Electrospinning and biocompatibility evaluation of biodegradable polyurethanes based on L-lysine diisocyanate and L-lysine chain extender.

A series of biodegradable polyurethanes (PUs) were synthesized using poly(ε-caprolactone) diol (PCL) to react with L-lysine ethyl ester diisocyanate (LDI) chain extend with L-lysine ethyl ester (LEE) in solution of DMF. The structure was characterized by gel permeation chromatography, ¹H-NMR, Fourier transform infrared, and DSC analyses. Mechanical property testing showed that their tensile strength rose with increasing the hard segment content with a maximum tensile strength of 34.43 ± 1.73 MPa. The average mass loss for the hydrolytic degradation was only about 13 % in 56 days while this value for the enzymatic degradation was around 95 % in 30 days. The morphological and biomechanical characters of the tubular scaffolds electrospun from the as-prepared PUs were also examined. As the solution concentration was varied from 10 to 18% (w/v), the fiber diameter was progressively increased, and the scaffold tensile strength was enhanced from 2.82 ± 0.16 MPa to 7.07 ± 0.44 MPa, the suture retention strength from 2.48 ± 0.33 to 8.38 ± 0.35 N, and the burst pressure strength from 72 ± 2 to 172 ± 2 kPa, all higher than those of native blood vessels. At the same time, the L-929 mouse fibroblasts (L-929) and human umbilical vein endothelial cells were used in cytotoxicity and cell-adhesion evaluations toward the electrospun scaffolds. The level of toxicity is less than level 1, and cells were found to attach well to and remain viable on the scaffolds.

[Diagnosis and treatment of partial anomalous pulmonary venous connection].

OBJECTIVE: To explore the diagnosis and treatment of partial anomalous pulmonary venous connection (PAPVC). METHODS: The clinical data of 38 pediatric patients with PAPVC were retrospectively reviewed. All received ultrasonography and part of them received angiography or 64-detector spiral computed tomography. Then the enlarged atrial septal was repaired with patch to separate the pulmonary vein dystopia to left atrium or the vertical vein was anastomosed to left atrium directly or by homograft vessel. The complicating abnormalities were corrected. Follow-up was conducted for 3 months to 7 years. RESULTS: One case died from severe low cardiac output after operation. Two cases were complicated postoperatively with II degree atrial ventricular block and one with pulmonary hypertensive crisis, and all were cured after treatment. And the other patients recovered after surgery. Follow-up showed that the quality of their postoperative life was good and no relapse to obstruction of pulmonary venous was reported. CONCLUSION: Missed diagnosis always occur in PAPVC, the debauche and blood flow of pulmonary vein should be overviewed carefully during ultrasonographic examination. Transesophageal echocardiography and contrast examination may help. CT and MRI elevate the final diagnosis rate of PAPVC. The result of operation on PAPVC is good.