To investigate the role of ET 1 in the pathogenesis of SU, a model was established by cold restraint stress(CRS) inducing rat ulcer, immunohistochemistry(IHC)ABC method and radioimmunoassay(RIA) methods were used to determine ET 1 content and to study the expression and location of ET 1 in stomach of normal and CRS rats,and to evaluate the ulcer index(UI). IHC showed that ET 1 was stained as brownish grains,localized in the cytoplasm of vascular endothelial cells, stomach smooth muscle cells, gastric epithelial and vascular smooth muscule cells around lamina muscularis mucosae in stomach. The proportion of ET 1 positive cells was significantly higher in 3h poststress gastric mucosa than in normal gastric mucosa in rats by IHC( P

Exosomes are cell-derived nanovesicles with diameters from 30 to 150 nm, released upon fusion of multivesicular bodies with the cell surface. They can transport nucleic acids, proteins, and lipids for intercellular communication and activate signaling pathways in target cells. In cancers, exosomes may participate in growth and metastasis of tumors by regulating the immune response, blocking the epithelial-mesenchymal transition, and promoting angiogenesis. They are also involved in the development of resistance to chemotherapeutic drugs. Exosomes in liquid biopsies can be used as non-invasive biomarkers for early detection and diagnosis of cancers. Because of their amphipathic structure, exosomes are natural drug delivery vehicles for cancer therapy.