Rossemberg Cardoso Barbosa

Infecção experimental por Trypanosoma vivax em ovinos

This paper has the objective to report clinical signs, hematologic changes, and macroscopic and microscopic alterations in sheep infected experimentally with Trypanosoma vivax, isolated from an outbreak in cattle in the semiarid region of the state of Paraiba, northeastern Brazil. Four Santa Ines sheep were inoculated intravenously with 1ml of blood containing 1.85x105 trypomastigotes. Other 4 sheep were used as control. The presence of trypanosomes in the blood and the temperature were recorded daily during the first 30 days and fortnightly from day 31 to day 90 after infection. Also fortnightly, the sheep were weighed and blood samples were obtained for hematological analysis. One inoculated sheep died 75 days after inoculation. The other 3 inoculated and the 4 control sheep were killed 90 days after the beginning of the experiment. T. vivax was observed constantly in the blood of the inoculated sheep from 4-15 days after inoculation. From day 16 to day 30 the parasitemia was lower and irregular. No trypanosomes were observed in the blood after 30 days of infection. A positive linear correlation [Y=0.027x + 38.515, R2=0.944 (P<0.05)] was found between the number of trypanosomes in the blood and body temperature. Significant differences were observed in body weight between inoculated and non-inoculated sheep from day 30 to day 90 after the experiment. From day 30 to day 90 after inoculation trypanosomes were absent or only in low numbers in the blood, and the animals showed anemia and leucopenia. Gross alterations were pale carcasses, enlarged lymph nodes and spleen, and augmented liquid in the peritoneal and pericardiac cavities. Multifocal lymphocytic myocarditis was observed histologically. It is concluded that the isolate is pathogenic to sheep. It is suggested that the semiarid region, where the outbreak occurred, is non-endemic (marginal) for trypanosomosis, and that the disease may occur if the parasite is introduced through vectors.

Intoxicação por nitratos e nitritos em bovinos por ingestão de Echinochloa polystachya (capim-mandante) e Pennisetum purpureum (capim-elefante) no sertão da Paraíba

Three outbreaks of nitrate poisoning are reported from the semiarid region of the state of Paraiba, northeastern Brazil. One outbreak caused by Echinochloa polystachya (capim-mandante) and two others caused by Pennisetum purpureum (capim-elefante) occurred at the end of the dry season, after the first rains. In one of the outbreaks caused by Pennisetum purpureum part of the pasture had been fertilized with cattle manure. Five out of 11 cattle died on one farm, 27 out of 81 on another, and 3 out of 9 on a third one. Clinical signs were anorexia, respiratory distress, teeth grinding, depression or hyperexitability, tremors, abdominal contractions, salivation, nasal discharge, uncoordinated gait, cyanosis, and finally recumbency. Nitrates and nitrites in the blood of affected cattle and pastures were determined by the diphenylamine test. It is suggested that the main reason for nitrate accumulation in the grasses was the prolonged draught followed by rain. In one of the outbreaks caused by Pennisetum purpureum, another reason was probably the fertilization of the soil with cattle manure.

Biocompatibility of Dental Restorative Materials

Biocompatibility is the ability of a material appropriate trigger a biological response, when applied to the body, without causing a chronic inflammatory reaction, foreign body reaction or toxicity, is related to the interaction of the cell / biomaterial. A few materials, if any, are completely inert from the physiological point of view since, most of the components with a variety of potential toxic or irritating. In addition, chemical reactions during cure of the material may also produce undesirable effects. In order to increase knowledge about the characteristics and properties of materials and their interaction with the biological environment, this study aimed, through literature review, guide and inform didactically professionals and academics on the importance of biocompatibility of restorative materials more direct use in dental practice: silver amalgam, composite resins and glass ionomer cements. It was concluded that, among the restorative materials studied, the glass ionomer cement showed the best characteristics and properties that confirm its biocompatibility in dental practice.

Ionically Crosslinked Chitosan Membranes Used as Drug Carriers for Cancer Therapy Application

The aim of this paper was to prepare, by the freeze-drying method, ionically crosslinked chitosan membranes with different contents of pentasodium tripolyphosphate (TPP) and loaded with 1,4-naphthoquinone (NQ14) drug, in order to evaluate how the physical crosslinking affects NQ14 release from chitosan membranes for cancer therapy application. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), swelling degree, and through in vitro drug release and cytotoxicity studies. According to the results, the molecular structure, porosity and hydrophilicity of the chitosan membranes were affected by TPP concentration and, consequently, the NQ14 drug release behavior from the membranes was also affected. The release of NQ14 from crosslinked chitosan membranes decreased when the cross-linker TPP quantity increased. Thus, depending on the TPP amount, the crosslinked chitosan membranes would be a potential delivery system to control the release of NQ14 for cancer therapy application. Lastly, the inhibitory potential of chitosan membranes ionically crosslinked with TPP and loaded with NQ14 against the B16F10 melanoma cell line was confirmed through in vitro cytotoxicity studies assessed via MTT assay. The anti-proliferative effect of prepared membranes was directly related to the amount of cross-linker and among all membranes prepared, such that one crosslinked with 0.3% of TPP may become a potential delivery system for releasing NQ14 drug for cancer therapy.

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials.

Inexpensive Apparatus for Fabricating Microspheres for 5-Fluorouracil Controlled Release Systems

The aim of this study was to develop an inexpensive apparatus for fabricating microspheres, based on chitosan, for 5-fluorouracil (5-FU) controlled release. Chitosan microspheres were prepared by precipitation method and the effects of manufacturing parameters (injection and airflow rates) on size distribution microspheres were analyzed by optical and scanning electron microscopy. The results show that the manufacturing parameters, injection and airflow rates, determine the microsphere size distribution. By modulating these parameters, it was possible to produce chitosan microspheres as small as 437 ± 44 μm and as large as 993 ± 18 μm. Chitosan microspheres loaded with 5-FU were also produced using the experimental equipment. The obtained microspheres presented 5-FU controlled release, indicating that the microspheres can be used orally, since they are capable of crossing the stomach barrier and of continuing with the process of 5-FU release.

Síntese e caracterização de arcabouços de quitosana com agente antineoplásicos

The controlled release system of drugs through the use of polymeric biomaterials compounds associated with antineoplastic action can be employed as an alternative treatment of neoplasms. Thus, this study had as objective the synthesis and characterization of the systems of scaffolds of chitosan loaded with the antineoplastic agent (1,4-naphthoquinone), whose release rate can be controlled by using a crosslinking agent such as sodium tripolyphosphate (TPP). The preparation method consisted of solubilizing the chitosan in acetic acid, drug addition, freezing, lyophilization and crosslinking TPP. All samples were characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), degree of swelling and enzymatic biodegradation. SEM showed the formation of interconnected pores with varying shapes and sizes in all the studied structures characterizing the formation of scaffolds. In EDS the presence of chemical elements characteristic of the chemical composition of each material was observed. However, the presence of sodium was observed which can be related to the neutralization agent used. The crosslinking of the scaffolds was confirmed by XRD and EDS which increased the enzymatic degradation rate in vitro in the same sample. The incorporation of the drug was confirmed by XRD, degree of swelling and EDS. Thus, it can be concluded that occurred the formation of crosslinked and non-crosslinked porous scaffolds with morphological and physicochemical properties that can contribute to the carrying of antineoplastic drugs, being possible to control the degradation rate thereof and probable the release of the drug.

Glass Ionomer Cement – Development and Characterization Microstructural

The Glass Ionomers Cements (GICs) are materials widely used in dentistry, have advantages such as fluoride release and chemical adhesion to the dental substrate. They are recommended as a restorative material, luting agent in prosthetic dentistry and also in medicine. However, there is need for developing new bone cements as an alternative or replacement to the current polymethylmethacrylate cements, therefore, the objective of this research was to develop an experimental GIC and characterization regarding morphology, chemical composition and crystallinity. This composite was characterized by X-ray diffraction (XRD), Infrared Spectroscopy Fourier Transform (FTIR) and optical microscopy (OM). For comparative study, was used the GIC Vidrion R (SS White) in the control group. These cements are presented in semi-crystalline diffraction patterns, the FTIR spectra observed characteristic bands of these materials and microstructural study of the cements showed homogeneous distribution of filler in the polymer matrix, corroborating with the literature.

Hydroxyapatite/Biopolymers Composite Scaffolds for Bone Tissue Engineering

The application of a hybrid composite consisting of biopolymer and calcium phosphate, similar morphology and properties of natural bone, may be a way to solve the problem of the fragility of ceramics without reducing its mechanical properties, retaining the properties of biocompatibility and high bioactivity. This work aims at the preparation and characterization of three-dimensional scaffolds composite HA / biopolymers (chitosan and gelatin). The freeze-drying technique was employed in this study to obtain these frameworks and partial results showed the effectiveness of this method. This involved the study of structural, chemical and morphological frameworks, in order to direct the research suggested the application. The X Ray Diffraction (XRD) and infrared spectroscopy and Fourier transform (FTIR) results confirmed the formation of hydroxyapatite (HA) phase and the presence of characteristic bands of HA and biopolymers in all compositions. The microstructure of the scaffolds study conducted by Scanning Electron Microscopy (SEM) revealed the formation of longitudinally oriented microchannels with interconnected pores. In all compositions the porous scaffolds showed varying sizes and mostly larger than 100μm, and is therefore considered materials with potential for application in bone tissue engineering.