Clinical Sciences and Statistics Flashcards
LVEF = ?
(SV / EDV) x 100
Left Ventricular ejection fraction = (Stroke volume/ End diastolic volume) x 100
Stroke volume (end diastolic - end systolic)
Standard error of the mean = ?
Standard error of the mean = standard deviation / square root (number of patients)
The power of a study is…
The power of a study is the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference
where is phosphate reabsorbed?
proxmial tubule
What electrolytes are absorbed in the distal tubule (3)
sodium
potassium
calcium
Relative risk reduction = ?
Relative risk reduction = (EER - CER) / CER
EER = experimental event rate CER = control event rate
Most immunoglobulin and antibodies are produced by…
plasma cells
Blood smear result for DIC
Schistocytes
p53 plays a crucial role in the cell cycle, it is responsible for…
Preventing entry into the S phase until DNA has been checked and repaired
Outline the 5 steps of atherosclerosis
- Endothelial dysfunction triggered by smoking, hypertension or hyperglycaemia.
- Pro-inflammatory, pro-oxidant, proliferative changes in the endothelium.
- Fatty infiltration of the subendothelial space by low-density lipoprotein (LDL).
- Macrophages phagocytose oxidised low-density lipoprotein.
- Smooth muscle proliferation and migration from the tunica media into the intima.
Peroxisome main function
Catabolism of long chain fatty acids (poly peptides)
Proteasome main function
degradation of protein molecules that have been tagged with ubiquitin
Ribosome main function
translation of RNA into proteins
Nucleolus main function
Ribosome production
Lysosome main function
breakdown of polysaccharides and proteins
Nucleus main function
DNA maintenance
RNA transcription
RNA splicing
Mitochondria main function
aerobic respiration
Golgi apparatus main function
- packages molecules that are destined for cell secretion
- adds mannose-6-phosphate to proteins for transport to lysosome
Smooth endoplasmic reticulum main function
steroid, lipid synthesis
example of cells with SER: adrenal cortex, hepatocytes, testes, ovaries
Rough endoplasmic reticulum
translation and folding of new proteins
manufacture of lysosomal enzymes
site of N-linked glycosylation
examples of cells with extensive RER include pancreatic cells, goblet cells, plasma cells
Interferon-γ main source and function
T helper 1 cells
activates macrophages
Tumour necrosis factor (TNF) main source and function
Macrophage
induce fever, neutrophil chemotaxis
Likelihood ratio for a positive test result = ?
sensitivity/ (1 - specificity)
Likelihood ratio for a negative test results =?
(1 - sensitivity)/ specificity
Type 1 hypersensitivity
mechanism
examples
IgE
anaphylaxis, atopy
Type 2 hypersensitivity
mechanism
examples (guess a few)
IgG/ IgM Autoimmune haemolytic anaemia • ITP • Goodpasture's syndrome • Pernicious anaemia • Acute haemolytic transfusion reactions • Rheumatic fever • Pemphigus vulgaris / bullous pemphigoid
Type 3 hypersensitivity
mechanism
examples
IgG, IgA - free antigen and antibody combine
• Serum sickness
• Systemic lupus erythematosus
• Post-streptococcal glomerulonephritis
• Extrinsic allergic alveolitis (especially acute phase)
Type 4 hypersensitivity
mechanism
examples
T cell mediated • Tuberculosis / tuberculin skin reaction • Graft versus host disease • Allergic contact dermatitis • Scabies • Extrinsic allergic alveolitis (especially chronic phase) • Multiple sclerosis • Guillain-Barre syndrome
Type 5 hypersensitivity
mechanism
examples
Antibodies bind to cell surfaces
Graves
Myasthenia gravis
Vitamin B3 (Niacin) deficiency - Pellagra Features (3)
diarrhoea
dermatitis
dementia
Antidiuretic hormone (ADH) is secreted from the [X]. It promotes water reabsorption in the [Y] of the kidneys by the insertion of [Z]. eg. Desmopressin
X - posterior pituitary gland
Y - collecting ducts
Z - aquaporin 2 channels
Number needed to treat = ?
NNT = 1/ ARR
ARR = absolute risk reduction
Absolute risk reduction =
control event rate - experiment event rate
Layers of the skin (5)
- Stratum corneum - Flat, dead, scale-like cells filled with keratin
Continually shed - Stratum lucidum - Clear layer - present in thick skin only
- Stratum granulosum - Cells form links with neighbours
- Stratum spinosum - Squamous cells begin keratin synthesis
Thickest layer of epidermis - Stratum germinativum - The basement membrane - single layer of columnar epithelial cells
Gives rise to keratinocytes
Contains melanocytes
Variance is a measure of the spread of scores away from the mean.
Variance = ?
Variance = square of standard deviation
6 stages of Mitosis
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
Mitosis steps 1 + 2
Prophase - Chromatin in the nucleus condenses
Prometaphase - Nuclear membrane breaks down allowing the microtubules to attach to the chromosomes
Mitosis steps 3 + 4
Metaphase - Chromosomes aligned at middle of cell
Anaphase - The paired chromosomes separate at the kinetochores and move to opposite sides of the cell
Mitosis steps 5 + 6
Telophase - Chromatids arrive at opposite poles of cell
Cytokinesis - Actin-myosin complex in the centre of the cell contacts resulting in it being ‘pinched’ into two daughter cells
P value is…
P value - is the probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true
Significance tests
Parametric (2)
Parametric tests (something that can be measured, usually normally distributed)
Student’s t-test - paired or unpaired*
Pearson’s product-moment coefficient - correlation
Significance test
Non-parametric (4)
Non-parametric tests:
- Mann-Whitney U test - compares ordinal, interval, or ratio scales of unpaired data
- Wilcoxon signed-rank test - compares two sets of observations on a single sample, e.g. a ‘before’ and ‘after’ test on the same population following an intervention
- Chi-squared test - used to compare proportions or percentages e.g. compares the percentage of patients who improved following two different interventions
- Spearman, Kendall rank - correlation
Acute tubular necrosis microscopy
granular, muddy-brown urinary casts
Clinical trials
Phase Goal Notes
I Determines pharmacokinetics and pharmacodynamics and side-effects prior to larger studies Conducted on healthy volunteers
II Assess efficacy + dosage Involves small number of patients affected by particular disease
May be subdivided into
IIa - assesses optimal dosing
IIb - assesses efficacy
III Assess effectiveness Typically involves 100-1000’s of people, often as part of a randomised controlled trial, comparing new treatment with established treatments
IV Postmarketing surveillance Monitors for long-term effectiveness and side-effects
CD cluster
Cluster of differentiation Function
CD1 MHC molecule that presents lipid molecules
CD2 Found on thymocytes, T cells, and some natural killer cells that acts as a ligand for CD58 and CD59 and is involved in signal transduction and cell adhesion
CD3 The signalling component of the T cell receptor (TCR) complex
CD4 Found on helper T cells.
Co-receptor for MHC class II
Used by HIV to enter T cells
CD5 Found in the majority of mantle cell lymphomas
CD8 Found on cytotoxic T cells.
Co-receptor for MHC class I
Found on a subset of myeloid dendritic cells
CD14 Cell surface marker for macrophages
CD15 Expressed on Reed-Sternberg cells (along with CD30)
CD16 Bind to the Fc portion of IgG antibodies
CD21 Receptor for Epstein-Barr virus
CD28 Interacts with B7 on antigen presenting cell as costimulation signal
CD45 Protein tyrosine phosphatase present on all leucocytes
CD56 Unique marker for natural killer cells
CD95 Acts as the FAS receptor, involved in apoptosis
standard error of the mean
Standard error of the mean = standard deviation / square root (number of patients)
Troponin T binds to…
Troponin T binds to tropomyosin, forming a troponin-tropomyosin complex
what bias is a particular problem in case-control studies
recall bias
Selection bias is…
Error in assigning individuals to groups leading to differences which may influence the outcome.
eg. sampling bias, volunteer bias, non-responder bias
Bias found in non-blinded trials. Observers subconsciously report data in a way that favours the expected outcome.
Expectation bias (Pygmalion effect)
Hawthorn effect describes…
Describes a group changing it’s behaviour due to the knowledge that it is being studied
X linked dominant conditions (3)
alports
retts
Vit D resistent rickets
Post-test probability = ?
Post-test probability = post test odds / (1 + post-test odds)
Cohort study usual outcome measure…
relative risk
Turner’s most common cardiac abnormality
bicuspid aortic valve
Cytokines - Main source + function
TNF a
IFN y
TNF a - from macrophage - induce fever, neutrophil chemotaxis
INF y - from Th1 cells - activate macrophage
ADH (diabetes insipidus) is from [X} and acts upon [Y]
X - hypothalamus (supraoptic nuclei)
Y - collecting ducts
Adrenal cortex mnemonic
Adrenal cortex mnemonic: GFR - ACD
Glomerulosa - Aldosterone (mineral corticoid)
Fasciculata - Cortisone (glucocorticoid)
Reticularis - DHEA (androgens)
Adrenaline acts via
G protein coupled receptors
Tay-Sachs
features
Developmental delay, Cherry red spot on macula, Nil hepato/ splenomegaly
Normally around 6 months old
Insulin binds to what receptor
Tyrosine kinase
C1q, C1rs, C2, C4 deficiency association
immune complexes - HSP, SLE
C3 Deficiency association
recurrent bacterial infections
C5 deficiency
Leiner disease, diarrhoea, dermatitis
C5-9 deficiency
Neisseria Meningitidis
Subunits of troponin bind to…
Trop C
Trop T
Trop I
C - Calcium
T - Tropomysin - forms Troponin-tropomysin complex
I - Actin
Homocystinuria inheritance pathophys features Ix Mx
autosomal recessive
P - deficiency of cystathionine beta synthase
Fx - Marfinoid, learning difficulty, downward dislocation of lens
Ix - cyanide-nitroprusside test
Mx - Vitamin B6 (Pyridoxine)
X-linked recessive conditions
female carriers -> 50% male effected; 50% female carrier; nil male-male transmission, females never effected
Muscular dystrophy, colour blindness, G6PD def, Haemophillia A, Nephrogenic DI, Fabrys… amongst others
What supplement aids iron absorption in the gut?
Vitamin C (ascorbic acid)
Case control outcome measure…
Odds ratio
cohort study outcome measure…
relative risk
HLA antigens encoded on which chromosome?
chromosome 6
dry beriberi is..
thiamine deficiency leading to peripheral neuropathy
wet beriberi is…
thiamine deficiency with heart failure
Riboflavin is required for…
Hydrogen-transfer chain in mitochondria and production of ATP
Features of Mitochondrial inheritance (is female only) (5)
optic atrophy neuropathy diabetes epilepsy sensory neural hearing loss
femoral nerve sensory supplies the
anterior-medial thigh
Median nerve palsy
weakness of thumb abduction (abductor policis brevis)
Ulnar nerve palsy
Inability to abduct or adduct fingers
Radial nerve palsy
Wrist drop
Gilbert’s syndrome Features (2)
painless jaundice (normal LFTs other than BR) non-specific illness
Hypoglossal (CN XII) palsy
tongue deviates TOWARDS the side of defect - due to paralysis of tongue muscles
Antiphospholipid syndrome antibodies (3)
B2 glycoprotein, lupus anticoagulant, anti-cardiolipin
Causes of Respiratory Alkalosis - causes of hyperventilation
Pregnancy Anxiety Hepatic failure salicylates, progresterone interstitial lung disease
Peutz-Jeghers syndrome Features (3)
hyperpigmentation nose and mouth
GI bleeding
Risk of colon, pancreatic ca
Marfans gene abnormality
Fibrillin-1
Analysis of variance (ANOVA) statistical analysis description
comparison of two of more means
Primary biliary cholangitis antibody
Anti mitochondrial M2
Iron overdose antidote
Desferrioxamine
Pancreatic Ca gene mutation
KRAS
Hereditary spherocytosis gene mutation
Spectrum and ankyrin
Autoimmune encephalitis antibody
Anti LGI 1 (previously VGKC)
acute intermittent porphyria Mx
IV haem arginate
RET oncogene related to which type of thyroid cancer
medullary
Alkaptonuria/ Ochronosis features (2) - homogensitic acid oxidase deficiency
Chondrocalcinosis + arthritis
brown/ dark urine
Respiratory alkalosis drug overdose causes (2)
salicylates (aspirin)
theophylline
(hyperventilation)
Sjogrens disease antibodies
Anti RO
Anti La
Mixed Connective tissue disaese
features
autoantibody
F - raynauds, ILD, pericarditis
Antibody - Anti-Ribonucleoprotein
