Elizabeth Malagueño

New imidazolidinic bioisosters: potential candidates for antischistosomal drugs

The emergence of strains of Schistosoma resistant to praziquantel has drawn attention to the search for new schistosomacide drugs. Imidazolidinic derivatives have performed outstandingly against adult S. mansoni worms when evaluated in vitro. The molecular modification of imidazolidine by way of bioisosteric replacement gives rise to variations in its biological response. This study verifies the potential of substituent groups in the derivatives (Z)3-benzyl-5-(2-fluoro-benzylidene)-imidazolidine-2,4-dione NE4, 3-benzyl-5-(4-chloro-arylazo)-4-thioxo-imidazolidin -2-ona PT5, 3-benzyl-5-(3-fluoro-benzylidene)-1-methyl-2-thioxo-imidazolidin-4-one JT53; 3-benzyl-1-methyl-5-(4-methyl-benzylidene)-2-thioxo-imidazolidin-4-one JT63; 3-benzyl-1-methyl-5-(4-methoxi-benzylidene)-2-thioxo -imidazolidin-4-one JT68; 3-(4-chloro-benzyl)-1-methyl-5-(4-methoxi-benzylidene)-2-thioxo-imidazolidin-4-one JT69; 3-(4-phenyl-benzyl)-1-methyl-5-(4-methoxi-benzylidene)-2-thioxo-imidazolidin-4-one JT72 by determining the viability in vitro of adult S. mansoni worms in the presence of these derivatives. The susceptibility of the worms obtained from mice and kept in culture in the presence of different concentrations was determined by way of schistosomacide kinetic, observed every 24 h over a period of eight days. The results show that the worms were more sensitive to the PT5 derivative at a concentration of 58 microM which killed 100% of the worms after 24 h of contact, also giving rise to alterations in the tegument surface of the worms with the formation of bubbles and peeling. These observations suggest a strong electronic contribution of the arylazo grouping in the biological response.

Influence of maternal schistosomiasis on the immunity of adult offspring mice

Schistosoma mansoni infection modulates the immunity to unrelated antigens in the host. In this study, we have investigated the effect of pregnancy and nursing from schistosomotic mother mice on the immune response to ovalbumin (OA), in adult offspring. Then, newborn mice were divided into four groups: animals born from infected mothers (BIM) suckled by non-infected mothers; animals from non-infected mothers suckled by infected mothers (SIM); and two other groups that were mice born and suckled in infected mothers (BSIM) or non-infected (control) mothers. The adult offspring were immunized with OA plus adjuvant. We compared the OA-specific hypersensitivity reactions (HR), antibodies levels (IgG, IgG2a) and the cytokine production in splenocyte cultures. Remarkable interleukin (IL)-10 synthesis was observed in mice BIM; while the anti-OA antibodies levels and immediate HR were impaired. IL-10 neutralization recovered this suppression. Differently, in mice SIM and BSIM there was an enhancement in the anti-OA humoral response and high IL-2 production, however low level of the IL-10 was detected in mice BSIM. In conclusion, schistosomotic pregnancy provides an immunosuppressive potential, IL-10 dependent, which was sustained throughout adult life. Regardless, suckling by infected mothers induces great responsiveness to an unrelated antigen and repairs the inhibitory potential acquired during prenatal stage.

Effect of Biomphalaria straminea plasma in the phagocytosis of Biomphalaria glabrata hemolymph cells

Mollusc defensive system that discriminates self from non self molecules, include fixed cells that can trap particles like endothelial cells, reticular and pore-cells, and circulating elements (WPW Van Der Knaap & ES Loker 1990 Parasitol Today 6: 175-182). Hemocytes, cells with phagocytic capacity, are determinant elements in the resistance or susceptibility of Biomphalaria snails to the trematoda Schistosoma mansoni infection (FS Bezerra et al. 1997 Rev Inst Med Trop S Paulo 39: 197-201). Biomphalaria resistance or susceptibility to S. mansoni infection is well defined as genetically determined (JV Santana et al. 1978 Rev Saude Publ S Paulo 12: 67-77). Allograft of producing amebocyte organ from resistant snails to susceptible ones, enhance its resistance suggesting that the phenomenon is dependent on hemocytes activity (JT Sullivan et al. 1995 J Parasitol 5: 829-33). On the other hand, inoculation of hemolymph from B. tenagophila infected with either S. mansoni or with other trematoda furcocercaria, raised significantly the cellular response of susceptible mollusc (SM Reis et al. 1995 Rev Saude Publ 29: 259-264). Susceptible B. glabrata snails hemocytes made phagocytosis more efficient when latex particles were covered with resistant strains plasma. Furthermore, the results from our laboratory showed that B. straminea, a highly resistant mollusc to S. mansoni infection, is the only parasite host found in many endemic areas of northeast Brazil [FF Amâncio et al. 1989 Mem Inst Oswaldo Cruz (Suppl. I) 84: 253]. Therefore we tried to observe the influence of soluble products from B. straminea plasma in the phagocytic capacity of B. glabrata hemocytes. B. glabrata hemocyte monolayer was prepared from hemolymph, collected through cephalo-podal bleeding and incubated at 22°C during 40 min in humid chamber. After washing, to remove non adherent cells, the monolayers were incubated with 105 cells of yeast (Saccharomyces sp.) for 1 hr at 22°C. The slides were washed to detach non ingested yeast, fixed with methanol and stained with Giemsa. For determination of the phagocytic index, 200 cells per slide were counted. When necessary, B. straminea plasma was previously incubated with the yeast suspension for 1 hr at 22°C. Another procedure was carried out using the plasma previously warmed at 56°C during half an hour (plasma 56). Following this schedule, five groups were done: Group A: monolayer + fresh B. straminea plasma + yeast suspension Group A 56: monolayer + B. straminea plasma 56 + yeast suspension Group B: monolayer + incubated fresh plasma + yeast suspension Group B 56: monolayer + incubated plasma 56 + yeast suspension Group control: monolayer + Hanks + yeast suspension.

The use of polyvinyl alcohol glutaraldehyde as solid-phase in ELISA for plague

Discs of polyvinyl alcohol cross-linked with glutaraldehyde were synthesized under acid catalysis (H2SO4). Then, the antigen F1 purified from Yersinia pestis was covalently linked to this modified polymer. Afterwards, an enzyme-linked immunosorbent assay (ELISA) was established for the diagnosis of plague in rabbit and human. The best conditions for the method were achieved by using 1.3 micrograms of F1 prepared in 0.067 M phosphate buffer, pH 7.2, containing 1 M NaCl (PBS); anti-IgG peroxidase conjugate diluted 6,000 times and as a blocking agent 3% w/v skim milk in PBS. The titration of positive rabbit serum according to this procedure detected antibody concentrations up to 1:12,800 times. The present method, the conventional ELISA and passive haemagglutination assay are compared.

Perfil protéico e reconhecimento antigênico de extratos de larvas infectantes (L3) de Wuchereria bancrofti

A study of protein characterization and recognition of the antigenic profile was accomplished in extracts of infective larvae (L3) from Wuchereria bancrofti. Two proteins of relative molecular weight of 49 and 55 kDa were recognized as antigenic in all extracts by the tested sera. The secretory/excretory antigen presented the largest number of recognized bands (105, 100, 76, 55, 49, 39 and 32 kDa) followed by the somatic antigen (100, 76, 55 and 49 kDa) when incubated with pools of sera from healthy individuals resident in endemic areas (normal endemics). Human sera and parasitized blood used to infect mosquitoes in order to obtain L3, were collected from microfilaraemic individuals living in a filariasis endemic area. From 792 persons screened with the thick smear technique, 87 (11%) were positive. No statistical significance was observed between genders. The group between 11 and 19 years of age presented higher percentage of infection (36.8%).

The use of ferromagnetic dacron as solid-phase in enzyme immunoassays

Ferromagnetic dacron is proposed as an alternative solid-phase for magnetic enzyme immunoassays. Human serum albumin (HSA) was covalently immobilized onto ferromagnetic dacron and an enzyme immunoassay was developed using anti-HSA rabbit sera. Peroxidase, o-phenylenediamine (OPD) and hydrogen peroxide were used as the enzymatic label and substrates, respectively. Best results were observed when particles of 63-100 microns (diameter) and 10 micrograms of immobilized antigen were used. Positive reactions were detected until dilutions of 1:51200 of immune sera. Its reproducibility was similar to standard ELISA. Disruption of the immunocomplexes formed and recuperation of the immobilized antigen in other immunoassays also proved to be reliable.

Polyvinyl alcohol-glutaraldehyde as solid-phase in Elisa for Schistosomiasis

Soluble adult Schistosoma mansoni antigen preparation (SWAP) was covalently fixed onto polyvinyl alcohol-glutaraldehyde discs and an enzyme linked-immunosorbent assay (ELISA) was set up. The best conditions for the assay were established and it was found that small amount of antigen such as 1.5 micrograms was required. A comparison between this procedure and the conventional ELISA was proceeded. A reliable method of antigen immobilization was achieved and the low prices of the employed reagents are economically attractive.

Características clínicas de 64 indivíduos portadores de uveítis posterior activa presumiblemente toxoplásmica en Pernambuco

PURPOSE: To describe clinical characteristics of posterior active uveitis presumptively by Toxoplasma gondii (PAUPT) in patients with typical lesion. Tranversal study. METHODS: Sixty-four patients with retinochoroiditis scatter and active satellite lesions examined in Pernambuco, Brazil. All were older than 10 years and immunocompetent. Gender, age, skin color, and residence were recorded. Previous uveitis, visual accuracy, intraocular pressure (IOP), and ocular examination were analyzed. RESULTS: 52% were males, most of them with white skin (68.8%). Mean age 29 years (±10.87). Eighty-four percent of the patients lived in the metropolitan area. 56.2% were having the first episode of uveitis. In the damaged eye, visual accuracy mean was 20/200, IOP mean 14.5 mmHg (±64). Hyperemia of the conjunctiva was observed in 29.7% of the patients and alterations of the cornea in 51.6%. There were cells in the aqueous humor in 62.7%. 6.2% had posterior synechiae. All had vitreous damage and 45.3% retinal vasculitis. In 42.2% of the patients, lesions were located in zone I of Holland and 90.6% had the size of one discus diameter or greater. Neuritis was observed in 28.2%. Uveitis was more frequent in the right eye (54.7%). CONCLUSION: PAUPT affects young people and the main symptom was reduction of visual acuity. IOP mean was normal. Alterations of the vitreous were observed in all cases. Injuries were equal to one discus diameter or greater and located in zone I of Holland.

Portadores assintomáticos de infecções por Streptococcus pyogenes em duas escolas públicas na cidade do Recife, Pernambuco

OBJECTIVES: assess the prevalence of Streptococcus pyogenes in throat secretions of students from two public elementary schools in Recife. METHODS: an epidemiological and clinical-microbiological study was performed. From two schools, 753 individuals were examined. Throat secretion cultures were performed in blood sheep agar 5% and SBGA strains identified by bacitracin, Pyr and latex agglutination tests. RESULTS: the school children were aged from five to 19 years old, 54,3% of the sample were male and 45,7% female. Six asymptomatic SBGA carriers were identified. Following treatment with penicillin, ASLO sera titration was performed. All carriers had antibody titers below 200UT. CONCLUSIONS: SBGA prevalence rate of 0,8% was estimated in asymptomatic carriers, this percentage was low when compared with other results from similar studies. The authors suggest that epidemiological studies be accomplished to estimate SBGA prevalence in children with pharyngitis and correlation with acute rheumatic fever.

PREVALENCE OF Entamoeba histolytica/Entamoeba dispar IN THE CITY OF CAMPINA GRANDE, IN NORTHEASTERN BRAZIL

There is a clear need to perform epidemiological studies to find the true prevalence of Entamoeba histolytica around the world. The evaluation of this prevalence has been hindered by the existence of two different species which are morphologically identical, but genetically different, namely E. histolytica, which causes amebiasis, and E. dispar, which is non-pathogenic. In Brazil, the E. dispar has been detected in communities in the Southeastern (SE) and Northeastern (NE) regions with poor sanitation. However, individuals infected with E. histolytica have been identified in other regions. There is an absence of reports on the prevalence of these parasites in the state of Paraíba, which also has areas with poor sanitary conditions where a high prevalence of the E. histolytica/E. dispar complex has been detected in children from urban slums. The present study evaluated the prevalence of E. histolytica and E. dispar in 1,195 asymptomatic children between two and 10 years of age, living in a sprawling urban slum in Campina Grande, in the state of Paraíba, in Northeastern Brazil. These children were examined and their feces samples were analyzed microscopically. A total of 553 children tested positive for the E. histolytica/E. dispar complex, and 456 of the positive samples were tested with the E. histolytica II® ELISA kit. All 456 samples were negative for the presence of the adhesin E. histolytica specific antigen. The evidence suggests that in this community E. histolytica is absent and E. dispar is the dominant species.