Zhengyuan Xia

Large-dose propofol during cardiopulmonary bypass decreases biochemical markers of myocardial injury in coronary surgery patients: a comparison with isoflurane.

We investigated if increasing propofols dosage to augment its antioxidant capacity during cardiopulmonary bypass (CPB) could confer cardiac protection. Fifty-four coronary artery bypass graft surgery patients were randomly assigned to small-dose propofol (Group P; n = 18), large-dose propofol (Group HiP; n = 18), or isoflurane Group (Group I; n = 18). After the induction, anesthesia was maintained with an inspired concentration of isoflurane 1%–3.5% (Group I) or a continuous infusion of propofol 60 &mgr;g · kg−1 · min−1 (Group P) throughout the surgery. In Group HiP, this dose of propofol was increased to 120 &mgr;g · kg−1 · min−1 for 10 min before the onset of CPB until 15 min after aortic unclamping and then decreased to 60 &mgr;g · kg−1 · min−1 until the end of surgery. The duration of aortic cross-clamping was 83 ± 24, 88 ± 22, and 81 ± 20 min in Group P, Group HiP, and Group I, respectively (P > 0.1). Plasma malondialdehyde, a marker of oxidative stress, was significantly lower at 8 h after CPB, and Troponin I was lower at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05). There was a significant reduction in inotropic requirements for separation from CPB in Group HiP compared with Group I. Postoperative systemic vascular resistance was significantly reduced in Group HiP as compared with Group I. Mean cardiac index was significantly higher at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05) (Group I, 2.2 ± 0.1; Group P, 2.3 ± 0.2; and Group HiP, 2.8 ± 0.3 L · min−1 · m−2, respectively). The duration of intensive care unit stay was significantly shorter in Group Hi-P compared with Group I. We conclude that administration of a large dose of propofol during CPB attenuates postoperative myocardial cellular damage as compared with isoflurane or small-dose propofol anesthesia.

GWAS3D: detecting human regulatory variants by integrative analysis of genome-wide associations, chromosome interactions and histone modifications

Interpreting the genetic variants located in the regulatory regions, such as enhancers and promoters, is an indispensable step to understand molecular mechanism of complex traits. Recent studies show that genetic variants detected by genome-wide association study (GWAS) are significantly enriched in the regulatory regions. Therefore, detecting, annotating and prioritizing of genetic variants affecting gene regulation are critical to our understanding of genotype–phenotype relationships. Here, we developed a web server GWAS3D to systematically analyze the genetic variants that could affect regulatory elements, by integrating annotations from cell type-specific chromatin states, epigenetic modifications, sequence motifs and cross-species conservation. The regulatory elements are inferred from the genome-wide chromosome interaction data, chromatin marks in 16 different cell types and 73 regulatory factors motifs from the Encyclopedia of DNA Element project. Furthermore, we used these function elements, as well as risk haplotype, binding affinity, conservation and P-values reported from the original GWAS to reprioritize the genetic variants. Using studies from low-density lipoprotein cholesterol, we demonstrated that our reprioritizing approach was effective and cell type specific. In conclusion, GWAS3D provides a comprehensive annotation and visualization tool to help users interpreting their results. The web server is freely available at http://jjwanglab.org/gwas3d.

Hyperglycemia-Induced Protein Kinase C β2 Activation Induces Diastolic Cardiac Dysfunction in Diabetic Rats by Impairing Caveolin-3 Expression and Akt/eNOS Signaling

Protein kinase C (PKC)β2 is preferably overexpressed in the diabetic myocardium, which induces cardiomyocyte hypertrophy and contributes to diabetic cardiomyopathy, but the underlying mechanisms are incompletely understood. Caveolae are critical in signal transduction of PKC isoforms in cardiomyocytes. Caveolin (Cav)-3, the cardiomyocyte-specific caveolar structural protein isoform, is decreased in the diabetic heart. The current study determined whether PKCβ2 activation affects caveolae and Cav-3 expression. Immunoprecipitation and immunofluorescence analysis revealed that high glucose (HG) increased the association and colocalization of PKCβ2 and Cav-3 in isolated cardiomyocytes. Disruption of caveolae by methyl-β-cyclodextrin or Cav-3 small interfering (si)RNA transfection prevented HG-induced PKCβ2 phosphorylation. Inhibition of PKCβ2 activation by compound CGP53353 or knockdown of PKCβ2 expression via siRNA attenuated the reductions of Cav-3 expression and Akt/endothelial nitric oxide synthase (eNOS) phosphorylation in cardiomyocytes exposed to HG. LY333531 treatment (for a duration of 4 weeks) prevented excessive PKCβ2 activation and attenuated cardiac diastolic dysfunction in rats with streptozotocin-induced diabetes. LY333531 suppressed the decreased expression of myocardial NO, Cav-3, phosphorylated (p)-Akt, and p-eNOS and also mitigated the augmentation of O2−, nitrotyrosine, Cav-1, and iNOS expression. In conclusion, hyperglycemia-induced PKCβ2 activation requires caveolae and is associated with reduced Cav-3 expression in the diabetic heart. Prevention of excessive PKCβ2 activation attenuated cardiac diastolic dysfunction by restoring Cav-3 expression and subsequently rescuing Akt/eNOS/NO signaling.

Propofol enhances ischemic tolerance of middle-aged rat hearts: effects on 15-F2t-isoprostane formation and tissue antioxidant capacity

OBJECTIVE Experimental study has shown that myocardial ischemic tolerance is reduced during middle-age. We investigated the effect of propofol on ischemic tolerance of middle-aged rat hearts. METHODS Hearts of young adult (10 weeks old, Y) and middle-aged rats (20 weeks old, M) were assigned to propofol (P-Y, P-M) and control (C-Y, C-M) groups (n=6 each). Hearts were perfused using a Langendorff preparation with Krebs-Henseleit solution (KH) at constant flow rates. We applied propofol (P-Y, P-M) for 10 min at 12 microg/ml before inducing 40 min global ischemia. During ischemia, saline (C-Y, C-M) or propofol (P-Y, P-M) in saline was perfused through the aorta at 60 microl/min. Propofol in KH was perfused at 12 microg/ml for the first 15 min of reperfusion and subsequently reduced to 5 microg/ml in propofol treatment groups. Coronary effluent was assayed for 15-F(2t)-isoprostane after equilibration, during ischemia (T(1)) and at 0.5 (T(2)) and 5 (T(3)) min of reperfusion. After 90 min of reperfusion (T(4)), hearts were harvested to assess tissue antioxidant capacity. RESULTS In P-Y, we observed an increased latency to ischemic-contracture and a significantly reduced contracture after 35 min ischemia compared to control groups. No ischemic contracture was observed in P-M. There were significantly lower 15-F(2t)-isoprostane levels in P-M and P-Y than in C-M and C-Y at T(1). At T(4), the recovery of left ventricular developed pressure in P-M was greater than in P-Y (P<0.05); both were greater than in C-M and C-Y. CONCLUSION Propofol enhanced ischemic tolerance of middle-aged hearts, primarily by inhibiting lipid peroxidation.

GWASdb v2: an update database for human genetic variants identified by genome-wide association studies

Genome-wide association studies (GWASs), now as a routine approach to study single-nucleotide polymorphism (SNP)-trait association, have uncovered over ten thousand significant trait/disease associated SNPs (TASs). Here, we updated GWASdb (GWASdb v2, http://jjwanglab.org/gwasdb) which provides comprehensive data curation and knowledge integration for GWAS TASs. These updates include: (i) Up to August 2015, we collected 2479 unique publications from PubMed and other resources; (ii) We further curated moderate SNP-trait associations (P-value < 1.0×10−3) from each original publication, and generated a total of 252 530 unique TASs in all GWASdb v2 collected studies; (iii) We manually mapped 1610 GWAS traits to 501 Human Phenotype Ontology (HPO) terms, 435 Disease Ontology (DO) terms and 228 Disease Ontology Lite (DOLite) terms. For each ontology term, we also predicted the putative causal genes; (iv) We curated the detailed sub-populations and related sample size for each study; (v) Importantly, we performed extensive function annotation for each TAS by incorporating gene-based information, ENCODE ChIP-seq assays, eQTL, population haplotype, functional prediction across multiple biological domains, evolutionary signals and disease-related annotation; (vi) Additionally, we compiled a SNP-drug response association dataset for 650 pharmacogenetic studies involving 257 drugs in this update; (vii) Last, we improved the user interface of website.

N-Acetylcysteine and allopurinol up-regulated the Jak/STAT3 and PI3K/Akt pathways via adiponectin and attenuated myocardial postischemic injury in diabetes

N-Acetylcysteine (NAC) and allopurinol (ALP) synergistically reduce myocardial ischemia reperfusion (MI/R) injury in diabetes. However, the mechanism is unclear. We postulated that NAC and ALP attenuated diabetic MI/R injury by up-regulating phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and Janus kinase 2/signal transducer and activator of transcription-3 (JAK2/STAT3) pathways subsequent to adiponectin (APN) activation. Control (C) or streptozotocin-induced diabetic rats (D) were untreated or treated with NAC and ALP followed by MI/R. D rats displayed larger infarct size accompanied by decreased phosphorylation of Akt, STAT3 and decreased cardiac nitric oxide (NO) and APN levels. NAC and ALP decreased MI/R injury in D rats, enhanced phosphorylation of Akt and STAT3, and increased NO and APN. High glucose and hypoxia/reoxygenation exposure induced cell death and Akt and STAT3 inactivation in cultured cardiomyocytes, which were prevented by NAC and ALP. The PI3K inhibitor wortmannin and Jak2 inhibitor AG490 abolished the protection of NAC and ALP. Similarly, APN restored posthypoxic Akt and STAT3 activation and decreased cell death in cardiomyocytes. Gene silencing with AdipoR2 siRNA or STAT3 siRNA but not AdipoR1 siRNA abolished the protection of NAC and ALP. In conclusion, NAC and ALP prevented diabetic MI/R injury through PI3K/Akt and Jak2/STAT3 and cardiac APN may serve as a mediator via AdipoR2 in this process.

Propofol Dose-Dependently Reduces Tumor Necrosis Factor--Induced Human Umbilical Vein Endothelial Cell Apoptosis: Effects on Bcl-2 and Bax Expression and Nitric Oxide Generation

We investigated whether propofol can inhibit tumor necrosis factor (TNF)-&agr;-induced apoptosis in cultured human umbilical vein endothelial cells (HUVECs). Isolated HUVECs were cultured in Dulbecco’s modified Eagle medium supplemented with 20% bovine calf serum. HUVECs in untreated and propofol control groups were cultured at 37°C for 24.5 h. HUVECs in the TNF treatment groups were initially cultured for 30 min in the presence of TNF or various concentrations of propofol, respectively, which were then cultured for 24 h with the addition of TNF at 40 ng/mL in the medium. Apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and confirmed by electron microscopy. The antiapoptotic Bcl-2 and proapoptotic Bax protein expressions were measured by immunocytochemical analysis. TNF stimulation resulted in a reduced Bcl-2/Bax ratio and increased apoptotic index (AI: percentage of apoptotic cells) in HUVECs. Propofol, at concentrations ≥12 &mgr;M, significantly (P < 0.001) and dose-dependently attenuated TNF-induced increase in AI and decrease in Bcl-2/Bax ratio. This was accompanied by increases in nitric oxide production. There is an inverse correlation between the ratio of Bcl-2/Bax expression and AI (P = 0.0009). These results suggest that propofol, at clinical relevant concentrations, can reduce TNF-induced HUVEC apoptosis.

Antioxidant therapy with Salvia miltiorrhiza decreases plasma endothelin-1 and thromboxane B2 after cardiopulmonary bypass in patients with congenital heart disease

OBJECTIVE The endothelium-derived vasoconstrictor endothelin-1 is increased after cardiopulmonary bypass in children with congenital heart defects. This study determines whether antioxidant therapy with Salvia miltiorrhiza injection, an herb extract containing phenolic compounds, prevents the postoperative increase of endothelin-1. The relationship between endothelin-1 and the endothelium-derived prostacyclin (prostaglandin I2) and thromboxane A2 postoperatively is also investigated. METHODS Twenty children with congenital heart defects and pulmonary hypertension were randomly assigned to group A (placebo control, n=10) or B (200 mg/kg Salvia miltiorrhiza intravenously after anesthesia induction and at the time of rewarming, respectively; n =10) before cardiac surgery. Central venous blood samples were taken before operation (T(0)), 10 (T(1)) and 30 minutes (T(2)) after starting cardiopulmonary bypass, 10 (T(3)) and 30 minutes (T(4)) after aortic declamping, and 30 minutes (T(5)) and 24 hours (T(6)) after termination of cardiopulmonary bypass. Plasma lipid peroxidation product malondialdehyde, myocardial specific creatine kinase-MB activity, thromboxane B2, and 6-keto-prostaglandin F(1 alpha) (stable metabolites of thromboxane A2 and prostaglandin I2) were measured. RESULTS Malondialdehyde increased significantly at T(1) in group A and remained significantly higher than in group B thereafter (P <.05). Malondialdehyde in group B did not significantly increase over time. At T(5), plasma creatine kinase-MB, thromboxane B2, and endothelin-1 in group B were lower than in group A (P <.05); malondialdehyde correlated significantly with creatine kinase-MB (r = 0.71, P =.0005). At T(6), endothelin-1 negatively correlated with the 6-keto-prostaglandin F(1 alpha)/thromboxane B2 ratio (r = -0.64, P =.0025). CONCLUSION Antioxidant therapy reduces myocardial damage and attenuates postoperative vasoactive mediator imbalance.

Synergy of isoflurane preconditioning and propofol postconditioning reduces myocardial reperfusion injury in patients

Either isoflurane preconditioning or high-dose propofol treatment has been shown to attenuate myocardial IRI (ischaemia/reperfusion injury) in patients undergoing CABG (coronary artery bypass graft) surgery. It is unknown whether isoflurane and propofol may synergistically attenuate myocardial injury in patients. The present study investigated the efficacy of IsoPC (isoflurane preconditioning), propofol treatment (postconditioning) and their synergy in attenuating postischaemic myocardial injury in patients undergoing CABG surgery using CPB (cardiopulmonary bypass). Patients (n = 120) selected for CABG surgery were randomly assigned to one of four groups (n = 30 each). After induction, anaesthesia was maintained either with fentanyl and midazolam (control; group C); with propofol at 100 μg x kg(-1) of body weight x min(-1) before and during CPB followed by propofol at 60 μg x kg(-1) of body weight x min(-1) for 15 min after aortic declamping (group P); with isoflurane 1-1.5% end tidal throughout the surgery (group I) or with isoflurane 1-1.5% end tidal before CPB and switching to propofol at 100 μg x kg(-1) of body weight x min(-1) during CPB followed by propofol at 60 μg x kg(-1) of body weight x min(-1) for 15 min after aortic declamping (group IP, i.e. IsoPC plus propofol postconditioning). A joint isoflurane and propofol anaesthesia regimen synergistically reduced plasma levels of cTnI (cardiac troponin I) and CK-MB (creatine kinase MB) and f-FABP (heart-type fatty acid-binding protein) (all P < 0.05 compared with control, group P or group I) and facilitated postoperative myocardial functional recovery. During reperfusion, myocardial tissue eNOS (endothelial NO synthase) protein expression in group IP was significantly higher, whereas nitrotyrosine protein expression was lower than those in the control group. In conclusion, a joint isoflurane preconditioning and propofol anaesthesia regimen synergistically attenuated myocardial reperfusion injury in patients.

Propofol Pretreatment Reduces Ceramide Production and Attenuates Intestinal Mucosal Apoptosis Induced by Intestinal Ischemia/Reperfusion in Rats

BACKGROUND:Apoptosis has been shown to be a major mode of intestinal epithelial cell death caused by intestinal ischemia/reperfusion (II/R), a condition that is associated with increased oxidative stress. Ceramide has been proposed as a messenger of apoptosis. We investigated if pretreatment with propofol, an anesthetic with antioxidant properties, could reduce ceramide production, and consequently, mucosal epithelial apoptosis induced by II/R in rats. METHODS:Rat II/R injury was produced by clamping the superior mesenteric artery for 1 h followed by 3 h of reperfusion. Thirty rats were randomly allocated into control, injury (II/R) and propofol (pretreatment) groups (n = 10 per group). In the propofol group, propofol 50 mg/kg, a dose that has been shown to cause the loss of reflex responses to a painful stimulus while remaining sensitive to skin incision in rats, was administered intraperitoneally 30 min before inducing intestinal ischemia, while animals in control and untreated injury groups received an equal volume of intralipid. Intestinal mucosal epithelial apoptosis was detected via electron microscopy and TUNEL analysis. Lipid oxidation product malondialdehyde and the activities of superoxide dismutase were assessed by colorimetric analyses. Ceramide generation and sphingomyelinase mRNA expression in intestinal mucosa were determined by high performance thin layer chromatography and reverse transcriptase polymerase chain reaction, respectively. RESULTS:II/R caused intestinal mucosal epithelial apoptosis and over-production of ceramide accompanied by up-regulation of sphingomyelinase mRNA expression and increases in lipid oxidation (all P < 0.01 versus control). Propofol pretreatment significantly attenuated these changes (all P < 0.01, propofol versus injury). CONCLUSION:The findings indicate that propofol pretreatment attenuates II/R-induced intestinal epithelial apoptosis, which might be attributable to its antioxidant property modulating the ceramide pathway.