Leukocytes respiratory burst and lysozyme level in pacu (Piaractus mesopotamicus Holmberg, 1887)

Respostas imunológicas inatas são úteis para determinar o estado de saúde de peixes e avaliar o efeito de substâncias imunomoduladoras no cultivo destes animais. A atividade respiratória de leucócitos foi medida em pacu (Piaractus mesopotamicus) através de ensaio de quimioluminescência e ensaio de redução do nitroblue tetrazolium (NBT). O ensaio de redução do nitroblue tetrazolium pareceu mais adequado que o ensaio de quimioluminescência para determinação da atividade respiratória de leucócitos, uma vez que foi difícil isolar com êxito os leucócitos do sangue para o ensaio de quimioluminescência. Lisozima sérica e plasmática foram medidas por meio de ensaio turbidimétrico. Com o objetivo de inativar as proteínas do sistema complemento, as amostras de soro e plasma foram aquecidas (56 ºC por 30 minutos). Porém, este procedimento provocou a turvação das amostras de plasma e interferiu nos resultados. A atividade de lisozima no soro foi maior que no plasma, sugerindo que amostras de soro são mais apropriadas para esta análise. Este estudo estabeleceu protocolos que podem ser utilizados como ferramentas no estudo de mecanismos imunológicos do peixe tropical pacu.Innate immune responses are useful to determine the health status of fish and to evaluate the effect of immunomodulatory substances in fish farming. Leukocytes respiratory burst was measured in pacu (Piaractus mesopotamicus) using chemiluminescence assay and nitroblue tetrazolium (NBT) reduction assay. The nitroblue tetrazolium reduction seemed more adequate than chemiluminescence assay for leukocytes oxidative burst determination, since it was difficult to isolate the blood leucocytes for chemiluminescence assay. Plasma and serum lysozyme were measured using a turbidimetric assay. The heating of serum and plasma samples (56 ºC for 30 minutes) for complement system inactivation darkened the plasma samples and interfered in the results. The lysozyme activity in serum was higher than in plasma, suggesting that serum samples are more appropriate for the analysis. This study established protocols that can be useful tools in the study of immune mechanisms of the tropical fish pacu.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Leukocytes respiratory burst and lysozyme level in pacu (Piaractus mesopotamicus Holmberg, 1887)

Innate immune responses are useful to determine the health status of fish and to evaluate the effect of immunomodulatory substances in fish farming. Leukocytes respiratory burst was measured in pacu (Piaractus mesopotamicus) using chemiluminescence assay and nitroblue tetrazolium (NBT) reduction assay. The nitroblue tetrazolium reduction seemed more adequate than chemiluminescence assay for leukocytes oxidative burst determination, since it was difficult to isolate the blood leucocytes for chemiluminescence assay. Plasma and serum lysozyme were measured using a turbidimetric assay. The heating of serum and plasma samples (56 ºC for 30 minutes) for complement system inactivation darkened the plasma samples and interfered in the results. The lysozyme activity in serum was higher than in plasma, suggesting that serum samples are more appropriate for the analysis. This study established protocols that can be useful tools in the study of immune mechanisms of the tropical fish pacu

Disease resistance of pacu Piaractus mesopotamicus (Holmberg, 1887) fed with β-glucan

Effects of β-glucan on innate immune responses and survival were studied in pacu experimentally infected with Aeromonas hydrophila. Fish fed diets containing 0, 0.1% and 1% β-glucan were injected with A. hydrophila. β-glucan enhanced fish survival in both treated groups (26.7% and 21.2% of the control, respectively). Leukocyte respiratory burst and alternative complement pathway activities were elevated after bacterial challenge regardless the β-glucan concentration. Lysozyme activity was higher after infection and showed a gradual increase as β-glucan concentration increased. A significant elevation in WBC count was observed either after bacterial challenge or by influence of β-glucan separately. The same response was observed in the number of thrombocytes, lymphocytes, eosinophils, LG-PAS positive cell and monocytes. It can be concluded that feeding pacu with β-glucan can increase protection against A. hydrophila, due to changes in non-specific immune responses

Development of prednisone: Polyethylene glycol 6000 fast-release tablets from solid dispersions: Solid-state characterization, dissolution behavior, and formulation parameters

The aim of the current study was to design oral fast-release polymeric tablets of prednisone and to optimize the drug dissolution profile by modifying the carrier concentration. Solid dispersions were prepared by the solvent evaporation method at different drug:polymer ratios (wt/wt). The physical state and drug:carrier interactions were analyzed by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. The dissolution rate of prednisone from solid dispersions was markedly enhanced by increasing the polymer concentration. The tablets were prepared from solid dispersion systems using polyethylene glycol (PEG) 6000 as a carrier at low and high concentration. The results showed that PEG 6000-based tablets exhibited a significantly higher prednisone dissolution (80% within 30 minutes) than did conventional tablets prepared without PEG 6000 (<25% within 30 minutes). In addition, the good disintegration and very good dissolution performance of the developed tablets without the addition of superdisintegrant highlighted the suitability of these formulated dosage forms. The stability studies performed in normal and accelerated conditions during 12 months showed that prednisone exhibited high stability in PEG 6000 solid dispersion powders and tablets. The X-ray diffraction showed that the degree of crystallinity of prednisone in solid dispersions decreased when the ratio of the polymer increased, suggesting that the drug is present inside the samples in different physical states. The Fourier transform infrared spectroscopic studies showed the stability of prednisone and the absence of well-defined drug:polymer interactions. Scanning electron microscopy images showed a novel morphology of the dispersed systems in comparison with the pure components