ABSTRACT
Listeria monocytogenes is a major intracellular human foodborne bacterial pathogen. We previously revealed L. monocytogenes cadC as highly expressed during mouse infection. Here we show that L. monocytogenes CadC is a sequence-specific, DNA-binding and cadmium-dependent regulator of CadA, an efflux pump conferring cadmium resistance. CadC but not CadA is required for L. monocytogenes infection in vivo. Interestingly, CadC also directly represses lspB, a gene encoding a lipoprotein signal peptidase whose expression appears detrimental for infection. lspB overexpression promotes the release of the LpeA lipoprotein to the extracellular medium, inducing tumor necrosis factor α and interleukin 6 expression, thus impairing L. monocytogenes survival in macrophages. We propose that L. monocytogenes uses CadC to repress lspB expression during infection to avoid LpeA exposure to the host immune system, diminishing inflammatory cytokine expression and promoting intramacrophagic survival and virulence. CadC appears as the first metal efflux pump regulator repurposed during infection to fine-tune lipoprotein processing and host responses.
Subject(s)
Bacterial Proteins/metabolism , Cadmium/metabolism , Host-Pathogen Interactions/genetics , Lipoproteins/metabolism , Listeria monocytogenes/metabolism , Listeria monocytogenes/pathogenicity , Animals , Bacterial Proteins/genetics , Listeria monocytogenes/genetics , Listeriosis/microbiology , Mice , Mice, Inbred C57BL , Peptide Termination Factors/metabolism , Signal Transduction , Virulence Factors/metabolismABSTRACT
PURPOSE: We describe the results of a risk-adapted, response-based therapeutic approach from the Brazilian GCT-99 study on germ cell tumors. PATIENTS AND METHODS: From May 1999 to October 2009, 579 participants were enrolled in the Brazilian GCT-99 study. Treatment, defined as specific chemotherapy regimen and number of cycles, was allocated by means of risk-group assignment at diagnosis with consideration for stage and primary tumor site. Patients at low risk received no chemotherapy. Patients at intermediate risk (IR) with a good response (GR) received four cycles of platinum and etoposide (PE), for total doses of platinum 420 mg/m(2) and etoposide 2,040 mg/m(2). Patients at IR with a partial response (PR) received three cycles of PE plus three cycles of ifosfamide, vinblastine, and bleomycin. Patients at high risk (HR) with a GR received four cycles of PE and ifosfamide (PEI) at total doses of platinum 420 mg/m(2), etoposide 1,200 mg/m(2), and ifosfamide 30 g/m(2). Patients at HR with a PR received six cycles of PEI. RESULTS: The risk-group distribution was 213 LR, 138 IR, and 129 HR for 480 evaluable patients. Overall survival (OS) and event-free survival (EFS) rates at 10 years were, respectively, 90% and 88.6% in the IR-GR group (n = 126) and 74.1% and 74.1% in the IR-PR group (n = 12). Ten-year rates for the HR-GR group (n = 86) were an OS of 66.8% and an EFS of 62.5%. The HR-PR group (n = 43) had an OS of 74.8% and an EFS of 73.4%. In univariable and multivariable analysis, increased serum lactate dehydrogenase level and histology for a metastatic immature teratoma were prognostic of a worsened outcome. CONCLUSION: Reduction of therapy to two drugs did not compromise survival outcomes for patients in the IR-GR group, and escalation of therapy with PEI did not significantly improve OS and EFS in patients at HR.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Bleomycin , Cisplatin/administration & dosage , Head and Neck Neoplasms/drug therapy , Mediastinal Neoplasms/drug therapy , Neoplasms, Germ Cell and Embryonal/drug therapy , Ovarian Neoplasms/drug therapy , Retroperitoneal Neoplasms/drug therapy , Testicular Neoplasms/drug therapy , Vaginal Neoplasms/drug therapy , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Brazil , Child , Disease-Free Survival , Etoposide/administration & dosage , Female , Humans , Ifosfamide/administration & dosage , Male , Neoplasms, Germ Cell and Embryonal/pathology , Risk Assessment , Survival Rate , Vinblastine/administration & dosageABSTRACT
BACKGROUND: Childhood cancer is relatively rare and tends to present specific age distribution, as a prognostic factor for some of these diseases. Information on how young age affects prognosis, response to chemotherapy, and local control options in children versus AYA with osteosarcoma (OST) is minimal. METHODS: In order to identify the main differences in clinical pathologic features, surgical approaches and survival rates of primary high grade OST of the extremity between children (n = 156; <12 years old) and AYA (n = 397; 12-30 years old), the institutional database with 553 patients treated by BOTG studies over 15 years were reviewed. RESULTS: There were no differences in metastases at diagnosis, tumor size, and grade of necrosis between the two age groups. The rate of amputation was 30% higher in the children group (P = 0.018). The rate of limb salvage surgery using reconstruction with allograft or autograft was 70% higher in the children group (P = 0.018) while endoprosthesis rate was 40% higher in the AYA group (P = 0.018). The log rank test revealed that survival is similar between the two age groups for non-metastatic patients (P = 0.424 for OS and P = 0.393 for EFS). Metastatic patients of both ages group had higher risk of dying compared to non-metastatic (HR 3.283 95% CI 2.581-4.177; P < 0.001). Children with metastases at diagnosis had less OS time (P = 0.049) and EFS time (P = 0.032) than adolescents. CONCLUSION: Non-metastatic OST in preadolescent patients does not appear to be significantly different from those seen in AYA patients, but has local control challenges. Children presenting with metastases should be considered an ultra-high-risk group.
Subject(s)
Bone Neoplasms/pathology , Extremities/pathology , Neoplasm Recurrence, Local/pathology , Osteosarcoma/secondary , Adolescent , Adult , Age Factors , Bone Neoplasms/mortality , Bone Neoplasms/surgery , Child , Child, Preschool , Extremities/surgery , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Male , Neoplasm Recurrence, Local/mortality , Neoplasm Recurrence, Local/surgery , Neoplasm Staging , Osteosarcoma/mortality , Osteosarcoma/surgery , Prognosis , Survival Rate , Young AdultABSTRACT
Bacterial pathogens often interfere with host tyrosine phosphorylation cascades to control host responses and cause infection. Given the role of tyrosine phosphorylation events in different human infections and our previous results showing the activation of the tyrosine kinase Src upon incubation of cells with Listeria monocytogenes, we searched for novel host proteins undergoing tyrosine phosphorylation upon L. monocytogenes infection. We identify the heavy chain of the non-muscle myosin IIA (NMHC-IIA) as being phosphorylated in a specific tyrosine residue in response to L. monocytogenes infection. We characterize this novel post-translational modification event and show that, upon L. monocytogenes infection, Src phosphorylates NMHC-IIA in a previously uncharacterized tyrosine residue (Tyr-158) located in its motor domain near the ATP-binding site. In addition, we found that other intracellular and extracellular bacterial pathogens trigger NMHC-IIA tyrosine phosphorylation. We demonstrate that NMHC-IIA limits intracellular levels of L. monocytogenes, and this is dependent on the phosphorylation of Tyr-158. Our data suggest a novel mechanism of regulation of NMHC-IIA activity relying on the phosphorylation of Tyr-158 by Src.
Subject(s)
Listeria monocytogenes/physiology , Listeriosis/enzymology , Nonmuscle Myosin Type IIA/metabolism , Protein Processing, Post-Translational , src-Family Kinases/metabolism , Amino Acid Sequence , Bacterial Load , Caco-2 Cells , Enzyme Activation , HeLa Cells , Host-Pathogen Interactions , Humans , Listeriosis/microbiology , PhosphorylationABSTRACT
In the heterogeneous semi-solid environment naturally occupied by lignocellulolytic fungi the majority of nutrients are locked away as insoluble plant biomass. Hence, lignocellulolytic fungi must actively search for, and attach to, a desirable source of nutrients. During growth on lignocellulose a period of carbon deprivation provokes carbon catabolite derepression and scavenging hydrolase secretion. Subsequently, starvation and/or contact sensing was hypothesized to play a role in lignocellulose attachment and degradation. In Aspergillus nidulans the extracellular signalling mucin, MsbA, influences growth under nutrient-poor conditions including lignocellulose. Cellulase secretion and activity was affected by MsbA via a mechanism that was independent of cellulase transcription. MsbA modulated both the cell wall integrity and filamentous growth MAPK pathways influencing adhesion, biofilm formation and secretion. The constitutive activation of MsbA subsequently enhanced cellulase activity by increasing the secretion of the cellobiohydrolase, CbhA, while improved substrate attachment and may contribute to an enhanced starvation response. Starvation and/or contact sensing therefore represents a new dimension to the already multifaceted regulation of cellulase activity.
ABSTRACT
PURPOSE: Little information is available regarding the tumor features, prognostic factors, and treatment results in children and adolescents and young adults (AYAs) with osteosarcoma diagnosed in developing countries. We reviewed the results of three observational cohorts of osteosarcoma patients treated in an emerging country. METHODS: A total of 604 patients below the age of 30 years with high-grade osteosarcoma were prospectively enrolled in the Brazilian Osteosarcoma Treatment Group (BOTG) studies III, IV, and V. Gender, age, time from onset of symptoms to diagnosis, primary tumor site, presence or absence of metastases at diagnosis, tumor size, type of surgery (limb-sparing or amputation), treatment protocol, and histological response were correlated with survival. RESULTS: The estimated 5-year overall survival and event-free survival (EFS) rates for the 553 eligible patients were 49% and 39% respectively; of the 390 non-metastatic patients included in the total, overall- and event-free survival were 59% and 48% respectively. Metastases at diagnosis, primary tumor site, type of surgery, and histological response were significant predictors of overall survival and EFS in univariate and multivariate analysis, whereas tumor size and treatment protocol lost prognostic significance in multivariate analysis. CONCLUSION: We report on the outcome of three consecutive studies for the treatment of osteosarcoma carried out in Brazil over 15 years. Although the survival rates presented are below those reported in current literature, it represents the result of a favorable experience gathered from the national collaborative work.
ABSTRACT
Listeria monocytogenes is an intracellular food-borne pathogen causing listeriosis in humans. This bacterium deploys an arsenal of virulence factors that act in concert to promote cellular infection. Bacterial surface proteins are of primary importance in the process of host cell invasion. They interact with host cellular receptors, inducing/modulating specific cellular responses. We previously identified Vip, a Listeria surface protein covalently attached to the bacterial cell wall acting as a key virulence factor. We have shown that Vip interacts with Gp96 localized at the surface of host cells during invasion and that this interaction is critical for a successful infection in vivo. To better understand the importance of Vip-Gp96 interaction during infection, we aimed to characterize this interaction at the molecular level. Here we demonstrate that, during infection, L. monocytogenes triggers the cellular redistribution of Gp96, inducing its exposure at the cell surface. Upon infection, Gp96 N-terminal domain is exposed to the extracellular milieu in L2071 fibroblasts and interacts with Vip expressed by Listeria. We identified Gp96 (Asp(1)-Leu(170)) as sufficient to interact with Vip; however, we also showed that the region Tyr(179)-Leu(390) of Gp96 is important for the interaction. Our findings unravel the Listeria-induced surface expression of Gp96 and the topology of its insertion on the plasma membrane and improve our knowledge on the Vip-Gp96 interaction during Listeria infection.
Subject(s)
Cell Membrane/metabolism , Listeria monocytogenes/physiology , Listeriosis/metabolism , Listeriosis/microbiology , Membrane Glycoproteins/chemistry , Membrane Glycoproteins/metabolism , Animals , Antibodies/pharmacology , Bacterial Proteins/metabolism , Caco-2 Cells , Cell Membrane/drug effects , Humans , Listeria monocytogenes/drug effects , Membrane Glycoproteins/genetics , Membrane Glycoproteins/immunology , Mice , Protein Binding/drug effects , Protein Structure, TertiaryABSTRACT
Hidradenoma papilliferum is a rare tumor that occurs almost exclusively in females on the anogenital area. Rare cases of ectopic (nongenital) hidradenoma papilliferum have been described. The lesions usually present as an asymptomatic slow-growing, red, firm, mobile, well-delimitated nodule that grows for a long time before resection. We describe a case of an 26-year-old man that presented with an enlarging nodule on his right eyelid. The histological findings revealed a hidradenoma papilliferum. So far, among the very few reports of ectopic hidradenoma papilliferum, only a very small number were localized to the eyelid.
ABSTRACT
PURPOSE: In 1988, we formed a consortium of Brazilian institutions to develop uniform standards for the diagnostic assessment and multidisciplinary treatment of children and adolescents with germ cell tumors. We also implemented the first childhood Brazilian germ cell tumor protocol, GCT-91, evaluating two-agent chemotherapy with cisplatin and etoposide (PE). We now report on the clinical characteristics and survival of children and adolescents with germ cell tumors treated on this protocol. PATIENTS AND METHODS: From May 1991 to April 2000, 115 patients (106 assessable patients) were enrolled onto the Brazilian protocol with a diagnosis of germ cell tumor. RESULTS: Patients were treated with surgery only (n = 35) and chemotherapy (n = 71). Important prognostic factors included stage (P = .025), surgical procedure at diagnosis according to resectability (P < .032), and abnormal lactate dehydrogenase value at diagnosis (P < .001). CONCLUSION: The improvement in survival by the introduction of a standard protocol is an important achievement. This is of particular importance for smaller institutions with previous limited experience in the treatment of childhood germ cell tumors. In addition, the results of a two-agent regimen with PE were favorable (5-year overall survival rate is 83.3% for patients in the high-risk group [n = 36] who received PE v 58.8% for patients in the high-risk patients group who received PE plus ifosfamide, vinblastine, and bleomycin [n = 17; P = .017]). Thus for selected patients, complex three-agent regimens may not be necessary to achieve long-term survival, even for some patients with advanced disease.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Neoplasms, Germ Cell and Embryonal/drug therapy , Adolescent , Child , Child, Preschool , Cisplatin/administration & dosage , Etoposide/administration & dosage , Female , Humans , Infant , Infant, Newborn , Male , Neoplasms, Germ Cell and Embryonal/mortality , Survival RateABSTRACT
Amostras da hortaliça alface, pronta para consumo e sem adição de temperos, foram obtidas de sete restaurantes de padrão self-service, que servem refeição por quilograma. O total de 35 amostras foi coletado em dias alternados e diretamente do balcão de distribuição desses restaurantes na cidade de Limeira-SP. As amostras foram analisadas com o objetivo de conhecer as condições microbiológicas de hortaliças folhosas cruas servidas em locais de mesmo padrão. Para a realização das análises foram estabelecidos parâmetros microbiológicos, considerando a pesquisa das seguintes bactérias: coliformes totais, coliformes a 45°C, Salmonella spp, contagem total de aeróbios mesófilos e Saphylococcus coagulase positiva. Os resultados foram bastante heterogêneos, com grande variação nas contagens para coliformes totais, coliformes a 45°C, e números elevados nas contagens de aeróbios mesófilos. (...) Pelos resultados obtidos, considera-se que há falhas decorrentes de práticas inadequadas de manipulação com ausência ou deficiência de sanificação, sendo necessário treinamento de funcionários e proprietários dos locais, visando correção dos problemas, para que se obtenha a qualidade microbiológica adequada do produto e assegure a saúde do consumidor.
Subject(s)
Lactuca/microbiology , Coliforms , Food Analysis , Food Contamination , Food Hygiene , Food Microbiology , Restaurants , Brazil , Consumer Product SafetySubject(s)
Humans , Female , Pregnancy , Maternal Mortality , Pregnancy Complications , Brazil , Socioeconomic FactorsABSTRACT
O objetivo deste trabalho foi identificar óbitos de mulheres em idade reprodutiva durante o ciclo gravídico-puerperal ampliado, de forma a contribuir para as ações de vigilância da mortalidade materna. Para identificação de mortes durante o ciclo gravídico-puerperal foi feita busca de evento característico deste ciclo gravídico-puerperal para as mulheres que faleceram em idade reprodutiva, por meio de relacionamentos probabilísticos dos registros dos óbitos de mulheres de 10 a 49 anos informados no Sistema de Informações sobre Mortalidade (SIM), com os registros das seguintes bases de dados: internações hospitalares de mulheres do mesmo grupo de idade registradas no Sistema de Internação Hospitalar (SIH-SUS); óbitos fetais e de menores de 1 ano, também originadas do SIM; e registros de nascidos vivos do Sistema de Informações sobre Nascidos Vivos (SINASC). O processo de relacionamento probabilístico de registros foi utilizado o aplicativo Reclink. A identificação de mortes durante o ciclo gravídico-puerperal foi possível pelo relacionamento probabilístico das bases de dados. Este processo resultou em ganhos para a vigilância da mortalidade materna não somente pela identificação de óbitos não notificados, mas também pela avaliação de informações relativas à mulher e à assistência a ela prestada, que podem contribuir para subsidiar a implementação de ações voltadas para área de saúde da mulher.
Subject(s)
Female , Humans , Databases as Topic , Information Systems , Maternal Mortality , Models, StatisticalABSTRACT
PURPOSE: To evaluate the impact of chemotherapy and surgery on the outcome of osteosarcoma (OS) of the extremities and to identify prognostic factors in Brazilian patients. PATIENTS AND METHODS: A total of 225 patients with metastatic and nonmetastatic OS of the extremities were enrolled and assessed in two consecutive studies designed and implemented by the Brazilian Osteosarcoma Treatment Group. RESULTS: The 5-year survival and event-free survival rates for the 209 assessable patients were 50.1% and 39%, respectively; for the 178 patients with nonmetastatic disease at diagnosis, the rates were 60.5% and 45.5%, respectively. The multivariate analysis showed that the following variables were associated with a shorter survival: metastases at diagnosis (P < .001), necrosis grades 1 and 2 (P = .046), and tumor size (P = .0071). CONCLUSION: The overall 5- and 10-year survival rates were lower than the rates reported in North American and European trials. A pattern of advanced disease at diagnosis was often present, with a high proportion of patients having metastases (20.8%) and large tumor size (42.9%). However, these features were not necessarily associated with longer duration of prediagnostic symptoms. These findings were considered in the strategic planning of the current Brazilian cooperative study, with the aim of improving survival and quality of life of a large number of patients with OS.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Bone Neoplasms/drug therapy , Bone Neoplasms/surgery , Orthopedic Procedures , Osteosarcoma/drug therapy , Osteosarcoma/surgery , Adolescent , Amputation, Surgical , Bone Neoplasms/pathology , Brazil , Carboplatin/administration & dosage , Chemotherapy, Adjuvant , Child , Cisplatin/administration & dosage , Disease-Free Survival , Doxorubicin/administration & dosage , Epirubicin/administration & dosage , Female , Humans , Ifosfamide/administration & dosage , Limb Salvage , Lung Neoplasms/drug therapy , Lung Neoplasms/secondary , Lung Neoplasms/surgery , Male , Methotrexate/administration & dosage , Multivariate Analysis , Orthopedic Procedures/methods , Osteosarcoma/secondary , Predictive Value of Tests , Prognosis , Proportional Hazards Models , Prospective Studies , Risk Factors , Survival Analysis , Treatment OutcomeABSTRACT
Comparar os resultados terapeuticos dos tres protocolos consecutivamente utilizados pelo Grupo Brasileiro para o Tratamento de Leucemias da Infancia em leucemia linfocitica aguda(LLA) pediatrica, especialmente...
Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Cytarabine , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Risk Assessment , Central Nervous System Neoplasms , Child , Clinical Protocols , Health Care Costs , Medically Underserved Area , Recurrence , Disease-Free Survival , Testicular NeoplasmsABSTRACT
Amifostine protects normal tissue from the cytotoxic damage induced by radiation and chemotherapy. In this study, 39 consecutive newly diagnosed children with osteosarcoma were assessed; 20 received amifostine and 19 did not. The chemotherapy regimen included an induction phase of three cycles of cisplatin (100 mg/m2), carboplatin (500 mg/m2), and doxorubicin (60 mg/m2), followed by surgery. Alternating cycles of cisplatin/ifosfamide (9 mg/m2), ifosfamide/doxorubicin, carboplatin/doxorubicin, and ifosfamide/carboplatin were administered every 3 weeks to complete 26 weeks of treatment. Amifostine was administered 15 minutes before the infusions of cisplatin and carboplatin in a total of 193 infusions. Side effects during infusions and renal, hearing, and bone marrow toxicities were evaluated and compared between the two groups. Hypotension was observed in 28 (14.5%) infusions. No patient required discontinuation of therapy. Fewer than two episodes of vomiting occurred in 130 (71%) infusions and two to five episodes occurred in 51 (28%) infusions, and no patient had grade 4 toxicity. There was no difference between the two groups regarding renal toxicity (creatinine clearance). Neutropenia and leukopenia were significantly less frequent in the amifostine group. No difference was observed in platelet and hearing toxicities. Amifostine was well tolerated in doses of 740 mg/m2 in children and adolescents, and myelotoxicity was less severe in the amifostine group. This was a pilot study for further evaluation in a larger randomized trial.
Subject(s)
Amifostine/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Bone Neoplasms/drug therapy , Osteosarcoma/drug therapy , Radiation-Protective Agents/therapeutic use , Adolescent , Adult , Bone Neoplasms/pathology , Bone Neoplasms/surgery , Carboplatin/administration & dosage , Carboplatin/adverse effects , Child , Child, Preschool , Cisplatin/administration & dosage , Cisplatin/adverse effects , Doxorubicin/administration & dosage , Doxorubicin/adverse effects , Female , Humans , Ifosfamide/administration & dosage , Ifosfamide/adverse effects , Leukopenia/chemically induced , Male , Neutropenia/chemically induced , Osteosarcoma/pathology , Osteosarcoma/surgery , Pilot Projects , Treatment OutcomeABSTRACT
Tres meses apos a campanha de vacinacao em massa (cobertura: 100 por cento, faixa etaria: 9 meses a 14 anos) contra o sarampo, um inquerito soroepidemiologico foi realizado em estudantes de um a 19 anos de idade no municipio de Niteroi, estado do Rio de Janeiro. Amostras sanguineas foram testadas para deteccao de anticorpos especificos contra o sarampo por ensaio imunoenzimatico (EIE), e os casos negativos testados outra vez utilizando-se a reacao de inibicao da hemaglutinacao (IH) e a neutralizacao por reducao de placas (NP)...
Subject(s)
Humans , Infant , Child, Preschool , Child , Adolescent , Immunization Programs/trends , Measles/prevention & control , Morbidity Surveys , Brazil , Measles/epidemiology , Measles/immunologyABSTRACT
From March 1991 to April 1992, 250 measles suspected cases were studied in the Municipality of Niterói, State of Rio de Janeiro. The median age found was 11 years and 76.0 per cent of the cases were in school age children. Exposure histories were present in 149 patients and schools were the most frequent sites of transmission (45.0 per cent). Vaccination status was known for 127 studied cases and 76.4 per cent of them had received measles vaccine before their first birthday. One or more complications were reported for 68 cases and in 8.9 per cent of the studied cases hospitalization was required. Frequency of complications varied according to each age group studied and were more commonly encountered among children < 1 year of age (55.6 per cent). The history of previous vaccination did not diminish the number of complications of the cases studied. The results of this work show changes in age distribution of measles leading to sizeable outbreaks among teenagers and young adults.
Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Adolescent , Adult , Measles Vaccine/immunology , Measles/epidemiology , Disease Outbreaks/statistics & numerical data , Age Distribution , Brazil/epidemiology , Chi-Square Distribution , Incidence , Measles/complications , Measles/prevention & controlABSTRACT
Com o objetivo de estudar o comportamento dos anticorpos contra o sarampo após a vacinaçäo, 684 crianças foram divididas em 4 grupos: Grupo A (341 crianças vacinadas abaixo de um ano de idade); Grupo B (101 crianças com um ano de idade); Grupo C 79 crianças com 2 doses, uma abaixo de um ano e outra com um ano de idade); Grupo D (163 crianças näo vacinadas com história prévia de sarampo - grupo controle). Verificou-se que as crianças do Grupo A apresentavam baixas taxas de anticorpos protetores, sendo que em 25,9 por cento delas, na faixa etária de menores de dois anos, tais anticorpos näo foram detectados, contra nenhum caso do Grupo C e 4,0 por cento do Grupo B. As médias geométricas dos títulos de anticorpos HI do Grupo A foram inferiores às encontradas para os outros grupos. A idade da vacinaçäo foi o fator de maior influência nos resultados deste estudo
Subject(s)
Infant , Child, Preschool , Humans , Antibodies, Viral/blood , Immunization Schedule , Measles Vaccine/immunology , Measles virus/immunology , Aging/immunology , Brazil , Chi-Square Distribution , Dose-Response Relationship, Immunologic , Hemagglutination Inhibition Tests/statistics & numerical data , Neutralization Tests/statistics & numerical dataABSTRACT
No presente trabalho, são descritas as diferentes técnicas segundo as quais se programam esquemas múltiplos de reforçamento e as diferentes metodologias empregadas para a avaliação do fenômeno de contraste comportamental. São, também, diferenciadas formas sob as quais o efeito de contraste comportamental se apresenta. Além disto, são abordadas três das principais teorias para explicação deste fenômeno, sendo avaliada a contribuição de cada uma delas para sua compreensão. Conclui-se que todas essas teorias encontram dados que as fundamentam e são, aparentemente, importantes. Mas talvez seja mais adequado limitar a aplicação de cada uma delas a uma das formas sob as quais o efeito de contraste positivo se manifesta. Diante da impossibilidade de uma afirmativa neste sentido, torna-se necessária a realização de experimentos mais analíticos que revelem, inequivocamente, a contribuição específica de cada uma destas teorias para as diferentes manifestações comportamentais que são englobadas sob o rótulo comum de contraste positivo(AU)