Misrati
Forum Junior
Topics: 10
Posts: 48
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25 YO c/o recurrent episodes of abdominal cramps, diarrhea that sometimes bloody and feels something annoying him while defecating , he got also both lower limbs prasthesia
lab studies shows borderline WBC count ,high MCV , low Hb , high ESR , otherwise normal , Bone Marrow aspiration has been sent to the lab ,yet not received ! by which mechanism the suspected substance lead to the above signs and symptoms ?
a-Auto-Immune pateren
b-infection lead to decreased surface area
c-projecting cysts lead to increased surface area
d-decreased it solubility due to DNA replication errors
c-mutation in hMSH2 gene
d-increased membrane thickness
e-decrease membrane thickness
f- loss of substance ionization
g-loss of substance -ve charge
h-b+f are correct
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| new_n_lost
Politically InCorrect
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a-Auto-Immune pattern > UC ??
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| McBrainy
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just A gives a sense to me.
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| Misrati
Forum Junior
Topics: 10
Posts: 48
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OK , let's be more clear , its an integration question , not only pathology , you may need to use your pharama and / or biochem knewledge ...here its a bout a nutritional substace defect that body can't get benefit of it , so lead to the mentionaed neurological symptoms.. its a 2 or 3 steps question :
1- you need to know the disease
2- what's really lead to the neurological symptoms
3-why ? the mechanism ; the concept
I'm not making up stories , its a question I got it from Dr.Raymon
so , please explain why , when you pick up any answer ..
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| arlete
Intern in 2009!!!!!
Topics: 30
Posts: 2,240
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It's chronic arsenic poisoning. Arsenic blocks the Krebs cycle and interrupts oxidative phosphorylation - so I think it's F.
Am I too far from the truth? 
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| angel23
Forum Guru
Topics: 38
Posts: 780
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i think this is a diphyllobothrium infection.....
coz patient has diarrhoea + increased MCV (megaloblastic anemia)+neurological problems(def of vit B12)....
but i dnt knw which mechanism wud fit in here....
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| Tiff
Forum Guru
Topics: 54
Posts: 563
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I'll go with A.
Ok. This person is suffering from a B12 deficiency, megaloblastic, macrocytic anemia which can cause paresthesias. B12 is needed for synthesizing methione which is necessary for myelin.
B12 with intrisnic factor is absorbed in the terminal ileum. Crohn's disease affects the entire GI tract especially the terminal ileum (I believe about 80% of the time). Therefore I'm inclined to believe that this patient is suffering from Crohn's Disease.
Crohn's disease can also be affecting this person's rectum and anus causing the "annoying" sensation - which is probably due to a fistula or anal skin tag. Furthermore, diarrhea, even bloody diarrhea as well as abdominal cramps can all be seen in a person with Crohn's. Also, ESR (which measures inflammation) is definitely elevated in Crohn's.
Lastly, Crohn's disease is due to an autoimmune process. Therefore the answer should be A. 
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| angel23
Forum Guru
Topics: 38
Posts: 780
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good going tiff....
u r right...!!
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| Misrati
Forum Junior
Topics: 10
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you're almost in your way guys , but not yet !! , however you got 2 points , but missed the 3d one " the mechanism" !!
it is Crohn's disease due to vit .B12 def. but by which mechanism patients with crohn's can't get benefit of B12 ? why their GI can't absorb the vitamin ??
Although the cause of Crohn's disease is not known, it is believed to be an autoimmune disease that is genetically linked..Nonetheless , in the question we asked about the mechanism of missing B12 to be picked by patiet's GI , not the mechanism of the original disease !!
again , thx Angel23 , you got one "B12" , and good job tiff you got two"Crohn's and B12" , just think about the 3d point " the mechanism "
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| Misrati
Forum Junior
Topics: 10
Posts: 48
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I meant, yet not the right answer been picked
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| Tiff
Forum Guru
Topics: 54
Posts: 563
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Ok. The only other thing I can think of is that since Chron's has transmural inflammation, there would be increased membrane thickness - choice D.
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| SmokyWaters
Forum Elite
Topics: 6
Posts: 458
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I dunno if its stupid or not...
when I read the question I thought its some parasitic infection like diphylobothrium latum
causing B12 deficiency and the infection is decreasing the surface area :S
makin H as the possibility...
but then the discussion is all about crohn's which also fits the picture...
but the problem is ...there is none that matches the mechanism...the mechanism of crohn's vit B12 deficiency is increased inflammation..decreased surface area and perhaps loss of some surface ionization may be.. m all confused...
:S
increased thickness of membrane? what membrane are we talkin about here? :S I dunno
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| SmokyWaters
Forum Elite
Topics: 6
Posts: 458
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| SmokyWaters
Forum Elite
Topics: 6
Posts: 458
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my answer's H 
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| Tiff
Forum Guru
Topics: 54
Posts: 563
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SmokyWaters - it can't be diphyllobothrium latum. It doesn't present with bloody diarrhea. In fact it's usually asymptomatic and doesn't fit in with the clinical picture of this patient who is also having some "annoying" sensation with BM indicating that something is there such as a fistula or skin tag.
At least that's how I see it.
If you think otherwise, can u explain your thought process on how all the signs & symptoms fit?
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| SmokyWaters
Forum Elite
Topics: 6
Posts: 458
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well classically YES you are right.. it doesnt present with bloody stools...
I am totally confused.. :S
and you are right.. tiff.... I rejected my answer when I again thought that it can be crohn's but what fits it?
increased thickness of membrane?
I guess that fits it because that seems to be the only related thing to crohn's
there was no thought process behind my reply...all I thought was to choose the most wierd one 
secondly annoying sensation does occur in parasitic infections but its more related to IBDs ...
and fistulae arent the reason.. usually the inflammatory transient blockage to the flatus/feces is the cause...
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| Tiff
Forum Guru
Topics: 54
Posts: 563
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Ok. Yeah - I was thinking that the membrane thickness might be referring to the increased thickness of the tract due to the disease. I wish it was more clear what type of annoying sensataion. Either way it works for IBD.
Great question. I'd like to know what the answer is for sure to confirm.
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| Misrati
Forum Junior
Topics: 10
Posts: 48
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Tiff wrote:
Ok. The only other thing I can think of is that since Chron's has transmural inflammation, there would be increased membrane thickness - choice D.
Got that tiff , I really salute you for this
the correct answer is " D"
Crohn's disease shows a transmural pattern of inflammation, meaning that the inflammation may span the entire depth of the intestinal wall , so GI wall in Crohn's much thicker which make it harder to the substance to cross the wall .
as we know from our pharm and biochem , Diffusion equation : since Diffusion "absorption" of substance directly related to lipid solubility,Concentration gradient,surface area and vascularity ...and inversely related to T"membrane thickness" and square root of Log moleculare weight "ptn-bound"
another example is " Lung fibrosis"
so , only choice "D" matches the clinical scenario of cronh's and concept of unnabsobable vit.B12 "water soluble,ionized ".
I know , its not easy question , but you may score sky high and beat the board by answering such questions in the exam ..GOOD LUCK 4 ALL OF YOU GUYS
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