RESUMO

This study investigated the effect of a probiotic (Bacillus subtilis DSM 17299), blend of acidifiers, and their combination on the performance of broiler chicks. Two hundred and twenty unsexed one-day-old broilers (Ross 308) were randomly distributed into four groups (55 birds per group divided into 5 replicates) as 2X2 factorial arrangement including two factors, probiotic and blend of acidifiers, each of which had two levels: yes and no. Performance was determined weekly. Haemagglutination test was performed on blood samples taken on days 28 and 42 after the birds were injected twice (days 14 and 28) with 10% suspension of sheep red blood cells (SRBC). On day 42, tissue samples taken from the duodenum, jejunum and ileum were prepared for histology via scanning electron microscopy. During the first three weeks, dietary addition of probiotic significantly (p<0.05) increased body weight gain (BWG) while acidifiers significantly lowered (p<0.01) feed conversion ratio (FCR). Antibody titer against SRBC increased remarkably (p<0.01) 15 days post the first injection when probiotic was administered. The probiotic also increased (p<0.01) the number of the duodenal goblet cells, and the density of jejunal and ileal villi. Overall, the supplementation of probiotic or acidifiers enhanced the growth performance of broiler chicks, mainly during the first three weeks of age. The probiotic also improved the immune response and intestinal morphology of broilers. However, there was no evidence of synergy when probiotic and acidifiers were co-administered.(AU)

Assuntos

RESUMO

This study investigated the effect of a probiotic (Bacillus subtilis DSM 17299), blend of acidifiers, and their combination on the performance of broiler chicks. Two hundred and twenty unsexed one-day-old broilers (Ross 308) were randomly distributed into four groups (55 birds per group divided into 5 replicates) as 2X2 factorial arrangement including two factors, probiotic and blend of acidifiers, each of which had two levels: yes and no. Performance was determined weekly. Haemagglutination test was performed on blood samples taken on days 28 and 42 after the birds were injected twice (days 14 and 28) with 10% suspension of sheep red blood cells (SRBC). On day 42, tissue samples taken from the duodenum, jejunum and ileum were prepared for histology via scanning electron microscopy. During the first three weeks, dietary addition of probiotic significantly (p<0.05) increased body weight gain (BWG) while acidifiers significantly lowered (p<0.01) feed conversion ratio (FCR). Antibody titer against SRBC increased remarkably (p<0.01) 15 days post the first injection when probiotic was administered. The probiotic also increased (p<0.01) the number of the duodenal goblet cells, and the density of jejunal and ileal villi. Overall, the supplementation of probiotic or acidifiers enhanced the growth performance of broiler chicks, mainly during the first three weeks of age. The probiotic also improved the immune response and intestinal morphology of broilers. However, there was no evidence of synergy when probiotic and acidifiers were co-administered.

Assuntos

RESUMO

The atrioventricular (AV) node is permanently damaged in approximately 3 percent of congenital heart surgery operations, requiring implantation of a permanent pacemaker. Improvements in pacemaker design and in alternative treatment modalities require an effective in vivo model of complete heart block (CHB) before testing can be performed in humans. Such a model should enable accurate, reliable, and detectable induction of the surgical pathology. Through our laboratory’s efforts in developing a tissue engineering therapy for CHB, we describe here an improved in vivo model for inducing chronic AV block. The method employs a right thoracotomy in the adult rabbit, from which the right atrial appendage may be retracted to expose an access channel for the AV node. A novel injection device was designed, which both physically restricts needle depth and provides electrical information via electrocardiogram interface. This combination of features provides real-time guidance to the researcher for confirming contact with the AV node, and documents its ablation upon formalin injection. While all animals tested could be induced to acute AV block, those with ECG guidance were more likely to maintain chronic heart block >12 h. Our model enables the researcher to reproduce both CHB and the associated peripheral fibrosis that would be present in an open congenital heart surgery, and which would inevitably impact the design and utility of a tissue engineered AV node replacement.

Assuntos

RESUMO

The atrioventricular (AV) node is permanently damaged in approximately 3% of congenital heart surgery operations, requiring implantation of a permanent pacemaker. Improvements in pacemaker design and in alternative treatment modalities require an effective in vivo model of complete heart block (CHB) before testing can be performed in humans. Such a model should enable accurate, reliable, and detectable induction of the surgical pathology. Through our laboratory's efforts in developing a tissue engineering therapy for CHB, we describe here an improved in vivo model for inducing chronic AV block. The method employs a right thoracotomy in the adult rabbit, from which the right atrial appendage may be retracted to expose an access channel for the AV node. A novel injection device was designed, which both physically restricts needle depth and provides electrical information via electrocardiogram interface. This combination of features provides real-time guidance to the researcher for confirming contact with the AV node, and documents its ablation upon formalin injection. While all animals tested could be induced to acute AV block, those with ECG guidance were more likely to maintain chronic heart block >12 h. Our model enables the researcher to reproduce both CHB and the associated peripheral fibrosis that would be present in an open congenital heart surgery, and which would inevitably impact the design and utility of a tissue engineered AV node replacement.

Assuntos

Assuntos

RESUMO

A 15 month-old Quarter Horse colt developed severe bacterial pneumonia and effusive pleuritis. A beta-hemolytic streptococcus was isolated from a tracheal wash specimen but the colt died despite conventional therapy. The gross post mortem and histologic lesions were characteristic of pulmonary nocardiosis. Nocardia brasiliensis was isolated from the lung and bronchial lymph node.

Assuntos

RESUMO

Administration of high-dose (250 mg/kg) cyclophosphamide (CY) to guinea-pigs and mice 3 days prior to immunization with inactivated vaccine derived from Venezuelan encephalitis virus (VE), Coxiella burnetii and Francisella tularensis resulted in accentuated and prolonged delayed-type hypersensitivity (DTH) and in vitro cellular immunity (CMI) to specific antigen. Humoral antibody were either absent or significantly lower in CY-pretreated animals compared to immunized non-pretreated controls. CY pretreatments precluded protection in the VE virus model, suggesting that resistance is related to antibody. In the Q fever model, the protective immunogenicity of vaccine was preserved or increased by CY pretreatment suggesting that cell-mediated immunity is the important factor. In the tularaemia bacterial system, there was a complex effect of CY pretreatment on the low-grade protection afforded by killed vaccine against virulent infection. These findings suggest that the inability of killed vaccines to induce high-grade resistance against tularaemia and Q fever may be due in part to a suppressive B cell response which is eliminated by CY. These studies have given useful information on the relative significance of components of the specific immune response and may lead to an increased understanding of the mechanisms of action of vaccines and adjuvants.

Assuntos

RESUMO

Polyriboinosinic.polyribocytidylic acid [poly(I).poly(C)] stabilized with poly-l-lysine and carboxymethylcellulose [poly(ICLC)] has been previously shown to be a compound with marked adjuvant activity when given in high doses with inactivated Venezuelan equine encephalomyelitis (VEE) virus vaccine. This study investigated the effects of much lower doses of poly(ICLC) on the magnitude and kinetics of the primary and secondary humoral antibody responses of rhesus monkeys to inactivated VEE virus vaccine. Monkeys given a single injection of vaccine developed very low neutralizing antibody titers, whereas those given adjuvant plus vaccine had 30- to 100-fold-higher titers which remained elevated for longer than 6 months. Low doses of poly(ICLC) given with VEE virus vaccine resulted in a profound but transient increase in priming of secondary antibody responses to the antigen. In contrast, the administration of poly-l-lysine and carboxymethylcellulose alone without the poly(I).poly(C) component of the complex had no adjuvant effect on antibody responses of monkeys to VEE virus vaccine. The temporal development of antibody by class (immunoglobulin M-immunoglobulin G) in monkeys given two injections of adjuvant-vaccine was not different from that with vaccine alone. Serial hematological and clinical chemistry determinations on monkeys given single or multiple doses of poly(ICLC) with vaccine were not different from values in monkeys given vaccine alone.

Assuntos