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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

The Effect of Prenatal Stress on a Mouse Model of Allergic Airway Disease

Chau, Jessie T. 04 1900 (has links)
<p>Prenatal life events have been long observed to be able to influence disease into adulthood in both epidemiological and animal studies. Prenatal stress (maternal stress during gestation) is one of such factors that has been shown to impact cognition and behaviour of the offspring. However, the effects of prenatal stress on the immune system are not understood. This study has evaluated the effects of prenatal stress on a murine model. Prenatal stress increased allergic airway inflammation in male, but not female offspring following sensitization and challenge with cockroach extract. This corresponded with stress-induced changes in the immune environment of non-sensitized animals. These changes included a decrease in regulatory T cells at baseline in males compared to non-stressed controls and increased splenic dendritic cell percentage and cytokine, particularly IFN-γ, secretion compared to prenatally stressed females. In females, prenatal stress decreased allergic inflammation, which corresponded to a decreased percentage of dendritic cells in the lung and mesenteric lymph node. Prenatal stress did not affect dendritic cell antigen presentation in ether male or female offspring. There was no evidence to suggest a prenatal stress induced change in glucocorticoid sensitivity of dendritic cells. In order to explore the possibility of prenatal stress induced decrease of parasympathetic output, a vagotomy model was used as a proof of concept in naïve animals not exposed to prenatal stress. Vagal modulation of dendritic cell phenotype and function was assessed. While there was some evidence that vagotomy may indirectly modulate dendritic cell function, its effects on the immune system were different then the changes caused by prenatal stress and thus it is a role of reduced parasympathetic output was not supported. Overall this data indicates a role of prenatal stress on the immune system with clear sex differences, but the mechanism for how this occurs is currently unknown. Further research is needed to investigate the role of TLRs and IFN-γ in this model, as well as other possible mediators of prenatal stress such as the changes to the parasympathetic nervous system that may in turn mediate alterations to the immune system. Differences in when the effects of prenatal stress are expressed during postnatal life are discussed.</p> / Master of Science (MSc)
132

Development of immunotherapy using antigen-loaded multifunctional small extracellular vesicles / 抗原搭載多機能性細胞外小胞を利用した免疫療法の開発に関する研究

Liu, Wen 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第23837号 / 薬科博第152号 / 新制||薬科||17(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 髙倉 喜信, 教授 山下 富義, 教授 小野 正博 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM
133

Interleukin-33 modulates the expression of human β-defensin 2 in human primary keratinocytes and may influence the susceptibility to bacterial superinfection in acute atopic dermatitis.

Alase, Adewonuola A., Seltmann, J., Werfel, T., Wittmann, Miriam 12 1900 (has links)
No / Background  Interleukin (IL)-33 is a member of the IL-1 family and has been implicated in Th2-driven allergic diseases such as atopic dermatitis (AD) and asthma. The principal Th2 cytokine IL-4, found highly expressed in acute allergic eczema, is known to downregulate human β-defensin 2 (hBD2) expression in human keratinocytes and this is associated with superinfection in patients with AD. Objectives  To investigate the effect of IL-33 on the expression of hBD2 in human keratinocytes. Methods  hBD2 production by stimulated keratinocytes was measured by enzyme-linked immunosorbent assay. Results  Our results showed that serum is a very potent inducer of hBD2 and 2·5% human serum was much more potent in inducing hBD2 than 20 ng mL−1 of tumour necrosis factor-α. Interestingly, serum from patients with AD showed an impaired ability to induce hBD2 in normal keratinocytes. IL-33 significantly downregulated serum-induced hBD2. The downregulatory capacity of IL-33 was found to be 1·5- to 2-fold weaker compared with IL-4. Conclusions  Our data suggest that IL-33 can significantly contribute to the decreased expression of hBD2 in acute eczematous reaction clinically characterized by spongiosis and oozing – thus indicative for contact of the epidermis with serum components.
134

Which population level environmental factors are associated with asthma, rhinoconjunctivitis and eczema? Review of the ecological analyses of ISAAC Phase One.

Asher, M Innes, Stewart, Alistair W, Mallol, Javier, Montefort, Stephen, Lai, Christopher K W, Aït-Khaled, Nadia, Odhiambo, Joseph, Chiarella, Pascual, The ISAAC Phase One Study Group 21 January 2010 (has links)
Revisión por pares
135

Dermal cell trafficking : from microscopy to microdialysis /

Sjögren, Florence, January 2005 (has links) (PDF)
Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 6 uppsatser.
136

Sensibilisation allergénique au cours des huit premières années de vie, facteurs et morbidité associés dans la cohorte de naissances PARIS / Allergic sensitization over the first eight years of life, associated factors and morbidity in PARIS birth cohort

Gabet, Stephan 02 October 2017 (has links)
Contexte. Les premières années de vie apparaissent particulièrement propices au développement de la sensibilisation allergénique. Objectifs. Cette thèse vise à : i) décrire les profils de sensibilisation allergénique chez le nourrisson et l’enfant, ii) étudier l’association entre ces profils et la morbidité allergique et iii) identifier les facteurs de risque de cette sensibilisation. Méthodes. Dans le cadre du suivi de la cohorte prospective de naissances en population générale Pollution and Asthma Risk: an Infant Study (PARIS), la sensibilisation allergénique a été évaluée chez 1 860 nourrissons à 18 mois et 1 007 enfants à 8/9 ans par dosage des IgE spécifiques dirigées contre 16 et 19 allergènes, respectivement. Les informations concernant la santé et le cadre de vie des enfants ont été recueillies par questionnaires standardisés répétés. Des profils de sensibilisation et des profils de morbidité ont été identifiés par classification non supervisée et mis en relation par régression logistique multinomiale. Enfin, les facteurs associés à la sensibilisation allergénique chez le nourrisson ont été étudiés par régression logistique multivariée. Résultats. Dès 18 mois, 13,8% des enfants étaient sensibilisés et 6,2%, multi-sensibilisés. À 8/9 ans, ces prévalences étaient de 34,5% et 19,8%, respectivement. Les profils de sensibilisation identifiés chez le nourrisson (3) et dans l’enfance (5) différaient au regard de la morbidité allergique. L’analyse étiologique a permis de préciser le rôle des expositions précoces aux allergènes et aux microorganismes sur la sensibilisation allergénique. Conclusion. Cette thèse contribue à une meilleure compréhension de l’histoire naturelle de la sensibilisation allergénique, et ce, dès les premières années de vie. Cette connaissance est essentielle à la prévention des maladies allergiques qui en découlent. / Background. The first years of life appear to be critical for the development of allergic sensitization. Objectives. This thesis aims: i) to describe allergic sensitization profiles in infants and children, ii) to assess the link between these sensitization profiles and allergic morbidity, and iii) to identify risk factors for allergic sensitization. Methods. This work concerns children involved in the Pollution and Asthma Risk: an Infant Study (PARIS) population-based prospective birth cohort. Allergic sensitization was assessed in 1,860 18-month-old infants and 1,007 8/9-year-old children by specific IgE measurements towards 16 and 19 allergens, respectively. Lifelong health and living condition data were collected by repeated standardized questionnaires. Sensitization profiles and morbidity profiles were identified using unsupervised classification, and related to each other by multinomial logistic regression. Finally, risk factors for early allergic sensitization were assessed by multivariate logistic regression. Results. As soon as 18 months of age, 13.8% of children were sensitized and 6.2%, multi-sensitized. When 8/9 years old, corresponding prevalence was 34.5% and 19.8%, respectively. Sensitization profiles identified in infancy (3) and in childhood (5) differed in terms of allergic morbidity. Risk factor analysis allowed to clarify the role of early exposure to allergens and microorganisms on allergic sensitization. Conclusion. This thesis improves the natural history of allergic sensitization understanding, as soon as the first years of life. This knowledge is essential for subsequent disease preventing.
137

Phenotyping of chronic respiratory diseases in the South of Vietnam

Chu Thi, Ha 25 June 2019 (has links) (PDF)
Chronic respiratory diseases (CRDs) include chronic diseases involving the airways and other structures of the lung. In the current circumstance of Vietnam, people are exposed to numerous risk factors of CRD, such as heavy smoking, high frequency of pulmonary tuberculosis, chronic helminthiasis, allergic factors, migration and urbanization (the last associated with traffic-related pollution). The phenotype diagnoses should take into account the risk factors of each individual besides the clinical features, while the differential diagnoses mostly depend on the available techniques in each healthcare center. Our aim was to improve the differential diagnoses of the 3 most frequent CRDs: chronic obstructive pulmonary disease (COPD), asthma and COPD – asthma overlap syndrome (ACOS), in Vietnam. In the first part, we evaluated the prevalence of the allergen sensitization among patients with CRD, in regard to the urban and rural area in the South of Vietnam. House dust mites and cockroach droppings were the most frequent sensitizer. Compared with participants born in the urban setting, those born in the rural environment were less frequently sensitized and this protective effect disappeared in the case of migration from rural to urban areas. In the second part, we evaluated skin prick test as a method to screen dust mite sensitization in CRD in southern Vietnam. The data suggested that, in the present circumstance, skin prick test can be used to screen mite sensitization. In the third part, we evaluated the risk of mite sensitization in the native and migrant population, in regard to several environmental factors. Consistently with the hygiene hypothesis, compared to urban, exposure to high endotoxin concentration in rural was a protective factor against allergic sensitization. We reported for the first time that this effect was reversible among the migrants from rural to urban setting in association with lower endotoxin exposure. In the fourth part, we have defined asthma, COPD and ACOS based on clinical symptoms, cumulative smoking and airway expiratory flow with reversibility, on one side, and the age-related of the different phenotypes, on the other side. We hypothesized that the cumulative exposure to noxious particles should increase the age-related prevalence of COPD, while due to the immunosenescence process, the prevalence of IgE-mediated asthma should decrease with age, and ACOS prevalence being not related to age due to the combined mechanisms.  In conclusion, we showed in the South of Vietnam that:1) mites and cockroach allergens were the most frequent sensitizer in chronic respiratory diseases;2) the skin prick test to mite has been validated to screen mite sensitization;3) associated with a reduced level of endotoxin level, migration from rural to the urban setting was a risk factor of mite sensitization in chronic respiratory diseases;4) based on the clinical symptoms, spirometric values, and cumulative smoking, the diagnosis of asthma, COPD and ACOS have been made and their prevalence were 25, 42 and 33%, respectively. / Doctorat en Sciences biomédicales et pharmaceutiques (Médecine) / info:eu-repo/semantics/nonPublished
138

Aspectos neuroimunológicos do ecstasy (N-metil-3,4-Metilenodioximetanfetamina-MDMA), na inflamação alérgica pulmonar em camundongos Balb/C. / Neuroimmunological aspects of ecstasy (N-methyl-3,4-Methylenedioxymethamphetamine-MDMA) on lung inflammatory response in Balb/C mice.

Stankevicius, Daniel 01 July 2010 (has links)
O N-metil- 3-4, metilenodioximetanfetamina (MDMA) ou ecstasy tem sido freqüentemente usado por jovens. Analisamos neste trabalho, dentro de uma perspectiva neuroimune, os efeitos da administração aguda de MDMA em parâmetros comportamentais, neuroendócrinos, hematatológicos e imunes de camundongos Balb/C, usando para esta última finalidade um modelo de asma experimental. O MDMA produziu: 1- aumento diferencial da atividade locomotora nas diferentes zonas do campo aberto; aumento na locomoção total e diminuição da atividade exploratória no hole-board; aumento da porcentagem de entradas e da taxa de permanência nos braços abertos do LCE; aumento no tempo gasto na caixa de saída e diminuição do número de acessos de risco em uma caixa de exposição a um predador; 2- aumento dos níveis séricos de corticoterona; 3- aumento dos níveis de noradrenalina no estriado e córtex frontal, aumento nos níveis de dopamina e de DOPAC no estriado, diminuição dos níveis de DOPAC corticais, aumento de 5-HT e 5-HIAA no estriado, diminuição dos níveis de 5- HIAA e do turnover de serotonina no hipotálamo e diminuição do \"turnover\" de dopamina no estriado e córtex frontal; 4- alteração na migração de leucócitos em camundongos alérgicos com diminuição da porcentagem de linfócitos e monócitos circulantes, diminuição do número de granulócitos no lavado bronco alveolar (LBA), efeitos estes que foram revertidos pelo pré-tratamento com RU-486; 5 redução da expressão de L-selectinas por monócitos e tendência de redução da expressão de L -selectinas por neutrófilos no pulmão; 6- diminuição das produções espontâneas de IL-4, IL-5 e IL-10 e de IL-4 em cultura estimulada com LPS; 7- redução da contração da traquéia isolada de animais alérgicos e 8- redução da desgranulação dos mastócitos em brônquios intrapulmonares. Sugeriu-se que o estresse/ansiedade induzidos pelo MDMA tenham ativado o eixo HHA e/ou do sistema nervoso autonômico simpático dos camundongos, alterando a resposta imune dos mesmos na vigência de um modelo de asma. A inflamação alérgica pulmonar desponta, assim, como importante ferramenta para o entendimento da ação de drogas de abuso em processos neuroimunológicos. / The N-metil- 3-4, metilenodioximetanfetamina (MDMA) or ecstasy is a drug widely used amongst young people. This study was undertaken to analyze, under a neuroimmune perspective, the effects of acute MDMA administration on behavioral, neuroendocrine, hematological and immune parameters on Balb/C mice, using for the latter purpose the allergic lung inflammatory response model. It was observed that MDMA produced in mice: 1- a differential increase on total locomotion in the different open-field zones; an increase on total locomotion and a decrease on exploratory activity in the hole-board; an increase on both percentage of entrances and time spent on plus-maze open arms; an increase on time spent in the starting box and a decrease of risk assessments in a predator exposition box; 2- an increase in corticosterone serum levels; 3- an increase in striatal and frontal cortex noradrenaline levels, an increase in striatal dopamine and DOPAC levels, a decrease in cortical DOPAC levels, an increase in striatal 5-HT and 5-HIAA levels, a decrease in both 5-HIAA levels and 5-HT turnover rates in hypothalamus and a decrease in striatal and cortical dopamine \"turnover\" rates; 4- an alteration on leukocyte migration in allergic mice, i.e., decreased percentage of peripheral blood lymphocytes and monocytes, decreased number of granulocytes on bronchoalveolar lavage fluid ( LBA); these effects were reverted by previous RU-486 treatment; 5- a decrease in L-selectin expression by monocytes and a tendency towards a decrease in L-selectin expression by lung neutrophils; 6- a decrease on expontaneous production of IL-4, IL-5 e IL-10 and IL-4 in LPS-stimulated cultures; 7- a decrease in the contraction of allergic mice isolated trachea; and, 8- a decrease in bronchial mastocytes degranulation. It was suggested that MDMA-induced anxiety/stress symptoms increasing HHA-axis and/or the autonomic nervous system activities this leading to the immune changes observed presently in the allergic lung inflammation model of asthma used. This model, thus, emerges as a useful tool for the understanding of neuroimmune effects of drugs of abuse.
139

Perfil celular, funcional e bioquímico das vias aéreas de trabalhadores da limpeza profissional frente à exposição no local de trabalho / Cellular, functional and biochemichal profile of airways of workers are exposed to occupational agents

Lima, Cynthia Mafra Fonseca de 08 December 2015 (has links)
INTRODUÇÃO: Há evidências consistentes a partir de estudos epidemiológicos de que os profissionais de limpeza têm um risco elevado de desenvolver asma. Os determinantes deste risco não são totalmente conhecidos. Esses trabalhadores estão expostos a agentes ocupacionais de baixo e alto peso molecular, tanto a agentes sensibilizantes, como a irritantes. É importante produzir evidências de que este risco está relacionado ao trabalho e não às condições sociais ou outros fatores concorrentes, conhecer a anormalidade patológica subjacente, e investigar os possíveis agentes. O acúmulo deste conhecimento permitirá a proposição de medidas para substituição ou controle do uso dos agentes envolvidos e prevenção da ocorrência de novos casos desnecessariamente. Além disso, o uso de novas técnicas não invasivas, como a citologia do escarro e A FeNO, poderá facilitar o diagnóstico precoce dos casos. Desta maneira, este estudo pretende avaliar se o ambiente de trabalho induz inflamação pulmonar em trabalhadores assintomáticos, antes da alteração das provas funcionais e a eficácia do escarro induzido e da FeNO NO como marcadores de inflamação pulmonar precoce entre trabalhadores de limpeza profissional não doméstica. MÉTODO: Os trabalhadores foram avaliados através da comparação da citologia do escarro, valores da FeNO, espirometria e PFE, realizados durante o período de trabalho e após as férias. A amostra foi caracterizada através do questionário de triagem do estudo de saúde respiratória da Comunidade Européia, questionário de sintomas respiratórios e a pontuação no ISAAC. RESULTADOS: Em nosso estudo, encontramos um aumento significativo dos valores do VEF1 após o período de férias, (pré 2,76 ± 0,57 e pós 2,94 ± 0,61; p < 0,05) apesar de estar dentro da normalidade, em ambos os períodos. A média das medidas do PFE também mostrou-se maior durante o período de férias em comparação ao período de trabalho, embora não estatisticamente significante (pré 366,6 ± 54,1 e pós 386,4 ± 62,9 e p > 0,05). Encontramos uma redução dos valores da medida da FeNO após as férias (pré 16,3 ± 9,7 e pós 13,8 ± 7,8 p < 0,05) e redução de eosinófilos (pré 0,019 ± 0,05 e pós 0,003 ± 0,01 p < 0,05), linfócitos (pré 0,16 ± 0,35 e pós 0,01 ± 0,09 p < 0,05) e macrófagos (pré 0,421 ± 0,47 e pós 0,235 ± 0,30 p < 0,05) na citologia do escarro induzido, realizada após o período de férias. CONCLUSÃO: Demonstramos que o ambiente ocupacional ao qual são expostos os trabalhadores de limpeza profissional não doméstica provoca inflamação nas vias aéreas de trabalhadores assintomáticos. Esta inflamação pode ser aferida por métodos não invasivos como escarro induzido e FeNo, antes do aparecimento de alterações nas provas funcionais, embora estes métodos ainda necessitem de padronização. São necessários novos estudos para quantificar a exposição ao cloro e sua relação com inflamação, assim como para padronizar o uso do escarro induzido e da FeNO no diagnóstico de doenças ocupacionais entre trabalhadores de limpeza, além de medidas preventivas e educativas nesta população / There is consistent evidence from epidemiological studies that the cleaning professionals have a high risk of developing asthma. The determinants of this risk are not fully known. These workers are exposed to occupational agents of low and high molecular weight, both the sensitizing agents, such as irritant. It is important to produce evidence that this risk is related to work and not social conditions or other competitive factors, know the underlying pathological abnormality, and investigate possible agents. The accumulation of this knowledge will allow proposing measures to replace or control the use of the agents involved and preventing the occurrence of new cases unnecessarily. In addition, the use of new non-invasive techniques, such as sputum cytology and the FeNO may facilitate early diagnosis of cases. Thus, this study aims to assess if the work environment induces lung inflammation in asymptomatic workers, before the change of functional tests and the effectiveness of induced sputum and exhaled NO as early lung inflammation markers between professional cleaning workers. METHOD: Workers were evaluated by comparing the sputum cytology, FeNO values, spirometry and PEF, made during the work period and after the holidays. The sample was characterized by screening questionnaire of respiratory health study of the European Community, questionnaire of respiratory symptoms and a score in ISAAC. RESULTS: In our study, we found a significant increase in FEV1 values after the vacational period, (pre 2.76 ± 0.57 and 2.94 ± 0.61; post; p < 0.05) despite of being within the normal range in both periods. The average peak flow measurements also was higher during the vacational period compared to the period of work, although not statistically significant (366.6 ± 54.1 pre and post 386.4 ± 62.9; p > 0.05). We found a reduction of the exhaled measured values of NO after the holidays (pre and post 16.3 ± 9.7, 13.8 ± 7.8; p < 0.05), reduction of eosinophils (pre and post 0.05 ± 0.019, 0.003 ± 0.01; p < 0.05), lymphocytes (pre and post 0.16 ± 0.35, 0.01 ± 0.09; p < 0.05) and macrophages (pre and post 0.421 ± 0.47 0.235 ± 0 30 p < 0.05) in induced sputum cytology, performed after the holiday period. CONCLUSION: We demonstrate that the occupational environment to which professional cleaning non-domestic workers are exposed causes inflammation in the airways of asymptomatic workers. This inflammation can be measured by non-invasive methods such as induced sputum and FeNo, before the onset of changes in functional tests, although these methods still require standardization. Further studies are needed to quantify the exposure to chlorine and its relation to inflammation, as well as to standardize the use of induced sputum and exhaled nitric oxide in the diagnosis of occupational diseases among cleaning workers, and preventive and educational measures in this population
140

Etiologia e epidemiologia da dermatite alérgica sazonal em ovinos no sul do Rio Grande do Sul / Etiology and epidemiology of seasonal allergic dermatitis in sheep in southern of Rio Grande do Sul

Corrêa, Tiago Gallina 14 October 2005 (has links)
Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-13T19:34:20Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-13T19:42:38Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) / Made available in DSpace on 2017-04-13T19:42:38Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) Previous issue date: 2005-10-14 / Sem bolsa / Dermatite alérgica estacional foi estudada em um rebanho de ovinos Hampshire Down em um estabelecimento no município de Capão do Leão, Rio Grande do Sul. A epidemiologia, sinais clínicos e lesões macroscópicas foram observadas no estabelecimento verificando-se a época de ocorrência da enfermidade, a idade e sexo dos animais afetados e localização das lesões. A patologia microscópica foi estudada em biopsias de pele de ovinos afetados. Para a verificação da etiologia, insetos foram capturados com aspiradores entomológicos, semanalmente, das 16h00minh às 09h00minh, entre os meses de janeiro a abril de 2005. Os dados relativos à temperatura média, umidade relativa do ar e velocidade média dos ventos na região de ocorrência da doença foram obtidos na Estação Agro-climatológica da Universidade Federal de Pelotas. A prevalência da doença no período estudado foi de 40% e animais de qualquer idade e ambos os sexos foram afetados. A enfermidade ocorreu principalmente entre dezembro e março e alguns animais permaneceram com lesões durante todo o ano. Os sinais clínicos eram de inquietação e prurido e as lesões ocorriam principalmente nas orelhas, ao redor dos olhos e na região ventral do abdômen, caracterizando-se pela presença de eritema e pápulas, nos casos agudos, e espessamento da pele com rachaduras, exsudação, formação de crostas, e alopecia, nos casos crônicos; esses freqüentemente apresentavam infecções secundárias. As lesões histológicas eram principalmente de dermatite eosinofílica perivascular, observando-se, também, hiperqueratose, acantose e presença de pústulas sub corneais ou intra-epidérmicas nos casos crônicos. Os insetos capturados no período de estudo da doença foram identificados como Anopheles albitarsis e Culicoides insignis. Durante a captura observou-se que os animais apresentavam prurido intenso quando picados por Culicoides, mas não por Anopheles. As temperaturas média mínima e máxima no período, foram de 17ºC e 28ºC, respectivamente, e a velocidade média dos ventos foi de 12,84km/h. Ambas as espécies de insetos capturados têm hábitos noturnos aproximando-se dos animais para hematofagia em torno de 30min após o ocaso do sol.Testes intradérmicos realizados com antígenos obtidos a partir desses dípteros revelaram reação de hipersensibilidade aos antígenos de C. insignis. Os resultados obtidos indicam que a enfermidade estudada ocorre em conseqüência de hipersensibilidade imediata causada pela picada desse díptero. / A seasonal dermatitis was studied in a Hampshire Down flock in a farm at the minicipality of Capão do Leão, state of Rio Grande do Sul, southern Brazil. Frequency and seasonal distribution of the disease, breed, sex and age of affected sheep, and clinical signs, macroscopic pathology and distribution of the lesions were obtained by visiting the farm. Histological lesions were studied in skin biopsies of affected sheep. Biting insects were collected weekly between 4:00 p.m. to 9:00 a.m., from January to April of 2005 to identify the etiological agent of disease. Data about temperature, humidity and wind speed in the region where the disease occurs were obtained in the agro climatologic Station of Pelotas Federal University. The prevalence of disease during the study period was 40% and the age of affected animals was variable. The disease occurs between December and March, but some animals stayed with lesions during the whole year. Clinical signs were characterized by pruritus and skin lesions in the ears, around the eyes, and ventral abdomen. Erythema and papules were observed in acute cases. In chronic cases, the skin was thicken, exsudative, crusty and alopecic, frequently with secondary infections. Histological lesions of affected sheep were characterized by perivascular eosinofilic dermatitis. Hyperkeratosis, acanthosis and intraepidermal pustules were observed in chronic lesions. Anopheles albitarsis and Culicoides insignis were captured during the observation period. Sheep showed pruritus mainly during de Culicoides bites. The mean minimum and maximum temperature in the period were 17ºC e 28ºC, respectively, and the mean speed wind was 12,84km/h. Both insects were caught when they approached the sheep bait 30minutes after sunset. Intradermal tests performed with de antigens of the insect extracts showed hypersensitivity reaction to C.insignis antigens. Based on the results it was suggested that the disease occurs as a consequence of an immediate hypersensitivity caused by C. insignis bite.

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