B6.3 (3) Flashcards
- monoclonal antibody uses - vaccines + medicines in the treatment of disease - aspetic techniques - new medicines discovery + development
what is the role of monoclonal antibodies in pregnancy testing?
- pregnant women produce hCG hormones (from 2 weeks) after conception (in urine)
- role is to bind to antigens on the hCG hormone + cause a colour-change reaction
- home pregnancy test consists of a short stick, impregnated with a band of these monoclonal antibodies. When urine containing hCG contacts the antibodies, a line appears on the stick, indicating that the woman is pregnant
what is the role of monoclonal antibodies in detecting diseases (such as prostate cancer)?
- they can be developed to bind to specific cancerous antigens (such as ones for prostate cancer)
- and so can bind to them and act as a marker (can confirm presence)
- may have a fluorescent dye
- once tumour identified = treated + removed (often at early stage)
what is the role of monoclonal antibodies in the treatment of diseases (like targetting cancer cells)?
- they can be developed to target specific cells
(kill them/prevent from operating efficiently) - can carry radioactive substances/drugs directly to cancer cells (increasing the effectiveness of the treatment. This also minimises damage to surrounding tissue)
what is the benefit of using monoclonal antibodies to treat cancers?
minimise damage to surrounding tissue and other cells (only cancer cells)
advantages of monoclonal antibodies? 3
- bind to specific cells only (healthy cells not affected)
- engineered to treat many diff conditions
- can easily produce a lot of them
disadvantages of monoclonal antibodies? 3
- difficult to attach them to drugs
- expensive to develop
- were produced from mice lymphocytes = often triggered immune response in humans
define a vaccine
- a solution which
- contains a small amount of weakened or dead versions of a pathogen which
- stimulates white blood cells to
- produce antibodies complimentary to the antigens
what does a vaccine force the immune system to do?
produce antibodies specific to that pathogen (by the lymphocytes)
what is immunity?
when lymphocyte cells produce enough antibodies fast enough to destroy pathogen before it causes disease
BUT PATHOGEN STILL ENTERS BODY
how do vaccines help in the long term?
upon the real infection, the body has some antibodies in the form of memory cells
(fight off disease faster and without becoming ill)
positives and negatives of vaccinations?
POS
- eradicated many disease
- epidemics prevented through herd immunity
- childhood immunisations led to fewer children dying of infectious diseases
NEG
- not always effective with providing immunity
- can have severe allergic reactions
what are antibiotics?
medicines that kill bacterial pathogens inside the body
substances that slow down or stop the growth of bacteria .
would one antibiotic kill all bacteria?
no, different antibiotics are effective against different types of bacteria
how do scientists identify the bacteria making you ill?
- doctors send blood sample to lab
- scientists grow bacteria in agar plates
- and treat it with different antibiotics
how do antibiotics affect bacteria?
- inhibit cell processes
- stop them from growing
(ie. stop building cell walls)
- which stops diffusion/protein synthesis
what is the problem with antibiotics?
overuse may lead to antibiotic-resistant bacteria (non-resistant bacteria are killed off)
explain the use of antiseptics in the prevention/treatment of disease
- kill or neutralise all types of pathogens
- do not damage human tissue (so good in surgeries)
can one antiseptic kill all microorganisms?
no, different antiseptics act on different microorganisms
difference between a disinfectant and antiseptic?
- disinfectant only applied to non-living surfaces (are harmful to human tissue)
- antiseptic do not damage human tissue
what are antivirals?
drugs that inhibit the function of viruses (usually by preventing them from replicating)
can antivirals kill viruses?
and explain why
no, not directly
- as viruses go into cells, and so antiviral drugs would have to kill body cells as well
how can antivirals treat viral diseases? (3 marker)
- blocking virus from entering a host cell
- preventing virus from releasing genetic material
- preventing virus from inserting genetic data into host cell’s DNA
are most antiviral drugs specific?
yes, they are designed to act on one type of cell
what is the problem with antiviral drugs?
- hard to produce an effective antiviral
- as viruses mutate very fast
- and so would not be effective
what are antiseptics commonly used to do?
sterilise a wound to avoid infection + spread of disease
define a zone of inhibition
the area on an agar plate where bacteria cannot grow (as antibiotics kill it)
what does the zone of inhibition show?
the effectiveness of an antibiotic
how do you measure the zone of inhibition?
calculate the area of it (using πR²)
- ie. measure diameter (then divide by 2)
passive vs active immunity?
passive = not have to make own antibodies (ie. from mother’s milk)
active = have to produce own antibody (ie. vaccinations)
explain what an aseptic technique is
a technique used to ensure that no foreign micro-organisms are introduced into a sample being tested
what is the use of alcohol in culturing organisms?
acts as a disinfectant to sterilize equipment + the working area
what is the use of flaming when culturing organisms?
- flame the neck of test tubes
- causes air to expand + push bacteria away
- kills bacteria on neck of tube
- ensures no microorganisms enter the mouth of the vessel + contaminate medium
what is autoclaving?
a pressurised chamber where apparatus is exposed to high pressure stem, high temp for 15ish minutes
how is autoclaving used in culturing organisms? 3
- kills all microoganisms present
- sterilise apparatus
- prevents unwanted contamination
give 3 measures to stop contaminants falling onto/into the growth media
- work carried close to bunsen burner flame (creates updraught of warm air to carry away airborne microorganisms)
- lids kept on bottles + dishes at all time
- wearing gloves (prevent skin to sample)
what must you remember about sealing a petri dish?
do not tape around circumference (microbes need oxygen)
- do not want to encourage growth of anaerobic bacteria (more harmful)
why are petri dishes incubated in schools at no higher than 25C?
do not want to grow at body temp (easily infect)
what does the term innoculate mean?
intentionally introduce a microorganism to an organism
what is the growth medium used to grow bacteria?
agar jelly
how should petri dishes be stored and labelled?
- stored upside down (so condensation does not contaminate bacteria
- labelled on base (if lid falls off, the bacteria is still labelled)
what is the main thing to remember when transferred bacteria to an agar plate?
- the inoculation wire must be flamed before (heating in blue flame)
- or dip it in pure alcohol
in what shape are bacteria inoculated onto a petri dish? (and why so)
- in streaks
- to separate them into different colonies
where do new medicines usually come from?
- plant extracts (ie. aspirin)
- microorganisms
- usually from present substances (easier than creating one from scratch)
give an example of a medicine from microorganisms
the antibiotic penicillin (from fungi)
what are the two main stages of the development of new diseases?
preclinical
clinical testing
what happens during preclinical testing?
and what is each stage used for
- drug tested using computer simulations
- tested on human cells grown in lab
(see toxicity and if it would help) - tested on bacteria, and on tissue cultures
- drug tested on animals (often mammals)
show effectiveness, toxicity, side effects
what happens during clinical testing?
- small dose tested on healthy humans (check safety, slowly increase dose)
- tested on volunteers with condition (find optimum dosage + lowest toxicity)
- drug tested on large number of people
(monitor side effects + safety)
positives and negatives of using computer simulations?
pos - cheaply test many drugs
neg - does not show effect on entire body
use of a double-blind test?
- avoid unconscious bias
ie. doctors more alert to patient’s symptoms if they know have real drug
what is a double blind test?
neither doctors nor volunteers know if theyve been given the real drug/placebo
give two examples of a bias which is prevented by a double-blind test?
- some people may feel better as they know have real drug
- some people may report more side effects (if they know have real drug) - hyperaware
what is a placebo?
an exact replica of the drug being tested, but has no active ingredients (ie. may have a sugar solution)
Mechanical valves evaluation
- longer lasting
- blood clots more likely
- patient has to take anti clotting medicine for rest of their lives
- medication can lead to excessive bleeding
- some patients say they can hear the valves openings and closing
Biological valves evaluation
- no additional medication required
- ethical issues surrounding use of animal tissue
- valve may harden
- more likely to need further operation or another new valve • more likely to be rejected
- more likely to need (immuno-suppressant) medication
Explain why a placebo group is used in drug testing (3)
- control
- verifies the problem is treated
- checks that drug is working, and not a psychological effect
Summary of the process of developing a new medical drug (6 steps)
- drug is tested using computer models and human cells grown in the laboratory. Many drugs fault at this stage because they damage cells or appear not to work.
- Drug is tested on animals (nematode worms/fruit flies/mice) to study any side effects
- Drug is tested on a small group on healthy human volunteers to check its safety. Testing drugs on humans is known as clinical trials.
- Drug tested on a small number of volunteer patients who have the illness, to ensure it works.
- Drug tested on large numbers of volunteer patients to monitor drug effectiveness, safety, dosage and side effects.
- Drug approved and can be prescribed
