View Thread

Atheists Today » Easy Reading » Education
 Print Thread
Brain Farts
Solidsquid
Okay, I have some old Q&As over brain development, anatomy and physiology. So I figured I’d share that knowledge here with any interested. If anyone wants to know a bit more about what is posted, just let me know and I’ll do what I can to further explain things.

Describe the involvement of axon growth and guidance, target selection or apoptosis in a clinical condition, citing relevant literature.


Apoptosis is Greek which means, “falling from” or “falling away” and is defined by Wolf and Green (2002) as “a conserved cellular suicide program that eradicates excess or potentially dangerous cells”. This necessary program for suicide in cells can also contribute to the progression of some diseases and disorders. One particular disease in which this has become a salient point is Alzheimer’s disease, amongst a list of other disorders and diseases (Chamond, Anon, Aguilar and Pasadas, 1999).

Detection of cell cycle proteins have been found in human and rat models of Alzheimer’s in several studies (Guo et al., 1998; Gibson, 2001). It has also been substantiated through detection of DNA replication that an ectopic cell cycle is involved which precedes neuronal death (Yang et al., 2001; Herrup et al., 2004) which can lead to apoptosis. The pattern of the cell death itself occurs in such a fashion that it is consistent with apoptosis due to the fact that the cells do not lie together but individually (Siegel et al., 2006).

For apoptotic cell death, one would expect to find apoptotic proteins increased – which is exactly what has been found. Guo et al. showd that the Par-4 (Prostate Apoptosis Response-4) protein expression is increased in neurons that are “vulnerable”. Later, Guo et al. (2001) showed that their earlier findings to be substantiated. They found that Par-4 increases the secretion of the amyloid β peptide 42 via a caspase-dependent pathway. It was found that inhibition of caspase activity by a broad spectrum inhibitor weakened the Par-4 induced peptide production. Also, implicated is p53 (Cellular tumor antigen p53) protein which is involved in regulation of the cell cycle, DNA repair and can initiate apoptosis. Ohyagi et al. (2005) found that Aβ 42 activates the p53 promoter subsequently leading to p53 induced apoptosis. All these activities interact within the brain of Alzheimer’s patients – specifically the hippocampus to produce the cognitive deficits we see as a result and “support a role for apoptosis” (Siegel et al., 2006).

References

Chamond, R., Anon, J., Aguilar, C. and Pasadas, F. (1999). Apoptosis and disease. Alergologia e Immunologia Clinica, 14, 367-374.

Gibson, R. (2001). Does apoptosis have a role in neurodegeneration? British Medical Journal, 322, 1539-1540.

Guo, Q., Fu, W., Xie, J., Luo, H., Sells, S., Geddes, J. et al. (1998). Par-4 is a mediator of neuronal degeneration associated with the pathogenesis of Alzheimer disease. Nature Medicine, 4, 957-962.

Guo, Q., Xie, J., Chang, X. and Du, H. (2001). Prostate apoptosis response-4 enhances secretion of amyloid β peptide 1-42 in human neuroblastoma IMR-32 cells by a caspase-dependent pathway. Journal of Biological Chemistry, 276, 16040-16044.

Herrup, K., Neve, R., Ackerman, S. and Copani, A. (2004). Divide and die: Cell cycle events as triggers of nerve cell death. Journal of Neuroscience, 24, 9232-9239.

Ohyagi, Y., Asahara, H., Chui, D., Tsuruta, Y., Sakae, N., Miyoshi, K. et al. (2005). Intracellular Aβ42 activates p53 promoter: a pathway to neurodegeneration in Alzheimer’s disease. FASEB Journal, 19, 255-257.

Siegel, G., Albers, R., Brady, S. and Price, D. (2006). Basic Neurochemistry: Molecular, Cellular and Medical Aspects. (7th ed.). London: Elsevier Academic Press.

Wolf, B. and Green, D. (2002). Apoptosis: Letting slip the dogs of war. Current Biology, 12, R177-R179.

Yang, Y., Geldmacher, D. and Herrup, K. (2001). DNA replication precedes neuronal cell death in Alzheimer’s disease. Journal of Neuroscience, 21, 2661-2668.


More to come later, I promise!
 
Skeeve
I had forgotten how easy it was for solidsquid to give me a headache. Wink
"The world is my country, and do good is my religion." - Thomas Paine
 
seeker
I see how this describes a mechanism that would contribute to some diseases but is this a symptom of the disease or a cause of the disease
 
Hypatia
Since my husband and I take care of his 92 year old mother, who has Alzheimer's disease, I'm somewhat familiar with amyloid peptides, and maybe another thing or two from the article (doesn't mean I understand it well though), but otherwise I'm sharing in Skeeve's headache.

But I'll try to keep up, because it's interesting none the less.

 
Solidsquid
seeker wrote:
I see how this describes a mechanism that would contribute to some diseases but is this a symptom of the disease or a cause of the disease


That's one of the questions that's being attempted to be answered - is the ectopic cell cycling a consequence of the disease or a contributor? Some lean toward it being a contributor to the disease and others think it may be a consequence. Only further research may be able to answer that question and give us 50 more to answer. Such is the nature of science.
Edited by Solidsquid on 08/18/2008 14:14
 
seeker
That's kind of what I thought, we can see the process but really don't know what stage of the process we are seeing.
 
Hypatia
Solidsquid wrote:
seeker wrote:
I see how this describes a mechanism that would contribute to some diseases but is this a symptom of the disease or a cause of the disease


That's one of the questions that's being attempted to be answered - is the ectopic cell cycling a consequence of the disease or a contributor? Some lean toward it being a contributor to the disease and others think it may be a consequence. Only further research may be able to answer that question and give us 50 more to answer. Such is the nature of science.


Oy. Ain't that the truth. We've come so far, yet we're still so far away.
 
Solidsquid
Some more for everyone's reading pleasure:

How do researchers determine if a region of tissue is specified to become a particular cell type? Describe 3 different approaches.


Researchers utilize several methods for determining if tissue will be a specific cell type. One way researchers can determine what a tissue is fated to become is through the use of cell cultures. A progenitor cell is placed in isolation in a culture dish and different signal molecules are utilized to determine how they influence the fate of that progenitor cell (Sanes et al., 2006). Mouse embryonic stem cells (ES) have been utilized in cultures to examine differentiations through this method. As an example, Watt (1991) describes using mouse ES to examine the
 
Solidsquid
Tourette
Edited by Solidsquid on 10/14/2008 03:49
 
Jump to Forum: