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B cell
A type of white blood cell and, specifically, a type of lymphocyte.
Many B cells mature into what are called plasma cells that produce antibodies (proteins) necessary to fight off infections while other B cells mature into memory B cells.
All of the plasma cells descended from a single B cell produce the same antibody which is directed against the antigen that stimulated it to mature. The same principle holds with memory B cells. Thus, all of the plasma cells and memory cells "remember" the stimulus that led to their formation.
The maturation of B cells takes place in birds in an organ called the bursa of Fabricus. B cells in mammals mature largely in the bone marrow.
The B cell, or B lymphocyte, is thus an immunologically important cell. It is not thymus-dependent, has a short lifespan, and is responsible for the production of immunoglobulins. It expresses immunoglobulins on its surface.
B variant GM2-gangliosidosis
This disorder known as Tay-Sachs disease (TSD) is concisely defined by OMIM (Online Mendelian Inheritance in Man) as “an autosomal recessive, progressive neurodegenerative disorder, which in the classic infantile form, is usually fatal by age 2 or 3 years, results from deficiency of the enzyme hexosaminidase A. “ “Autosomal” points to the gene for TSD residing on a nonsex (autosomal) chromosome (namely, chromosome15q23-q24). “Recessive” indicates a person with 2 copies of the gene has TSD whereas someone with 1 copy is a carrier in normal health. TSD worsens, with time, as the central nervous system progressively deteriorates. The “classic” (“textbook”) type of TSD has its insidious onset in infancy. The child with TSD usually develops normally for the first few months of life. An exaggerated startle reaction may first be noted. Head control is lost by 6-8 months of age. The infant cannot roll over or sit up. Spasticity and rigidity develop. Excessive drooling and convulsions become evident. Blindness and head enlargement set in by the second year. “Fatal by age 2 or 3 years” today would be modified to “fatal by age 5.” After age 2, total constant nursing care is needed. Death is due usually to cachexia (wasting away) or aspiration pneumonia initiated by food going down “the wrong way” into the lungs. TSD is due to deficiency of an enzyme (a protein needed to catalyze a specific chemical reaction within the body). Lack of the enzyme which results in failure to process a lipid (a fat) which accumulates and is deposited in the brain and other tissues, to their detriment. The enzyme is called hexosaminidase-A (hex-A) and the lipid that is deposited is called GM2-ganglioside. TSD is a model of a fatal metabolic disease that occurs primarily within a well- defined subpopulation. It is one of several genetic diseases found more often in persons of Jewish origin. (Other Jewish genetic diseases include Gaucher disease, Niemann-Pick disease, Bloom syndrome, and factor XI defiency). The frequency of TSD is much higher in Ashkenazi Jews (of European origin) than in other groups of Jews. (In the U.S., 95% of Jews are Ashkenazi and are at risk for TSD). TSD occurs more rarely, in non-Jews. Knowledge of the biochemical basis TSD has permitted screening programs for carrier detection and prenatal diagnosis of TSD. There are forms of TSD with somewhat more hex-A and hence later onset, termed juvenile TSD and adult TSH. Alternative names for TSD itself are amaurotic familial idiocy (outdated), hexosaminidase A deficiency, hex-A deficiency. TSD is named for the English physician Waren Tay (1843-1927) and the New York neurologist Bernard (Barney) Sachs (1858-1944). Tay in 1881 studied an infant with progressive neurological impairment and described “symmetrical changes in the yellow spot in each eye”, the “cherry-red spots” characteristic of TSD. Sachs saw a child In 1887 and the child’s sister in 1898 with the cherry-red spots and “arrested cerebral development” and in 1910 he demonstrated the presence of accumulated lipid in the brain and retina.
B. quintana
Also called Rochalimaea quintana), Bartonella quintana is an unusual rickettsial organism that can multiply within the gut of the body louse and then can be transmitted to humans. Transmission to people can occur by rubbing infected louse feces into abraded (scuffed) skin or into the conjunctivae (whites of the eyes).
Bartonella quintana (B. quintana) is the cause of trench fever, a disease that was first recognized in the trenches of World War I, when it is estimated to have affected more than a million people in Russia and on the fronts in Europe. Trench fever was again a major problem in the military in World War II and is seen endemically in Mexico, Africa, E. Europe, and elsewhere.
Urban trench fever occurs among the homeless people and people with alcoholism today. Outbreaks have been documented, for example, in Seattle, Baltimore (among injection-drug users), Marseilles (France) and Burundi.
The fever of trench fever is classically a 5-day fever ("quintan fever"). The onset of symptoms is sudden with high fever, severe headache, back pain and leg pain and a fleeting rash.
Recovery takes a month or more. Relapses are common.
It is now clear, that at least in its urban form among the homeless, trench fever can cause bloodstream infection (bacteremia) associated with nonspecific symptoms or no symptoms (New England Journal of Medicine 340: 184-189, 1999).
B. quintana also has been found responsible for a disease called bacillary angiomatosis in people infected with HIV and for infection of the heart and great vessels (endocarditis) with bloodstream infection (bacteremia). The full spectrum of disease caused by B. quintana is still unfolding.
b.i.d.
Seen on a prescription, b.i.d. means twice (two times) a day. It is an abbreviation for "bis in die" which in Latin means twice a day. The abbreviation b.i.d. is sometimes written without a period either in lower-case letters as "bid" or in capital letters as "BID". However it is written, it is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken. Other examples include:
q.d. (qd or QD) is once a day; q.d. stands for "quaque die" (which means, in Latin, once a day).
t.i.d. (or tid or TID) is three times a day ; t.i.d. stands for "ter in die" (in Latin, 3 times a day).
q.i.d. (or qid or QID) is four times a day; q.i.d. stands for "quater in die" (in Latin, 4 times a day).
q_h: If a medicine is to be taken every so-many hours, it is written "q_h"; the "q" standing for "quaque" and the "h" indicating the number of hours. So, for example, "2 caps q4h" means "Take 2 capsules every 4 hours."
Babinski phenomenon
A neurologic reflex that constitutes an important medical examination based upon what the big toe does when the sole of the foot is stroked. If the big toe goes up, that may mean trouble.
The Babinski reflex is obtained by stimulating the external portion (the outside) of the sole. The examiner begins the stimulation back at the heel and goes forward to the base of the toes. There are diverse ways to elicit the Babinski response. A useful way that requires no special equipment is with firm pressure from the examiner's thumb. Just stroke the sole firmly with the thumb from back to front along the outside edge.
Too vigorous stimulation may cause withdrawal of the foot or toe, which can be mistaken as a Babinski response.
The normal mature Babinski reflex is characterized by extension of the great toe and also by fanning of the other toes.
Most newborn babies are not neurologically mature they normally give a Babinski response. Upon stimulation of the sole, they extend the great toe. Many young infants do this, too, and it is perfectly normal. However, in time during infancy the Babinski response vanishes and, under normal circumstances, should never return.
A Babinski response in an older child or adult is abnormal. It is a sign of a problem in the central nervous system (CNS), most likely in a part of the CNS called the pyramidal tract.
Asymmetry of the Babinski response -- when it is present on one side but not the other -- is abnormal. It is a sign not merely of trouble but helps to lateralize that trouble (tell which side of the CNS is involved).
The Babinski reflex is known by a number of other names: the plantar response (because the sole is the plantar surface of the foot), the toe or big toe sign or phenomenon, and the Babinski sign. (It is wrong to say that the Babinski sign is positive or negative; it is present or absent).
Babinski, despite the Slavic sound of the name, was French: Joseph Francois Felix Babinski (1857-1932). His name will not be soon forgotten in medicine, thanks to the Babinski phenomenon.
Babinski reflex
An important neurologic test based, believe it or not, upon what the big toe does when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble.
The Babinski reflex is obtained by stimulating the external portion (the outside) of the sole. The examiner begins the stimulation back at the heel and goes forward to the base of the toes. There are diverse ways to elicit the Babinski response. A useful way that requires no special equipment is with firm pressure from the examiner's thumb. Just stroke the sole firmly with the thumb from back to front along the outside edge.
Care must be taken not to overdo it. Too vigorous stimulation may cause withdrawal of the foot or toe, which can be mistaken as a Babinski response.
The Babinski reflex is characterized by extension of the great toe and also by fanning of the other toes.
Most newborn babies are not neurologically mature and therefore show a Babinski response. Upon stimulation of the sole, they extend the great toe . Many young infants do this, too, and it is perfectly normal. However, in time during infancy the Babinski response vanishes and, under normal circumstances, should never return.
A Babinski response in an older child or adult is abnormal. It is a sign of a problem in the central nervous system (CNS), most likely in a part of the CNS called the pyramidal tract.
Asymmetry of the Babinski response -- when it is present on one side but not the other -- is abnormal. It is a sign not merely of trouble but helps to lateralize that trouble (tell which side of the CNS is involved).
The Babinski reflex is known by a number of other names: the plantar response (because the sole is the plantar surface of the foot), the toe or big toe sign or phenomenon, the Babinski phenomenon or sign. (It is wrong to say that the Babinski sign is positive or negative; it is present or absent).
Babinski, despite the Slavic sound of the name, was French: Joseph Francois Felix Babinski (1857-1932). He will never be forgotten in medicine, thanks to the reflex he found.
Babinski response
An important neurologic examination based upon what the big toe does when the sole of the foot is stroked. If the big toe goes up, that may mean trouble.
The Babinski response is obtained by stimulating the external portion (the outside) of the sole. The examiner begins the stimulation back at the heel and goes forward to the base of the toes. There are diverse ways to elicit the Babinski response. A useful way that requires no special equipment is with firm pressure from the examiner's thumb. Just stroke the sole firmly with the thumb from back to front along the outside edge.
Too vigorous stimulation may cause withdrawal of the foot or toe, which can be mistaken as a Babinski response.
The normal mature Babinski response also by fanning of the other toes.
Most newborn babies are not neurologically mature so they show a Babinski response. Upon stimulation of the sole, they extend the great toe. Many young infants do this, too, and it is perfectly normal. However, in time during infancy the Babinski response vanishes and, under normal circumstances, should never return.
A Babinski response in an older child or adult is abnormal. It is a sign of a problem in the central nervous system (CNS), most likely in a part of the CNS called the pyramidal tract.
Asymmetry of the Babinski response -- when it is present on one side but not the other -- is abnormal. It is a sign not merely of trouble but helps to lateralize that trouble (tell which side of the CNS is involved).
The Babinski response is known by a number of other names: the plantar response (because the sole is the plantar surface of the foot), the toe or big toe sign or phenomenon, and the Babinski reflex, rsign or phenomenon.
It is wrong to say that the Babinski response is positive or negative; it is present or absent.
Babinski, despite the Slavic sound of the name, was French: Joseph Francois Felix Babinski (1857-1932). His name will not soon be forgotten in medicine, thanks to the reflex he described.
Babinski sign
An important neurologic examination based upon what the big toe does when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble.
The Babinski sign is obtained by stimulating the external portion (the outside) of the sole. The examiner begins the stimulation back at the heel and goes forward to the base of the toes. There are diverse ways to elicit the Babinski response. A useful way that requires no special equipment is with firm pressure from the examiner's thumb. Just stroke the sole firmly with the thumb from back to front along the outside edge.
Too vigorous stimulation may cause withdrawal of the foot or toe, which can be mistaken as a Babinski sign.
The Babinski sign is manifest by the upturning of the big toe and also by fanning of the other toes.
Most newborn babies are not neurologically mature so they normally show a Babinski sign. Upon stimulation of the sole, they extend the great toe . Many young infants do this, too, and it is perfectly normal. However, in time during infancy the Babinski response vanishes and, under normal circumstances, should never return.
A Babinski sign in an older child or adult is abnormal. It is a sign of a problem in the central nervous system (CNS), most likely in a part of the CNS called the pyramidal tract.
Asymmetry of the Babinski sign -- when it is present on one side but not the other -- is abnormal. It is a sign not merely of trouble but helps to lateralize that trouble (tell which side of the CNS is involved).
The Babinski sign is known by a number of other names: the plantar response (because the sole is the plantar surface of the foot), the toe or big toe sign or phenomenon, and the Babinski reflex, response or phenomenon.
It is common but wrong to say that the Babinski sign is positive or negative; it is present or absent.
Babinski, despite the Slavic sound of the name, was French: Joseph Francois Felix Babinski (1857-1932). His name will never be forgotten in medicine.
Baby walker
A device that allows a baby to move about in a half-seated, half-upright position.
A "walker" may paradoxically delay a baby in development. The baby using a walker tends to be slow in reaching motor milestones such as sitting up, crawling, and walking and other milestones such as those involving memory, learning, and language skills.
The American Academy of Pediatrics advocates a "ban on the manufacture and sale of mobile infant walkers in the US." The AAP also stresses that parents should be made aware of the "lack of benefits" of baby walkers.
Baby, fetal alcohol syndrome
Alcohol is capable of causing birth defects. FAS (fetal alcohol syndrome) always involves brain damage. and impaired growth. FAS also always involves head and face abnormalities. No amount of alcohol has been proven safe during pregnancy. Women who are or may become pregnant are advised to avoid alcohol
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