title: The involvement of serum serotonin levels producing radiation-induced bystander effects for an in vivo assay with fractionated high dose-rate (HDR) brachytherapy.
abstract: OBJECTIVE
  The primary goal of this investigation was to observe whether measurable levels of bystander factor(s) can be detected in esophageal carcinoma patients' urine samples taken after undergoing high dose rate (HDR) intraluminal brachytherapy (ILBT). However, a small pilot study was developed to evaluate whether serotonin [5-Hydroxytryptamine (5-HT)] serum levels play an active role in the mechanisms of radiation-induced bystander effects (RIBE) at high doses.
  
  
  METHODS
  In the present study, a colony-forming in vivo assay was developed and used for the detection of non-targeted effects. Samples of urine were collected from five esophageal carcinoma patients undergoing fractionated HDR-ILBT. To observe whether 5-HT modulates the bystander effect at higher doses, different batches of foetal bovine serum (FBS) and 5-HT were tested on the same urine samples before and after brachytherapy.
  
  
  RESULTS
  Some of our data suggests statistically significant evidence for serotonin playing an active role as a signalling molecule at higher doses when patients underwent HDR-ILBT.
  
  
  CONCLUSIONS
  However, a more thorough investigation, with a larger sample size, is warranted before serotonin can be known to play a role in bystander effects at this particular dose range and treatment regime.
authors: Medical Physics & Applied Radiation Department, McMaster University, Hamilton, ON, Canada. mothers@mcmaster.ca
authors: Christine
authors: C
authors: Pinho
authors: Raimond
authors: R
authors: Wong
authors: Ranjan K
authors: RK
authors: Sur
authors: Joseph E
authors: JE
authors: Hayward
authors: Thomas J
authors: TJ
authors: Farrell
authors: Colin
authors: C
authors: Seymour
authors: Carmel
authors: C
authors: Mothersill
mesh_terms: D000818:Animals; D001918:Brachytherapy; D024201:Bystander Effect / Q000187:drug effects* / Q000528:radiation effects*; D002417:Cattle; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003470:Culture Media / Q000737:chemistry*; D019583:Dose Fractionation, Radiation; D004305:Dose-Response Relationship, Drug; D004938:Esophageal Neoplasms / Q000473:pathology / Q000532:radiotherapy / Q000652:urine; D006801:Humans; D012701:Serotonin / Q000097:blood* / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D012701:Serotonin