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1.
Arachidonate metabolites are potent mediators generated in endotoxin shock. Following endotoxin administration (15 mg/kg) into unanesthetized rats, we found a rapid biliary secretion of peptide leukotrienes. Analysis of bile for peptide leukotrienes included organic solvent extractions, reversed phase-HPLC, radioimmunoassay (RIA), and spectrophotometry. The major immunoreactive endogenous leukotriene (LT) from bile was eluted between LTC4 and LTD4 in three chromatographic systems. It corresponded thereby to a biliary metabolite of injected LTC4 and LTD4 which in turn showed the ultraviolet spectrum of a peptide leukotriene. This demonstration of endotoxin-induced generation of peptide LTs in vivo was possible by sequential HPLC and RIA analyses in bile into which peptide LTs are eliminated from blood. 相似文献
2.
Koidl J Hödl H Schmid MG Neubauer B Konrad M Petschauer S Gübitz G 《Journal of biochemical and biophysical methods》2008,70(6):1254-1260
This paper deals with the chiral separation of triiodothyronine (T3) and thyroxine (T4) by HPLC and micro-HPLC. The separation of T3 and T4 is of great pharmaceutical and clinical interest, since the enantiomers exhibit different pharmacological activities. The HPLC measurements were performed on a chiral stationary ligand-exchange phase using l-4-hydroxyproline bonded via 3-glycidoxypropyltrimethoxysilane to silica gel as a selector. Also a chiral teicoplanin (Chirobiotic ™®) phase was used.
In micro-HPLC the chiral separation behaviour of l-4-hydroxyproline, and of the macrocyclic antibiotics teicoplanin and teicoplanin aglycone was investigated for the enantioseparation of T3 and T4. l-4-Hydroxyproline was bonded to 3 μm and the glycopeptide antibiotics were bonded to 3.5 μm silica gel and separations were accomplished by microbore HPLC columns (10 cm × 1 mm I.D.). With both techniques and all chiral selectors investigated T3 and T4 were baseline resolved. micro-HPLC was found to be superior to analytical HPLC with respect to low consumption of packing material, mobile phase and analyte. 相似文献
3.
Farias SE Zarini S Precht T Murphy RC Heidenreich KA 《Journal of neurochemistry》2007,103(4):1310-1318
Leukotrienes are mediators of inflammation that belong to a family of lipids derived from arachidonic acid by the action of 5-lipoxygenase. Leukotrienes have been detected in the central nervous system in association with different pathological events, but little is known about their biosynthesis or function in the brain. When rat neurons and glial cells in primary culture were stimulated with the calcium ionophore, no significant biosynthesis of leukotrienes was detected using liquid chromatography/mass spectrometry (LC/MS) techniques. However, when exogenous LTA4 was added to these cultured cells, both neurons and glia were able to synthesize LTC4 . Activated neutrophils are known to supply LTA4 to other cells for transcellular biosynthesis of cysteinyl-leukotrienes. Since neutrophils can infiltrate brain tissue after stroke or traumatic brain injury, we examined whether neutrophils play a similar role in the central nervous system. When peripheral blood neutrophils were co-cultured with rat neurons, glia cells, and then stimulated with calcium ionophore, a robust production of LTC4 , LTD4 , and LTE4 was observed, revealing that neurons and glia can participate in the transcellular mechanism of leukotriene biosynthesis. The formation of LTC4 through this mechanism may be relevant in the genesis and progression of the inflammatory response as a result of brain injury. 相似文献
4.
Paroo Narsi Parmar Charles Alistair Brearley 《The Plant journal : for cell and molecular biology》1993,4(2):255-263
Components of the polyphosphoinositide signalling pathway have been identified in stomatal guard cells of Commelina communis L., one of the few plant systems shown unequivocally to be capable of responding to release of inositol 1,4,5-trisphosphate in the cytoplasm by increase in cytoplasmic Ca2+ . 'Isolated' epidermal strips of C. communis (in which all cells other than guard cells have been killed by treatment at low pH) were radiolabelled with myo -[2n-3 H]inositol or [32 P]orthophosphate for 17–18 h. The phosphoinositides and inositol phosphates were extracted. Phosphoinositides were deacylated and the head groups resolved by HPLC. The water-soluble products generated by mild periodate cleavage of HPLC-purified, deacylated lipid fractions were examined. The resulting biochemical analysis led to the identification of: PtdIns, PtdIns3 P , PtdIns4 P , PtdIns(3,4) P 2 and PtdIns(4,5) P 2 . Thex inositol phosphates were resolved by HPLC. Preliminary analysis of HPLC-purified putative inositol phosphate fractions resulted in the identification of each inositol phosphate class, that is, Ins P , Ins P 2 , Ins P 3 , Ins P 4 , Ins P 5 and InsP 6 . Many of these inositol phosphates occurred in different isomeric forms. The presence of 3-phosphorylated phosphoinositides suggests that they may have a role in signalling in stomatal guard cells. 相似文献
5.
Gibberellins A1 (GA1 ), GA4 , GA9 , GA19 , and GA20 were identified in extracts of leaves of Begonia x cheimantha Everett cv. Nova (Christmas or Lorraine Begonia). GA-like substances were purified by reverse phase and normal phase high performance liquid chromatography (HPLC) and detected by Tan-ginbozu dwarf rice bioassay and binding to antibodies raised against GA1 , GA4 and GA9 . The final identifications were made by gas chromatography—mass spectrometry (GC-MS). 相似文献
6.
Extracts of Douglas fir ( Pseudotsuga menziesii [Mirb.] Franco) shoots were purified by reversed and normal phase HPLC; gibberellin (GA)-like compounds detected by radioimmunoassay with antibodies against GA4 and the Tan-ginbozu dwarf rice micro-drop biossay were analyzed by GC-MS. Three major components were identified as GA4 , GA7 , and GA9 while smaller amounts of GA1 , GA3 and putative GA9 -glucosyl ester were also present. 相似文献
7.
Gibberellins Al (GA1 ), GA3 , GA4 , GA9 , and after enzymatic hydrolysis of GA-conjugate-like fractions, GA9 and GA15 , were identified in shoots of Sitka spruce [ Picea sitchensis (Bong.) Carr.] of different ages by combined gas chromatography-mass spectrometry (GC-MS). The purification and separation of the GAs involved the use of reverse phase and normal phase high performance liquid chromatography (HPLC). The Tan-ginbozu dwarf rice bioassay and binding to antibodies raised against GA1 , GA4 and GA9 were used for detection of GA-like substances. The qualitative differences between the three ages of plant material were the presence of GA3 and GA1 in the 48-year-old material and the absence of detectable amounts of GA4 in the same material. This indicates a difference in GA metabolism which may reflect the difference in ability to form reproductive buds. 相似文献
8.
W. O. Jones R. G. Windon J. W. Steel P. M. Outteridge 《International journal for parasitology》1990,20(8):1075-1079
Lambs selectively bred for high responsiveness or low responsiveness to vaccination with irradiated Trichostrongylus colubriformis were vaccinated and challenged. Duodenal tissue histamine concentrations in both high and low responder lambs were lower at 3 days than at 28 days after challenge. At 3 days after challenge, histamine concentrations were higher in both male and female high responder lambs than in low responder lambs whereas at 28 days concentrations were increased only in high responder females. At 3 days after challenge, histamine concentrations were generally lower in mucus than in tissues, but levels were again higher in mucus from high responder groups. In duodenal tissue at 3 days after challenge, leukotriene C4 and B4 concentrations were similar in high and low responder animals. At the same time, concentrations of both leukotrienes were higher in mucus than in tissues, with high responder female lambs having the highest concentration. It is suggested that increased levels of histamine and leukotrienes in mucus and tissue are associated with larval rejection or exclusion. 相似文献
9.
Lu F Zahid M Saeed M Cavalieri EL Rogan EG 《The Journal of steroid biochemistry and molecular biology》2007,105(1-5):150-158
Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E1) and estradiol (E2) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E1(E2)-3,4-Q], which react with DNA to form predominantly depurinating adducts. This may lead to mutations that initiate cancer. Catechol-O-methyltransferase (COMT) catalyzes an inactivation (protective) pathway for CE. This study investigated the effect of inhibiting COMT activity on the levels of depurinating 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E2 and Ro41-0960, a COMT inhibitor. Estrogen metabolites and depurinating DNA adducts in culture medium were analyzed by HPLC with electrochemical detection. Pre-treatment of cells with TCDD increased E2 metabolism to 4-OHE1(E2) and 4-OCH3E1(E2). Inclusion of Ro41-0960 and E2 in the medium blocked formation of methoxy CE, and depurinating adducts were observed. With Ro41-0960, more adducts were detected in MCF-10F cells exposed to 1 μM E2, whereas without the inhibitor, no increases in adducts were detected with E2 ≤ 10 μM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer. 相似文献
10.
Kazumi Ikeda Miou Toda Kyoko Tanaka Sadako Tokumaru Shosuke Kojo 《Free radical research》1998,28(4):403-410
The cellular localization of lipid hydroperoxides was determined for the first time in mitochondria, microsomes and cytosol of rat liver using a specific method involving chemical derivatization and HPLC. Mitochondria contained the highest level of hydroperoxides. After 6h of intragastric administration of carbon tetrachloride (CCl4) to rats (2 ml/kg body weight), the concentration of lipid hydroperoxides increased significantly in liver mitochondria and cytochrome oxidase activity was inhibited to 35% of the control rats. The mitochondrial content of haem a decreased to 60% of the control at 12 h of CCl4 administration. In vitro reaction of mitochondria with CCl4 caused inactivation of cytochrome oxidase. These observations suggested that cytochrome oxidase and haem a in mitochondria were targets of CCl4. 相似文献
11.
A mixture of tritiated and deuterated gibberellins (GAs) was injected into elongating shoots of Sitka spruce [ Picea sitchensis (Bong.) Carr.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or non-inductive (cool and wet, CW) for flowering. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography–mass spectrometry (GC-MS). Deuterated GA9 was converted to deuterated GA4 , deuterated GA34 , and deuterated GA1 in both treatments. Deuterated GA4 was metabolized to deuterated GA34 and deuterated GA1 in the CW material, but only deuterated GA1 was detected in the HD material. The amount of detected metabolites was higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. GA1 was converted to a polar unidentified metabolite in both treatments, but to a higher degree in the CW treatment. 相似文献
12.
Abstract: Arg0 -Met5 -enkephalin (Arg0 -MEK) was isolated from bovine striatum and purified to homogeneity. The peptide was extracted with trichloroacetic acid, followed by column chromatography successively on Bio-Sil C8 , semipreparative HPLC Radial-Pak C18 , fast protein liquid chromatography (FPLC) Mono S, HPLC Ultrasphere-ODS, Supelco C18 , Lichromsorb C18 , and μBondapak C18 . The peptide content was followed by radioimmunoassay with an antibody against synthetic Met-enkephalin. For each of the six HPLC and FPLC systems, the elution time of the immunoreactive fractions coincided exactly with that of synthetic Arg0 -MEK. The purified peptide showed a highly homogeneous profile in three different analytical HPLC systems. Its retention time and three-dimensional UV spectrum were identical to those of the synthetic Arg0 -MEK. The structure of the purified material was identified by microsequencing as the hexapeptide Arg-Tyr-Gly-Gly-Phe-Met. Ninety percent of the purified peptide was in oxidized form containing equimolar amounts of Met-( R )- and Met-( S )-sulfoxide. The reduced Arg0 -MEK inhibited aminoenkephalinase with a K i of 2.2 µ M , and its sulfoxide analogue inhibited it with a K i of 8.9 µ M . The reduced or oxidized peptide suppressed the electrically induced contraction of rat vas deferens with an ED50 of 5 µ M , and the effect could be reversed by equimolar naloxone. Our data indicate that Arg0 -MEK is an immediate Met-enkephalin precursor and an endogenous inhibitor. 相似文献
13.
Abstract: The amyloid protein (βA4 ) is found in the CNS of patients with Alzheimer's disease; however, the pathogenic role of this protein is not known. In the present study, a peptide fragment of βA4 βA4 25–35; Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-NH2 ), which contains the conserved C-terminal sequence of substance P (X-Gly-Leu-Met-NH2 ), and the neuropeptide substance P (SP) were examined for their ability to modulate nicotine-evoked secretion from cultured bovine adrenal chromaffin cells. Secretion of the released endogenous catecholamines was monitored by electrochemical detection after separation by HPLC. Secretion induced by 10−5 M nicotine was inhibited by SP and βA4 25–35. The IC50 of SP and βA4 25–35 was 3 × 10−6 and 3 × 10−5 M , respectively. SP and βA4 25–35 both protected against nicotinic receptor desensitization. However, βA4 25–35 was ∼ 10-fold less effective than SP in its protective effect. The present work shows that βA4 25–35 can mimic the modulatory actions of SP on the nicotinic response of cultured bovine chromaffin cells, i.e., inhibition of the nicotinic response and protection against nicotinic desensitization. These modulatory actions may be associated with changes in nicotinic receptor levels reported to occur in Alzheimer's disease. 相似文献
14.
A mixture of tritiated and deuterated gibberellin A9 (GA9 ) was injected into elongating shoots of Norway spruce [ Picea abies (L.) Karst.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or noninductive (cool and wet, CW) for flowering. The shoots were divided into needles and shoot stems. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography-mass spectrometry (GC-MS). Deuterated GA9 was converted to deuterated GA4 in both treatments. The major metabolite in the CW-treated material was GA51 . The HD-treated material did not convert GA9 to GA51 , but a cellulase-hydrolysable GA9 -conjugate was formed. The same metabolites were found in the shoot stems, though in smaller amounts. The amounts of detected metabolites were higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. The estimated amounts of endogenous GAs show that the HD-treated material contained higher amounts of GA9 but no differences in the amounts of GA4 were found. 相似文献
15.
A series of cuboidal iron-sulfur clusters [Fe4S3(NO)4(PR3)3]0,1+ (R = Et, Pri, Cy) were synthesized by two routes: reductive desulfurization of [Fe4S4(NO)4] by tertiary phosphines, and substitution of triphenylphosphine in [Fe44S3(NO)4(PPh3)3] by a more basic phosphine. The structures of 3[Fe4S3(NO)4(PEt3)3] · 0.5Et2O, [Fe4S3(NO)4(PEt3)3] [Fe4S3(NO)7] and partially substituted [Fe4S3(NO)4(PPh3)2− (PPri3)] have been determined by X-ray diffraction in order to define the cuboidal Fe4S3 core, previously known only in Roussin's black anion and its reduced form, [Fe4S3(NO)77]1−,2−, and as a part of the iron-molybdenum cofactor of nitrogenase. 相似文献
16.
Abstract Streptomyces antibioticus strain TÜ 99, from which a wide variety of active compounds had been isolated previously, was reinvestigated using an HPLC photoconductivity screening system. Four new compounds were isolated, characterized and their constitutions determined. All four were α,β-unsaturated γ-lactones; the most abundant compound 3 (C10 H16 O4 ), as well as compound 1 (C9 H14 O4 ) had a hydroxy group at C(5) of the lactone ring. The four lactones showed antibiotic activity against Pseudomonas aeruginosa and also a weak inhibition of the chitinase from Serratia marcescens . 相似文献
17.
Antonio Zanotti-Gerosa Euro Solari Luca Giannini Carlo Floriani Nazzareno Re Angiola Chiesi-Villa Corrado Rizzoli 《Inorganica chimica acta》1998,270(1-2):298-311
Lithiation of [p-But-calix[4]-(OMe)2(OH)2] (1), followed by reaction with TiCl3(thf)3 or TiCl4(thf)2, led to the corresponding titanium-calix[4]arene complexes [p-But-calix[4]-(OMe)2(O)2]TiCl] (2) and [p-But-calix[4]-(OMe)2(O)2]TiCl2] (3), respectively. Reaction of 1 with TiCl4(thf)2 results in demethylation of the calix[4]arene and the obtention of [p-But-calix[4]-(OMe)2(O)3]TiCl] (4), whose hydrolysis led to [p-But-calix[4]-(OMe)(OH)3] (6). The preparation of 6 can be carried out as a one-pot synthesis. Both 2 and 4 undergo alkylation reactions using conventional procedures, thus forming surprisingly stable organometallic species, namely [p-But-calix[4]-(OMe)2(O)2Ti(R)] (R = Me (7); CH2Ph (8), p-MeC6H4 (9) and [p-But-calix[4]-(OMe)(O)3Ti(R)] (R = Me (10); CH2Ph (11); p-MeC6H4 (12)). Complexes 7 and 9 undergo a thermal oxidative conversion into 10 and 12, occurring with the demethylation of one of the methoxy groups. A solid state structural property of 9 and 12 has been revealed by X-ray analysis showing a self-assembly of the monomeric units into a columnar polymer, where the p-tolyl substituent at the metal functions as a guest group for an adjacent titanium-calixarene. Reductive alkylation of 3 with Mg(CH2Ph)2 gave 8 instead of forming the corresponding dialkyl derivative. Two synthetic routes have been devised for the synthesis of the Ti(III)-Ti(III) dimer [p-But-calix[4]-(OMe)(O)3Ti]2] (13): the reduction of 4 and the reaction of TiCl3(thf)3 with the lithiated form of 6. A very strong antiferromagnetic coupling is responsible for the peculiar magnetic behavior of 13. The proposed structures have been supported by the X-ray analyses of 4, 9, 12 and 13. 相似文献
18.
T. A. Bazhenova N. S. Emelyanova A. F. Shestakov A. E. Shilov M. Yu. Antipin K. A. Lyssenko 《Inorganica chimica acta》1998,280(1-2):288-294
Reactions of azobenzene have been studied with heteronuclear iron-lithium compounds formed in the reaction of FeCl3 with LiPh, one of the dinitrogen reducing systems of the Vol'pin type: Ph4FeLi4(OEt2)4 (1) and (H2)FePh4Li4(OEt2)4 (2). The structures of the azobenzene complexes formed, (N2Ph2)3FeLi3(OEt2)3 (3) and (N2Ph2)3FeLi2(THF)2 (4), as well as an ether-containing analog of the latter, (N2Ph2)3FeLi2(OEt2)2 (5), were determined by X-ray analysis of single crystals. Coordination of azobenzene at FeLi3 and FeLi2 clusters was shown to result in a sigificant elongation of the NN bond; partial cleavage of this bond on protolysis of the complexes resulted in the formation of hydrazobenzene and aniline. Magnetic susceptibility measurements and theoretic analysis of a similar model complex leads to the conclusion that the iron oxidation state in 3 may be considered between iron (I) and iron(III) (close to iron(I)), whereas in 4 and 5 it is close to iron(II). 相似文献
19.
Masahiko Maekawa Megumu Munakata Takayoshi Kuroda-Sowa Yusaku Suenaga Kunihisa Sugimoto 《Inorganica chimica acta》1999,290(2):256-158
Two novel tetracopper(I) and tetrasilver(I) complexes [Cu4(atdz)6](ClO4)4·2CH3OH (1) and [Ag4(atdz)6](ClO4)4 (2), have been prepared using 2-amino-1,3,4-thiadiazole (atdz), and their crystal structures and properties have been determined. On each tetranuclear complex, two Cu or Ag atoms (M) are bridged by two atdz ligands to form a six-membered N2M2N2 framework. The two N2M2N2 frameworks are in parallel linked by another atdz ligand to provide the tetranuclear structure with a rectangular M4 core. The four Cu or Ag atoms possess a trigonal-square geometry. The two adjacent MM separations are (3.096(1) and 3.412(1) Å) and (3.316(2) and 3.658(2) Å) for 1 and 2, respectively. On both tetranuclear complexes there are two species of hydrogen bonds between the ClO4 − anions and the NH2 group of atdz ligands. It is proposed that the hydrogen bonds are related to the stabilization of the tetranuclear structure during the crystallization process. 相似文献
20.
《植物生态学报》2017,41(11):1208
Methane (CH4) is an important greenhouse gas, and is involved in atmospheric chemical reactions. Aquatic and hydric environments are important sources of atmospheric CH4. Majority of CH4 are transported and released to atmosphere by emerged herbaceous plants and hygrophytes in aquatic and hydric environments. In recent decades, there has been increasing attention on how plants transport CH4. During CH4 transportation processes, several interfaces of CH4 exchange play important roles. First, the tips of lateral roots are primary locations (hotspots) for CH4 entering the root systems and regulate the gross CH4 transportation. Then, the diaphragms in the aerenchyma and the root collar impose great resistances for the overall CH4 transportation processes. In early studies, it was controversial that whether CH4 emission from plants to atmosphere was controlled by stomas or micropores (small cracks and holes in aboveground part of plant except the blade). Recent studies have confirmed the dominant role of micropores for CH4 transportation and emission. The dead and damaged stems are widely considered to have positive effects on CH4 transportation. Diffusion and convection are the two main transporting mechanisms of CH4, with the efficiency of convection being generally higher than that of diffusion. Both biological (e.g. biomass and photosynthesis) and environmental (e.g. light, temperature and humidity) factors regulate the CH4 transportation. Many studies have contributed to understanding the CH4 transportation processes and mechanisms by emerged herbaceous plants and hygrophytes. However, there are still some questions needing further investigations. Issues of consideration may include the operational efficiency in the critical interfaces of CH4 exchange, the plant parts that play a decisive role in the entire CH4 transportation, the underlying roles of diffusion and convection on CH4 interfaces exchanges and entire long distance transports, the combined and coupling effects and mechanisms of biotic and abiotic factors, and the similarities and differences of CH4 transporting processes and mechanisms among plant species. 相似文献