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81.
Cavasini CE De Mattos LC Alves RT Couto AA Calvosa VS Domingos CR Castilho L Rossit AR Machado RL 《Human biology; an international record of research》2006,78(2):215-219
We compared the serological phenotypic frequencies of ABO, MNSs, and Duffy in 417 blood donors and 309 malaria patients from four Brazilian Amazon areas. Our results suggest no correlation between ABO phenotype and malaria infection in all areas studied. We observed significant correlation between the S +s +, S +s -, and S -s + phenotypes and malaria infection in three areas. Some of the Duffy phenotypes showed significant correlation between donors and malaria patients in different areas. These data are an additional contribution to the establishment of differential host susceptibility to malaria. 相似文献
82.
During maturation, procaspase-3 is cleaved at D175, which resides in a linker that connects the large and small subunits. The intersubunit linker also connects two active site loops that rearrange following cleavage and, in part, form the so-called loop bundle. As a result of chain cleavage, new hydrogen bonds and van der Waals contacts form among three active site loops. The new interactions are predicted to stabilize the active site. One unresolved issue is the extent to which the loop bundle residues also stabilize the procaspase active site. We examined the effects of replacing four loop bundle residues (E167, D169, E173, and Y203) on the biochemical and structural properties of the (pro)caspase. We show that replacing the residues affects the activity of the procaspase as well as the mature caspase, with D169A and E167A replacements having the largest effects. Replacement of D169 prevents caspase-3 autoactivation, and its cleavage at D175 no longer leads to an active enzyme. In addition, the E173A mutation, when coupled to a second mutation in the procaspase, D175A, may alter the substrate specificity of the procaspase. The mutations affected the active site environment as assessed by changes in fluorescence emission, accessibility to quencher, and cleavage by either trypsin or V8 proteases. High-resolution X-ray crystallographic structures of E167A, D173A, and Y203F caspases show that changes in the active site environment may be due to the increased flexibility of several residues in the N-terminus of the small subunit. Overall, the results show that these residues are important for stabilizing the procaspase active site as well as that of the mature caspase. 相似文献
83.
Rondon E Brasileiro-Santos MS Moreira ED Rondon MU Mattos KC Coelho MA Silva GJ Brum PC Fiorino P Irigoyen MC Krieger EM Middlekauff HR Negrão CE 《American journal of physiology. Heart and circulatory physiology》2006,291(6):H2801-H2806
Exercise training improves arterial baroreflex control in heart failure (HF) rabbits. However, the mechanisms involved in the amelioration of baroreflex control are unknown. We tested the hypothesis that exercise training would increase the afferent aortic depressor nerve activity (AODN) sensitivity in ischemic-induced HF rats. Twenty ischemic-induced HF rats were divided into trained (n = 11) and untrained (n = 9) groups. Nine normal control rats were also studied. Power spectral analysis of pulse interval, systolic blood pressure, renal sympathetic nerve activity (RSNA), and AODN were analyzed by means of autoregressive parametric spectral and cross-spectral algorithms. Spontaneous baroreflex sensitivity of heart rate (HR) and RSNA were analyzed during spontaneous variation of systolic blood pressure. Left ventricular end-diastolic pressure was higher in HF rats compared with that in the normal control group (P = 0.0001). Trained HF rats had a peak oxygen uptake higher than untrained rats and similar to normal controls (P = 0.01). Trained HF rats had lower low-frequency [1.8 +/- 0.2 vs. 14.6 +/- 3 normalized units (nu), P = 0.0003] and higher high-frequency (97.9 +/- 0.2 vs. 85.0 +/- 3 nu, P = 0.0005) components of pulse interval than untrained rats. Trained HF rats had higher spontaneous baroreceptor sensitivity of HR (1.19 +/- 0.2 vs. 0.51 +/- 0.1 ms/mmHg, P = 0.003) and RSNA [2.69 +/- 0.4 vs. 1.29 +/- 0.3 arbitrary units (au)/mmHg, P = 0.04] than untrained rats. In HF rats, exercise training increased spontaneous AODN sensitivity toward normal levels (trained HF rats, 1,791 +/- 215; untrained HF rats, 1,150 +/- 158; and normal control rats, 2,064 +/- 327 au/mmHg, P = 0.05). In conclusion, exercise training improves AODN sensitivity in HF rats. 相似文献
84.
Marcelo Mattos Cavallari Rafaela Campostrini Forzza Elizabeth Ann Veasey Maria Imaculada Zucchi Giancarlo Conde Xavier Oliveira 《Biodiversity and Conservation》2006,15(14):4357-4373
Encholirium is a Brazilian genus of Bromeliaceae that occurs exclusively in rocky landscapes. This work aimed to generate basic information for the conservation of three Encholirium species that are endemic to the rocky mountains of Cadeia do Espinhaço, employing population genetic analyses. E. pedicellatum and E. biflorum have only one very small population each, both occurring in unprotected, private land sites, being critically endangered. E. subsecundum is more widespread, and some of its populations dwell in protected areas. Five Random Amplified Polymorphic DNA (RAPD) primers generated approximately 60 polymorphic bands for each species. This technique demonstrated the presence of a single RAPD profile for every individual sampled (except for one clone found in E. biflorum). High levels of genetic variability were not expected, due to the clonal habit of the plants and small size of the populations. Populations of E. biflorum and E. pedicellatum presented, respectively, 16.06% (Φ st = 0.16, p<0.001) and 8.44% (Φ st = 0.08, p<0.001) of the total genetic diversity attributable to genetic differences among groups within the populations. In E. subsecundum, 14.52% (Φ st = 0.15, p<0.001) of the total genetic diversity was found among populations. Estimates of the Shannon’s Diversity Index provided similar results. These results are valuable for the development of conservation strategies. 相似文献
85.
The multiple solvent crystal structures (MSCS) method uses organic solvents to map the surfaces of proteins. It identifies binding sites and allows for a more thorough examination of protein plasticity and hydration than could be achieved by a single structure. The crystal structures of bovine pancreatic ribonuclease A (RNAse A) soaked in the following organic solvents are presented: 50% dioxane, 50% dimethylformamide, 70% dimethylsulfoxide, 70% 1,6‐hexanediol, 70% isopropanol, 50% R,S,R‐bisfuran alcohol, 70% t‐butanol, 50% trifluoroethanol, or 1.0M trimethylamine‐N‐oxide. This set of structures is compared with four sets of crystal structures of RNAse A from the protein data bank (PDB) and with the solution NMR structure to assess the validity of previously untested assumptions associated with MSCS analysis. Plasticity from MSCS is the same as from PDB structures obtained in the same crystal form and deviates only at crystal contacts when compared to structures from a diverse set of crystal environments. Furthermore, there is a good correlation between plasticity as observed by MSCS and the dynamic regions seen by NMR. Conserved water binding sites are identified by MSCS to be those that are conserved in the sets of structures taken from the PDB. Comparison of the MSCS structures with inhibitor‐bound crystal structures of RNAse A reveals that the organic solvent molecules identify key interactions made by inhibitor molecules, highlighting ligand binding hot‐spots in the active site. The present work firmly establishes the relevance of information obtained by MSCS. Proteins 2009. © 2009 Wiley‐Liss, Inc. 相似文献
86.
The steady-state internal redox state (NADH/NAD) reflects the external redox state and is correlated with catabolic adaptation in Escherichia coli 总被引:4,自引:0,他引:4 下载免费PDF全文
de Graef MR Alexeeva S Snoep JL Teixeira de Mattos MJ 《Journal of bacteriology》1999,181(8):2351-2357
Escherichia coli MC4100 was grown in anaerobic glucose-limited chemostat cultures, either in the presence of an electron acceptor (fumarate, nitrate, or oxygen) or fully fermentatively. The steady-state NADH/NAD ratio depended on the nature of the electron acceptor. Anaerobically, the ratio was highest, and it decreased progressively with increasing midpoint potential of the electron acceptor. Similarly, decreasing the dissolved oxygen tension resulted in an increased NADH/NAD ratio. As pyruvate catabolism is a major switch point between fermentative and respiratory behavior, the fluxes through the different pyruvate-consuming enzymes were calculated. Although pyruvate formate lyase (PFL) is inactivated by oxygen, it was inferred that the in vivo activity of the enzyme occurred at low dissolved oxygen tensions (DOT = 1%). A simultaneous flux from pyruvate through both PFL and the pyruvate dehydrogenase complex (PDHc) was observed. In anaerobic cultures with fumarate or nitrate as an electron acceptor, a significant flux through the PDHc was calculated on the basis of the redox balance, the measured products, and the known biochemistry. This result calls into question the common assumption that the complex cannot be active under these conditions. In vitro activity measurements of PDHc showed that the cellular content of the enzyme varied with the internal redox state and revealed an activity for dissolved oxygen tension of below 1%. Whereas Western blots showed that the E3 subunit of PDHc (dihydrolipoamide dehydrogenase) did not vary to a large extent under the conditions tested, the E2 subunit (dihydrolipoamide acetyltransferase) amount followed the trend that was found for the in vitro PDHc activity. From this it is concluded that regulation of the PDHc is exerted at the E1/E2 operon (aceEF). We propose that the external redox state (measured as the midpoint potentials of those terminal acceptors with which the cell has sufficient capacity to react) is reflected by the internal redox state. The latter may subsequently govern both the expression and the activity of the two pyruvate-catabolizing enzymes. 相似文献
87.
88.
Thiengo SC Mattos AC Boaventura MF Fernandez MA 《Memórias do Instituto Oswaldo Cruz》2004,99(3):275-280
In this paper, the forth of a series dealing with the survey of freshwater gastropods of the state of Rio de Janeiro, the results of collections carried out in the Sul Fluminense Mesoregion from 2000 to 2002 are presented and revealed the occurrence of 18 species: Antillorbis nordestensis; Biomphalaria glabrata; Biomphalaria peregrina; Biomphalaria straminea; Biomphalaria tenagophila; Drepanotrema anatinum; Drepanotrema cimex; Drepanotrema lucidum; Ferrissia sp.; Gundlachia ticaga; Gundlachia sp.; Heleobia sp.; Lymnaea columella; Melanoides tuberculatus; Physa acuta; Physa marmorata; Pomacea sordida and Pomacea sp. As to the snail hosts of Schistosoma mansoni the most frequent species was B. tenagophila, found in all municipalities surveyed, except Parati. Besides new records the present study extends the distribution of B. peregrina and B. straminea in the state. No specimens were found harbouring larval forms of S. mansoni although different kinds of cercariae had been observed. An account about the current schistosomiasis transmission sites in this Mesoregion is presented as well. 相似文献
89.
Santos CB Hjalgrim H Carneiro FR Ribeiro M Boy RT Pimentel MM 《Annales de génétique》2003,46(1):53-55
The concurrence of fragile X and Klinefelter syndromes would be expected occasionally. Therefore, the analysis of the literature showed that the concurrence of both conditions was found at least 16 times. Among them, only seven cases were analyzed for the parental origin of the extra chromosome X, suggesting that the maternal nondisjunction was preferentially inherited. We present the third patient with the concurrence of fragile X and Klinefelter syndromes, in which the parental origin of the supernumerary chromosome X was paternal. This finding reinforces that the parent-of-origin predisposition of the concurrence of the fragile X and Klinefelter syndromes is a pure coincidence. 相似文献
90.
Room temperature crystal structures of crosslinked H-Ras bound to GMPPNP were solved in 50% 2,2,2-trifluoroethanol, 60% 1,6-hexanediol, and 50% isopropanol. The disordered switch II region of Ras is ordered in the presence of 2,2,2-trifluoroethanol or 1,6-hexanediol. The overall backbone conformation of switch II in these organic solvents is the same as in the Ras-GMPPNP complexes with RalGDS, PI(3) kinase, and RasGAP, indicating a biologically relevant form. Key polar interactions that stabilize the ordered switch are enhanced in the presence of hydrophobic cosolvents. These results suggest that hydrophobic solvents can be used in general to order short biologically relevant segments of disordered regions in protein crystals by favoring H-bonding interactions between atoms that are highly solvated and mobile in aqueous solution. 相似文献