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991.
992.
993.
Gonzalez MA Alvarez Mdel L Pisani GB Bernal CA Roma MG Carrillo MC 《Biological trace element research》2007,116(3):329-348
We have shown that aluminum (Al) induces cholestasis associated with multiple alterations in hepatocellular transporters involved
in bile secretory function, like Mrp2. This work aims to investigate whether these harmful effects are mediated by the oxidative
stress caused by the metal. For this purpose, the capability of the antioxidant agent, vitamin E, to counteract these alterations
was studied in male Wistar rats. Aluminum hydroxide (or saline in controls) was administered ip (27 mg/kg body weight, three
times a week, for 90 d). Vitamin E (600 mg/kg body weight) was coadministered, sc. Al increased lipid peroxidation (+50%)
and decreased hepatic glutation levels (-43%) and the activity of glutation peroxidase (-50%) and catalase (-88%). Vitamin
E counteracted these effects total or partially. Both plasma and hepatic Al levels reached at the end of the treatment were
significantly reduced by vitamin E (-40% and -44%, respectively;p< 0.05). Al increased 4 times the hepatic apoptotic index, and this effect was fully counteracted by vitamin E. Bile flow
was decreased in Al-treated rats (-37%) and restored to normality by vitamin E. The antioxidant normalized the hepatic handling
of the Mrp2 substrates, rose bengal, and dinitrophenyl-S-glutathione, which was causally associated with restoration of Mrp2
expression. Our data indicate that oxidative stress has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage,
and the impairment in liver transport function induced by Al and that vitamin E counteracts these harmful effects not only
by preventing free-radical formation but also by favoring Al disposal. 相似文献
994.
Quiroga AG Cubo L de Blas E Aller P Navarro-Ranninger C 《Journal of inorganic biochemistry》2007,101(1):104-110
In an attempt to design new antitumoral drugs based on transplatin complexes, we determined the experimental conditions for the preparation of trans-[Pt((CH(3))(2)CNOH)((CH(3))(2)CHNH(2))Cl(2)], and solved the crystal structure. The cytotoxicity of the novel complex, the cis counterpart, cisplatin, and a trans complex with aliphatic amines, as well as the capacity of some of these complexes to cause either apoptotic or necrotic cell death, was comparatively examined in NRK-52E rat renal tubular cells and HepG2 human hepatoma cells. The results indicate that the oxime complex with trans geometry, but not the one with cis geometry, causes death by apoptosis, making the complex potentially suitable for therapeutic purposes. However cytotoxicity values are higher in the case of cis geometry than in trans geometry in both tumoral and non-tumoral cell lines. 相似文献
995.
Gabriela Ludwig Lucas M. Aguiar João M. D. Miranda Gustavo M. Teixeira Walfrido K. Svoboda Luciano S. Malanski Marcos M. Shiozawa Carmen L. S. Hilst Italmar T. Navarro Fernando C. Passos 《International journal of primatology》2007,28(1):39-46
Researchers consider predation rates by terrestrial animals to be lower in the case of arboreal primates, particularly among
large-bodied species. We recorded the consumption of black-and-gold howlers (Alouatta caraya) by cougars (Puma concolor) as evidence of predation on an island of the upper Paraná River. We collected and processed fecal samples of the felid in
2004 and 2005. We identified items in the laboratory by comparison with museum specimens. We considered each species in a
fecal sample as a single occurrence. Based on analysis of the cuticle scale pattern, we identified the felid as cougar. Howlers
occurred in 4 out of the 8 fecal samples (40% of the occurrences). In addition to howlers, we also recorded 5 occurrences
of agouti (Dasyprocta azarae; 50%) and a small unidentified sigmodontine rodent (10%). The abundance of howlers and the low forest canopy in a successional
vegetation might have facilitated the predation of the large primates by a primarily terrestrial predator. The versatility
of cougars is corroborated by the consumption of prey species that were abundant in the region and that were available in
different forest strata, such as howlers and agoutis. 相似文献
996.
Lopez del Castillo Lozano M Tâche R Bonnarme P Landaud S 《Journal of microbiological methods》2007,69(1):70-77
A practical adaptation of the methylene blue reaction for hydrogen sulfide quantification was developed to perform microbial selection. Closed plate flasks containing a zinc-agar layer above the liquid microbial culture are proposed as a trap system where the H(2)S can be retained and then quantified by the methylene blue reaction. Using this quantitative method, the ability to produce H(2)S was studied in several cheese-ripening microorganisms. Our aim was to select strains that produce the highest quantities of H(2)S as the main product of L-cysteine catabolism. Thirty seven yeast and bacteria strains were cultivated with or without L-cysteine. The separation between the growth medium and the H(2)S trapping layer displayed good performance: all the studied strains grew efficiently and only negligible loss of H(2)S was observed during culturing. The strains displayed large differences in their H(2)S production capabilities: yeast strains were greater producers of H(2)S than bacteria with production strain-related in both cases. Furthermore, the relationship between H(2)S production and L-cysteine consumption was analyzed, which made it possible for us to select microorganisms with high capacity in L-cysteine degradation. The production of volatile sulfur compounds was also studied and the possible effect of culture pH and metabolic differences between strains are discussed. 相似文献
997.
Viader-Salvadó JM Molina-Torres CA Guerrero-Olazarán M 《Journal of microbiological methods》2007,70(3):479-483
Ziehl–Neelsen acid-fast staining and mycolic acid analysis of concentrated samples and Middlebrook 7H9 cultures were carried out on 127 sputum specimens to evaluate a rapid method for detecting and identifying mycobacteria by analyzing fluorescent derivatives of mycolic acids in concentrated sputum specimens and in Middlebrook 7H9 cultures and compare with mycobacterial detection using Lowenstein–Jensen (LJ) cultures. All samples were classified into five groups according to the number of acid-fast bacilli observed in the smear. The group of samples with 3+ acid-fast bacilli in the smear had the highest number of positive detections of mycolic acids in the concentrated samples and the Middlebrook 7H9 cultures (81.8 and 100%, respectively). The overall percentages of mycolic acid detection for both sample types were 43.2 and 91.3%, respectively. The mycolic acid analysis of the Middlebrook 7H9 cultures had the fewest false negative detections with respect to the LJ cultures. The analysis of fluorescent derivatives of mycolic acids, using HPLC, is useful for concentrated sputum samples with large number of bacilli (3+) and is preferred for Middlebrook 7H9 cultures, even for clinical specimens with a low number of bacilli. Furthermore, with this analytical method, the simultaneous detection and identification of mycobacteria is usually possible. 相似文献
998.
Lacadena J Alvarez-García E Carreras-Sangrà N Herrero-Galán E Alegre-Cebollada J García-Ortega L Oñaderra M Gavilanes JG Martínez del Pozo A 《FEMS microbiology reviews》2007,31(2):212-237
RNase T1 is the best known representative of a large family of ribonucleolytic proteins secreted by fungi, mostly Aspergillus and Penicillium species. Ribotoxins stand out among them by their cytotoxic character. They exert their toxic action by first entering the cells and then cleaving a single phosphodiester bond located within a universally conserved sequence of the large rRNA gene, known as the sarcin-ricin loop. This cleavage leads to inhibition of protein biosynthesis, followed by cellular death by apoptosis. Although no protein receptor has been found for ribotoxins, they preferentially kill cells showing altered membrane permeability, such as those that are infected with virus or transformed. Many steps of the cytotoxic process have been elucidated at the molecular level by means of a variety of methodological approaches and the construction and purification of different mutant versions of these ribotoxins. Ribotoxins have been used for the construction of immunotoxins, because of their cytotoxicity. Besides this activity, Aspf1, a ribotoxin produced by Aspergillus fumigatus, has been shown to be one of the major allergens involved in allergic aspergillosis-related pathologies. Protein engineering and peptide synthesis have been used in order to understand the basis of these pathogenic mechanisms as well as to produce hypoallergenic proteins with potential diagnostic and immunotherapeutic applications. 相似文献
999.
New insights into the unique structure of the F0F1-ATP synthase from the chlamydomonad algae Polytomella sp. and Chlamydomonas reinhardtii 下载免费PDF全文
In this study, we investigate the structure of the mitochondrial F(0)F(1)-ATP synthase of the colorless alga Polytomella sp. with respect to the enzyme of its green close relative Chlamydomonas reinhardtii. It is demonstrated that several unique features of the ATP synthase in C. reinhardtii are also present in Polytomella sp. The alpha- and beta-subunits of the ATP synthase from both algae are highly unusual in that they exhibit extensions at their N- and C-terminal ends, respectively. Several subunits of the Polytomella ATP synthase in the range of 9 to 66 kD have homologs in the green alga but do not have known equivalents as yet in mitochondrial ATP synthases of mammals, plants, or fungi. The largest of these so-called ASA (ATP Synthase-Associated) subunits, ASA1, is shown to be an extrinsic protein. Short heat treatment of isolated Polytomella mitochondria unexpectedly dissociated the otherwise highly stable ATP synthase dimer of 1,600 kD into subcomplexes of 800 and 400 kD, assigned as the ATP synthase monomer and F(1)-ATPase, respectively. Whereas no ASA subunits were found in the F(1)-ATPase, all but two were present in the monomer. ASA6 (12 kD) and ASA9 (9 kD), predicted to be membrane bound, were not detected in the monomer and are thus proposed to be involved in the formation or stabilization of the enzyme. A hypothetical configuration of the Chlamydomonad dimeric ATP synthase portraying its unique features is provided to spur further research on this topic. 相似文献
1000.
Structural organization and a standardized nomenclature for plant endo-1,4-beta-glucanases (cellulases) of glycosyl hydrolase family 9 下载免费PDF全文