Millipore Sigma Vibrant Logo
 

cloro


373 Results Búsqueda avanzada  
Mostrar
Productos (317)
Documentos (29)
Páginas (27)

Acote sus resultados Utilice los filtros siguientes para refinar su búsqueda

Tipo de documento

  • (27)
  • (2)
¿No encuentra lo que está buscando?
Póngase en contacto con
el Servicio de Atención
al Cliente

 
¿Necesita ayuda para encontrar un documento?

  • Sensitive detection of DNA modifications induced by cisplatin and carboplatin in vitro and in vivo using a monoclonal antibody. 1703029

    An assay that is based upon a monoclonal antibody (ICR4) is described that enables the quantitation of cisplatin-induced adducts on DNA down to 3 nmol Pt/g DNA (i.e., 1 Pt adduct/10(6) bases), the level necessary to produce toxic effects in cells in vitro and in vivo, using just a few micrograms of DNA. Detection is possible below this level (although probably not necessary for in vivo studies) but the cross-reactivity of unmodified DNA sequences complicates absolute quantitation of adducts. Therefore, it will be possible to investigate the distribution of clinically useful platinum drugs in patients undergoing chemotherapy. Rats of strain F344 appeared to be the best, among several tested, for the production of antibodies to modified DNA, and they were used for the production of hybridomas. Fifteen hybridomas which secreted antibodies that bound to DNA that was highly modified with cisplatin but not to normal DNA were obtained. One (ICR4) was chosen for further characterization because of its relatively strong binding to DNA modified to a moderate level with cisplatin. The characterization included the development of a sensitive competitive enzyme-linked immunoabsorbent assay and the use of DNA that had been reacted with cisplatin both in vitro and in vivo. The levels of platination of both types of DNA samples were determined by atomic absorbance spectroscopy. For DNA that had been exposed to cisplatin in vitro, 50% inhibition of antibody binding was caused by about 15 fmol of total DNA-bound Pt/assay well. At moderate levels of platination, heating of the DNA solution at 100 degrees C for 5 min increased its immunoreactivity such that 50% inhibition was caused by 2.5 fmol Pt adducts/well. Pt adducts on DNA extracted from cells that had been treated with cisplatin were less immunoreactive than DNA treated with cisplatin in vitro, but after heating the immunoreactivity increased such that 50% inhibition in the assay was caused by 2 fmol Pt adduct/well. This sensitivity was invariant over a wide range of levels of platinum adduct frequency. DNA adducts formed by the second generation anticancer drug carboplatin were recognized similarly to the adducts formed by cisplatin, but those formed by the clinically inactive trans-diamminedichloroplatinum(II) or chloro(diethylenetriamine)-platinum(II)-chloride were not significantly immunoreactive. Control DNA cross-reacted in the competitive assay but the immunoreactivity per mol base was 10(7) times lower than the immunoreactivity of cisplatin adducts.
    Tipo de documento:
    Referencia
    Referencia del producto:
    ABE416

  • Atrazine Triggers DNA Damage Response and Induces DNA Double-Strand Breaks in MCF-10A Cells. 26114388

    Atrazine, a pre-emergent herbicide in the chloro-s-triazine family, has been widely used in crop lands and often detected in agriculture watersheds, which is considered as a potential threat to human health. Although atrazine and its metabolites showed an elevated incidence of mammary tumors in female Sprague-Dawley (SD) rats, no molecular evidence was found relevant to its carcinogenesis in humans. This study aims to determine whether atrazine could induce the expression of DNA damage response-related proteins in normal human breast epithelial cells (MCF-10A) and to examine the cytotoxicity of atrazine at a molecular level. Our results indicate that a short-term exposure of MCF-10A to an environmentally-detectable concentration of atrazine (0.1 µg/mL) significantly increased the expression of tumor necrosis factor receptor-1 (TNFR1) and phosphorylated Rad17 in the cells. Atrazine treatment increased H2AX phosphorylation (γH2AX) and the formation of γH2AX foci in the nuclei of MCF-10A cells. Atrazine also sequentially elevated DNA damage checkpoint proteins of ATM- and RAD3-related (ATR), ATRIP and phospho-Chk1, suggesting that atrazine could induce DNA double-strand breaks and trigger the DNA damage response ATR-Chk1 pathway in MCF-10A cells. Further investigations are needed to determine whether atrazine-triggered DNA double-strand breaks and DNA damage response ATR-Chk1 pathway occur in vivo.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-636
    Nombre del producto:
    Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301

  • Expression of the tyrosine kinase discoidin domain receptor 1 (DDR1) in human central nervous system myelin. 20380825

    During development of the mouse brain, the protein kinase discoidin domain receptor 1 (DDR1) is present prenatally in neurons of the proliferative areas, and postnatally, DDR1 expression is no longer detected in neurons, but a spatial-temporal expression pattern in oligodendrocytes that overlaps with the dynamics of the myelination process is detected. Notably, oligodendrocytic DDR1 expression is upregulated in mice during experimentally induced remyelination. Recently, we demonstrated that DDR1 expression is high in human brain and that there is an association between the gene and schizophrenia in a case-control study. However, data regarding expression of DDR1 in the human brain are scarce. Here, we describe the expression pattern of DDR1 in the human adult cerebral cortex. Using several immunohistological techniques and in situ hybridization, we identified DDR1 in the following: a) myelin, b) capillary endothelial cells in the gray as well as white matter, and c) in the soma of some oligodendrocytes and astrocytes in the white matter. The most important overall finding in this study was that DDR1 is present in myelin and is expressed by oligodendrocyte cells. We detected the presence of DDR1 mRNA and protein in myelin and observed that DDR1 co-localized with the classical myelin basic protein (MBP). Moreover, we found a strong positive correlation between expression levels of DDR1 and two myelin-associated genes, myelin-associated glycoprotein (MAG) and oligodendrocyte transcription factor 2 (OLIG2). These observations suggest that DDR1 could be an important constituent of myelin. Because defects in myelination are linked to several mental disorders such as schizophrenia, the function of DDR1 in the process of myelination warrants further investigation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB980

  • Signal pathway involved in the development of hypoxic preconditioning in rat hepatocytes. 11124829

    Ischemic preconditioning improves liver resistance to hypoxia and reduces reperfusion injury following transplantation. However, the intracellular signals that mediate the development of liver hypoxic preconditioning are largely unknown. We have investigated the signal pathway leading to preconditioning in freshly isolated rat hepatocytes. Hepatocytes were preconditioned by 10-minute incubation under hypoxic conditions followed by 10 minutes of reoxygenation and subsequently exposed to 90 minutes of hypoxia. Preconditioning reduced hepatocyte killing by hypoxia by about 35%. A similar protection was also obtained by preincubation with chloro-adenosine or with A(2A)-adenosine receptor agonist CGS21680, whereas A(1)-adenosine receptor agonist N-phenyl-isopropyladenosine (R-PIA) was inactive. Conversely, the development of preconditioning was blocked by A(2)-receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX), but not by A(1)-receptor antagonist 8-cyclopenthyl-1, 3-dipropylxanthine (DPCPX). In either preconditioned or CGS21680-treated hepatocytes a selective activation of delta and epsilon protein kinase C (PKC) isoforms was also evident. Inhibition of heterotrimeric G(i) protein or of phospholypase C by, respectively, pertussis toxin or U73122, prevented PKC activation as well as the development of preconditioning. MEK inhibitor PD98509 did not interfere with preconditioning that was instead blocked by p38 MAP kinase inhibitor SB203580. The direct activation of p38 MAPK by anisomycin A mimicked the protection against hypoxic injury given by preconditioning. Consistently, an increased phosphorylation of p38 MAPK was observed in preconditioned or CGS21680-treated hepatocytes, and this effect was abolished by PKC-blocker, chelerythrine. We propose that a signal pathway involving A(2A)-adenosine receptors, G(i)-proteins, phospholypase C, delta- and epsilon-PKCs, and p38 MAPK, is responsible for the development of liver ischemic preconditioning.
    Tipo de documento:
    Referencia
    Referencia del producto:
    3301

  • Stability of thiotepa (lyophilized) in 0.9% sodium chloride injection. 9397220

    The stability of thiotepa in a new formulation of the drug was studied. Vials of Thioplex (Immunex), a relatively new lyophilized formulation of thiotepa, were reconstituted with sterile water and diluted with 0.9% sodium chloride injection in polyvinyl chloride infusion bags to thiotepa concentrations of 0.5, 1, and 3 mg/mL. The solutions were stored at 8 and 25 degrees C in ambient light and analyzed at 0, 8, 24, and in most cases 48 hours for thiotepa concentration and chloro-adduct formation by stability-indicating high-performance liquid chromatography. Thiotepa 1 and 3 mg/mL was stable for 48 hours at 8 degrees C and for 24 hours at 25 degrees C. Thiotepa 0.5 mg/mL was not stable at either temperature. Storage at 8 degrees C slowed but did not prevent chloro-adduct formation and loss of potency. The pH tended to increase with time; turbidity remained low. Thiotepa (lyophilized) 1 and 3 mg/mL in 0.9% sodium chloride injection was stable for 48 hours at 8 degrees C and for 24 hours at 25 degrees C; the drug was unstable when diluted to 0.5 mg/mL and stored under the same conditions.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-457

  • Involvement of lysine residues in the gating of the ryanodine receptor/Ca2+-release channel of skeletal muscle sarcoplasmic reticulum. 9288920

    In this study, the modification of skeletal muscle ryanodine receptor (RyR)/Ca2+-release channel with 7-chloro-4-nitrobenzo-2-oxa-1,3,-diazole (Nbd-Cl) demonstrates that lysyl residues are involved in the channel gating. Nbd-Cl was found to have a dual effect: stimulation and inhibition of ryanodine binding and single channel activities. Nbd-Cl, in a time-dependent manner, first stimulated and subsequently inhibited ryanodine binding to both membrane-bound and purified RyR. Incubation of sacroplasmic reticulum membranes with Nbd-Cl for 5-20 s resulted in enhanced ryanodine-binding activity by 2-4-fold due, to an increased binding affinity by about tenfold, with no effect on the total binding sites (Bmax). However, under prolonged incubation (5-20 min), Nbd-Cl strongly inhibited ryanodine binding by decreasing the Bmax with no effect on the binding affinity. Similar effects of stimulation and inhibition by Nbd-Cl were obtained with single channel activity of RyR reconstituted into planar lipid bilayer. Nbd-Cl initially (within a few seconds) activated the channel to a highly open state, then (within a few minutes) inactivated it to the completely closed state. Nbd-Cl-modified protein, as assayed by ryanodine binding or single channel activities, was stable against thiolysis by dithiothreitol, suggesting Nbd-Cl modification of lysyl residues. Evidence from absorption and fluorescence excitation and emission spectra also demonstrated that lysyl residues in RyR were modified by Nbd-Cl. Spectrophotometric data were used to estimate a ratio of up to 1 mol Nbd bound/mol RyR (tetramer) and up to 4 mol Nbd bound per mol RyR (tetramer) for Nbd-Cl stimulated and inhibited RyR activities, respectively. The results clearly indicate the involvement of two classes of lysyl residues in RyR activity. Modification by Nbd-Cl of the fast-reacting group led to stimulation of ryanodine binding and single channel activities, while modification of the slow-reacting group resulted in inhibition of these activities. Thus, the involvement of lysine residues in the gating of the RyR channel is proposed.
    Tipo de documento:
    Referencia
    Referencia del producto:
    17-191
    Nombre del producto:
    MAP Kinase/Erk Assay Kit, non-radioactive

  • Iron dependent degradation of an isothiazolone biocide (5-chloro-2-methyl-4-isothiazolin-3-one). 17453731

    An isothiazolone biocide, 5-chloro-2-methyl-4-isothiazolin-3-one (CMI), was degraded in the presence of iron. According to the Fe-dependent degradation of CMI, stoichiometric production of chloride was observed. Copper and stainless steel did not enhance the physico-chemical degradation of CMI, whilst phosphate inhibited the Fe-dependent degradation. Neither aerobic nor anaerobic conditions influenced the Fe-dependent CMI degradation. Furthermore, FeO(OH)-powder and Fe(3)O(4)-powder did not lead to the physico-chemical degradation of CMI. Rapid disappearance of CMI was observed in an operating cooling water plant. CMI added to the cooling tower declined from 1.4 mg l(-1) to < 0.1 mg l(-1) in 2 d. This finding is important in optimising the use of CMI and combating resistance if encountered.
    Tipo de documento:
    Referencia
    Referencia del producto:
    04-083
    Nombre del producto:
    Anti-Ago1 Antibody, clone 6D8.2

  • An insulin-like growth factor 1 receptor inhibitor induces CYP3A4 expression through a pregnane X receptor-independent, noncanonical constitutive androstane receptor-rela ... 22171088

    Inhibition of insulin-like growth factor-1 receptor (IGF-1R) signaling represents an attractive therapeutic strategy for cancer treatment. A first-generation IGF-1R inhibitor (R)-4-(3-(3-chlorophenyl)-3-hydroxypropyl)-3-(4-methyl-6-morpholino-1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-one (BMS-536924), however, was associated with potent CYP3A4 induction mediated by pregnane X receptor (PXR; NR1I2) transactivation. Structural activity-based modification led to the synthesis of 4-(1-(2-(4-((2-(4-chloro-1H-pyrazol-1-yl)ethyl)amino)-2-oxo-1,2-dihydropyridin-3-yl)-4-methyl-1H-benzo[d]imidazol-6-yl)piperidin-4-yl) piperazine-1-carboxylate (BMS-665351) with no PXR activity while maintaining its ability to inhibit IGF-1R. However, BMS-665351 significantly induces CYP3A4 expression in human primary hepatocytes (HPHs). Here, we report a novel nonclassical constitutive androstane receptor (CAR; NR1I3)-related pathway of BMS-665351-mediated CYP3A4 induction. BMS-665351 treatment resulted in the significant induction of CYP3A4 in HPHs and HepG2 cells, but failed to activate either PXR or CAR in cell-based reporter assays. Moreover, BMS-665351 at concentrations that induce CYP3A4 expression was unable to translocate human CAR from the cytoplasm to the nucleus of HPHs, which represents the initial step of CAR activation. Nevertheless, quantitative polymerase chain reaction analysis demonstrated that BMS-665351 significantly enhanced the expression of CYP3A4 in CAR- but not PXR-transfected HepG2 and Huh7 cells. It is noteworthy that BMS-665351 selectively induced the expression of CAR but not PXR in all tested hepatic cell systems. Synergistic induction of CYP3A4 was observed in HPHs cotreated with BMS-665351 and prototypical activators of CAR but not PXR. In summary, our results indicate that BMS-665351-mediated induction of CYP3A4 is CAR-dependent, but BMS-665351 itself is not a typical activator of either CAR or PXR, rather it functions as a selective inducer of CAR expression and increases CYP3A4 through a noncanonical CAR-related mechanism.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB1254
    Nombre del producto:
    Anti-Cytochrome P450 Enzyme CYP3A4 Antibody