915 resultados para Eustathius, Archbishop of Thessalonica, d. ca. 1194.


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Sphingomyelinases D (SMases D) from Loxosceles spider venom are the principal toxins responsible for the manifestation of dermonecrosis, intravascular hemolysis, and acute renal failure, which can result in death. These enzymes catalyze the hydrolysis of sphingomyelin, resulting in the formation of ceramide 1-phosphate and choline or the hydrolysis of lysophosphatidyl choline, generating the lipid mediator lysophosphatidic acid. This report represents the first crystal structure of a member of the sphingomyelinase D family from Loxosceles laeta (SMase I), which has been determined at 1.75-angstrom resolution using the quick cryo-soaking technique and phases obtained from a single iodine derivative and data collected from a conventional rotating anode x-ray source. SMase I folds as an (alpha/beta)(8) barrel, the interfacial and catalytic sites encompass hydrophobic loops and a negatively charged surface. Substrate binding and/or the transition state are stabilized by a Mg2+ ion, which is coordinated by Glu(32), Asp(34), Asp(91), and solvent molecules. In the proposed acid base catalytic mechanism, His(12) and His(47) play key roles and are supported by a network of hydrogen bonds between Asp(34), Asp(52), Trp(230), Asp(233), and Asn(252).

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We study the order parameter for mixed-symmetry states involving a major d(x2-y2) state and various minor s-wave states (s, s(xy), and Sx2+y2) for different filling and temperature for mixing angles 0 and pi /2. We employ a two-dimensional tight-binding model incorporating second-neighbor hopping for tetragonal and orthorhombic lattice. There is mixing for the symmetric s state both on tetragonal and orthorhombic lattice. The s(xy) state mixes with the d(x2-y2) state only on orthorhombic lattice. The s(x2+y2) state never mixes with the d(x2-y2) state. The temperature dependence of the order parameters is also studied. (C) 2001 Elsevier B.V. B.V. All rights reserved.

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We report on a measurement of the B-d(0) mixing frequency and the calibration of an opposite-side flavor tagger in the D0 experiment. Various properties associated with the b quark on the opposite side of the reconstructed B meson are combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance is tested with data, using a large sample of reconstructed semileptonic B ->mu(DX)-X-0 and B ->mu(DX)-X-* decays, corresponding to an integrated luminosity of approximately 1 fb(-1). The events are divided into groups depending on the value of the combined tagging variable, and an independent analysis is performed in each group. Combining the results of these analyses, the overall effective tagging power is found to be epsilon D-2=(2.48 +/- 0.21(-0.06)(+0.08))%. The measured B-d(0) mixing frequency Delta m(d)=0.506 +/- 0.020(stat)+/- 0.016(syst) ps(-1) is in good agreement with the world average value.

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Considering the static solutions of the D-dimensional nonlinear Schrodinger equation with trap and attractive two-body interactions, the existence of stable solutions is limited to a maximum critical number of particles, when D greater than or equal to 2. In case D = 2, we compare the variational approach with the exact numerical calculations. We show that, the addition of a positive three-body interaction allows stable solutions beyond the critical number. In this case, we also introduce a dynamical analysis of the conditions for the collapse. (C) 2000 Published by Elsevier B.V. B.V. All rights reserved.

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We study the (D) over barN interaction at low energies with a quark model inspired in the QCD Hamiltonian in Coulomb gauge. The model Hamiltonian incorporates a confining Coulomb potential extracted from a self-consistent quasiparticle method for the gluon degrees of freedom, and transverse-gluon hyperfine interaction consistent with a finite gluon propagator in the infrared. Initially a constituent-quark mass function is obtained by solving a gap equation and baryon and meson bound-states are obtained in Fock space using a variational calculation. Next, having obtained the constituent-quark masses and the hadron waves functions, an effective meson-nucleon interaction is derived from a quark-interchange mechanism. This leads to a short range meson-baryon interaction and to describe long-distance physics vector- and scalar-meson exchanges described by effective Lagrangians are incorporated. The derived effective (D) over barN potential is used in a Lippmann-Schwinger equation to obtain phase shifts. The results are compared with a recent similar calculation using the nonrelativistic quark model.

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In tropical poultry-producing countries, poultry houses usually have little environmental control. This study investigated the effect of dietary vitamin D on the incidence of leg abnormalities of a fast-growing broiler strain reared under harsh conditions. In this study, 300 one-day-old male broilers were distributed in two treatments with three replicates of 50 birds each. One group was fed a placebo and the other group was fed 25-hydroxycholecalciferol (25-OH-D3) in a soluble form. The environmental variables were weekly recorded during until birds were 49 days old. Birds were weekly gait scored, and their walking speed and vertical force while walking were assessed. Post-mortem examination was performed and skeletal lesions were assessed. Control birds presented more leg problems than those that ingested 25-OH-D3. These results suggest that dietary vitamin D is effective in decreasing the severity of lameness by reducing tibial dyschondroplasia and other leg abnormalities.

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The D allozyme of placental alkaline phosphatase (PLAP) displays enzymatic properties at variance with those of the common PLAP allozymes. We have deduced the amino acid sequence of the PLAP D allele by PCR cloning of its gene, ALPP Two coding substitutions were found in comparison With the cDNA of the common PLAP F allele, i.e., 692C>G and 1352A>G, which translate into a P209R and E429G substitution. A single nucleotide primer extension (SNuPE) assay was developed using PCR primers that enable the amplification of a 1.9 kb PLAP fragment. Extension primers were then used on this PCR fragment to detect the 692C>G and 1352A>G substitution. The SNuPE assay on these two nucleotide substitutions enabled us to distinguish the PLAP F and D alleles from the PLAP S/I alleles. Functional studies on the D allozyme were made possible by constructing and expressing a PLAP D cDNA, i.e., [Arg209, Gly429] PLAP, into wildtype Chinese hamster ovary cells. We determined the k(cat) and K-m, of the PLAP S, F. and D allozymes using the non,physiological substrate p-nitrophenylphosphate at an optimal pH (9.8) as well as two physiological substrates, i.e., pyridoxal-5'-phosphate and inorganic pyrophosphate at physiological pH (7.5). We found that the biochemical properties of the D allozyme of PLAP are significantly different from those of the common PLAP allozymes. These biochemical findings suggest that a suboptimal enzymatic function by the PLAP D allozyme may be the basis for the apparent negative selective pressure of the PLAP D allele. The development of the SNuPE assay will enable us to test the hypothesis that the PLAP D allele is subjected to intrauterine selection by examining genomic DNA from statistically informative population samples. Hum Mutat 19:258-267, 2002. (C) 2002 Wiley-Liss, Inc.

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An approximate expression is constructed for the energy of an anharmonic potential with centrifugal barrier. In order to obtain such an analytical expression, the quasi-exact solvability is used and then a fitting of these exact solutions is done.

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Cathepsin D, a lysosomal aspartic protease, has been purified from porcine liver using a combination of pepstatin-A agarose and Affi-Gel Blue affinity chromatography, followed by size-exclusion chromatography. The purified protein consists of two polypeptide chains of 15 and 30 kDa, and has an isoelectric point of 6.8. Porcine liver cathepsin D has maximum activity at pH 2.5-3.0 as determined by its activity against hemoglobin, with a K-cat of 14.3 s(-1) and a k(cat)/K-M of 2.70 x 10(6) s(-1) M-1 as determined by the hydrolysis of a fluorogenic peptide substrate.

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Actiaomycin-D (actD) binds to natural DNA at two different classes of binding sites, weak and strong. The affinity for these sites is highly dependent on DNA se(sequence and solution conditions, and the interaction appears to be purely entropic driven Although the entropic character of this reaction has been attributed to the release of water molecules upon drug to DNA complex formation, the mechanism by which hydration regulates actD binding and discrimination between different classes of binding sites on natural DNA is still unknown. In this work, we investigate the role of hydration on this reaction using the osmotic stress method. We skew that the decrease of solution water activity, due to the addition of sucrose, glycerol ethylene glycol, and betaine, favors drug binding to the strong binding sites on DNA by increasing both the apparent binding affinity Delta G, and the number of DNA base pairs apparently occupied by the bound drug n(bp/actD). These binding parameters vary linearly with the logarithm of the molar fraction of water in solution log(X-w), which indicates the contribution of water binding to the energetic of the reaction. It is demonstrated that the hydration change measured upon binding increases proportionally to the apparent size of the binding site n(bp/uctD). This indicates that n(bp/actD) measured from the Scatchard plod is a measure of the size of the DNA molecule changing conformation due to ligand binding. We also find that the contribution of DNA deformation, gauged by n(bp/act) to the total free energy of binding Delta G, is given by Delta G = Delta G(local) + n(bp/actD) x delta G(DNA), where Delta G(local), = -8020 +/- 51 cal/mol of actD bound and delta G(DNa) = -24.1 +/- 1.7cal/mol of base pair at 25 degrees C. We interpret Delta G(local), as the energetic contribution due to the direct interactions of actD with the actual tetranucleotide binding site, and it n(bp/actB) X delta G(DNA) as that due to change inconformation, induced by binding, of it n(bp/actD) DNA base pairs flanking the local site. This interpretation is supported by the agreement found between the value of delta G(DNA) and the torsional free energy change measured independently. We conclude suggesting an allosteric model for ligand binding to DNA, such that the increase in binding affinity is achieved by increasing the relaxation of the unfavorable free energy of binding storage at the local site through a larger number of DNA base pairs. The new aspect on this model is that the size of the complex is not fixed but determined by solutions conditions, such as water activity, which modulate the energetic barrier to change helix conformation. These results may suggest that long-range allosteric transitions of duplex DNA are involved in the inhibition of RNA synthesis by actD, and more generally, in the regulation of transcription. (C) 2000 John Wiley & Sons, Inc.

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The slope of the distance-time relationship from maximal 200 and 400 in bouts (S(200-400)) has been increasingly employed for setting training intensities in swimming. However, physiological and mechanical responses at this speed are poorly understood. Thus, this study investigated blood lactate, heart rate (HR), stroke rate (SR), stroke length (SL) and RPE responses to an interval swimming set at S(200-400) in trained swimmers. In a 50-m pool, twelve athletes (16.5 +/- 1.2 yr, 176 +/- 7 cm, 68.4 +/- 5.4 kg, and 7.8 +/- 2.5% body fat) performed maximal 200 and 400 m crawl trials for S(200-400) determination (1.28 +/- 0.05 m/s). Thereafter, swimmers were instructed to perform 5 x 400 in at this speed with 1.5 min rest between repetitions. Three athletes Could not complete the set (exhaustion at 21.0 +/- 3.1 min). For the remaining swimmers (total set duration = 32.0 +/- 1.3 min) significant increases) (p < 0.05) in blood lactate (5.7 +/- 0.8-7.9 +/- 2.4 mmol/l), SR (29.6 +/- 3.2-32.1 +/- 4.1 cycles/min), HR (169 +/- 11-181 +/- 8 bpm) and RPE (13.3 +/- 1.6-16.3 +/- 2.6) were observed through the IS. Conversely, SL decreased significantly (p < 0.05) from the first to the fifth repetition (2.48 +/- 0.22-2.31 +/- 0.24 m/cycle). These results suggest that interval swimming at S(200-400) represents an intense physiological, mechanical and perceptual stimulus that can be sustained for a prolonged period by most athletes. (C) 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

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We examined the variation in mitochondrial DNA by sequencing the D-loop region in wild and domestic (large-white breed) pigs, in hybrids between domestic and wild pigs, and in Monteiro pigs. A D-loop fragment of approximately 330 bp was amplified by PCR. Sequencing of DNA amplicons identified haplotypes previously described as European and Asian types. Monteiro pigs and wild pigs had European haplotypes and domestic pigs had both European and Asian haplotypes. ©FUNPEC-RP.

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In this work, (Ca 1-xCu x)TiO 3 crystals with (x = 0, 0.01 and 0.02), labeled as CTO, CCTO1 and CCTO2, were synthesized by the microwave-hydrothermal method at 140°C for 32 min. XRD patterns (Fig. 1), Rietveld refinement and FT-Raman spectroscopy indicated that these crystals present orthorhombic structure Pbnm. Micro-Raman and XANES spectra suggested that the substitution of Ca by Cu in A-site promoted a displacement of the [TiO6]-[TiO6] clusters adjacent from its symmetric center, which leads distortions on the [CaO 12] clusters neighboring and consequently cause the strains into the CaTiO3 lattice. FE-SEM images showed that these crystals have an irregular shape as cube like probably indicating an Ostwald-ripening and self-assemble as dominant mechanisms to crystals growth. The powders presented an intense PL blue-emission.

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This study was aimed to evaluate the influence of vitamin D (VD) deficiency on cardiac metabolism, morphology, and function. Thus, we investigated the relationship of these changes with the length of the nutrient restriction. Male weanling Wistar rats were allocated into 4 groups: C2 (n=24), animals were fed an AIN-93G diet with 1000 IU VD/kg of chow and were kept under fluorescent light for 2 months; D2 (n=22), animals were fed a VD-deficient AIN-93G diet and were kept under incandescent light for 2 months; C4 (n=21) animals were kept in the same conditions of C2 for 4 months; and D4 (n=23) animals were kept in the same conditions of D2 for 4 months. Biochemical analyses showed lower β-hydroxyacyl coenzyme-A dehydrogenase activity and higher lactate dehydrogenase activity in VD-deficient animals. Furthermore, VD deficiency was related to increased cytokines release, oxidative stress, apoptosis, and fibrosis. Echocardiographic data showed left ventricular hypertrophy and lower fractional shortening and ejection fraction in VD-deficient animals. Difference became evident in the lactate dehydrogenase activity, left ventricular weight, right ventricle weight, and left ventricular mass after 4 months of VD deficiency. Our data indicate that VD deficiency is associated with energetic metabolic changes, cardiac inflammation, oxidative stress, fibrosis and apoptosis, cardiac hypertrophy, left chambers alterations, and systolic dysfunction. Furthermore, length of the restriction influenced these cardiac changes.