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B6 Preventing and Treating Disease (Vaccination (Immunisation (a dead or…
B6 Preventing and Treating Disease
Vaccination
for serious diseases, the immune system has no time to produce the right antibodies
vaccination (or immunisation) can protect you from serious diseases
Immunisation
a dead or inactive (safe) forms of pathogen make a
vaccine
introduced into the body (often injected)
stimulates immune response to make specific antibodies and destroys antigens
specific antibody is remembered which makes you immune
if the same live pathogen invades, correct antibody can be produced rapidly
no disease symptoms occur
vaccines protect against bacterial and viral diseases
MMR vaccine protects against measles, mumps and rubella
Herd Immunity
if most of the population are vaccinated, the spread of the pathogen is much reduced and may disappear
smallpox has been completely wiped out by vaccination
protects the entire society and those not vaccinated
pathogen will not spread to them
if not enough people are vaccinated, herd immunity is lost
risk of outbreaks
epidemics within a country
pandemics across many countries
people may fear the safety of the vaccine
disease can reappear
takes money and effect to reach global herd immunity
WHO (world health organisation) wants 95% of children to have 2 doses of measles vaccine
Antibiotics and Painkillers
Painkillers
relieve and treat the disease symptoms
usually for viral diseases
waits for immune response
do not kill the pathogen
do not cure you any faster
Aspirin
thins blood/ pain relief
anti-inflammatory
Paracetamol
interferes with receptors to brain
Ibuprofen
anti-inflammatory (reduces swelling and pressure)
Antibiotics
antibiotics kill pathogenic bacteria inside the body
antiseptics and disinfectants are too poisonous to use inside the body
antibiotics don't damage body cells
cures bacterial diseases
cannot treat viral diseases
virus reproduce
inside
body cells
treatment for viral infections also damages body cells
taken as a pill or syrup
can be put straight into bloodstream for faster effect
specific bacteria treated with specific antibiotic effective against them
some antibiotics kill a
wide range
of bacteria
some antibiotics are
specific
to a particular bacteria
strains of antibiotic-resistant bacteria have evolved
some bacteria are resistant to
all
known antibiotics
the antibiotic no longer kills the bacteria
more people could die from incurable bacterial diseases
scientist need to find new drugs to kill antibiotic-resistant bacteria
antibiotics shouldn't be overused and overprescribed
should only be used for diseases you can't naturally overcome
the
full course
of the medicine should be taken
prevents more multi-resistant bacteria evolving
Drug Discovery & Development
Discovery
modern new drugs are synthesised in the lab using computer models
starts from chemicals extracted from plants, animals or microorganisms
promising compounds can be modified to be more effective
Plants
digitalis and digoxin are extracted from the foxglove plant
drugs used to strengthen heart alongside modern drugs
aspirin painkiller extracted from willow tree bark
Felix Hoffman synthesised aspirin
drug works better
has fewer side effects
Microorganisms
Discovering Penicillin
in 1928, Alex Flemming was growing bacteria and he left the lid off his culture dishes
he notices some of the culture plates had mould growing on them
the mould spots had rings of clear jelly around it
a substance had killed the bacteria
he called it 'penicillin' after the
Penicillium
mould that produced it
Alex Fleming tried to extract the active juice from the mould but failed
10 years after discovery, Ernest Chain and Howard Florey successfully extracted penicillin
they tested penicillin on a infected patient and cured him
showed penicillin could cure bacterial diseases in humans
working with Pfizer company, penicillin was produced on an industrial scale
used in WW2 to save lives and is still used today
first discovered antibiotic
Future Medicines
Noni Fruit
used in traditional medicine in Costa Rica
treats infections and non-communicable diseases
used for food and drink with no health issues
research shows it has antibiotic properties
Soil Microorganisms
global soil samples taken to find antibiotic microorganisms
only 1% soil microorganisms can be cultured in lab
special technology needed
in 2015, a new antibiotic discovered from some soil bacteria
has destroyed all antibiotic resistant bacteria so far (Inc. MRSA)
Development
new medical drugs are tested extensively for efficacy(effectiveness), toxicity and dosage
drugs should be
effective
at curing the disease or relieving symptoms
safe
(non-toxic) for patients and with no unacceptable side effects
stable
drugs to be taken in normal conditions and stored for some time
can be taken in to reach its target, and removed easily out of the body
developing a new drug can take 12 years and cost $1700B including £failures
Preclinical Testing
many possible drugs are tested on cells, tissues and organs in the lab
tests for
toxicity
and
efficacy
5000 -10000 compounds
many chemicals fail at this stage
takes 4.5 years
10-20 drugs are then tested on
small animals
and then
larger animals
see how they work in
living organisms
information on possible
side effects
takes 1.5 years
preclinical testing is used as models to predict drug behaviour in humans
Clinical Trials
low dosages
are given to
healthy
human volunteers
checks for
safety
and
side effects
tests 5-10 compounds
takes 1.5 years
if drug is safe, it is trialled on
a small no. of
patients
to find out its
efficacy
(if it treats the disease)
tests 2-5 compounds
takes 2.5 years
if safe and effective, bigger trials with
higher dosages
on patients take place
to find the optimum drug
dosage
tests 1-2 compounds
takes 1.5 years
Licensing
if a drug pasts all the legal tests, it is
licensed
drug safety is still monitored throughout its use
doctors can prescribe the drug
takes 1.5 years
drug testing results are published like scientific research
results scrutinised by
peer review
other scientist can check results for
fake claims
national bodies (National Institute for health and Care Excellence NICE) look at published results
decide on good value drugs to invest into NHS
Double Blind Trials
in patient trials, double blind trials are used to verify the genuine
efficacy
some patients are given the drug and some a
placebo
a
placebo
doesn't contain the new tested drug
placebo may contain an existing drug which treats the disease
so patient is not deprived of treatment
patients are randomly allocated to different groups
neither
doctor
nor
patient
knows who is given drug or placebo
rules out any biased judgement
patients health is monitored carfully
Monoclonal Antibodies
monoclonal antibodies are a form of medical treatment using the immune system
proteins made to target particular cells or chemicals in the body
antibodies are specific to one binding site of a specific antigen
cell surface protein molecules or free protein molecules act as
antigens
antibody may only be found on specific body cell or specific chemical
antibodies produced from a single clone of cells
Production
mouse lymphocytes are stimulated to make a particular antibody
mouse lymphocyte combined with a tumour cell to make a hybridoma
single hybridoma cells divide to make clones of the cell
large no. of identical cells that all produce the same antibodies
monoclonal antibodies are collected and purified to be used
recently, mice cells are also combined with human cells
produces monoclonal antibodies less likely to be rejected by humans
hybridoma cells
combines antibody-specific lymphocytes and tumour cells
B lymphocytes naturally produce antibodies but cannot divide
so can't be used to produce antibodies for medicines
tumour cells divide rapidly but don't make antibodies
makes a clone of cells
Uses
Pregnancy Tests
antibodies bind to the HCG hormone (human chorionic gonadotrophin)
hormone is produced in early pregnancy
small amount of the hormone are passed out in the urine
produces a colour change indicating HCG presence
Disease Diagnosis
antibodies bind to specific antibodies on a pathogen,
blood clot
or
cancer cell
monoclonal antibodies may carry markers for easy build up detection
allows for early disease detection
used in blood test for prostate cancer
monoclonal antibodies used to detect plant, animal and human diseases
Measuring and Monitoring
monitors the levels of hormones and other chemicals in the blood for diagnosis
used in screening donated blood for HIV infection
detecting illegal drugs taken by athletes
detecting syphilis infections
Research
scientists can locate specific molecules in a cell or tissue
markers of fluorescent dye are added to antibody
build of fluorescence observed where desired molecule is
Disease Treatment
monoclonal antibodies may be the 'magic bullet' drug targeted at specific pathogens and disease
other healthy body cells not harmed
some are developed to target specific antigens on certain
cancer
cells
some
trigger the immune system
to recognise, attack and destroy cancer cells directly
monoclonal antibody bind to specific antigen on cancer cell
signals to the immune system by making the cancer cell more noticeable
some
block receptors
on cancer cells, removing stimulus to grow and divide
monoclonal antibody binds to the receptor site
growth-stimulating molecule can no longer bind to cancer cell
some carry
toxic drugs, radioactive substances or growth inhibiting chemicals
directly to cancer cell
attached chemicals or radioactivity kills the cancer cell
monoclonal antibody binds to antigen on cancer cell
Advantages
only binds to specific diseased cells that need treatment
healthy cells are not affected
conventional cancer treatment carries drugs around the body, damaging other body cells
radiotherapy cancer treatment is area targeted but still affects healthy cells nearby
very specific so could treat a wide range of condtions
Disadvantages
not as widely used yet as originally hoped
expensive to develop and produce
but has potential to be cheaper to develop than conventional drugs
side effects due to human immune response to mouse antibodies
using mouse-human hybridomas could reduce side effects
only using fractions of antibodies to carry drugs
doctors are now prepared and ready to treat the side effect symptoms
producing the right monoclonal antibody and attaching them to drugs and chemicals is very difficult