Biodegradable poly(ester‐ether)s: ring‐opening polymerization of D,L‐3‐methyl‐1,4‐dioxan‐2‐one using various initiator systems

The synthesis and detailed characterization of racemic 3‐methyl‐1,4‐dioxan‐2‐one (3‐MeDX) are reported. The bulk ring‐opening polymerization of 3‐MeDX, to yield a poly(ester‐ether) meant for biomedical applications, in the presence of various initiators such as tin(II) octanoate, tin(II) octanoate/n‐butyl alcohol, aluminium tris‐isopropoxide and an aluminium Schiff base complex (HAPENAlOⁱPr) under varying experimental conditions is here detailed for the first time. Polymerization kinetics were investigated and compared with those of 1,4‐dioxan‐2‐one. The studies reveal that the rate of polymerization of 3‐MeDX is less than that of 1,4‐dioxan‐2‐one. Experimental conditions to achieve relatively high molar masses have been established. Thermodynamic parameters such as enthalpy and entropy of 3‐MeDX polymerization as well as ceiling temperature have been determined. Poly(D ,L ‐3‐MeDX) is found to possess a much lower ceiling temperature than poly(1,4‐dioxan‐2‐one). Poly(D ,L ‐3‐MeDX) was characterized using NMR spectroscopy, matrix‐assisted laser desorption ionization mass spectrometry, size exclusion chromatography and differential scanning calorimetry. This polymer is an amorphous material with a glass transition temperature of about ?20 °C. Copyright © 2010 Society of Chemical Industry     

Conversion from routine CPB to centrifugal mechanical assist by transaortic inflow cannulation of the left ventricle

We describe a technique of conversion from cardiopulmonary bypass to centrifugal mechanical assist that consists of using the existing aortic cannula for outflow and inserting a cannula into the left ventricle through a Dacron tube and across the aortic valve for inflow.     

Treatment of a persistent postoperative chylothorax with somatostatin

Chylothorax is a rare but potentially serious complication of pediatric cardiac operations. We report the case of a 4-month-old boy who underwent a Senning procedure for correction of D-transposition of the great vessels. A persistent postoperative chylothorax developed, necessitating continuous drainage, despite conservative treatment over 3 weeks. Thereafter, continuous somatostatin infusion for 14 days led to the reduction and finally cessation of chyle production. This treatment allowed early enteral feeding and avoided further surgical intervention.     

Leaflet''s free edge suspension for correction of aortic insufficiency associated with ventricular septal defect

Antibody in sera from 560 cattle of tuberculosis (TB)-infected and TB-free herds was investigated by competition and indirect enzyme-linked immunosorbent assays using bovine purified protein derivative tuberculin as the antigen. Antibody was detected in sera from both types of herd, with a widely overlapping range of titers. However, a "tail" of high-titered sera was observed for the distribution of data for only those cattle from TB-infected herds.     

Severe mitral insufficiency with ejection fraction below 40%: cardiac surgery is still indicated

Mitral insufficiency with an ejection fraction < 40% derives varying benefit from surgery according to its etiology: ischemic, degenerative or post-endocarditis. The impairment of the ejection fraction is also a determining factor. Analysis of a series of 26 cases confirms these findings.