B6 Preventing and treating disease

    Cards (26)

    • All cells have unique proteins on their surface called antigens. Pathogens have different antigens from the ones in your body
    • White blood cells form memory cells to remember the antibodies made for a specific pathogen
    • Herd immunity: if a large amount of a population is immune to a disease it reduces the spread of the pathogen/disease
    • Vaccines require a dead or inactive pathogen being injected into you. This then stimulates your white blood cells to destroy the pathogen. The white blood cells produce memory cells so when the real pathogen enters your body the white blood cells can produce antibodies faster and destroy the pathogen quicker.
    • Painkillers such as aspirin and paracetamol don't get rid of pathogens in your body they only relieve symptoms of the disease
    • Antibiotics can only destroy bacteria inside of your body. Disinfectants are used for surfaces and antiseptics are used on the outside of your body
    • Antibiotics such as penicillin destroy bacterial cells without damaging any of your cells or tissue. Usually taken in the form of a pill or syrup or can be directly injected into the blood stream if a person is very ill
    • Drawbacks of antibiotics:
      • cannot destroy viral pathogens, it's difficult to develop a drug that can destroy viruses without damaging your own cells
      • strains of bacteria are evolving to be antibiotic resistant
    • Traditionally drugs were extracted from plants or microorganisms. Aspirin was found in the bark of willow trees. Most new drugs today are synthesised in the pharmaceutical industry.
    • Alexander Fleming discovered Penicillin. During his studies of growing bacteria he noticed there was a clear ring around the bacteria which meant something had killed it. He called the substance penicillin because it destroyed penicillium mould
    • Medicines have to go through extensive testing and trials to check if it wokrs well and is safe to use
    • A good medicine is:
      • effective - must prevent or cure a disease and make you feel better
      • safe - not toxic or have unreasonable side effects
      • stable - must be able to take the medicine under normal conditions
      • successfully taken into and removed from your body - must reach it's target and cleared from your system after it's done its work
    • Developing new drugs starts with preclinical trials:
      • drugs are first tested in the lab for toxicity and efficacy
      • they are then tested on cells, tissues and even whole organs
      • many drugs fail at this stage but if they pass they are then tested on animals (tested for dosage and side effects)
    • Clinical trials are after preclinical trials:
      • very low doses are given to healthy volunteers to test for side effects
      • a small number of patients take the drug to see if it treats the disease, then more people try the drug to find the optimum dose for treating the disease
      • If the drug passes all of these tests it is then licensed and doctors can prescribe it
    • In the human trials scientists use double blind trials to see how effective the new medicine is. A group of patients agree to take part in the trial. Some are given a placebo which won't do anything and others the medicine. Patients are chosen randomly who receives the medicine or placebo.
    • 'Double blind' means neither the doctor or patient knows who received the placebo or medicine so results are not biased
    • Hybridomas: combining cells from mice or people with cancer cells to form a new type of cell.
    • Lymphocytes produce antibodies and cannot divide. Tumour cells don't produce antibodies but can divide. Mice lymphocytes that were stimulated to produce a specific antibody are combined with a tumour cell making a hybridoma
    • The single hybridoma cell then divides to make a large number of cells that produce the same antibodies. The antibodies are then collected and purified which makes monoclonal antibodies.
    • Monoclonal antibodies can only bind to one specific antigen found only on certain cells in the body. Since monoclonal antibodies can only bind to one specific antigen they can be used in a number of ways
    • Pregnancy tests using monoclonal antibodies
      1. MA bind to the hormone HCG in the early stages of pregnancy
      2. Tiny amounts can be passed into the urine
      3. MA bind to the hormone in the pregnancy tests
      4. Colour change will appear meaning a positive result
    • Diagnosis of disease using monoclonal antibodies
      • MA can be used as a 'marker' to see where a disease is building up
      • Doctors can quickly detect problems
      • MA can bind to prostate-specific antigens (prostate cancer)
    • Measure and monitoring using monoclonal antibodies
      • Can be used to monitor levels of hormones or chemicals in the blood
      • Screening donate blood for HIV and detecting drugs or infections
    • Research using monoclonal antibodies
      • Can identify specific molecules in cells or tissue
      • MA bind to fluorescent molecules scientists can see and observe the build up of fluorescent dye
    • Advantages of monoclonal antibodies:
      • only bind to specific damaged cells that need treatment, healthy cells are not affected
      • could be used to treat a wide range of conditions
      • could develop cheaper treatments since it's already tested
    • Disadvantages of monoclonal antibodies:
      • Currently expensive
      • not as widely used/ successful when first developed but could have more side effects
      • technology was quite difficult to use, but it has now developed so it could be easier to use more MA?