patho sheet by halah obeidat(seconed lecture of 25/10/2010)

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patho sheet by halah obeidat(seconed lecture of 25/10/2010)

Post by halah_obeidat on 25/10/2010, 11:52 pm

بسم الله الرحمن الرحيم

note: this is the lec.we got in 25/10 (9:00-10:00) after the additional lec. at 8:00
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Slide NO. 59 : invasion and metastasis(metastasis is the most important) are hallmarks of malignant tumour
Detachment :Loosening the tumour cells from each other
The glues that are found between the epithelial cells are called E-cadherin loss of the E-cadherin is not a spontaneous process its only by mutation to their gene
The break down of :Extra cellular matrix, Basement membrane, interstitial matrix
Slide 62: in order for the cell to migrate and to invade, attachment between the tumour cells and the degraded extra cellular matrix must occur
And that is established by : degradation of the extra cellular matrix causes revealing of sites that will have high affinity to certain receptors on the tumour cell
Their migration is by facilitated by chemotactic attractants (cytokines) the tumour cells themselves will secrete a chemoattractin called autocrine motility factor and Insulin like factors 1 and 2
-Metastasis: tumour cell must enter the blood vessel to cause mets
-the same process that happened to invade the tissues happen ( extracellular matrix) but with invasion of a capillary bed :Secretion of Metalloproteinase to degrade the basement membrane of the blood vessel Entrance of the blood vessel Some of the tumour cells might be killed by the host defence mechanism but to escape they might cover themselves with platelets (tumour embolus) secretion of metalloproteinase again to degrade the basement membrane of the blood vessel (from the inside ) and the extracellular matrix ....mets has occurred in a site remote from the actual tumour
-tumour doesn’t affect the blood cells they will try to destroy the tumour only if the tumour reaches the bones marrow
63: site of metastasis
carcinoma favour the lymphatic sarcoma favour the haematogenous
-Tumour cells behave as they like they don’t always follow the natural pathways of the mets like lung to adrenal gland not the natural drainage pathway
The explanation : chemokines and adhesion molecules receptors will be expressed on tumour cell and their ligands will be found on the blood vessels of the ‘’abnormal, unordinary ’’ mets sites therefore attraction and binding will occur between them
-Some sites in our body will not afford a micro environment for metastasis like the skeletal muscles
64:etiology of cancer
- 5-10% inherited the rest are caused by Environmental factors (which are the most important factor) that will cause somatic mutation which will affect the growth promotion genes, tumour suppresser genes, the apoptosis genes ,DNA repair genes
-A single mutation in one of the mentioned genes does not cause a malignant transformation more than one mutation is needed
65: direct and indirect acting agents
-Direct: Active by themselves no need to metabolic conversion
-Not every exposure to the chemical causes cancer formation
-The conversion of the indirect carcinogen most likely by the enzyme p450 mixed in the liver
-type of bladder cancer: transitional cell carcinoma
-afelatoxin b1: more in the Far East and Africa because of wrong storage of nuts and grains
-In the past patients with tenia (the fungal infection of the head) were given therapeutic irradiation or as a cure for Hodgkin lymphoma
Pyramdine dimmer: cross linkage between pyramidine dimmers
Hereditary form of cancer: autosomal recessive deficiency of DNA repair mechanism ’’xeroderma pigmentosum’’ no repair of the dimmers therefore cancers will occur like squamous cell carcinoma basal cell carcinoma melanoma.

Done by : halah obeidat 25/10/2010

عدد المساهمات : 3
النشاط : 0
تاريخ التسجيل : 2009-09-06

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