title: Chromosomal radiosensitivity in secondary-progressive multiple sclerosis patients.
abstract: OBJECTIVE
  To investigate chromosomal radiosensitivity of secondary progressive (SP) multiple sclerosis (MS) patients in comparison to a group of healthy individuals.
  
  
  METHODS
  Chromosomal radiosensitivity was assessed in vitro with the G2 assay and the G0-micronucleus (MN) assay. For the G2 assay phytohaemagglutinin (PHA) stimulated blood cultures were irradiated with a dose of 0.4 Gy 60Co gamma rays in the G2 phase of the cell cycle. For the MN assay unstimulated diluted blood samples were exposed to 3.5 Gy 60Co gamma rays delivered at a high dose-rate (HDR = 1 Gy/min) or low dose-rate (LDR = 4 mGy/min).
  
  
  RESULTS
  No significant differences in the number of chromatid breaks were observed between MS patients and healthy individuals. With the G0-MN assay a higher spontaneous MN yield was found in MS patients. At HDR irradiation no significant differences were shown, while at LDR irradiation, MS patients were found less sensitive than healthy controls. The dose-rate sparing index was higher for MS patients, pointing to a better repair capacity.
  
  
  CONCLUSIONS
  MS patients are not characterised by an enhanced in vitro chromosomal radiosensitivity. The radioresistant response, which was only observed with the MN assay after LDR irradiation, may point to an adaptive response induced by in vivo oxidative stress in SPMS patients.
authors.affiliation: Department of Environmental and Life Physics, National Institute for Physics and Nuclear Engineering Horia Hulubei, 407 Atomistilor St., R-76900 Bucharest-Magurele, Romania.
authors.forename: Ileana
authors.initials: I
authors.lastname: Petcu
authors.forename: Diana
authors.initials: D
authors.lastname: Savu
authors.forename: Anne
authors.initials: A
authors.lastname: Vral
authors.forename: Hubert
authors.initials: H
authors.lastname: Thierens
authors.forename: Guy
authors.initials: G
authors.lastname: Nagels
authors.forename: Leo
authors.initials: L
authors.lastname: De Ridder
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000528:radiation effects; D002869:Chromosome Aberrations / Q000528:radiation effects*; D002877:Chromosomes, Human / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000097:blood* / Q000235:genetics*; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000528:radiation effects