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cellular mechanisms that result in symptoms of cholera

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cellular mechanisms that result in symptoms of cholera

Postby tesla93 » Mon Nov 19, 2012 9:59 pm

Hi all,

I''m trying to understand how cholera symptoms are developed, and all I know so far is that the cholera toxin (CT) is responsible for the main symptom of cholera, which is secretory diarrhea. More specifically, CT is an A-B5 subunit-type exotoxin released in the small intestine, but I can't really find how specific cellular mechanisms that cause this and other symptoms (nausea, dehydration, vomiting, muscle cramps). Thanks for looking!
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Postby tesla93 » Mon Nov 19, 2012 10:35 pm

Just wanted to add of the mechanisms is direct stimulation of chloride secretion by enterocytes, which is a result of the cholera toxin, but I don't really understand what this is/I can't find much information on it. This mechanism is responsible for secretory diarrhea
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Re: cellular mechanisms that result in symptoms of cholera

Postby naachiz » Mon Nov 26, 2012 11:50 am

Cholera is an acute Diarrhoeal disease caused by V. Cholerae. It is seen in many countries of the world mainly the poor third world countries. Libya has no epidemic cases since 1970. Cholera is no longer the dreaded disease of the past because we can prevent deaths with Oral Rehydration Salt solution.

You can read more about Cholera on these slides; ... re_Slides_
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Postby MarkHolland » Wed Dec 05, 2012 7:49 am

Cholera symptoms and signs include a rapid onset of copious, smelly diarrhea that resembles rice water and may lead to signs of dehydration.For example, vomiting, wrinkled skin, low blood pressure, dry mouth, rapid heart rate.


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Postby adithya528 » Tue Dec 11, 2012 1:49 pm

The cholera toxin (CTX or CT) is
an oligomeric complex made up
of six protein subunits: a single
copy of the A subunit (part A),
and five copies of the B subunit
(part B), connected by a disulfide
bond. The five B subunits form a
five-membered ring that binds to
GM1 gangliosides on the surface
of the intestinal epithelium cells.
The A1 portion of the A subunit
is an enzyme that ADP-ribosylates
G proteins, while the A2 chain fits
into the central pore of the B
subunit ring. Upon binding, the
complex is taken into the cell via
receptor-mediated endocytosis.
Once inside the cell, the disulfide
bond is reduced, and the A1
subunit is freed to bind with a
human partner protein called
ADP-ribosylation factor 6 (Arf6).
[13] Binding exposes its active
site, allowing it to permanently
ribosylate the Gs alpha subunit of
the heterotrimeric G protein. This
results in constitutive cAMP
production, which in turn leads
to secretion of H2O, Na+, K+, Cl−,
and HCO3− into the lumen of the
small intestine and rapid
dehydration. The gene encoding
the cholera toxin is introduced
into V. cholerae by horizontal
gene transfer. Virulent strains of
V. cholerae carry a variant of
temperate bacteriophage called
CTXf or CTXφ.
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