title: Short-term bioeffects of an infrared pulsed laser device on burned rat skin monitored by transverse relaxation times (NMR).
abstract: OBJECTIVE
  The aim of this study was to determine whether the application of an infrared pulsed laser device (IPLD) on the burned skin of rats induced significant changes in the water dynamics of the burned tissues as measured by nuclear magnetic resonance (NMR) at a proton frequency of 90 MHz by using transverse relaxation times (T2, I/T2).
  
  
  METHODS
  Seven groups (GI-GVII), each consisting of four albino rats (Sprague-Dawley), of 12-14 weeks of age were used in the experiment. Rats in GI-GVI were anesthetized and burned with a hot tip. GI, GIII, GV were not irradiated. GII, GIV, GVI were irradiated at 0 hours; 0 and 24 hours; and 0, 24, and 48 hours, respectively. Rats in GVII served as controls and were neither burned nor irradiated. Samples from all groups were obtained and monitored by NMR by using transverse relaxation times (T2 and 1/T2). An unpaired Student's t-test and a one-way analysis of variance (ANOVA I) were preformed on the mean values obtained (T2, 1/T2). The statistical design was chosen to give a 95% power of contrast 1-beta (1/T2). The modulated beam of the IPLD used is composed of two superposed waves; a carrier wave (3 MHz), and a drive force wave in the near infrared (904 nm, f = 1014 Hz). A dose of 1.5 x 10(3) J/M2 per session was applied by placing the IPLD directly over the burned tissue by using a top-hat distribution.
  
  
  RESULTS
  The results of a t-test on the T2 and 1/T2 values did not show statistically significant differences at 0 and 24 hours between the irradiated groups, the nonirradiated groups, and the nonburned nonirradiated (control) group. Nonetheless, at 48 hours after the burn, we found a statistically significant difference in the 1/T2 values for the irradiated specimens compared with the nonirradiated specimens and the control group. Furthermore, the variance of the 1/T2 values as a function of time showed a tendency to decrease significantly only for the irradiated specimens.
  
  
  CONCLUSIONS
  These findings show possible effects on the water dynamics of burned rat tissue in a short term as a result of the IPLD's application.
authors: Foundation for Interdisciplinary Research and Development Fundalas, Caracas, Venezuela. fundalas@hotmail.com
authors: L A
authors: LA
authors: Santana-Blank
authors: E
authors: E
authors: Rodríguez-Santana
authors: D
authors: D
authors: Scott-Algara
authors: M
authors: M
authors: Hunger
authors: K E
authors: KE
authors: Santana-Rodríguez
authors: R
authors: R
authors: Orellana
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism*; D002056:Burns / Q000378:metabolism / Q000532:radiotherapy*; D053685:Laser Therapy; D009682:Magnetic Resonance Spectroscopy; D051381:Rats; D017207:Rats, Sprague-Dawley