Structure of a calcium-independent phospholipase-like myotoxic protein from Bothrops asper venom

Myotoxin II, a myotoxic calcium-independent phospholipase-like protein isolated from the venom of Bothrops asper, possesses no detectable phospholipase activity. The crystal structure has been determined and refined at 2.8 Angstrom to an R factor of 16.5% (F>3 sigma) with excellent stereochemistry. Amino-acid differences between catalytically active phospholipases and myotoxin LI in the Ca2+-binding region, specifically the substitutions Tyr28-->Asn, Gly32-->Leu and Asp49-->Lys, result in an altered local conformation. The key difference is that the epsilon-amino group of Lys49 fills the site normally occupied by the calcium ion in catalytically active phospholipases. In contrast to the homologous monomeric Lys49 variant from Agkistrodon piscivorus piscivorus, myotoxin II is present as a dimer both in solution and in the crystalline state. The two molecules in the asymmetric unit are related by a nearly perfect twofold axis, yet the dimer is radically different from the dimer formed by the phospholipase from Crotalus atrox. Whereas in C. atrox the dimer interface occludes the active sites, in myotoxin II they are exposed to solvent.

Effect of cooling procedure on final denture base adaptation

Well-fitted dentures prevent hyperplasic lesions, provide chewing efficiency and promote patient's comfort. Several factors may affect final adaptation of dentures, as the type of the acrylic resin, the flask cooling procedure and the water uptake. This investigation evaluated the effect of water storage and two different cooling procedures [bench cooling (BC) for 2 h; running water (RW) at 20 degreesC for 45 min] on the final adaptation of denture bases. A heat-cured acrylic resin (CL, Classico, Classico Artigos Odontologicos) and two microwave-cured acrylic resins [Acron MC, (AC) GC Dent. Ind. Corp.; Onda Cryl (OC), Classico Artigos Odontologicos] were used to make the bases. Adaptation was assessed by measuring the weight of an intervening layer of silicone impression material between the base and the master die. Data was submitted to ANOVA and Tukey's test (0.05). The following means were found: (BC) CL=0.72 +/- 0.03 a; AC=0.70 +/- 0.03 b; OC=0.76 +/- 0.04 c//(RW) CL= 1.00 +/- 0.11 a; AC=1.00 +/- 0.12 a; OC=0.95 +/- 0.10 a. Different labels join groups that are not statistically different (P > 0.05). Comparisons are made among groups submitted to the same cooling procedure (BC or RW). The conclusions are: interaction of type of material and cooling procedure had a statistically significant effect on the final adaptation of the denture bases (P < 0.05); water storage was not detected as a source of variance (P > 0.05) on the final adaptation.

A rapid procedure for the isolation of the Lys-49 myotoxin II from Bothrops moojeni (caissaca) venom: Biochemical characterization, crystallization, myotoxic and edematogenic activity

A, M. Soares, V, M, Rodrigues, M. I. Homsi-Brandeburgo, M. H. Toyama, F, R, Lombardi, K. Arni and J. R, Giglio. A rapid procedure for the isolation of the Lys-49 myotoxin II from Bothrops moojeni (caissaca) venom: Biochemical characterization, crystallization, myotoxic and edematogenic activity. Toxicon 36, 503-514, 1998.-Bothrops moojeni snake venom was fractionated on a CM-Sepharose column which was previously equilibrated with 0.05 M ammonium bicarbonate buffer at pH 8.0 and subsequently eluted with an ammonium bicarbonate concentration gradient from 0.05 to 0.5 M at constant pH (8.0) and temperature (25 degrees C). The fraction which eluted last (M-VI) showed, after direct lyophilization, a single band by polyacrylamide gel electrophoresis (PAGE) and SDS-PAGE, indicating an approximate M,. of 14 000 and 77 000, in the presence and absence of dithiothreitol, respectively. Its amino acid composition revealed a high level of hydrophobic and basic amino acids as well as 13 half-cystine residues. Its isoelectric point and extinction coefficient (E-1.0cm(1.0mg/ml) at 278 nm and pH 7.0) were 8.2 and 1.170, respectively. M-VI was devoid of phospholipase A(2) (PLA(2)) activity on egg yolk, as well as of hemorrhagic, anticoagulant and coagulant activities, but could induce drastic necrosis on skeletal muscle fibres as well as rapid and transient edema on the rat paw. Its N-terminal sequence: SLFELGKMILQETGKNPAKSYGVYGCNCGVGGRGKPKDATDRCCYVHKCCYK.... revealed high homology with other Lys 49 PLA(2)-like myotoxins from other bothropic venoms. Orthorhombic crystals of M-VI? which diffracted to a maximal resolution of 1.6 Angstrom. were obtained and indicated the presence of a dimer in the asymmetrical unit. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

Detection of Listeria sp in meat and meat products using TECRA Listeria visual immunoassay and biocontrol visual immunoprecipitate assay for Listeria immunoassays and a cultural procedure

The routine methods for detecting Listeria sp. in foods are time consuming and involve using selective enrichments and plating on agars. In this study, the presence of Listeria sp. in 120 meat and meat product samples was investigated by two rapid immunoassays (TECRA Listeria Visual Immunoassay [VIA] and BioControl Visual Immunoprecipitate Assay [VIP] for Listeria) and a cultural procedure. The cultural method of detecting Listeria sp. followed Canada's Health Protection Branch Method, and the rapid tests followed the manufacturers' instructions. The agreement between the cultural and the rapid tests was established at a confidence limit of 95%. Seventy-nine samples (65.8%) were Listeria sp. positive in at least one of the three tests. There was no statistically significant difference between the cultural procedure and any of the rapid immunoassays. The agreement rates between the VIA and the cultural method and between the VIP and the cultural method were 87 and 84%, respectively. Both tests - the VIA and VIP - proved to be rapid, efficient and easy to perform.

SPT-T: test procedure and applications

Ranzini (1988) proposed the Standard Penetration Test with torque measurement (SPT-T) and some geotechnical engineers in Brazil have been using it since 1991. This paper presents the state of the art on SPT-T testing, emphasizing what is already established as common knowledge in Brazilian engineering practice, besides a suggestion for test procedure, including equipment and practical aspects. In addition, the study of the shape of the torque versus rotation-degree angle curve obtained by an electric torquemeter used in several SPT-T tests carried out on six experimental research sites in the southeast region of Brazil is discussed here. Four different methods to predict pile capacity based on SPT-T test results are briefly presented and a comparison with load tests carried out on different types of piles, on those six experimental research sites, is presented.

Generalizing the soldering procedure

We start this work by revisiting the problem of the soldering of two chiral Schwinger models of opposite chiralities. We verify that, different from what one can conclude from the current literature, the usual sum of these models is, in fact, gauge invariant and corresponds to a composite model, where the component models are the vector and axial Schwinger models. As a consequence, we reinterpret this formalism as a kind of degree of freedom reduction mechanism. This result has led us to discover a second soldering possibility giving rise to the axial Schwinger model. This new result is seemingly rather general. We explore it here in the soldering of two Maxwell-Chern-Simons theories with different masses.

A SIMPLE AND FAST PROCEDURE TO GROW BAT FIBROBLASTS FROM LUNG BIOPSIES FOR CYTOGENETIC STUDIES

A fast, simple, and inexpensive procedure to establish fibroblast culture from bat lungs is presented. Explants plated following mechanical disaggregation provide good quality preparations for cytogenetics studies in about one week. Cultures established with this procedure may also be used for other biological studies.

A fast microwave-assisted, acid-vapor, steam-cleaning procedure for autosampler cups

A new and fast procedure is proposed for cleaning autosampler cups using acid-vapor steam-cleaning with a miniaturized assembly in a microwave-heated sealed Teflon vessel. A glass cactus-shaped holder was made to support six polyethylene autosampler cups (volume, 2.0 mt) inside a 100 mt microwave vessel. Regent-grade nitric acid was added to the vessels, and the system was heated in a microwave oven for 5 min at 300 W. Chromium was determined by graphite-furnace atomic-absorption spectrophotometry. The blank values were lower with cleaned cups compared to untreated cups (i.e., as received from supplier). The quantification limits, estimated from detection limits established with Milli-Q water, were 0.66 and 0.95 mu g Cr L-1 for cleaned and untreated auto-sampler cups, respectively. (C) 1998 Elsevier B.V. B.V. All rights reserved.

A COMBINATION OF METHOTRIMEPRAZINE, MIDAZOLAM AND GUAIPHENESIN, WITH AND WITHOUT KETAMINE, IN AN ANESTHETIC PROCEDURE FOR HORSES

A combination of 0.5 mg/kg of methotrimeprazine, 0.1 mg/kg of midazolam and 100 mg/kg of a 10 per cent guaiphenesin solution was investigated for the induction of recumbency in 15 horses; the addition of 1.6 mg/kg of ketamine was also evaluated in 15 horses and anaesthesia was maintained with halothane in oxygen. The horses became recumbent quickly and smoothly and they recovered quietly, with little ataxia. Tachycardia occurred after induction, but no other changes from pre-operative values were observed until halothane in oxygen had been given, when hypothermia, hypotension, bradypnoea, hyperoxaemia, respiratory acidosis and decreased respiratory minute volume developed. Horses given ketamine in addition to methotrimeprazine, midazolam and guaiphenesin were easier to intubate and recovered more quickly than horses receiving only methotrimeprazine, midazolam and guaiphenesin.

AN IMPROVED ENRICHMENT PROCEDURE FOR THE ISOLATION OF YERSINIA-ENTEROCOLITICA AND RELATED SPECIES FROM MILK

A new enrichment procedure is proposed to improve the isolation of Yersinia enterocolitica and related species from milk. This procedure uses tryptic soy broth plus Polymyxin (5 IU/ml) and Novobiocin (10 mug/ml) - TSPN broth - incubated at 18-degrees-C for 3 d. Using raw milk and pasteurized milk inoculated with Yersinia strains, the efficiency of this procedure was compared to that of SB broth (sorbitol bile salts broth) incubated at 4-degrees-C for up to 21 d. Despite of the presence of antibiotics in TSPN broth, there were difficulties in recovering Yersinia organisms. Nevertheless, TSPN broth incubated at 18-degrees-C for 3 d showed better efficiency than that other method. In pasteurized milk samples, TSPN medium at 18-degrees-C for 3 d gave better results than the SB broth at 4-degrees-C for 7 d, showing that the proposed procedure is the preferable one due to the shorter period of incubation.

Procedure optimization of silicate rocks dissolution in open vessels for ICP-AES analysis.

The main variables found on procedure of the dissolution silicate rocks using acid dissolution in teflon open vessel for analysis of micro elements by ICP-AES has been determined. The results obtained for some samples showed strong dependence of the rock mineralogical composition, then it was recommended an alkaline fusion step after acid dissolution. The decomposition procedure use 20 mi of an acid mixture of HF:HNO3 in the proportion 3:1 for a fraction of 250 mg pulverized sample. The recommended temperatures were 60 degrees C for attack and 90 degrees C for acid volatilization. The fusion step with 50 mg LiBO2 at 1000 degrees C may be used if non-attacked residue is observed in the solution. The whole time was 6 h per sample. Nine types os silicate rocks that show mineralogical and chemical different compositions were chosen for obtaining the optimization of the variables. The elements used were Ce, Y, Yb and Zr. In addition, ultrassonic nebulization has been used. The percentual standard deviations obtained for five determinations were 0.7 and 1.4 for triplicate samples. The mineralogical and textural information from the petrographical analysis of the samples indicated the need of increasing the fusion step on the optimized procedure.

A procedure to estimate parameters of a line segment taking into account its representation through pi circuits: Theoretical development

The objective of this paper is to show an alternative methodology to estimate per unit length parameters of a line segment of a transmission line. With this methodology the line segment parameters can be obtained starting from the phase currents and -voltages in receiving and sending end of the line segment. If the line segment is represented as being one or more pi circuits whose frequency dependent parameters are considered lumped, its impedance and admittance can be easily expressed as functions of the currents and voltages at the sending and receiving end. Because we are supposing that voltages and currents at the sending and receiving end of the tine segment (in frequency domain) are known, it is possible to obtains its impedance and admittance and consequently its per unit length longitudinal and transversal parameters. The procedure will be applied to estimate the longitudinal and transversal parameters of a small segment of a single-phase line that is already built.