Congenital or acquired abnormal outpouching of an intracranial blood vessel wall. Saccular (berry) aneurysms are the most common variant, and tend to form at arterial branch points near the base of the brain. Rupture results in SUBARACHNOID HEMORRHAGE or INTRACRANIAL HEMORRHAGES. Giant aneurysms (>2.5 cm in diameter) may compress adjacent structures, including the OCULOMOTOR NERVE (see also OCULOMOTOR NERVE DISEASES). (From Adams et al., Principles of Neurology, 6th ed, p841)

Epidural anesthesia administered via the sacral canal.

An epileptic syndrome characterized by the triad of infantile spasms, hypsarrhythmia, and arrest of psychomotor development at seizure onset. The majority present between 3-12 months of age, with spasms consisting of combinations of brief flexor or extensor movements of the head, trunk, and limbs. The condition is divided into two forms: cryptogenic (idiopathic) and symptomatic (secondary to a known disease process such as intrauterine infections; nervous system abnormalities; BRAIN DISEASES, METABOLIC, INBORN; prematurity; perinatal asphyxia; TUBEROUS SCLEROSIS; etc.). (From Menkes, Textbook of Child Neurology, 5th ed, pp744-8)

Viruses whose host is Salmonella. A frequently encountered Salmonella phage is BACTERIOPHAGE P22.

A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of seven named species: P. ursinus (chacma baboon), P. cynocephalus (yellow baboon), P. papio (western or Guinea baboon), P. anubis (anubis or olive baboon), P. hamadryas (hamadryas or sacred baboon), P. sphinx (mandrill), and P. leucophaeus (drill). Some authors have recognized a separate genus for the drill and mandrill: Mandrillus. The Papio genus is geographically distributed throughout east and west Africa, Arabia, Egypt, and the Sudan.

A slowly growing benign skin nodule consisting of poorly demarcated cellular fibrous tissue enclosing collapsed capillaries with scattered hemosiderin-pigmented and lipid macrophages. They are common, usually about 1 cm in diameter and occur in the dermis. Simple excision is always curative. (From Stedman, 25th ed; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1356)

Protease-resistant core of PrPSC, the abnormal isoform of prion proteins (PRIONS). PrP 27-30 is produced by limited proteolysis of the N-terminus of PrPSc.

A group of antigens that includes both the major and minor histocompatibility antigens. The former are genetically determined by the major histocompatibility complex. They determine tissue type for transplantation and cause allograft rejections. The latter are systems of allelic alloantigens that can cause weak transplant rejection.

Numerous almost invariably solitary polyps of the order Actiniaria.

A structurally and mechanistically diverse group of drugs that are not tricyclics or monoamine oxidase inhibitors. The most clinically important appear to act selectively on serotonergic systems, especially by inhibiting serotonin reuptake.