Objective To evaluate the impact of different doses of recombinant human B-type natriuretic peptid (rh-BNP) within the dosage of clinical rage on oxygen consumption during acute myocardial infarction (AMI) with heart failure (HF). Methods AMI-HF model of York pig was established by occluding coronary artery with balloon combined with in-jecting microthrombus. Then animals were randomized into rhBNP group and control group. Clinical dose of rhBNP ( 1.5μg/kg bolus followed by a continuous infusion with speed of 0.01, 0.02 and 0.03μg · kg-1 · min-1 for 60 minutes respectively in turn) was administrated in rhBNP group while equal volume of saline was given in the control group. Myocardial oxygen up-take (MOU) was measured by drawing blood from coronary artery and coronary sinus using a catheter. Coronary diameter was determined using quantitative coronary angiography. The observation points were at baseline (T0), instant after the mod-el establishment (T1), 60 min after continuous rhBNP infusion of 0.01, 0.02, 0.03μg·kg-1·min-1 (T2-T4) respectively. Re-sults Compared with the control group, pulmonary capillary wedge pressure, central venous pressure, heart rate, systolic blood pressure and MOU were significantly decreased after rhBNP administration. And cardiac output and coronary diame-ter were obviously increased with addition of rhBNP. There is a interaction of drug intervention and time. In rhBNP group, MOU was significantly decreased with drug administraion (T2-T4 vs T1,mL O2/L: 10.61 ± 0.35,9.85 ± 0.60,9.79 ± 0.31 vs 11.59 ± 0.37). Conclusion Intravenous administration of rhBNP in AMI-HF model could decrease MOU and PCWP while increase the cardiac output.

To obtain specific antibodies against nsp4 protein of porcine reproductive and respiratory syndrome virus (PRRSV), nsp4 gene was amplified by RT-PCR and cloned into pET-28a(+) vector, designated pET28a-nsp4. pET28a-nsp4 was transformed into Escherichia coli Trasseta (DE3) cells and expressed after induction of IPTG. SDS-PAGE analysis showed that the recombinant protein was expressed in soluble form with the molecular weight of 26 kDa. The soluble fusion protein in the supernatant was purified using Ni+-NTA affinity chromatography. New Zealand rabbits were immunized by the purified nsp4 and anti-sera against nsp4 were obtained. The titer of polyclonal antibodies was about 106 and showed good specificity and sensitivity in the immunofluorescence assay and Western blotting analysis. The polyclonal antibodies also recognized native nsp4 form PRRSV infected Marc-145 cells, providing a useful tool in PRRSV replication mechanism study.