title: In vitro study of the optimum volume ratio of activator to adhesive in gelatin-resorcin-formalin glue.
abstract: OBJECTIVE
  Excessive use of activator (formaldehyde + glutaraldehyde) may cause late complications after use of gelatin-resorcin-formalin (GRF) glue during surgery. The goal of the study was to define the appropriate ratio of activator to adhesive and to establish an approach for accurate control of this ratio.
  
  
  METHODS
  The relation between adhesive force and the activator/adhesive ratio was studied by attaching two sheets of equine pericardium using GRF glue, with ratios from 1: 50 to 1: 2. The amount of activator was measured per drip from the needle in the GRF glue kit and other needles (27, 25, 23, 22, and 21 gauge).
  
  
  RESULTS
  The adhesive force was about 400 gram-weight (gw) for activator/adhesive ratios from 1: 50 to 1: 20. This force showed a significant increase to 1317 ± 462 gw for a ratio of 1: 10 compared to the force at a ratio 1: 20 (P = 0.0069) but did not increase significantly for ratios above 1: 10. The activator volume was 12.5 μl in one drip from the needle in the GRF glue kit and 4.3 μl in one drip from the 27-gauge needle. Therefore, the 27-gauge needle is suitable for measuring the activator volume.
  
  
  CONCLUSIONS
  In vitro, an activator at a ratio of one-tenth the volume of the adhesive provides approximately maximum force; any more activator is residual and potentially harmful. Measurement of the activator volume using a 27-gauge needle and the adhesive volume using a syringe is recommended to control the ratio accurately.
authors.affiliation: Division of Cardiovascular Surgery, National Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. isodas@ndmc.ac.jp
authors.forename: Susumu
authors.initials: S
authors.lastname: Isoda
authors.forename: Tamizo
authors.initials: T
authors.lastname: Kimura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mashiko
authors.forename: Shingo
authors.initials: S
authors.lastname: Nakamura
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Maehara
mesh_terms: D000268:Adhesiveness; D000818:Animals; D004338:Drug Combinations; D004867:Equipment Design; D005557:Formaldehyde / Q000737:chemistry / Q000494:pharmacology*; D005780:Gelatin / Q000737:chemistry / Q000494:pharmacology*; D006736:Horses; D008422:Materials Testing; D009339:Needles; D010496:Pericardium / Q000187:drug effects*; D012118:Resorcinols / Q000737:chemistry / Q000494:pharmacology*; D013314:Stress, Mechanical; D013594:Syringes; D014014:Tissue Adhesives / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004338:Drug Combinations; D012118:Resorcinols; D014014:Tissue Adhesives; C027813:gelatin-resorcinol-formaldehyde tissue adhesive; D005557:Formaldehyde; D005780:Gelatin