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Flashcards in case unit 1 - cholera Deck (46):
1

which averages should you use for quantitative data

median
mean

2

why is the mode not useful for quantitative data

there might be more than one mode
each value in the study might only appear once
mode could be a high or low number (far from middle)

3

what methods do you use to quantify variation?

sd
iqr
range

4

benefits of case report study design

can identify new trends/diseases
helps detect new drug side effects
identifies rare manifestations of a disease

5

case report study

reports a new case of newly identified symptoms or outcomes
observation of symptoms, diagnosis and treatment of the individual case
presents hypothesis to be confirmed by another study type

6

types of observational study

case report
case control
cohort

7

limitations of case report study

may not be able to generalise the individual cases
report not based on systematic studies
other possible explanations for outcomes
report only focuses on rare event, may be misleading

8

case control study

'retrospective' - disease has already occurred
compares patients with disease to those without
evaluates relationships between risk factors and disease
estimates odds

9

benefits of case control study

good for studying rare diseases
takes little time as disease has already occurred
multiple risk factors can be studied at the same time
risk factor-disease associations can be established

10

limitations of case control

problems with data quality and data relies on memory
recall bias as people remember worse things
hard to find suitable control group

11

cohort study

evaluations of causative risk factors determined after following cohort populations during their disease
measurements taken of outcomes

12

benefits of cohort study

subjects are matched which limits influence of confounding variables
standardisation of criteria/outcomes
easier and cheaper than rct

13

limitations of cohort study

difficult to identify cohorts due to confounding variables
no randomisation
blinding of subjects is difficult
takes time for outcome of interest to occur

14

randomised control study

subjects randomly assigned to control or intervention group
only variable studied is the expected difference between the groups

15

benefits of rct

no population bias due to randomisation
easier to mask/blind subjects
statistical analysis using known methods easy
clearly identified populations

16

limitations of rct

expensive
time-consuming
volunteering populations not representative of entire population
causation of disease not revealed

17

practice guidelines

produced by panel of experts
guidelines on prevention/treatment/diagnosis/prognosis of disease
informs health care professionals

18

systematic review

combines and summarises all information from previous studies on one health topic or question

19

meta-analysis

statistical method of combining results from different studies to increase statistical power

20

what are kochs postulates used for?

establishing a causative relationship between microbe and disease

21

what do koch's postulates require

that the pathogen is present in all cases of the disease
that the pathogen can be isolated from the host and grown in pure culture
the pathogen grown in culture can cause the same disease when inoculated into a healthy, susceptible lab animal
that pathogen can then be re-isolated and be the same as the originally isolated pathogen

22

aetiology

study of the manner of causation of the disease

23

kuhn

paradigm shift

24

what is meant by the term paradigm shift

a fundamental change in the basic concepts and experimental practices of a scientific disciplicne

25

when does a paradigm shift occur

when there are enough significant anomalies that cannot be explained by the current paradigm

26

why can pcr be used to detect viral dna in human tissue samples

viral dna sequences will be different to any human dna sequences

27

outline process of pcr for viral dna

identify specifc viral dna sequence
make forward and reverse primers
mix sample and primers and heat to 96 to denature
cool to 60 to allow complementary base pairing - annealing
heat to 72 - optimum for dna polymerase- extension

28

how do you separate dna after pcr

using agarose gel
separated on a size basis

29

uses of qPCR

quantifies amount of a specific sequence of dna
quantifies expression levels of mRNA

30

why do we need reverse transcriptase for qPCR

pcr only works on dna not rna

31

what does reverse transcriptase do

converts mRNA to cDNA

32

how is cDNA produced by PCR measured

by a dye that fluoresces when bound to DNA

33

delta Ct

the change in expression in control sample

34

uses of next generation sequencing

determining the DNA sequence of large numbers of different DNA molecules
genome sequencing
cDNA sequencing

35

illumina next gen seq method

fragment the genome of dna
each fragment gets own area of machine
dna amplified into clusters
add coloured labelled nucleotides in rounds

36

use of computer in next gen seq

rebuilds dna fragments
looks for overlapping sequences to assemble the gene

37

deep sequencing

multiple sequencing to reduce error

38

exome sequencing

only sequence part of the genome

39

what is a variable

a set of characteristics (data values)
e.g. gender/systolic blood pressure

40

types of variable

categorical
quantitative

41

types of categorical variable

nominal - labelled, unordered
ordinal - ranked

42

what type of variable is 'disease severity'

ordinal

43

relative frequency

way of describing categorical data
proportion or percentage

44

bar chart

graphical description of categorical data

45

ways to describe quantitative data

average
variation
symmetry

46

relative quantification (RQ)

how many fold increase in expression
ussing delta ct on pcr cycle graph