Extracellular deposits of the amyloid beta protein
Amyloid plaques (also known as neuritic plaques, amyloid beta plaques or senile plaques) are extracellular deposits of amyloid beta (Aβ) protein that present mainly in the grey matter of the brain.[1][2][3][4]Degenerativeneuronal elements and an abundance of microglia and astrocytes can be associated with amyloid plaques. Some plaques occur in the brain as a result of aging, but large numbers of plaques and neurofibrillary tangles are characteristic features of Alzheimer's disease.[5]
The plaques are highly variable in shape and size; in tissue sections immunostained for Aβ, they comprise a log-normal size distribution curve, with an average plaque area of 400-450 square micrometers (μm2). The smallest plaques (less than 200 μm2), which often consist of diffuse deposits of Aβ,[4] are particularly numerous.[6] Plaques form when Aβ misfolds and aggregates into oligomers and longer polymers, the latter of which are characteristic of amyloid.[7]
History
In 1892, Paul Blocq and Gheorghe Marinescu first described the presence of plaques in grey matter.[8][9] They referred to the plaques as 'nodules of neuroglial sclerosis'. In 1898, Emil Redlich reported plaques in three patients, two of whom had clinically verified dementia.[10] Redlich used the term 'miliary sclerosis' to describe plaques because he thought they resembled millet seeds, and he was the first to refer to the lesions as 'plaques'.[4]
In the early 20th century, Oskar Fischer noted their similarity to actinomyces 'Drusen' (geode-like lesions), leading him to call the degenerative process 'drusige Nekrose'.[11]Alois Alzheimer is often credited with first linking plaques to dementia in a 1906 presentation (published in 1907),[12] but this short report focused mainly on neurofibrillary tangles, and plaques were only briefly mentioned.[4] Alzheimer's first substantive description of plaques appeared in 1911.[11] In contrast, Oskar Fischer published a series of comprehensive investigations of plaques and dementia in 1907, 1910 and 1912.[11] By 1911, Max Bielschowsky proposed the amyloid-nature of plaque deposits. This was later confirmed by Paul Divry, who showed that plaques that are stained with the dye Congo Red show the optical property of birefringence,[13] which is characteristic of amyloids in general.[14]
In 1911, Teofil Simchowicz introduced the term 'senile plaques' to denote their frequent presence in the brains of older individuals.[15][16][17] In 1968, a quantitative analysis confirmed the association of senile plaques with dementia.[18] The term 'neuritic plaques' was used in 1973 to designate plaques that include abnormal neuronal processes (neurites).[19] An advance in 1984 and 1985 was the identification of Aβ as the protein that forms the cores of plaques.[20] This discovery led to the generation of new tools to study plaques, particularly antibodies to Aβ, and presented a molecular target for the development of potential therapies for Alzheimer's disease.[4][21][22][23]
The generation of amyloid beta
Amyloid beta (Aβ) is a small protein, most often 40 or 42 amino acids in length, that is released from a longer parent protein called the Aβ-precursor protein (APP).[24] APP is produced by many types of cell in the body, but it is especially abundant in neurons. It is a single-pass transmembrane protein, passing once through cellular membranes.[25]
The Aβ segment of APP is partly within the membrane and partly outside of the membrane. To liberate Aβ, APP is sequentially cleaved by two enzymes: first, by beta secretase (or β-amyloid cleaving enzyme (BACE)) outside the membrane, and second, by gamma secretase (γ-secretase), an enzyme complex within the membrane.[25] The sequential actions of these secretases results in Aβ protein fragments that are released into the extracellular space.[26][25] In addition to Aβ peptides that are 40 or 42 amino acids long, several less abundant Aβ fragments also are generated.[27][28] Aβ can be chemically modified in various ways, and the length of the protein and chemical modifications can influence both its tendency to aggregate and its toxicity.[4]
Identification
Amyloid plaques are visible with the light microscope using a variety of staining techniques, including silver stains, Congo red, Thioflavin, cresyl violet, PAS-reaction, and luminescent conjugated oligothiophenes (LCOs).[29][4][30] These methods often stain different components of the plaques, and they vary in their sensitivity[4][31] Plaques may also be visualized immunohistochemically with antibodies directed against Aβ or other components of the lesions. Immunohistochemical stains are especially useful because they are both sensitive and specific for antigens that are associated with plaques.[32]
Composition
The Aβ deposits that comprise amyloid plaques are variable in size and appearance.[3][4] Under the light microscope, they range from small, wispy accumulations that are a few microns in diameter to much larger dense or diffuse masses. So-called 'classical plaques' consist of a compact Aβ-amyloid core that is surrounded by a corona of somewhat less densely packed Aβ.[4] Classical plaques also include abnormal, swollen neuronal processes (neurites) deriving from many different types of neurons, along with activated astrocytes and microglia.[3][4] Abnormal neurites and activated glial cells are not typical of most diffuse plaques, and it has been suggested that diffuse deposits are an early stage in the development of plaques.[33]
Anatomical distribution
Dietmar Thal and his colleagues have proposed a sequence of stages of plaque formation in the brains of Alzheimer patients[34][35] In Phase 1, plaques appear in the neocortex; in Phase 2, they appear in the allocortex, hippocampal formation and amygdala; in Phase 3, the basal ganglia and diencephalon are affected; in Phase 4, plaques appear in the midbrain and medulla oblongata; and in Phase 5, they appear in the pons and cerebellum. Thus, in end-stage Alzheimer's disease, plaques can be found in most parts of the brain. They are uncommon in the spinal cord.[4]
Formation and spread
The normal function of Aβ is not certain, but plaques arise when the protein misfolds and begins to accumulate in the brain by a process of molecular templating ('seeding').[36]Mathias Jucker and Lary Walker have likened this process to the formation and spread of prions in diseases known as spongiform encephalopathies or prion diseases.[36][37] According to the prion paradigm, certain proteins misfold into shapes that are rich in beta-sheetsecondary structure.[7][38]
Involvement in disease
Abundant Aβ plaques, along with neurofibrillary tangles consisting of aggregated tau protein, are the two lesions that are required for the neuropathological diagnosis of Alzheimer's disease.[22][39] Although the number of neurofibrillary tangles correlates more strongly with the degree of dementia than does the number of plaques, genetic and pathological findings indicate that Aβ plays a central role in the risk, onset, and progression of Alzheimer's disease.[21]
The diagnosis of Alzheimer's disease typically requires a microscopic analysis of plaques and tangles in brain tissue, usually at autopsy.[40] However, Aβ plaques (along with cerebral Aβ-amyloid angiopathy) can be detected in the brains of living subjects by preparing radiolabeled agents that bind selectively to Aβ deposits in the brain after being infused into the blood.[41] The ligands cross the blood–brain barrier and attach to aggregated Aβ, and their retention in the brain is assessed by positron emission tomography. In addition, the presence of plaques and tangles can be estimated by measuring the amounts of the Aβ and tau proteins in the cerebrospinal fluid.[42][43]
Occurrence
The probability of having plaques in the brain increases with advancing age.[44] From the age of 60 years (10%) to the age of 80 years (60%), the proportion of people with senile plaques increases linearly. Women are slightly more likely to have plaques than are men.[45][44] Both plaques and Alzheimer's disease also are more common in aging persons with trisomy-21 (Down syndrome).[1][46] This is thought to result from the excess production of Aβ because the APP gene is on chromosome 21, which exists as three copies in Down syndrome.[46]
Amyloid plaques naturally occur in the aging brains of nonhuman species ranging from birds to great apes.[4] In nonhuman primates, which are the closest biological relatives of humans, plaques have been found in all species examined thus far.[47]Neurofibrillary tangles are rare, however, and no nonhuman species has been shown to have dementia along with the complete neuropathology of Alzheimer's disease.[48]
Research
Both human samples and experimental models of Alzheimer's disease have been used to study the biochemical, cytological, and inflammatory characteristics of amyloid plaques.[4] Experimental studies have focused not only on delineating mechanisms by which plaques arise and proliferate, but also on discovering methods by which they can be detected (and potentially prevented/removed) in the living brain.[4] However, several aspects of amyloid biology are still under investigation. For example, recent evidence has suggested that amyloid plaque formation is linked to brain microvascular trauma.[49][50] Other research implicates chronicinflammation of the brain and immune dysfunction of the nervous system.[51][52]
The environmental, physiological or genetic risk factors for plaque formation in Alzheimer's disease are under preliminary research.[53][54]
^Purves, Dale; Augustine, George J.; Fitzpatrick, David; Hall, William C.; LaManita, Anthony-Samuel; White, Leonard E.; Mooney, Richard D.; Platt, Michael L. (2012). Neuroscience (5th ed.). Sunderland, MA: Sinauer Associates. p. 713. ISBN978-0-87893-695-3.
^Alzheimer, A (1907). "Uber einen eigenartige Erkranung der Hirnrinde". Allgemeine Zeitschrift für Psychiatrie und Psychisch-Gerichtlich Medizin. 64: 146–8.
^Divry P (1927). "Etude histo-chimique des plaques séniles". Journal Belge de Neurologie et de Psychiatrie. 9: 643–657.
^Buxbaum JN; Linke RP (2012). "A molecular history of the amyloidoses". Journal of Molecular Biology. 421 (2–3): 142–159. doi:10.1016/j.jmb.2012.01.024. PMID22321796.
^Simchowicz T.: Histologische Studien über die senile Demenz. in: Nissl F., Alzheimer A. (Hrsg.): Histologische und histopathologische Arbeiten über die Grosshirnrinde mit besonderer Berücksichtigung der pathologischen Anatomie der Geisteskrankheiten. Jena: G. Fischer, 1911, p. 267–444.
^Ohry A; Buda O (2015). "Teofil Simchowicz (1879-1957): the scientist who coined senile plaques in neuropathology". Romanian Journal of Morphology and Embryology. 56 (4): 1545–1548. PMID26743308.
^Blessed G; Tomlinson BE; Roth M (1968). "The association between quantitative measures of dementia and of senile change in the cerebral grey matter of elderly subjects". British Journal of Psychiatry. 114 (512): 797–811. doi:10.1192/bjp.114.512.797. PMID5662937. S2CID42670035.
^Wisniewski, Henryk M.; Terry, Robert D. (1973). "Chapter 1: Reexamination of the pathogenesis of the senile plaque". In Zimmerman, H.M. (ed.). Progress in Neuropathology, Volume 2. Grune and Stratton. pp. 1–26. ISBN978-0-808-90775-6.
^Selkoe, DJ (1999). "Chapter 19: Biology of β-amyloid precursor protein and the mechanism of Alzheimer disease". In Terry, RD; Katzman, R; Bick, KL; Sisodia, SS (eds.). Alzheimer Disease. Lippincott Williams and Wilkins. pp. 293–310. ISBN0-7817-1503-2.
^Lamy C, Duyckaerts C, Delaere P, et al. (1989). "Comparison of seven staining methods for senile plaques and neurofibrillary tangles in a prospective series of 15 elderly patients". Neuropathology and Applied Neurobiology. 15 (6): 563–78. doi:10.1111/j.1365-2990.1989.tb01255.x. PMID2482455. S2CID25220224.
^Klingstedt T; Nilsson KPR (2012). "Luminescent conjugated poly- and oligo-thiophenes: optical ligands for spectral assignment of a plethora of protein aggregates". Biochemical Society Transactions. 40 (4): 704–710. doi:10.1042/BST20120009. PMID22817720.
^Thal DR; Rüb O; Orantes M; Braak H (2002). "Phases of Abeta-deposition in the human brain and its relevance for the development of AD". Neurology. 58 (12): 1791–1800. doi:10.1212/wnl.58.12.1791. PMID12084879. S2CID41133337.
دوري الدرجة الأولى السعودي السلسلة دوري الدرجة الأولى السعودي الموسم 2016–17 البلد السعودية الفائز نادي الفيحاء صاعدون نادي الفيحاءنادي أحد هابطون نادي العدالةنادي الجيلنادي وج المباريات الملعوبة 240 الأهداف المسجلة 599 (2.5 لكل مباراة) هداف الدوري عبد الفتاح آدم(20 أهد
Menara Jeddah atau Jeddah Tower (Arab: برج جدة),[1] sebelumnya dikenal dengan nama Kingdom Tower (برج المملكة) dan Mile-High Tower (برج الميل) adalah sebuah bangunan pencakar langit yang dalam proses pembangunan di kota Jeddah, Arab Saudi. yang awal biaya pembangunannya sebesar SR4.6 miliar (US$1.23 miliar). Jika selesai pada tahun 2020 sesuai perencanaan, Menara Jeddah akan menjadi bangunan tertinggi di dunia maupun juga struktur bangunan pertama yang menc...
هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (نوفمبر 2019) دانتي روبرسون معلومات شخصية الميلاد سنة 1972 (العمر 50–51 سنة) ستانفرد، كاليفورنيا مواطنة الولايات المتحدة الحياة العملية المهنة طبال، ومن�...
Ця стаття є кандидатом на вилучення. Ознайомитися та долучитися до обговорення цієї номінації можна на сторінці Вікіпедія:Статті-кандидати на вилучення/28 листопада 2023. Доки воно триває, Ви можете працювати над покращенням цієї статті, але не прибирайте це повідомлення. �...
Kupferstich des Stosch’schen Steins von Johann Adam Schweickart aus dem Jahr 1756 Johann Adam Schweickart, auch Schweikard (* 19. Oktober 1722 in Nürnberg; † 14. Oktober 1787 ebenda), war ein deutscher Zeichner und Kupferstecher in Nürnberg. Inhaltsverzeichnis 1 Leben 2 Werke (Auswahl) 3 Literatur 4 Weblinks Leben Kupferstich des etruskischen Skarabäus mit Tydeus von Johann Adam Schweickart aus dem Jahr 1767 Er war der Sohn des Buchdruckers Wolfgang Schweikart, sein Taufpate war der da...
New Zealand political candidatesin the MMP era 1996 party lists by electorate 1999 party lists by electorate 2002 party lists by electorate 2005 party lists by electorate 2008 party lists by electorate 2011 party lists by electorate 2014 party lists by electorate 2017 party lists by electorate 2020 party lists by electorate 2023 party lists by electorate ...
For the Ultimate Disc team, see Connecticut Constitution (AUDL). This article uses bare URLs, which are uninformative and vulnerable to link rot. Please consider converting them to full citations to ensure the article remains verifiable and maintains a consistent citation style. Several templates and tools are available to assist in formatting, such as reFill (documentation) and Citation bot (documentation). (August 2022) (Learn how and when to remove this template message) Constitution of th...
Species of beetle that produces a toxic blistering agent This article is about the insect species. For the isolated chemical and its applications, see Cantharidin. For other uses of the term Spanish fly, see Spanish fly (disambiguation). Spanish fly Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Coleoptera Infraorder: Cucujiformia Family: Meloidae Genus: Lytta Species: L. vesicatoria Binomial name Lytta vesicatoria(Linnaeus, 1758) T...
Cricket in Sri LankaCountrySri LankaGoverning bodySri Lanka CricketNational team(s)Sri LankaFirst played1800National competitions National Super League 4-Day Tournament National Super League Limited Over Tournament Lankan Premier League Club competitions Premier Trophy Premier Limited Overs Tournament Premier Twenty20 Tournament International competitions Cricket World Cup ICC World Twenty20 ICC Champions Trophy Nidahas Trophy Warne–Muralidaran Trophy Sobers–Tissera Trophy ICC World Test ...
Removal of male sex organs Emasculate redirects here. For the song by Dorian Electra, see Emasculate (song). A painting of Zeus emasculating Cronus, c. 1501 Emasculation is the removal of both the penis and the scrotum (including the testicles), the external male sex organs. It differs from castration, which is the removal of the testicles only, although the terms are sometimes used interchangeably.[1] The potential medical consequences of emasculation are more extensive than th...
Transparent noodle made from starch Cellophane noodlesCooked cellophane noodlesAlternative namesGlass noodlesTypeNoodlesPlace of originChina[1]Region or stateEast Asia, Southeast AsiaAssociated cuisineChina, Indonesia, Japan, Korea, Malaysia, Philippines, Samoa, Thailand, Vietnam, Myanmar and TaiwanMain ingredientsStarch (from mung beans, yams, potatoes, cassava, canna, or batata), water Media: Cellophane noodles Regional nameChinese nameTraditional Chinese粉絲/粉條...
Scott Parker Parker bermasama Bournemouth pada 2021Informasi pribadiNama lengkap Scott Matthew Parker[1]Tanggal lahir 13 Oktober 1980 (umur 43)[2]Tempat lahir Lambeth, InggrisTinggi 175 cm (5 ft 9 in)[3]Posisi bermain GelandangKarier junior1990–1997 Charlton AthleticKarier senior*Tahun Tim Tampil (Gol)1997–2004 Charlton Athletic 128 (9)2000 → Norwich City (pinjaman) 6 (1)2004–2005 Chelsea 15 (1)2005–2007 Newcastle United 55 (4)2007–2011 ...
Badan Pengawas Pemilihan UmumGambaran UmumSingkatanBawasluDasar hukum pendirianUndang - Undang No 15 Tahun 2011SifatIndependenStrukturKetua/AnggotaRahmat BagjaAnggotaPuadiAnggotaTotok HariyonoAnggotaLolly SuhentiAnggotaHerwyn MalondaSekretaris JenderalIchsan FuadyKantor pusatJl. M.H. Thamrin No. 14 Jakarta PusatSitus webhttp://www.bawaslu.go.id/lbs Badan Pengawas Pemilihan Umum (disingkat Bawaslu) adalah lembaga penyelenggara Pemilu yang bertugas mengawasi penyelenggaraan Pemilu di selur...
SirJohn Spencer LoginBorn9 November 1809Stromness, Orkney, United KingdomDied18 October 1863Felixstowe, Suffolk, United KingdomNationalityBritishEducationUniversity of EdinburghOccupation(s)Surgeon, Royal NavyKnown forGuardianship of Maharajah Duleep Singh and Koh-i-NoorSpouseLena Campbell Sir John Spencer Login (9 November 1809 – 18 October 1863) was a Scottish surgeon in British India, best remembered as the guardian of Maharajah Duleep Singh and the Koh-i-Noor diamond following the ...
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Arcade's Greatest Hits: The Atari Collection 2 – news · newspapers · books · scholar · JSTOR (July 2013) (Learn how and when to remove this template message) 1998 video gameArcade's Greatest Hits:The Atari Collection 2Developer(s)Digital EclipsePublisher(s)Midw...
2005 single by Mötley Crüe For the Jack White song, see Entering Heaven Alive (album). If I Die TomorrowSingle by Mötley Crüefrom the album Red, White & Crüe Released23 May 2005 (UK) [1]GenreAlternative metal, hard rockLength3:46LabelUniversal RecordsSongwriter(s) Simple Plan Nikki Sixx Producer(s)Bob RockMötley Crüe singles chronology Treat Me Like the Dog I Am (2001) If I Die Tomorrow (2005) Sick Love Song (2005) If I Die Tomorrow is a song by the American heavy metal ban...
Type of robbery involving the theft of money/valuables being carried aboard trains This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Train robbery – news · newspapers · ...
Thom Burns RacingOwner(s)Thomas BurnsBob LazierBaseIndianapolis, Indiana, United StatesSeriesIndyCar SeriesCareerDebut1989Latest race2018Races competed5Drivers' Championships0Indy 500 victories0Race victories0Pole positions0 Thom Burns Racing (also known as Milligan/Burns Racing Team, Burns Racing Team, Burns Motor Sports, Burns Motorsports and Lazier-Burns Racing) was an American auto racing team that competed in the IndyCar Series from 1989 to 2018. The team was owned by Thomas Burns, an In...
River dolphins Periode Oligocene–Sekarang PreЄ Є O S D C P T J K Pg N Inioidea Baiji (†Lipotes vexillifer)TaksonomiKerajaanAnimaliaFilumChordataKelasMammaliaOrdoArtiodactylaSuperfamiliInioidea Muizon, 1988 Keluarga Iniidae Pontoporiidae lbs Lumba-lumba sungai adalah kategori nontaxonomic yang termasuk satu dari beberapa spesies baru yang punah dari lumba-lumba yang berada di sungai air tawar dan muara. Mereka menempati wilayah Asia dan Amerika Selatan. Semua anggota kelompok yang sebelu...