WILLIAM HENRY ROLDAN GONZALES
Projetos de Pesquisa
Unidades Organizacionais
LIM/06 - Laboratório de Imunopatologia da Esquistossomose e outras Parasitoses, Hospital das Clínicas, Faculdade de Medicina
6 resultados
Resultados de Busca
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- Diagnostic accuracy of somatic and excretory-secretory antigens from Strongyloides venezuelensis infective larvae for the immunodiagnosis of human strongyloidiasis(2021) GONZALES, William Henry Roldan; MEISEL, Dirce Mary Correia Lima; PAULA, Fabiana Martins de; GRYSCHEK, Ronaldo Cesar BorgesTo evaluate the diagnostic accuracy of three types of antigenic preparations from Strongyloides venezuelensis infective larvae for detection of serum IgG anti-Strongyloides antibodies by enzyme-linked immunosorbent assay (ELISA). Soluble somatic fractions (SSF) and membrane somatic fractions (MSF) and excretory-secretory (E/S) products from S. venezuelensis infective larvae were evaluated against 71 sera from individuals with strongyloidiasis, 105 sera from healthy individuals, and 84 sera from individuals with other helminth infections. Using an ELISA cut-off for 100% sensitivity, E/S products were 97.88% specific followed by MSF (93.12%) and then by SSF (85.2%). The occurrence of cross-reactivity with other helminths was 4.76% (4/84) with E/S products, 8.33% (7/84) with MSF, and 17.86% (15/84) with SSF. For a cut-off for 100% specificity, E/S products showed a sensitivity of 88.73% whereas MSF and SSF showed sensitivities of 59.15% and 53.52%, respectively. In conclusion, E/S products were the best antigenic option for the serodiagnosis of human strongyloidiasis.
- Culture isolation and molecular identification of Blastocystis sp. in Brazilian human isolates: preliminary results(2020) MELO, Gessica Baptista de; ROLDAN, William; MALTA, Fernanda de Mello; LESCANO, Susana Angelica Zevallos; CASTILHO, Vera Lucia; GONCALVES, Elenice Messias Do Nascimento; PAULA, Fabiana Martins de; GRYSCHEK, Ronaldo Cesar BorgesBlastocystis sp. is a protist commonly found in stool samples of humans and animals. Biological and genetic factors of this organism remain controversial. The present study aimed to develop and implement the Blastocystis in vitro culture of Brazilian human isolates for routine use. The fecal isolates (n = 20) were maintained in our laboratory by several passages in Pavlova's medium. Cultures were monitored every 72 h by light microscopy. Genomic DNA was extracted to identify the subtypes (STs). In most isolates, the vacuolar form was prevalent. The amoeboid, granular and cystic forms were observed during in vitro cultivation. STs 1, 2, 3. 4 and 7 were identified. Our preliminary results show the generation time and forms present in the in vitro culture of Blastocystis subtypes isolated from Brazilian human isolates. Therefore, we emphasize the use of in vitro culture as a tool in future studies for the better understanding of the biological aspects of Blastocystis sp.
- A simple method for purification of Strongyloides venezuelensis eggs from rat faeces(2020) ROLDAN, W. H.; PAULA, F. Martins de; GRYSCHEK, R. C. B.The aim of this study was to develop a simple method to purify Strongyloides eggs from rat faeces using a sucrose gradient centrifugal-flotation technique. This procedure is simple, rapid and possesses a high efficiency in recovering Strongyloides eggs without faecal detritus in less than one hour, thus eliminating the use of complex apparatus and different chemical substances. The possibility of working with pure and live Strongyloides eggs opens up a wide range of future studies on the biology of this parasite. This study constitutes the first report in the scientific literature on purifying Strongyloides eggs using a sucrose density gradient.
- Evaluation of larval surface antigens from infective larvae of Strongyloides venezuelensis for the serodiagnosis of human strongyloidiasis(2023) GOMES, Bruna Barroso; GONZALES, William Henry Roldan; MEISEL, Dirce Mary Correa; GRYSCHEK, Ronaldo Cesar Borges; PAULA, Fabiana Martins deSerodiagnosis of strongyloidiasis is usually performed by ELISA for the detection of IgG antibodies due to its high sensitivity and practicality, but its main limitation is a constant source of S. stercoralis antigens. The use of S. venezuelensis as a heterologous source of antigens has facilitated several published studies on the serodiagnosis and epidemiology of human strongyloidiasis. The main objective of this study was to evaluate the diagnostic accuracy of surface cuticle antigens of infective larvae of S. venezuelensis extracted with CTAB detergent (L3-CTAB) in comparison with soluble somatic extracts (L3-SSE) using a panel of sera from immunocompetent and immunocompromised individuals, at three different cut-offs. ROC curve analysis showed that L3-CTAB had an AUC of 0.9926. At the first cut-off value (OD 450 nm = 0.214), sensitivity and specificity were 100% and 90.11%, respectively, with a diagnostic accuracy of 0.93. At a second cut-off value (OD 450 nm = 0.286), sensitivity and specificity were 70% and 100%, respectively, with a diagnostic accuracy of 0.91. However, at an alternative third cut-off value (OD 450 nm = 0.589), sensitivity and specificity were 95% and 97.8%, respectively, with a diagnostic accuracy of 0.97. Using L3-CTAB as an antigenic source, the seropositivity rate in immunocompromised patients was 28.13% (9/32) whereas a seropositivity rate of 34.38% (11/32) was found when L3-SSE was used in ELISA. Therefore, the L3-CTAB is simple and practical to obtain and was found to be highly sensitive and specific.
- Serological diagnosis of strongyloidiasis in immunocompetent and immunosuppressed patients based on an electrochemical immunoassay using a flexible device allied to PLS-DA and ROC statistical tools(2022) MATTOS, Gabriel J.; MARCHEAFAVE, Gustavo G.; ROLDAN, William H.; MATTOS, Miguel J.; PAULA, Fabiana M. de; GRYSCHEK, Ronaldo C. B.; SARTORI, Elen R.Strongyloidiasis is a tropical disease caused by the nematode called Strongyloides stercoralis. An electrochemical immunosensor was efficiently constructed for the diagnosis of this helminthiasis using the larvae epicuticle as the antigen electrostatically immobilized on the surface of a screen-printed electrode, modified with graphene/ ZnOQDs composite. The mechanism of monitoring was based on the changes in the electrochemical parameters of the device due to the antigen-antibody binding on its interface. The immunosensor was characterized using electrochemical impedance spectroscopy and cyclic voltammetry, evaluating the impedimetric/voltammetric biorecognition of the antigen-antibody complex using the redox group K4Fe(CN)6 as the electrochemical probe. This bioelectronic device detected antibodies in positive serum samples based on the voltammetric profile and electrochemical impedance monitoring. Partial least squares-discriminant analysis showed a coefficient of determination of 0.98, indicating that the model can correctly classify samples as positive or negative for strongyloidiasis, based on the voltammetric profile of samples from immunocompetent patients. The analysis of the root mean square error of cross-validation (0.126), the root mean square error of calibration (0.124), and the root mean square error of prediction (0.100) for the latent variable indicate the optimal precision of the model. Based on the receiver operating characteristic curves, the cutoff was determined for the electrochemical impedance measurements, obtaining a 100% correct classification for immunocompetent patients and just 1.25% false-negatives in cases of immunosuppressed patients. The immunosensor presented excellent specificity in the presence of other helminthiases, including ascaridiasis, diphyllobothriasis, himenolepiasis, cysticercosis, and trichuriasis.
- Proteomic analysis of the excretory-secretory products from Strongyloides venezuelensis infective larvae: new insights for the immunodiagnosis of human strongyloidiasis(2022) GONZALES, William Henry Roldan; COELHO, Guilherme Rabelo; PIMENTA, Daniel Carvalho; PAULA, Fabiana Martins de; GRYSCHEK, Ronaldo Cesar BorgesSerodiagnosis of human strongyloidiasis is a practical alternative to parasitological methods due to its high sensitivity. However, cross-reactivity with other helminth infections limits its utility, and this problem is due to the use of homologous or heterologous somatic extracts of the parasite as an antigen source. Excretory-secretory (E/S) products from Strongyloides infective larvae can be used to improve the serodiagnosis. The combined use of western blot and proteomics became an interesting strategy to identify immunological markers for the serodiagnosis of strongyloidiasis. The present study describes the proteomic analysis of the antigenic components from E/S products of S. venezuelensis infective larvae that were recognized by IgG antibodies from patients with strongyloidiasis. Our results showed that IgG antibodies from patients with strongyloidiasis recognized between 15 and 16 antigenic bands in the E/S products from S. venezuelensis that were incubated in PBS or in RPMI culture medium, respectively. Overall, antigenic bands of low and high molecular weight were more specific than those of intermediate molecular weight, which were cross-reactive. A 36-kDa antigenic band was 93% sensitive and 100% specific (a probably arginine kinase of 37 kDa), while other antigenic bands were highly sensitive but low specific. Proteomic analysis revealed differences between the protein profiles from E/S-RPMI and E/S-PBS since only one-third of all proteins identified were common in both types of E/S products. Bioinformatic analysis showed that more than 50% of the proteins from E/S products are secreted within extracellular vesicles and only a small percentage of them are actually released by the classical secretory pathway. Several components from the E/S products were identified as plasminogenbinding proteins, probably used as an immune evasion mechanism. The data provided here provide valuable information to increase understanding of E/S products from S. venezuelensis infective larvae. This may help us to find new targets for the immunodiagnosis of human strongyloidiasis.