Production of glycosaminoglycans, collagen and elastic tissue by aortic medial explants

Efficacy of Annona squamosa on wound healing in streptozotocin-induced diabetic rats

Annona squamosa L. (Annonaceae), commonly known as custard apple, mainly used for its edible fruit, is also recognised with numerous medicinal properties. As there is no report on the efficacy of this plant for wound healing, we examined the efficacy of ethanolic extract of A. squamosa leaves on wound repair in streptozotocin-nicotinamide-induced diabetic rats. Open excision wounds were made on the back of rats. The drug at a dosage of 100 mg/kg body wt was reconstituted in 200 µl of phosphate buffered saline and applied topically once daily for the treated wounds. The control wounds were left untreated. Wound tissues formed on days 4, 8, 12 and 16 (post-wound) were used to estimate DNA, total protein, total collagen, hexosamine and uronic acid. Levels of lipid peroxides were also evaluated along with tensile strength and period of epithelialisation. A. squamosa L. increased cellular proliferation and collagen synthesis at the wound site as evidenced by increase in DNA, protein and total collagen. The treated wounds were observed to heal much faster as proved by enhanced rates of epithelialisation and wound contraction, which was also confirmed by histopathological examinations. The results strongly substantiate the beneficial effects of the topical application of A. squamosa L. in the acceleration of normal and diabetic wound healing.

Serum and growth factors regulate expression of a 43 kDa protein in smooth muscle cell cultures

Smooth muscle cells respond to injury and the presence of serum factors by modulating from a quiescent contractile cell to a motile synthetic phenotype. To evaluate the biochemical response to serum exposure, we examined the proteins synthesized and secreted in response to serum. The most prominent effect of serum was the rapid production of a protein with an apparent molecular weight of 43 kDa. Removal of serum from the culture environment led to a cessation of 43 kDa protein production. The effect of exogenous heparin on 43 kDa protein production was also evaluated. Neither the 43 kDa protein nor a previously described 38 kDa protein was induced by heparin. Further, heparin treatment did not counteract the effects of serum. These studies demonstrate that an early response of vascular smooth muscle cells to serum is the production of this previously undescribed protein and that other modifications of the culture conditions did not affect its synthesis.

Fibronectin inhibits morphological changes in cultures of vascular smooth muscle cells

In culture, vascular smooth muscle cells proliferate until they form a confluent sheet of cells. At that time the morphology of the culture becomes altered and the cells form multilayered regions that eventually develop into nodular aggregations. We now demonstrate that the transition from monolayer culture to nodular culture is influenced by the presence of components in conditioned media. The development of nodules is enhanced by conditioned medium made from nodular cultures but is either inhibited or unaffected by monolayer culture-conditioned medium. Examination of the two types of conditioned media using NaDodSO4- polyacrylamide gels reveals many similarities and one major difference. Nodular-conditioned medium contains a prominent 42 kilodalton polypeptide which is not present in monolayer-conditioned medium. Further, we demonstrate that although both nodular and monolayer cultures produce fibronectin the transition to nodular culture does not occur in the presence of exogeneously added plasma fibronectin.