Avaliação dos efeitos da dexametasona em órgãos do sistema imune - timo e bursa de fabricius- e em jejuno de frangos.

A integridade do sistema imune e do trato gastrointestinal está diretamente relacionada à sanidade das aves e ao desempenho zootécnico. Com intenção de melhor compreender estes sistemas e sua interação, o presente estudo foi desenvolvido. O objetivo do trabalho foi avaliar os efeitos da dexametasona nos órgãos linfoides - timo e bursa de Fabricius (BF) - e nas estruturas do jejuno, relacionando-os entre si e ao peso final dos animais. Para tal, foram utilizadas 33 amostras de BF, timo e intestinos, os quais foram processados histologicamente e corados com H&E. As lâminas de BF e de timo foram avaliadas por pelo menos dois histopatologistas, sendo utilizada a moda para determinar o escore de depleção de cada amostra. Foram obtidas fotomicrografias digitais de dez vilosidades por jejuno, nas quais mensuraram-se o comprimento e a largura de vilo e a profundidade de uma cripta associada, a altura de núcleo de enterócito, o comprimento de núcleo e a altura de microvilosidade. As medições foram realizadas no Software Motic 2.0®. Após, foram aplicados testes estatísticos paramétricos, utilizando o Software SPSS e o Software JMP-SAS. Observou-se a média de 4,20g nas BF de aves controles, ao passo que em animais submetidos à dexametasona a média 0,74g (p0,05). Intestinos de aves controles apresentaram comprimento em média 1366,4μm maiores e largura de vilosidades em média 58,4μm maiores que aves submetidas a tratamento (p0,05). Control poultry intestines showed, in average, 1366,4μm larger length, and 58,4μm higher mean width villi than poultry submitted to treatment (p<0,05). Treated poultry obtained 15,3% of weight gain in one week after finished the treatment, while control poultry presented 26,7% of weight gain in the same period. Between thymus weight and BF weight we obtained 93,1% correlation and regression coefficient (r2) of 86,7%. Likewise, between thymus weight and poultry weight the r2 was 86,4%. Among BF weight and poultry weight, we observed r2 of 71,8%. On the other hand, the parameters evaluated in the intestines showed no significant correlation. Length of villi and thymus weight presented correlation close to 50% and r2 of 22.5%. In this study, it was possible to evaluate the immunosuppressive effects of dexamethasone in thymus, BF and jejunum structures. There was reduction in weight gain in poultry treated with dexamethasone. It was possible to correlate lymphoid depletion and final weight of poultry. Correlation between villi length and thymus weight was also demonstrated

Determining the best sectioning method and intestinal segment for morphometric analysis in broilers

Brazilian poultry production is very efficient and demands maximum broiler performance. Therefore, digestive system pathologies have a relevant role. Considering it is difficult to obtain consistent information on intestinal morphometric analysis, this study aimed at establishing essential and clear criteria for the collection of intestinal segments for morphometric analysis. Fifteen 13-d-old broilers were sacrificed and three intestinal segments were collected per bird. Two 3-cm long sections were obtained from each of the intestinal segments. Samples were collected open or closed. The closed samples were transversely, hemicylindrically, or longitudinally sectioned. Samples were processed and stained with hematoxylin and eosin. The number of microscopic fields in each section was counted. Villi presenting the base clearly embedded in the submucosa, no damage or folds, and simple columnar epithelium at the tip were considered adequate for measurements. These villi were counted in each sample. The results shows that hemicylindrical sections presented the highest number of observation fields, with an average of 9.76 fields. Jejunum samples were among the three highest average villi counts, with 18.23 in longitudinal sections and 15.61 in hemicylindrical sections. The results of the present study indicate that hemicylindrical sectioning and jejunal samples were, respectively, the best sectioning method and the best intestinal segment for the morphometric analysis of the intestines of broilers

Characterization of Immune and Enteric Systems of Broilers after Imunosupression with Dexamethasone

Background: Bursa of Fabricius (BF) and the thymus are primary lymphoid organs of poultry and play a major role in avian immunity. Enteric system is also involved in immunity. Several pathologic conditions directly impact BF and thymus size, and also affect intestinal parameters. Besides, there are several immune system depressor agents which affect birds. The selection of glucocorticoid as inducer of immunosuppression is applied in many experiments; however there are few studies that are applied to the reality in the field. In this context, the aim of this study was to evaluate the effects of dexamethasone as an inducer of immunosuppression on lymphoid organs and microscopic structures of the jejunum.Materials, Methods & Results: One-day-old chicks were used as a control group (n = 8) and the treated group (n = 25) received intramuscular dexamethasone on 21, 23, 24 and 26 day-old. Control birds and treated birds were euthanized 8, 16, 24, 32 and 40 h after inoculation; four control birds and six treated birds were euthanized on the eighth day after the last inoculation. Thymus, BF and jejunum were collected during the necropsy. The selected organs were processed, stained with hematoxylin and eosin and photographed. The BF and thymus cuts were evaluated by three histopathologists to determine the depletion score. Ten villi of each jejunum were evaluated for width and length of villi, depth crypt, microvillus length, enterocyte length of each villus, and wall thickness. Treated birds presented a mean weight lower than control group during all the experiment. The mean weight and the relative weight of the BF and thymus of control birds were significantly higher than treated ones. The lymphocyte depletion in BF and thymus scores differed significantly between groups, being higher in the group challenged with dexamethasone. There were no significant differences between groups for depth of crypt, height of core and height of microvilli. The intestines of the control group had higher mean values for length of villi, width of villi, height of enterocyte and thickness of wall. Significant correlation between weight of thymus and weight of BF, between weight of thymus and weight of bird and between weight of BF and bird weight were found.Discussion: Easy administration, low cost and the absence of suffering during inoculation make the use of glucocorticoids more advantageous to mimic immunosupression in poultry. Treatment with dexamethasone interfered directly in the weight of the birds. Evaluation of immune response of birds can be performed by the ratio of the BF weight in relation to the weight of the bird, as observed in the present study. The relative weight of the BF of untreated animals varied at all ages between 0.21% and 0.29%. It was also observed that the relative weight of BF and thymus in immunosuppressed birds tended to increase according to the end of the treatment. Depletion scores were higher in thymus, suggesting that glucocorticoid promoted more harmful effects on this organ. Dexamethasone had negative influence on length of villus, once mean value was 13% lower than those of control group. Width of villus and height of enterocyte core of treatment group were lower than those observed in control animals. Coefficient of determination greater than 70% was observed for almost all established relationships, except for the length of villi and weight of the thymus. Administration of dexamethasone promotes significant and negative effects on the gain of weight, length of villi, width of villi and height of enterocytes. These finding are useful for future experiments with controlled immunosuppression induction, once it provides significant information of the secondary effects of glucocorticoids administration in poultry

A técnica de reação em cadeia da polimerase (PCR) para a detecção de genes de virulência em Campylobacter jejuni e sua aplicação na rotina veterinária.

A campilobacteriose é uma zoonose de distribuição mundial, que causa gastroenterite em humanos. As ocorrências de surtos alimentares causados por bactérias do gênero Campylobacter têm sido relacionadas ao consumo de produtos de origem animal, principalmente aos produtos de procedência avícola. As bactérias expressam genes que codificam fatores de virulência que propiciam a colonização e a ocorrência de eventos que subvertem a fisiologia do hospedeiro. Os genes cdtA, cdtB e cdtC codificam a proteína CDT (Cytolethal distending toxin), considerada um dos principais fatores de virulência de Campylobacter jejuni, que contribui para o desenvolvimento de diarreia. Esse trabalho objetivou integrar os conhecimentos sobre esta bactéria emergente, descrever suas principais formas de virulência e verificar a presença dos genes cdtA, cdtB e cdtC em amostras de C. jejuni isoladas de cecos de aves, por meio da técnica de PCR. De todas as amostras, 100% (13/13) foram positivas para o gene cdtA, 84,6% (11/13) positivas para o gene cdtB e 92, 3% (12/13) positivas para o gene cdtC . 84,6% das amostras foram positivas para os três genes. Foi possível verificar a presença dos genes de virulência cdtA, cdtB e cdtC nas amostras estudas, por meio da técnica de PCR. Os resultados encontrados estão de acordo com a literatura, que relata variações próximas a 100% na prevalência destes genes nas amostras pesquisadas; não obstante, é necessária a análise de um maior número de amostras para verificar a importância e o aparecimento destes genes nos isolados no Brasil. Além da presença dos genes, o presente trabalho também visou discorrer sobre formas de interpretação da presença dos genes de virulência, por meio do emprego da inteligência artificial, mais especificamente, das redes neurais artificiais (RNA’s).Campylobacteriosis is a zoonosis of worldwide distribution that causes gastroenteritis in humans. The occurrence of food outbreaks caused by bacteria of the genus Campylobacter has been linked to consumption of animal products, especially those of poultry origin. This bacteria expresses genes that encode virulence factors that promote colonization and the occurrence of events that subvert host's physiology. Genes cdtA, cdtB and cdtC encode protein CDT (Cytolethal distending toxin), considered one of the major virulence factors of Campylobacter jejuni, which contributes to diarrhea occurrence. This study aimed to integrate the knowledge about this emerging bacteria, describe its main forms of virulence and verify (by using PCR technique) the presence of genes cdtA, cdtB and cdtC in samples of C. jejuni isolated from poultry caecal. From the samples, 100% (13/13) were positive for the gene cdtA, 84.6% (11/13) positive for the gene cdtB and 92, 3% (12/13) positive for the gene cdtC. 84.6% of samples were positive for all three genes. It was possible to verify the occurrence of virulence genes cdtA, cdtB and cdtC in the analyzed samples. These results are consistent with literature, that reports a variation close to 100% in the prevalence of these genes in the samples studied. Nevertheless, it is necessary an analysis of a larger sample to verify the occurrence and relevance of these genes in isolates in Brazil. Besides the presence of genes, this study also aimed at discussing ways of interpreting the presence of virulence genes through the use of artificial intelligence, more specifically, artificial neural networks (ANN)

Avaliação dos efeitos da dexametasona em órgãos do sistema imune - timo e bursa de fabricius- e em jejuno de frangos.

A integridade do sistema imune e do trato gastrointestinal está diretamente relacionada à sanidade das aves e ao desempenho zootécnico. Com intenção de melhor compreender estes sistemas e sua interação, o presente estudo foi desenvolvido. O objetivo do trabalho foi avaliar os efeitos da dexametasona nos órgãos linfoides - timo e bursa de Fabricius (BF) - e nas estruturas do jejuno, relacionando-os entre si e ao peso final dos animais. Para tal, foram utilizadas 33 amostras de BF, timo e intestinos, os quais foram processados histologicamente e corados com H&E. As lâminas de BF e de timo foram avaliadas por pelo menos dois histopatologistas, sendo utilizada a moda para determinar o escore de depleção de cada amostra. Foram obtidas fotomicrografias digitais de dez vilosidades por jejuno, nas quais mensuraram-se o comprimento e a largura de vilo e a profundidade de uma cripta associada, a altura de núcleo de enterócito, o comprimento de núcleo e a altura de microvilosidade. As medições foram realizadas no Software Motic 2.0®. Após, foram aplicados testes estatísticos paramétricos, utilizando o Software SPSS e o Software JMP-SAS. Observou-se a média de 4,20g nas BF de aves controles, ao passo que em animais submetidos à dexametasona a média 0,74g (p0,05). Intestinos de aves controles apresentaram comprimento em média 1366,4μm maiores e largura de vilosidades em média 58,4μm maiores que aves submetidas a tratamento (p0,05). Control poultry intestines showed, in average, 1366,4μm larger length, and 58,4μm higher mean width villi than poultry submitted to treatment (p<0,05). Treated poultry obtained 15,3% of weight gain in one week after finished the treatment, while control poultry presented 26,7% of weight gain in the same period. Between thymus weight and BF weight we obtained 93,1% correlation and regression coefficient (r2) of 86,7%. Likewise, between thymus weight and poultry weight the r2 was 86,4%. Among BF weight and poultry weight, we observed r2 of 71,8%. On the other hand, the parameters evaluated in the intestines showed no significant correlation. Length of villi and thymus weight presented correlation close to 50% and r2 of 22.5%. In this study, it was possible to evaluate the immunosuppressive effects of dexamethasone in thymus, BF and jejunum structures. There was reduction in weight gain in poultry treated with dexamethasone. It was possible to correlate lymphoid depletion and final weight of poultry. Correlation between villi length and thymus weight was also demonstrated

Resistência antimicrobiana em amostras de Salmonella hadar isoladas de carcaças de frango

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Estabelecimento de uma nova metodologia para a avaliação de depleção linfóide folicular da bolsa de Fabricius através da análise digital de imagem e de redes neurais artificiais

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