MedicineNet.com
About Us | Privacy Policy | Site Map
November 8, 2009
MedicineNet home Picture Slideshows Diseases and conditions Symptoms and signs Procedures and tests Medications Health and Living Health news and views MedTerms medical dictionary
 MELAS Syndrome Main Article |  Glossary |  MELAS Syndrome Index 

MELAS Syndrome Glossary of Terms

The following are health and medical definitions of terms that appear in the MELAS Syndrome article.

Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
See the entire definition of Abnormal

Acidosis: Too much acid in the body, a distinctly abnormal condition resulting from the accumulation of acid or from the depletion of alkaline reserves. In acidosis, the pH of the blood is abnormally low. Acidosis is associated with diabetic ketoacidosis, lung disease, and severe kidney disease. The opposite of acidosis is alkalosis in which there is too high a pH due to excess base or insufficient acid in the body.

Atrophy: Wasting away or diminution. Muscle atrophy is wasting of muscle, decrease in muscle mass.
See the entire definition of Atrophy

Biopsy: The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.)
See the entire definition of Biopsy

Blood: The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.

Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
See the entire definition of Brain

Brain biopsy: Biopsy of the brain. Removal of a small piece of tissue from the brain for diagnostic purposes.
See the entire definition of Brain biopsy

Cell: The basic structural and functional unit in people and all living things. Each cell is a small container of chemicals and water wrapped in a membrane .
See the entire definition of Cell

Chromosome: A visible carrier of the genetic information.
See the entire definition of Chromosome

Chromosomes: The microscopically visible carriers of the genetic material. They are composed of deoxyribonucleic acid (DNA) and proteins and, under a microscope, look like little rods.
See the entire definition of Chromosomes

Clinical: 1. Having to do with the examination and treatment of patients. 2. Applicable to patients. A laboratory test may be of clinical value (of use to patients).
See the entire definition of Clinical

Condition: The term "condition" has a number of biomedical meanings including the following:

  1. An unhealthy state, such as in "this is a progressive condition."
  2. A state of fitness, such as "getting into condition."
  3. Something that is essential to the occurrence of something else; essentially a "precondition."
  4. As a verb: to cause a change in something so that a response that was previously associated with a certain stimulus becomes associated with another stimulus; to condition a person, as in behavioral conditioning.

Cytoplasm: All of the substance of a cell outside of the nucleus. The cytoplasm contains a number of different types organelles such as the mitochondria.
See the entire definition of Cytoplasm

Dementia : Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning.
See the entire definition of Dementia

Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV.
See the entire definition of Diagnosis back to top

Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

DNA: Deoxyribonucleic acid. One of two types of molecules that encode genetic information. (The other is RNA . In humans DNA is the genetic material; RNA is transcribed from it. In some other organisms, RNA is the genetic material and, in reverse fashion, the DNA is transcribed from it.)
See the entire definition of DNA

Dysfunction: Difficult function or abnormal function.
See the entire definition of Dysfunction

Epilepsy (seizure disorder): When nerve cells in the brain fire electrical impulses at a rate of up to four times higher than normal, this causes a sort of electrical storm in the brain, known as a seizure. A pattern of repeated seizures is referred to as epilepsy. Known causes include head injuries, brain tumors, lead poisoning, maldevelopment of the brain, genetic and infectious illnesses. But in fully half of cases, no cause can be found. Medication controls seizures for the majority of patients.

Eye: The organ of sight. The eye has a number of components. These components include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
See the entire definition of Eye

Female: The traditional definition of female was "an individual of the sex that bears young" or "that produces ova or eggs". However, things are not so simple today. Female can be defined by physical appearance, by chromosome constitution (see Female chromosome complement), or by gender identification. Female chromosome complement: The large majority of females have a 46, XX chromosome complement (46 chromosomes including two X chromosomes). A minority of females have other chromosome constitutions such as 45,X (45 chromosomes including only one X chromosome) and 47,XXX (47 chromosomes including three X chromosomes).

Genetic: Having to do with genes and genetic information.

Kearns-Sayre syndrome: A neuromuscular disorder characterized by three primary findings:

  • Progressive paralysis of certain eye muscles (chronic progressive external ophthalmoplegia, or CPEO);
  • Abnormal accumulation of colored (pigmented) material on the retina (atypical retinitis pigmentosa ), leading to chronic inflammation and progressive degeneration of the retina; and
  • Heart disease ( cardiomyopathy ) such as cardiac conduction defects and heart block .
Other findings in the syndrome may include muscle weakness, short stature, hearing loss, and the loss of ability to coordinate voluntary movements ( ataxia ) due to problems in the part of the brain called the cerebellum .
See the entire definition of Kearns-Sayre syndrome

Lactic acidosis: Acidosis (too much acid in the body) due to the buildup of lactic acid in the body. Lactic acidois occurs when cells make lactic acid (from glucose ) faster than it can be metabolized. The key signs of lactic acidosis include unusually deep and rapid breathing , vomiting, and abdominal pain .
See the entire definition of Lactic acidosis

Male: The traditional definition of male was "an individual of the sex that produces sperm" (or some such). However, things are not so simple today. Male can be defined by physical appearance, by chromosome constitution (see Male chromosome complement), or by gender identification.

MELAS syndrome : MELAS is the acronym for Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes.
See the entire definition of MELAS syndrome

Mitochondria: Normal structures responsible for energy production in cells. Mitochondria are located in the cytoplasm outside the nucleus of the cell. They consist of two sets of membranes, a smooth continuous outer coat and an inner membrane arranged in tubules or in folds that form plate-like double membranes (cristae).
See the entire definition of Mitochondria

Mitochondrial: Referring to mitochondria. The mitochondria are normal structures called organelles in cells. They are located in the cell's cytoplasm outside the nucleus.
See the entire definition of Mitochondrial

Mitochondrion: Singular of mitochondria. The mitochondria are normal structures called organelles in cells. They are located in the cell's cytoplasm outside the nucleus .
See the entire definition of Mitochondrion

Mother: (1) The female parent. (2) To produce offspring as a female. To attribute the maternity of. (3) A cell or other structure from which similar cells or structures are formed. Accordingly, such a cell might be referred to as the mother cell.(4) To provide maternal protection, guidance, and nurturing to children.
See the entire definition of Mother back to top

Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."

Muscle biopsy: A minor surgical procedure done under local anesthetic using a needle or a small incision to remove a small sample of muscle. The procedure may be done to confirm a clinical diagnosis, distinguish between nerve and muscle disorders, identify a metabolic defect of muscle, diagnose diseases of connective tissue and blood vessels, detect muscle inflammation, or rule out muscle disease. Afterwards, there may be minor discomfort and bruising at the biopsy site which usually takes a week to heal fully.
See the entire definition of Muscle biopsy

Myoclonus: A condition of abnormal contraction of muscles or portions of muscles.

Neuromuscular: Pertaining to both nerves and muscles, as in neuromuscular blockade by an anesthetic agent, the neuromuscular junction (the meeting place of a nerve and a muscle fiber), and neuromuscular transmission (the transfer of "information" from the nerve to the muscle).

Nucleus: 1) In cell biology, the structure that houses the chromosomes. 2) In neuroanatomy, a group of nerve cells.

Optic: Having to do with vision.

Paralysis: Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism.

Progressive: Increasing in scope or severity. Advancing. Going forward. In medicine, a disease that is progressive is going from bad to worse.
See the entire definition of Progressive

Proteins: Large molecules composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.
See the entire definition of Proteins

Syndrome: A set of signs and symptoms that tend to occur together and which reflect the presence of a particular disease or an increased chance of developing a particular disease.
See the entire definition of Syndrome back to top

 MELAS Syndrome Main Article |  Glossary |  MELAS Syndrome Index 




Suggested Reading by Our Doctors
MedicineNet Doctors
  • Stroke - Learn about strokes symtoms like sudden numbness or weakness in the face, arms, or legs, confusion, vision problems, problems with walking or coordination, or severe headache.
  • Dementia - Learn about the types of dementia, and what causes it, the symptoms, diagnosis, treatment and prevention of this progressive disease.
  • Seizure (Epilepsy) - Learn about epilepsy, or seizure disorder. Causes include head injury, trauma, prenatal injury, poisoning, medications, stroke, heart attacks, alcoholism, infection, and more. Symptoms, diagnosis, and treatment information is included in the information.

Latest Medical News



WebMD Daily

Get breaking medical news.


Are you Depressed? Take the Quiz

Your Guide to Symptoms & Signs: Pinpoint Your Pain



MELAS Syndrome

What is a stroke?

A stroke, or cerebrovascular accident (CVA), occurs when blood supply to part of the brain is disrupted, causing brain cells to die. When blood flow to the brain is impaired, oxygen and glucose cannot be delivered to the brain. Blood flow can be compromised by a variety of mechanisms.

Blockage of an artery

  • Narrowing of the small arteries within the brain can cause a so-called lacunar stroke, (lacune=empty space). Blockage of a single arteriole can affect a tiny area of brain causing that tissue to die (infarct).
  • Hardening of the arteries (atherosclerosis) leading to the brain. There are four major blood vessels that supply the brain with blood. The anterior circulation of the brain that controls most motor, activity, sensation, thought, speech, and emotion is supplied by the carotid arteries. The posterior circulation, which supplies the brainstem and the cerebellum, con...

Read the Stroke article »










Health categories:

Slideshows | Diseases & Conditions | Symptoms & Signs | Procedures & Tests | Medications | Health & Living | News & Views | Medical Dictionary

Popular health centers:

Allergies | Arthritis | Cancer | Diabetes | Digestion | Healthy Kids | Heart | Men's Health | Mental Health | Women's Health | More...

Publications:

ePublications (PDFs) | XML News via RSS | Audio Podcasts | Email Newsletters

MedicineNet.com:

About Us | Privacy Policy | Site Map | WebMD® | Medscape® | eMedicine® | eMedicineHealth® | RxList®

This website is certified by Health On the Net Foundation. Click to verify. This site complies to the HONcode standard for trustworthy health information:
verify here.

©1996-2009 MedicineNet, Inc. All rights reserved. Notices and Legal Disclaimer.
MedicineNet does not provide medical advice, diagnosis or treatment. See additional information.