Evaluation and validation of a commercially available enzyme-linked immunosorbent assay for the neonicotinoid insecticide imidacloprid in agricultural samples     

Watanabe E  Eun H  Baba K  Arao T  Ishii Y  Endo S  Ueji M 《Journal of agricultural and food chemistry》2004,52(10):2756-2762

The performance of a commercially available microtiter plate ELISA kit for the determination of the neonicotinoid insecticide imidacloprid was evaluated for sensitivity, selectivity, influence of organic solvent used for extraction procedure, matrix interference originated from agricultural sample, accuracy, and method comparison with conventional HPLC analysis. The limit of detection for the kit (0.1 or 0.5 ng/mL) was determined. The working range (1-39 ng/mL) experimentally calculated on the basis of a criterion, which is determined as the range from I(20) to I(80), was comparable to that established by the manufacturer (1-50 ng/mL). The linearity of the standard curve based on the kit-assembled standard solutions agreed with the one based on the self-made standard solutions. Specificity studies indicate that the imidacloprid monoclonal antibody can readily distinguish the target compound from other structurally related neonicotinoid analogues and some metabolites, with the exception of clothianidin, the cross-reactivity of which was approximately 12%. To extract imidacloprid from an agricultural sample (apple) as simply and rapidly as possible, some extraction methods were examined. Consequently, the extraction method with hand-shaking for 5 min was the best among the examined methods. For the analysis of imidacloprid in apple samples, it was extracted directly with methanol and the extracts were diluted 10-fold (100-fold in the well) with water prior to ELISA analysis. No significant matrix interference was observed with the dilution factor. Recoveries of imidacloprid from fortified apple samples ranged from 87.7 to 112.0%. The results obtained with the ELISA kit correlated well with those by the reference method (conventional HPLC analysis) for apple samples (r > 0.998). These findings strongly indicate that the ELISA kit may be employed routinely for an on-site imidacloprid residue analysis of apple samples.  相似文献   

High-performance solid Acid fuel cells through humidity stabilization     

Boysen DA  Uda T  Chisholm CR  Haile SM 《Science (New York, N.Y.)》2004,303(5654):68-70

Although they hold the promise of clean energy, state-of-the-art fuel cells based on polymer electrolyte membrane fuel cells are inoperable above 100 degrees C, require cumbersome humidification systems, and suffer from fuel permeation. These difficulties all arise from the hydrated nature of the electrolyte. In contrast, "solid acids" exhibit anhydrous proton transport and high-temperature stability. We demonstrate continuous, stable power generation for both H2/O2 and direct methanol fuel cells operated at approximately 250 degrees C using a humidity-stabilized solid acid CsH2PO4 electrolyte.  相似文献   

Repeated and sudden reversals of the dipole field generated by a spherical dynamo action     

Li J  Sato T  Kageyama A 《Science (New York, N.Y.)》2002,295(5561):1887-1890

Using long-duration, three-dimensional magnetohydrodynamic simulation, we found that the magnetic dipole field generated by a dynamo action in a rotating spherical shell repeatedly reverses its polarity at irregular intervals (that is, punctuated reversal). Although the total convection energy and magnetic energy alternate between a high-energy state and a low-energy state, the dipole polarity can reverse only at high-energy states where the north-south symmetry of the convection pattern is broken and the columnar vortex structure becomes vulnerable. Another attractive finding is that the quadrupole mode grows, exceeding the dipole mode before the reversal; this may help to explain how Earth's magnetic field reverses.  相似文献   

N-cyclohexyl linoleamide: metabolism and cholesterol-lowering effect in rats     

H Nakatani  H Fukushima  A Wakimura  M Endo 《Science (New York, N.Y.)》1966,153(741):1267-1269

More than half of orally administered N-cyclohexyl linoleamide-car-boxyl-C(14) yl-CI was recovered from feces of rats, and 30 to 50 percent of the absorbed carbon-14 activity was excreted in urine. N-Cyclohexyl linoleamide had an inhibitory eflect on the absorption of cholesterol from the thoracic duct and caused a decrease in the deposition of cholesterol in the livers of rats that had been fed cholesterol.  相似文献   

Early origin and recent expansion of Plasmodium falciparum     

Joy DA  Feng X  Mu J  Furuya T  Chotivanich K  Krettli AU  Ho M  Wang A  White NJ  Suh E  Beerli P  Su XZ 《Science (New York, N.Y.)》2003,300(5617):318-321

The emergence of virulent Plasmodium falciparum in Africa within the past 6000 years as a result of a cascade of changes in human behavior and mosquito transmission has recently been hypothesized. Here, we provide genetic evidence for a sudden increase in the African malaria parasite population about 10,000 years ago, followed by migration to other regions on the basis of variation in 100 worldwide mitochondrial DNA sequences. However, both the world and some regional populations appear to be older (50,000 to 100,000 years old), suggesting an earlier wave of migration out of Africa, perhaps during the Pleistocene migration of human beings.  相似文献   

MET amplification leads to gefitinib resistance in lung cancer by activating ERBB3 signaling     

Engelman JA  Zejnullahu K  Mitsudomi T  Song Y  Hyland C  Park JO  Lindeman N  Gale CM  Zhao X  Christensen J  Kosaka T  Holmes AJ  Rogers AM  Cappuzzo F  Mok T  Lee C  Johnson BE  Cantley LC  Jänne PA 《Science (New York, N.Y.)》2007,316(5827):1039-1043

The epidermal growth factor receptor (EGFR) kinase inhibitors gefitinib and erlotinib are effective treatments for lung cancers with EGFR activating mutations, but these tumors invariably develop drug resistance. Here, we describe a gefitinib-sensitive lung cancer cell line that developed resistance to gefitinib as a result of focal amplification of the MET proto-oncogene. inhibition of MET signaling in these cells restored their sensitivity to gefitinib. MET amplification was detected in 4 of 18 (22%) lung cancer specimens that had developed resistance to gefitinib or erlotinib. We find that amplification of MET causes gefitinib resistance by driving ERBB3 (HER3)-dependent activation of PI3K, a pathway thought to be specific to EGFR/ERBB family receptors. Thus, we propose that MET amplification may promote drug resistance in other ERBB-driven cancers as well.  相似文献   

Pressure-induced denaturation of monomer beta-lactoglobulin is partially irreversible: comparison of monomer form (highly acidic pH) with dimer form (neutral pH)     

Ikeuchi Y  Nakagawa K  Endo T  Suzuki A  Hayashi T  Ito T 《Journal of agricultural and food chemistry》2001,49(8):4052-4059

This study was conducted to assess the effect of high hydrostatic pressure on monomer beta-lactoglobulin (BLg) at acid pH by fluorescence spectroscopy under pressure and by circular dichroism (CD) and (1)H NMR spectroscopies after release of pressure. The intrinsic (tryptophan) fluorescence measurement and the study of 8-anilinonaphthalene-1-sulfonate (ANS) binding to BLg indicated that at pH 2.0 the recovery of center of spectral mass or ANS fluorescence was almost complete upon pressure release. No difference in (1)H NMR spectra was observed between pressurized and unpressurized BLg. In addition, NMR detection of the H/D exchange of aromatic protein indicated that the conformation of the vicinity of tryptophan residues could be refolded almost completely after release of pressure. These results seemingly confirm that the pressure-induced denaturation of BLg at pH 2.0 is reversible. However, cis-parinaric acid binding ability of pressurized BLg was largely lost, although its retinol binding ability was the same as its unpressurized one. Furthermore, CD spectra of the far-UV region and 2D NMR spectra evidently revealed the difference in the conformation of the molecule between unpressurized and pressurized BLg. These results are interpreted as an existence of partially fragile structure in the BLg molecule by high pressure.  相似文献   

Effects of phosphate supply and elevated CO2 on root acid phosphatase activity in Pinus densiflora seedlings     

Mariko Norisada  Tetsuya Motoshige  Katsumi Kojima  Takeshi Tange 《植物养料与土壤学杂志》2006,169(2):274-279

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Extended glucuronidation is another major path of cyanidin 3-O-beta-D-glucopyranoside metabolism in rats     

Ichiyanagi T  Shida Y  Rahman MM  Hatano Y  Konishi T 《Journal of agricultural and food chemistry》2005,53(18):7312-7319

We previously determined that five rather hydrophobic metabolites appeared in blood plasma after oral administration of cyanidin 3-O-beta-D-glucopyranoside, but a group of hydrophilic metabolites still remained unidentified. In the present study, 12 hydrophilic metabolites found were collected from urine and plasma samples by high-performance liquid chromatography (HPLC) and then analyzed by tandem MS spectrometry. From the MS spectra, four metabolites out of 12 were assigned as glucuronides of cyanidin 3-O-beta-D-glucopyranoside and six out of 12 were glucuronides of the primary metabolites of cyanidin 3-O-beta-D-glucopyranoside (O-methyl cyanidin 3-O-beta-D-glucopyranoside). Extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside showed their maximum plasma concentrations at 15 and 60 min (or 30 min) after oral administration, respectively. Their maximum plasma concentrations ranged from 15 to 70 nM. From the profile of urinary-excreted anthocyanins after intravenous administration, it was deduced that extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside were mainly produced in the liver rather than by intestinal flora. The area under the plasma concentration curve was 0.25 micromol min/L for extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and 0.14 micromol min/L for O-methyl cyanidin 3-O-beta-D-glucopyranoside, respectively, when evaluated as cyanidin 3-O-beta-D-glucopyranoside equivalent, indicating that extended glucuronidation is a critical pathway in cyanidin 3-O-beta-D-glucopyranoside metabolism in rats.  相似文献   

Isolation of fecal Clostridium perfringens from broiler chickens and their susceptibility to eight antimicrobial agents for growth promotion     

Y Benno  K Endo  T Mitsuoka 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1988,50(3):832-834

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