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81.
Current methods for the serodiagnosis of sheep fascioliasis show suboptimal sensitivity, specificity, or both. With the aim of developing an improved method, we fractionated native Fasciola hepatica excretory-secretory antigens (ESAs) by size-exclusion FPLC (fast protein liquid chromatography) on a Superdex 75 HR 10/30 column and then tested the serodiagnostic value of the antigens contained in each one of the 4 peaks obtained (peaks I-IV). Serodiagnostic value was assessed using sera from sheep naturally infected with F. hepatica (group A); sera from the individuals of a fluke-free herd (most of which also had other intestinal nematodes, lung nematodes, Moniezia spp., and/or Cysticercus tenuicollis) sera from a fluke-free herd (group B); sera from lambs experimentally infected with 10-40 F. hepatica metacercariae (group C); and sera from uninfected control lambs (group D). Enzyme-linked immunosorbent assay (ELISA) with peak I or II as target antigens (and to a lesser extent with peak III as target) showed reactivity with negative sera, so that it was not possible to establish cutoff values discriminating infected and uninfected animals. In contrast, when peak IV was used as target, a low cutoff value of 0.235 optical density units (mean + 4 SD) discriminated infected and uninfected animals, with 100% sensitivity and 100% specificity. ELISA with peak IV as a target identified infected animals (even animals that had received only 10 metacercariae) within 3-5 wk of infection and subsequently throughout the rest of the 14-wk monitoring period. In Western blotting analysis, again only the antigens contained in peak IV (range 7-40 kDa, under reducing conditions) were specific for diagnosis of infected animals. These results indicate that molecular sieving of F. hepatica ESAs by this procedure is a fast, simple, reproducible way of obtaining antigens useful for serodiagnosis of sheep fascioliasis. 相似文献
82.
We tested for correlations between the geographic, demographic, and temporal distribution of an aquatic insect host and the prevalence of its gut parasites in southwestern Ohio. Trypanosomatids were present in Aquarius remigis collected from all 4 streams surveyed in the watershed. Prevalence declined dramatically from May to July and remained low through the fall. This pattern was consistent over all sites of our study, with no effect of stream, stream site (upstream vs. downstream), or host sex on prevalence. Stage, however, was strongly correlated with prevalence; adults were more likely to be infected than were nymphs. We argue that behavioral differences between the 2 age classes may account for the decline in prevalence; opportunities for transmission are highest in the spring, when mating activities increase adult host contact rates, and decline in the summer, when contact rates decrease. 相似文献
83.
Identification of an equilibrium intermediate in the unfolding process of galectin-1, which retains its carbohydrate-binding specificity 总被引:1,自引:0,他引:1
Iglesias MM Elola MT Martinez V Fink N Wolfenstein-Todel C 《Biochimica et biophysica acta》2003,1648(1-2):164-173
The unfolding process of galectin-1 (Gal-1) in the presence of a denaturing agent was examined using fluorescence and far-UV circular dichroism (CD) spectroscopy determinations, and was found to be completely reversible. The data showed that the transitions of guanidine hydrochloride (GdnHCl)-induced lectin unfolding, in the absence of ligand, were biphasic in nature, clearly showing the existence of at least one stable intermediate. On the other hand, the unfolding in the presence of disaccharide yielded data that could fit very well to a two-state model, indicating a stabilizing effect of the ligand. The folding intermediate was further characterized by size exclusion chromatography, near-UV CD and anilinonaphtalene sulfonate binding, and shown to belong to the molten globule type. Strikingly, this intermediate retained its carbohydrate-binding specificity, as evidenced by the tryptophan fluorescence changes detected upon its interaction with lactose. 相似文献
84.
de la Fuente MT Casanova B Cantero E Hernández del Cerro M Garcia-Marco J Silva A Garcia-Pardo A 《Biochemical and biophysical research communications》2003,311(3):708-712
We recently showed that alpha4beta1 integrin induces B-cell chronic lymphocytic leukemia (B-CLL) cell resistance to fludarabine-induced apoptosis via upregulation of Bcl-xL. We have now studied whether p53 was involved in this response. Cells from five B-CLL patients with wild-type p53 determined by DNA sequencing, or from the EHEB cell line, cultured on the alpha4beta1 ligand H/89 during fludarabine treatment, showed significantly higher viability (P相似文献
85.
Rossoni LV Salaices M Miguel M Briones AM Barker LA Vassallo DV Alonso MJ 《American journal of physiology. Heart and circulatory physiology》2002,283(5):H2110-H2118
The involvement of nitric oxide (NO), prostaglandins, and calcium-dependent potassium channel (K(Ca)) activators on the negative modulation of phenylephrine-induced contractions was evaluated on the isolated aorta and caudal (CAU) artery obtained from rats treated with ouabain for 5 wk to induce hypertension. In ouabain-treated rats, the reactivity to phenylephrine was reduced in the endothelium-intact aorta but not the CAU segments. Endothelial modulation of phenylephrine contraction, as demonstrated by endothelium removal, NO synthase (NOS) inhibition with N(omega)-nitro-L-arginine methyl ester and aminoguanidine, as well as K(Ca) inhibition with tetraethylammonium, was more pronounced in segments from ouabain-treated animals, and here greater effects were seen in the aorta than in CAU. An increased expression of endothelial NOS and neuronal NOS was seen in the aorta after ouabain treatment. In CAU, only endothelial NOS was detected and ouabain treatment did not alter its expression. These results suggest that ouabain-induced hypertension is accompanied by increased NO release derived from endothelial NOS and neuronal NOS and increased release of an endothelial hyperpolarizing factor that presumably opens K(Ca), all of which contribute to the increased negative modulation of the phenylephrine contraction. 相似文献
86.
87.
Thermostable Pyrococcus furiosus DNA ligase catalyzes the synthesis of (di)nucleoside polyphosphates
Günther S Montes M de DA del VM Atencia EA Sillero A 《Extremophiles : life under extreme conditions》2002,6(1):45-50
DNA ligase from the hyperthermophilic marine archaeon Pyrococcus furiosus (Pfu DNA ligase) synthesizes adenosine 5'-tetraphosphate (p4A) and dinucleoside polyphosphates by displacement of the adenosine 5'-monophosphate (AMP) from the Pfu DNA ligase-AMP (E-AMP) complex with tripolyphosphate (P3), nucleoside triphosphates (NTP), or nucleoside diphosphates (NDP). The experiments were performed in the presence of 1-2 microM [alpha-32P]ATP and millimolar concentrations of NTP or NDP. Relative rates of synthesis (%) of the following adenosine(5')tetraphospho(5')nucleosides (Ap4N) were observed: Ap4guanosine (Ap4G) (from GTP, 100); Ap4deoxythymidine (Ap4dT) (from dTTP, 95); Ap4xanthosine (Ap4X) (from XTP, 94); Ap4deoxycytidine (Ap4dC) (from dCTP, 64); Ap4cytidine (Ap4C) (from CTP, 60); Ap4deoxyguanosine (Ap4dG) (from dGTP, 58); Ap4uridine (Ap4U) (from UTP, <3). The relative rate of synthesis (%) of adenosine(5')triphospho(5')nucleosides (Ap3N) were: Ap3guanosine (Ap3G) (from GDP, 100); Ap3xanthosine (Ap3X) (from XDP, 110); Ap3cytidine (Ap3C) (from CDP, 42); Ap3adenosine (Ap3A) (from ADP, <1). In general, the rate of synthesis of Ap4N was double that of the corresponding Ap3N. The enzyme presented optimum activity at a pH value of 7.2-7.5, in the presence of 4 mM Mg2+, and at 70 degrees C. The apparent Km values for ATP and GTP in the synthesis of Ap4G were about 0.001 and 0.4mM, respectively, lower values than those described for other DNA or RNA ligases. Pfu DNA ligase is used in the ligase chain reaction (LCR) and some of the reactions here reported [in particular the synthesis of Ap4adenosine (Ap4A)] could take place during the course of that reaction. 相似文献
88.
Pérez-Vizcaíno F López-López JG Santiago R Cogolludo A Zaragozá-Arnáez F Moreno L Alonso MJ Salaices M Tamargo J 《American journal of physiology. Lung cellular and molecular physiology》2002,283(4):L839-L848
The maturation in the vasodilator response to nitric oxide (NO) in isolated intrapulmonary arteries was analyzed in newborns and 15- to 20-day-old piglets. The vasodilator responses to NO gas but not to the NO donor sodium nitroprusside increased with age. The inhibitory effects of the superoxide dismutase inhibitor diethyldithiocarbamate and xanthine oxidase plus hypoxanthine and the potentiation induced by superoxide dismutase and MnCl(2) of NO-induced vasodilatation were similar in the two age groups. Diphenyleneiodonium (NADPH oxidase inhibitor) potentiated the response to NO, and this effect was more pronounced in the older animals. The nonselective cyclooxygenase inhibitors indomethacin and meclofenamate and the preferential cyclooxygenase-1 inhibitor aspirin augmented NO-induced relaxation specifically in newborns, whereas the selective cycloxygenase-2 inhibitor NS-398 had no effect. The expressions of alpha-actin, cycloxygenase-1, and cycloxygenase-2 proteins were similar, whereas Cu,Zn-superoxide dismutase decreased with age. Therefore, the present data suggest that the maturational increase in the vasodilatation of NO in the pulmonary arteries during the first days of extrauterine life involves a cycloxygenase-dependent inhibition of neonatal NO activity. 相似文献
89.
Heavy metals and arsenic uptake by wild vegetation in the Guadiamar river area after the toxic spill of the Aznalcóllar mine 总被引:4,自引:0,他引:4
Del Río M Font R Almela C Vélez D Montoro R De Haro Bailón A 《Journal of biotechnology》2002,98(1):125-137
On 25 April 1998, approximately 4.5 hm(3) of pyritic sludge, containing 5000 mg of As kg(-1) among other pollutants, was spilled into the Agrio and Guadiamar rivers and the surrounding agricultural areas (Aznalcóllar, Seville, Southern Spain). Many trace metals such as Pb, Cu, Zn, Cd, Tl, Sb and As reached the Do?ana National Park, the largest wetland area in Europe, affecting soils, different plant and animal species. In order to recuperate the affected lands by employing plants capable of accumulating high levels of contaminants in shoots, periodical field surveys have been made to identify the metal-tolerant species that are spontaneously growing in the polluted soils, and are able to uptake one or various of the contaminants. Among the 99 different plant species studied, Anchusa azurea, Beta vulgaris, Chamaemelum fuscatum, Convolvulus arvensis, Cynodon dactylon, Diplotaxis virgata, Erodium aethiopicum, Lavatera cretica, Malva nicaeensis, Silybum marianum and, above all, Amaranthus blitoides highlight as the most promising to be used in the remediation of the affected area. 相似文献
90.
Effect of pre-adsorbed proteins on attachment,proliferation, and function of endothelial cells 总被引:2,自引:0,他引:2
As certain proteins control cell adhesion, it has been hoped that cell transplantation and tissue engineering could be augmented by pre-adsorption of specific proteins to biological or synthetic surfaces. The questions that remain, however, are whether such proteins can affect cell production as well as adhesion, and if so, whether in a protein-specific manner. We examined the adhesion and the biochemical secretion of bovine aortic endothelial cells (BAEC) on tissue culture polystyrene (TCPS) discs coated with fibronectin (Fn), laminin (Ln), or gelatin. The three coating proteins nonspecifically promote sub-confluent and post-confluent endothelial cell production of total protein up to 2.5-fold of the reference value. Total soluble glycosaminoglycan (GAG) production slightly increased with the different coatings only at low cell density. In contrast, Ln and Fn, not gelatin, drastically enhanced post-confluent BAEC production of prostaglandin (PGI2). However, antibody-blockage of the alpha5 integrin, constituent of the Fn receptor in BAEC, appeared to inhibit the upregulation of PGI2 production observed on Fn-coated surfaces. The results indicate that the cell adhesion mediators used as coating agents dictate cell biological production as well as adhesion and proliferation. 相似文献