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991.
Parra EA Carvajal G Peña Y Lizarazo J 《Biomédica : revista del Instituto Nacional de Salud》2005,25(4):439-40, 565-7
992.
993.
Anaya AL Macías-Rubalcava M Cruz-Ortega R García-Santana C Sánchez-Monterrubio PN Hernández-Bautista BE Mata R 《Phytochemistry》2005,66(4):487-494
Aqueous leachates and a CHCl3-MeOH (1:1) extract of roots of Stauranthus perforatus showed a significant phytotoxic effect on Amaranthus hypochondriacus and Echinochloa crus-galli. Bioassay-directed fractionation of the active organic extract led to the isolation and characterization of ten secondary metabolites, which included two pyranocoumarins [xanthyletin (1) and 3-(1',1'-dimethylallyl)-xanthyletin (2)], four furanocoumarins [chalepensin (3), ammirin (4), chalepin (5) and 2'-isopropyl-psoralene (6)], two lignans [asarinin (7) and fargesin (8)], one sesquiterpene [4,5-epoxi-beta-caryophyllene (9)], and one alkamide [pellitorine (10)]. From these compounds, 2'-isopropyl-psoralene (6) or anhydromarmesin, is reported for the first time as a natural product, whereas compounds 4-10 are now reported as being present in S. perforatus. Metabolites 1, 3-5 and 10 caused significant inhibition of radicle growth of A. hypochondriacus and E. crus-galli. Furthermore, in a greenhouse experiment the decomposition of the leaves and roots in the soil had a significant inhibitory effect on the growth of weeds. The allelopathic action of the decomposition of roots was evident up to the sixth week of the experiment. The effect of leaves was comparable to that of DPCA (dimethyl tetrachloroterephthalate), a commercial herbicide. Finally different concentrations of Stauranthus root powder were combined with maize kernels and used to feed corn weevil. The treatments resulted in high mortality of this insect. 相似文献
994.
Highly ordered lipids adsorbed or grafted on surfaces are known to provide protection and lubrication custom engineered surfaces. We have used atomic force microscopy (AFM) to measure adhesion and frictional properties of the outermost surfaces of a variety of human hairs with the aim of both understanding the role of 18-methyleicosanoic acid (18-MEA), an unusual branched-chain fatty acid covalently bound to the cuticle surface, and investigating how treatments or the ethnic origin affect this layer. Results show that an unmodified silicon nitride AFM tip is able to detect changes at the hair surface that can be related to the absence or presence of this layer due to treatment conditions and in particular that this monolayer has a lubricant effect. 相似文献
995.
Echevarría-Machado I Sánchez-Cach LA Hernández-Zepeda C Rivera-Madrid R Moreno-Valenzuela OA 《Molecular biotechnology》2005,31(2):129-135
A protocol is described for rapid DNA isolation from Malvaceae plant species and different tissues of Bixaceae that contain
large amounts of polysaccharides, polyphenols, and pigments that interfere with DNA extractions. The method is a modification
of Dellaporta et al. The current protocol is simple, and no phenolchloroform extraction, ethanol, or isopropranol precipitation
is required. The method is based in the incubation of soluble DNA with silica, mix in batch during the extraction. The procedure
can be completed in 2 h and many samples can be processed at the same time. DNA of excellent quality was recovered and used
for polymerase chain reaction (PCR) amplification, restriction enzyme digestion, and Southern blot analysis. The method was
used with healthy Bixa orellana and virus-infected Malvaceae plants. 相似文献
996.
Taylor ML Ruíz-Palacios GM del Rocío Reyes-Montes M Rodríguez-Arellanes G Carreto-Binaghi LE Duarte-Escalante E Hernández-Ramírez A Pérez A Suárez-Alvarez RO Roldán-Aragón YA Romero-Martínez R Sahaza-Cardona JH Sifuentes-Osornio J Soto-Ramírez LE Peña-Sandoval GR 《FEMS immunology and medical microbiology》2005,45(3):435-441
Three isolates of Histoplasma capsulatum were identified from mice lung, liver, and spleen inoculated with soil samples of the X hotel's ornamental potted plants that had been fertilized with organic material known as compost. The presence of H. capsulatum in the original compost was detected using the dot-enzyme-linked immunosorbent assay. Nested-PCR, using a specific protein Hcp100 coding gene sequence, confirmed the fungal identification associated with an unusual histoplasmosis outbreak in Acapulco. Although, diversity between the H. capsulatum isolate from the hotel and some clinical isolates from Guerrero (positive controls) was observed using random amplification of polymorphic DNA based-PCR, sequence analyses of H-anti and ole fragment genes revealed a high homology (92-99%) between them. 相似文献
997.
Letelier ME Lepe AM Faúndez M Salazar J Marín R Aracena P Speisky H 《Chemico-biological interactions》2005,151(2):71-82
It is generally accepted that copper toxicity is a consequence of the generation of reactive oxygen species (ROS) by copper ions via Fenton or Haber-Weiss reactions. Copper ions display high affinity for thiol and amino groups occurring in proteins. Thus, specialized proteins containing clusters of these groups transport and store copper ions, hampering their potential toxicity. This mechanism, however, may be overwhelmed under copper overloading conditions, in which copper ions may bind to thiol groups occurring in proteins non-related to copper metabolism. In this study, we propose that indiscriminate copper binding may lead to damaging consequences to protein structure, modifying their biological functions. Therefore, we treated liver subcellular membrane fractions, including microsomes, with Cu2+ ions either alone or in the presence of ascorbate (Cu2+/ascorbate); we then assayed both copper-binding to membranes, and microsomal cytochrome P450 oxidative system and GSH-transferase activities. All assayed sub-cellular membrane fractions treated with Cu2+ alone displayed Cu2+-binding, which was significantly increased in the presence of Zn2+, Hg2+, Cd2+, Ag+1 and As3+. Treatment of microsomes with Cu2+ in the μM range decreased the microsomal thiol content; in the presence of ascorbate, Cu2+ added in the nM concentrations range induced a significant microsomal lipoperoxidation; noteworthy, increasing Cu2+ concentration to ≥50 μM led to non-detectable lipoperoxidation levels. On the other hand, μM Cu2+ led to the inhibition of the enzymatic activities tested to the same extent in either presence or absence of ascorbate. We discuss the possible significance of indiscriminate copper binding to thiol proteins as a possible mechanism underlying copper-induced toxicity. 相似文献
998.
Hernández-Pacheco G Murguía LE Rodríguez-Pérez JM Fragoso JM Pérez-Vielma N Martínez-Rodríguez N Granados J Vargas-Alarcón G 《Human biology; an international record of research》2005,77(3):385-391
Matrix gamma-carboxyglutamic acid protein (MGP) genotypes (G-7A and T-138C) were determined in 266 individuals from three Mexican populations. Mexicans showed increased frequencies of the G-7A G allele and the G7-A GG genotype compared to Europeans. For the T-138C genotype, we found differences among the Mexicans. This study could help to define the significance of MGP polymorphisms as genetic markers in Amerindian populations. 相似文献
999.
Hernández HM Figueredo M Garrido N Sánchez L Sarracent J 《International journal for parasitology》2005,35(13):1333-1337
Trichomonosis, caused by the protozoan parasite Trichomonas vaginalis, is one of the most frequent sexually transmitted diseases and is widely spread in all continents. Trichomonas vaginalis as well as other protozoan organisms have high levels of proteolitic activity mainly of the cysteine-proteinase type. This activity is necessary for recognition and adhesion of the parasite to the superficial epithelial cells of the host. In the present study, we show that intranasal immunisation with a 62 kDa cysteine-proteinase purified from T. vaginalis excretion-secretion products in combination with cholera toxin or with synthetic oligodeoxynucleotides (ODN) that contain unmethylated CpG motifs (CpG-ODN) elicits 62kDa specific IgG and IgA in vaginal lavage fluid and specific IgG in serum. This immunisation protocol resulted in enhanced elimination of parasites following intravaginal challenge of BALB/c mice. 相似文献
1000.