Step I ETEC-heat stable toxin

[Zzmed]

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FA errata says that the second entry for ETEC in page 152 in FA is to be deleted.

I don't understand that since ETEC has both heat labile and heat stable toxins.

Any thoughts?

 

[withrye]

FA errata says that the second entry for ETEC in page 152 in FA is to be deleted.

I don't understand that since ETEC has both heat labile and heat stable toxins.

Any thoughts?

As far as I can tell, ETEC has ST and it acts though cGMP, just like Y. enterolitica's toxin. I don't really know why FA has that erratum.

 

[Kovach]

FA errata says that the second entry for ETEC in page 152 in FA is to be deleted.

I don't understand that since ETEC has both heat labile and heat stable toxins.

Any thoughts?

ETEC can produce LT and ST, don't get confused- even Errata needs it's own Errata. And 👎 for FA 2012. I was so angry when I released there are mistakes in Errata even!

 

[Phloston]

FA is not wrong here. I double-checked the errata.

They're not saying to erase the fact that ETEC has a heat-stable toxin. They're saying that you should remove it from the headline of "increased fluid secretion."

Only heat-labile toxin induces increased fluid secretion; heat-stable toxin causes decreased reabsorption of fluid.

HL-toxin causes active Cl- efflux into the lumen and increased secretion.

HS-toxin prevents Cl- from entering the enterocyte.

That being said, cholera causes increased secretion and Y. entercolitica causes decreased reabsorption.

 

[withrye]

FA is not wrong here. I double-checked the errata.

They're not saying to erase the fact that ETEC has a heat-stable toxin. They're saying that you should remove it from the headline of "increased fluid secretion."

Only heat-labile toxin induces increased fluid secretion; heat-stable toxin causes decreased reabsorption of fluid.

HL-toxin causes active Cl- efflux into the lumen and increased secretion.

HS-toxin prevents Cl- from entering the enterocyte.

That being said, cholera causes increased secretion and Y. entercolitica causes decreased reabsorption.

This doesn't explain why Y. enterolitica is still under the "increase fluid secretion" section when its mechanism (and the ST of ETEC) is increased cGMP and decreased reabsorption.

 

[Phloston]

I don't have FA in front of me so I'm not able to comment on the specifics of their format / headings, but for all intents and purposes, cholera toxin and HL-toxin, as well as Y. enterocolitica toxin and HS-toxin, should be viewed as having MOAs mirroring one another. So if FA made changes to the heading of ETEC HS-toxin, then those changes should also apply to Y. enterocolitica.

 

[Zzmed]

Maybe they want to say that the overall result is increased fluid in the intestinal lumen (either due to increased secretion or decreased reabsorption). That's why the point that Phloston raised didn't cross my mind in the first place.

 

[Old Style Nanny]

HL-toxin causes active Cl- efflux into the lumen and increased secretion.

HS-toxin prevents Cl- from entering the enterocyte.

That being said, cholera causes increased secretion and Y. entercolitica causes decreased reabsorption.

This. However, isn't the action of incr cGMP primarily towards preventing Na+ influx (and so the water) than the Cl- influx?

Also, another question on a related topic to you. What if your result comes out tomorrow? Are you prepared for it?

 

[Greenbayslacker]

.

 

[withrye]

I'm still not understanding what exactly the table is supposed to say.. is it:

a) ETEC has HL-toxin & HS-toxin, and Y. enetero also has HS-toxin?
or
b) ETEC has HL-tox & Y. entero has HS-toxin?

thanks!

I wonder if this table might have been fixed in FA 2013, if anyone has it?

ETEC has LT and ST.

Y. enterolitica has ST.

Both stable toxins work though cGMP.

 

[Greenbayslacker]

.

 

[Phloston]

This. However, isn't the action of incr cGMP primarily towards preventing Na+ influx (and so the water) than the Cl- influx?

Na+ and Cl- follow one another. I said this loosely, but it would be like saying H+ is secreted in the stomach vs HCl; since HCl is a strong acid, you can get by with just saying H+.

Also, another question on a related topic to you. What if your result comes out tomorrow? Are you prepared for it?

I'm pretty sure it won't come out tomorrow. I had read that because of the holidays, it'll likely take four, not three, Wednesdays. Either way, I'd be thankful if it comes out tomorrow. I need to move on with my life. And I also just need to get back full-throttle on my PhD again. One door closed and another open. Brisbane is 14 hours ahead of New York. Over here, it's already Wednesday. I'll need to check "Thursday morning."

 

[Old Style Nanny]

More like the midnight since I've heard it comes out around 9-10 AM PST (I could be wrong though). Anyway, have you completed your major exam prep & experience post? I am assuming you would post it along with your result once it comes.

 

[Phloston]

More like the midnight since I've heard it comes out around 9-10 AM PST (I could be wrong though). Anyway, have you completed your major exam prep & experience post? I am assuming you would post it along with your result once it comes.

I had started writing a bit the day or two after my exam, but these past few weeks I've actually just been traveling a lot and haven't had much time for it. Hopefully I'll have the motivation to just sit down and write once the results come through. But you have to remember that it's summer here in Australia and every day right now is a beach day 🙂 Even this morning I was like, "I don't feel like working on my PhD right now, so I won't." But maybe I will tomorrow or the next day..