Navegando por Orientadores "SILVEIRA, Fernando Tobias"

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Acesso aberto (Open Access)
Avaliação da susceptibilidade do primata Cebus apella (Primates: Cebidae) à infecção experimental com diferentes inóculos de Leishmania (Leishmania) chagasi
(Universidade Federal do Pará, 2005) SANTOS, Dirceu Costa dos; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
In Brazil, the monkey Cebus apella has been successfully used as a model for studying cutaneous leishmaniasis. Thus, we decided to investigate its usefulness as a model for visceral leishmaniasis. For this purpose, we used 10 specimens of C. apella: 7 males and 3 females, juveniles. All were born and raised in captivity. In the first experiment was realize with 6 monkeys divided in 2 groups, in the first group with 3 monkeys was inoculated with 30 x 106 promastigotes of L. (L.) chagasi (MCAO/BR/1998/M18011, Maranhão State) from stationary phase of cultures, while in the second group with 3 monkeys was inoculated 5 doses successive with 30 x 106 promastigotes (150 x 106) of L. (L.) chagasi (MCAO/BR/1998/M18011, Maranhão State) from stationary phase of cultures. In the second experiment were used 4 monkeys, divided in 2 groups was also inoculated with five pairs of salivary glands of Lutzomyia longipalps together with parasites. In the first group with 2 monkeys was inoculated with 30 x 106 promastigotes of L. (L.) chagasi, second group with 2 monkeys was inoculated 5 doses successive with 30 x 106 promastigotes (150 x 106). The inoculations were, intradermaly, into the base of the tail of the animals. The evaluation of infections was monthly and included clinical examination, IgG antibody response (IFAT). In monkeys inoculated with promastigotes only or in those inoculated with promastigotes plus the salivary glands of the flebotominae sand fly we have till now found no clinical manifestations of infection all the experiment, neither have demonstrated parasites in the bone-marrow or specific antibody response. These results suggest that C. apella monkey is able to resist against to infection by L. (L.) chagasi.
Acesso aberto (Open Access)
Caracterização isoenzimática e por anticorpos monoclonais dos agentes da leismaniose tegumentar americana (LTA) na mesorregião do Baixo Amazonas, estado do Pará, Brasil
(Universidade Federal do Pará, 2003) JENNINGS, Yara Lúcia Lins; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
There are a diversity of Leishmania species in the Amazon region responsible for cutaneous leismnaniasis and although a high occurence of the disease is known in the lower Amazon region, little information exists regarding the etiological agents. For this reason the present study has set out to characterise strains of Leishmania isolated from patients coming from this area by enzyme electroforesis, to confirm the presence of Leishmania species already recorded in other parts of Amazonia and to detect possible intraspecific variation. For identification of 43 isolate obtained, 7 reference-strains of Leishmania species from other regions of Pará were selected for comparison by way of isoenzyme eletrophoresis, using the seven enzymes 6PGDH, PGM, G6PD, MPI, ASAT e ALAT. The isolates had previously been examined by the indirect immunofluorescence teste (IFAT), using the biotin-avidin system and battery of 23 monoclonal antibodies (McAbs). Identifications by the isoenzyme eletrophoresis were as follows: 20(46,50%) strains of L. (V) guyanensis, 11 (25,28%) of L. (V) braziliensis, 6 (13,950/0) of L. (V) lainsoni, 4 (9,300/0) of L. (V) shawi and 2 (4,60%) de L. (L.) amazonensis. Enzyme eletrophoresis, using the above mentioned enzymes proved of high value in identification. For the first time in the lower amazon region, it was possible to detect the occurence of intraspecific variation indicating the presence of 3 different serodemes among the strains of L. (V) braziliensis. Arnong the strains of L. (V) guyanensis there were observed two variants: one which showing reation against McAb B19, considered to be specific for this parasite, but with variation for the enzymes 6PGDH and PGM, and another with no reaction against McAb B19 but showed enzymatic profiles similar to the reference strain of that parasite, especially 6PGDH (but with 3 bands) and PGM, which are considered to be the best enzyme markers. The presence of all 5 dermotropic Leishmania spp. Already know to variably exist in other parts of north Brazil suggests sympatric transmission within the lower Amazon region of the present study.
Acesso aberto (Open Access)
Estudo in vitro da infectividade de espécies de Leishmania do subgênero Viannia em macrófagos peritoneais de camundongo BALB/c
(Universidade Federal do Pará, 2003) CAMPOS, Marliane Batista; GOMES, Claudia Maria de Castro; http://lattes.cnpq.br/8660496919187291; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
Parasites ofthe genus Leishmania show both intra- and inter-specific variations of infectivity. There is little available information, however, regarding the infective behavior of New World species particularly those of the Amazon Region of Brazil, where there occur at six species of the subgenus Viannia causing human cutaneous leishmaniasis (ACL). The aim of the present study was to investigate the infectivity of 5 of these species for the peritoneal macrophages of BALB/c mice, and their role in the host-cell's production of nitric oxide (NO). Thirty strains of Leishmania were divided into 6 groups of the fol1owing species: I-L. (V.) braziliensis (from cases of localized skin lesions-LCL); II- L. (V.) braziliensis (from cases of mucocutaneous lesions- LeM); III- L. (V.) guyanensis; IV- L. (V.) shawi; V- L. (V.) naiffi and VI- L. (V.) lainsoni. They were cultivated in RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% penicillin/gentamicin, until reaching the stationary phase of development. These promastigotes were used to infect the macrophage cell cultures, in the proportion of 4 flagellates/macrophage. The cultures were then incubated at 35°C with 5% CO2 and, after 24 hours following inoculation, the corvelips were stained by Giemsa's method to determine the infection index. The nitric oxide (nitrite) concentration was measured in the culture supernatant by Griess' s method to determine the infection index. The nitric oxide (nitrite) concentration was measured in the culture supernatant by Griess' s method. It was found that LCM strains of L. (V.) braziliensis showed the highest infection index (385), significance p<0.05,compared with L. (V.) braziliensis LCL strains (264). L. (V). naiffi and L. (V.) lansoni had the lowest infection indices of (215) and (272), respectively, but, were not significally different from index of L. (V.) guyanensis (300). Rrgarding the NO levels, the highest was that for L. (V.) naiffi (4,1µM), and the lowest for L. (V.) braziliensis-LCM strains (2, 15µM). The other readings were (3,14µM) for L. (V.) lainsoni, 2,96µM for L. (V.) shawi, 2,76µM for L. (V.) guyanensis and 3,1µM for L. (V.) braziliensis-LCL strains. It is conc1uded that L. (V.) natffi. In this way it may be noted the NO levels for infected macrophage were inversely proportional to the degree of infectivity of the species studied.
Acesso aberto (Open Access)
Forma oligossintomática da leishmaniose visceral americana: aspectos clínico e soroepidemiológico
(Universidade Federal do Pará, 2003) ATHAYDE, Aidalucy do Socorro Costa de; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
The american visceral leishmaniasis (LVA) is a infectious disease, no contagious of chronic evolution and high mortality rate, being Brazil holder of 90% of the cases notified in the American continent. However, they still are not explained in an objective way the signs and symptoms of the subclinical infection, causing retard or confusion in the diagnosis of the disease. In this sense, the present work intended to previously accompany clinic and serologically the defined population, in order to characterize the subclinical form of LVA, and to study the prevalence and incidence of the infection. 307 individuals were accompanied, infected or not for the Leishmania chagasi , children and adults from 61 households, residents of the place Cabresto, Barcarena-Para, selected through clinical exam and the specific antibodies was detected by immunofluorescence reaction, between january 2000 and january 2001. For the calculation of the incidence of the infection and clinical determinant were excluded of the sample 06 patients that had already developed the classic form of the disease, in previous period. The statistical analysis was accomplished with aid of aid of the program EPINFO 0.04 and BioEstat 2.0, and the applied tests were the Quisquare, Exact Test of Fisher and G Test. In the moment of the first exam (serologically selection), 34 (11%) patients had positive serologically for the infection, however 06 of those patient ones, they had already developed the classic manifestations of LVA, elapsed the 12 months of the research appeared more 09 individuals with positive serologically of larger titles or same to ]/320, making an full of 43 (14%) infected patients by the parasite. Among the infected patients: the age groups of larger concentration were the one of young individuals, up to 24 years of age (44%); the sex of larger predominance was the male with 28 (65,1%); the signs and obvious symptoms or noticed by the subclinical individuals (5,5%), they were: paleness cutaneous-mucous membrane, lymphadenopathy, heart alteration, hepatomegaly, abdominal larging and cough. The tax of incidence of the infection was of 2,9%. None of the infected patients presented exacerbation of the symptoms or similarity manifested with the sharp form of the disease, during the twelve months of study, same when they presented higher titles of the serologically compatible with to those of patients in the classic way of LVA.
Acesso aberto (Open Access)
Infecção humana por Leishmania (Leishmania) chagasi em área endêmica de leishmaniose visceral no estado do Pará, Brasil: uma abordagem epidemiológica, clínica e imunológica
(Universidade Federal do Pará, 2010) ROSAS FILHO, Mário de Souza; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
A transeccional study was carried out in a cohort of 946 individuals of both sexes, from one year old and upwards, living in endemic area of American visceral leishmaniasis (AVL), municipality of Barcarena, northeast Pará, Brazil. The major aim of this study was to identify individuals with the symptomatic and/or asymptomatic infection due to Leishmania (L.) chagasi, and to study the two types of infection, both clinically and immunologicall. For diagnosis of infection there were used the indirect fluorescent antibody test (IFAT) and the leishmanin skin test (LST) with amastigotes and promastigotes antigens of Leishmania (Leishmania) chagasi, respectively. Results were scored as + to ++++: for the IFAT, serological titres (IgG) of 80-160 and 320-640 were given + and ++, with those of 1.280-2.560 and 5.120- 10.240 as +++ and ++++ respectively. For the LST, exacerbated reactions (³16mm) were regarded as ++++, strongly positive (13-15mm) as +++, moderately positive (9- 12mm) as ++, and weakly positive (5-8mm) as +. Analysis of the difference among the clinical-immunological profiles of infection was based on the programme BioEstat 4.0 and the X2 and Binomial tests with confidence of 95%. During the study, 12 infected persons showed high serological titres (1.280 to 10.240 IgG) with negative LST reactions: 5 children and 2 adults developed of AVL with IFAT titres ³ 2.560 (IgG) and a negative LST, and 2 children and 3 adults developed subclinical infections with IFAT titre of 1.280 (IgG) and a negative LST. In addition, the two tests enabled the identification of 5 different clinical-immunological profiles within the total of 231 cases of infection diagnosed, as follows: 1. 77% with asymptomatic infection (AI), with LST ranging from +/++++ and a negative IFAT; 2. 2% with symptomatic infection (SI = AVL) and 3. 1.3% with subclinical oligosymptomatic infection (SOI), both groups with a negative LST and IFAT ranging from +++/++++; 4. 9.9% with a subclinical resistant infection (SRI), showing both LST and IFAT with +/++, and 5. 9.8% with an indeterminate initial infection (III), with a negative LST and IFAT +/++. Regarding evolution of infection, the major observation was that only a single case of SI (= AVL) evolved from the profile III (23 cases), from which most infections evolved to the profiles SRI (9 cases) or SOI (5 cases) while the lastly 8 cases remained as III.
Acesso aberto (Open Access)
Leishmaniose visceral no município de Barcarena, Pará: importância do comportamento da enzootia canina por Leishmania (Leishmania) chagasi e de outros fatores para a infecção humana
(Universidade Federal do Pará, 2005) PEREIRA, Elza Alves; SILVEIRA, Fernando Tobias; http://lattes.cnpq.br/8106158306299969
The leishmaniasis is an infectious disease no contagious of chronic evolution with high mortality rate, and Brazil notifies about 90% of the cases of the American continent. His importance in the context of the public health has been increasing in function of the crescent number of cases that is happening not only in the rural area as well as in the periphery of great urban centers. The epidemiology of LV in Brazil is based on the occurrence of clinical cases. In this sense the present study intended to study the behavior of the canine infection and of other factors for the human infection. Because little it is known on the determinant of the infection and his importance in the maintenance of the disease. For that a place municipal district of Barcarena was defined, where the population is stable, happening the disease in an endemic way. The study accompanied during one year two cohorts, being one for canine teeth, with 172 dogs, and one for humans, with 1064 people of which only 1012 participated in the material collection, because 52 people were out of the strip of compatible age for the accomplishment of the procedures. The accomplishment of the test serology through the Reaction of Indirect Imunofluorescência (RIFI), she had as purpose the determination of the initial prevalence of infection and the incidences in two moments of the study, so much of the population human as canine. It was also accomplished in the human population Montenegro's Intradermo Reação (IDRM) with the same purpose, to check the prevalence and infection incidence through this method. Other factors were also analyzed and they can be associated to the risk for the infection. The statistical analysis of the data was accomplished with of the programs EPI INFO version 6.04 and BIOESTAT version 3.0 and the applied tests were Qui - Square and the prevalence calculation and incidence. In the inquiry canine serology it was observed a prevalence of canine infection of 37,2% and the incidence six months after, it was of 29,2%. In the interval of second for the third collection the euthanasia of the dogs positive serology was accomplished, in a total of 70 dogs, because 15 had died before the intervention. The incidence made calculations after the intervention showed a tax of 14,6%, what characterizes a reduction of about 50%. As for the titulation, in all of the stages titles were observed considered high. It is worth to stand out that of the 54 animals that didn't present clinical signs, 30 were infected (55,5%). When accomplished the inquiry human serology it was observed a prevalence of human infection of 5,25%, and the incidence six months after it was of 1,69% and in the it finishes evaluation 6,52%, with increase about 300% for RIFI, while for IDRM the initial prevalence was respectively of 10,78% and the incidences of 4,75% and 7,30% to the six and twelve months of the study. In relation to the characteristics of the population it was observed that she enters them infected there was not prevalence of any age group. The variable sex was not significant for the infection occurrence. On them infected so much by RIFI, as IDRM, stands out the statistical significance of the variable occupation, and in this context, the category farmer was the one that came with larger proportion. The variables time residence in the place, residence proximity with the forest, destiny of the garbage and dejections also showed - if significant. Although in the variable age group, the distribution of the infected by RIFI was not predominant in any strip; in IDRM, it was observed that as it increases the age also increases the proportion of having infected. Other results were observed of great relevance for the association to the infection risk, but the observation as to have infected for RIFI and IDRM it was the one that deserved prominence in function of the statistical significance. The study was shown appropriate goes the knowledge of the prevalences and incidences of canine and human infection in the place, the well the behavior of adds factors that associated they can be constituted in risk goes infection and that the elimination of dogs seropositives reduces the incidence of canine infection mean while no doesn't alter the course of the human infection, could have other wild reservoirs involved in the transmission.