Lecture Content Flashcards
An article that describes and interprets an individual case, often written in the form of a detailed story
Case study
When are case studies most appropriate?
Unique cases that cannot be explained by known diseases or syndromes
Cases that show unexpected events/ may yield new or useful information
Considered lowest level of evidence but first line where new issues/ evidence arises
Case study
What are he advantages of a case study?
Can help identification of new trends/ diseases
Can help detect a new drug side effects and potential uses
A way of sharing lessons learned (educational)
Identifies rare manifestations of a disease
What are the disadvantages of a case study?
Causes may not be generalisable
Not based on systematic studies
Causes or associations may have other explanations
A study that compares patients who have a disease or outcome of interest (cases) with patients who do not have the disease (control)
It looks retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between risk factor and disease.
Case control study
Is a case control study observational or interventional?
Observational
What is the goal of a case control study?
Determine effect of exposure to risk factor in both groups
What are the advantages of a case control study?
Good for studying rare conditions/ diseases
Less time required to conduct study as disease has already occurred
Allows you to look at multiple risk factors simultaneously
What are the disadvantages of a case control study?
More problems with data quality as rely on patient memory (recall bias)
Not good for evaluating diagnostic tests
Difficult to find suitable control group
One or more samples, known as cohorts are followed prospectively and evaluations are made with respect to disease or outcome to determine which participants exposure to which risk factors are associated
Cohort study
What are the advantages of a cohort study?
Subjects in cohorts can be matched limiting confounding variables
Standardisation of criteria/ outcome possible
Easier and cheaper than RCT
What are the disadvantages of a cohort study?
Cohorts difficult to identify due to confounding variables
No randomisation - imbalance in patient characteristics could exist
Blinding is difficult
Outcome of interest could take time to occur
Randomly assigns participants into experimental and control groups. Only expected difference between control and experimental group = outcome variable being studied (in theory)
Randomised control trial (RCT)
What are the advantages of a randomised control trial?
Good randomisation removes population bias
Easier to blind than observational studies
Results can be statistically analysed
Populations of participating individuals can be clearly identified
What are the disadvantages of a randomised control trial?
Expensive- time and money
Volunteer biases- population that participate may not be representative of the whole population
Doesn’t give causation
Can’t follow up with treatment
What are Koch’s postulates designed to establish?
Causative relationship between microbe and disease
Name koch’s postulates
- ) the microorganism must be found in abundance in all organisms suffering from the disease, but not in healthy organisms
- ) the microorganism must be isolated from a disease organism and grown in pure culture
- ) the cultured microorganism should cause disease when introduced into healthy organism
- ) the microorganism must be reisolated from the inoculated diseased experimental host and identified as being identical to the original specific causative agent
Define paradigm shift
A fundamental change in the basic concepts and experimental practices of a scientific discipline
Evidence builds up that contradicts the prevailing theory and the theory undergoes crisis
A new paradigm is established, and scientists work ‘normally’ within those paradigms
What does qPCR tell you?
How much specific mRNA there will be in your sample
What does the Ct measure?
Cycle number at which fluorescence starts increasing
What is mRNA converted into in qPCR, and via what enzyme?
mRNA –> cDNA via reverse transcriptase
What does a lower Ct measure indicate?
Lower Ct = signal appears quicker = more mRNA present in the sample
How do you calculate the fold increase in expression in qPCR?
2- delta delta Ct
What is the purpose of PCR?
Making many copies of a piece of DNA
Can be used to detect presence or absence of viral DNA
What is the rough protocol of a PCR cycle?
Heat to 96 (denature)
Cool to 60 (primers anneal)
Heat to 73 (taq polymerase synthesises new DNA)
Repeat
