S-Nitrosylation of Prostacyclin Synthase Instigates Nitrate Cross-Tolerance In Vivo.

Development of nitrate tolerance is a major drawback to nitrate therapy. Prostacyclin (PGI2) is a powerful vasodilator produced from prostaglandin (PGH2) by prostacyclin synthase (PGIS) in endothelial cells. This study aimed to determine the role of PGIS S-nitrosylation in nitrate tolerance induced by nitroglycerin (GTN). In endothelial cells, GTN increased PGIS S-nitrosylation and disturbed PGH2 metabolism, which were normalized by mutants of PGIS cysteine 231/441 to alanine (C231/441A). Clearance of nitric oxide by carboxy-PTIO or inhibition of S-nitrosylation by N-acetyl-cysteine decreased GTN-induced PGIS S-nitrosylation. Enforced expression of mutated PGIS with C231/441A markedly abolished GTN-induced PGIS S-nitrosylation and nitrate cross-tolerance in Apoe-/- mice. Inhibition of cyclooxygenase 1 by aspirin, supplementation of PGI2 by beraprost, and inhibition of PGIS S-nitrosylation by N-acetyl-cysteine improved GTN-induced nitrate cross-tolerance in rats. In patients, increased PGIS S-nitrosylation was associated with nitrate tolerance. In conclusion, GTN induces nitrate cross-tolerance through PGIS S-nitrosylation at cysteine 231/441.

Pravastatin activates activator protein 2 alpha to augment the angiotensin II-induced abdominal aortic aneurysms.

We have previously reported that activation of AMP-activated kinase alpha 2 (AMPKα2) by nicotine or angiotensin II (AngII) instigates formation of abdominal aortic aneurysms (AAA) in Apoe-/- mice. Statins, used to treat hyperlipidemia widely, activate AMPK in vascular cells. We sought to examine the effects of pravastatin on AAA formation and uncover the molecular mechanism. The AAA model was induced by AngII and evaluated by incidence, elastin degradation, and maximal abdominal aortic diameter in Apoe-/- mice. The phosphorylated levels of AMPKα2 and activator protein 2 alpha (AP-2α) were examined in cultured vascular smooth muscle cells (VSMCs) or in mice. We observed that pravastatin (50 mg/kg/day, 8 weeks) remarkably increased the AngII-induced AAA incidence in mice. In VSMCs, pravastatin increased the levels of pAMPK, pAP-2α, and MMP2 in both basal and AngII-stressed conditions, which were abolished by tempol and compound C. Pravastatin-upregulated MMP2 was abrogated by AMPKα2 or AP-2α siRNA. Lentivirus-mediated gene silence of AMPKα2 or AP-2α abolished pravastatin-worsened AAA formations in AngII-infused Apoe-/- mice. Clinical investigations demonstrated that both AMPKα2 and AP-2α phosphorylations were increased in AAA patients or human subjects taking pravastatin. In conclusion, pravastatin promotes AAA formation through AMPKα2-dependent AP-2α activations.

Effects of Ulinastatin on Perioperative Inflammatory Response and Pulmonary Function in Cardiopulmonary Bypass Patients.

The aim of this study was to investigate whether ulinastatin (UTL) has protective effects on perioperative proinflammatory cytokines and lung injury in cardiopulmonary bypass (CPB) patients. The study included 60 patients undergoing CPB who were randomly divided into a UTL group and a control group. Blood routine examination and inflammatory cytokines concentrations were detected after anesthetic induction (T1), immediately after aortic valve opening (T2), and 4 (T3) and 24 (T4) hours after weaning from CPB. Flow cytometry was used to detect TLR4 and HSP70 expressions. Arterial blood gas and respiratory function were analyzed at the same time points. Compared with the control group, the levels of IL-2, IL-8, TNF-α, NE, TLR4, PA - aDO2, and RI at T2 were significantly lower, whereas HSP70, PaO2, OI, Cd, and Cs were higher in the UTL group (all P < 0.05). Relative to the control group at T3, white blood cell count, TLR4, IL-2, IL-6, IL-8, TNF-α, NE, and RI decreased significantly, whereas IL-10, HSP70, PaO2, OI, and Cs increased in the UTL group (all P < 0.05). At T4, IL-2, IL-6, IL-8, TNF-α, TLR4, and PaCO2 in the UTL group were significantly lower, and PaO2, IL-10, HSP70, and Cs were higher than in the control group (all P < 0.05). Our data show strong evidence that UTL suppresses proinflammatory cytokine elevation and upregulates release of anti-inflammatory mediators, reducing pulmonary injury and improving pulmonary function after CPB.

A single-center experience of hemofiltration treatment for acute aortic dissection (Stanford type A) complicated with postoperative acute renal failure.

OBJECTIVE: To investigate the effect of continuous venovenous hemofiltration (CVVH) for aortic dissection patients with acute renal failure after surgery in retrospective manner. METHODS: A total of thirty-seven aortic dissection patients with postoperative acute renal failure accepted CVVH therapy. The effect of CVVH was evaluated by analyzing clinical condition changes and laboratory examination results. RESULTS: After treatment of CVVH, renal function and clinical symptoms were significantly improved in thirty patients. Eight of the thirty patients got completely renal function recovery within two weeks after CVVH therapy; and twenty-two of the thirty patients got completely renal function recovery within four weeks after CVVH therapy. Nevertheless, seven patients got no benefit from CVVH therapy with poor prognosis. CONCLUSION: CVVH is an effective treatment to most aortic dissection patients with postoperative acute renal failure. The effect of CVVH was correlated with original renal function, early CVVH therapy, and continuous intensive care.

Mesenchymal stem cells differentiate into an endothelial phenotype, reduce neointimal formation, and enhance endothelial function in a rat vein grafting model.

Autologous vein grafts is still commonly used for arterial reconstructive procedures. Their success is limited by the development of neointimal hyperplasia. Clinical and experimental evidence suggest that the bone marrow derived mesenchymal stem cells (MSCs) participate in the neovascularization. The current study used a direct approach to test the hypothesis that, after vein grafting in a rat model, MSCs have potential effects on reendothelialization and neointimal formation. MSCs were isolated by bone marrow cell adherence. Autologously interpositioning left external jugular vein (LEJV) to left common carotid artery-induced vein grafting model of r at w as utilized. Vascular lesion formation after transplantation of MSCs labeled with 4',6-diamidino-2-phenylindole (DAPI) was investigated. Two weeks after implantation, immunofluorescence studies revealed that engrafted cells acquired an endothelial phenotype, and some expressed endothelial nitric oxide synthase (eNOS). Furthermore, proliferation of cells and neointimal formation decreased significantly after MSC implantation. Real-time reverse transcription-PCR and western blotting analysis showed a rise of eNOS expression in the MSC group compared with the vein grafting group. Therefore, engrafted MSCs appeared to differentiate into endothelial cells, diminish the neointima formation and contribute to the improvement on endothelial function, which indicates that MSCs may exert an important function as repair mechanism in vascular injury after vein grafting.

[Effects of immunosuppressive treatment in prevention of calcification in aortic valved homograft: experiment with rats].

OBJECTIVE: To investigate the effects of immunosuppressive treatment in prevention of calcification in aortic valved homograft (AVH). METHODS: 120 Wistar rats were randomly divided into 4 equal groups: Group A (allogene group) undergoing incision of the abdominal aorta and implantation of the AVH with myocardial cuff from SD rats, Group B, injected with cyclosporine A intraperitoneally one day after the implantation, Group C, injected intraperitoneally with anti-dendritic cell monoclonal antibody (DCmAb) one day after the implantation, and Group D (isogenenic or control group), receiving the AVH of another Wistar rats. All groups were further subdivided into 5 equal subgroups to be sacrificed at different time points: 2, 4, 8, 12, and 16 weeks postoperatively. Blood samples were obtained from the vena cava to detect the expression of T-cell antigen receptor (TCR)-alpha and beta and CD28 by flow cytometry. AVH specimens were obtained to observe the changes of endotheliocytes and smooth muscle cells with light and electron microscopy. The expression of CD54 was detected by immunohistochemistry. The calcium content of the AVH tissue after transplantation was examined by flame atomic absorption spectrophotometry. RESULTS: (1) Compared with the isogenic group, the expression levels of TCR-alpha and beta and CD28 in the allogener groups were all significantly higher at all time points (all P < 0.01), peaked 2 approximately 4 weeks after operation, then gradually decreased, and approached the level of the controls 12 weeks after the implantation. Specifically, the expression levels of TCR-alpha and TCR-beta 2 and 4 weeks postoperatively of Group A were 52.4% +/- 3.3% and 43.8% +/- 6.4% respectively, significantly higher than those of Group B [(34.5 +/- 3.5)% and (31.6 +/- 2.6)% respectively], Group C [(31.6 +/- 2.3)% and (29.5 +/- 3.0)% respectively), and Group D (23.2 +/- 1.3)% and (21.6 +/- 2.3)% (all P < 0.01)]; and the CD28 expression level 2 approximately 4 weeks after operation of Group A were (51.7 +/- 7.5)% and (66.3 +/- 4.4)% respectively, both significantly higher than those of Group B [(41.2 +/- 1.6)% and (55.1 +/- 5.1)% respectively], Group C [(36.6 +/- 3.6)% and (51.8 +/- 5.6)% respectively], and Group D [30.7 +/- 1.4)% and (33.3 +/- 0.9)% respectively)] [all P < 0.01 except those levels 12 and 16 weeks after the operation in each subgroup (P > 0.05)] And the levels of TCR-alpha and TCR-beta and CD28 of the 2 treatment groups were all significantly lower than those of the untreated group (Group A) (all P < 0.01). (2) The calcium contents of the AVH tissues of Group A, B, and C significantly increased 4 weeks after the operation and peaked 12 and 16 weeks after operation. No significant difference in calcium level was found in Group D at different time points (all P > 0.05). The calcium contents in AVH tissues 4 and 8 weeks postoperatively of Groups A, B, and C were (2856 +/- 79) microg/g and (3587 +/- 168) microg/g respectively, (2518 +/- 73) microg/g, (3237 +/- 187) microg/g; and (2176 +/- 210) microg/g and (3089 +/- 176) microg/g; all significantly higher than those of Group D (860 +/- 60) microg/g and (870 +/- 50) microg/g respectively, all P < 0.01. CONCLUSION: Immunosuppressive treatment obviously reduces the immune rejection and delays the course of AVH calcification.

[Application of one-way valved patch in treatment of patients with congenital heart disease with severe pulmonary hypertension].

OBJECTIVE: To explore the effect of one-way valved patch used in congenital heart disease with severe pulmonary hypertension. METHODS: One-way valved patch was used in 30 patients of congenital heart disease with severe pulmonary hypertension (PP/PS > 0.75) in operation. Follow-up of 6 approximately 86 months was conducted to observe its effect. RESULTS: The pulmonary artery pressure was significantly decreased without trans-patch shunt in 11 cases postoperatively. Trans-patch shunt was determined in 27 cases within postperative 72 hours. There were 2 postoperative deaths out of these 27 patients: one died of low cardiac output syndrome 72 hours after operation, and the other died of right heart failure 4 weeks after operation. Thirty-six patients were restored to health and discharged. Three-month follow-up showed trans-patch shunt in 7 cases, including right-to left shunt in 4 cases and two-side shunt in other 3 cases. Color Doppler ultrasonography conducted 6 months after operation proved trans-patch shunt in 4 cases, right-to-left shunt in 1 case, two-side shunt in 2 cases, and left-to-right shunt in 1 case (PP/PS = 0.45). CONCLUSION: One-way valved patch is useful in selected patients in which postoperative right heart failure can be anticipated so as to shunt the blood in the right heart to the left heart and increase the blood volume in the left heart system to ensure the left heart output and minimize the risk of postoperative right heart failure, at the expense of systemic low oxygen saturation that is, however, well tolerated.