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  • Comparative study on antioxidant effects and vascular matrix metalloproteinase-2 downregulation by dihydropyridines in renovascular hypertension. 21058008

    The vascular remodeling associated with hypertension involves oxidative stress and enhanced matrix metalloproteinases (MMPs) expression/activity, especially MMP-2. While previous work showed that lercanidipine, a third-generation dihydropyridine calcium channel blocker (CCB), attenuated the oxidative stress and increased MMP-2 expression/activity in two-kidney, one-clip (2K1C) hypertension, no previous study has examined whether first- or second-generation dihydropyridines produce similar effects. We compared the effects of nifedipine, nimodipine, and amlodipine on 2K1C hypertension-induced changes in systolic blood pressure (SBP), vascular remodeling, oxidative stress, and MMPs levels/activity. Sham-operated and 2K1C rats were treated with water, nifedipine 10 mg/kg/day, nimodipine 15 mg/kg/day, or amlodipine 10 mg/kg/day by gavage, starting 3 weeks after hypertension was induced. SBP was monitored weekly. After 6 weeks of treatment, quantitative morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin-stained sections. Aortic and systemic reactive oxygen species levels were measured by using dihydroethidine and thiobarbituric acid-reactive substances (TBARs), respectively. Aortic MMP-2 levels and activity were determined by gelatin zymography, in situ zymography, and immunofluorescence. Nifedipine, nimodipine, or amlodipine attenuated the increases in SBP in hypertensive rats by approximately 17% (P < 0.05) and prevented vascular hypertrophy (P < 0.05). These CCBs blunted 2K1C-induced increases in vascular oxidative stress and plasma TBARs concentrations (P < 0.05). All dihydropyridines attenuated the increases in aortic MMP-2 levels and activity associated with 2K1C hypertension. These findings suggest lack of superiority of one particular dihydropyridine, at least with respect to antioxidant effects, MMPs downregulation, and inhibition of vascular remodeling in hypertension.
    Document Type:
    Reference
    Product Catalog Number:
    AP160P
    Product Catalog Name:
    Rabbit Anti-Mouse IgG Antibody, HRP conjugate

  • 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is selectively toxic to primary dopaminergic neurons in vitro. 24718704

    Parkinson's disease (PD) is the second most common neurodegenerative disease. Much data has linked the etiology of PD to a variety of environmental factors. The majority of cases are thought to arise from a combination of genetic susceptibility and environmental factors. Chronic exposures to dietary factors, including meat, have been identified as potential risk factors. Although heterocyclic amines that are produced during high-temperature meat cooking are known to be carcinogenic, their effect on the nervous system has yet to be studied in depth. In this study, we investigated neurotoxic effects of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a highly abundant heterocyclic amine in cooked meat, in vitro. We tested toxicity of PhIP and the two major phase I metabolites, N-OH-PhIP and 4'-OH-PhIP, using primary mesencephalic cultures from rat embryos. This culture system contains both dopaminergic and nondopaminergic neurons, which allows specificity of neurotoxicity to be readily examined. We find that exposure to PhIP or N-OH-PhIP is selectively toxic to dopaminergic neurons in primary cultures, resulting in a decreased percentage of dopaminergic neurons. Neurite length is decreased in surviving dopaminergic neurons. Exposure to 4'-OH-PhIP did not produce significant neurotoxicity. PhIP treatment also increased formation of oxidative damage markers, 4-hydroxy-2-nonenal (HNE) and 3-nitrotyrosine in dopaminergic neurons. Pretreatment with N-acetylcysteine was protective. Finally, treatment with blueberry extract, a dietary factor with known antioxidant and other protective mechanisms, prevented PhIP-induced toxicity. Collectively, our study suggests, for the first time, that PhIP is selectively toxic to dopaminergic neurons likely through inducing oxidative stress.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Water in Pyridine

    Document Type:
    Application
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • ABCG2/BCRP decreases the transfer of a food-born chemical carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in perfused term human placenta. 18680760

    We have studied the role of ATP binding cassette (ABC) transporters in fetal exposure to carcinogens using 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) a known substrate for ABC transporters as a model compound. In perfusion of human term placenta, transfer of (14)C-PhIP (2 microM) through the placenta resulted in fetal-to-maternal concentration ratio (FM ratio) of 0.72+/-0.09 at 6 h. The specific ABCG2 inhibitor KO143 increased the transfer of (14)C-PhIP from maternal to fetal circulation (FM ratio 0.90+/-0.08 at 6 h, p<0.05) while the ABCC1/ABCC2 inhibitor probenecid had no effect (FM ratio at 6 h 0.75+/-0.10, p=0.84). There was a negative correlation between the expression of ABCG2 protein in perfused tissue and the FM ratio of (14)C-PhIP (R=-0.81, p<0.01) at the end of the perfusion. The expression of ABCC2 protein did not correlate with FM ratio of PhIP (R: -0.11, p=0.76). In addition, PhIP induced the expression of ABC transporters in BeWo cells at mRNA level. In conclusion, our data indicates that ABCG2 decreases placental transfer of (14)C-PhIP in perfused human placenta. Also, PhIP may modify ABC transporter expression in choriocarcinoma cells.
    Document Type:
    Reference
    Product Catalog Number:
    MAB4148
    Product Catalog Name:
    Anti-MRP2 Antibody, clone M2 I-4

  • Inhibitor of MYC identified in a Kröhnke pyridine library. 25114221

    In a fluorescence polarization screen for the MYC-MAX interaction, we have identified a novel small-molecule inhibitor of MYC, KJ-Pyr-9, from a Kröhnke pyridine library. The Kd of KJ-Pyr-9 for MYC in vitro is 6.5 ± 1.0 nM, as determined by backscattering interferometry; KJ-Pyr-9 also interferes with MYC-MAX complex formation in the cell, as shown in a protein fragment complementation assay. KJ-Pyr-9 specifically inhibits MYC-induced oncogenic transformation in cell culture; it has no or only weak effects on the oncogenic activity of several unrelated oncoproteins. KJ-Pyr-9 preferentially interferes with the proliferation of MYC-overexpressing human and avian cells and specifically reduces the MYC-driven transcriptional signature. In vivo, KJ-Pyr-9 effectively blocks the growth of a xenotransplant of MYC-amplified human cancer cells.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple

  • Effects of estradiol, phytoestrogens, and Ginkgo biloba extracts against 1-methyl-4-phenyl-pyridine-induced oxidative stress. 12777708

    Oxidative stress has been recently considered as a mediator of nerve cell death in several neurodegenerative diseases. We studied the effect of the parkinsonism-inducing toxine 1-methyl-4-phenyl-pyridine (MPP+) on several parameters of cell distress using native and neuronal PC12 cells. Then, since estrogens have been reported to prevent neuronal degeneration caused by oxidative damage, we investigated the ability of 17beta- estradiol (E2); two Ginkgo biloba extracts, EGb 761 and Cp 202; as well as two flavonoids, quercetin and kaempferol, to rescue PC12 cells submitted to MPP+- induced oxidative stress. Our results consistently show that both Ginkgo biloba extracts could prevent cell death in native and neuronal PC12 cells, while in neuronal PC12 cells also quercetin and E2 could reverse MPP+ neurotoxic effet. Western blot analysis demonstrated that MPP+ injuries might modulate dopamine transporter (DAT) protein expression but not estrogen receptor beta (ERbeta) protein expression. EGb 761 and Cp 202 also modulate DAT and ERbeta protein expression in neuronal cells. From these studies, we outline the importance of testing estrogen-like plant-derived molecules as potent antioxidants and examine their effect on protein expression.
    Document Type:
    Reference
    Product Catalog Number:
    AB1591P
    Product Catalog Name:
    Anti-Dopamine Transporter Antibody

  • Identification and biochemical characterization of unique secretory nucleases of the human enteric pathogen, Entamoeba histolytica. 17766245

    The ancient eukaryotic human pathogen, Entamoeba histolytica, is a nucleo-base auxotroph (i.e. lacks the ability to synthesize purines or pyrimidines de novo) and therefore is totally dependent upon its host for the supply of these essential nutrients. In this study, we identified two unique 28-kDa, dithiothreitol-sensitive nucleases and showed that they are constitutively released/secreted by parasites during axenic culture. Using several different molecular approaches, we identified and characterized the structure of EhNucI and EhNucII, genes that encode ribonuclease T2 family proteins. Homologous episomal expression of epitope-tagged EhNucI and EhNucII chimeric constructs was used to define the functional and biochemical properties of these released/secreted enzymes. Results of coupled immunoprecipitation-enzyme activity analyses demonstrated that these secretory enzymes could hydrolyze a variety of synthetic polynucleotides, as well as the natural nucleic acid substrate RNA. Furthermore, our results demonstrated that sera from acutely infected amebiasis patients recognized and immunoprecipitated these parasite secretory enzymes. Based on these observations, we hypothesize that within its host, these secretory nucleases could function, at a distance away from the parasite, to harness (i.e. hydrolyze/access) host-derived nucleic acids to satisfy the essential purine and pyrimidine requirements of these organisms. Thus, these enzymes might play an important role in facilitating the survival, growth, and development of this important human pathogen.
    Document Type:
    Reference
    Product Catalog Number:
    ECM600
    Product Catalog Name:
    uPA Activity Assay Kit