People and Illness Week 3 Flashcards
What affect does alcohol consumption have on life expectancy?
Even below recommended limits (<12.5 units/per), alcohol consumption significantly decreases life expectancy
In the UK, how many grams of alcohol constitute a standard ‘unit’ of alcohol?
8g, percentage per litre is the number of units
Describe the trend of estimated deaths due to liver disease compared with the general population
Increasing
How does the risk of injury due to alcohol consumption vary depending on whether it is consumed alone or with meals?
Lower risk of injury if alcohol is consumed with meals
What factors affect the consumption of alcohol by a population?
Economic stability - disposable income
Availability of alcohol - licensing/legality
What is the peak admission age of patients with alcoholic liver disease?
Early/mid 50s
List the risk factors for alcoholic liver disease
The amount, the type and the frequency of alcohol consumption - daily drinking > binge
Alcohol abuse at a young age
Female
Overweight for at least 10 years
Explain the term ‘sick abstainers’
Those who abstain from alcohol who have previously abused alcohol, abstain due to health problems/fear of health problems in the future - makes some data appear as though those who abstain are at higher risk of developing disease, damage is already done in this group
What changes occur in the liver due to chronic excessive alcohol exposure?
Alcohol exposure leads to steatosis in 90-100% of heavy alcohol abusers, which can be reversed by abstinence.
Severe exposure will leads to hepatitis, which can develop from steatosis, hepatitis occurs in 10-35% of heavy alcohol abusers.
Abstinence can reverse hepatitis to steatosis.
Repeated attacks/continued exposure to alcohol can cause cirrhosis to develop from steatosis or hepatitis, which occurs in 8-20% of heavy alcohol abusers.
Describe the structural changes seen in the liver in steatosis
Fatty change
Perivenular fibrosis
Mactosteatosis in zone 2 and 3 - macrovesicular globules of fat
Enlarged liver, yellow colour due to fat accummulation
Describe the structural changes seen in the liver in hepatitis
Liver cell necrosis Inflammation - neutrophils infiltrate Mallory bodies - hyaline Fatty change Swollen hepatocytes Giant mitochondria Steatosis Collagen in zone 3
Describe the structural changes seen in the liver in cirrhosis
Fibrosis
Hyperplastic nodules - micronodular
Irregular nodular appearance
What is the final step in alcohol metabolism?
All processes produce acetaldehyde, which is oxidised to acetate by acetaldehyde dehydrogenase (in the mitochondria)
Describe the pathways involved in alcohol metabolism
Mostly oxidative metabolism in the cytosol by alcohol dehydrogenase
+ Microsomal ethanol oxidising system which uses cytochrome P4502E1 and produces reactive oxygen species
+ Catalase in perioxisomes which produces reactive oxygen species
How is alcohol metabolised in small/moderate amounts?
Oxidative metabolism in the cytosol by alcohol dehydrogenase to acetaldehyde then oxidation to acetate by acetaldehyde dehydrogenase in the mitochondria - other pathways only recruited in alcohol excess
What is the effect of chronic alcohol excess on alcohol metabolism?
Saturates normal pathway, induces recruitment of catalase and cytochrome P4502E1 (MEOS)
Increased production of acetaldehyde, acetate and reactive oxygen species
What are the consequences of alcohol metabolism on the body?
Acetaldehyde production - binds to proteins and DNA (immunogenic), stimulate collagen production by stellate cells
Acetate production - increased acetyl coA promotes inflammation by histone acetylation
Increased NADH/NAD ratio - increased fatty acid synthesis, reduced fatty acid oxidation (promotes steatosis)
Non-oxidative metabolism - fatty acid ethyl ester production (promotes steatosis)
Describe the conversion of NAD to NADH in alcohol metabolism
Cytosol oxidative metabolism -
NAD –> NADH
MEOS -
NADPH –> NADP
Mitochondrial conversion of acetaldehyde to acetate -
NAD –> NADH
What is the net change in NAD/NADH due to alcohol metabolism? What effect does this have?
Increasing NADH:NAD
Increasing NADH drives the electron transport chain - leaks electrons e.g. superoxide ions, hydrogen peroxide ions which are reactive
What produces reactive oxygen species in alcohol metabolism?
Largely through MEOS (especially CYP2E1) but catalase activity may contribute (especially in fasted state)
What are the effects of reactive oxygen species?
Activate redox-sensitive transcription factors such as NF-kapaB which leads to increased TNF-alpha production
Promotes lipid peroxidation which promotes inflammation and damages mitochondral membranes leading to apoptosis
What is the effect of TNF production?
Promotes apoptosis and necrosis, and activates stellate cells to produce collagen leading to fibrosis
What effect does alcohol have on the intestines?
Increases permeability, allows endotoxins to enter the portal circulation - portal circulation endotoxaemia.
This promotes activation of Kupffer cells which in turn promote liver injury - more proinflammatory cytokines (TNF-alpha) and reactive oxygen species.
Describe the changes which occur in hepatocytes following alcohol-related liver injury
Production of reactive oxygen species, activation of NF-kapaB, IL-8 and TNF recruition, neutrophil activation
How is the immune system changed in chronic alcohol excess?
Alcohol consumption stimulates the immune system to react to and damage the the liver
Describe the intrinsic apoptosis pathway
Intrinsic apoptosis (mitochondrial) pathway induced by oxidative stress - free-radicals, reactive oxygen species, toxins, radiation
Leads to leakage of pro-apoptotic factors from mitochondria (i.e. cytochrome-c), regulated by Bcl-2 proteins
Pro-apoptotic factors from mitochondria activate caspases leading to cell degradation
Describe the extrinsic apoptosis pathway
Initiated by TNF-alpha
Binding to TNF receptors leads to caspase activation via (Fas-associated death domain) and TRADD (TNF receptor-associated death domain) proteins
How does the process of apoptosis occur?
Proteolytic caspases degrade cellular organelles
Cell components broken down into vesicles (apoptotic bodies)
Compare apoptosis and necrosis
Apoptosis: Natural cell death Stimulated by cell signals Beneficial Produces cell fragments that are able to send signals that facilitate phagocytosis
Necrosis Traumatic cell death Stimulated by factors external to cells Fatal Cannot send signals, leads to build up of dead tissue and cell debris
How does apoptosis contribute to liver injury in excessive alcohol consumption?
Apoptosis is usually a benign process, overstimulated in alcoholic liver injury = progressive damage without benefit
What factors may exacerbate the effect of excessive alcohol consumption on the liver?
Malnutrition - vitamin and trace element deficiencies
Obesity
Why are many alcoholics malnourished?
Drinking to excess, usually don’t eat adequately, can get 60-70% of calories from alcohol
How does malnutrition exacerbate liver injury?
Depletion of trace elements (i.e. zinc) may exacerbate ROS production and promote apoptosis
Vitamin deficiency may lead to impaired metabolism of methionine and reduction in gutathione
Mitochondria in chronic alcohol excess more susceptible to ROS, normally protected by mitochondrial survival factors (MnSOD, Bfl-1, Bcl-XL) and anti-oxidants (glutathione, alpha-tocopherol)
Depleted glutathione - alcohol induced cytotoxicity.
Which vitamin deficiencies increase susceptibility to cytotoxic damage in alcoholic liver disease?
Glutathione synthesis from methionine reduced by deficiency in folate, vitamin B6
How is glutathione synthesised?
Uses dietary sources of folic acid (e.g. leafy green vegetables), methionine to S-adenosyl-homocyteine to homocysteine to cryathionine to cysteine to gamma-glu-cysteine to glutathione
Which vitamins are needed for the production of glutathione?
Betaine (vitamin B)
Vitamin B6
Vitamin B12
What are the consequences of disrupted methionine metabolism?
Reduced S-adenosylmethionine:S-adenosylhomocysteine ratio:
Reduced transmethylation, impaired gene expression, increased caspase 3/8 expression
Apoptosis - increased TNF production (reduced IL-10)
Inflammation - reduced cystathionine beta-synthase activity
Reduced trans-sulfuration - reduced glutathione production (oxidative stress)
Describe the relationship between obesity and alcoholic liver disease
Alcohol induces a lipdystrophy - reduction in peripheral fat, increase in visceral fat
Induction of CYP2E1 by increased free fatty acids, insulin resistance and alcohol - increased ROS and further insulin resistance, metabolism of FFA to hydroxylated fatty acids
Obesity induced pro-inflammatory state - increased inflammatory mediators in response to endotoxaemia in obese patients
Obesity is a risk factor for alcoholic liver disease
Compare the features of non-alcoholic fatty liver disease and alcoholic liver disease
Similar histological features in both
Weight
NAFLD - elevated, ALD - variable
Fasting plasma glucose/HbA1c
NAFLD - often elevated, ALD - usually normal
AST/ALT ratio
NAFLD - <0.8 (more in advanced disease), ALD - >1.5
GGT
NAFLD - elevated or normal, ALD - markedly elevated
Explain the AST/ALT ratio in alcoholic liver disease compared with non-alcoholic fatty liver disease
AST in mitochondrial, ALT is cytoplasmic
Mitochondria remain intact in necrosis (predominant process in NAFLD)
Apoptosis breaks down mitochondrial membrane releasing AST (predominant process in ALD)
AST elevation also due to pyridoxine deficiency
AST not >500, ALT usually <300
Describe the pathological spectrum of alcoholic liver disease
Normal liver < steatosis < steatohepatitis < fibrosis < cirrhosis < hepatocellular carcinoma
Describe a non-invasive method of measuring the extent of liver disease
Fibroscan - transient elastography
Probe over rib cage measures the stiffness/firmness of the liver - soft/spongey = no fibrosis, hard/stiff = fibrosis
Which patient groups should be offered transient elastography?
To diagnose cirrhosis for men who drink over 50 units of alcohol per week and women who drink over 35 units of alcohol per week and have done so for several months
List the symptoms which develop as alcoholic liver disease progresses
Initially non-specific e.g. malaise, nausea
Progress to more clinical symptoms - hepatomegaly, fever, jaundice, sepsis, encephalopathy, ascites, renal failure
Why is fever a symptom of alcoholic liver disease?
Overstimulated immune system - many inflammatory mediators activated, active but dysfunctional so more susceptible to infection then sepsis
Describe the presentation of a patient with ‘clinically relevant’ alcoholic hepatitis
Newly jaundiced - bilirubin >80 umol/l (onset within 8 weeks)
Recent excess alcohol (within 8 weeks)
Exclusion of other liver diseases
AST < 500, AST:ALT ratio >1.5
Hepatomegaly, fever, leucocytosis, hepatic bruit - may feel well
What is the short-term mortality for a newly jaundiced patient with alcoholic liver disease?
Determined by the Glasgow alcoholic hepatitis score - takes age, white cell count, urea (renal function), prothrombin time ratio and bilirubin into account - score above 9 = 60% chance of death in the next 29 days if no medical therapy
How is acute hepatitis managed?
High dose prednisolone (corticosteroid) - reduces mortality, survival benefit greatest in patients with GAHS > 9
What volume of fluid can be held in the abdomen before ascites is clinically detectable?
5-6L - detected at lower volume with ultrasound
List the signs of chronic liver disease
Stigmata - spider naevi (from central arteriole, spread like the legs of spiders, only in distribution of venous drainage of vena cava), foetor encephalopathy
Synthetic dysfunction - tests of liver function e.g. prothrombin time, hypoalbuminuria
What is foetor?
Sweet smelling breath in advanced liver disease/portal hypertension
How can encephalopathy present clinically?
Spectrum - comatose/unarousable or ‘out of sorts’/not themselves
List the signs of portal hypertension
Caput medusae, hypersplenism (thrombocytopenia, pancytopenia)
What causes caput medusae?
After birth the vestigial ligament develops to separate the umbilicus from the systemic circulation.
Chronic increase in portal venous pressure means the a direct connection between the HPV and umbilicus envolves.
High blood pressure, blood is forced into superficial abdominal veins surrounding the umbilicus - gives prominent, wiggly vessels visible on surface.
How many spider naevi can be seen before clinical concern?
5
How can the severity of chronic liver disease be assessed?
Glasgow alcoholic hepatitis score
Childs-Tucotte-Pugh Score
Model for End-Stage Liver Disease - used to allocate donor organs in USA for liver transplant
What parameters are considered in the Childs-Turcotte-Pugh Score?
Encephalopathy, ascites, bilirubin, albumin, prothrombin time prolongation
Compare the clinical presentation of incidental and decompensated alcoholic cirrhosis
Incidental - no features of liver failure, ‘silent’, identified due to abnormal LFTs or abnormal imaging
Decompensation - presents with feature of advanced liver disease (variceal haemorrhage, hepatic encephalopathy, ascites/oedema, hepato-renal failure, hepatocellular carcinoma
What is the effect of cirrhosis on portal pressure?
Alcoholic cirrhosis leads to raised portal pressure, which causes porto-systemic shunting (anorectal, oesophageal, anterior abdominal wall)
How does portal hypertension lead to the complications of chronic liver disease?
Portal venous blood shunted back into the systemic circulation
Endotoxins in systemic circulation causes sepsis-like vasodilation (nitric oxide)
Dilation of blood vessels to gut means more blood to portal venous system and more portosystemic shunts
Shunts grow, eventually variceal haemorrhage - ammonia travels to brain causing encephalopathy
Vasodilation - BP down, reduced effective circulating volume, compensatory mechanisms (RAAS, catecholamines) cause sodium retention leading to ascites (use spironolactone to treat) and renal vasoconstriction leading to renal failure (hepatorenal syndrome)
Which drugs are commonly taken and by whom?
Mostly males
Cannabis in adolescents, cocaine in 20s, opiates in 30s
List common drugs and how they are taken
Heroin - oral, smoked, IV
Cannabis - oral, smoked
Cocaine - nasal, smoked, IV
Amphetamines (speed) - oral, nasal, smoked, IV
LSD (acid) - oral
Phencylidine/PCP (angel dust) - oral, nasal, smoked
Describe the factors which may influence adverse effects of recreational drugs
Directly due to drug -
Dose
Speed of entry
Individual sensitivity
Chronic/repeated use
Interaction with other compounds in the drug
Interaction with other drugs, including alcohol
Interaction with pre-existing pathologies
Indirectly due to drug -
Secondary effects of coma or fits
Infection risks
Accompanying lifestyle changes (homelessness, prostitution, trauma)
List the categories of common drugs
Alcohol Stimulants Sedatives Hallucinogens Organic solvents Performance enhancing drugs
Which neurochemical pathways does heroin act on?
Dopamine (reward), GABA/sedative activity
Which neurochemical pathways does cannabis act on?
Perception/association (serotonin/acetyl choline, THC/dopamine), GABA/sedative activity
Which neurochemical pathways does cocaine act on?
Dopamine (reward), noradrenaline (alertness)
Which neurochemical pathways do amphetamines act on?
Dopamine (reward), noradrenaline (alertness)
Which neurochemical pathways does alcohol act on?
Dopamine (reward)?, GABA/sedative activity
Which neurochemical pathways does LSD act on?
Perception/association (serotonin/acetyl choline/THC/dopamine)
Which neurochemical pathways does phencyclidine/PCP act on?
Dopamine (reward), GABA/sedative activity
Describe the sensations which alcohol gives and the transmitter/receptor which causes this
Euphoria/pleasure - dopamine, opiods
Anxiolysis/ataxia - increased GABA
Sedation/amnesia - increased GABA, decreased NMDA
How does increasing blood alcohol concentration change the effects of alcohol?
- 02-0.03% - mood elevation, muscle relaxation
- 05-0.06% - relaxation, increased reaction time/decreased fine muscle coordination
- 08-0.09% - euphoria, impaired balance, speech, vision, hearing, muscle coordination
- 14-0.15% - gross impairment of physical and mental control
- 20-0.30% - severely intoxicated, very little control of mind or body
- 40-0.50% - unconscious, death from respiratory depression
What are the physiological effects of alcohol?
Wernicke-Korsakoff syndrome Peripheral neuropathy Cerebellar degeneration Myopathy Cognitive decline Seizures Withdrawal effects Injury/intracranial haemorrhage
Describe the action and effects of stimulants
Enhance transmission at the catecholaminergic/dopinergic/serotonergic synapses
Increase behavioural and motor activity
Increase alertness/disruption of sleep
Euphoria
Confidence
Central and peripheral sympatheomimetic effects
Side effects - anxiety, insomnia and irritability
Describe the toxidrome of stimulants
Tachycardia Hypertension Risk of arrhythmia Sweaty Hallucination Agitation Dilated pupils Elevated temperature
What is serotonergic syndrome?
Triad of:
Altered mental status - agitation/confusion/seizures
Autonomic changes - hyperthermia, diaphoresis, diarrhoea, tachycardia, hypertension, salivation
Neuromuscular effects - myoclonus, clonus, hyperreflexia, tremor, rigidity
Hallucinations also common with serotonergic activation
Describe the pharmacokinetics of cocaine
Quick onset of action - seconds to minutes
Peak levels - minutes to 30 minutes
Rapid BBB penetration - high brain concentrations
Half-life in plasma - 30-90 minutes (longer pharmacodynamic action)
Describe the pharmacodynamics of cocaine
Blocks dopamine, noradrenaline and serotonin re-uptake
Inhibitory effect on postsynaptic dopamine receptors
Blocks the presynaptic transporter protein for dopamine - dopaminergic pleasure effect, noradrenergic excess (readiness)
Describe the pharmacokinetics of amphetamines
Quick onset of action - seconds to minutes
Peak levels - minutes to 30 minutes
BBB penetration
Half-life in plasma - up to 12 hours for ICE
Describe the pharmacodynamics of amphetamines
Enhance release of dopamine and noradrenaline from pre-synaptic terminals - dopaminergic pleasure effect, noradrenergic excess (readiness)
For how long are amphetamines detectable in the system?
Detectable for 48 hours in urine
What are the acute neurological problems associated with stimulants?
Motor - tremor, myoclonus, rhabdomyolysis, movement disorders
Seizures
Neuropsychiatric - restlessness, irritability, violence, psychosis
Autonomic - hyperpyrexia
What are the chronic neurological problems associated with stimulants?
Anxiety Sleep deprivation Paranoia Aggression Paranoid psychosis (more with amphetamines) Cognitive dysfunction
What physiological effect do stimulants have which can have serious circumstances?
Stimulants cause vasospasm, mediated by alpha-adrenergic stimulation (more alpha than beta signalling) - platelet aggregation is increased, evidence for accelerated atherosclerosis
How are stimulants associated with strokes?
Mostly haemorrhagic
Occurs soon after use - within 3 hours
More common if underlying pre-disposition
Infarcts more common with crack cocaine/methamphetamine - cocaine doubles the risk of ischaemic stoke
Outcomes same as patients with non-cocaine related stroke but patients are younger
List types of stimulants
Cocaine Amphetamines Ephedrine Pseudoephidrine Phenylpropanolamine Ephadra alkaloids Methylphenidate (Ritalin) MDMA
Describe the pharmacokinetics and pharmacodynamics of opiates
Sedation - u receptors
Dysphoria - kapa receptors/reduces GABA release (increases dopamine)
List common sedatives
Opiates - heroin
GHB
Describe the pharmacokinetics and pharmacodynamics of GHB
Dysphoria - stimulates dopamine release
Sedation - GABA receptor activation
Muscle twitching
Describe the opiate toxidrome
Pinpoint pupils Respiratory depression Bradycardia Hypotension Hypothermia Pulmonary oedema Seizures
Describe the sedative/hypnotic toxidrome
Ataxia Blurred vision Coma Confusion Delirium Sedation Pupils likely to be normal
Causes include anticonvulsants, benzodiazepines, GNB, ethanol
What are the acute neurological problems associated with sedatives?
Typically indirect:
Coma
Compressive nerve palsies
Anoxic brain injury
What are the complications of intravenous drug used?
Embolic infarction Infective endocarditis Abscesses Discitis Meningitis HIV related illness
Describe the pharmacodynamics of hallucinogens
Serotoninergic
Noradrenergic
Cholinergic
Describe the effects of hallucinogens
Psychedelics
Dissociative anaesthetics
Deliriants
Describe the cholinergic toxidrome
Defecation Urination Miosis (small pupils) Bronchoconstriction Bradycardia Emesis Lacrimation Salivation
Describe the mechanism of action and effects of MDMA
3,4 methylenedioxymethamphetamine
Taken orally
Structurally similar to serotonin - blocks serotonin and noradrenaline reuptake
Stimulant toxidrome and perceptual effects - thermoregulatory problems, hallucinations, CV complications
What are the neurological effects of hallucinogens?
Rare reports of stroke
Toxic psychosis
Dangerous behaviour
Wernicke’s type syndrome - Angel dust
Give examples of organic solvents
Toluene, hexane, benzene
What are the acute effects of organic solvents?
Lightheadedness/hallucinations