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Beta Blockers Against High Blood Pressure

• Prolonged, high blood pressure → hypertension, risk factor of CHD (coronary heart disease)!
• Risk factors associated with hypertension are stress, obesity, smoking, high intake of NaCl and alcohol
• Smooth muscle in artery wall thickens → narrows lumen of the artery → heart must beat faster → contracts with greater force than normal
  • Increased risk of thrombosis and atheroma (fatty deposits form in artery walls)
  • β-receptors found on plasma membrane of smooth muscle cells in arteries, arterioles and heart
  • β-agonists are chemical messengers that fit into and stimulate β-receptors / muscle cells in the walls of arteries relax (increases size of lumen)
  • β-blockers are antagonists of β-agonists / block β-receptors on surface of muscle cells in arteries and heart due to their similar shape / β-agonist cannot bind anymore / reduces hypertension
• [EXAM] β-blocker binds to receptor / receptor on heart (muscle cells) / adrenaline cannot bind / blood pressure falls because heart rate reduced/force of contraction reduced

Antibiotics

• Produced as natural secretions by bacterial or fungal cells
  • Bacteria and fungi are secondary metabolites (produce antibiotics during a late stage of their life cycle)
  • Antibiotics inhibit growth of natural competitors
  • Gives antibiotic-secreting population an advantage in colonising it
• Antibiotics harm pathogenic bacteria by
  • Bacteriostatic antibiotics that are slowing down their growth rate
  • Bactericidal antibiotics that kill pathogenic bacteria (in correct concentration)
• Narrow-spectrum antibiotics (e.g. penicillin) are only effective on a few pathogens
• Wide-spectrum antibiotics (e.g. chloramphenicol) are effective on many pathogens
• Prevent formation of bacterial cell walls
  • Bacteria occupy a solution with a more negative water potential than their own cytoplasm
  • Without the cell wall, bacteria are exposed to this hostile environment
  • As a result, bacteria will swell, burst and die
  • > Review the principles of water potential
• Prevent formation of bacterial proteins
  • By inhibiting DNA transcription or mRNA translation
  • Bacteria are unable to synthesise proteins → affects the metabolism of bacteria
• NOTE: Antibiotics do not affect viruses

Monoclonal antibodies

Hybridoma

• B-lymphocytes are fused with tumour cells in laboratory cultures
• They divide rapidly to form a clone of identical cells
• Specific monoclonal antibodies are continuously produced and useful as
  • Some are tumour markers (antigens not present on non-cancerous cells)
  • Monoclonal antibodies will only attach to cancer cells
  • Anti-cancer drug attached to monoclonal antibodies will deliver the drug directly to the cancer cells

Uses of monoclonal antibodies

• Monoclonal antibody is an antibody that is of just one type
• Used to target the treatment of cancer cells or to screen (AIDS) in contaminated blood
• Antibody direct enzyme prodrug therapy techniques (ADEPT)
  • Monoclonal antibodies are tagged with an enzyme that converts the prodrug (inactive drug) to an active form that kills cells (i.e. is cytotoxic)
  • The prodrug is injected in high conc
  • Attached to a monoclonal antibody, enzyme activates the drug and kills only cancer cells
• In immunoassays, they can be labelled (radioactively) making them easy to detect
• In the enzyme-linked immunosorbant assay (ELISA) technique, they are immobilised on an inert base and a test solution is passed over them
  • Target antigen combines with immobilised monoclonal antibodies
  • Second antibody attaches with an enzyme and binds to the monoclonal antibodies and to the target antigen as well
  • Substrate is added which is converted to a coloured product by the added enzyme
  • Conc. of colour tells us the amount of antigens present in the test solution
• Used to detect drugs in urine of athletics or in home pregnancy tests (where an antigen in human chorionic gonadotrophin (hCG) is secreted by the placenta)
• Transplanted organs have non-self-antigens triggering antibodies to attack the organ, leading to its rejecting
  • T-Lymphocytes are needed for B-lymphocytes to function
  • Monoclonal antibodies against T-lymphocytes can be used to prevent B-lymphocytes from functioning, thus blocking the rejection of transplanted organs
• [EXAM] Helping to diagnose between two pathogens because
  • Antigens are on cell-surface membrane
  • Monoclonal antibody reacts with specific antigen only
  • Thus, detects presence of special bacteria because of a different antigen on another, different bacteria