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Now showing items 49 - 64 of 383

  • In vitro metabolism of carbaryl by human cytochrome P450 and its inhibition by chlorpyrifos

    Jun Tang   Yan Cao   Randy L Rose   Ernest Hodgson  

    Carbaryl is a widely used anticholinesterase carbamate insecticide. Although previous studies have demonstrated that carbaryl can be metabolized by cytochrome P450 (CYP), the identification and characterization of CYP isoforms involved in metabolism have not been described either in humans or in experimental animals. The in vitro metabolic activities of human liver microsomes (HLM) and human cytochrome P450 (CYP) isoforms toward carbaryl were investigated in this study. The three major metabolites, i.e. 5-hydroxycarbaryl, 4-hydroxycarbaryl and carbaryl methylol, were identified after incubation of carbaryl with HLM or individual CYP isoforms and analysis by HPLC. Most of the 16 human CYP isoforms studied showed some metabolic activity toward carbaryl. CYP1A1 and 1A2 had the greatest ability to form 5-hydroxycarbaryl, while CYP3A4 and CYP1A1 were the most active in generation of 4-hydroxycarbaryl. The production of carbaryl methylol was primarily the result of metabolism by CYP2B6. Differential activities toward carbaryl were observed among five selected individual HLM samples with the largest difference occurring in the production of carbaryl methylol. Co-incubations of carbaryl and chlorpyrifos in HLM greatly inhibited carbaryl metabolism. The ability of HLM to metabolize carbaryl was also reduced by pre-incubation of HLM with chlorpyrifos. Chlorpyrifos inhibited the generation of carbaryl methylol, catalyzed predominately by CYP2B6, more than other pathways, correlating with an earlier observation that chlorpyrifos is metabolized to its oxon primarily by CYP2B6. Therefore, carbaryl metabolism in humans and its interaction with other chemicals is reflected by the concentration of CYP isoforms in HLM and their activities in the metabolic pathways for carbaryl.
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  • Method and system for processing multicast packets

    Provided are a method, system, and program for processing multicast packets. A multicast packet is received to transmit to destination addresses. A payload of the multicast packet is written to at least one packet entry in a packet memory. Headers are generated for the destination addresses and at least one descriptor is generated addressing the at least one packet entry in the packet memory including the payload to transmit to the destination addresses. For each destination address, at least one indicator is generated including information on the generated header for the destination address and the at least one descriptor, wherein indicators for the destination addresses address the at least one descriptor.
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  • Promulgating information on websites using servers

    A method uses web servers to promulgate information from one server to another, instead of promulgating the information by the user to each server individually. A first server receives a first request for promulgating web-information from a user, locally promulgates the web-information, and sends a second request to at least one second website server to instruct the second website server to locally promulgate the web-information. The selection of the second server is done according to a preset configuration file which includes a relationship mapping between the first website server and the second website server. The relationship mapping may provide the user information related to the second website server based on the user information related to the first website server. The present disclosure further discloses a communication apparatus and a communication system.
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  • Promulgating information on websites using servers

    A method uses web servers to promulgate information from one server to another, instead of promulgating the information by the user to each server individually. A first server receives a first request for promulgating web-information from a user, locally promulgates the web-information, and sends a second request to at least one second website server to instruct the second website server to locally promulgate the web-information. The selection of the second server is done according to a preset configuration file which includes a relationship mapping between the first website server and the second website server. The relationship mapping may provide the user information related to the second website server based on the user information related to the first website server. The present disclosure further discloses a communication apparatus and a communication system.
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  • The death domain-associated protein modulates activity of the transcription co-factor Skip/NcoA62

    Jun Tang   Howard Y. Chang   Xiaolu Yang  

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  • Use of propofol for office-based anesthesia: effect of nitrous oxide on recovery profile

    Jun Tang   Lei Chen   Paul F White   Ronald H Wender   Robert Naruse   Robert Kariger   Alexander Sloninsky  

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  • The modulatory properties of Si Jun Zi Tang enhancing anticancer of gefitinib by an integrating approach

    Li, Chunyu   Niu, Ming   Wang, Ruilin   Zhou, Xiao wei   Dong, Bin   Qi, Shuya   Chen, Wei   Zhang, Mingyu   Shi, Yafei   Li, RuiSheng   Li, Guohui  

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  • Oxygen permeation through a CO2-tolerant mixed conducting oxide (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ

    Jun Tang   Yanying Wei   Lingyi Zhou   Zhong Li   Haihui Wang  

    A novel K2NiF4-type oxide based on (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ (PLNCG) dense mixed conducting ceramic membrane was successfully prepared through a sol–gel route. The oxygen permeation flux through the membrane swept by pure CO2 was comparative to that swept by He. The oxygen permeation and the stability of PLNCG under pure CO2 were investigated in detail. A membrane with a thickness of 0.8 mm was steadily operated for 230 h with a constant oxygen permeation flux of 0.32 mL/(min cm2) at 975°C using pure CO2 as sweep gas. X-ray diffraction shows that PLNCG can maintain its fluorite phase, and no carbonates were observed, even when it was exposed to pure CO2 for a long time.
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  • Oxygen permeation through a CO2-tolerant mixed conducting oxide (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ

    Jun Tang   Yanying Wei   Lingyi Zhou   Zhong Li and Haihui Wang  

    A novel K2NiF4-type oxide based on (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ (PLNCG) dense mixed conducting ceramic membrane was successfully prepared through a sol–gel route. The oxygen permeation flux through the membrane swept by pure CO2 was comparative to that swept by He. The oxygen permeation and the stability of PLNCG under pure CO2 were investigated in detail. A membrane with a thickness of 0.8 mm was steadily operated for 230 h with a constant oxygen permeation flux of 0.32 mL/(min cm2) at 975°C using pure CO2 as sweep gas. X-ray diffraction shows that PLNCG can maintain its fluorite phase, and no carbonates were observed, even when it was exposed to pure CO2 for a long time.
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  • Promulgating information on websites using servers

    A method uses web servers to promulgate information from one server to another, instead of promulgating the information by the user to each server individually. A first server receives a first request for promulgating web-information from a user, locally promulgates the web-information, and sends a second request to at least one second website server to instruct the second website server to locally promulgate the web-information. The selection of the second server is done according to a preset configuration file which includes a relationship mapping between the first website server and the second website server. The relationship mapping may provide the user information related to the second website server based on the user information related to the first website server. The present disclosure further discloses a communication apparatus and a communication system.
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  • Modified Formulation of Layer Stresses Due to Internal Pressure of a Layered Vessel With Interlayer Gaps

    Shugen Xu   Weiqiang Wang   Mingda Song   Mengli Li   Jun Tang  

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  • Superconductivity in silicon and germanium polyhedra

    Jun Tang   Kazumi Sato   Zhaofei Li   Katsumi Tanigaki  

    Superconductivity is observed both in silicon and germanium polyhedral materials in Ba 24Si 100 and Ba 24Ge 100. The former superconducts at T c=1.4K and its T c decreases upon pressure, while the latter is superconducting at 150mK after the electronic phase transition at 200K and its T c rises to 3.8K with pressure. These characteristics are comparably discussed from the viewpoint of the density of states at the Fermi level experimentally derived both in Ba 24Si 100 and Ba 24Ge 100 from soft X-ray photoelectron spectroscopy and magnetic susceptibility measurements. [All rights reserved Elsevier].
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  • A practical approach for predicting fatigue reliability under random cyclic loading

    Jun Tang   Jie Zhao  

    The purpose of this paper is to provide a simple approach for reliability analysis based on fatigue or overstress failure modes of mechanical components, and explain how this integrated method carries out spectral fatigue damage and failure reliability analysis. In exploring the ability to predict spectral fatigue life and assess the reliability under a specified dynamics environment, a methodology for reliability assessment and its corresponding fatigue life prediction of mechanical components using a supply-demand interference approach is developed in this paper. Since the methodology couples dynamics analysis and stochastic analysis for fatigue damage and reliability prediction, the conversion of the duty cycle history for the reliability study of an individual component is also presented. Using the proposed methodology, mechanical component reliability can be predicted according to different mission requirements. For an explanation of this methodology, a probabilistic method of deciding the relationship between the allowable stress or fatigue endurance limit and reliability is also presented
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  • Detoxication of paraoxon by rat liver homogenate and serum carboxylesterases and A-esterases*

    Jun Tang   Janice E. Chambers  

    Abstract Paraoxon, the active metabolite of parathion, can be detoxified through a noncatalytic pathway by carboxylesterases and a catalytic pathway by calcium-dependent A-esterases, producing p-nitrophenol as a common metabolite. The detoxication patterns of carboxylesterases and A-esterases were investigated in vitro in the present study with a high tissue concentration (75 mg/mL rat liver homogenate or 50% rat serum solution) to more closely reflect enzyme concentrations in intact tissues. A final paraoxon concentration of 3.75 μM was used to incubate with liver homogenates or serum solutions for 5 seconds or 3, 5, 15, or 25 minutes; also 0.625, 1.25, 2.5, 3.125, 3.75, or 5.0 μM paraoxon (final concentration) was incubated with liver homogenates or serum solutions for 15 minutes. Phenyl saligenin cyclic phosphate and EDTA were used to inhibit carboxylesterases and A-esterases, respectively. Significant amounts of p-nitrophenol were generated with or without either inhibitor during a 15 minute incubation with paraoxon from low (0.625 μM) to high (5.0 μM) concentrations. The amount of p-nitrophenol generated via carboxylesterase phosphorylation was greater than via A-esterase–mediated hydrolysis in the initial period of incubation or when incubating with a low concentration of paraoxon. Plateau shape curves of p-nitrophenol concentration versus time or paraoxon concentration indicated that carboxylesterase phosphorylation was saturable. When incubated for long time intervals or with high concentrations of paraoxon, more p-nitrophenol was generated via A-esterase–mediated hydrolysis than from carboxylesterase phosphorylation. The ratio of paraoxon concentration to tissue amount used in in vitro assays of this study was equivalent to dosing a rat with toxicologically relevant dosages. These in vitro data suggest that both carboxylesterases and A-esterases detoxify paraoxon in vivo; carboxylesterases may be an important mode of paraoxon detoxication in initial exposures to paraoxon or parathion before they become saturated, whereas A-esterases may contribute to paraoxon detoxication in repeated exposures to paraoxon or parathion because they will not become inhibited and will remain catalytically active unlike the carboxylesterases. The importance of carboxylesterases in detoxication of paraoxon was verified by an in vivo study. In rats pretreated with tri-o-tolyl phosphate, an in vivo carboxylesterase inhibitor, brain acetylcholinesterase was significantly inhibited after intravenous exposure to parathion. No significant inhibition of brain acetylcholinesterase was observed in rats pretreated with corn oil. © 1999 John Wiley & Sons, Inc. J Biochem Toxicol 13: 261–268, 1999
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  • ChemInform Abstract: The Advance and Application of Rare Earth Perfluorooctanoate [RE(PFO)3]

    Jun Tang   Limin Wang   Shengying Wu   Dan Mao  

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  • Antenna selection scheme for multiple antennae

    Techniques to select an antenna from a plurality of antennae used for wireless communications are described. A first embodiment of the techniques is a method to select an antenna from a plurality of antennae. The method includes monitoring at least one antenna during a fraction of at least one preamble period of a frame to derive at least one quality indicator corresponding to the antenna; storing the quality indicator derived from monitoring the antenna during the fraction of the preamble period of a frame; and selectively switching to a selected antenna after a number of frames, based on the quality indicator. A second embodiment is another method to select an antenna from a plurality of antennae. These embodiments can be applied in several wireless communication applications using multiple antennae.
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