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Jacksonian seizure
A brief alteration in movement, sensation or nerve function caused by abnormal electrical activity in a localized area of the brain.
Seizures of this type typically cause no change in awareness or alertness. They are transient, fleeting, ephemeral.
Jacksonian seizures are extremely varied. They can for example involve head turning, eye movements, lip smacking, mouth movements, drooling, rhythmic muscle contractions in a part of the body, apparently purposeful movements, abnormal numbness, tingling, and a crawling sensation over the skin.
These seizures are named for the English neurologist John Hughlings Jackson who studied speech defects in brain disorders and confirmed the location of the speech center ("Broca's center") in the brain. He described what are today called Jacksonian seizures in 1863 and in 1875 found the areas in the brain that cause them. Jackson was among the great figures of 19th-century medicine.
Jadassohn-Lewandowski Syndrome
This syndrome is a form of what is called elephant nails from birth (pachyonychia congenita). The characteristic features include:
Abnormally thick curved nails (onychogryposis)
Thickening of the skin (hyperkeratosis) of the palms, soles, knees and elbows
White plaques (leukoplakia) in the mouth
Excess sweating (hyperhidrosis) of the hands and feet
Teeth are already erupted at birth (natal teeth)
Generation after generation in a family may show the syndrome. It is an autosomal dominant trait. The gene responsible for the syndrome is on chromosome 12 (in band 12q13) and a single copy of the gene (named PD1) is capable of causing the disease. The basic abnormality is a mutation (change) in a gene for keratin, a primary constituent of nails, hair, and skin. Alternate names for the syndrome include pachyonychia congenita of the Jadassohn-Lewandowski type and pachyonychia congenita with natal teeth and type 1 pachyonychia congenita. The syndrome is named for the professor of dermatology at the University of Bern in Switzerland, Josef Jadassohn (1860-1936), and his colleague, Felix Lewandowski (1879- 1921), who first described the syndrome in 1906. About their patient, a 15-year-old girl, they wrote: "The nail plates of all the fingers and toes are extremely thickened, and so hard that they cannot be cut with a scissors; the father has to trim them with a hammer and chisel."
Jail fever
Epidemic typhus, a severe acute (sudden-onset) infectious disease with prolonged high fever up to 40° C (104° F), intractable headache, and a pink-to-red raised rash. The cause is a microorganism called Rickettsia prowazekii. It is found worldwide and is transmitted by lice. The lice become infected on typhus patients and transmit illness to other people. The mortality increases with age and over half of untreated persons age 50 or more die. Also called European, classic, or louse-borne typhus.
Jakob’s disease
Better known as Creutzfeldt-Jakob disease (CJD), a dementing disease of the brain. It is believed due to an unconventional, transmissible agent (a prion). Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist. There is neither treatment nor cure for CJD. Other names for CJD include Creutzfeldt-Jakob syndrome, Jakob-Creutzfeldt disease, and spastic pseuodoparalysis.
Jakob-Creutzfeldt disease
A transmissible degenerative brain disorder technically termed spongiform encephalopathy. Eating "mad cow" meat or squirrel brain can lead to Jaqcob-Creuzfeldt-like disease. Jakob-Creutzfeldt disease, better known as Creutzfeldt-Jakob disease (CJD), a dementing disease of the brain. It is believed due to an unconventional, transmissible agent (a prion). Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist. There is neither treatment nor cure for CJD. Other names for CJD include Creutzfeldt-Jakob syndrome, Jakob’s disease, and spastic pseuodoparalysis.
JAMA
The Journal of the American Medical Association, better known as JAMA.
JAMA, which began publication in 1883, now bills itself as "the world's best-read medical journal". However one defines "best-read", JAMA clearly ranks as one of the two leading general medical journals published in the United States. The other is the New England Journal of Medicine.
JAMA is published by the American Medical Association (AMA) and reports American Medical Association policy, "as appropriate." However, according to JAMA, articles in it "do not reflect the official policy of the American Medical Association...." and JAMA has the objective of " maintaining editorial independence, objectivity, and responsibility."
The mission of JAMA is lofty: "To promote the science and art of medicine and the betterment of the public health."
JAMA carries original, generally well-documented, peer-reviewed medical articles on a diversity of clinical as well as laboratory topics. It has become a publication that is timely, credible and, as medical journals go, important.
Jamais vu
From the French, meaning "never seen". The illusion that the familiar does not seem familiar. The opposite of the feeling of "déjà vu."
Jaundice
Jaundice is a yellowish staining of the skin and white of the eyes (sclerae) with pigment of bile. Jaundice can be an indicator of liver or gallbladder disease or result from red blood cells rupturing (hemolysis).
Jaundice, congenital hemolytic
Known also as hereditary spherocytosis (HS), this is a genetic disorder of the red blood cell membrane clinically characterized by anemia, jaundice (yellowing) and splenomegaly (enlargement of the spleen).
In HS the red cells are smaller, rounder, and more fragile than normal. The red cells have a spherical rather than the biconcave-disk shape of the normal red cell. These rotund red cells (spherocytes) are osmotically fragile and less flexible than normal red cells and tend to get trapped in narrow blood passages, particularly in the spleen, and there they break up (hemolyze) leading to hemolytic anemia.
The clogging of the spleen with red cells almost invariably causes splenomegaly. The breakup of the red cells releases hemoglobin and the heme part gives rise to bilirubin, the pigment of jaundice. The excess bilirubin leads to the formation of gallstones, even in childhood, There is also often iron overload due to the excess destruction of iron-rich red cells.
Hereditary spherocytosis is most common in people of northern European ancestry. It often shows up in infancy or early childhood, causing anemia and jaundice. The bone marrow has to work extrahard to make more red cells. So, if in the course of an ordinary viral illness, the bone marrow stops making red cells, the anemia can quickly become profound. This is termed an aplastic crisis.
Laboratory studies show evidence not only of many spherocytes but also increased numbers of reticulocytes (young red blood cells), hyperbilirubinemia (increased blood levels of the jaundice pigment bilirubin due to the breakup of the red cells) and increased osmotic fragility of the red cells.
HS is due to a deficiency of a protein called ankyrin. Ankyrins are cell membrane proteins (thought to interconnect integral proteins with the spectrin-based membrane skeleton.) The ankyrin of red blood cells (erythrocytic ankyrin) is called ankyrin-R or ankyrin-1. It is represented by the symbol ANK1.
The HS gene, that for ANK1, has been mapped to chromosome 8 and, specifically, to chromosome band 8p11.2. HS is inherited as a dominant trait so, if a person with HS reproduces, their child (irrespective of whether it is a boy or girl) has a 50:50 chance to have HS.
The treatment of hereditary spherocytosis is to remove the spleen (splenectomy). Although the red cell defect persists, the breakup of the red cells (hemolysis) ceases. Splenectomy, however, is a hazard in young children. Young children without a spleen are at increased risk for overwhelming sepsis (bloodstream infection), particularly with the preumococcus bacteria. Splenectomy is therefore usually postponed if possible until the age of 3 years. Before having a splenectomy, anyone with HS should have the pneumococcal vaccine. Persons with HS (or another cause of brisk ongoing hemolysis) should take supplemental folic acid.
The prognosis (outlook) after splenectomy is for a normal life and a normal life expectancy.
HS is also known as severe atypical spherocytosis, spherocytosis type II, ankyrin deficiency, erythrocyte ankyrin deficiency, ankyrin-R deficiency, and ankyrin1 deficiency.
Jaundice, hemolytic
Jaundice caused by destruction of red blood cells. This can be an inborn condition (hereditary spherocytosis) or it may be caused by a blood transfusion from a different blood group, infection in the blood, or some types of poisoning.
See also spherocytosis, hereditary.
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