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For discussing the functions of different structures of all organisms.

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Dr.Stein
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Post by Dr.Stein » Fri Feb 24, 2006 3:38 am

Hehe, as you may know, there are bunches of "funny" words in Immunology, as:
- "naive" lymphocyte
- virus "hijacks" infected cell
- the "fate" of lymphocyte
- "educating" macrophage
- "frustrating" lymphocte
- "presentation" of peptide by MHC to T cell
- etc.

:lol:
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victor
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Post by victor » Sat Feb 25, 2006 12:01 pm

:shock: I don't know about "fate" and "frustrating"...
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Post by Dr.Stein » Mon Feb 27, 2006 7:45 am

About FATE:
As you already know, there are two kinds of lymphocytes, i.e. B cell and T cell. Both are produced in bone marrow. The one that will develop to be B cell will remain in bone marrow, whereas the one that will develop to be T cell will migrate to thymus. That's the fate of lymphocyte.

Another fate. In the development of T cell, there is a time when T cell bring both CD8 and CD4 marker. Eventually, T cell will bring only CD8 or CD4 (double selection). That's the fate of T cell.

About FRUSTRATING:
When infecting pathogens are excessive while our body cannot produce adequate immune response, both humoral and/or cellular, to elliminate them, lymphocyte will not do anything. It will show an increasing pathogens, increasing lymphocytes, but no increasing immune response. One example.
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victor
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Post by victor » Thu Mar 02, 2006 1:29 pm

:lol: that's really frustated lymphocyte...it's just like they're trying to say,"this time we're give up, just hang your hope in antibiotics my master..." :lol:
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Nite
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Post by Nite » Mon Mar 27, 2006 4:36 pm

@Dr Stein
.....with appropriate MHC to T-cell that will recognize and determine whether it is pathogenic or nonpathogenic material. It is T-cell job to take action whether we will generate immun response or immune tolerance.


T cell recognise n determine if the antigens are pathogenic or not? How do the T cells do it? Is it through the positive selection of T cell during T cell maturation?

In cytoplasm there is a giant protein complex known as proteasome that will cut viral protein into peptides. After some steps of reaction (if you need this in detail, I'll explain it later, this is a bit complicated), eventually the peptide will bind to newly synthesized MHC-I and externalize to be presented to T-cell


This part is about MHC Class I antigen processing pathway rite...
ie. --> intracellular peptides bind to ubiquitin molecules. Peptides get linearised and transport to proteasome. Proteasome breaks down peptides into smaller peptides and smaller peptides get into ER through TAP protein.. and so on... rite?

and my question is: How does the cell differentiate which intracellular peptides to be processed by the MHC Class I pathway? Since there are a lot of peptides in the cells... is it that some receptor inside the cells must bind to the intracellular Ags first?




@vic

they fuse their capsids with the endosome and release their genetic materials..


If the viral capsid fused with the endosome, means that the viral contents (ie. DNA/RNA) is released into the cytoplasm rite..
But the DNA/RNA target is to get into the nucleus rite...
How do the viral DNA/RNA move into the nucleus? and wouldnt the DNA/RNA be digested by the nuclease in the cytoplasm first before they can move into the nucleus?


Hope i din ask too much;p

Nite:)
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victor
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Post by victor » Thu Mar 30, 2006 8:01 am

@Nite
That's still a Mr.Mystery..:lol: scientists till now, haven't discovered it yet...but some mechanisms have already hypothesized, like the virus' genetic material code a kind of protein fusion to protect the DNA/RNA from nucleases...
Q: Why are chemists great for solving problems?
A: They have all the solutions.

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