I-P 2

Melena: Abnormally dark black, tarry feces containing blood (usually from gastrointestinal bleeding). Menarche: The first menstrual cycle. Meninges: Membranes surrounding the brain and spinal cord. Meningismus: Symptoms similar to meningitis (nuchal rigidity, photophobia, and headache) but not caused by meningitis. Mesial temporal lobe epilepsy: A common epilepsy syndrome manifested by seizures arising from the mesial temporal lobe of the brain, and is often associated with an anatomical change, described as hippocampal sclerosis. Mesocortical pathway: A neural pathway that connects the ventral tegmentum to the cortex, particularly the frontal lobes. It is one of the major dopamine pathways in the brain. Mesothelioma: A benign or malignant tumor affecting the lining of the chest or abdomen. Commonly caused by exposure to asbestos fibers. Metabolic acidosis: A condition in the blood and tissues that is a consequence of an accumulation of lactic acid resulting from tissue hypoxia and anaerobic metabolism. It may also be caused by a decrease in the concentration of alkaline compounds (typically bicarbonate). Metabolic syndrome: Constellation of cardiovascular risk factors related to hypertension, abdominal obesity, dyslipidemia, and insulin resistance diagnosed by the presence of at least three of the following criteria: increased waist circumference, elevated triglyceride concentrations, decreased high density lipoprotein (HDL) cholesterol or active treatment to raise HDL cholesterol, elevated blood pressure or active treatment with antihypertensive therapy, or elevated fasting glucose or active treatment for diabetes. Metastasis: Cancer that has spread from the original site of the tumor. Methemoglobinemia: A condition caused by elevated levels of methemoglobin in red blood cells, resulting in enhanced oxygen affinity in heme sites and reduced oxygen delivery to tissues; leads to hypoxia, cyanosis, shortness of breath, mental status changes, and dizziness. In severe cases, it can lead to seizures, coma, or death. Microalbuminuria: Urinary excretion of small but abnormal amounts of albumin. Confirmed spot urine albumin to creatinine ratio of 30 to 300 mg/g (3.4–34 mg/mmol creatinine) is consistent with microalbuminuria. Considered an early sign of chronic kidney disease. Microcytosis: A condition in which the erythrocytes are smaller than normal. Micrognathia: Abnormal smallness of the jaws. Micrographia: Small handwriting. Microsatellite instability (MSI): The condition of genetic hypermutability that results from impaired DNA mismatch repair (MMR). The presence of MSI represents phenotypic evidence that MMR is not functioning normally. Microvascular: Pertaining to the smaller vessels of the circulatory system such as capillaries, venules, and arterioles. Microvascular pulmonary emboli: An obstruction in the small blood vessels in the lung caused by material (eg, blood clot, fat, air, foreign body) that is carried through the circulation until it lodges in another small vessel. Micturition: Act of passing urine. Minimum inhibitory concentration: The lowest concentration of a drug that visually inhibits the growth of a microorganism. Minor malformation: Defect that has neither cosmetic nor functional significance to the patient. Mixed mood features: Symptoms of mania and depression occurring simultaneously or in close juxtaposition. Criteria are either met for a manic/hypomanic episode and there are also at least three symptoms of depression, or criteria are met for a depressive episode with at least three manic/hypomanic symptoms. Mobilization: A process by which medication(s) are used to promote the release of hematopoietic stem cells from the bone marrow to the peripheral blood for the purpose of collecting a sufficient amount of hematopoietic stem cells for a hematopoietic stem cell transplant. Moebius syndrome: Rare congenital neurological disorder which is characterized by facial paralysis and affects eye movement. Monoamine neurotransmitters: Serotonin, norepinephrine, dopamine. Monoparesis: Slight or incomplete paralysis affecting a single extremity or part of one. Monosodium urate: A crystallized form of uric acid that can deposit in joints leading to an inflammatory reaction and the signs and symptoms of gout. Morphology: Structure and form of a cell. Mucositis: Inflammatory, erosive, and/or ulcerative process inside the mouth, which is usually caused by radiation or chemotherapy. Multiparity: Condition of having given birth to multiple children. Muscularis mucosa: The thin layer of smooth muscle found in most parts of the gastrointestinal tract. Mydriasis: Pupil dilation. Myelin: A protein and phospholipid sheath that surrounds the axons of certain neurons. Myelinated nerves conduct impulses more rapidly than nonmyelinated nerves. Myeloablative preparative regimen: Chemotherapy regimens with or without radiation that cause irreversible cytopenias without hematopoietic stem cell support. Myelodysplastic syndrome: A type of cancer in which the bone marrow does not make enough healthy blood cells (white blood cells, red blood cells, and platelets) and there are abnormal cells in the blood and/or bone marrow. Myelopathy: A neurologic deficit related to the spinal cord. Myelosuppression: Reduction in white blood cells, red blood cells, and platelets. Myocardial infarction: The formation of an infarct, an area of tissue death, due to a local lack of oxygen. Myocardial cell death secondary to prolonged ischemia. Myocarditis: Inflammation of the heart muscle. Myoglobinuria: The presence of myoglobin in urine. Myonecrosis: Necrotic damage to muscle tissue. Myopathy: Any disease of the muscle causing weakness, pain, and tenderness. Myringotomy: A surgical incision made in the tympanic membrane to relieve pressure and drain fluid from the middle ear. Myxedema: Hypothyroidism characterized by a relatively hard edema of subcutaneous tissue, with increased content of proteoglycans in the fluid; characterized by somnolence, slow mentation, dryness and loss of hair, increased fluid in body cavities such as the pericardial sac, subnormal temperature, hoarseness, muscle weakness, and slow return of a muscle to the neutral position after a tendon jerk. Nail psoriasis: Characterized by pitting, onycholysis, hyperkeratosis, and an oil-drop sign.Nasal scotoma: An area of blindness in the nasal portion of peripheral vision. Nasolacrimal occlusion: The closing of the tear duct to decrease systemic absorption of a drug. Natriuresis: Excretion of sodium in the urine. Necrotizing enterocolitis: Medical condition seen in premature infants, where portions of the bowel undergo necrosis. Nelson syndrome: A condition characterized by the aggressive growth of a pituitary tumor and hyperpigmentation of the skin. Neoadjuvant therapy: Treatment given before the primary modality to downsize the tumor. Nephrolithiasis: A condition marked by the presence of renal calculi (stones) in the kidney or urinary system. Nephron: The working unit of the kidney that filters blood to remove fluid, toxins, and drugs. Each kidney contains approximately 1 million nephrons. Nephrostomy: An artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system (renal pelvis). Neuritic plaques: Extracellular deposits of amyloid beta with concentration markedly increased in the hippocampus, amygdala, and cerebral cortex. The plaque is thought to be formed through a cascade involving the formation of abnormally folded amyloid beta from amyloid precursor protein. Neuritis: Inflammation of a nerve. Neurofibrillary tangles: Aggregates of hyperphosphorylated tau protein which can disrupt cellular function and lead to cellular degeneration and death. Neuropathic pain: Pain resulting from a lesion or dysfunction of the nervous system. Neuropathy: An abnormal and usually degenerative state of the nervous system or nerves. Damage to the small and large nerves due to glycation end products, lack of blood and nutrients to the nerves, or chemical imbalances. Neurotransmitters: Chemicals in the brain that allow the passage of a message between neurons or nerve cells. Neutralizing antibodies: Antibodies that develop in response to a therapeutic agent that decrease the efficacy of the agent. Nidus: A place in which something is formed or deposited; often used to refer to the site in which bacteria have lodged and multiply. Nociception: Encoding and processing of noxious stimuli to the nervous system. Nociceptors: Receptors for pain caused by injury from physical stimuli (mechanical, electrical, or thermal) or chemical stimuli (toxins); located in the skin, muscles, or in the walls of the viscera. Nocturia: Urination that occurs during sleep, causing patients to awaken overnight. Nocturnal polysomnography: Electrophysiologic assessment of human sleep minimally composed of electroencephalogram, electrooculogram, and electromyogram that allows determination of sleep stage, breathing events, and muscle movements. Nodule: An abnormal small swelling or aggregation of cells in the body. When seen with rheumatoid arthritis, nodules are subcutaneous knobs over bony prominences or extensor surfaces. Non-rapid eye movement (REM) sleep: A state of usually dreamless sleep that occurs regularly during a normal period of sleep with intervening periods of REM sleep and that consists of four distinct substages and low levels of autonomic physiological activity. Nonbacterial thrombotic endocarditis: Endocarditis which consists of a sterile or noninfectious vegetation that has developed on the heart valve and may be visible on imaging tests.