hemostasis, antibody &antibiotic

• Hemorrhage


  Pooling and oozing blood during neurosurgical procedures
• Techniques and devices used by neurosurgeons to control bleeding

  • Bipolar electrocautery
  • Ligatures
  • Endovascular therapies
  • Bone wax
• Biological hemostasis devices


  Oxidized cellulose hemostats, absorbable gelatin sponges, or microfibrillar collagen hemostats
• Oxidized cellulose hemostats


  • Rapidly swell into a gelatinous mass when saturated with blood, aiding hemostasis
  • Fully absorbed within 7 to 14 days
  • Deliver superior draping properties and bactericidal protection
  • Do not stick or fall apart
  • Endoscopically compatible
• Microfibrillar collagen hemostats


  • Cause platelet aggregation, degranulation, and the release of coagulation factors that, along with plasma factors, enable the formation of fibrin
• Avitene


  The only collagen hemostat indicated for all surgical procedures, including neurosurgery and urology
• Forms of Avitene


  • Flour
  • Sheets (non-woven web)
  • Syringe (1 gram and 5mm)
• Avitene


  • Effective in controlling arterial bleeding in patients with platelet counts as low as 20,000 per cubic millimeter
• Forms of EndoAvitene


  • Preloaded in 5mm and 10mm endoscopic applicators
• Biological hemostats aid in platelet aggregation and help to stop bleeding in neurosurgical procedures, providing an excellent alternative to surgeons when conventional methods fail
• Monoclonal antibodies


  Antibody-based therapeutics developed in the mid 1970s by fusing immortal myeloma cells with antibody-producing B-lymphocytes
• Monoclonal antibody production process

  1. Initial immunization of a mouse with the antigen of interest

  2. Sacrifice mouse and remove spleen (enriched in B-lymphocytes)

  3. Screen for antibodies recognizing specific epitopes on the antigen
• Phage display technology


  Powerful modern way to generate a library of (protein) ligands and screen them for binding to a selected target molecule
• Phage display process


  1. Generate/obtain a library of genes (one coding for the protein of interest)

  2. Insert genes into a phage library fused to a gene encoding a phage coat protein

  3. Incubate phage with E. coli to facilitate phage replication

  4. Screen phage library by affinity selection (biopanning) to identify the one(s) coding for the protein of interest

  5. Excise the gene coding for the protein of interest and incorporate it into an expression system for large-scale production
• Phage display libraries


  • Immune libraries (from B-lymphocytes of immunized donors)
  • Non-immune libraries (from B-lymphocytes of non-immunized donors)
  • Synthetic immune libraries (engineered non-immune libraries to increase diversity)
• Therapeutic application of monoclonal antibodies

  • Selective interaction with a specific target cell type in the body, dependent on identifying a unique cell surface antigen
  • Antibodies may be conjugated to a radioisotope, drug or toxin to deliver a 'magic bullet' to target cells
• Over 29 antibody-based products had gained marketing approval by 2006, with cancer being the single most significant indication
• Antibiotic


  A substance or compound that kills, or inhibits the growth of, bacteria
• Antibiotics


  • Belong to the broader group of antimicrobial compounds, used to treat infections caused by microorganisms including fungi and protozoa
  • Many are relatively small molecules with a molecular weight less than 2000 Da
• Origin-based classification of antibiotics

  • Natural (produced by microorganisms)
  • Semisynthetic (modified chemically from natural compounds)
  • Synthetic (created through purely synthetic means)
• Effect-based classification of antibiotics

  • Bactericidal (kill bacteria)
  • Bacteriostatic (impair bacterial growth)
• The term "antibiotic" was coined by Selman Waksman in 1942 to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution
• The Kirby-Bauer disk diffusion method tests the susceptibility of Staphylococcus aureus to antibiotics