A synthetic noncalcemic, nonphosphatemic vitamin D analogue. Paricalcitol binds to the vitamin D receptor and has been shown to reduce parathyroid hormone (PTH) levels. This agent also increases the expression of PTEN ('Phosphatase and Tensin homolog deleted on chromosome Ten'), a tumor-suppressor gene, in leukemic cells and cyclin-dependent kinase inhibitors, resulting in tumor cell apoptosis and tumor cell differentiation into normal phenotypes. or Surgery to cut the parts of the vagus nerve that cause gastric acid to be made in the stomach. It is done to treat stomach ulcers or other conditions in which the stomach makes too much acid.