187 resultados para Materials and process characterization


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This is a case report of enteric protothecosis caused by Prototheca zopfii in an eight-year-old male mixed breed dog with a history of chronic bloody diarrhea, loss of appetite and weight loss. Algae were isolated from rectal scrapings in defibrinated sheep blood agar and dextrose Sabouraud agar. Cytological evaluation showed the presence of globular and cylindrical organisms with a defined capsule and variable number of endospores, characteristic of the genus Prototheca, in the rectum of the animal. Scanning electron microscopy of P. zopfii strains at different development stages confirmed the diagnosis of algal infection. Molecular identification using a conserved 18S rDNA gene sequence determined that the strain belonged to genotype 2. This report describes success on treatment of canine protothecosis, diagnosed based on clinical, cytological, microbiological, scanning electron microscopy and genotypical findings. (c) 2009 Elsevier Ltd. All rights reserved.

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Bats are main reservoirs for Lyssavirus worldwide, which is an important public health issue because it constitutes one of the big challenges in rabies control. Yet, little is known about how the virus is maintained among bats, and the epidemiological relationships remain poorly understood. The aim of the present study was to investigate the distribution of the rabies virus (RABV) in bat tissues and organs and to genetically characterize virus isolates from naturally infected non-hematophagous bats. The heminested reverse transcriptase polymerase chain reaction (hnRT-PCR) and sequencing using primers to the nucleoprotein coding gene were performed. The results showed a dissemination of the RABV in different tissues and organs, particularly in the salivary glands, tongue, lungs, kidneys, bladder, intestine and feces, suggesting other possible forms of RABV elimination and the possibility of transmission among these animals. The phylogenetic analysis confirmed that different variants of RABV are maintained by non-hematophagous bats in nature and have similar tissue distribution irrespective of bat species and phylogenetic characterization. (C) 2012 Elsevier B.V. All rights reserved.

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The aim of this study was to evaluate the effects of different litter materials on litter compaction, broiler feathering and the incidence of carcass lesions. In the experiment, 3240 one-day-old Ross® chicks were selected by sex and distributed according to a completely randomized experimental design in a 2 x 6 factorial arrangement (two sex and six litter materials). The following litter materials were used: wood shavings, rice husks, chopped Napier grass, 50% sugar cane bagasse plus 50% wood shavings, 50% sugar cane bagasse plus 50% rice husks, and pure sugar cane bagasse. Litter compaction was weekly assessed using a penetrometer. on days 21, 35 and 42 of the experimental period, feathering on the back and legs was scored according to a 0 - 10 scale. on day 42, birds were slaughtered and the presence of bruises, scratches and footpad lesions was recorded. Litter material had no effect on bird feathering. Carcass lesions (scratches, bruises and footpad lesions) were influenced by the litter material evaluated. Birds reared on sugarcane bagasse and chopped Napier grass presented more scratches, bruises and footpad lesions than the others. Dermatitis was more evident in birds reared on sugarcane bagasse, chopped Napier grass and the combination of litter materials. It was found that males presented higher incidence of dermatitis and footpad lesions than females. Each litter material presented different compaction degrees, which increased along the experimental period. Sugarcane bagasse, chopped Napier grass and the combination of bedding materials presented the highest degree of compaction, compared with wood shavings and rice husks.

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The objective of the present study was to characterize ovogones, primary oocytes and preantral follicles of buffalo fetus in different ages of gestation. For this, 29 fetuses were collected from a slaughterhouse (Frigol, Brazil) and crown-rump lengths were measured to estimate the fetal age (0-3, 4-6, 7-10 months of gestation). The ovaries were removed and ovarian tissue was processed for classic histology and transmission eletron microscopy examination. The structural evaluation demonstrated that in the first period of the gestation (0-3 months) the buffalo fetus showed ovogones (in mitotic division) and in some cases, the primary oocytes surrounded by somatic cells. In the second period (4-6 months), it was verified that the preantral follicles were completely formed. In the last period (70 month to the end of gestation) the ovaries contained a large amount of preantral follicles, and in some fetuses, antral follicles were observed. The ultrastructural analysis of the ovogones, primary oocytes and preantral follicles showed that these cells have few organelles and the quantity of mitochondria, endoplasmatic reticulum and apparatus Golgi complex is increased as the germinative cells passing from one stage to another.

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There are many reports of cryptosporidial infection in ostriches, but none with molecular characterization of the isolates. A study was undertaken for the characterization of a Brazilian Cryptosporidium sp. ostrich isolate by using molecular phylogenetic analysis of fragments of the 18S ribosonial DNA. heat-shock Protein (lisp) 70 coding gene, and actin coding gene. Biological studies were accomplished by the experimental inoculation of chickens via oral or intratracheal routes with fresh ostrich Cryptosporidium sp. oocysts. Molecular analysis of nuceotide sequences of the 3 genes by using neighbor-joining and parsimony methods grouped the ostrich isolate as a sister taxon of Crypiosporidium badeyi and showed that the os(rich isolate is genetically distinct from all other known Cryptosporidium species or genotypes. None of the inoculated chickens developed infection as determined by mucosal smears. histology, and fecal screening for oocysts. Although biological and molecular Studies indicate that the ostrich Cryptosporidium is a new species, further Studies regarding morphological. biological, and molecular characteristics of other ostrich isolates are required to confirm the species status of the ostrich Cryprosporidium.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Objectives: This in situ study evaluated the effect of an erosive challenge on different restorative materials and on enamel restored with these materials, as well as the ability of these materials to protect the adjacent enamel against erosion.Methods: Ten volunteers wore palatal devices with eight bovine enamel blocks, randomly selected and distributed into two vertical rows, corresponding to the following groups: GI/GV, resin-modified glass ionomer; GII/GVI, conventional glass ionomer; GIII/GVII, composite resin; GIV/GVIII, amalgam. one row (corresponding to groups I-IV) was immersed in a cola drink and the other row (corresponding to groups V-VIII) was subjected to saliva only. The palatal device was continuously worn for 7 days and only half of the appliance (groups I-IV) was immersed in the soft drink (Coca-Cola (R), 150 mL) for 5 min, three times a day. The study variables comprised the wear (profilometry, mu m) and the percentage of surface microhardness change (%SMHC). Data were tested for significant differences by two-way ANOVA and Tukey's tests (p < 0.05).Results: Considering the restorative materials, for %SMHC and wear, there were no differences among the materials and between the saliva and the erosive challenge. For enamel analyses, the erosive challenge promoted a higher wear and %SMHC of the enamel than did the saliva. There were no significant differences in wear and %SMHC of the enamel adjacent to the different restorative materials.Conclusion: This research data suggest that there is little %SMHC and wear of the studied restorative materials and none of them had a preventive effect against erosion on adjacent enamel, which showed a pronounced wear. (c) 2007 Elsevier Ltd. All rights reserved.

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This in vitro study evaluated the effect of erosive pH cycling on the percentage of surface micro-hardness change (%SMHC) and wear of different restorative materials and bovine enamel restored with these materials. Eighty enamel specimens were randomly divided into eight groups according to the restorative materials and immersion media used: GI/GV-resin-modifled glass-ionomer, GII/GVI-conventional glass-ionomer, GIII/GVII-resin composite and GIV/GVIII-amalgam. Over a period of seven days, groups GI to GIV were immersed in a cola drink (ERO) for 5 minutes, 3x/day and kept in artificial saliva between erosive cycles. Groups GV to GVIII were immersed in artificial saliva (SAL) throughout the entire experimental period (control). Data were tested for significant differences using ANOVA and Tukey's tests (p < 0.05). For %SMHC, considering the restorative materials, no significant differences were detected among the materials and immersion media. Mean wear was higher for the resin modified glass ionomer cement when compared to conventional cement, but those materials did not significantly differ from the others. For enamel analyses, erosive pH cycling promoted higher wear and %SMHC compared to saliva. There were no significant differences in wear and %SMHC of enamel around the different restorative materials, regardless of the distance from the restorative material (50, 150 or 300 mu m). In conclusion, there were only subtle differences among the materials, and these differences were not able to protect the surrounding enamel from erosion.

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BnSP-7, a Lys49 myotoxic phospholipase A, homologue from Bothrops neuwiedi pauloensis venom, was structurally and functionally characterized. Several biological activities were assayed and compared with those of the chemically modified toxin involving specific amino acid residues, the cDNA produced from the total RNA by RT-PCR contained approximately 400 bp which codified its 121 amino acid residues with a calculated pi and molecular weight of 8.9 and 13,727, respectively. Its amino acid sequence showed strong similarities with several Lys49 phospholipase A, homologues from other Bothrops sp, venoms. By affinity chromatography and gel diffusion, it was demonstrated that heparin formed a complex with BnSP-7, held at least in part by electrostatic interactions. BnSP-7 displayed bactericidal activity and promoted the blockage of the neuromuscular contraction of the chick, biventer cervicis muscle. In addition to its in vivo myotoxic and edema-inducing activity, it disrupted artificial membranes, Both BnSP-7 and the crude venom released creatine kinase from the mouse gastrocnemius muscle and induced the development of a dose-dependent edema. His, Tyr, and Lys residues of the toxin were chemically modified by 4-bromophhenacyl bromide (BPB), 2-nitrobenzenesulfonyl fluoride (NBSF), and acetic anhydride (AA), respectively. Cleavage of its N-terminal octapeptide was achieved with cyanogen bromide (CNBr), the bactericidal action of BnSP-7 on Escherichia coli was almost completely abolished by acetylation or cleavage of the N-terminal octapeptide, the neuromuscular effect induced by BnSP-7 was completely inhibited by heparin, BPB, acetylation, and CNBr treatment. The creatine kinase releasing and edema-inducing effects were partially inhibited by heparin or modification by BPB and almost completely abolished by acetylation or cleavage of the N-terminal octapeptide, the rupture of liposomes by BnSP-7 and crude venom was dose and temperature dependent. Incubation of BnSP-7 with EDTA did not change this effect, suggesting a Ca2+-independent membrane lytic activity. BnSP-7 cross-reacted with antibodies raised against B. moojeni (MjTX-II), B. jararacussu (BthTX-I), and B. asper (Basp-II) myotoxins as well as against the C-terminal peptide (residues 115-129) from Basp-II. (C) 2000 Academic Press.

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BjussuMP-II is an acidic low molecular weight metalloprotease (Mr similar to 24,000 and pI similar to 6.5), isolated from Bothrops jararacussu snake venom. The chromatographic profile in RP-HPLC and its N-terminal sequence confirmed its high purity level. Its complete cDNA was obtained by RT-PCR and the 615 bp codified for a mature protein of 205 amino acid residues. The multiple alignment of its deduced amino acid sequence and those of other snake venom metalloproteases showed a high structural similarity, mainly among class P-I proteases. The molecular modeling analysis of BjussuMP-II showed also conserved structural features with other SVMPs. BjussuMP-II did not induce hemorrhage, myotoxicity and lethality, but displayed dose-dependent proteolytic activity on fibrinogen, collagen, fibrin, casein and gelatin, keeping stable at different pHs, temperatures and presence of several divalent ions. BjussuMP-II did not show any clotting or anticoagulant activity on human citrated plasma, in contrast to its inhibitory effects on platelet aggregation. The aspects broached, in this work, provide data on the relationship between structure and function, in order to better understand the effects elicited by snake venom metalloproteases. (c) 2007 Elsevier B.V. All rights reserved.

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An acidic (pI similar to 4.5) phospholipase A(2) (BthA-I-PLA(2)) was isolated from Bothrops jararacussu snake venom by ion-exchange chromatography on a CM-Sepharose column followed by reverse phase chromatography on an RP-HPLC C-18 column. It is an similar to13.7 kDa single chain Asp49 PLA(2) with approximately 122 amino acid residues, 7 disulfide bridges, and the following N-terminal sequence: 'SLWQFGKMINYVMJGESGVLQYLSYGCYCGLGGQGQPTDATDRCCFVHDCC(51). Crystals of this acidic protein diffracted beyond 2.0 Angstrom resolution. These crystals are monoclinic and have unit cell dimensions of a = 33.9, b = 63.8, c = 49.1 Angstrom, and beta = 104.0degrees. Although not myotoxic, cytotoxic, or lethal, the protein was catalytically 3-4 tithes more active than BthTX-II, a basic D49 myotoxic PLA(2) from the same venom and other Bothrops venoms. Although it showed no toxic activity, it was able to induce time-independent edema, this activity being inhibited by EDTA. In addition, BthA-I-PLA(2) caused a hypotensive response in the rat and inhibited platelet aggregation, Catalytic, antiplatelet and other activities were abolished by chemical modification with 4-bromophenacyl bromide, which is known to covalently bind to His48 of the catalytic site. Antibodies raised against crude B. jararacussu venom recognized this acidic PLA(2), while anti-Asp49-BthTX-II recognized it weakly and anti-Lys49-BthTX-I showed the least cross-reaction. These data confirm that myotoxicity does not necessarily correlate with catalytic activity in native PLA(2) homologues and that either of these two activities may exist alone. BthA-I-PLA(2), in addition to representing a relevant molecular model of catalytic activity, is also a promising hypotensive agent and platelet aggregation inhibitor for further studies. (C) 2002 Elsevier B.V. All rights reserved.