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  #1  
Old 10-03-2011
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Question Pathology

A biopsy of a brain tumor from a 42-year-old man reveals a glial neoplasm consisting of atypical astrocytes with scattered mitoses. Besides mitotic activity, which of the following markers can provide information about the neoplasm's proliferative activity?
A. bcl-2
B. Glial fibrillary acidic protein (GFAP)
C. Ki-67
D. p53
E. Ubiquitin
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Old 10-03-2011
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I think the answer is B
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Old 10-04-2011
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C. Ki- 67. . . .
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Old 10-04-2011
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D. p53 hard q waitinf for the answer
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Old 10-04-2011
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Default C.

Quote:
Originally Posted by l2sweedan View Post
A biopsy of a brain tumor from a 42-year-old man reveals a glial neoplasm consisting of atypical astrocytes with scattered mitoses. Besides mitotic activity, which of the following markers can provide information about the neoplasm's proliferative activity?
A. bcl-2
B. Glial fibrillary acidic protein (GFAP)
C. Ki-67
D. p53
E. Ubiquitin
Ki-67...........
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Old 10-04-2011
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don t know the answer....i dont think is A or D..waiting for the answer
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Old 10-04-2011
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K-67 marker of proliferative activity, might be used for any kind of tumor or highly proliferating cells (regeneration)
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Old 10-04-2011
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The correct answer is C. Ki-67 is a nuclear factor (of uncertain function) whose expression correlates with neoplastic replicative activity. Its expression can be visualized by immunostaining of formalin-fixed, paraffin-embedded sections. Ki-67 labeling correlates with a neoplasm's rate of growth and, therefore, with prognosis.
The bcl-2 gene (choice A) suppresses apoptosis by different mechanisms. Its abnormal activation is involved in the pathogenesis of low-grade lymphomas but not astrocytomas.
GFAP (choice B) is an intermediate cytoskeletal filament (analogue of keratin and vimentin) expressed exclusively by certain types of glial cells, e.g., astrocytes and ependymal cells. Immunohistochemistry for GFAP is used diagnostically to confirm an astrocytic origin of a neoplasm, but gives no information about mitotic or proliferative rate.
The gene p53 (choice D) encodes a protein that blocks the cell cycle when damage to DNA occurs. If the damage is successfully repaired, p53 allows the cell cycle to resume; if not, p53 induces apoptosis, thus eliminating dangerous DNA mutations. Mutations of p53 have been found in the great majority of human neoplasms, including gliomas. However, its expression gives no information concerning neoplastic replicative activity.
Ubiquitin (choice E) is a low-molecular-weight heat-shock protein. Its function is to tag aberrant proteins for degradation. It is present in many abnormal intraneuronal inclusions associated with neurodegenerative disorders, such as Lewy bodies, Pick bodies, and neurofibrillary tangles. It has no relationship with mitotic activity or growth rate.
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