WordNet

travel or traverse (a distance); "This car does 150 miles per hour"; "We did 6 miles on our hike every day"
the syllable naming the first (tonic) note of any major scale in solmization (同)doh, ut
proceed or get along; "How is she doing in her new job?"; "How are you making out in graduate school?"; "Hes come a long way" (同)fare, make_out, come, get along
create or design, often in a certain way; "Do my room in blue"; "I did this piece in wood to express my love for the forest" (同)make
carry on or function; "We could do with a little more help around here" (同)manage
get (something) done; "I did my job" (同)perform
treat with an agent; add (an agent) to; "The ray dosed the paint"
the quantity of an active agent (substance or radiation) taken in or absorbed at any one time (同)dosage
a measured portion of medicine taken at any one time (同)dosage
the smallest possible quantity (同)lower_limit
the point on a curve where the tangent changes from negative on the left to positive on the right
a British imperial capacity measure (liquid or dry) equal to 1/60th fluid dram or 0.059194 cubic centimeters
a United States liquid unit equal to 1/60 fluidram

PrepTutorEJDIC

《疑問文・否定文を作る》 / 《否定命令文を作る》 / 《助動詞とbe動詞のどちらも含まない文に用いて付加疑問を作る》 / 《強意語として》 / 《文》《助動詞とbe動詞のどちらも含まない文に用いて倒置文を作る》 / 《あいづちを打つ場合に》 / 《先行する動詞またはそれを含む述部の代用》 / 《so,nor,neitherで始まる簡略文で》 / …‘を'『する』,行う,果たす / 《通例have done,時にbe doneの形で》…‘を'『終える』,済ませる / …‘を'作る,作り出す / …‘を'『処理する』,整える,片付ける / 〈学課〉‘を'『勉強する』,専攻する / 〈利益・害など〉‘を'与える,もたらす / 〈人〉‘に'『役立つ』,用が足りる(serve) / …の速度で進む,距離を行く / …‘を'見物する / 〈劇〉‘を'上演する;…‘の'役を演じる / …の役目(仕事)をする / 《おもに英》…‘を'だます,かつぐ / 《話》…をへとへとにさせる / 『する』;活動する / 《通例have done,時にbe doneの形で》(…を)『終える』,済ます《+『with』+『名』》 / 〈事が〉『運ぶ』;〈人が〉暮らしていく,健康である / 〈物が〉(…に)『間に合う』,十分である;〈人が〉(…に)役に立つ,向く《+『for』+『名』》 / 《複数形で》すべきこと / 〈C〉《おもに英》大宴会,大パーティー / 〈C〉《英話》詐欺,ぺてん
ド(全音階の第1音)
(おもに飲み薬1回分の)『服用量』 / (痛いこと・いやなことの)1回分,一定量 / (人などが受ける放射線の)線量 / 性病 / (…を)…‘に'投薬する,服用させる《+『名』+『with』+『名』》
《通例単数形で》『最小限』,最小量 / (数学で)極小,最小値,極小値 / 《名詞の前にのみ用いて》『最小限の』,最小量の
ミニム(液量の最小単位) / 《英》二分音符(《米》half note)
死をもたらす,致死の;死をもたらす目的の

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/07/19 16:32:19」(JST)

wiki en

[Wiki en表示]

In toxicology, the lethal dose (LD) is an indication of the lethality of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. The lethal concentration is a lethal dose measurement used for gases or particulates. The LD may be based on the standard person concept, a theoretical individual that has perfectly "normal" characteristics, and thus not apply to all sub-populations.

Median lethal dose (LD₅₀)

The median lethal dose, LD₅₀ (abbreviation for "lethal dose, 50%"), LC₅₀ (lethal concentration, 50%) or LCt₅₀ (lethal concentration and time) of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration. LD₅₀ figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD₅₀ is indicative of increased toxicity.

The test was created by J.W. Trevan in 1927.^[1] The term "semilethal dose" is occasionally used with the same meaning, in particular in translations from non-English-language texts, but can also refer to a sublethal dose; because of this ambiguity, it is usually avoided. LD₅₀ is usually determined by tests on animals such as laboratory mice. In 2011 the US Food and Drug Administration approved alternative methods to LD₅₀ for testing the cosmetic drug Botox without animal tests.^[2]

LD values for humans are best estimated by extrapolating results from human cell cultures. One form of measuring LD is to use animals like mice or rats, converting to dosage per kilogram of biomass, and extrapolating to human norms. The degree of error from animal-extrapolated LD values is large. The biology of test animals differs in important aspects to that of humans. For instance, mouse tissue is approximately fifty times less responsive than human tissue to the venom of the Sydney funnel-web spider. The square-cube law also complicates the scaling relationships involved. Researchers are shifting away from animal-based LD measurements in some instances. The U.S. Food and Drug Administration has begun to approve more non-animal methods in response to animal welfare concerns.^[3]

The LD₅₀ is usually expressed as the mass of substance administered per unit mass of test subject, typically as milligrams of substance per kilogram of body mass, but stated as nanograms (suitable for botulinum), micrograms, milligrams, or grams (suitable for paracetamol) per kilogram. Stating it this way allows the relative toxicity of different substances to be compared, and normalizes for the variation in the size of the animals exposed, although toxicity does not always scale simply with body mass.

The choice of 50% lethality as a benchmark avoids the potential for ambiguity of making measurements in the extremes and reduces the amount of testing required. However, this also means that LD₅₀ is not the lethal dose for all subjects; some may be killed by much less, while others survive doses far higher than the LD₅₀. Measures such as "LD₁" and "LD₉₉" (dosage required to kill 1% or 99%, respectively, of the test population) are occasionally used for specific purposes.^[4]

Lethal dosage often varies depending on the method of administration; for instance, many substances are less toxic when administered orally than when intravenously administered. For this reason, LD₅₀ figures are often qualified with the mode of administration, e.g., "LD₅₀ i.v."

The related quantities LD₅₀/30 or LD₅₀/60 are used to refer to a dose that without treatment will be lethal to 50% of the population within (respectively) 30 or 60 days. These measures are used more commonly with radiation, as survival beyond 60 days usually results in recovery.

Median infective dose

The median infective dose (ID₅₀) is the number of organisms received by a person or test animal qualified by the route of administration (e.g., 1,200 org/man per oral). Because of the difficulties in counting actual organisms in a dose, infective doses may be expressed in terms of biological assay, such as the number of LD₅₀'s to some test animal. In biological warfare infective dosage is the number of infective doses per minute for a cubic meter (e.g., ICt₅₀ is 100 medium doses - min/m³).

Lowest lethal dose

The lowest lethal dose (LD_Lo) is the least amount of drug that can produce death in a given animal species under controlled conditions.^[5]^[6] The dosage is given per unit of bodyweight (typically stated in milligrams per kilogram) of a substance known to have resulted in fatality in a particular species. When quoting an LD_Lo, the particular species and method of administration (e.g. ingested, inhaled, intravenous) are typically stated.

Median lethal concentration

For gases and aerosols, lethal concentration (given in mg/m³ or ppm, parts per million) is the analogous concept, although this also depends on the duration of exposure, which has to be included in the definition. The term incipient lethal level is used to describe a LC₅₀ value that is independent of time.^[7]

A comparable measurement is LCt₅₀, which relates to lethal dosage from exposure, where C is concentration and t is time. It is often expressed in terms of mg-min/m^3. LCt₅₀ is the dose that will cause incapacitation rather than death. These measures are commonly used to indicate the comparative efficacy of chemical warfare agents, and dosages are typically qualified by rates of breathing (e.g., resting = 10 l/min) for inhalation, or degree of clothing for skin penetration. The concept of Ct was first proposed by Fritz Haber and is sometimes referred to as Haber's Law, which assumes that exposure to 1 minute of 100 mg/m³ is equivalent to 10 minutes of 10 mg/m³ (1 × 100 = 100, as does 10 × 10 = 100).^{[citation needed]}

Some chemicals, such as hydrogen cyanide, are rapidly detoxified by the human body, and do not follow Haber's Law. So, in these cases, the lethal concentration may be given simply as LC₅₀ and qualified by a duration of exposure (e.g., 10 minutes). The Material Safety Data Sheets for toxic substances frequently use this form of the term even if the substance does follow Haber's Law.^{[citation needed]}

Lowest lethal concentration

The LC_Lo is the lowest concentration of a chemical, given over a period of time, that results in the fatality of an individual animal. LC_Lo is typically for an acute (<24 hour) exposure.^[8]^[9] It is related to the LC₅₀, the median lethal concentration. The LC_Lo is used for gases and aerosolized material.^[10]

Limitations

As a measure of toxicity, lethal dose is somewhat unreliable and results may vary greatly between testing facilities due to factors such as the genetic characteristics of the sample population, animal species tested, environmental factors and mode of administration.^[11]

There can be wide variability between species as well; what is relatively safe for rats may very well be extremely toxic for humans (cf. paracetamol toxicity), and vice versa. For example, chocolate, comparatively harmless to humans, is known to be toxic to many animals. When used to test venom from venomous creatures, such as snakes, LD₅₀ results may be misleading due to the physiological differences between mice, rats, and humans. Many venomous snakes are specialized predators of mice, and their venom may be adapted specifically to incapacitate mice; and mongooses may be exceptionally resistant. While most mammals have a very similar physiology, LD₅₀ results may or may not have equal bearing upon every mammal species, including humans.

Animal rights concerns

Animal-rights and animal-welfare groups, such as Animal Rights International,^[12] have campaigned against LD₅₀ testing on animals in particular as, in the case of some substances, causing the animals to die slow, painful deaths. Several countries, including the UK, have taken steps to ban the oral LD₅₀, and the Organisation for Economic Co-operation and Development (OECD) abolished the requirement for the oral test in 2001.^[13]

References

^ What is an LD50 and LC50
^ "In U.S., Few Alternatives To Testing On Animals". Washington Post. 12 April 2008. Retrieved 2011-06-26.
^ "Vision and Roadmap for the 21st Century". Source: National Toxicology Program. Retrieved 2011-10-29.
^ REGISTRY OF TOXIC EFFECTS OF CHEMICAL SUBSTANCES (RTECS)
COMPREHENSIVE GUIDE TO THE RTECS
^ What is an LD50 and LC50
^ "Allergan Receives FDA Approval for First-of-Its-Kind, Fully in vitro, Cell-Based Assay for BOTOX® and BOTOX® Cosmetic (onabotulinumtoxinA)". Allergan Web site. 24 June 2011. Retrieved 2012-08-15.
^ Schultz, Eric (2013). Fish Physiology: Euryhaline Fishes, Volume 32. Academic Press. pp. 481–482. ISBN 978-0-12-396951-4.
^ Encyclopedia of Genetics, Genomics, Proteomics and Informatics. Springer. 2008. doi:10.1007/978-1-4020-6754-9_9257. ISBN 978-1-4020-6754-9.
^ http://www.utexas.edu/safety/ehs/msds/glossary/?page=l
^ http://www.ilpi.com/msds/ref/lclo.html
^ Ernest Hodgson (2004). A Textbook of Modern Toxicology. Wiley-Interscience (3rd ed.).^{[page needed]}
^ Thirty-Two Years of Measurable Change
^ Cutler, David (February 1, 2001). "Death of LD50". Trends in Pharmacological Sciences 22. doi:10.1016/S0165-6147(00)01627-8.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. D群レンサ球菌（Streptococcus bovis、Streptococcus equinus complex）による感染症の臨床症状、診断、および治療 clinical manifestations diagnosis and treatment of infections due to group d streptococci streptococcus bovis streptococcus equinus complex
2. Overview of rodenticide poisoning
3. ボツリヌス中毒 botulism
4. 急性鉄中毒 acute iron poisoning
5. 致死的骨格形成異常の出生前診断 prenatal diagnosis of the lethal skeletal dysplasias

English Journal

Chitosan-isoniazid conjugates: Synthesis, evaluation of tuberculostatic activity, biodegradability and toxicity.

Berezin AS1, Skorik YA2.
Carbohydrate polymers.Carbohydr Polym.2015 Aug 20;127:309-15. doi: 10.1016/j.carbpol.2015.03.060. Epub 2015 Mar 30.
Novel water-soluble chitosan-isoniazid conjugates were synthesized by two methods: (1) the carbodiimide method using isoniazid (INH) and N-(2-carboxyethyl)chitosan (CEC), and (2) the reaction between INH and N-(3-chloro-2-hydroxypropyl)chitosan (CHPC). The solubility of the conjugates under physiolo
PMID 25965488

Pattern of multiresistant to antimicrobials and heavy metal tolerance in bacteria isolated from sewage sludge samples from a composting process at a recycling plant in southern Brazil.

Heck K1, De Marco ÉG, Duarte MW, Salamoni SP, Van Der Sand S.
Environmental monitoring and assessment.Environ Monit Assess.2015 Jun;187(6):328. doi: 10.1007/s10661-015-4575-6. Epub 2015 May 7.
The composting process is a viable alternative for the recycling of household organic waste and sewage sludge generated during wastewater treatment. However, this technique can select microorganisms resistant to antimicrobials and heavy metals as a result of excess chemicals present in compost windr
PMID 25944755

The direct anti-MRSA effect of emodin via damaging cell membrane.

Liu M1, Peng W, Qin R, Yan Z, Cen Y, Zheng X, Pan X, Jiang W, Li B, Li X, Zhou H.
Applied microbiology and biotechnology.Appl Microbiol Biotechnol.2015 May 22. [Epub ahead of print]
Methicillin-resistant Staphylococcus aureus (MRSA) has become an important bacterium for nosocomial infection. Only a few antibiotics can be effective against MRSA. Therefore, searching for new drugs against MRSA is important. Herein, anti-MRSA activities of emodin and its mechanisms were investigat
PMID 25998658

Japanese Journal

チアクロプリドのチアゾリジン部位の改変が殺虫・神経遮断活性に及ぼす影響およびネオニコチノイドの鍵ファーマコフォア考察のための定量的構造活性相関研究

利部伸三,西村勁一郎,成瀬有二 [他],大野育也
日本農薬学会誌 33(1), 58-66, 2008-02-20
ネオニコチノイド系殺虫剤チアクロプリドのファーマコフォアであるシアノイミノチアゾリジン部位をイミダゾリジン,ピロリジン,あるいはオキサゾリジンのようなヘテロ環(以下中心環と呼ぶ)に変え,それらの6-chloro-3-pyridylmethylや5-chloro-3-thiazolylmethyl誘導体の,注射法によるワモンゴキブリに対する殺虫活性とゴキブリ神経軸索を用いた伝導遮断活性を測定した.試 …
NAID 110006614072

ネオニコチノイド系殺虫剤のファーマコフォアにかかわる研究(<特集>農薬活性分子の作用機構研究に関する最近の進歩)

利部伸三
日本農薬学会誌 33(1), 9-13, 2008-02-20
ネオニコチノイド系殺虫剤のファーマコフォアにかかわる3種の研究をおこない下記の結果を得た.(1)17種の2-nitroiminoimidazolidine部位の構造変異体の定量的構造活性相関研究から,ワモンゴキブリの中枢神経に対する神経遮断活性は,ニトロ基の酸素原子のマリケン電荷と分子のPowの双方に比例した.(2)3-フロオロプロピル基がイミダクロプリドのクロロニコチニル基を代替しうるかを検討し …
NAID 110006614062