Jiang-Qin Liu

Cyclosporine treatment improves cardiac function and systemic hemodynamics during resuscitation in a newborn piglet model of asphyxia: a dose-response study.

Objectives:Asphyxiated neonates often have myocardial depression, which is a significant cause of morbidity and mortality. Cardioprotective effects of cyclosporine have been observed in adult patients and animals with myocardial infarction. However, the cardioprotective effect of cyclosporine in neonates has not yet been studied. We hypothesize that cyclosporine will improve cardiac function and reduce myocardial injury in asphyxiated newborn piglets. Design:Thirty-six piglets (1–4 days old, weighing 1.4–2.5 kg) were acutely instrumented for continuous monitoring of cardiac output and systemic arterial pressure. After stabilization, normocapnic alveolar hypoxia (10% to 15% oxygen) was instituted for 2 hrs followed by reoxygenation with 100% oxygen for 0.5 hrs and then 21% for 3.5 hrs. A nonasphyxiated, sham-operated group was included (n = 4) to control for effects of the surgical model. Plasma troponin and myocardial lactate concentrations were determined as well as morphologic examinations. Setting:Neonatal asphyxia and reoxygenation. Subjects:Newborn (1–4 days old) piglets. Interventions:Piglets were block-randomized to receive intravenous boluses of cyclosporine A (2.5, 10, or 25 mg/kg) or normal saline (control) at 5 mins of reoxygenation (n = 8/group). Measurements and Main Results:Cardiac index, heart rate, systemic oxygenation, plasma troponin, and left ventricular lactate were measured. Hypoxic piglets had cardiogenic shock (cardiac output 40% to 48% of baseline), hypotension (mean arterial pressure 27–31 mm Hg), and acidosis (pH 7.04). Cyclosporine treatment caused bell-shaped improvements in cardiac output, stroke volume, and systemic oxygen delivery (p < .05 vs. controls). Plasma troponin and left ventricle lactate were higher in controls than that of 2.5 and 10 mg/kg cyclosporine-treated groups (p < .05). Although histologic features of myocardial injury were not different among groups, severe damage was observed in mitochondria of control piglets but attenuated in that of cyclosporine (10 mg/kg) treatment. Conclusions:Postresuscitation administration of cyclosporine causes preservation of cardiac function and attenuates myocardial injury in newborn piglets after asphyxia–reoxygenation. (Crit Care Med 2012; 40:–1244)

Effects of tanshinone IIA, a major component of Salvia miltiorrhiza, on platelet aggregation in healthy newborn piglets

ETHNOPHARMACOLOGICAL RELEVANCE Tanshinone IIA (STS), an active ingredient of the Chinese herb Danshen (Salvia miltiorrhiza) for angina and stroke in adults, has been reported to inhibit platelet function. However, its effect on platelet and underlying mechanism remain largely unknown, particularly in neonates. MATERIALS AND METHODS To investigate the effect of STS on the platelet aggregation and its interaction with various platelet activation pathways, platelet aggregatory function was studied in whole blood stimulated by collagen (2-10 μg/ml) ex vivo in newborn piglets receiving intravenous STS (0.1-10mg/kg, n=8) and in vitro in whole blood from newborn piglets (n=6) incubated with STS (0.1-100 μg/ml). The respective morphological changes of platelets were also examined by scanning electron microscopy. Plasma levels of nitrite/nitrate (NOx) and thromboxane B(2) (TxB(2)), matrix metalloproteinase (MMP)-2 and -9 activities were also examined. To further delineate the mechanistic pathway, the effect of STS on endothelial microparticles release from cultured human umbilical vein endothelial cells (HUVECs) was quantified by flow cytometry. RESULTS STS impaired the ex vivo, but not in vitro, collagen-stimulated platelet aggregation. Infusion of STS elevated the plasma level of TxB(2) at 10mg/kg. However, STS had no effect on NOx level. Incubating cultured HUVECs with STS (1 and 10 μg/ml) caused a significant release of endothelial microparticles. Morphologically, STS elicited platelet activation in vivo, but not in vitro. CONCLUSIONS STS impairs the ex vivo whole blood platelet aggregatory function by activating platelet in vivo in healthy newborn piglets. It implies that STS may elicit its effects by stimulating endothelial microparticles production and eicosanoid metabolism pathway.

N-Acetylcysteine Improves Hemodynamics and Reduces Oxidative Stress in the Brains of Newborn Piglets with Hypoxia-Reoxygenation Injury

Reactive oxygen species have been implicated in the pathogenesis of hypoxic-ischemic injury. It has been shown previously that treating an animal with N-acetyl-L-cysteine (NAC), a scavenger of free radicals, significantly minimizes hypoxic-ischemic-induced brain injury in various acute models. Using a subacute swine model of neonatal hypoxia-reoxygenation (H-R), we evaluated the long-term beneficial effect of NAC against oxidative stress-induced brain injury. Newborn piglets were randomly assigned to a sham-operated group (without H-R, n = 6), and two H-R experimental groups (n = 8 each), with 2 h normocapnic alveolar hypoxia and 1 h of 100% oxygen reoxygenation followed by 21% oxygen for 47 h. Five minutes after reoxygenation, the H-R piglets received either normal saline (H-R controls) or NAC (150 mg/kg bolus and 20 mg/kg/h IV for 24 h) in a blinded randomized fashion. Treating the piglets with NAC significantly increased both common carotid arterial flow (CCAF) and oxygen delivery during the early phase of rexoygenation, while both CCAF and carotid oxygen delivery of the H-R group remained lower than the sham-operated groups throughout the experimental period. Compared with H-R controls, significantly higher amounts of anesthetic and sedative medications were required to maintain the NAC-treated piglets in stable condition throughout the experimental period, indicating a stronger recovery. Post-resuscitation NAC treatment also significantly attenuated the increase in cortical caspase-3 and lipid hydroperoxide concentrations. Our findings suggest that post-resuscitation administration of NAC reduces cerebral oxidative stress with improved cerebral oxygen delivery, and probably attenuates apoptosis in newborn piglets with H-R insults.

Sodium tanshinone IIA sulfonate increased intestinal hemodynamics without systemic circulatory changes in healthy newborn piglets

In traditional Chinese medicine, tanshinone IIA is a lipid-soluble component of Danshen that has been widely used for various cardiovascular and cerebrovascular disorders, including neonatal asphyxia. Despite promising effects, little is known regarding the hemodynamic effects of tanshinone IIA in newborn subjects. To examine the dose-response effects of sodium tanshinone IIA sulfonate (STS) on systemic and regional hemodynamics and oxygen transport, 12 newborn piglets were anesthetized and acutely instrumented for the placement of femoral arterial and venous, pulmonary arterial catheters to measure mean arterial, central venous, and pulmonary arterial pressures, respectively. The blood flow at the common carotid, renal, pulmonary, and superior mesenteric (SMA) arteries were continuously monitored after treating the piglets with either STS (0.1-30 mg/kg iv) or saline treatment (n = 6/group). To further delineate the underlying mechanisms for vasorelaxant effects of STS, in vitro vascular myography was carried out to compare its effect on rat mesenteric and carotid arteries (n = 4-5/group). STS dose-dependently increased the SMA blood flow and the corresponding oxygen delivery with no significant effect on systemic and pulmonary, carotid and renal hemodynamic parameters. In vitro studies also demonstrated that STS selectively dilated rat mesenteric but not carotid arteries. Vasodilation in mesenteric arteries was inhibited by apamin and TRAM-34 (calcium-activated potassium channel inhibitors) but not by meclofenamate (cyclooxygenase inhibitor) or N-nitro-l-arginine methyl ester hydrochloride (nitric oxide synthase inhibitor). In summary, without significant hemodynamic effects on newborn piglets, intravenous infusion of STS selectively increased mesenteric perfusion in a dose-dependent manner, possibly via an endothelium-derived hyperpolarizing factor vasodilating pathway.

Postresuscitation cyclosporine treatment attenuates myocardial and cardiac mitochondrial injury in newborn piglets with asphyxia-reoxygenation.

Objectives:Cardiovascular dysfunction occurs in the majority of asphyxiated neonates and has been suggested to be a major cause of neonatal morbidity and mortality. We previously demonstrated that cyclosporine A treatment during resuscitation can significantly improve cardiovascular performance in asphyxiated newborn piglets. However, the mechanisms through which cyclosporine elicits its protective effect in neonates have not yet been fully characterized. We hypothesized that cyclosporine A treatment would attenuate myocardial and cardiac mitochondrial injury during the resuscitation of asphyxiated newborn piglets. Design:After acute instrumentation, piglets received normocapnic alveolar hypoxia (10% to 15% oxygen) for 2 hours followed by reoxygenation with 100% oxygen (0.5 hr) and then 21% oxygen (3.5 hr). At 4 hours of reoxygenation, plasma troponin level, left ventricle myocardial levels of lipid hydroperoxides, cytochrome-c, and mitochondrial aconitase activity were determined. Setting:Neonatal asphyxia and reoxygenation. Subjects:Twenty-four newborn (1–4 days old) piglets. Interventions:Piglets were randomized to receive an IV bolus of cyclosporine A (10 mg/kg) or normal saline (placebo, control) at 5 minutes of reoxygenation (n = 8/group). Sham-operated piglets (n = 8) underwent no asphyxia-reoxygenation. Measurements and Main Results:Asphyxiated piglets treated with cyclosporine had lower plasma troponin and myocardial lipid hydroperoxides levels (vs. controls, both p < 0.05, analysis of variance). Cyclosporine treatment also improved mitochondrial aconitase activity and attenuated the rise in cytosol cytochrome-c level (vs. controls, all p < 0.05). The improved mitochondrial function significantly correlated with cardiac output (p < 0.05, Spearman rank-correlation test). Conclusions:We demonstrate that the postresuscitation administration of cyclosporine attenuates myocardial and cardiac mitochondrial injury in asphyxiated newborn piglets following resuscitation.

Cyclosporine treatment reduces oxygen free radical generation and oxidative stress in the brain of hypoxia-reoxygenated newborn piglets.

Oxygen free radicals have been implicated in the pathogenesis of hypoxic-ischemic encephalopathy. It has previously been shown in traumatic brain injury animal models that treatment with cyclosporine reduces brain injury. However, the potential neuroprotective effect of cyclosporine in asphyxiated neonates has yet to be fully studied. Using an acute newborn swine model of hypoxia-reoxygenation, we evaluated the effects of cyclosporine on the brain, focusing on hydrogen peroxide (H2O2) production and markers of oxidative stress. Piglets (1–4 d, 1.4–2.5 kg) were block-randomized into three hypoxia-reoxygenation experimental groups (2 h hypoxia followed by 4 h reoxygenation)(n = 8/group). At 5 min after reoxygenation, piglets were given either i.v. saline (placebo, controls) or cyclosporine (2.5 or 10 mg/kg i.v. bolus) in a blinded-randomized fashion. An additional sham-operated group (n = 4) underwent no hypoxia-reoxygenation. Systemic hemodynamics, carotid arterial blood flow (transit-time ultrasonic probe), cerebral cortical H2O2 production (electrochemical sensor), cerebral tissue glutathione (ELISA) and cytosolic cytochrome-c (western blot) levels were examined. Hypoxic piglets had cardiogenic shock (cardiac output 40–48% of baseline), hypotension (mean arterial pressure 27–31 mmHg) and acidosis (pH 7.04) at the end of 2 h of hypoxia. Post-resuscitation cyclosporine treatment, particularly the higher dose (10 mg/kg), significantly attenuated the increase in cortical H2O2 concentration during reoxygenation, and was associated with lower cerebral oxidized glutathione levels. Furthermore, cyclosporine treatment significantly attenuated the increase in cortical cytochrome-c and lactate levels. Carotid blood arterial flow was similar among groups during reoxygenation. Conclusively, post-resuscitation administration of cyclosporine significantly attenuates H2O2 production and minimizes oxidative stress in newborn piglets following hypoxia-reoxygenation.

Effects of post-resuscitation treatment with N-acetylcysteine on cardiac recovery in hypoxic newborn piglets.

Aims Although N-acetylcysteine (NAC) can decrease reactive oxygen species and improve myocardial recovery after ischemia/hypoxia in various acute animal models, little is known regarding its long-term effect in neonatal subjects. We investigated whether NAC provides prolonged protective effect on hemodynamics and oxidative stress using a surviving swine model of neonatal asphyxia. Methods and Results Newborn piglets were anesthetized and acutely instrumented for measurement of systemic hemodynamics and oxygen transport. Animals were block-randomized into a sham-operated group (without hypoxia-reoxygenation [H–R, n = 6]) and two H-R groups (2 h normocapnic alveolar hypoxia followed by 48 h reoxygenation, n = 8/group). All piglets were acidotic and in cardiogenic shock after hypoxia. At 5 min after reoxygenation, piglets were given either saline or NAC (intravenous 150 mg/kg bolus + 20 mg/kg/h infusion) via for 24 h in a blinded, randomized fashion. Both cardiac index and stroke volume of H-R controls remained lower than the pre-hypoxic values throughout recovery. Treating the piglets with NAC significantly improved cardiac index, stroke volume and systemic oxygen delivery to levels not different from those of sham-operated piglets. Accompanied with the hemodynamic improvement, NAC-treated piglets had significantly lower plasma cardiac troponin-I, myocardial lipid hydroperoxides, activated caspase-3 and lactate levels (vs. H-R controls). The change in cardiac index after H-R correlated with myocardial lipid hydroperoxides, caspase-3 and lactate levels (all p<0.05). Conclusions Post-resuscitation administration of NAC reduces myocardial oxidative stress and caused a prolonged improvement in cardiac function and in newborn piglets with H-R insults.

Sequential Changes of Hemodynamics and Blood Gases in Newborn Piglets With Developing Pneumothorax

Little information is available regarding the temporal changes in hemodynamics and blood gases during the development of a moderate pneumothorax in a neonate. In this study, we aim to investigate the temporal changes of hemodynamics and arterial blood gases in a neonatal swine model of unilateral pneumothorax.

Improved renal recovery with postresuscitation N-acetylcysteine treatment in asphyxiated newborn pigs.

Renal injury is one of the severe and common complications that occurs early in neonates with asphyxia, and reactive oxygen species have been implicated to play an important role on its pathogenesis. Improved renal recovery has been shown previously with N-acetyl-l-cysteine (NAC) in various acute kidney injuries. Using a subacute swine model of neonatal hypoxia-reoxygenation (H/R), we examined whether NAC can sustain its beneficial effect on renal recovery for 48 h. Newborn piglets were randomly assigned into a sham-operated group (without H/R, n = 6) and two H/R experimental groups (n = 8 each) with 2 h normocapnic alveolar hypoxia and 1 h 100% oxygen of reoxygenation followed by 21% oxygen for 47 h. Five minutes after reoxygenation, piglets received either normal saline (H/R control) or NAC (150-mg/kg bolus and 20 mg/kg per hour i.v. for 24 h) in a blinded, randomized fashion. All piglets were acidotic and in cardiogenic shock after hypoxia. Treating the piglets with NAC significantly increased both renal blood flow and oxygen delivery throughout the reoxygenation period. N-acetyl-l-cysteine treatment also improved the renal function with the attenuation of elevated urinary N-acetyl-&bgr;-d-glucosaminidase activity and plasma creatinine concentration observed in H/R controls (both P < 0.05). The tissue levels of lipid hydroperoxides and caspase 3 in the kidney of NAC-treated animals were significantly lower than those of H/R controls. Conclusively, postresuscitation administration of NAC elicits a prolonged beneficial effect in improving renal functional recovery and reducing oxidative stress in newborn piglets with H/R insults for 48 h.

Infusing Sodium Bicarbonate Suppresses Hydrogen Peroxide Accumulation and Superoxide Dismutase Activity in Hypoxic-Reoxygenated Newborn Piglets

Background The effectiveness of sodium bicarbonate (SB) has recently been questioned although it is often used to correct metabolic acidosis of neonates. The aim of the present study was to examine its effect on hemodynamic changes and hydrogen peroxide (H2O2) generation in the resuscitation of hypoxic newborn animals with severe acidosis. Methods Newborn piglets were block-randomized into a sham-operated control group without hypoxia (n = 6) and two hypoxia-reoxygenation groups (2 h normocapnic alveolar hypoxia followed by 4 h room-air reoxygenation, n = 8/group). At 10 min after reoxygenation, piglets were given either i.v. SB (2 mEq/kg), or saline (hypoxia-reoxygenation controls) in a blinded, randomized fashion. Hemodynamic data and blood gas were collected at specific time points and cerebral cortical H2O2 production was continuously monitored throughout experimental period. Plasma superoxide dismutase and catalase and brain tissue glutathione, superoxide dismutase, catalase, nitrotyrosine and lactate levels were assayed. Results Two hours of normocapnic alveolar hypoxia caused cardiogenic shock with metabolic acidosis (pH: 6.99±0.07, HCO3 −: 8.5±1.6 mmol/L). Upon resuscitation, systemic hemodynamics immediately recovered and then gradually deteriorated with normalization of acid-base imbalance over 4 h of reoxygenation. SB administration significantly enhanced the recovery of both pH and HCO3− recovery within the first hour of reoxygenation but did not cause any significant effect in the acid-base at 4 h of reoxygenation and the temporal hemodynamic changes. SB administration significantly suppressed the increase in H2O2 accumulation in the brain with inhibition of superoxide dismutase, but not catalase, activity during hypoxia-reoxygenation as compared to those of saline-treated controls. Conclusions Despite enhancing the normalization of acid-base imbalance, SB administration during resuscitation did not provide any beneficial effects on hemodynamic recovery in asphyxiated newborn piglets. SB treatment also reduced the H2O2 accumulation in the cerebral cortex without significant effects on oxidative stress markers presumably by suppressing superoxide dismutase but not catalase activity.