medsci 203 #1 Flashcards
(75 cards)
1
Q
Pathology
A
Medical science and practice concerned with all aspects of disease.
Pathology is an important discipline or acts as a critical bridge between basic science and clinical medicine.
2
Q
Morbid anatomy
A
Post-mortem macroscopic examination of disease. Benn practised since Classical Greek times.
1600s - Vesalius.
Observational science.
3
Q
Cellular and histopathology
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- Developed from the discoveries of Louis Pasteur (studied the effects of microorganism) and Rudolf Virchow (recognised that the cell is the basic living unit of disease).
4
Q
Molecular pathology
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Describes disease processes in terms of biochemical and molecular biological processes.
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Q
Anatomical pathology
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Macroscopic and microscopic study of tissue. Observational science.
6
Q
General pathology
A
Mechanisms of disease. Investigation of processes underlying disease conditions. Experimental science.
The pathogenesis of a disease is the mechanisms of its development.
7
Q
Aetiology
A
Causes
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Q
Cyto-
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relating to cells. E.g. cytotoxicity
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Q
Dys-
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Disordered. E.g. Dysplasia.
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Q
Hyper-
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An excess over normal. e.g. Hyperplasia
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Q
Hypo-
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A deficiency below normal. E.g. Hypothyroidism.
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Q
Leuko-
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White E.g. leukocyte.
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Q
Meta-
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A change of one state to another. E.g. Metaplasia.
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Q
Neo-
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New. E.g. neoplasia.
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Q
-aemia
A
relating to the blood. E..g Anaemia.
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Q
-cytosis
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An increased number of cells. E.g. Leukocytosis.
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-itis
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An inflammatory process. E.g. Appendicitis
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Q
-oid
A
having a resemblance to something. E.g. Epithelioid.
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Q
-oma
A
a growth. E..g atheroma, lymphoma.
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Q
-opathy
A
a diseased state. E.g. aden-patchy.
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-osis
A
a state or condition. E.g. acidosis.
22
Q
-penia
A
a lack of something. E.g. lymphopenia.
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Q
-plasia
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a disorder of growth. E.g. anaplasia, metaplasia.
24
Q
Crohn’s disease (CD)
A
First appears in adolescence or young adults. Occurs mainly at the end of the SI (Ileum) but can occur anywhere in the gut.
25
Affected areas of CD
are inflamed, red, swelling, pain, leukocyte infiltration.
| - Epithelial lining ulcerates
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Colon wall in CD.
may undergo excessive damage or fibrotic thinking.
Lumen narrows with obstruction (stenosed)
- Cracks/fissures develop through the bowel wall and drain into pus-filled cavities (abscesses) or form channels (fistulas) into nearby loops of bowel.
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Immune system during CD
Immune system is activated with aggregations of lymphocyte (follicles) and macrophages (granulomas). and enlarged lymph nodes.
Probability of developing cancer (neoplastic disease) is increased.
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Multiple etiological factors have been implicated in CD
- Family history suggest a genetic contribution. 30% Caucasians with CD have NOD2 gene mutated.
- Environmental factors. Incidence increase last 40 years. Diet, NSAIDs, tobacco, increased hygiene.
- Microbial factors. E.g. pathogenic infections as triggers.
- Uncontrolled immune response to commensal bacteria damage the bowel. E..g overactive TH1 cells which secrete TNF or under-active Treg cells.
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NOD2 protein
Pattern recognition receptor for bacterial products. May be needed for autophagic elimination of intracellular bacteria and for the antimicrobial activity of Paneth cells.
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Suggested outline of the pathogenesis of CD
- Environmental trigger may damage the mucosa.
- Damage (with bacterial invasions of submucosa) induces an inflammatory repose and healing.
- People with a genetic deficiency in innate immunity or barrier function may be unable to repair the damage or eliminate the microbes from the submucosa (+ lifestyle/environmental).
- Uncontrolled T cell responses may develop against commensal bacteria and ultimately damage the colon wall.
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Investigation of the causes of disease (etiology)
and the mechanism of disease (pathogenesis) resulting in the signs and symptoms (clinical significance).
- Environmental factors.
- Genetic factors.
- Cellular and molecular processes in cells and tissues.
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When studying disease or illness there are 4 aspects to consider :
- etiology
- pathogenesis
- structural changes in cells or tissues.
- Clinical manifestations
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In general, cells, tissues and organ systems respond or react to initial etiologic events in following ways :
- degeneration and atrophy
- apoptosis and necrosis.
- Inflammation.
- Regeneration, hyperplasia and hypertrophy.
- Dysplasia and neoplasia.
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The tools of pathology
- Molecular strategy
- Morphology
- Immunologic
- Microbiologic
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Analysis of cell, tissue biopsy
Cytology and morphology.
- Types of cell present, cytology of the cells, architecture of tissue.
Microbiology
- Culture cells, tissues or swaps/scrapings from the tissue.
Immunology
- Look for antigen expression
Molecular studies
- Chromosome analysis, DNA and RNA analysis e.g. pattern of gene expression in tumours.
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Molecular pathology
The study and diagnosis of disease through examination of molecules within organs, tissues or body fluids.
LAB - understand gene functions and advance disease treatments.
Clinic - Improved diagnosis to allow use of preventative treatment.
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The Human Genome
The DNA contained within our cells, consisting of all genes and regulatory sequences.
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Analyse DNA
PCR (polymerase chain reaction). Selectively amplifies known regions of DNA using enzymatic synthesis. Cyclical process of heating and cooling using thermostable Taq polymerase in combination with DNA primers to denature, anneal and copy DNA.
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Advantages of using PCR amplification
- Substitute for cloning.
- Targeted. Excellent for amplifying very specific sequences of interest from small amounts of material.
- It can selectively detect DNA sequences from a mixture.
- Can be used on highly degradable DNA samples.
- Very cheap.
40
Gel electrophoresis
Visual analysis of PCR products. Separated DNA fragments by size and charge.
Dna loaded gels are stained with a DNA-binding dye and visualised under UV light, allowing sizing and quantitation of the PCR product based on intensity.
- By simple sizing it is possible to look for DNA deletions and insertions.
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Read - DNA sequencing
Take a template DNA strand and incorporate labeled dNTPs by a further PCR-type reaction that can be 'read' when incorporated into the growing DNA.
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Automation
Sanger sequencing. fluorescence instead of radioactive dNTPs were used.
Smaller quantities of DNA input were able to be analysed.
To identify single point mutations or small insertions/deletions.
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Genetics ---> Genomics
Next generation sequencing (NGS). Genomics = analysis of the whole genome.
- Improvement in sequencing technology and a reference human genome.
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Advantages of NGS
Can look for unknowns. Does not rely on PCR amplification of a specific region of DNA. So can sequence all of the DNA present in a sample.
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Disadvantages of NGS
Generate big data that requires massive computational power.
Identify the disease causing mutation in the 2.3 billion DNA letters.
May also find potential mutations that relate to later-onset disease. --> ethical dilemma of whether to return those incidental findings to an individual.
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Analyse RNA
By looking at the RNA you can visualise the effects of a DNA mutation.
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Reverse transcription (RT)
Enzymatic step that converts RNA into copy DNA (cDNA) and amplifies it.
RT-PCR converts all RNA in a sample into cDNA then amplifies a specific gene region in the PCR step. (Able to count the gene transcripts/RNA or gene expression).
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Hybridisation
Allows specific detection of sequences of interest in a complex sample mixture (ignores background). Formation of double stranded DNA between 2 strands of complementary nucleotide sequence. Often one genomic DNA and the other synthetic DNA probe designed to specific sequence.
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Methods of hybridisation
```
Dot Blot
Southern blot (DNA)
Fluorescent in situ hybridisation (FISH)
Microarrays
Array Comparative Genomic Hybridisation (aCGH).
```
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Microarrays
Enables the analysis of thousands of genes or RNAs of interest in one experiment.
Can also be used to detect SNPs (single nucleotide polymorphisms).
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Array CGH
Another array method used to hunt for DNA copy number changes. (amplification or deletion of regions of DNA).
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Analyse Protein
Most protein analyse methods rely on specific antibodies being generated in animal donors to detect the protein of interest.
Western Blot, Immunohistochemistry, immunoassay
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Western Blot
Immunoblotting. Analysis of a homogenised protein lysate separated by size by gel electrophoresis.
Good to confirm presence, abundance and size of a protein.
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Immunohistochemistry
Analysis of protein in a tissue section itself. Good to confirm presence, abundance and cellular localisation.
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Immunoassay
E.g. ELISA = enzyme linked immunosorbent assay. Good to detect protein presence and quantity often in body fluids.
56
Suggested outline of the pathogenesis of CD
- an environmental trigger may damage the mucosa.
- Damage (with bacterial invasion of the submucosa) induces an inflammatory and healing response.
- People with a genetic deficiency in innate immunity and/or barrier function may be unable to repair the damage or eliminate microbes from the submucosa (especially in context of environmental factors) --> chronic inflammation due to uncontrolled T cell responses against commensal bacteria --> damage of colon wall.
57
When the NOD2 gene is mutated
cells in the lining of the gut don't sense microbes as they should thus microbial interaction becomes more threatening.
58
Molecular pathology
is the study and diagnosis of diseases through examination of molecules within organs, tissues or body fluids.
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The Disease Process
When studying disease or illness there are 4 aspects to consider :
- Etiology
- Pathogenesis.
- Structural changes in the cells or tissues.
- Clinical manifestations.
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Etiology or Cause
There are two major classes of etiologic factors.
- Intrinsic or genetic (inherited).
- Acquired/environmental (Infectious, toxic, traumatic, nutritional, immunological etc).
but now recognise a significant overlap and interaction of genetic and environmental factors e.g. ischaemic heart disease, diabetes, asthma.
61
Penetrance
The extent to which a particular gene or set of genes is expressed in the phenotypes of individuals carrying it.
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Pathogenesis
although the initial etiological factor may be recognised this refers to the sequence of changes which occurs in the cells and tissues following the initial genetic or environmental events (insult or injury).
63
In general cells, tissues and organ systems respond or react to initial etiologic events in these ways :
- Degeneration, atrophy.
- Necrosis, apoptosis.
- Inflammation.
- Regeneration, Hyperplasia, hypertrophy.
- Neoplasia and dysplasia.
64
Morphologic changes
Refers to the structural changes (gross and microscopic) seen in the cells, tissues and organs. This refers to the basis of diagnostic pathology which provides clinicians with a diagnosis and now increasingly prognostic and therapeutic information.
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Clinical manifestations/ Functional Derangement
The morphological changes in the tissues and organs will lead to altered function of that organ, resulting in clinical manifestations of the disease process. This may be be :
- Symptoms.
- Clinical signs.
- Laboratory abnormalities and radiological changes.
66
Clinical pathology aids the clinician in
- Diagnosis.
- prognosis
- Monitoring response
- screening strategies.
- Preventive strategies.
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The tools of pathology
- Molecular
- Microbiologic.
- Morphology
- Immunologic.
68
Investigation of a mass/abnormal tissue
- Fine needle aspiration
- Exfoliative cytology e.g. cervical smear, brushings from a tumour.
- Tissue biopsy (core, excisional or incisional biopsy).
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Analysis of cells/tissue biopsy
Cytology and morphology
- Types of cells present, cytology of cells, architecture of the tissue.
Microbiology
- Culture cells, tissues or swaps/scrapings from the tissue.
Immunology
- Look for antigen expression.
Molecular studies
- Chromosome analysis, DNA and RNA analysis e.g. pattern of gene expression in tumours.
Using these strategies and tool, pathology attempt to explain the basis of disease, and provide a rational framework for clinical care and therapy.
70
Clinical significance HER-2 amplification.
HER-2 is an proto-oncogene which encodes for an epidermal growth factor receptor in mammary cells.
- HER-2 protein is over expressed in 25-30% of breast cancer patients and in 90% of these cases it is due to amplification = extra copies of the HER-2 gene.
- HER-2 is a target for the antibody, herceptin.
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Proto-oncogene
is a normal that is present in the DNA of all of us but can be damaged (mutated) to behave abnormally (oncology).
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Future challenges
Personalised cancer medicine.
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The human genome
the DNA contained within our cells, consisting of all the genes and regulatory sequences.
Larger nuclear genome - 3.2 billion nucleotides.
Smaller mitochondria genome - 16.5 thousand nucleotides
in each cell.
74
Advantages of using PCR amplification
1. Substitute for 'cloning'.
2. It is targeted - excellent for amplifying very specific sequences of interest from small amount of of material e.g. forensics.
3. Can selectively detect DNA sequences from a mixture. E.g. detect a virus in our blood where the DNA present in a combination of ourselves and environmental bacteria/virus.
4. Can be used on highly degraded DNA samples.
5. Cheap and very accessible.
75
Genomics
Using DNA sequencing and bioinformatics to assemble and understand the structure and function of the genome.
