-
Amanita
brunnescens
=> gastrointestinal irritant
-
Amanita
cokeri
-
Amanita
cothurnata
-
Amanita exitialis (a.k.a. Guangzhou
destroying angel)
The fruiting body of Amanita exitialis is small
to medium-sized. The cap is 40 - 70 mm wide, convex to applanate, sometimes
slightly depressed at center, glabrous, white, and sometimes cream-colored
over disc. Its margin is nonstriate and nonappendiculate, and the flesh
is white. The gills are free, white to whitish, and crowded; the short
gills are attenuate, plentiful, and in 2 - 3 ranks. The stem is 70 - 90
x 5 - 10 mm, white to whitish, glabrous, or sometimes with fibrillose squamules,
and subcylindric or slightly tapering upward. The apex is slightly expanded,
and the flesh is white. The stem's basal bulb is subglobose and 10 - 20
mm wide. The volva is on the bulb as a short, membranous limb. It is thin
and membranous, and the free limb is up to 7 mm high, inner and outer surfaces
of the limb are white. The annulus is apical to subapical, thin, membranous,
white, skirt-like, and often persistent (although it may be torn from stem
during expansion of cap). The spores measure (9.0-) 9.5 - 12.0 (-14.5)
x (8.5-) 9.0 - 11.5 (-13.0) µm and are globose to subglobose (rarely
broadly ellipsoid) and amyloid. Clamps are absent from the bases of basidia.
Unlike most other agarics, the basidia of this species are almost entirely
2-spored (rarely 1-spored). This mushroom grows in broad-leaved forest.
It was described from southern China and is only known from the type locality.
In mid-March of 2000, a disaster happened in Guangzhou, southern China
(Guangdong Prov.) due to eating this mushroom. 9 persons ate the mushroom,
only 1 of them survived.
-
Amanita
gemmata
-
Amanita
muscaria (fly agaric)
Epidemiology : the Soma hymns of the 3,000-year-old
sacred Indian book, the Rig Veda, have been interpreted as a glorification
of A. muscaria and its effects. Many tribes in Siberia used it for
centuries as a religious or recreational intoxicant, and although it has
now largely been replaced by vodka, some Siberians still prefer mushrooms.
Historical accounts suggest that the active principle is not destroyed
in the body, but is excreted unaltered in the urine. Probably by watching
their reindeer, which have a fondness for urine, the Siberians learned
that the inebriant could be recycled. When mushrooms were in short supply,
and only the richer tribesmen could afford them, the poor folk waited for
the guests to relieve themselves, then drank the intoxicating liquid.
=> muscarine : it is an agonist
of M AChRs
Symptoms & signs : within 30 minutes
to 2 hours of being consumed, it causes mycetismus nervosus (perspiration,
salivation, lachrymation (PSL) syndrome, persistent peristalsis =>
diarrhea
,
retching, dizziness (and nausea
and vomiting,
if too many mushrooms have been eaten), miosis, blurred vision, acute excitement,
delirium, stupor, and coma, slow heartbeat, and a excessive hypertension
a purpuric rash and transient hepatic, muscular, renal and cutaneous damage.
It induces muscle spasms, then a deep sleep, full of fantastic dreams,
lasting about 2 hours. On waking, the subject usually experiences a 'good
trip': a feeling of elation that persists for several hours. People often
become hyperactive, making compulsive and uncoordinated movements, perhaps
talking non-stop, and having altered perceptions of reality. Occasionally
the experience is a 'downer.' The only real danger here is that the heart
may actually stop, if enough toxin has been absorbed. This has happened
only rarely, and then in patients with existing cardiovascular disease.
Treatment : carefully administered i.v.
atropine.
=> ibotenic acid : although
fresh mushrooms contain ibotenic acid, which has some effect on the nervous
system, dried mushrooms have been found to be much more potent because
ibotenic acid degrades to muscimol (an
agonist of GABAA receptors)
on drying. Muscimol is 5-10 times more psychoactive than ibotenic acid.
Dried mushrooms retain their potency for 5-10 years. Although very few
deaths have been reported from this kind of poisoning, 10 or more mushrooms
can constitute a fatal dose. In most cases, the best treatment is no treatment.
Recovery is spontaneous and complete within 24 hours. If many mushrooms
have been eaten, severe convulsions may have to be controlled, and the
stomach should be emptied. On no account should atropine
be given: it will exacerbate the symptoms.
=> stizolobic acid is a competitive
antagonist of the quisqualate-type receptor
=> stizobinic acid
=> aminohexadienoic acid
=> chlorocrotylglycine
-
Amanita
ocreata
=> amatoxins
-
Amanita
pantherina (a.k.a. panther amanita)
=> muscarine : it is an agonist of
M
AChRs,
causing mycetismus nervosus (tearing, sweating, salivation, persistent
peristalsis, retching and nausea
and vomiting,
contraction of ciliary muscles and miosis,
acute excitement, delirium, and coma)
-
Amanita
phalloides (death cap)
=>
-
phallotoxins : a group of heptapeptides
that inhibit microtubule polymerization
-
phallacidin
-
phallisacin
-
phalloidin / phalloidine => mycetismus
choleriformis (abdominal
pain,
nausea
and vomiting,
diarrhea,
bloody stools, protein and casts in the urine, malaise, and cyanosis)
-
phallisin
-
phalloin
i.v. LD50 in mice is 2 mg/kg (10 times more lethal than cyanide),
but when taken by mouth, they have no effect (they may be neutralized or
broken down by digestive juices, or may not be absorbed by the gut)
-
amatoxins : a group of bicyclic octapeptides
occurring in some Amanita, Galerina
and Lepiota
species, inhibit RNA polymerase II
> RNA polymerase III (RNA polymerase I is insensitive) and induce deficient
protein synthesis resulting in cell death, but might also exert toxicity
through inducing apoptosis. Actively toxic when eaten (LD50
= 0.1 mg/kg). Target organs are intestinal mucosa, liver and kidneys.
Symptoms & signs : latent period of 6-24
hours => nausea and violent
vomiting,
diarrhea
and abdominal
pain,
which last for a day or so => brief, misleading remission of symptoms =>
dehydration and electrolyte derangement,collapse of kidney and liver function,
with secondary effects on the heart and brain, leading to coma and death.
Laboratory examinations : Wieland or
Meixner test involves taking a piece of mushroom, placing it on a lignon
containg paper, such as newspaper, dropping a drop of hydrochloric acid
onto the mushroom flesh, and observing the color that appears : the test
is based on a reaction between amatoxin and lignin, which is catalyzed
by the acid. Otherwise a small quantity (a drop) of freshly squeezed “juice”
from the mushroom on a sheet of pulp paper (newsprint paper). After the
location of the spot has been marked and the area dried using low temperature
air from a blow dryer, a drop of concentrated hydrochloric acid should
be placed on the spot. If a blue color appears within 20 minutes after
the addition of the hydrochloric acid, the mushroom tested is positive
for amanitoxins. The mushroom flesh can be dried or fresh, and even flesh
pieces as old as 14 years have been tested with correct results. A control
involving the placement of a drop of HCl on an area of the paper without
mushroom specimen should be run simultaneously, as false-positives have
occurred. Exposure to sunlight or excessive heat may affect the results
of the test. Although the Meixner test has a good detection limit for toxic
amounts of a-amanitin
(> 2 mg), a positive Meixner reaction does not
adequately distinguish between a-amanitin and
other mushroom indoles, e.g. psilocin, 5-hydroxytryptamine,
and 5-methoxy-N,N-dimethyltryptamineref)
Therapy :
-
optimum symptomatic and supportive care : careful monitoring of electrolyte
and fluid balance, and blood sugar, with appropriate replacement therapy
as required. Liver and kidney functions must be closely followed. If kidney
and/or liver failure occurs, haemodialysis and/or haemoperfusion may be
necessary. In addition, various researchers have suggested several other
strategies to support the damaged liver or kidneys: intravenous infusion
of B vitamins, vitamin K, Penicillin-G, corticosteroids, and thioctic acid
(a coenzyme in the Krebs cycle).
-
removal of toxins :
-
if the condition is diagnosed within 1-2 hours, it is obviously appropriate
to empty the stomach by emesis and gastric lavage
-
haemodialysis (circulating the blood through a semipermeable membrane bathed
in an isotonic medium) is used in long-term treatment of kidney failure,
or until a transplant becomes available. Its use in Amanita poisoning
is questionable, since it removes substances of molecular weight 300 or
less. Amanitin itself has a molecular weight of 900, and it may often become
complexed with much larger molecules, such as proteins. Nevertheless, in
serious cases, where kidney failure threatens, haemodialysis may be useful
under heading
-
haemoperfusion (circulating the blood over activated charcoal) is used
to support the detoxifying function of failing livers. It has been used
experimentally to treat Amanita poisoning in recent years, and has
been shown to remove some toxin from amanitin-spiked blood. Unfortunately,
the amounts of amanitin detected in the blood of poisoning victims are
usually very low, especially if more than 12 hours have elapsed since the
mushrooms were eaten. Keeping in mind the possible unfavourable effect
of haemoperfusion on a blood coagulatory pattern already unbalanced by
the effects of the toxin, this technique should be applied with caution.
It may, of course, be indicated if the effects of the toxin cause liver
failure.
-
apheresis : again, the actual kinetics of amanitin in the body are not
yet well-enough understood for us to be sure which blood fraction, if any,
should be replaced. This technique may prove to be of value when the movements
of amanitin in the body are better understood.
-
increase urine excretion by giving intravenous fluids and an appropriate
diuretic
-
silibinin, benzylpenicillin and acetylcysteine, might have a role in limiting
the extent of hepatic damage
-
a French physician, Dr. P. Bastien, has developed a new treatment for Amanita
poisoning. It has 3 parts:
-
intravenous injections of 1 gram vitamin C twice a day
-
2 capsules of nifuroxazide 3 times a day
-
2 tablets of dihydrostreptomycin 3 times a day.
The treatment is supplemented by measures to control fluid and electrolyte
balance, and by penicillin. Bastien successfully treated 15 cases of A.
phalloides poisoning between 1957 and 1969. In 1974 he ate 65 g of
A.
phalloides and survived. In 1981 he ate 70 g of A. phalloides
and again successfully treated himself. It is reported that the Bastien
treatment is now used throughout France, where it saves the lives of all
those whose treatment has not been delayed until massive liver and kidney
damage has occurred.
Several mycophagous species of Drosophila (the fruit fly genus)
eat poisonous amanitas with impunity. It has been demonstrated that they
can survive concentrations of amanitin hundreds of times greater than can
their fruit-feeding relatives. They are, in fact, the most amanitin-tolerant
species known. Although the agarics in which mycophagous drosophilas breed
are also sought out by crane flies and wood gnats, much larger insects,
those competitors cannot survive in mushrooms that contain amanitin.Drosophila
larvae in amanitin-containing mushrooms are never parasitized by the nematode,
Howardula.
This is an important selective advantage, because parasitized adults, which
can represent up to 35% of the population, are often sterile or have reduced
breeding success
-
phallolysin, a mixture of 2-3 cytolytic
proteins (all of Mr 34 000)
-
antamanide, a cyclic peptide, which counteracts
phalloidin
-
Amanita
smithiana (confused with edible pine mushroom or matsutake (Tricholoma
magnivelare) in Pacific northwest USA and in southwestern
British Columbia, Canada) => gastrointestinal symptoms range from 20' to
12 hours, and presentation in acute
renal failure
ranges from 4 to 6 days postingestion
=> aminohexadienoic acid
=> chlorocrotylglycine
-
Amanita
proxima (confused with edible Amanita ovoidea in southern
France) => gastro-intestinal symptoms and acute
renal failure
-
Amanita
rubescens (blusher)
=> rubescenslysin : a cytolysin
-
Amanita
vaginata (grisette)
-
Amanita
verna (a.k.a. destroying angel)
=> phalloidin / phalloidine => mycetismus choleriformis
(abdominal
pain,
nausea
and vomiting,
diarrhea,
bloody stools, proteinuria,
cylindruria,
malaise, and cyanosis)
-
Amanita
virosa (destroying angel)
Copyright © 2001-2005 Daniele Focosi.
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