Question

Prep for USMLE Forum

» Log in | Register

Forum

Step 1

Match

Prep4USMLE Forum » USMLE Step 1 Forum » Pathology Forum

Question

Author

19 Posts

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/08/06 - 03:05 PM

A study is conducted to investigate the pathogensis of atherosclerosis.The investivators have developed a genetically modified mice that have hypercholestrolemia and spontaeously develop atherosclerosis.Next, the investigators selectively delete individual genes in order to determine the factors that are critical to the development of atherosclerosis.Deletion of the gene encoding for which of the following is most likely to reduce the experimentally observed atherosclerosis in these modified mice ?

A.Von Willebrand factor

B.Homocysteine

C.T cell receptor

D.Endothelin

E.Fibrillin

F.LDL receptor

G.Factor Vlll

H.Apolipoprotein

___________________
My best friends are these Gentlemen :Why & How.

ssrpk
Forum Fanatic
avatar

Topics: 154
Posts: 2,819

10/08/06 - 03:23 PM

i wud have selected H if it were apolipoprotein (a), as none of the other seems appropriate!

whtz the asnwer?

___________________
life is guud

doc179
Forum Guru

Topics: 67
Posts: 1,217

10/08/06 - 07:01 PM

http://www.talkorigins.org/faqs/information/apoli...

this link is suggestive that the answer is apolipoprotein

On the other hand, homocysteine is a known etiological factor for atherosclerosis (p.190 of goljan)

Edited by doc179 on 10/08/06 - 07:37 PM

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/09/06 - 10:08 PM

the correct answer is C. T-cell receptors

___________________
My best friends are these Gentlemen :Why & How.

klimt
Forum Guru

Topics: 27
Posts: 605

10/10/06 - 01:58 AM

Can you please explain your answer, drfax?

___________________
Traveler, there are no roads. Roads are made by walking.

ssrpk
Forum Fanatic
avatar

Topics: 154
Posts: 2,819

10/10/06 - 08:15 PM

C??????????????????

yeah plz explain!

___________________
life is guud

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/10/06 - 11:19 PM

Hi

really that was my reflection when saw the answer too, but that is the explanation:

deletion of T cell receptor gene prevents T cell development.Early in the course of atheroma formation the T cells adhere to VCAM 1 on activated endothelial cells and migrate into the vessel wall. THese T cells, secret a variety of pro-inflammatory molecules that recriut and activate monocytes and smooth muscle cells and perpetuate chronic inflammation of the vessel wall.

___________________
My best friends are these Gentlemen :Why & How.

doc179
Forum Guru

Topics: 67
Posts: 1,217

10/10/06 - 11:52 PM

Thank you very much. Do they also say why its not neither apolipoprotein nor homocystenine?

klimt
Forum Guru

Topics: 27
Posts: 605

10/11/06 - 08:18 AM

thanks!

___________________
Traveler, there are no roads. Roads are made by walking.

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/11/06 - 10:43 AM

#10

Hi doc179

If u delete LDL receptors u gonna promote atherogenesis by preventing LDL uptake by the liver and therefore increase in LDL level in serum.

Homocystine is important in atherogensis but there is no evidence about its role in initiation of atheroma.(Robbins Pathologic Basis of Disease 7th. Edition 2005)

Good luck

___________________
My best friends are these Gentlemen :Why & How.

doc179
Forum Guru

Topics: 67
Posts: 1,217

10/11/06 - 12:43 PM

#11

apolipoprotein, not LDL receptor. thats ok. may be its the same explanation that it has no role in intiating an atheroma. Thank you

proctalgia
Forum Senior
avatar

Topics: 2
Posts: 209

10/12/06 - 05:37 AM

#12

drfax wrote:
Hi

really that was my reflection when saw the answer too, but that is the explanation:

deletion of T cell receptor gene prevents T cell development.Early in the course of atheroma formation the T cells adhere to VCAM 1 on activated endothelial cells and migrate into the vessel wall. THese T cells, secret a variety of pro-inflammatory molecules that recriut and activate monocytes and smooth muscle cells and perpetuate chronic inflammation of the vessel wall.

tnk for the explanation. pls clarify.------>How is it possible to prevent T cell development by knocking out T cell receptor gene?

MD_toronto
Forum Junior

Topics: 2
Posts: 27

10/12/06 - 09:10 AM

#13

B

Homocystiene is one of the factor that develops atherosclerosis. That's what question stem asking.

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/12/06 - 12:26 PM

#14

HI proctalgia,
T cells receptor engagement in thymus during development is essential for T cell survival.
Good luck

___________________
My best friends are these Gentlemen :Why & How.

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/12/06 - 12:30 PM

#15

MD_toronto wrote:
B

Homocystiene is one of the factor that develops atherosclerosis. That's what question stem asking.

There is no evidence about role of homocystine in INITIAL development of atherosclersis. Robbins Pathologic Basis of Disease 7th. Edtion

___________________
My best friends are these Gentlemen :Why & How.

drfax
Forum Elite
avatar

Topics: 23
Posts: 262

10/12/06 - 12:36 PM

#16

doc179 wrote:
apolipoprotein, not LDL receptor. thats ok. may be its the same explanation that it has no role in intiating an atheroma. Thank you

Hi doc179
apolipoprotein deletion is the same as LDL receptor deletion gene, remmember familial hypercholestrolemia (def. LDL rec.) and abetalipoproteinemia (def. apolipo.)
that are a risk factor for atheroma formation.

Good luck

___________________
My best friends are these Gentlemen :Why & How.

doc179
Forum Guru

Topics: 67
Posts: 1,217

10/12/06 - 01:10 PM

#17

yes thank you drfax I came across the question in the book I have and I must say I have not been thinking about familial hypercholesterolemia. good question.

MD_toronto
Forum Junior

Topics: 2
Posts: 27

10/12/06 - 04:00 PM

#18

C

my mistake w/ B. didn't read question carefully. T-cell will be best choice and well explained above.

what are other initaiting factors for development of atheroscelrosis? just to for discussion..

epica

10/12/06 - 09:14 PM

#19

what is correct ans?
C or B?

You don't have permission to post.