Molecular Histopathology Flashcards
1
Q
What are histological techniques?
A
- preparation of biological tissue for microscopic examination in a state as close as possible to which it existed in life
2
Q
What are the 4 types of tissue?
A
- epithelial
- connective
- muscle
- nervous
3
Q
Describe Epithelial Tissue
A
- tightly packed cells
- conver the outside of the body & lines organs & cavities of body
- attached to basement membrane
4
Q
Describe connective tissue
A
- provides structural support to other tisuse & organs
- mediates the supply of nutrients & removal of waste
- connective tissue cells produce extracellular matrix
5
Q
Describe muscle tissue
A
- types = skeletal, cardiac & smooth
- generate motile forces –> consequence of proteins actin & myosin interacting
6
Q
Describe Nervous tissue
A
- aid precise communication
- comprised of specialised cells - neurones
- 2 groups = CNS & SNS
- Axons = relatively long connecting branch or process
- Dendrites = branched ending of neurone forming connections/synapses with other neurones
7
Q
Describe Haematoxylin & Eosin staining
A
- long history of use - Mayer 1904
- primary diagnostic technqiue in histopathology laboratory
- primary technique for the evaluation of morphology
- widely used - 2.5-3 million slides per day
8
Q
Describe Haemotoxylin
A
- purple/blue stain (basophilic)
- Stains acidic materials
- stains nucelar contents
9
Q
Describe Eosin
A
- pink stain (eosinophilic)
- stains most cytoplasmic contents
10
Q
Describe Immunohistochemistry (IHC)
A
- IHC uses antibodies to detect the location of proteins & other antigens in tissue sections
- antibodies are highly specific
- antibody-antigen interaction is then viewed using either a coloured enzyme substrate or a fluorescent dye
11
Q
Describe ICH antibody application
A
- incubation with primary antibody -> floating immersion & on slides on a stage in humid chamber
- conditions should include consideration that they degrade
- use the lowest effective dilution which need to be determined empirically
12
Q
Describe the Avidin-Biotin-Complex (IHC)
A
- ABC method - 3 steps
1. bind 1 to Ab to Ag
2. bind to biotinylated 2 Ab to 1 Ab
3. bind avidin-biotin-peroxidase complex to 2 Ab
13
Q
Describe Direct Immunofluorescence (IHC)
A
- 1 step
- Ab is labelled with fluorescent tag
- technique is fast
- low sensitvity due to lack of signal amplification
14
Q
Describe Indirect Immunofluorescence (ICH)
A
- bind 1 Ab to Ag
- bind fluorescent labeled 2 Ab to 1 Ab
- sensitive - signal amplicification
- use one 2 Ab for many unlabeled Ab
15
Q
Define Tumour Markers
A
- substance present in the tumour, produced by the tumour or organism as a response to the presence of the tumour
- provides info about biological characteristics of the tumour
16
Q
Define Qualitative determination of tumour markers
A
- histopathological, in the tumour tissue
17
Q
Define Quantitative determination of tumour markers
A
- in the serum or biological fluid, dynamic follow up
18
Q
Define soluble makers
A
- classical tumour markers, various chemical substances
19
Q
Define circulating cellular elements
A
- circulating tumour cells, circulating endothelial cells & their precursors
20
Q
Define Genetic abnormalities
A
- detection of mutations in oncogenes & tumour suppressor genes, protein products of oncogenes, further changes
21
Q
What are some chemical characteristics of TU markers?
A
- enzymes = PSA, NSE, TK
- Immunoglobulins = IgG, IgM, IgA
- hormones = growth hormone, ACTH
- cytokeratines
- glycoproteins,glycolipids & saccharides
22
Q
Describe an Ideal TU marker
A
- high specificity = not present in other diseases -non tumours & in healthy subjects
- high sensitivity= detectable at the beginning of the disease
- optimal positive & negative predictive value
- organ specific
doesn’t exist so far
23
Q
Describe how effective CEA is as a tumour marker for colorectal cancer
A
- 95% specificity = 5% of healthy subjects are falsely regarded as patients with tumours
- 70% sensitvity = does not detect 30% of patients with tumours
24
Q
Give some examples oncogenes & anti-oncogenes
A
- p53 - regulation of cell cycle
- BRCA 1 & BRCA 2 - repair of DNA defects
- RB1 - Regulation of cell cycle (retinoblastoma)
25
Describe Post-translational modifications (PTMs)
- many proteins undergo chemical modifications at certain amino acid residues
- modifications are essential for normal functioning
26
What are some examples of post-translational modifications ?
- phosphorylation
- glycosylation
- acylation
- hydroxylation
- alkylation & methylation
27
Define phosphorylation
process by which a phosphate group is attached to cartain amino acid side chains in the protein
- most commonly = serine, threonine & tyrosine
28
Describe Glycosylation
- attachment of sugar moieties to nitrogen or oxygen atoms present in the side chains of amino acids like aspargine, serine or threonine
29
Describe Acylation
the process by which an acyl group is linked to the side chain of amino acids like aspargine, gluatamine or lysine
30
Describe Alkylation
addition of alkyl groups, most commonly a methyl group to amino acids such as lysine or arginine
31
Describe Hydroxylation
- most often found on proline & lysine residues which make up the collagen tissue
- enables cross-linking & therefore strengthening of muscle fibres
32
Give some examples of potential new tumour markers
- apoptosis
-angiogenesis
-signal transduction
33
Describe chronic myeloid leukaemia
- cancer of bone marrow stem cells
- CML = clonal myeloproliferative neoplasm
- three phases ; chronic, accelerated, blast
- most pateints are diagnosed in chronic phase- often without symptoms
- untreated all pateints progress to accelerated/blast phase withing 3-5 years
34
Describe what causes CML?
- fusion of.2 genes = BCR (chromosome 22) and ABL1 (on chromosome 9) resulting in BCR-ABL1 fusion gene
- final result = abnormal chromosome 22 called Philadelphia (Ph) chromosome
- final product = BCR-ABL1 fusion protein = a dysregulated tyrosine kinase
35
What is the chronic phase of chronic myeloid leukemia a direct result of?
- activity of BCR-ABL1 which allows;
1. uncontrolled proliferation of transformed cells
2. discordant maturation
3. escape from apoptosis
4. altered interaction with the cellular matrix
36
Describe Fluorescence in situ hybridisation (FISH)
- permits detection of selected acquired genetic changes in dividing & nondividing cells
- FISH studies are used to investigate the origin & progression of hematological malignancies
37
Describe APC gene/ Beta catenine pathway
- develop thousands of adenomatous polyps
- APC protein bind & regulates the degradation of b catenine levels in cytoplasm
- absences of APC = b catenine levels increase = up regulate cell proliferation
- APC is a negative regulator of b catenine
38
What is the signature colorectal cancer progression?
- Normal epithelium
- hyper-proliferative epithelium
- early adenoma
- inter-mediate adenoma
- late adenoma
- carcinoma
- metastasis
