Tetrodotoxin

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Tetrodotoxin poisoning
)
Tetrodotoxin
Names
IUPAC name
(4R,4aR,5R,6S,7S,8S,8aR,10S,12S)-2-azaniumylidene-4,6,8,12-tetrahydroxy-6-(hydroxymethyl)-2,3,4,4a,5,6,7,8-octahydro-1H-8a,10-methano-5,7-(epoxymethanooxy)quinazolin-10-olate
Other names
anhydrotetrodotoxin, 4-epitetrodotoxin, tetrodonic acid, TTX
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.022.236 Edit this at Wikidata
IUPHAR/BPS
KEGG
UNII
  • InChI=1S/C11H17N3O8/c12-8-13-6(17)2-4-9(19,1-15)5-3(16)10(2,14-8)7(18)11(20,21-4)22-5/h2-7,15-20H,1H2,(H3,12,13,14)/t2-,3-,4-,5+,6-,7+,9+,10-,11+/m1/s1 ☒N
    Key: CFMYXEVWODSLAX-QOZOJKKESA-N ☒N
  • InChI=1/C11H17N3O8/c12-8-13-6(17)2-4-9(19,1-15)5-3(16)10(2,14-8)7(18)11(20,21-4)22-5/h2-7,15-20H,1H2,(H3,12,13,14)/t2-,3-,4-,5+,6-,7+,9+,10-,11+/m1/s1
    Key: CFMYXEVWODSLAX-QOZOJKKEBM
  • O1[C@@H]4[C@@](O)([C@@H]3O[C@@]1(O)[C@@H](O)[C@]2(N\C(N/[C@H](O)[C@H]23)=N)[C@@H]4O)CO
  • zwitterion: O1[C@@H]4[C@@](O)([C@@H]3O[C@@]1([O-])[C@@H](O)[C@]2(N\C(N/[C@H](O)[C@H]23)=[NH2+])[C@@H]4O)CO
Properties
C11H17N3O8
Molar mass 319.270 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Tetrodotoxin (TTX) is a potent

symbiotic bacteria like Pseudoalteromonas, Pseudomonas, and Vibrio as well as other species found in symbiotic relationships with animals and plants.[1][2]

Although it produces thousands of intoxications annually and several deaths,[3] it has shown efficacy for the treatment of cancer-related pain in phase II and III clinical trials.[4]

Tetrodotoxin is a

voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from contracting in response to nervous stimulation.[5]

Its mechanism of action‍— selective blocking of the sodium channel‍— was shown definitively in 1964 by Toshio Narahashi and John W. Moore at Duke University, using the sucrose gap voltage clamp technique.[6]

Sources in nature

Apart from their bacterial species of most likely ultimate biosynthetic origin (see below), tetrodotoxin has been isolated from widely differing animal species, including:[1]

Tarichatoxin was shown to be identical to TTX in 1964 by Mosher et al.,[12][13] and the identity of maculotoxin and TTX was reported in Science in 1978,[14] and the synonymity of these two toxins is supported in modern reports (e.g., at Pubchem[15] and in modern toxicology textbooks[16]) though historic monographs questioning this continue in reprint.[17]

The toxin is variously used by

ribbon worms).[18] Even though the toxin acts as a defense mechanism, some predators such as the common garter snake have developed insensitivity to TTX, which allows them to prey upon toxic newts.[19]

The association of TTX with consumed, infecting, or symbiotic bacterial populations within the animal species from which it is isolated is relatively clear;[1] presence of TTX-producing bacteria within an animal's microbiome is determined by culture methods, the presence of the toxin by chemical analysis, and the association of the bacteria with TTX production by toxicity assay of media in which suspected bacteria are grown.[2] As Lago et al. note, "there is good evidence that uptake of bacteria producing TTX is an important element of TTX toxicity in marine animals that present this toxin."[2] TTX-producing bacteria include Actinomyces, Aeromonas, Alteromonas, Bacillus, Pseudomonas, and Vibrio species;[2] in the following animals, specific bacterial species have been implicated:[a]

In the following table, open nomenclature terms "sp.", "spp.", "cf." are used; the non-italcized designation after a species name is the strain.
Association of animals with TTX-producing bacteria
Animal Bacteria Ref
Takifugu obscurus, obscure pufferfish
  • Aeromonas sp. Ne-1
  • Bacillus sp. W-3
 [2][5]
Nassarius semiplicatus, a gastropod
  • Vibrio spp., including V. alginolyticus, V. cf. shilonii, and unassigned ones
  • Marinomonas sp.
  • Tenacibaculum cf. aestuarii
 [1]
Hapalochlaena maculosa, the Southern blue-ringed octopus
  • Alteromonas spp.
  • Bacillus spp.
  • Pseudomonas spp.
  • Vibrio spp.
 [1][2][5][20]
Astropecten polyacanthus, a starfish Vibrio alginolyticus [2][5]
Takifugu vermicularis, a pufferfish
  • Vibrio spp., including V. alginolyticus
 [1][2][5][21]
Four species of Chaetognatha (arrow worms)
  • V. alginolyticus
 [22]
Species of Nemertea (ribbon worms) Vibrio spp. [1][23]

The association of bacterial species with the production of the toxin is unequivocal – Lago and coworkers state, "[e]ndocellular symbiotic bacteria have been proposed as a possible source of eukaryotic TTX by means of an exogenous pathway",

Takifugu niphobles puffers fed on TTX-containing diets saw TTX in the livers of the fishes increase to toxic levels.[1] Hence, as bacterial species that produce TTX are broadly present in aquatic sediments, a strong case is made for ingestion of TTX and/or TTX-producing bacteria, with accumulation and possible subsequent colonization and production.[1] Nevertheless, without clear biosynthetic pathways (not yet found in animals, but shown for bacteria),[25] it remains uncertain whether it is simply via bacteria that each animal accumulates TTX; the question remains as to whether the quantities can be sufficiently explained by ingestion, ingestion plus colonization, or some other mechanism.[1][2][5]

Biochemistry

Tetrodotoxin binds to what is known as site 1 of the fast voltage-gated sodium channel.[26] Site 1 is located at the extracellular pore opening of the ion channel. Any molecule bound to this site will block sodium ions from going into the nerve cell through this channel (which is ultimately necessary for nerve conduction). Saxitoxin, neosaxitoxin, and several of the conotoxins also bind the same site.[27]

The use of this toxin as a biochemical probe has elucidated two distinct types of voltage-gated sodium channels (VGSCs) present in mammals: tetrodotoxin-sensitive voltage-gated sodium channels (TTX-s Na+ channels) and tetrodotoxin-resistant voltage-gated sodium channels (TTX-r Na+ channels). Tetrodotoxin inhibits TTX-s Na+ channels at concentrations of around 1–10 nM,

cardiac
tissue, while nerve cells containing TTX-s Na+ channels dominate the rest of the body.

TTX and its analogs have historically been important agents for use as chemical tool compounds, for use in channel characterization and in fundamental studies of channel function.

neural activity within a cell culture
.

Biosynthesis

The biosynthetic route to TTX is only partially understood. It is long known that the molecule is related to saxitoxin, and as of 2011 it is believed that there are separate routes for aquatic (bacterial) and terrestrial (newt) TTX.[32] In 2020, new intermediates found in newts suggest that the synthesis starts with geranyl guanidine in the amphibian; these intermediates were not found in aquatic TTX-containing animals, supporting the separate-route theory.[33] In 2021, the first genome of a TTX-producing bacterium was produced. This "Bacillus sp. 1839" was identified as Cytobacillus gottheilii using its rRNA sequence. The researcher responsible for this study has not yet identified a coherent pathway but hopes to do so in the future.[34]

Resistance

Animals that accumulate TTX as a defense mechanism as well as their predators must evolve to be resistant to the effects of TTX. Mutations in the VGSC genes, especially the genes for Nav 1.4 (skeletal muscle VGSC, "TTX-s"[35]), are found in many such animals.[36] These mutations have independently arisen several times, even multiple times in different populations of the same species as seen in the garter snake. They consist of different amino acid substitutions in similar positions, a weak example of convergent evolution caused by how TTX binds to the unmutated VGSC.[36]

Another path to TTX resistance is toxin-binding proteins that hold onto TTX tightly enough to prevent it reaching the vulnerable VGSCs. Various proteins that bind TTX have been found in pufferfish, crabs, and gastropods. There are also proteins that bind saxitoxin (STX), a toxin with a similar mode of action.[36]

Chemical synthesis

In 1964, a team of scientists led by

C–H bond activation. Since then, methods have rapidly advanced, with several new strategies for the synthesis of tetrodotoxin having been developed.[45][46]

Poisoning

Toxicity

TTX is extremely toxic. The

LD50) for mice as 334 μg per kg.[47] For comparison, the oral LD50 of potassium cyanide for mice is 8,500 μg per kg,[48] demonstrating that even orally, TTX is more poisonous than cyanide. TTX is even more dangerous if administered intravenously; the amount needed to reach a lethal dose by injection is 8 μg per kg in mice.[49]

The toxin can enter the body of a victim by ingestion, injection, or inhalation, or through abraded skin.[50]

Poisoning occurring as a consequence of consumption of fish from the order

diaphragm and corresponding death due to respiratory failure.[51] Toxicity varies between species and at different seasons and geographic localities, and the flesh of many pufferfish may not be dangerously toxic.[5]

The mechanism of toxicity is through the blockage of fast voltage-gated sodium channels, which are required for the normal transmission of signals between the body and brain.[52] As a result, TTX causes loss of sensation, and paralysis of voluntary muscles including the diaphragm and intercostal muscles, stopping breathing.[53]

History

A Chinese pharmacopoeia, 1930.

The therapeutic uses of puffer fish (

Pen-T’so Kang Mu (Index Herbacea or The Great Herbal by Li Shih-Chen, 1596) some types of the fish Ho-Tun (the current Chinese name for tetraodon) were also recognized as both toxic yet, at the right dose, useful as part of a tonic. Increased toxicity in Ho-Tun was noted in fish caught at sea (rather than river) after the month of March. It was recognized that the most poisonous parts were the liver and eggs, but that toxicity could be reduced by soaking the eggs.[30] (Tetrodotoxin is slightly water-soluble, and soluble at 1 mg/ml in slightly acidic solutions.)[54]

The German physician Engelbert Kaempfer, in his "A History of Japan" (translated and published in English in 1727), described how well known the toxic effects of the fish were, to the extent that it would be used for suicide and that the Emperor specifically decreed that soldiers were not permitted to eat it.[55] There is also evidence from other sources that knowledge of such toxicity was widespread throughout southeast Asia and India.[30]

The first recorded cases of TTX poisoning affecting Westerners are from the logs of Captain James Cook from 7 September 1774.[51] On that date Cook recorded his crew eating some local tropic fish (pufferfish), then feeding the remains to the pigs kept on board. The crew experienced numbness and shortness of breath, while the pigs were all found dead the next morning. In hindsight, it is clear that the crew survived a mild dose of tetrodotoxin, while the pigs ate the pufferfish body parts that contain most of the toxin, thus being fatally poisoned.

The toxin was first isolated and named in 1909 by Japanese scientist Dr. Yoshizumi Tahara.[2][56][51] It was one of the agents studied by Japan's Unit 731, which evaluated biological weapons on human subjects in the 1930s.[57]

Symptoms and treatment

The diagnosis of pufferfish poisoning is based on the observed symptomatology and recent dietary history.[58]

Symptoms typically develop within 30 minutes of ingestion, but may be delayed by up to four hours; however, if the dose is fatal, symptoms are usually present within 17 minutes of ingestion.

irregular heartbeats may occur. The victim, although completely paralysed, may be conscious and in some cases completely understandable until shortly before death, which generally occurs within 4 to 6 hours (range ~20 minutes to ~8 hours). However, some victims enter a coma.[53][59]

If the patient survives 24 hours, recovery without any aftereffects will usually occur over a few days.[58]

Therapy is supportive and based on symptoms, with aggressive early airway management.

anticholinesterase agents "have been proposed as a treatment option but have not been tested adequately".[59]

No

USAMRIID that was effective, in the one study, for reducing toxin lethality in tests on mice.[60]

Worldwide distribution of toxicity

Poisonings from tetrodotoxin have been almost exclusively associated with the consumption of pufferfish from waters of the Indo-Pacific Ocean regions, primarily because equally toxic pufferfishes from other regions are much less commonly eaten. Several reported cases of poisonings, including fatalities, nonetheless involved pufferfish from the Atlantic Ocean,

Taricha granulosa on a dare.[61]

In 2009, a major scare in the Auckland Region of New Zealand was sparked after several dogs died eating Pleurobranchaea maculata (grey side-gilled seaslug) on beaches.[62] Children and pet owners were asked to avoid beaches, and recreational fishing was also interrupted for a time. After exhaustive analysis, it was found that the sea slugs must have ingested tetrodotoxin.[63]

Statistical factors

Statistics from the Tokyo Bureau of Social Welfare and Public Health indicate 20–44 incidents of fugu poisoning per year between 1996 and 2006 in the entire country, leading to 34–64 hospitalizations and 0–6 deaths per year, for an average fatality rate of 6.8%.[64] Of the 23 incidents recorded within Tokyo between 1993 and 2006, only one took place in a restaurant, while the others all involved fishermen eating their catch.[64] From 2006 through 2009 in Japan there were 119 incidents involving 183 people but only seven people died.[65]

Only a few cases have been reported in the United States, and outbreaks in countries outside the Indo-Pacific area are rare. In Haiti, tetrodotoxin was thought to have been used in voodoo preparations, in so-called zombie poisons. Subsequent careful analysis has however repeatedly called early studies into question on technical grounds, and failed to identify the toxin in any preparation.[66][67][68] Discussion of the matter has therefore all but disappeared from the primary literature since the early 1990s. Kao and Yasumoto concluded in the first of their papers in 1986 that "the widely circulated claim in the lay press to the effect that tetrodotoxin is the causal agent in the initial zombification process is without factual foundation."[66]: 748 

Genetic background is not a factor in susceptibility to tetrodotoxin poisoning. This toxicosis may be avoided by not consuming animal species known to contain tetrodotoxin, principally pufferfish; other tetrodotoxic species are not usually consumed by humans.

Fugu as a food

Poisoning from tetrodotoxin is of particular public health concern in Japan, where

viscera to reduce the danger of poisoning.[69]
There is potential for misidentification and mislabelling, particularly of prepared, frozen fish products.

Food analysis

The mouse bioassay developed for

trimethylsilyl derivatives by gas chromatography/mass spectrometry.[citation needed
]

Detection in body fluids

Tetrodotoxin may be quantified in serum, whole blood or urine to confirm a diagnosis of poisoning in hospitalized patients or to assist in the forensic investigation of a case of fatal overdosage. Most analytical techniques involve mass spectrometric detection following gas or liquid chromatographic separation.[70]

Modern therapeutic research

Tetrodotoxin has been investigated as a possible treatment for cancer-associated pain. Early clinical trials demonstrate significant pain relief in some patients.[71][72]

It has also been studied in relation to migraine headaches. Mutations in one particular TTX-sensitive Na+ channel are associated with some migraine headaches,[73] although it is unclear as to whether this has any therapeutic relevance for most people with migraine.[74]

Tetrodotoxin has been used clinically to relieve negative affects associated with

heroin withdrawal.[75]

Regulation

In the U.S., tetrodotoxin appears on the

Department of Health and Human Services,[76] and scientists must register with HHS to use tetrodotoxin in their research. However, investigators possessing less than 500 mg are exempt from regulation.[77]

Popular culture

Tetrodotoxin serves as a plot device for characters to fake death, as in the films

Columbo (season 7) In The Apothecary Diaries light novel, as well as the respective manga[81][82] and anime[83][84]
adaptations, fugu toxin is encountered across multiple mystery arcs.

Based on the presumption that tetrodotoxin is not always fatal, but at near-lethal doses can leave a person extremely unwell with the person remaining conscious,

ethnobotanist Wade Davis[85] in his 1985 book and Wes Craven's 1988 film, both titled The Serpent and the Rainbow. James Ellroy includes "blowfish toxin" as an ingredient in Haitian Vodou preparations to produce zombieism and poisoning deaths in his dark, disturbing, violent novel Blood's a Rover. But this theory has been questioned by the scientific community since the 1990s based on analytical chemistry-based tests of multiple preparations and review of earlier reports (see above).[66][67][68]

See also

References

  1. ^ For a more comprehensive list of TTX-producing bacterial species associated with animals from which the toxin has been isolated or toxicity observed, and for a thorough discussion of the research literature regarding bacterial origins (and the remaining contrary perspectives, e.g., in newts), as well as for a thorough speculative discussion regarding biosynthesis, see[1]
  1. ^
    PMID 21543051. Archived from the original
    (PDF) on 2016-03-05. Retrieved 2016-02-29.
  2. ^
    PMID 26492253
    .
  3. S2CID 204144112
    .
  4. PMID 37233510
    .
  5. ^
    PMID 24566728
    .
  6. PMID 14155438
    .
  7. ^ Sigma-Aldrich Tetrodotoxin (T8024) – Product Information Sheet.
  8. PMID 1949060
    .
  9. PMID 24963791
    .
  10. PMID 15581685
    .
  11. PMID 22164212
    .
  12. PMID 4929140
    .
  13. PMID 14148429
    .
  14. PMID 619451
    . Maculotoxin, a potent neurotoxin isolated from the posterior salivary glands of the blue-ringed octopus. Hapalochlaena maculosa, has now been identified as tetrodotoxin. This is the first reported case in which tetrodotoxin has been found to occur in a venom.
  15. ^ "Tetrodotoxin". PubChem. National Center for Biotechnology Information (NCBI).
  16. ISBN 978-1466503434
    .
  17. ISBN 978-0323155601
    .
  18. PMID 9535741
    .
  19. PMID 28567972
    .
  20. S2CID 84188968
    .
  21. S2CID 84437298
    .
  22. JSTOR 1541587
    .
  23. doi:10.1016/S0022-0981(02)00595-6
    .
  24. PMID 15302530
    .
  25. ^ As Chau et al., op. cit., note, "Despite its long history and a thorough knowledge of its toxicity and pharmacology, neither the pathway to TTX nor even the biogenic origin of TTX is known. The debate into whether TTX is derived from bacteria or is endogenous to the host animals is on-going and the only published study into the substrates of TTX biosynthesis proved inconclusive."
  26. PMID 23261990
    .
  27. PMID 30049784
    .
  28. ^ "Tetrodotoxin | Ligand page | IUPHAR/BPS Guide to Pharmacology". Guide to Pharmacology. International Union of Pharmacologists.
  29. PMID 18941294
    .
  30. ^
    PMID 5328391
    .
  31. S2CID 6117457
    .
  32. PMID 21543051
    .
  33. PMID 32896120
    .
  34. PMID 34207879
    .
  35. PMID 18067939
    .
  36. ^
    PMID 35580905
    .
  37. S2CID 98806870. Archived from the original
    (PDF) on 2016-03-04. Retrieved 2013-11-11.
  38. doi:10.1246/bcsj.43.3332
    .
  39. PMID 4642370
    .
  40. PMID 4642371
    .
  41. ^ Taber D (2005-05-02). "Synthesis of (-)-Tetrodotoxin". Organic Chemistry Portal. organic-chemistry.org.
  42. PMID 12862474
    .
  43. PMID 15366086
    .
  44. PMID 13129349
    .
  45. PMID 22073009
    .
  46. S2CID 23840469
    .
  47. ^ "Material Safety Data Sheet Tetrodotoxin ACC# 01139". Acros Organics N.V.
  48. ^ "Cyanides (as CN)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  49. ISBN 0-07-146891-9
    .
  50. ISSN 1057-9419
    . Retrieved 26 May 2012.
  51. ^
    PMID 10485519. Archived from the original on October 7, 2008.{{cite journal}}: CS1 maint: unfit URL (link
    )
  52. ISBN 9780702053627
    .
  53. ^ a b c "CDC – The Emergency Response Safety and Health Database: Biotoxin: Tetrodotoxin – NIOSH". www.cdc.gov. Retrieved 2016-01-03.
  54. ^ "T8024 Sigma Tetrodotoxin". Catalogue. Sigma-Aldrich. Retrieved 23 August 2015.
  55. ^ Kaempfer E, Scheuchzer Johannes Caspar, trans. (1727). The History of Japan …. Historia imperii Japonici. Vol. 1. London, England: J.C. Scheuchzer (ed.). pp. 134–135.{{cite book}}: CS1 maint: multiple names: authors list (link)
  56. PMID 11613509
    .
  57. ISBN 9781851094905
    .
  58. ^
    ISBN 0070202915
    .
  59. ^ a b Benzer T. "Tetrodotoxin Toxicity". Medscape. Retrieved 23 August 2015.
  60. PMID 8585093.Closed access icon
  61. PMID 7241765. Closed access icon
  62. ^ McNabb P, Mackenzie L, Selwood A, Rhodes L, Taylor D, Cornelison C (2009). "Review of tetrodotoxins in the sea slug Pleurobranchaea maculata and coincidence of dog deaths along Auckland Beaches" (PDF). Auckland Regional Council Technical Report 2009/108. Cawthron Institute for the Auckland Regional Council. Archived from the original (PDF) on 2015-09-23. Retrieved 2010-02-23.
  63. ^ Gibson E (15 August 2009). "Puffer fish toxin blamed for deaths of two dogs". The New Zealand Herald. Retrieved 19 November 2011.
  64. ^ a b 危険がいっぱい ふぐの素人料理 [Danger in fugu amateur cuisine] (in Japanese). Tokyo Bureau of Social Welfare and Public Health. Archived from the original on 28 January 2010.
  65. ^ 自然毒のリスクプロファイル：魚類：フグ毒 [Fish: fugu poison risk profile of natural poison] (in Japanese). 厚生労働省 (Ministry of Health Labour and Welfare (Japan)). Archived from the original on 27 September 2011.
  66. ^
    PMID 3775790
    .
  67. ^
    PMID 2339427
    .
  68. ^ a b Hines T (May–June 2008). "Zombies and Tetrodotoxin". Skeptical Inquirer. 32 (3): 60–62. Archived from the original on 2016-07-09. Retrieved 2015-08-23.
  69. ISBN 978-1-86094-814-5
    .
  70. ISBN 978-0-9626523-7-0
    .
  71. PMID 21655148
    .
  72. PMID 18243639
    .
  73. PMID 22412801
    .
  74. ISBN 0-7890-0553-0
    . Tetrodotoxin blocks the sodium currents and is believed to have potential as a potent analgesic and as an effective agent in detoxoification from heroin addiction without withdrawal symptoms and without producing physical dependence.
  75. S2CID 11221499
    .
  76. ^ "HHS and USDA Select Agents and Toxins 7 CFR Part 331, 9 CFR Part 121, and 42 CFR Part 73" (PDF). Archived from the original (PDF) on 17 January 2009. Retrieved 17 March 2013.
  77. ^ "Permissible Toxin Amounts". Federal Select Agent Program. United States Centers for Disease Control and Prevention. Retrieved 20 Feb 2017.
  78. ^ Miami Vice (1984–1990) Tale of the Goat. IMDb
  79. ^ Miranda K (26 November 2014). "Covert Affairs Recap: Starlings of the Slipstream". Movie News Guide. Archived from the original on 6 August 2018. Retrieved 25 July 2015.
  80. ^ "Covert Affairs: Starlings of the Slipstream (season 5, episode 12, original air date 13 November 2014)". USA Networks. 2015. Retrieved 25 July 2015.
  81. ^ "The Apothecary Diaries, Vol. 5, Chapter 25". Square Enix. Archived from the original on June 16, 2023. Retrieved July 13, 2022.
  82. ^ "The Apothecary Diaries, Vol. 7, Chapter 33". Square Enix. Archived from the original on February 2, 2023. Retrieved November 19, 2022.
  83. ^ Silverman R (January 21, 2024). "The Apothecary Diaries Episode 15". Anime News Network. Archived from the original on January 21, 2024. Retrieved 2024-02-27.
  84. ^ Silverman R (February 25, 2024). "The Apothecary Diaries Episode 20". Anime News Network. Archived from the original on February 25, 2024. Retrieved 2024-02-27.
  85. ^
    ISBN 978-0671502478
    .
  86. ISBN 978-0061695131
    .

Further reading

External links