Preventing and treating disease

• • Every cell has proteins on its surface called antigens 
• A person has ‘self-antigens’ unique to them on every cell in their body
• Pathogens have ‘non-self’ or foreign antigens on their surface
• • Phagocytes engulf the pathogen 
• Lymphocytes produce antibodies and antitoxins
• • If we are exposed to the same pathogen again they react quickly destroying it before we become ill therefore becoming immune
• in a vaccine there are small amounts of dead or inactivated form of a pathogen
• a vaccine an immune response like an infection
• memory cells are produced after a vaccine so that when a live pathogen is encountered the body will have a quick response and immunity
• Herd immunity - When enough people are vaccinated, the chance of the disease spreading to an unvaccinated person is much lower. 
• Antibiotics are substances that slow down or stop the growth of bacteria
• antibiotics on work on bacteria
• antibiotics can be taken orally or intravenously
• • Some are very specific - narrow spectrum and only work on one or a few types of bacteria 

  Some have a broad spectrum, and work on a range of bacteria
• • They damage bacterial cells without damaging the body cells
• the first antibiotic was penicillin
• antibiotics cannot kill viral pathogens
• • Some bacteria are already resistant to all known antibiotics
• Bread mould is a fungus, these produce antibiotic chemicals, and was used for wounds in ancient Egypt
• in 400BC people were told to chew on willow bark to relieve pain because the bark contains salicylic acid, developed to asprin
• Digitalis and digoxin have been used since the 18th century to strengthen the heart rate/beak, both extracted from foxglove plants
• Clinical trials allow scientists to find out if they are toxic and have any side effects 
• • Efficacy – prevents or cures a disease or makes you feel better.
• • Toxicity – not too toxic, not too many side effects.
• • Stability – can be used and stored for a long time.
• • Successfully enters and leaves the body – reaches target and then cleared from your body
• things that make a god medicine are,efficiency, toxicity, stability, successful entry and exit
• how to make sure test are valid, double blind trials, placebos
• • Double blind trials – patients with the target disease take part in the trial
• • Placebos – are given to some of the volunteers (does not contain the drug)
• National Institute for Clinical Excellence (NICE)
• steps for development of drugs, drug discovery (4.5 years), preclinical testing (1.5 years), tested on human volunteers (1.5 years), tested on patients (first round 2.5 years , second round 1.5 years), licensed and prescribed (1.5 years)
• first known drug trials took place by William Withering, an English Botanist and Doctor
• meaning of monoclonal antibodies

  
• All the cloned lymphocytes produce the same antibodies and all target the same antigens 
• Monoclonal antibodies are made by cloning just one lymphocyte 
• We take mouse lymphocytes and fuse them with cancer cells → hybridoma cells
• Hybridoma cells divide easily, produce antibodies, easy to clone (lots of identical cells), all produce the same antibodies (monoclonal antibodies) then can then be collected and purified 
• ways to use Mabs -

  1. Direct use – triggers the immune system to recognise and attack and destroy cancer cells
  2. Blocking receptors on the surface of cancer cells to stop them growing and dividing
  3. Carry toxic drugs or radioactive substances for and radiation therapy, or chemicals that stop cells growing and dividing to attack the cancer cells directly, without harming body cells