出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/04/23 21:28:23」(JST)
| This article's citation style may be unclear. The references used may be made clearer with a different or consistent style of citation, footnoting, or external linking. (September 2009) |
| Beriberi | |
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| Classification and external resources | |
A sufferer – turn of the 20th century in southeast Asia |
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| ICD-10 | E51.1 |
| ICD-9 | 265.0 |
| DiseasesDB | 14107 |
| eMedicine | ped/229 med/221 |
| MeSH | D001602 |
Beriberi ( /bɛriˈbɛri/) is a nervous system ailment caused by a thiamine (vitamin B1) deficiency in the diet. Thiamine is involved in the breakdown of molecules such as glucose and is also found on the membranes of neurons. Symptoms of beriberi include severe lethargy and fatigue, together with complications affecting the cardiovascular, nervous, muscular, and gastrointestinal systems.
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The origin of the term is unclear, although several hypotheses have been suggested. One hypothesis is that it comes from a Sinhalese phrase meaning "weak, weak" or "I cannot, I cannot", the word being reduplicated for emphasis. [1] [2] [3] [4] Another hypothesis is that it is from the Arabic "bhur-bhari", meaning "sailor's asthma." [5] In 1630, a Dutch physician named Jacob Bonitus encountered the disease while working in Java. In the first known description of Beriberi, he wrote, "A certain very troublesome affliction, which attacks men, is called by the inhabitants Beriberi (which means sheep). I believe those, whom this same disease attacks, with their knees shaking and the legs raised up, walk like sheep. It is a kind of paralysis, or rather Tremor: for it penetrates the motion and sensation of the hands and feet indeed sometimes of the whole body." [6]
In Asia, where polished white rice (milled rice that has had its husk, bran, and germ removed) was the common staple food of the middle class, beriberi resulting from lack of vitamin B1 was endemic. In 1884, Takaki Kanehiro, a British-trained Japanese medical doctor of the Japanese Navy, observed that beriberi was endemic among low-ranking crew who often were provided nothing but rice, but not among crews of Western navies and officers who consumed a Western-style diet.
In 1883, Kanehiro learned of a very high incidence of beriberi among cadets on a training mission from Japan to Hawaii, via New Zealand and South America that lasted more than 9 months, resulting 376 cases of sickness and 25 deaths on a ship of 169 men. With the support of the Japanese Navy, he conducted an experiment in which another ship was deployed on the same route, except that its crew was fed a diet of meat, fish, barley, rice, and beans. At the end of the voyage, this crew had suffered only 14 cases of beriberi and no deaths. This convinced Kanehiro and the Japanese Navy that diet was the cause.[7]
In 1897, Dr. Christiaan Eijkman, a Dutch physician and pathologist, demonstrated that beriberi is caused by poor diet, and discovered that feeding unpolished rice (instead of the polished variety) to chickens helped to prevent beriberi. The following year, Sir Frederick Hopkins postulated that some foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, and salt—that were necessary for the functions of the human body.[8][9] In 1901, Gerrit Grijns (May 28, 1865 – November 11, 1944), a Dutch physician and assistant to Christiaan Eijkman in the Netherlands correctly interpreted the disease as a deficiency syndrome[10], and between 1910 and 1913, Dr. Edward Bright Vedder established that an extract of rice bran as a treatment for beriberi.[citation needed]
In 1929, Eijkman and Hopkins were awarded the Nobel Prize for Physiology or Medicine for this discovery.
Beriberi is rare in developed countries because most foods are now vitamin-enriched. Excluding the presence of arsenic in the environment (e.g. well water) one can get enough thiamine by eating a normal, healthy diet. Today, beriberi occurs mostly in patients who abuse alcohol. Drinking heavily can lead to poor nutrition, and excess alcohol makes it harder for the body to absorb and store thiamine.
Its symptoms include weight loss, emotional disturbances, impaired sensory perception (Wernicke's encephalopathy), weakness and pain in the limbs, and periods of irregular heart rate. Edema (swelling of bodily tissues) is common. It may increase the amount of lactic acid and pyruvic acid within the blood. In advanced cases, the disease may cause heart failure and death.
The main types of beriberi are:
Dry beriberi causes wasting and partial paralysis resulting from damaged peripheral nerves. It is also referred to as endemic neuritis. It is characterized by:
A selective impairment of the large proprioceptive sensory fibers without motor impairment can occur and present as a prominent sensory ataxia, which is a loss of balance and coordination due to loss of the proprioceptive inputs from the periphery and loss of position sense [11]
Wet beriberi affects the heart; it is sometimes fatal, as it causes a combination of heart failure and weakening of the capillary walls, which causes the peripheral tissues to become edematous. It is also characterized by:
This type of beriberi is commonly found in children in developing countries. Obvious signs and symptoms are crying, but not loudly and without tears. Untreated, it can prove fatal within 24 hours.
A physical examination may show signs of congestive heart failure, which include:
A neurological exam may show signs of:
Blood tests will measure the amount of thiamine in the blood, or the decrease in the activity of the thiamine-dependent enzyme transketolase.
The goal of treatment is to provide the thiamine the body is lacking. This is done with thiamine supplements which are given by injection or taken by mouth.
Other vitamins may also be recommended to help.
Subsequent blood tests will determine if the thiamine supplements are being effective.
Treatment for beriberi is with thiamine hydrochloride, either in tablet form or injection. A rapid and dramatic recovery within hours can be made when this is administered to patients, and their health can be improved within an hour of starting treatment. In emergency situations where concentrated thiamin supplements are unavailable, feeding the patient with a thiamin-rich diet (e.g. whole grain brown bread) will lead to recovery, though at a much slower rate.
Beriberi is caused by a lack of thiamine (vitamin B1). Thiamine occurs naturally in unrefined cereals and fresh foods, particularly whole grain bread, fresh meat, legumes, green vegetables, fruit, milk, etc. Beriberi is therefore common in people whose diet excludes these particular types of nutrition e.g. as a result of famine.
Beriberi may be found in people whose diet consists mainly of polished white rice, which is very low in thiamine because the thiamin-bearing husk has been removed. It can also be seen in chronic alcoholics (Wernicke-Korsakoff syndrome), Arsenic poisoning causes alterations in cellular metabolism resulting in blockage of thiamine use which results in thiamine deficiency without any dietary shortfall.[12] The mechanism of arsenic neuropathy may be similar to the neuropathy of thiamine deficiency [Sexton and Gowdy 1963], whereby arsenic inhibits the conversion of pyruvate to acetyl coenzyme A and thus blocks the Krebs cycle.
The disease was often found in Asian countries (especially in the 19th century and before), due to those countries' reliance on white rice as a staple food.
Thiamine deficiency causes neuropathy through neuron death due to its effects upon astrocytes. This causes alterations in their glutamate uptake, through changes in the levels of the astrocytic glutamate transporters EAAT1 and EAAT2 creating excitotoxicity. Other changes include those to the GABA transporter subtype GAT-3, GFAP, glutamine synthetase, the water channel protein Aquaporin 4. These create lactic acidosis, brain edema, oxidative stress, inflammation, and white matter impairment.[13]
A rare condition known as genetic beriberi is passed down through families. People with genetic beriberi lose the ability to absorb thiamine from foods. This can happen slowly over time and symptoms occur when the person is an adult. However, because doctors may not consider beriberi in non-alcoholics, this diagnosis is often missed.
Beriberi can occur in breast-fed infants when the mother's body is lacking in thiamine. The condition can also affect infants who are fed unusual formulas that don't have enough thiamine.
Getting dialysis and taking high doses of diuretics can raise the risk of beriberi. It is also occasionally diagnosed in patients having undergone roux-en-y gastric bypass or other enteric diversion weight-loss surgery.
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| リンク元 | 「ビタミンB1欠乏症」 |
| 関連記事 | 「deficiency」「B」「vitamin B1」 |