Influence of learning styles on student performance in self-instructional courses.

This study aimed to analyze the learning style of dentistry students in self-instructional courses to assist in pedagogical planning and to choose the most appropriate educational resources for the students' learning profile. A sample of 122 students who responded to the Learning Styles Questionnaire was analyzed. For statistical purposes, correlation analysis, chi-square test, odds ratio, and Student's t-test were performed. In the analyzed sample, there was a higher prevalence of students in the theoretical and reflector styles, and a lower prevalence of students in the activist and pragmatic styles. An analysis of educational resources demonstrated the predominance of theoretical and reflective content. The data show a statistically significant reduction of about 74% in the chances of passing for the activist-pragmatists group compared to other students (χ2(1, N = 122) = 5.795, p < 0.05, odds ratio = 0.26). On the other hand, reflector students who exhibited a lower preference for the activist style had a higher chance of course completion, with a 3.33-fold increase in the likelihood of passing the course (χ2(1, N = 122) = 5.637, p < 0.05, odds ratio = 3.33). These findings highlight the importance of considering students' learning styles in educational planning and resource selection to optimize student performance. Further research is warranted to explore the implications of these findings and to investigate additional factors that may influence student success in self-instructional courses.

Performance of Preventive Methods Applied to the Occlusal Surface of Primary Teeth: A Randomized Clinical Study

Objective: To evaluate the clinical performance of three preventive materials on the occlusal surfaces of primary molars over a 36-month period. Material and Methods: The study was conducted with a split-mouth design involving four experimental groups: G1 ­ resin-modified glass ionomer cement (Vitremer®); G2 - resin sealant (Alpha Seal Light®); G3 - silver diamine fluoride (Cariostatic®); and G4 - control group without material. Thirty-two children aged 36 to 60 months, attending a pediatric clinic, with a deft index ≥ 1 and four primary second molars participated in the study. The material retention was evaluated in G1 and G2, and the presence of incipient caries was evaluated in all groups. Data were submitted to the Wilcoxon test and survival test (α = 5%). Results: At three, six, 12, 24 and 36 months, G2 exhibited greater material loss (maximum loss: 44%) in comparison to G1 (maximum loss: 35%), but this difference did not achieve statistical significance (p = 0.214). The highest incidence of incipient caries occurred in G3 (20%), but no significant differences were found between groups at any evaluation time (p = 0.154). Conclusion: There were no statistically significant differences between the evaluated products regarding material retention and dental caries, although there was more material loss in teeth that received the Alpha Seal® sealant resin, and a greater number of carious lesions in the Cariostatic® group (silver diamine fluoride).

Pacifier-sucking habit duration and frequency on occlusal and myofunctional alterations in preschool children.

The objective of this study was to evaluate the association of pacifier-sucking habit with occlusal and oral myofunctional alterations in preschool children. Eighty-four 2- to 5-year-old children participated in the study. Data on duration and frequency of pacifier use were collected from parents or guardians. Occlusal and oral myofunctional characteristics were examined by a dentist and a speech therapist, respectively. Chi-square tests and Poisson regression were used to analyze the data. The occlusal characteristics that were significantly associated with a pacifier-sucking habit were anterior open bite, altered canine relation, posterior crossbite, increased overjet, and malocclusion. The oral myofunctional characteristics that were significantly associated with a pacifier-sucking habit were resting lip position, resting tongue position, shape of the hard palate, and swallowing pattern. The strongest associations were for anterior open bite (prevalence ratio [PR] = 11.33), malocclusion ( PR = 2 .33), altered shape of the hard palate ( PR = 1.29), and altered swallowing pattern (PR = 1.27). Both duration and frequency of pacifier-sucking habit were associated with occlusal and oral myofunctional alterations. These results emphasize the need for pediatric dentists to advise parents and caregivers about the risks of prolonged pacifier use and refer children to professionals for multidisciplinary assistance to minimize these risks whenever necessary.

Esporte e escola: ferramenta para avaliar a qualidade das atividades extracurriculares em instituições de ensino / Sports and school: tool to evaluate the quality of extracurricular activities in educational institutions

O objetivo deste trabalho foi avaliar o esporte como serviço, enquanto atividade extracurricular oferecida por uma instituição particular de ensino básico da cidade de São Paulo, utilizando um instrumento já muito conhecido na área da administração, o SERVQUAL. A partir da opinião dospais (responsáveis pelo pagamento do serviço) de alunos regularmente matriculados nas atividadesesportivas extracurriculares, os resultados permitiram diagnosticar as necessidades de melhorias quanto ao serviço que é oferecido pela instituição de ensino. Concluiu-se que o SERVQUAL pode ser útil para os profissionais de educação física que coordenam atividades esportivas extracurriculares.

The aim of this study was to evaluate the sport as a service while extracurricular activity offered bya private Primary School in the city of São Paulo, using the well-known Administration tool, SERVQUAL. From the opinion of parents (liable to pay service) of students enrolled inextracurricular sports activities, the results helped diagnose the needs for improvement regarding the service that is offered by the educational institution. We have concluded that SERVQUAL canbe useful for Physical Education professionals who coordinate extracurricular sports activities.

El objetivo de este trabajo fue evaluar el deporte como servicio, como actividad extracurricular ofrecida por una institución particular de la enseñanza básica de la ciudad de São Paulo, utilizando un instrumento muy conocido en el área de la administración, el SERVQUAL. A partir de la opiniónde los padres (responsables por el pago del servicio) de alumnos regularmente matriculado en las actividades deportivas extracurriculares, los resultados permitieron diagnosticar las necesidades de mejorías con relación al servicio ofrecido por la institución de enseñanza. Se concluyó que elSERVQUAL puede ser útil para los profesionales de educación física que coordinan actividades deportivas extracurriculares.

Pacifier-sucking habit duration and frequency on occlusal and myofunctional alterations in preschool children

The objective of this study was to evaluate the association of pacifier-sucking habit with occlusal and oral myofunctional alterations in preschool children. Eighty-four 2- to 5-year-old children participated in the study. Data on duration and frequency of pacifier use were collected from parents or guardians. Occlusal and oral myofunctional characteristics were examined by a dentist and a speech therapist, respectively. Chi-square tests and Poisson regression were used to analyze the data. The occlusal characteristics that were significantly associated with a pacifier-sucking habit were anterior open bite, altered canine relation, posterior crossbite, increased overjet, and malocclusion. The oral myofunctional characteristics that were significantly associated with a pacifier-sucking habit were resting lip position, resting tongue position, shape of the hard palate, and swallowing pattern. The strongest associations were for anterior open bite (prevalence ratio [PR] = 11.33), malocclusion (PR = 2.33), altered shape of the hard palate (PR = 1.29), and altered swallowing pattern (PR = 1.27). Both duration and frequency of pacifier-sucking habit were associated with occlusal and oral myofunctional alterations. These results emphasize the need for pediatric dentists to advise parents and caregivers about the risks of prolonged pacifier use and refer children to professionals for multidisciplinary assistance to minimize these risks whenever necessary.

Morphometric evaluation of condylar cartilage of growing rats in response to mandibular retractive forces.

INTRODUCTION: The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. OBJECTIVE: The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. METHODS: Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 measurements for each parameter of each animal. RESULTS: The greatest difference in cartilage thickness was observed in 21 days, although different levels were observed in the other periods. Group E showed an increase of 39.46% in the total layer, reflected by increases in the thickness of the hypertrophic (42.24%), hyaline (46.92%) and proliferative (17.70%) layers. CONCLUSIONS: Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.

Morphometric evaluation of condylar cartilage of growing rats in response to mandibular retractive forces

INTRODUCTION: The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. OBJECTIVE: The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. METHODS: Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 measurements for each parameter of each animal. RESULTS: The greatest difference in cartilage thickness was observed in 21 days, although different levels were observed in the other periods. Group E showed an increase of 39.46% in the total layer, reflected by increases in the thickness of the hypertrophic (42.24%), hyaline (46.92%) and proliferative (17.70%) layers. CONCLUSIONS: Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.

INTRODUÇÃO: a superfície do côndilo da mandíbula é constituída por quatro camadas: uma externa (constituída de tecido conjuntivo denso), seguida pela camada de células indiferenciadas, cartilagem hialina e osso. Poucos estudos demonstraram o comportamento da cartilagem condilar quando a mandíbula é posicionada posteriormente, como na terapia para correção de Classe III funcional. OBJETIVO: o objetivo desse trabalho foi avaliar os aspectos morfológicos e histológicos do côndilo de ratos, em resposta ao posicionamento posterior da mandíbula. MÉTODOS: foram selecionados 30 ratos Wistar, machos, com cinco semanas de vida, aleatoriamente divididos em dois grupos: grupo controle (GC) e grupo experimental (GE), que recebeu dispositivos para induzir a retrusão mandibular. Os animais foram sacrificados após 7, 21 e 30 dias de experimento. Para a análise histológica, foi realizada a mensuração da espessura condilar total, incluindo as camadas proliferativa, seriada e hipertrófica, assim como cada camada separadamente, totalizando 30 medições para cada parâmetro, de cada animal. RESULTADOS: a maior diferença na espessura da cartilagem foi observada em 21 dias, apesar de serem verificados níveis diferentes nos demais períodos. Em GE, foi possível observar um aumento de 39,46% na camada total, representado pelo aumento na espessura das camadas hipertrófica (42,24%), seriada (46,92%) e proliferativa (17,70%). CONCLUSÕES: o reposicionamento posterior da mandíbula produziu uma série de respostas histológicas e morfológicas no côndilo, e sugerem a ocorrência de uma adaptação condilar e mandibular em ratos.

Colesteatoma primário de meato acústico externo bilateral / Primary cholesteatoma of the bilateral external acoustic meatus

Introdução: O colesteatoma de meato acústico externo é uma patologia rara. A maioria das séries na literatura descreve casos secundários, com poucos relatos de colesteatoma primário. Caracteriza-se pela erosão da porção óssea do meato acústico externo por proliferação de tecido escamoso adjacente. Objetivo: Relatar um caso raro de colesteatoma primário de meato acústico externo bilateral. Relato do Caso: Paciente de 20 anos, sexo feminino, com otalgia há 3 anos, associada à hipoacusia e otorreia à esquerda. Sem história prévia de patologias otológicas. À otoscopia, observava-se erosão bilateral do meato acústico externo com grande quantidade de debris epidérmicos. A tomografia computadorizada evidenciou colesteatoma de meato acústico externo bilateral, sendo a paciente submetida à timpanomastoidectomia radical modificada à direita. Comentários Finais: O colesteatoma primário de meato acústico externo é uma patologia rara, fazendo parte do diagnóstico diferencial de otalgia e otorreia crônicas. A avaliação da sua extensão deve ser feita com tomografia computadorizada e o tratamento de eleição é a cirurgia.

Introduction: The cholesteatoma of the external acoustic meatus is an uncommon pathology. Most series in the literature describe secondary cases, with a few reports of primary cholesteatoma. It is characterized by the erosion of the external acoustic meatus bone portion by proliferation of the adjacent squamous tissue. Objective: To report an uncommon case of primary cholesteatoma of the bilateral external acoustic meatus. Case Report: Female patients aged 20 years old with ear ache for 3 years, associated to hypacusis and otorrhea to the left. Without a previous history of otologic pathologies. Upon otoscopy, there could be noticed bilateral erosion from the external acoustic meatus with a large amount of epidermal debris. The computed tomography confirmed cholesteatoma of the bilateral external acoustic meatus and the patient was submitted to modified radical tympanomastoidectomy to the right. Final Comments: The primary cholesteatoma of the external acoustic meatus is an uncommon pathology that is part of the differential diagnosis of chronic otalgia and otorrhea. The evaluation of its extension must be done with computed tomography and surgery is the choice treatment.

Solar disinfection for the post-treatment of greywater by means of a continuous flow reactor.

SODIS (solar disinfection) is a low-cost alternative for water decontamination. The method is based on the exposure of water, contained in PET bottles, to direct sunlight, and mainly its UV-A and infrared components. The present research studied SODIS as a low cost alternative for the inactivation of Escherichia coli (E. coli) in treated greywater, aiming at its reuse for more noble applications. Experiments were performed in (i) batch mode (2 L PET-bottles), testing the effect of turbidity on system efficiency and, (ii) in a continuous pilot-scale reactor prototype (51 L, using interconnected 2 L-PET bottles), testing hydraulic retention times (HRT) of 18 and 24 h. Samples were exposed to an average solar radiation intensity of 518 W/m2. The results obtained indicate that the SODIS system has potential for total coliforms and E. coli inactivation in the pre-treated greywater, reaching 2.1 log units E. coli inactivation in batch experiments for low turbidity samples (21 NTU), and > 2 log units inactivation of total coliforms (and E. coli, when present) for the 24 h HRT-continuous prototype. The continuous flow prototype needs more testing and structural improvements to cope with the difficulties posed by algae growth, as they complicate maintaining conditions of constant flow and make frequent maintenance inevitable.

Doença de Castleman / Castleman's disease

A Doença de Castleman (DC) é rara, sendo também conhecidacomo hiperplasia linfonodal gigante. É mais comumenteencontrada em adultos jovens, com predileção pelo mediastino,embora possa ocorrer em qualquer local do sistema linfático. DC édividida em dois subtipos clínicos, unicêntrico e multicêntrico e doistipos histológicos, hialino-vascular e plasmocítico. Relata-se ocaso de paciente de 19 anos, com uma história clínica de massacervical há sete anos. O diagnóstico definitivo foi feito após aressecção e exame histopatológico, que mostrou lesão tipo hialinovascular.Não houve sinais de recidiva após um ano deseguimento.

Castleman's disease (CD) is a rare disorder, also known as giantlymph node hyperplasia. It's more commonly found in young adults,with predilection to mediastinum, although it may occur in any partof the lymphatic chain. CD is divided into two clinical subtypes,unicentric and multicentric, and two histological types, hyalinevascular and plasma cell. A case of a 19-year-old woman, with ahistory of a cervical mass for 7 years is reported. The definitivediagnosis was made after resection and histopathologicalexamination, which showed hyaline vascular type. There was nosign of recurrence after 1 year.

Labirintite ossificante: relato de um caso e revisão da literatura / Labyrinthitis ossificans: report of one case and literature review

Introdução: Labirintite ossificante é uma patologia caracterizada por surdez neurossensorial, frequentemente secundária a infecção, que gera lesão irreversível na orelha interna. Objetivo: Relatar um caso de labirintite ossificante e realizar uma revisão da literatura. Relato do Caso: É apresentado um caso de indivíduo do sexo masculino, sete anos de idade, com hipoacusia profunda unilateral na audiometria tonal, ausência de reposta na audiometria de tronco encefálico e alterações compatíveis na Tomografia Computadorizada. Conclusão: A labirintite ossificante resulta na ossificação das estruturas da orelha interna. O paciente apresenta um quadro de hipoacusia profunda irreversível, acompanhado ou não de desequilíbrio, que pode ter implicação importante no desenvolvimento sócio-educacional. O diagnóstico tem importante papel na indicação de implante coclear para os casos selecionados.

Introduction: Labyrinthitis ossificans is a pathology characterized by sensorioneural hearing loss; secondary to infectious process, which produces irreversible injury to inner ear. Objective: To report a labyrinthitis ossificans case and review the literature. Case Report: A seven-year-old male patient, with profound hearing loss in tonal audiometry; no response from brainstem audiometry and compatible CT findings. Conclusion: Labyrinthitis ossificans results ossification on the inner ear structures. Pacient presents profound irreversible hearing loss, followed or not by disequilibrium, that can have important implication on educational socio-development. Diagnosis is important for cochlear implantation cases of the selected cases.

Oxygen uptake during walking in patients with rheumatoid arthritis--a controlled study.

OBJECTIVE: To analyze the energy expenditure of patients with rheumatoid arthritis (RA) of functional classes I, II, and III during walking at different speeds on a treadmill. METHODS: Thirty-five consecutive patients selected from the rheumatology outpatient clinic were studied and compared with a control group consisting of 35 healthy individuals paired for age, sex, body weight, and body mass index. An incremental test on a treadmill consistent with normal walking was developed, with metabolic analysis performed at 30 s intervals using a gas analyzer connected to a computerized system. Heart rate, rate of perceived exertion, visual analog scale of pain, Ritchie index, the Scale of the Escola Paulista de Medicina for Evaluation of Articular Movement Range, and the Health Assessment Questionnaire were also used to evaluate functional capacity. RESULTS: Patients with RA showed a greater energy expenditure than controls at the following walking speeds: 3.0 km/h (RA = 229.36 +/- 56.47 kcal/h; controls = 197.44 +/- 52.59), 4.5 km/h (RA = 266.41 +/- 58.94 kcal/h; controls = 231.41 +/- 56.14), and 5.0 km/h (RA = 289.11 +/- 65.35 kcal/h; controls = 250.18 +/- 56.67). Patients with RA presented higher values for all test measures except heart rate. The functional class II group differed significantly from the controls, whereas the functional class I group had values close to normal. CONCLUSION: Patients with RA had a greater energy expenditure during walking compared to healthy controls under the same conditions, and patients with functional class II experienced a greater energy expenditure compared to controls.

The Zymovars of Vibrio cholerae: multilocus enzyme electrophoresis of Vibrio cholerae.

Zymovars analysis also known as multilocus enzyme electrophoresis is applied here to investigate the genetic variation of Vibrio cholerae strains and characterise strains or group of strains of medical and epidemiological interest. Fourteen loci were analyzed in 171 strains of non-O1 non-O139, 32 classical and 61 El Tor from America, Africa, Europe and Asia. The mean genetic diversity was 0.339. It is shown that the same O antigen (both O1 and non-O1) may be present in several genetically diverse (different zymovars) strains. Conversely the same zymovar may contain more than one serogroup. It is confirmed that the South American epidemic strain differs from the 7th pandemic El Tor strain in locus LAP (leucyl leucyl aminopeptidase). Here it is shown that this rare allele is present in 1 V. mimicus and 4 non-O1 V. cholerae. Non toxigenic O1 strains from South India epidemic share zymovar 14A with the epidemic El Tor from the 7th pandemic, while another group have diverse zymovars. The sucrose negative epidemic strains isolated in French Guiana and Brazil have the same zymovar of the current American epidemic V. cholerae.

The zymovars of Vibrio cholerae: multilocus enzyme electrophoresis of Vibrio cholerae

Zymovars analysis also known as multilocus enzyme electrophoresis is applied here to investigate the genetic variation of Vibrio cholerae strains and characterise strains or group of strains of medical and epidemiological interest. Fourteen loci were analyzed in 171 strains of non-O1 non-O139, 32 classical and 61 El Tor from America, Africa, Europe and Asia. The mean genetic diversity was 0.339. It is shown that the same O antigen (both O1 and non-O1) may be present in several geneticaly diverse (different zymovars) strains. Conversely the same zymovar may contain more than one serogroup. It is confirmed that the South American epidemic strain differs from the 7th pandemic El Tor strain in locus LAP (leucyl leucyl aminopeptidase). Here it is shown that this rare allele is present in 1 V. mimicus and 4 non-O1 V. cholerae. Non toxigenic O1 strains from South India epidemic share zymovar 14A with the epidemic El Tor from the 7th pandemic, while another group have diverse zymovars. The sucrose negative epidemic strains isolated in French Guiana and Brazil have the same zymovar of the current American epidemic V. cholerae

Artrite reumatóide: treinamento cardiovascular / Rheumatoid arthritis: Cardiovascular training

Artrite reumatóide (AR), doença inflamatória sistêmica, tem sido estudada quanto aos aspectos de capacidade funcional, gasto energético e condicionamento cardiovascular. Os pacientes com AR apresentam redução da força e resistência muscular, fadiga, depressão e auto-estima diminuída, com a expectativa de vida reduzida em média de 10 a 15 anos. Considerando o grau de comprometimento desses pacientes, nesta revisão discute-se como um programa de treinamento cardiovascular pode contribuir para a melhora no consumo de oxigênio e índices cardíacos e, assim, de sua qualidade de vida

Amelogênese imperfeita hereditária, uma disgenesia de estrutura: revisão bibliográfica analítica e apresentação de casos clínicos / Hereditary amelogenesis imperfecta, an anomaly of shape: analytical review of the literature and presentation of clinical cases

A amelogênese imperfeita hereditária é uma alteração de caráter genético que afeta o esmalte dentário de ambas as dentições. É uma disgenesia de estrutura geneticamente heterogênea, podendo ser autossômica dominante, autossômica recessiva ou ligada ao cromossomo X. Pode ser de dois tipos: hipoplásica, com o esmalte apresentando pouca espessura e associado a falhas na superfície e hipocalcificada ou hipomineralizada, apresentando um esmalte insuficientemente mineralizado e com consistência mais mole que o normal. No que concerne ao tratamento dessa disgenesia, são relevantes as questões da estética, da psicologia e das restaurações. Este trabalho objetivou como propósitos, rever analítica e criticamente a literatura pertinente e apresentar casos clínicos atendidos na Clínica Integrada Infantil do Curso de Odontologia da Universidade Estadual de Maringá

Influência de vasoconstritores associados a anestésicos locais sobre a pressäo arterial de ratos hipertensos e normotensos / Influence of vasoconstrictors associated with local anesthetics on the arterial pressure of hypertensive and normotensive rats

A utilizaçäo de anestésicos locais associados a vasoconstritores em pacientes hipertensos é controversa. neste estudo, verificamos a influência desta associaçäo sobre a pressäo arterial caudal (PA) em ratos hipertensos DOCA-sal. Após ligeira anestesia com éter, os anestésicos GRUPO I - lidocaína 2 por cento sem vasoconstritor, GRUPO II - lidocaína com fenilefrina, GRUPO III - lidocaína a 2 por cento com noradrenalina, GRUPO IV - prilocaína 3 por cento com felipressina, GRUPO V - mepivacaína 2 por cento com adrenalina e GRUPOVI - mepivacaína com noradrenalina foram injetados na submucosa da boca (anestesia infiltrativa), em ratos DOCA-sal e controles. A PA foi determinada 5 e 15 minutos após a primeira dose do anestésico e também 5 e 15 minutos após a segunda dose. Os dados obtidos indicaram que: a) a PA dos ratos DOCA-sal (193,05 ñ 4,25 mmHg; n = 43) foi significativamente superior àquela observada nos animais controles 115,64 ñ 2,47 mmHg; n = 43) e, b) näo houve variaçäo significativa nas PA observadas em animais DOCA-sal e controles pela administraçäo dos anestésicos locais testados. Assim, nossos dados experimentais sugerem que a presença de agentes vasoconstritores associados à lidocaína 2 por cento, à prilocaína 3 por cento e à mepicacaína 2 por cento näo interferem na PA desses animais, neste modelo experimental de hipertensao.

Evolutionary control of infectious disease: prospects for vectorborne and waterborne pathogens

Evolutionary theory may contribute to practical solutions for control of disease by identifying interventions that may cause pathogens to evolve to reduce virulence. Theory predicts, for example, that pathogens transmitted by water or arthropod vectors should evolve to relatively high levels of virulence because such pathogens can gain the evolutionary benefits of relatively high levels of host exploitation while paying little price from host illness. The entrance of Vibrio cholerae into South America in 1991 has generated a natural experiment that allows testing of this idea by determining whether geographic and temporal variations in toxigenicity correspond to variation in the potencial for waterborne transmission. Preliminary studies show such correspondences: toxigenicity is negatively associated with access to uncontaminated water in Brazil; and in Chile, where the potential for waterborne transmission is particularly low, toxigenicity of strains declined between 1991 and 1998. In theory vector-proofing of houses should be similarly associated with benignity of vectorborne pathogens, such as the agents of dengue, malaria, and Chagas'disease. These preliminary studies draw attention to the need for definitive prospective experiments to determine whether interventions such as provisioning of uncontaminated water and vector -proofing of houses cause evolutionary reductions in virulence.

The Amazonia variant of Vibrio cholerae: molecular identification and study of virulence genes

The pathogenic O1 Amazonia variant of Vibrio cholerae has been shown previously to have a cytotoxin acting on cultured Vero and Y-1 cells, and to lack important virulence factors such as the cholera toxin (Coelho et al. 1995a). This study extends the molecular analysis of the Amazonia strains, detecting the presence to the toxR gene, with a very similar sequence to that of the El Tor and classical biotypes. The outer membrane proteins are analysed, detecting a variation among the group of Amazonia strains, with three different patterns found. As a by-product of this work a polymerase chain reation fragment was sequenced, reading part of the sequence of the Lon protease of the Amazonia strains. The gene was not previously described in V. cholerae, but its sequences is present in the TIGR database specific for this species.

Avaliaçäo do potencial carcinogênico do formocresol diluído a 1/5 e do glutaraldeído a 2 por cento no modelo experimental DMBA-induzido / The evaluation of the carcinogenic potential of 1/5 formocresol and 2 per cent glutaraldehyde in DMBA-induced model

O objetivo deste trabalho foi avaliar o potencial carcinogênico do formocresol e do glutaraldeído, nas concentraçöes utilizadas clinicamente, em testes de longa duraçäo, a partir do modelo experimental em hamsters sírius dourados para estudo da carcinogênese química bucal induzida pelo uso do DMBA a 0,5 por cento. A análise comparativa macro e microscópica das alteraçöes provocadas pela aplicaçäo tópica do formocresol diluído a 1/5 e glutaraldeído a 2 por cento sobre a mucosa lingual lateral, precedida ou näo por escarificaçäo, após 7, 13 e 20 semanas, permitiu verificar que o formocresol diluído a 1/5 e o glutaraldeído a 2 por cento induzem alteraçöes morfológicas que caracterizam displasia epitelial; näo houve induçäo à formaçäo de papilomas e carcinomas nos animais, tal como ocorreu com o DMBA a 0,5 por cento