO). TAP may also be involved in the regulation of cellular alpha-tocopherol concentration and alpha-tocopherol-mediated signaling.

Cells, Cultured↗
PubMed1996

Interactions between the sorbitol pathway, non-enzymatic glycation, and diabetic vascular dysfunction.

BACKGROUND: Many lines of evidence attest to a multifactorial pathogenesis of diabetic complications in humans and in animal models of diabetes. Increased sorbitol pathway metabolism and non-enzymatic glycation products have been implicated by many investigators in the pathogenesis of vascular and neural dysfunction as well as early vascular structural changes in animal models of diabetes. The present studies were undertaken to assess the mechanisms that mediate vascular dysfunction associated with these biochemical imbalances. METHODS: Three different animal models of diabetes were used: (1) rats with diabetes induced by injection of streptozotocin; (2) non-diabetic rats with acute hyperglycaemia of 5 h duration induced by i.v. glucose infusion at a rate sufficient to produce plasma glucose levels comparable to those in diabetic rats; and (3) the skin chamber granulation tissue model in which vessels in the chamber are exposed to buffer containing 5 or 30 mM glucose +/- pharmacological agents or 0.1 microM glycated rat serum albumin +/- pharmacological agents. Vascular function was assessed by injection of 11.3 microns 46Sc microspheres for quantification of blood flow and by injection of [125I] and [131I]bovine serum albumin for quantification of vascular albumin permeation. RESULTS: Vascular dysfunction induced by elevated glucose levels (increased blood flow and increased albumin permeation) in all three models was prevented by inhibitors of sorbitol pathway metabolism, inhibitors of nitric oxide synthesis and inhibitors of prostaglandin synthesis. In the skin chamber model vascular dysfunction induced by elevated glucose levels and by glycated rat serum albumin was prevented by superoxide dismutase, probucol and inhibitors of nitric oxide synthase. CONCLUSIONS: These observations suggest that vascular dysfunction induced by increased sorbitol pathway metabolism (caused by elevated glucose levels) and by products of non-enzymatic glycation (at normal glucose levels) is mediated by a common final pathway consistent with a scenario in which: increases superoxide production-->increases intracellular calcium levels-->increases nitric oxide synthesis-->increases blood flow and increases vascular permeability.

Animals↗
PubMed1999

Facile degradation of apolipoprotein B by radical reactions and the presence of cleaved proteins in serum.

A facile cleavage of peptide bonds of apolipoprotein B (apoB) by radical reaction is reported. When human LDL was subjected to oxidative damage using Cu2+, extensive degradation of apoB was observed based on immunoblotting. The degradation of apoB was inhibited by radical scavengers (beta-mercaptoethanol, butylated hydroxytoluene, and probucol) and promoted by a radical initiator [2, 2'-azobis(2-amidinopropane)dihydrochloride]. When human serum was treated with Cu2+, a similar cleavage pattern of apoB was observed. The cleaved apoB proteins were also detected in normal serum on the basis of immunoblots. These results suggest that apoB is highly reactive toward radicals in vitro and in vivo, with reaction resulting in the cleavage of peptide bonds.

Adult↗
PubMed1994

Oxidized lipoproteins in atherosclerosis and thrombosis.

Oxidized low density lipoproteins (LDL) and autoimmune antibodies against oxidized LDL have been demonstrated in human atherosclerotic lesions; they may enhance the progression of these lesions by 1) enhancing monocyte adhesion and macrophage foam cell generation; 2) inducing smooth muscle cell migration, proliferation, and foam cell generation; 3) enhancing platelet adhesion and aggregation, which may stimulate macrophage foam cell generation and smooth muscle cell proliferation; 4) triggering thrombosis; and 5) impairing vasodilation, which results in increased shear stress. The oxidation of LDL probably occurs in the arterial wall, where it is sequestered from circulating antioxidants. Atherosclerotic arterial walls contain increased levels of redox-active metal ions, and the LDL of patients with atherosclerotic cardiovascular disease are more susceptible to oxidation, possibly as a result of reduced endogenous antioxidants such as vitamin E. Dietary supplementation with vitamin E (up to 1,000 IU/day) or administration of probucol reduce the oxidation rate of LDL and may significantly decrease the risk of coronary heart disease.

Animals↗
PubMed2003

Oxidized low-density lipoprotein inhibits endothelium-dependent vasodilation by an antioxidant-sensitive, lysophosphatidylcholine-independent mechanism.

Previous studies have shown that oxidized low-density lipoprotein (LDL) can impair endothelial function and that this can be overcome in vivo by administration of vitamin E. However, it is unclear whether this effect of oxidized LDL is due to lysophosphatidylcholine or other components of oxidized LDL, and it is also uncertain if the protective effect of vitamin E is related to its antioxidant action. The objectives of the current study were to define how much of the effect of extensively oxidized LDL on endothelium-dependent relaxation (EDR) was in fact due to lysophosphatidylcholine, to determine if the effect of oxidized LDL involved oxidant stress to the endothelium, and, if so, to ascertain if this could be blocked by oxyradical scavengers or antioxidants. Endothelial function was assessed by measuring vasodilation in preconstricted rat mesenteric artery rings in response to acetylcholine. In the presence of 100 microg/mL oxidized LDL, 25-fold higher concentrations of acetylcholine were required for the same degree of vasorelaxation. Similar concentrations of native LDL or acetyl LDL had no effect, but 100 microg/mL phospholipase A(2)-treated LDL or 20 microM lysophosphatidylcholine produced a similar inhibition of EDR. Removal of more than 90% of lysophosphatidylcholine from oxidized LDL did not affect its ability to inhibit EDR, nor did treatment of oxidized LDL with borohydride. This effect of oxidized LDL was blocked by preincubation of arterial rings with vitamin E, probucol, or BO-653 (a potent lipophilic antioxidant), but not by superoxide dismutase. In contrast, the inhibition of EDR by lysophosphatidylcholine was unaffected by antioxidants. Calphostin C prevented the inhibition of EDR by oxidized LDL and lysophosphatidylcholine. These studies demonstrate that at least part of the effect of oxidized LDL on EDR is independent of lysophosphatidylcholine, lipid peroxides, and superoxide release but appears to involve intracellular oxidative stress and protein kinase C activation.

Acetylcholine↗
PubMed2004

Carvedilol inhibits basal and stimulated ACE production in human endothelial cells.

Angiotensin-converting enzyme (ACE) plays an important role in the pathophysiology of cardiovascular disease. We examined the effect of carvedilol, a cardiovascular drug, on basal and stimulated ACE production in human endothelial cells. Carvedilol (0.625-5 microM), in a concentration-dependent manner, inhibited basal and vascular endothelial growth factor (VEGF, 0.5 nM) or phorbol 12-myristate 13-acetate (PMA, 10 nM) induced ACE up-regulation. Carvedilol has non-selective beta-adrenoceptor and selective alpha1-adrenoceptor blocking activity, calcium channel blocking, and anti-oxidant activity. To study whether these activities were related to ACE down-regulation, endothelial cells were treated with metoprolol (1-10 microM), propranolol (1-10 microM), prazosin (1-5 microM), nicardipine (1-10 microM), probucol (1-100 microM), or ascorbic acid (1-100 microM). None of these compounds modified ACE. VEGF (0.5 nM) and PMA (10 nM) induced PKC phosphorylation, which was inhibited by co-treatment of cell cultures with carvedilol (5 microM). In conclusion, carvedilol inhibited basal and VEGF or PMA induced ACE up-regulation. Inhibition of PKC phosphorylation was probably involved in carvedilol action.

Carbazoles↗
PubMed1995

Angiographic trials of lipid-lowering therapy: an update.

The value of specific LDL apheresis in drug-resistant cases of hyperlipidaemia is reviewed, as well as new data on the prevention of new lesion formation, efficacy of therapy based on initial lipid levels, and the consequences of lipid lowering in the angioplasty setting. Studies undertaken in the carotid and femoral bed are included, as is a brief discussion of the use of probucol as an adjunct to lipid-lowering therapy. These studies have emerged on a backdrop of data focused more on reduction of clinical events than on morphologic changes. Studies on the clinical impact of lipid-lowering therapy are included to provide a linkage between the rationale and conclusions of the angiographic trials with the emerging demonstration that cholesterol lowering does indeed reduce both cardiovascular and total mortality without inducing significant noncardiovascular morbidity or mortality.

Arteriosclerosis↗
PubMed1999

Dietary and pharmacological antioxidants in atherosclerosis.

Antioxidants that inhibit LDL oxidation are thought to be potential anti-atherogenic compounds. The results of major human randomized trials with antioxidants have, however, been disappointing, except for probucol, which consistently inhibits restenosis. Similarly, animal intervention studies show that antioxidants do not generally inhibit atherosclerosis, although some compounds provide protection. Direct evidence for the oxidation of LDL causing atherosclerosis is needed. This article summarizes results from antioxidant intervention studies, and highlights some of the key issues that need to be addressed to link biochemical changes in the arterial wall more directly to the oxidation theory of atherosclerosis.

Animals↗
PubMedDate not supplied

Cardiovascular considerations with anthracycline use in patients with cancer.

Anthracyclines are important chemotherapeutic agents that are used for the treatment of various malignancies in both adults and children, but their usefulness has been limited by cardiotoxicity that is usually dose related. Oxidative injury appears to be the cause of myocardial dysfunction when using these drugs. Screening for early myocardial injury with troponin testing, echocardiography, and radionuclide examinations has reduced the incidence of chronic cardiac dysfunction. Various anthracycline analogues have been developed that have less cardiotoxicity. Dexrazoxane, an iron chelator, and the radioprotective agent amifostine protect against cardiac injury, thus allowing the use of higher doses of anthracyclines. Other strategies that have been evaluated are dietary glutamine supplementation and the use of the antioxidant probucol.

Anthracyclines↗
PubMedDate not supplied

Oxidative stress and pancreatic beta-cell dysfunction.

Oxidative stress is induced under diabetic conditions through various pathways, including the electron transport chain in mitochondria and the nonenzymatic glycosylation reaction, and is likely involved in progression of pancreatic beta-cell dysfunction developing in diabetes. beta-Cells are vulnerable to oxidative stress, possibly due to low levels of antioxidant enzyme expression. When oxidative stress was induced in vitro in beta cells, the insulin gene promoter activity and mRNA levels were suppressed, accompanied by the reduced activity of pancreatic and duodenal homeobox factor-1 (PDX-1) (also known as IDX-1/STF-1/IPF1), an important transcription factor for the insulin gene. The suppression of oxidative stress by a potent antioxidant, N-acetyl-l-cysteine or probucol, led to the recovery of insulin biosynthesis and PDX-1 expression in nuclei and improved glucose tolerance in animal models for type 2 diabetes. As a possible cause of this, we recently found that PDX-1 was translocated from the nucleus to the cytoplasm in response to oxidative stress. Furthermore, the addition of a dominant-negative form of c-Jun N-terminal kinase (JNK) inhibited the oxidative stress-induced PDX-1 translocation, suggesting an essential role of JNK in mediating the phenomenon. Taken together, the oxidative stress-mediated activation of the JNK pathway leads to nucleocytoplasmic translocation of PDX-1 and thus is likely involved in the progression of beta-cell dysfunction found in diabetes.

Animals↗
PubMed1993

Protection of islet cells from inflammatory cell death in vitro.

Islet cells cocultured with activated macrophages are lysed within 15 h in vitro. We showed previously that nitric oxide generated by macrophages is a major mediator of islet cell death. We have now probed several pathways to interfere with the chain of events leading to islet cell death. Scavenging of extracellular oxygen radicals by superoxide dismutase and catalase did not improve islet cell survival. Scavenging of extra- and intracellular oxygen radicals by two potent substances, citiolone and dimethyl-thiourea, also did not reduce islet cell lysis, while a lipid-soluble scavenger, probucol, provided partial protection. These findings argue against a synergistic action of nitric oxide and oxygen radicals in islet cell toxicity. The inhibition of poly(ADP-ribose)polymerase by 3-aminobenzamide significantly improved islet cell survival. Selective inhibitors of cyclooxygenase, such as indomethacin or acetylsalicylic acid, did not improve islet cell survival. Full protection was seen in the presence of NDGA, an inhibitor of lipoxygenase, and partial suppression was caused by BW755c, an inhibitor of both lipoxygenase and cyclooxygenase. We conclude that inflammatory islet cell death caused by activated macrophages involves the activation of arachidonic acid metabolism and of poly(ADP-ribose)polymerase, but that scavenging of oxygen free radicals provides little protection from lysis.

Animals↗