MC3T3-E1 cell response to microporous tantalum oxide surfaces enriched with Ca, P and Mg.

The formation of a porous oxide surface doped with osteoconductive elements, Ca, P and Mg, to enhance osseointegration, was achieved through micro arc oxidation. Micro arc oxidation parameters, such as electrolyte composition, concentration and applied voltage, were studied to understand their effect on the morphology and chemical composition of the samples surface. Considering the optimum atomic concentration reported in literature for each osteoconductive element, microporous Ta anodic oxide samples treated with calcium acetate (CaA) and ß-glycerophosphate (ß-GP) revealed that an increase of ß-GP molarity in the electrolyte boosts Ca incorporation, as well as, increasing the porosity. In adding magnesium acetate (MgA) to the electrolyte, when composed by CaA + ß-GP, both addition and variation of MgA did not affect the surface morphology along the samples, being incorporated into the oxide layer for 0.1 M. Finally, in vitro tests were carried out to study the biocompatibility of Ta, to verify the cytotoxicity of the samples and their behavior towards cells, by performing adhesion and differentiation tests with the MC3T3-E1 cell line. Cytotoxicity tests revealed that the samples were non-toxic. Despite none of the samples having been raised up through cell adhesion tests, cell differentiation revealed promising results for the Ta-CaP.

241Am-Be(α,n) CHARACTERIZATION FOR A NEW LABORATORY FACILITY IN BRAZIL.

The Laboratório de Ciências Radiológicas is developing an irradiator for neutron survey meters calibration. Part of this work is related to the characterization of the neutron source that will be used in the irradiator. Therefore, a source of 241Am-Be(α,n) was characterized according to the following attributes: neutron energy distribution, anisotropy and emission rate. In order to make these values into high-level metrological references traceable by the Bureau International des Poids et Mesures, these measurements were taken at the Neutron Laboratory part of the Laboratório Nacional de Metrologia das Radiações Ionizantes. Results obtained for the source spectrum have strong adherence to the reference spectrum established by ISO 8529-1. The new laboratory for neutron calibration will allow calibration in an approximate ambient dose equivalent ranging 20-4500 µSv/h.

Bioactivity response of Ta1-xOx coatings deposited by reactive DC magnetron sputtering.

The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft-hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar+O2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates.

Influence of albumin on the tribological behavior of Ag-Ti (C, N) thin films for orthopedic implants.

With the increase of elderly population and the health problems arising nowadays, such as cancer, knee and hip joint prostheses are widely used worldwide. It is estimated that 20% of hip replacement surgeries simply fail after 5years, due to wear loosening, instability and infection. In this paper it is reported the study of advanced materials with the ability to overcome some of these drawbacks. The development of ceramic coatings, based on carbonitrides of transition metals, such as TiCN, doped with silver, Ag, may represent an effective solution. Thin films of Ag-TiCN were produced by dc reactive magnetron sputtering with silver contents ranging from 4 to 8at.%. The physical, chemical, structural, morphological/topographical, mechanical and tribological properties were evaluated. The tribological tests were performed in a unidirectional wear simulator, pin on disk, being the antagonists of a ceramic Al2O3 ball, and using simulate body fluids as lubricant. Hank's Balanced Salt Solution (HBSS) and bovine serum albumin (BSA) in HBSS were chosen, in order to evaluate the lubrication ability of the solution containing the protein, albumin. The results revealed that the coatings with Ag content ranging from 4 to 8at.%, were the most promising, as the tribological properties were superior to the results reported by other authors, which also developed Ag-TiCN coatings containing similar Ag contents and using similar test conditions. The presence of albumin leads to a lower wear in all the test conditions, and this enhancement was higher in the hydrophobic surfaces.

Humoral immunological profile and parasitological statuses of Leishmune vaccinated and visceral leishmaniasis infected dogs from an endemic area.

Dogs represent the major reservoir of Leishmaniao chagasi and vaccination against the canine disease is a potential control strategy. However, seroconversion occurs post-vaccine and hence, there is need to discriminate between the former group and naturally infected dogs. The present study represents a comparison of the humoral immunological profiles of both groups using Leishmania soluble antigen (LSA) and fucose-mannose ligand (FML). For both categories, ear skin samples were evaluated immunohistochemically and through PCR, that was also performed in blood specimens, as well as their ability to infect Lutzomyia (Lutzomyia) longipalpis. All these tests showed negative results for the vaccinated dogs. Differences between groups were observed regarding IgG, IgG2 and IgE absorbances as determined by FML-ELISA, and for IgG1 and IgE absorbances as measured by LSA-ELISA, showing that Leishmune-immunised animals and VL naturally infected dogs present different immunological profiles, even though these differences cannot be used to distinguish between these two groups of dogs.

Efficacy of atovaquone and sulfadiazine in the treatment of mice infected with Toxoplasma gondii strains isolated in Brazil.

The efficacy of atovaquone and sulfadiazine was examined alone or in combination for the treatment of mice infected with six Brazilian Toxoplasma gondii strains previously genotyped using the PCR-RFLP assays of the SAG2 gene, in addition to RH strain. Swiss mice were infected intraperitoneally with 10(2) tachyzoites from each strain of T. gondii and treated with 6.25, 12.5, 25 and 50 mg/Kg/day of atovaquone or 40, 80, 160 and 320 mg/Kg/day of sulfadiazine. In a second experiment, mice were treated with the association of previously determined doses of each drug. Treatment started 48 hours post-infection, and lasted 10 days. The susceptibility of T. gondii to atovaquone and to sulfadiazine was different according to the parasite strain. It was observed strains that are susceptible to atovaquone, and strains that are resistant to it. Type I strains were more susceptible to the activity of sulfadiazine and more resistant to atovaquone. Yet type III strains were susceptible to atovaquone and to sulfadiazine. Association of atovaquone and sulfadiazine presented a synergic effect in the treatment of mice infected with RH type I strain and an additive effect in the treatment of mice infected with one type I strain and with two type III strains.

Influence of the long-term Trypanosoma cruzi infection in vertebrate host on the genetic and biological diversity of the parasite.

The influence of the long-term Trypanosoma cruzi infection in vertebrate host on the biological and genetic properties of the parasite was evaluated. Four T. cruzi isolates obtained from different chronic chagasic dogs infected with Berenice-78 T. cruzi strain during 2 and 7 years were comparatively analyzed. The long-term T. cruzi infection has led to alterations in parasitemia, virulence and pathogenicity of Be-78 strain for mice. These biological parameters varied from low to high in realation to the parental strain. Randomly amplified polymorphic DNA and isoenzyme profiles detected two distinct genetic groups of parasites. The first group included the parental strain and two T. cruzi isolates, and the second group the two other isolates. Interestingly, the isolates of the second group showed a reversibility of the genetic profile to the parental strain after 25 passages in mice. No correlation between the genetic groups and biological properties of the isolates was observed. Our findings confirmed the population heterogeneity of the Be-78 strain, and showed how differently it responds to the long-term infection in the same vertebrate hosts.

Identifying cyclosporine blood levels associated with the prevention of renal transplant rejection: a single-center, randomized prospective study.

Multiple-drug therapy may allow reduced individual drug doses with fewer side effects. Blood levels of cyclosporine (CsA) necessary to avoid rejection may vary with different drug combinations. Fifty-eight kidney transplant patients were randomized into two groups: 25 subjects were assigned to the 4-hour area under the curve (AUC(0-4)) Cohort-the "high arm" (4500 to 5500 ng . h/mL)--1 and 33 to the AUC(0-4) "low arm" (2400 to 3400 ng . h/mL). After CsA introduction, AUC(0-4) was drawn on days 4, 7, 14, 21, 28, 42, 56, 70, 84, 90. We compared the proportion of rejection versus rejection-free patients, according to the CsA exposure. Logistic regression analysis showed that an AUC(0-4) of > or =4000 ng . h/mL or a 2-hour cyclosporine level (C(2)) of > or =1450 ng/mL predicted a rejection-free course among patients not receiving induction therapy. When either basiliximab or thymoglobulin was administered, a C(2) and AUC(0-4) of 1043 +/- 151 ng/mL or 3146 +/- 262 ng . h/mL, respectively, were associated with a rejection-free course. Our findings confirm the need for different CsA levels to prevent rejection according to induction therapy. Induction with either basiliximab or thymoglobulin allows reduced CsA levels during the first 3 months after renal transplantation.

Effects of specific treatment on parasitological and histopathological parameters in mice infected with different Trypanosoma cruzi clonal genotypes.

The goal of this study was to verify the effect of specific treatment on parasitological and histopathological parameters in mice experimentally infected with different Trypanosoma cruzi clonal genotypes. Twenty cloned stocks were selected, representative of the whole phylogenetic diversity of the protozoan and belonging to the clonal genotypes 19 and 20 (T. cruzi I) and 39 and 32 (T. cruzi II). The stocks were inoculated in 40 BALB/c mice divided into four groups: (i) treated with benznidazole, (ii) treated with itraconazole and (iii and iv) untreated control groups (NT) for each drug, respectively. Seven parameters related to parasitaemia curves and histopathological lesions were analysed. Four during the acute phase (AP) and three during both the AP and chronic phase (CP) of infection. Statistical comparison between benznidazole-treated and NT groups for the biological parameters showed significant differences for all genotypes. Benznidazole treatment led to lower patent period, maximum of parasitaemia, day of maximum parasitaemia and area under the parasitaemia curve for all genotypes analysed. Percentage of positive haemoculture during AP and CP was lower for genotypes 19 and 32. Tissue parasitism (TP) and inflammatory process (IP) during AP were lower for genotypes 19 and 32, respectively. In general, itraconazole treatment induced a smaller reduction in these same parameters between treated and NT animals in relation to benznidazole treatment. Our results indicate that phylogenetic divergence among T. cruzi clonal genotypes must be taken in account in chemotherapy and studies dealing with all aspects of the parasite and the disease.

Localization of the gene for sclerosteosis to the van Buchem disease-gene region on chromosome 17q12-q21.

Sclerosteosis is an uncommon, autosomal recessive, progressive, sclerosing, bone dysplasia characterized by generalized osteosclerosis and hyperostosis of the skeleton, affecting mainly the skull and mandible. In most patients this causes facial paralysis and hearing loss. Other features are gigantism and hand abnormalities. In the present study, linkage analysis in two consanguineous families with sclerosteosis resulted in the assignment of the sclerosteosis gene to chromosome 17q12-q21. This region was analyzed because of the recent assignment to this chromosomal region of the gene causing van Buchem disease, a rare autosomal recessive condition with a hyperostosis similar to sclerosteosis. Because of the clinical similarities between sclerosteosis and van Buchem disease, it has previously been suggested that both conditions might be caused by mutations in the same gene. Our study now provides genetic evidence for this hypothesis.

[Profile of HIV-positive women hospitalized in a public maternity ward in Rio de Janeiro]. / Perfil de mulheres portadoras do HIV de uma maternidade no Rio de Janeiro.

AIDS has been scaring the world population for the last decades. The writers of this article decided to investigate and research into the high incidente of women HIV+ hospitalized in a public maternity in the district of Rio de Janeiro, showing the profile of pregnant women from 1987 to 1996. After a thorough analysis of a total of 102 cases this number was eventually broken down showing that the majority of the female population are single, between the ages of 19 and 33 years, have low schooling, mainly housewives and were sexually contaminated. The results show that the affected groups lack the knowledge as to how they could protect themselves against contamination. It is, therefore, of vital importance to take the necessary measures to help prevent contamination and to focus on health education.

Spinal cord injury: patients who had an accident, walked but became spinal paralysed.

Out of 1410 patients admitted to the spinal cord injury unit (SARAH) for rehabilitation during a 10-year period (1981-90) 10 had a missed spinal trauma lesion and became paralysed after having overcome the initial injuries and being allowed to walk. Patients were admitted to hospital with a history of being able to walk after an accident and subsequently developing a neurological deficit. Seven patients had radiological findings compatible with instability of the spine. Four had a head injury with coma and an undetected spinal fracture at the first evaluation in the emergency room. Other associated factors were: spinal stenosis, prolapsed disc, infection, foreign bodies, procedures for reduction and stabilization of the fractured spine. We emphasize the need for very careful clinical study and investigation for the diagnosis of multiinjured patients, especially when there is a concurrent brain injury.