Advances in cell transplantation therapy for diseased myocardium.

The overall objective of cell transplantation is to repopulate postinfarction scar with contractile cells, thus improving systolic function, and to prevent or to regress the remodeling process. Direct implantation of isolated myoblasts, cardiomyocytes, and bone-marrow-derived cells has shown prospect for improved cardiac performance in several animal models and patients suffering from heart failure. However, direct implantation of cultured cells can lead to major cell loss by leakage and cell death, inappropriate integration and proliferation, and cardiac arrhythmia. To resolve these problems an approach using 3-dimensional tissue-engineered cell constructs has been investigated. Cell engineering technology has enabled scaffold-free sheet development including generation of communication between cell graft and host tissue, creation of organized microvascular network, and relatively long-term survival after in vivo transplantation.

Xylanolytic activities of Streptomyces sp. 1--taxonomy, production, partial purification and utilization of agricultural wastes.

Twenty-four different strains of Streptomyces spp. isolated from Egyptian soil were tested for their ability to produce extracellular xylanases. Of all these isolates a Streptomyces sp. that had the highest potential for xylanolytic activity was chosen. From various morphological, physiological and antagonistic properties, this isolate was found to belong to Streptomyces lividans. Factors affecting xylanase production by this organism in a basal salt medium containing purified sugar-cane bagasse xylan as a sole carbon source were examined. A noticeable increase in enzyme activity was observed in the presence of peptone or soyabean meal. However, a slight increase was noticed with ammonium sulphate. Optimum production for xylanase was achieved after five days incubation on a rotary shaker (180 rpm) at 30 degrees C. The initial pH values were around neutrality. In addition, this organism has high potential for xylanolytic activity when grown on lignocellulosic wastes including corn cobs, wheat bran, peanut shells, sawdust, wheat straw and sugar-cane-bagasse. Partial purification of the enzyme in the culture supernatant was achieved by salting out at 50-80% ammonium sulphate saturation with a purification of 9.03-fold and 57.9% recovery.