Small-diameter PCL/PU vascular graft modified with heparin-aspirin compound for preventing the occurrence of acute thrombosis.

The occurrence of acute thrombosis, directly related to platelet aggregation and coagulant system, is a considerable reason for the failure of small-diameter vascular grafts. Heparin is commonly used as a functional molecule for graft modification due to the strong anticoagulant effect. Unfortunately, heparin cannot directly resist the adhesion and aggregation of platelets. Therefore, we have prepared a heparin-aspirin compound by coupling heparin with aspirin, an antiplatelet drug, and covalently grafted it onto the surface of polycaprolactone/polyurethane composite tube. In this way, the graft not only showed a dual function of both anticoagulation and antiplatelet, but also effectively avoided the rapid drug release and excessive toxicity to other organs caused by simple blending the medicine with material matrix. The compound retained the original function of heparin, showing good hydrophilicity and biocompatibility, which could promote the adhesion and proliferation of endothelial cells (ECs) and facilitate the process of tissue regeneration. What's more, the compound showed more effective than heparin in reducing platelet activation and preventing thrombosis. The graft modified by this compound maintained completely unobstructed for one month of implantation, while severe obstruction or stenosis occurred in PCL/PU and PCL/PU-Hep lumen at the first week, verifying the effect of the compound on preventing acute thrombosis. In general, this study proposed a designing method for small-diameter vascular graft which could prevent acute thrombosis and promote intimal construction.

Observation of the fluorescence spectrum for a driven cascade model system in atomic beam.

We experimentally study the resonance fluorescence from an excited two-level atom when the atomic upper level is coupled by a nonresonant field to a higher-lying state in a rubidium atomic beam. The heights, widths and positions of the fluorescence peaks can be controlled by modifying the detuning of the auxiliary field. We explain the observed spectrum with the transition properties of the dressed states generated by the coupling of the two laser fields. We also attribute the line narrowing to the effects of Spontaneously Generated Coherence between the close-lying levels in the dressed state picture generated by the auxiliary field. And the corresponding spectrum can be viewed as the evidence of Spontaneously Generated Coherence. The experimental results agree well with calculations based on the density-matrix equations.

A biomimetic orthogonal-bilayer tubular scaffold for the co-culture of endothelial cells and smooth muscle cells.

In blood vessels, endothelial cells (ECs) grow along the direction of blood flow, while smooth muscle cells (SMCs) grow circumferentially along the vessel wall. To mimic this structure, a polycaprolactone (PCL) tubular scaffold with orthogonally oriented bilayer nanofibers was prepared via electrospinning and winding. ECs were cultured on the inner layer of the scaffold with axial nanofibers and SMCs were cultured on the outer layer of the scaffold with circumferential nanofibers. Fluorescence images of the F-actin distribution of ECs and SMCs indicated that cells adhered, stretched, and proliferated in an oriented manner on the scaffold. Moreover, layers of ECs and SMCs formed on the scaffold after one month of incubation. The expression levels of platelet-endothelial cell adhesion molecule 1 (PECAM-1) and a contractile SMC phenotype marker in the EC/SMC co-culture system were much higher than those in individual culture systems, thus demonstrating that the proposed biomimetic scaffold promoted the intercellular junction of ECs and preserved the contractile phenotype of SMCs.

[Impact of viable myocardium assessed by 99Tcm-MIBI SPECT and 18F-FDG PET imaging on clinical outcome of patients with left ventricular aneurysm underwent revascularization].

OBJECTIVE: To evaluate the impact of viable myocardium assessed by (99)Tc()m-MIBI SPECT and (18)F-fluorodeoxyglucose (FDG) PET imaging in patients with left ventricular aneurysm (LVA) underwent revascularization (RVS). METHODS: Forty-six consecutive patients with LVA (mean LVEF 36% +/- 7%), underwent (99)Tc(m)-sestamibi SPECT and (18)F-FDG PET examinations and received RVS therapy, were followed-up for a mean period of 80 +/- 27 months. Viable myocardium in aneurysm was defined as perfusion-metabolism mismatch score (MMS) >/= 2.0. Patients were divided into four groups by aneurysm viability and aneurysmectomy. Group A1 (n = 8): viability-; Group A2 (n = 15): viability-, aneurysmectomy; Group B1 (n = 10): viability +; and Group B2 (n = 13): viability +, aneurysmectomy. RESULTS: The cardiac event rates during follow up were similar among groups [A1 (25%, 2/8), B1 (40%, 6/15), A2 (20%, 2/10) and B2 (31%, 4/13; P > 0.05)]. After revascularization, LVEF was improved (> 10%) in groups A2, B1 and B2 (P < 0.05). Multivariate logistic regression analysis showed that LV-MMS (OR = 2.34, 95% CI 1.08 - 5.06, P < 0.05), distal vessel disease (OR = 0.008, 95% CI 0.001 - 0.560, P < 0.05) and nonaneurysm perfusion score (OR = 0.24, 95% CI 0.07 - 0.85, P < 0.05) were significantly associated with the improvement of LVEF after revascularization. CONCLUSIONS: Long term cardiac events rate post revascularization was not affected by viable myocardium or aneurysmectomy in LVA patients. Viable myocardium in LVA patients was associated with better LVEF improvement after revascularization.

[Surgical treatment of flail leaflet of tricuspid valve].

OBJECTIVE: To explore the approach and the result in tricuspid valve insufficiency treatment by a cusp remodeling technique. METHODS: Nine patients with severe tricuspid regurgitation, congenital lack of chordae in 6 cases and traumatic rupture of chordae in 3 cases, underwent surgical repair between April 1997 and March 2006. There were six male and three female. Their ages ranged from 8 years to 57 years. One or two segments of flail leaflets were presented in these patients. Valve repair was performed by suture of the free edge of the affected cusp segment, plication of the segment of annulus devoid of leaflet, and fixation of the neo-annulus with a flexible annuloplasty ring. RESULTS: All patients survived and recovered after the operation. Echocardiography showed good coaptation with no regurgitation of the tricuspid valve in six patients and a mild residual tricuspid regurgitation in three. A remarkable decrease in the diameter of the right ventricle (anterior to posterior) was observed: from mean (43.6 +/- 4.2) mm (range 29 mm to 64 mm) preoperatively reducing to mean (24.0 +/- 1.8) mm (range 16 mm to 32 mm) postoperatively. All patients are doing well in 1 month to 109 months follow up. CONCLUSION: The procedure provided a simple and valuable option for repair of flail leaflet of tricuspid valve caused by congenital lack of chordae or traumatic rupture of chordae.

[Arterial switch operation in older infants with severe pulmonary hypertension].

OBJECTIVE: To investigate the clinical efficacy of arterial swith operation on transposition of great artery (TGA) and Tausing-Bing anomaly. METHODS: Between June 2000 and December 2002, 30 consecutive patients, aged 3 days to 6 years (mean, 9.4 +/- 15 months) with the mean body weight was 6.1 kg +/- 2.7 kg, underwent arterial switch operation. Among the 30 patients 7 suffered from TGA with intact ventricular septum, 19 from TGA with ventricular septal defect (VSD), 3 from Taussing-Bing anomaly, and 1 from corrected TGA; 12 were complicated by atrial septal defect (ASD) and 18 complicated by patent ductus arteriosus (PDA); 23 had severe pulmonary hypertension; 2 had left ventricular outlet stenosis. Coronary type A distribution was recognized in 26 cases, type D in 4, and one of them having the origin of the left descending artery tunneled in the aortic wall. The operation was performed under general anesthesia and extracorporeal circulation with low temperature and low volume blood flow. Prostaglandin 1 was administered pre-operatively in 3 patients, one of which underwent balloon atrial septostomy and one underwent pulmonary banding and systemic to pulmonary shunt pre-operatively. The aorta and pulmonary artery were transected above the valvular commisures, the coronary ostia with all the adjacent sinus of Valsalva were excised and re-implanted to the proximal neo-aorta, and then aortic anastomosis was completed. The proximal neo-pulmonary trunk was reconstructed with a large autologous native pericardium as a posterior patch. The pulmonary anastomosis was completed after the aortic cross-clamp was released. The VSD was repaired through the atrium or proximal aorta with dacron patches. RESULTS: Two patients died with a hospital mortality rate of 6.7%. No death was directly related to any coronary artery problem. One 5 day-old neonate with TGA and an intact septum having refractory hypotension, hypoxemia, and acidosis pre-operatively underwent a smooth emergency operation. The patient had a refractory low cardiac output syndrome post-operatively and died 20 hours after the operation. Another patient with chylothorax died of allergy from iodophor 22 days postoperatively. The pulmonary pressure decreases significantly in 22 patients who had severe pulmonary hypertension preoperatively with the mean pressure 46.7 mm Hg preoperatively and 31.3 mm Hg postoperatively. 28 patients were discharged from hospital uneventfully. Follow-up of 1 to 31 months showed survival with no late complications and death. CONCLUSION: The arterial switch procedure has a satisfying effect on TGA for patients older than 1 month with severe pulmonary hypertension.

[Anatomic repair of congenitally corrected transposition of the great artery by double switch operation: two cases report].

OBJECTIVE: To report two patients with congenitally corrected transposition of the great artery were performed double switch operation. METHODS: Two patients with corrected transposition of the great artery underwent double switch operation. One was 9-month years old boy, associated with ventricular septal defect (VSD), pulmonary artery hypertension. He had senning procedure and artery switch operation (ASO). The other was a 23 years old man, associated with VSD, tricuspid valve regurgitation, and pulmonary stenosis. He had senning procedure and Rastelli operation. RESULTS: There was no operation death, one got heart block before operation requiring pacemaker. The echo of postoperation showed the patients had normal ventricle function and there were no stenosis of tunnel and conduit, no tricuspid valve regurgitation. CONCLUSION: Double switch operation is a good option for congenitally corrected transposition of the great artery.

[Induced tolerance to cardiac allografts with multiple intravenous injection of donor spleen cells].

OBJECTIVE: To study the methods and mechanisms of immune tolerance in cardiac transplantation. METHODS: Male DA rat hearts were transplanted to male Lewis rats using Ono's model and randomly divided into five groups: untreated, intravenous injection of 1 x 10(8) DA splenocytes to Lewis rat, intraperitoneal injection of cyclophosphamide (100 mg/kg) to Lewis rat, intravenous injection of 1 x 10(8) DA splenocytes combined with intraperitoneal injection of cyclophosphamide (100 mg/kg) to Lewis rat, multiple injection of DA rat splenocytes with intraperitoneal injection of cyclophosphamide, 11 days later heart transplantation was performed. Mean survival time (MST), histological changes, mixed lymphocyte reaction (MLR), the role of interleukin-2 (IL-2) to MLR and the role of tolerant rat splenocytes to MLR were measured after operation. RESULTS: The survival time of heart allografts in the group of multiple injection of DA rat splenocytes with intraperitoneal injection of cyclophosphamide [MST: (85.3 +/- 7.5) d, t = 0, P < 0.01] was significantly longer than in the groups of untreated [MST: (7.3 +/- 1.0) d], intravenous injection of 1 x 10(8) DA splenocytes to Lewis rat [MST: (7.9 +/- 0.9) d], intraperitoneal injection of cyclophosphamide (100 mg/kg) to Lewis rat [MST: (8.1 +/- 1.2) d], intravenous injection of 1 x 10(8) DA splenocytes combined with intraperitoneal injection of cyclophosphamide (100 mg/kg) to Lewis rat [MST: (25.8 +/- 3.5) d]. Only a few inflammatory cells infiltrated in cardiac allografts in the group of multiple injection of DA rat splenocytes with intraperitoneal injection of cyclophosphamide. MLR in the group of multiple injection of DA rat splenocytes with intraperitoneal injection of cyclophosphamide were significantly decreased compared with those of normal control (t = 0, P < 0.01). IL-2 could partly reversed the hyporesponsiveness of MLR in tolerant rats, the tolerance could be transferred in vitro. CONCLUSIONS: Multiple injection of donor splenocytes combined with intraperitoneal injection of cyclophosphamide to recipients could induce immune tolerance to cardiac allografts.

[Cytocompatibility of PBS/PLA blend as the sternal fixation material].

UNLABELLED: To evaluate biocompatibility and cytotoxicity of PBS/PLA blend as the material for sternal fixation. METHODS: L929 cell line was used to assess the cytotoxicity and cytocompatibility of PBS/PLA blend by incubation of the cells with the aqueous extract of the material for 3 days. The cytocompatibility of the material was evaluated by observing the proliferation of the cells cultured on the surface of the material. The proliferation of the cells cultured on the surface of the material was compared with that of the cells cultured on medical polyethylene and polyvinyl chloride to assess the cytotoxicity of the material. RESULTS: L929 cells showed no morphological changes after a 3-day incubation with the aqueous extract of the material. The cells cultured on the surface of the blend material exhibited better proliferative activity than those cultured on medical polyethylene and polyvinyl chloride, demonstrating no obvious cytotoxicity of the material. CONCLUSION: PBS/PLA blend material possesses excellent cytocompatibility and can be a promising biodegradable polymer for sternal fixation.