The structures of poly(p-hydroxybenzoic acid) (PHBA) whisker crystals and crystalline fine fibrils of copolymer prepared from p-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA), namely poly(HBA/HNA) (monomer molar ratio: 97/3), were investigated by transmission electron microscopy (TEM). As for a PHBA whisker, microfibril-like bright regions were recognized in the 210 dark-field image. In the high-resolution TEM image of another PHBA whisker, however, lattice fringes were continuous through the whisker, showing that the whisker is highly crystalline and almost perfect. On the other hand, in the high-resolution images of poly(HBA/HNA) fine fibrils, granular crystallites (20-40 nm in lateral dimension) were observed. The lattice fringes in the crystallites were not successfully indexed with the orthorhombic unit cells of the homopolymer crystal, suggesting the coexistence of another different structure as a minor component.

Crystallization↗

PubMedDate not supplied

Sandwich technique via right ventricle incision to repair postinfarction ventricular septal defect.

We describe two cases where postinfarction ventricular septal defect (VSD) was treated with a new technique. Application of direct ultrasonography to the right ventricular (RV) wall enables the surgeon to visualize the region and perform appropriate incision into the right ventricle and trabecula resection. The VSD is sealed with gelatin-resorcin-formal (GRF) glue between two patches, one placed on the left ventricular side and the other on the right ventricular side. RV incision provides easy bleeding control and the "sandwich technique" using two patches and GRF sealing provides geometric preservation of the left ventricular shape and prevents residual shunt.

Aged↗

PubMedDate not supplied

Skeletal muscle ventricles seeded with autogenous endothelium.

Skeletal muscle ventricles (SMVs) are muscular pumping chambers constructed from skeletal muscle. Previously, SMVs were connected to the systemic circulation with vascular conduits and used to assist the heart. In this study, SMVs were constructed from the latissimus dorsi muscle in eight dogs. The SMVs were seeded with autologous endothelial cells, but not connected to the circulation. Endothelial cells were harvested enzymatically from autogenous external jugular vein and grown in tissue culture. After 9 weeks, 6 electrically conditioned SMVs were seeded with endothelial cells by injecting 4-5 ml of culture medium containing 5-8 x 10(6) autogenous endothelial cells into each SMV lumen adjacent to the mandrel. Conditioning was stopped at the time of endothelial seeding. One week after seeding, electrical conditioning was resumed. Two weeks after seeding, the animals were killed and the SMVs excised. Histologic examination confirmed the presence of a confluent monolayer of cells covering 80-100% of the luminal surface in each seeded SMV. The endothelial nature of the cells lining the SMV lumen was established by fluorescent microscopy. Endothelial cells were pre labeled with the cellular marker PKH before seeding; the SMVs were also incubated with the endothelial marker dil-acetylated LDL. Endothelial cells also were identified by staining with fluorescently labeled antibodies to von Willebrand factor. Based upon these data, electrically conditioned SMVs can be seeded successfully with a near-complete, autologous endothelial monolayer. Additionally, this endothelial monolayer can be maintained on the luminal surface of a contracting SMV. In-circulation studies will determine whether endothelial cell seeding of SMVs can decrease or eliminate the incidence of thromboembolism.

Animals↗