WordNet

a decrease in size of an organ caused by disease or disuse (同)wasting, wasting away
undergo atrophy; "Muscles that are not used will atrophy"
any weakening or degeneration (especially through lack of use) (同)withering
of or relating to or consisting of muscle; "muscular contraction"
having or suggesting great physical power or force; "the muscular and passionate Fifth Symphony"

PrepTutorEJDIC

(栄養不良などによる)萎縮(いしゅく) / (一般的に)衰退,退化 / 萎縮する,衰退する / …'を'萎縮させる,衰退させる
『助肉の』,筋肉でできた / 筋肉による / 筋肉の発達した

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/03/26 13:58:42」(JST)

wiki en

Muscle atrophy is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass. Muscle atrophy results from a co-morbidity of several common diseases, including cancer, AIDS, congestive heart failure, COPD (chronic obstructive pulmonary disease), renal failure, and severe burns; patients who have "cachexia" in these disease settings have a poor prognosis. Moreover, starvation eventually leads to muscle atrophy. Disuse of the muscles will also lead to disuse atrophy while neurogenic atrophy is muscle atrophy that results from damage to the nerve that stimulates the muscle. Also, time in a less than 1 g environment without exercise will lead to atrophy.^{[clarification needed]}

Clinical settings of atrophy[edit]

There are many diseases and conditions which cause a decrease in muscle mass, known as atrophy, including: Dejerine Sottas syndrome (HSMN Type III), inactivity, as seen when a cast is put on a limb, or upon extended bedrest (which can occur during a prolonged illness); cachexia - which is a syndrome that is a co-morbidity of cancer and congestive heart failure; chronic obstructive pulmonary disease; burns, liver failure, etc. Other syndromes or conditions which can induce skeletal muscle atrophy are liver disease, and starvation.

Quality of life[edit]

Muscular atrophy decreases quality of life as the sufferer becomes unable to perform certain tasks or worsen the risks of accidents while performing those (like walking). Muscular atrophy increases the risks of falling in conditions such as IBM (inclusion body myositis). Muscular atrophy affects a major number of elderly.

Other muscles diseases, distinct from atrophy[edit]

During aging, there is a gradual decrease in the ability to maintain skeletal muscle function and mass. This condition is called "sarcopenia". The exact cause of sarcopenia is unknown, but it may be due to a combination of the gradual failure in the "satellite cells" which help to regenerate skeletal muscle fibers, and a decrease in sensitivity to or the availability of critical secreted growth factors which are necessary to maintain muscle mass and satellite cell survival.

In addition to the simple loss of muscle mass (atrophy), or the age-related decrease in muscle function (sarcopenia), there are other diseases which may be caused by structural defects in the muscle (muscular dystrophy), or by inflammatory reactions in the body directed against muscle (the myopathies).

Pathophysiology[edit]

Muscle mass is reduced as muscles atrophy with disuse.

Muscle atrophy occurs by a change in the normal balance between protein synthesis and protein degradation. During atrophy, there is a down-regulation of protein synthesis pathways, and an activation protein degradation.^[1] The particular protein degradation pathway which seems to be responsible for much of the muscle loss seen in a muscle undergoing atrophy is the ATP-dependent ubiquitin/proteasome pathway. In this system, particular proteins are targeted for destruction by the ligation of at least four copies of a small peptide called ubiquitin onto a substrate protein. When a substrate is thus "poly-ubiquitinated", it is targeted for destruction by the proteasome. Particular enzymes in the ubiquitin/proteasome pathway allow ubiquitination to be directed to some proteins but not others - specificity is gained by coupling targeted proteins to an "E3 ubiquitin ligase". Each E3 ubiquitin ligase binds to a particular set of substrates, causing their ubiquitination.

Potential treatment[edit]

Muscle atrophy can be opposed by the signaling pathways which induce muscle hypertrophy, or an increase in muscle size. Therefore one way in which exercise induces an increase in muscle mass is to downregulate the pathways which have the opposite effect.

One important rehabilitation tool for muscle atrophy includes the use of functional electrical stimulation to stimulate the muscles. This has seen a large amount of success in the rehabilitation of paraplegic patients.^[2]

Since the absence of muscle-building amino acids can contribute to muscle wasting (that which is torn down must be rebuilt with like material), amino acid therapy may be helpful for regenerating damaged or atrophied muscle tissue. The branched-chain amino acids or BCAAs (leucine, isoleucine, and valine) are critical to this process, in addition to lysine and other amino acids.

In severe cases of muscular atrophy, the use of an anabolic steroid such as methandrostenolone is administered to patients as a potential cure. A novel class of drugs, called SARM (selective androgen receptor modulators) are being investigating with promising results. They would have fewer side-effects, while still promoting muscle and bone tissue growth and regeneration. These claims are, however, yet to be confirmed in larger clinical trials.

Quantification[edit]

A CT scan can distinguish muscle tissue from other tissues and thereby estimate the amount of muscle tissue in the body.

Fast loss of muscle tissue (relative to normal turnover), can be approximated by the amount of urea in the urine. The equivalent nitrogen content (in gram) of urea (in mmol) can be estimated by the conversion factor 0.028 g/mmol.^[3] Furthermore, 1 gram of nitrogen is roughly equivalent to 6 gram of protein, and 1 gram of protein is roughly equivalent to 4 gram of muscle tissue. Subsequently, in situations such as muscle wasting, 1 mmol of excessive urea in the urine (as measured by urine volume in litres multiplied by urea concentration in mmol/l) roughly corresponds to a muscle loss of 0.67 gram.

Hibernation[edit]

Inactivity and starvation in mammals lead to atrophy of skeletal muscle, accompanied by a smaller number and size of the muscle cells as well as lower protein content.^[4] In humans, prolonged periods of immobilization, as in the cases of bed rest or astronauts flying in space, are known to result in muscle weakening and atrophy. Such consequences are also noted in small hibernating mammals like the golden-mantled ground squirrels and brown bats.^[5]

Bears are an exception to this rule; species in the family Ursidae are famous for their ability to survive unfavorable environmental conditions of low temperatures and limited nutrition availability during winter by means of hibernation. During that time, bears go through a series of physiological, morphological and behavioral changes.^[6] Their ability to maintain skeletal muscle number and size at time of disuse is of significant importance.

During hibernation, bears spend four to seven months of inactivity and anorexia without undergoing muscle atrophy and protein loss.^[5] There are a few known factors that contribute to the sustaining of muscle tissue. During the summer period, bears take advantage of the nutrition availability and accumulate muscle protein. The protein balance at time of dormancy is also maintained by lower levels of protein breakdown during the winter time.^[5] At times of immobility, muscle wasting in bears is also suppressed by a proteolytic inhibitor that is released in circulation.^[4] Another factor that contributes to the sustaining of muscle strength in hibernating bears is the occurrence of periodic voluntary contractions and involuntary contractions from shivering during torpor.^[7] The three to four daily episodes of muscle activity are responsible for the maintenance of muscle strength and responsiveness in bears during hibernation.^[7]

References[edit]

^ Sandri M. 2008. Signaling in Muscle Atrophy and Hypertrophy. Physiology 23: 160-170.
^ D.Zhang et al., Functional Electrical Stimulation in Rehabilitation Engineering: A survey, Nenyang technological University, Singapore
^ Section 1.9.2 (page 76) in: Jacki Bishop; Thomas, Briony (2007). Manual of Dietetic Practice. Wiley-Blackwell. ISBN 1-4051-3525-5.
^ ^a ^b Fuster G, Busquets S, Almendro V, López-Soriano FJ, Argilés JM (2007). "Antiproteolytic effects of plasma from hibernating bears: a new approach for muscle wasting therapy?". Clin Nutr 26 (5): 658–61. doi:10.1016/j.clnu.2007.07.003. PMID 17904252.
^ ^a ^b ^c Lohuis TD, Harlow HJ, Beck TD (2007). "Hibernating black bears (Ursus americanus) experience skeletal muscle protein balance during winter anorexia". Comp. Biochem. Physiol. B, Biochem. Mol. Biol. 147 (1): 20–8. doi:10.1016/j.cbpb.2006.12.020. PMID 17307375.
^ Carey HV, Andrews MT, Martin SL (2003). "Mammalian hibernation: cellular and molecular responses to depressed metabolism and low temperature". Physiol. Rev. 83 (4): 1153–81. doi:10.1152/physrev.00008.2003 (inactive 2008-06-24). PMID 14506303.
^ ^a ^b Harlow, H. J.; Lohuis, T.; Anderson-Sprecher, R. C.; Beck, T. D I. (2004). "Body Surface Temperature Of Hibernating Black Bears May Be Related To Periodic Muscle Activity". Journal of Mammalogy 85 (3): 414–419. doi:10.1644/1545-1542(2004)085<0414:BSTOHB>2.0.CO;2. ISSN 1545-1542.

External links[edit]

Muscular atrophy at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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1. 脊髄性筋萎縮症 spinal muscular atrophy
2. 筋萎縮性側索硬化症およびその他の運動ニューロン疾患の診断 diagnosis of amyotrophic lateral sclerosis and other forms of motor neuron disease
3. 筋力低下患者へのアプローチ approach to the patient with muscle weakness
4. デュシェンヌ型およびベッカー型筋ジストロフィーの臨床的特徴および診断 clinical features and diagnosis of duchenne and becker muscular dystrophy
5. 肢帯型筋ジストロフィー limb girdle muscular dystrophy

English Journal

Diversity in the androgen receptor CAG repeat has been shaped by a multistep mutational mechanism.

Santos D1, Pimenta J, Wong VC, Amorim A, Martins S.
American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics.Am J Med Genet B Neuropsychiatr Genet.2014 Oct;165(7):581-6. doi: 10.1002/ajmg.b.32261. Epub 2014 Jul 31.
The androgen receptor (AR) gene encodes a type of nuclear receptor that functions as a steroid-hormone activated transcription factor. In its coding region, AR includes a CAG repeat, which has been intensely studied due to the inverse correlation between repeat size and AR transcriptional activity.
PMID 25078541

Ret finger protein mediates Pax7-induced ubiquitination of MyoD in skeletal muscle atrophy.

Joung H1, Eom GH2, Choe N3, Lee HM4, Ko JH3, Kwon DH1, Nam YS1, Min H1, Shin S3, Kook J1, Cho YK5, Kim JC6, Seo SB7, Baik YH8, Nam KI9, Kook H10.
Cellular signalling.Cell Signal.2014 Oct;26(10):2240-8. doi: 10.1016/j.cellsig.2014.07.006. Epub 2014 Jul 12.
Skeletal muscle atrophy results from the net loss of muscular proteins and organelles and is caused by pathologic conditions such as nerve injury, immobilization, cancer, and other metabolic diseases. Recently, ubiquitination-mediated degradation of skeletal-muscle-specific transcription factors was
PMID 25025573

Stem cell-derived motor neurons from spinal and bulbar muscular atrophy patients.

Grunseich C1, Zukosky K2, Kats IR3, Ghosh L4, Harmison GG5, Bott LC6, Rinaldi C7, Chen KL8, Chen G9, Boehm M10, Fischbeck KH11.
Neurobiology of disease.Neurobiol Dis.2014 Oct;70:12-20. doi: 10.1016/j.nbd.2014.05.038. Epub 2014 Jun 9.
Spinal and bulbar muscular atrophy (SBMA, Kennedy's disease) is a motor neuron disease caused by polyglutamine repeat expansion in the androgen receptor. Although degeneration occurs in the spinal cord and muscle, the exact mechanism is not clear. Induced pluripotent stem cells from spinal and bulba
PMID 24925468

Japanese Journal

Problems with Daily Living and Performing Home Exercise in Japanese Home-Care Patients with Parkinson's Disease

Nakae Hideyuki,Tsushima Hitoshi
弘前医学 65(1), 55-64, 2014-04-15
… Conclusion: To prevent a decrease in activity due to disuse muscular atrophy, it is important to establish more eff ective home exercises for home-care PD patients so that they can do these exercises on a regular basis. …
NAID 120005429842

脊髄性筋萎縮症Ⅰ型児に対するコミュニケーション支援の1経験

佐々木千穂,境信哉,星有理香 [他]
保健科学研究誌 (11), 81-90, 2014-03-31
NAID 40020096306

MRIを用いた女性腰部疾患例における大腰筋特性

佐藤成登志,地神裕史,島田雄司,山本智章,Sato Naritoshi,Jigami Hirohumi,Shimada Yuuzi,Yamamoto Noriaki
新潟医療福祉学会誌 13(2), 2-7, 2014-03
… However, whether the cross sectional area of psoas major muscle was affected by low back pain, or the dysfunction of muscular atrophy of the psoas major muscle was the cause of back pain were not included in this study.世界の全人口の７０～８０％は一生に一度は腰痛を経験しており、この内85％は明らかな原因がなく、手術適応のない非特異的腰痛である。 …
NAID 120005442199

Related Pictures

★リンクテーブル★

リンク元	「筋萎縮」「amyotrophic」「筋萎縮症」
拡張検索	「distal spinal muscular atrophy」「progressive muscular atrophy」「spinal progressive muscular atrophy」「spinal muscular atrophy」
関連記事	「muscular」「atrophy」

「筋萎縮」

Muscle atrophy
	Classification and external resources
	; Prisoner of war exhibiting muscle loss as a result of malnutrition
ICD-10	M62.5
ICD-9	728.2
DiseasesDB	29472
MedlinePlus	003188
MeSH	D009133

　　[★]

英: muscle atrophy, muscular atrophy

	神経原性	筋原性
	下位運動ニューロン障害	ミオパチー
筋萎縮	遠位筋中心	近位筋中心
線維束性収縮	＋	－
原因疾患例	筋萎縮性側索硬化症	筋ジストロフィー
	Charcot-Marie-Tooth病	多発筋炎
	多発神経炎	内分泌ミオパチー

例外	近位筋が主に冒される	遠位筋が主に冒される
	Kugelberg-Welander病	筋強直性ジストロフィー
	Kennedy-Alter-Sung症候群	遠位型筋ジストロフィー
	Werdnig-Hoffmann病

「amyotrophic」

　　[★]

adj.

筋萎縮性の

ex.

amyotrophic lateral sclerosis, ALS, 筋萎縮性側索硬化症

関: amyotrophy、muscle atrophy、muscular atrophy

「筋萎縮症」

　　[★]

英: muscular atrophy、muscle atrophy、amyotrophy
関: 筋萎縮

「distal spinal muscular atrophy」

　　[★]

遠位型脊髄性筋萎縮症、遠位型脊髄性筋萎縮

関: bulbospinal neuronopathy、Kennedy syndrome、progressive muscular atrophy、spinal muscular atrophy

「progressive muscular atrophy」

　　[★] 進行性筋萎縮症、進行性筋萎縮

関: bulbospinal neuronopathy、distal spinal muscular atrophy、Kennedy syndrome、spinal muscular atrophy

「spinal progressive muscular atrophy」

　　[★] 脊髄性進行性筋萎縮症

「spinal muscular atrophy」

　　[★] 脊髄性筋萎縮症 SMA

「muscular」

　　[★]

adj.

筋肉の、筋の

関: muscle、muscularis、musculus、myo

「atrophy」

　　[★]

n.

萎縮

[1] Sandri M. 2008. Signaling in Muscle Atrophy and Hypertrophy. Physiology 23: 160-170.

[2] D.Zhang et al., Functional Electrical Stimulation in Rehabilitation Engineering: A survey, Nenyang technological University, Singapore

[3] Section 1.9.2 (page 76) in: Jacki Bishop; Thomas, Briony (2007). Manual of Dietetic Practice. Wiley-Blackwell. ISBN 1-4051-3525-5.

[pmid17904252-4] Fuster G, Busquets S, Almendro V, López-Soriano FJ, Argilés JM (2007). "Antiproteolytic effects of plasma from hibernating bears: a new approach for muscle wasting therapy?". Clin Nutr 26 (5): 658–61. doi:10.1016/j.clnu.2007.07.003. PMID 17904252.

[pmid17307375-5] Lohuis TD, Harlow HJ, Beck TD (2007). "Hibernating black bears (Ursus americanus) experience skeletal muscle protein balance during winter anorexia". Comp. Biochem. Physiol. B, Biochem. Mol. Biol. 147 (1): 20–8. doi:10.1016/j.cbpb.2006.12.020. PMID 17307375.

[pmid14506303-6] Carey HV, Andrews MT, Martin SL (2003). "Mammalian hibernation: cellular and molecular responses to depressed metabolism and low temperature". Physiol. Rev. 83 (4): 1153–81. doi:10.1152/physrev.00008.2003 (inactive 2008-06-24). PMID 14506303.

[Harlow-7] Harlow, H. J.; Lohuis, T.; Anderson-Sprecher, R. C.; Beck, T. D I. (2004). "Body Surface Temperature Of Hibernating Black Bears May Be Related To Periodic Muscle Activity". Journal of Mammalogy 85 (3): 414–419. doi:10.1644/1545-1542(2004)085<0414:BSTOHB>2.0.CO;2. ISSN 1545-1542.

匿名

検索

案内

案内

muscular atrophy