[Efficacy of volume-targeted ventilation for the treatment of neonatal respiratory distress syndrome].

OBJECTIVE: To investigate the efficacy of volume-targeted ventilation (VTV) for the treatment of neonatal respiratory distress syndrome (NRDS). METHODS: Fifty-two neonates with NRDS between August 2013 and August 2015 were randomly divided into two groups: VTV and pressure-controlled ventilation (PCV) (n=26 each ). A/C+Vc+ ventilation model was applied in the VTV group, and A/C+PCV ventilation model was applied in the PCV group. Arterial blood gas analysis was performed at 6, 24, and 48 hours after ventilation. The following parameters were observed: time of invasive ventilation, duration of oxygen therapy, mortality, and the incidence rates of hypocapnia, pneumothorax, ventilator-associated pneumonia (VAP), grade III-IV periventricular-intraventricular hemorrhage (PVH-IVH), periventricular leukomalacia (PVL), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP). RESULTS: Compared with the PCV group, the VTV group had a significantly shorter time of invasive ventilation (P<0.05) and significantly lower incidence rates of hypocapnia, VAP, and PVL (P<0.05); however, there were no significant differences in the duration of oxygen therapy, mortality, and incidence rates of pneumothorax, grade III-IV PVH-IVH, BPD, and ROP. CONCLUSIONS: VTV has a better efficacy than PCV in the treatment of NRDS, and is worthy of clinical promotion and application.

L-type calcium channel blocker suppresses calcineurin signal pathway and development of right ventricular hypertrophy.

BACKGROUND AND PURPOSE: Many studies have shown that L-type calcium channel blockers can prevent and treat right ventricular hypertrophy (RVH). In order to identify the mechanism, we investigated the role of the calcineurin signal pathway in the progression of RVH induced by chronic hypoxia and the effects of an L-type calcium channel blocker on the pathway. METHODS: Rats were allocated to 1 of 3 groups (n=10 for each): chronic hypoxia group, amlodipine treatment group (30 mg/kg/day, administered via gavage); and control group. Rats in the amlodipine treatment group and the chronic hypoxia group were exposed to normobaric chronic hypoxia (9.5%-10.5% oxygen). We investigated the changes of right ventricle (RV) to left ventricle (LV) and interventricular septum (S) weight ratio [RV/(LV+S)], RV to body weight (BW) ratio (RV/BW), calcineurin A beta (CnAbeta) mRNA levels, cardiac myosin heavy chain beta (beta-MHC) mRNA levels and protein expression of CnAbeta, nuclear factor 3 of activated T cell (NFAT3), and beta-MHC. RESULTS: After 21 days, RV/(LV+S) and RV/BW were significantly higher in the chronic hypoxia group than in the control group and the amlodipine group (p<0.01). The expression of CnAbeta mRNA and protein, NFAT3 protein, beta-MHC mRNA and protein in RV of the chronic hypoxia group was higher than that of the control group and the amlodipine treatment group (p<0.01). CONCLUSIONS: The calcineurin signal pathway plays a critical role in the progression of RVH induced by chronic hypoxia. L-type calcium channel blockade suppresses the development of RVH by inhibiting this pathway.

[Effect of cyclosporine A on myocardial calcineurin activity of the right ventricle and plasma NO, nitric oxide synthase and endothelin-1 levels in rats with chronic hypoxia].

OBJECTIVE: To study the role of calcineurin in the progression of right ventricle myocardial hypertrophy in rats exposed to chronic hypoxia by examining the effect of Ca(2+) channel blockers on the activation of calcineurin and plasma levels of nitric oxide (NO), NO synthase, and endothelin-1 (ET-1). METHODS: Rat models of right ventricle myocardial hypertrophy were established by exposing the rats to chronic hypoxia in 10.0%+/-0.5% O(2) for 7 d. The 24 rat models were assigned into normoxic group, hypoxic group and cyclosporin A (CsA)-treated hypoxic group. The rats in normoxic group were kept under normoxic environment, while those in the other 2 groups were subjected to further hypoxic treatment for 14 d, with the rats in CsA group receiving intraperitoneal CsA injection at 20 mg/kg on a daily basis. On day 21 of the experiment, all the rats were killed to collect the hearts for measuring the weight ratio of the right ventricle to the left ventricle and interventricular septum [RV/ LV+S ], as well as the right ventricle to body weight ratio (RV/BW); blood samples were also drawn from the ventricles for measuring plasma NO, iNOS, and ET-1 levels, with the ventricular myocardial [Ca(2+)](i) and the activity of calcineurin also determined. RESULTS: The RV/(LV+S) and RV/BW were significantly higher in hypoxic group than those of the normoxic and CsA groups (P<0.01); the right ventricular myocardial [Ca(2+)](i) in CsA group was significantly higher than that in the other two groups (P<0.01). In comparison with the normoxic group, the right ventricular myocardial calcineurin activity was significantly increased in the hypoxic group. CsA treatment significantly suppressed calcineurin activity (P<0.01). CONCLUSIONS: Calcineurin possibly plays a role in the progression of right ventricle myocardial hypertrophy in rats with chronic hypoxia. Blocking L-type Ca(2+) channels with CsA effectively prevents the development of myocardial hypertrophy possibly by inhibiting calcium influx and suppressing calcineurin activity.