Preventing and Treating Disease

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  • Created on: 18-03-19 09:48
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  • Preventing and Treating Disease
    • Vaccination
      • Lymphocytes and phagocytes
        • Lymphocytes produce antibodies which attach to the antigens in the pathogen to neutralise them
        • Phagocytes can readily destroy a neutralised pathogen by engulfing it
      • Herd immunity
        • If enough of the population is vaccinated it becomes very difficult for the pathogen to be transmitted and the population is essentially protected
          • Around 80 percent of the population needs to be vaccinated to eradicate the disease
      • Process of vaccination
        • Vaccines contain dead or inactive pathogens of a specific disease
          • The vaccine is usually injected into the body
            • Antigens in the vaccine stimulate the lymphocytes to produce the correct antibody
              • The antibodies destroy the antigen without getting the risk of disease
                • Memory cells remain in the body so when an infection occurs many white blood cells can be produced rapidly
                  • The body responds much more quickly to produce antibodies so you do not suffer from the disease as if you already had it
    • Effect of antiseptics or antibiotics on bacterial growth
      • Zone of inhibition
        • Antibiotics cause an area where there is no bacterial growth
          • The larger the zone, the more effective the antibiotic
      • Types of immunity
        • Active-natural
          • making antibodies after getting an infection
        • Active-artificial
          • dead or inactive pathogens cause antibody production in the body from a vaccination
        • Passive-natural
          • Antibodies from the mother are passed on to a foetus in the womb or through breast milk
        • Passive-artificial
          • Antobodies for a disease are put into the body
    • Antibiotics and medicines
      • Drugs are substances which alter the way in which the body works
        • It could affect the mind, body or both
      • Painkillers vs antibiotics
        • Painkillers are used to relieve symptoms by numbing nerve cells but do not kill pathogens causing the disease
          • example: aspirin
        • Antibiotics kill bacteria and can therefore cure the disease
          • example: penicillin
      • Antibiotic resistance
        • Bacteria can develop resistance to antibiotics as they have a natural mutation so they are not affected by it
          • Drug resistant bacteria multiply and thrive
        • MRSA
          • The bacterium MRSA has become resistant to a large number of antibiotics, including the currently most powerful drug methicillin
    • Drugs and trials
      • Alexander Fleming
        • Inventor of penicillin
          • Penicillin breaks down bacterial cell walls so they cannot replicate
      • Developing new drugs
        • Researchers target a new disease and make lots of new possible drugs
          • Preclinical trials - drugs are tested on cells in the lab to test their toxicity and efficacy
            • They are tested on whole animals in the lab to find out how they work in a whole system
              • Phase 1 clinical trials - drug is tested on healthy volunteers in low doses to check for side effects and then the correct dosage
                • Phase 2-3 clinical trials - tested on people suffering the disease in increasingly large numbers to test dosage. Phase 3 trials test new drugs against current ones, as there is no point developing a drug further if it is not better than those currently available
                  • The drug can then be granted a license and can be prescribed
                    • Phase 4 clinical trials - these continue after the drug has been approved and is being used to monitor long-term effects
      • Double blind trials
        • Patients with the target disease are given either a placebo or the new medicine with the active drug
          • Neither the doctor nor the patient knows who has received which until after the trials so as to prevent psychological bias
          • A placebo is a liquid or pill which resembles the drug being monitored but does not contain it
    • Monoclonal antibodies
      • Monoclonal antibodies are proteins which are produced to target particular cells or chemicals in the body
      • Process of antibody production
        • A mouse is injected with an antigen to start the formation of antibodies
          • The spleen cells that form antibodies are collected from the mouse
            • These are fused with tumour cells called mycloma cells
              • This forms hybridoma cells which are grown in the lab
                • Those that produce antibodies are separated and the monoclonal antibodies are collected
      • Uses of monoclonal antibodies
        • Pregnancy tests
          • Monoclonal antibodies bind to the hormone HCG produced by the embryo which is used to produce a colour change signalling a positive result as dyed monoclonal antibodies bind to it
        • Diagnosis of disease
          • Monoclonal antibodies are made to bind to specific antigens found on pathogens, blood clots and cancer cells
            • They may also carry markers that make it easy for doctors to see where they have built up, allowing them to detect problems before affecting the patient's health
        • Measuring and monitoring
          • Monoclonal antibodies are used in hospitals and labs to measure or monitor the levels of hormones and other chemicals in the blood
        • Research
          • Research scientists use monoclonal antibodies to locate and identify specific molecule in a cell or tissue
            • Monoclonal antibodies are linked to a molecule of fluorescent dye and when bound to the desired molecules, scientists can see what has happened by observing fluorescent build-up
      • Monoclonal antibodies treating cancer
        • Monoclonal antibodies can attach to antigens in the cancer cell and trigger the immune system by making the cells more noticeable with a signal
        • Monoclonal antibodies may bind to receptors on cancer cells so that growth stimulating molecules cannot attach to the cell and it can no longer grow and divide
        • Monoclonal antibodies can be used to carry drugs or toxic chemicals which attack the cell and kill it
      • Advantages and disadvantages of monoclonal antibodies
        • Advantages
          • bind to specific antigens
          • healthy cells are not affected unlike in conventional therapies
          • can be used to treat a range of diseases as they are specific
        • Disadvantages
          • expensive to develop
          • more side effects than expected which require treatment
          • mouse antibodies used can trigger an immune response in humans
          • producing the correct monoclonal antibody and attaching the drug can be difficult

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