Students, Premedical: Individuals enrolled in a preparatory course for medical school.Salivary Gland DiseasesSubmandibular Gland DiseasesTranscription Initiation, Genetic: The process that starts the transcription of an RNA molecule. It includes the assembly of the initiation complex and establishment of the start site.Salivary Gland Calculi: Calculi occurring in a salivary gland. Most salivary gland calculi occur in the submandibular gland, but can also occur in the parotid gland and in the sublingual and minor salivary glands.Salivary Duct Calculi: Presence of small calculi in the terminal salivary ducts (salivary sand), or stones (larger calculi) found in the larger ducts.Smiling: A facial expression which may denote feelings of pleasure, affection, amusement, etc.Submandibular Gland: One of two salivary glands in the neck, located in the space bound by the two bellies of the digastric muscle and the angle of the mandible. It discharges through the submandibular duct. The secretory units are predominantly serous although a few mucous alveoli, some with serous demilunes, occur. (Stedman, 25th ed)Aminolevulinic Acid: A compound produced from succinyl-CoA and GLYCINE as an intermediate in heme synthesis. It is used as a PHOTOCHEMOTHERAPY for actinic KERATOSIS.Sjogren's Syndrome: Chronic inflammatory and autoimmune disease in which the salivary and lacrimal glands undergo progressive destruction by lymphocytes and plasma cells resulting in decreased production of saliva and tears. The primary form, often called sicca syndrome, involves both KERATOCONJUNCTIVITIS SICCA and XEROSTOMIA. The secondary form includes, in addition, the presence of a connective tissue disease, usually rheumatoid arthritis.Sialography: Radiography of the SALIVARY GLANDS or ducts following injection of contrast medium.Human Coprophagia: A rare aberrant human behavior involving consumption of excrement.Mice, Inbred MRL lpr: A mouse substrain that is genetically predisposed to the development of systemic lupus erythematosus-like syndrome, which has been found to be clinically similar to the human disease. It has been determined that this mouse strain carries a mutation in the fas gene. Also, the MRL/lpr is a useful model to study behavioral and cognitive deficits found in autoimmune diseases and the efficacy of immunosuppressive agents.Parotitis: INFLAMMATION of the PAROTID GLAND.Salivary Glands, Minor: Accessory salivary glands located in the lip, cheek, tongue, floor of mouth, palate and intramaxillary.Autoimmune Diseases: Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides.Parotid Gland: The largest of the three pairs of SALIVARY GLANDS. They lie on the sides of the FACE immediately below and in front of the EAR.Retroperitoneal Fibrosis: A slowly progressive condition of unknown etiology, characterized by deposition of fibrous tissue in the retroperitoneal space compressing the ureters, great vessels, bile duct, and other structures. When associated with abdominal aortic aneurysm, it may be called chronic periaortitis or inflammatory perianeurysmal fibrosis.Salivary Gland Neoplasms: Tumors or cancer of the SALIVARY GLANDS.