Human schistosomiasis mansoni: studies on in vitro granuloma modulation

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to delayed hipersensitivity that results in granulomatous inflamatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflamatory disease is appsrently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor transactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We repport here on experiments wich extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the present of intact (F(ab')2 immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals. These data support the hypothesis that anti-SEA cross reactive idiotypes are important in regulating granulomatous hypersensitivy in chronic intestinal schistosomiasis patients and these cross-reactive idiotypes appear to play a major role in cell-cell interactions which result in the regulation of anti-SEA cellular immune responses.

Human B19 parvovirus infetion: an example of multiple pathogenic effects determined by differences in host susceptibility

B19 infection offers some general lessons about human viruses and their possible effects on the human host, as follows: (1) Ubiquitous apparently benign viruses may have severe effects on a compromissed host. The virus may be invariable but the host can have diverse susceptibilities. (2) B19 and some other human viruses (through for none is the evidence so clear as for B19) have narrowly targetted effects. The host cell of B19 is a specialised progenitor of mature red cells: impairment of the function of this cell by B19 may cause profound anaemia. (3) The 'normal'host response to B19 may also cause disease, though this is slef limiting. (4) The effects of malfunction of the virus'target cell are exacerbated when the immune response is impaired by congenital or acquired immunodeficiency, immunosupressive therapy or, in the case of the fetus, developmental immaturity that allows the virus to persist.

Pharmacokinetic profile of two different pharmaceutical forms of theophylline (a slow release tablet and a syrup) after multiple dose administration to healthy human volunteers

Due to the narrow therapeutic range of theophyline, plasma concentrations of this drug are monitored in patients undergoing chronic therapy. Slow-release preparations avoid the fluctuations in plasma levels and improve patient compliance. In this study, we have compared the pharmacokinetic profiles of a theophylline slow-release tablet and a syrup form, when administered in multiple doses to healthy adult volunteers. The classification based upon releasing patterns is confirmed.

Immunogenicity of multiple antigen peptides containing Plasmodium vivax CS epitopes in BALB/c mice

Multiple antigen peptide systems (MAPs) allow the incorporation of various epitopes in to a single synthetic peptide immunogen. We have characterized the immune response of BALB/c mice to a series of MAPs assembled with different B and T cell epitopes derived from the Plasmodium vivax circumsporozoite (CS) protein. A B-cell epitope from the central repeat domain and two T-cell epitopes from the amino and carboxyl flanking regions were used to assembled eight different MAPs. An additional universal T cell epitope (ptt-30) from tetanus toxin protein was included. Immunogenicity in terms of antibody responses and in vitro T lymphocyte proliferation was evaluated. MAPs containing B and T cell epitopes induced high titers of anti-peptides antibodies, which recognized the native protein on sporozoites as determined by IFAT. The antibody specificity was also determined by a competitive inhibition assay with different MAPs. A MAP containing the B cell epitope (p11) and the universal epitope ptt-30 together with another composed of p11 and the promiscuous T cell epitope (p25) proved to be the most immunogenic. The strong antibody response and specificity for the cognate protein indicates that further studies designed to assess the potential of these proteins as human malaria vaccine candidates are warranted.

Multiple isolates from Aids patients: aspects of an analysis by a genotypic marker and antimicrobial susceptibilities variations

Twenty-one Mycobacterium avium multisolates, from ten human immunodeficiency virus-infected patients, were typed by restriction fragment length polymorphism using as marker the IS1245 and characterized by minimum inhibitory concentration for nine different antibiotics. Two out of four patients harboring multisolates with different fingerprint profile, were therefore considered as having a polyclonal infection, since their isolates were taken from sterile site. This result confirms that polyclonal infection caused by M. avium occurs with a nonnegligenciable frequency. Analyzing the multisolates susceptibility profile of each patient it was observed that most of them were infected with strains having appreciably different antimicrobial susceptibility patterns, no matter what the genotypic pattern of the strains was. These results have strong implication for the treatment of the patients.

Education for science and science for education: more than a play upon words

In the celebration of the Oswaldo Cruz Institute centenary, we wanted to stress our concern with the relationship between two of its missions: research and education. What are the educational bases required for science and technology activities on health sciences for the future years? How can scientists collaborate to promote the popularization of academic knowledge and to improve a basic education for citizenship in an ethic and humanistic view? In this article we pointed out to need of commitment, even in the biomedical post-graduation level, of a more integrated philosophy that would be centered on health education, assuming health as a dynamic biological and social equilibrium and emphasizing the need of scientific popularization of science in a cooperative construction way, instead of direct transfer of knowledge, preserving also macro views of health problems in the development of very specific studies. The contemporary explosion of knowledge, particularly biological knowledge, imposes a need of continuous education to face the growing illiteracy. In order to face this challenge, we think that the Oswaldo Cruz Institute honors his dialectic profile of tradition and transformation, always creating new perspectives to disseminate scientific culture in innovated forms.

Hepatitis C prevalence and risk factors in hemodialysis patients in Central Brazil: a survey by polymerase chain reaction and serological methods

An hemodialysis population in Central Brazil was screened by polymerase chain reaction (PCR) and serological methods to assess the prevalence of hepatitis C virus (HCV) infection and to investigate associated risk factors. All hemodialysis patients (n=428) were interviewed in eight dialysis units in Goiânia city. Blood samples were collected and serum samples screened for anti-HCV antibodies by an enzyme-linked immunosorbent assay (ELISA). Positive samples were retested for confirmation with a line immunoassay (LIA). All samples were also tested for HCV RNA by the PCR. An overall prevalence of 46.7% (CI 95%: 42-51.5) was found, ranging from 20.7% (CI 95%: 8.8-38.1) to 90.4% (CI 95%: 79.9-96.4) depending on the dialysis unit. Of the 428 patients, 185 were found to be seropositive by ELISA, and 167 were confirmed positive by LIA, resulting in an anti-HCV prevalence of 39%. A total of 131 patients were HCV RNA-positive. HCV viremia was present in 63.5% of the anti-HCV-positive patients and in 10.3% of the anti-HCV-negative patients. Univariate analysis of risk factors showed that the number of previous blood transfusions, transfusion of blood before mandatory screening for anti-HCV, length of time on hemodialysis, and treatment in multiple units were associated with HCV positivity. However, multivariate analysis revealed that blood transfusion before screening for anti-HCV and length of time on hemodialysis were significantly associated with HCV infection in this population. These data suggest that nosocomial transmission may play a role in the spread of HCV in the dialysis units studied. In addition to anti-HCV screening, HCV RNA detection is necessary for the diagnosis of HCV infection in hemodialysis patients.

Morphological investigation of Toxoplasma gondii in vivo by a multiple beam interference microscope

A recently developed technique, namely multiple beam interference microscopy, has been applied to investigate the morphology of the parasite Toxoplasma gondii for the first time. The interference pattern obtained from the multiple internal reflection of a T. gondii, sandwiched between a glass plate and a cover plate, was focused on the objective of a conventional microscope. Because of the enhance contrast, several details of sub cellular structure and separating compartments are clearly visible. Details reveal the presence of a nucleus, lipid body, dense granule, rhoptry and amylopectin. The wall thickness of the membrane of the lipid body and the amylopectin is of the order of 0.02 µm and can be clearly distinguished with the help of the present technique. The same parasite has also been examined with the help of atomic force microscopy, and because of its thick membrane, the inner structural details were not observed at all. Sub cellular details of T. gondii observed with the present technique have been reported earlier only by low amplification transmission electron microscopy and not by any optical microscopic technique.

Schistosomiasis protects against multiple sclerosis

The incidences of schistosomiasis and multiple sclerosis (MS) are mutually exclusive worldwide suggesting that schistosomiasis may offer protection against the induction of the immune-mediated disease, MS. Recent studies using the mouse model of MS, experimental autoimmune encephalomyelitis, support a direct suppression of the onset of MS by chronic Schistosoma mansoni infection. Self-reactive Th1 but not Th2 responses develop in infected mice immunized with myelin oligodendrocyte glycoprotein albeit at reduced levels indicating that the induction of auto-reactive T cells is not abolished nor phenotypically altered. CNS infiltration by inflammatory cells, particularly macrophages, is significantly reduced in S. mansoni-infected, immunized mice compared to uninfected, immunized mice. Because activated macrophages are crucial to the induction of clinical disease, these findings support the hypothesis that differences in macrophage activation may contribute to the reduced incidence and delayed progression of experimental autoimmune encephalomyelitis during schistosomiasis.

Taeniasis-cysticercosis in Southern Ecuador: assessment of infection status using multiple laboratory diagnostic tools

Taenia solium-taeniasis and cysticercosis were studied in the human and porcine populations of a rural community in the Southern Ecuadorian Andes. From the 1059 inhabitants, 800 serum samples and 958 stool samples could be collected. In addition, 646 from the estimated 1148 pigs were tongue inspected. Circulating antigen was detected by enzyme linked immunosorbent assay (Ag-ELISA) in 2.25% of the human population, whereas intestinal taeniasis was detected in 1.46% by the formalin-ether technique. Following treatment and recovery of tapeworm fragments these were all identified as T. solium. Porcine cysticercosis was diagnosed in 3.56% of the pigs by tongue inspection. In addition, enzyme linked immunoelectrotransfer blot (EITB) was performed on a subset group of 100 humans to confirm the results of the Ag-ELISA. One hundred serum samples from pigs were also analysed by EITB. It appeared that 43 and 74% of humans and pigs had antibodies against T. solium cysticerci, respectively. It is concluded that contrary to the high exposure of the human population to T. solium that is suggested by EITB, the number of active cysticercosis cases, diagnosed by Ag-ELISA, was low, which may indicate endemic stability. The further use of complementary diagnostic methods for a better understanding of the epidemiology of T. solium is suggested.

Analysis and estimative of schistosomiasis prevalence for the state of Minas Gerais, Brazil, using multiple regression with social and environmental spatial data

The aim of this work is to establish a relationship between schistosomiasis prevalence and social-environmental variables, in the state of Minas Gerais, Brazil, through multiple linear regression. The final regression model was established, after a variables selection phase, with a set of spatial variables which contains the summer minimum temperature, human development index, and vegetation type variables. Based on this model, a schistosomiasis risk map was built for Minas Gerais.

Genetic variability of Aedes aegypti in the Americas using a mitochondrial gene: evidence of multiple introductions

To analyze the genetic relatedness and phylogeographic structure of Aedes aegypti, we collected samples from 36 localities throughout the Americas (Brazil, Peru, Venezuela, Guatemala, US), three from Africa (Guinea, Senegal, Uganda), and three from Asia (Singapore, Cambodia, Tahiti). Amplification and sequencing of a fragment of the mitochondrial NADH dehydrogenase subunit 4 gene identified 20 distinct haplotypes, of which 14 are exclusive to the Americas, four to African/Asian countries, one is common to the Americas and Africa, and one to the Americas and Asia. Nested clade analysis (NCA), pairwise distribution, statistical parsimony, and maximum parsimony analyses were used to infer evolutionary and historic processes, and to estimate phylogenetic relationships among haplotypes. Two clusters were found in all the analyses. Haplotypes clustered in the two clades were separated by eight mutational steps. Phylogeographic structure detected by the NCA was consistent with distant colonization within one clade and fragmentation followed by range expansion via long distance dispersal in the other. Three percent of nucleotide divergence between these two clades is suggestive of a gene pool division that may support the hypothesis of occurrence of two subspecies of Ae. aegypti in the Americas.

Molecular characterization of astrovirus in stool samples from children in São Paulo, Brazil

The purpose of this study was to characterize astrovirus in faecal samples collected from children with and without diarrhea in São Paulo, Brazil, grouped into two sets: EPM and HU. Detection and genotyping were carried out using reverse transcription nested polymerase chain reaction (RT-PCR) with specific primers directed towards the genome open reading frame 2 (ORF2). Results for EPM set showed that 66/234 (28.2%) were positive: 28/94 (29.7%) from children with acute diarrhea, 14/45 (31.1%) with persistent diarrhea, and 9/55 (16.3%) from control individuals. No data was available for 15/40 (37.5%) of samples. Mixed infections with other viruses were found in 33 samples. In the HU, 18/187 (9.6%) were positive: 12/158 (7.6%) from individuals with acute diarrhea and 6/29 (20.7%) from control children. Four samples were mixed with other viruses. Out of 66 astrovirus positive EPM samples, 18 (27.2%) were characterized as human astrovirus type-1 (HAstV-1), two (3.0%) as HAstV-2, two (3.0%) as HAstV-3, and three (4.5%) as HAstV-8. Among 18 astrovirus positive HU samples, one (5.5%) was characterized as HAstV-1, six (33.3%) as HAstV-2, and one (5.5%) as HAstV-8. Two HAstV-8 genotyped samples were further confirmed by nucleotide sequencing. Our results shows that astroviruses are circulating in a constant manner in the population, with multiple serotypes, in higher frequency than it was described for other Brazilian regions. For the first time in Sao Paulo, Brazil, it was shown that astroviruses play an important role in children gastroenteritis, as described for most locations where they were detected.