20 research outputs found
RENEB intercomparison exercises analyzing micronuclei (Cytokinesis-block Micronucleus Assay)
Purpose: In the framework of the ‘Realizing the European Network of Biodosimetry’ (RENEB) project, two intercomparison exercises were conducted to assess the suitability of an optimized version of the cytokinesis-block micronucleus assay, and to evaluate the capacity of a large laboratory network performing biodosimetry for radiation emergency triages. Twelve European institutions participated in the first exercise, and four non-RENEB labs were added in the second one.
Materials and methods: Irradiated blood samples were shipped to participating labs, whose task was to culture these samples and provide a blind dose estimate. Micronucleus analysis was performed by automated, semi-automated and manual procedures.
Results: The dose estimates provided by network laboratories were in good agreement with true administered doses. The most accurate estimates were reported for low dose points (≤ 0.94 Gy). For higher dose points (≥ 2.7 Gy) a larger variation in estimates was observed, though in the second exercise the number of acceptable estimates increased satisfactorily. Higher accuracy was achieved with the semi-automated method.
Conclusion: The results of the two exercises performed by our network demonstrate that the micronucleus assay is a useful tool for large-scale radiation emergencies, and can be successfully implemented within a large network of laboratories.VII Programa Marco de Investigación y Desarrollo (VIIPM) de la Unión Europea. nº 295513University Development Cooperation "VLIR Own Initiative Programme" enetre Bélgica and Sudáfrica. ZEIN2011PR38
RENEB intercomparisons applying the conventional Dicentric Chromosome Assay (DCA)
Purpose: Two quality controlled inter-laboratory exercises were organized within the EU project ‘Realizing the European Network of Biodosimetry (RENEB)’ to further optimize the dicentric chromosome assay (DCA) and to identify needs for training and harmonization activities within the RENEB network.
Materials and methods: The general study design included blood shipment, sample processing, ana lysis of chromosome aberrations and radiation dose assessment. After manual scoring of dicentric chro mosomes in different cell numbers dose estimations and corresponding 95% confidence intervals were submitted by the participants.
Results: The shipment of blood samples to the partners in the European Community (EU) were per formed successfully. Outside the EU unacceptable delays occurred. The results of the dose estimation demonstrate a very successful classification of the blood samples in medically relevant groups. In com parison to the 1st exercise the 2nd intercomparison showed an improvement in the accuracy of dose estimations especially for the high dose point.
Conclusions: In case of a large-scale radiological incident, the pooling of ressources by networks can enhance the rapid classification of individuals in medically relevant treatment groups based on the DCA. The performance of the RENEB network as a whole has clearly benefited from harmonization processes and specific training activities for the network partners.European Commission (FP7, GA 295513
RENEB accident simulation exercise
Purpose: The RENEB accident exercise was carried out in order to train the RENEB participants in coordinating and managing potentially large data sets that would be generated in case of a major radiological event.
Materials and methods: Each participant was offered the possibility to activate the network by sending an alerting email about a simulated radiation emergency. The same participant had to collect, compile and report capacity, triage categorization and exposure scenario results obtained from all other participants. The exercise was performed over 27 weeks and involved the network consisting of 28 institutes: 21 RENEB members, four candidates and three non-RENEB partners.
Results: The duration of a single exercise never exceeded 10 days, while the response from the assisting laboratories never came later than within half a day. During each week of the exercise, around 4500 samples were reported by all service laboratories (SL) to be examined and 54 scenarios were coherently estimated by all laboratories (the standard deviation from the mean of all SL answers for a given scenario category and a set of data was not larger than 3 patient codes).
Conclusions: Each participant received training in both the role of a reference laboratory (activating the network) and of a service laboratory (responding to an activation request). The procedures in the case of radiological event were successfully established and tested
RENEB intercomparison exercises analyzing micronuclei (Cytokinesis-block Micronucleus Assay)
Purpose: In the framework of the ‘Realizing the European Network of Biodosimetry’ (RENEB) project, two intercomparison exercises were conducted to assess the suitability of an optimized version of the cytokinesis-block micronucleus assay, and to evaluate the capacity of a large laboratory network performing biodosimetry for radiation emergency triages. Twelve European institutions participated in the first exercise, and four non-RENEB labs were added in the second one.
Materials and methods: Irradiated blood samples were shipped to participating labs, whose task was to culture these samples and provide a blind dose estimate. Micronucleus analysis was performed by automated, semi-automated and manual procedures.
Results: The dose estimates provided by network laboratories were in good agreement with true administered doses. The most accurate estimates were reported for low dose points (== 2.7 Gy) a larger variation in estimates was observed, though in the second exercise the number of acceptable estimates increased satisfactorily. Higher accuracy was achieved with the semi-automated method.
Conclusion: The results of the two exercises performed by our network demonstrate that the micronucleus assay is a useful tool for large-scale radiation emergencies, and can be successfully implemented within a large network of laboratories
RENEB intercomparisons applying the conventional Dicentric Chromosome Assay (DCA)
Purpose: Two quality controlled inter-laboratory exercises were organized within the EU project ‘Realizing the European Network of Biodosimetry (RENEB)’ to further optimize the dicentric chromosome assay (DCA) and to identify needs for training and harmonization activities within the RENEB network.
Materials and methods: The general study design included blood shipment, sample processing, analysis of chromosome aberrations and radiation dose assessment. After manual scoring of dicentric chromosomes in different cell numbers dose estimations and corresponding 95% confidence intervals were submitted by the participants.
Results: The shipment of blood samples to the partners in the European Community (EU) were performed successfully. Outside the EU unacceptable delays occurred. The results of the dose estimation demonstrate a very successful classification of the blood samples in medically relevant groups. In comparison to the 1st exercise the 2nd intercomparison showed an improvement in the accuracy of dose estimations especially for the high dose point.
Conclusions: In case of a large-scale radiological incident, the pooling of ressources by networks can enhance the rapid classification of individuals in medically relevant treatment groups based on the DCA. The performance of the RENEB network as a whole has clearly benefited from harmonization processes and specific training activities for the network partners
Variation in radiosensitivities of different individuals to high energy neutrons and 60Cobalt γ-rays
Thesis (MScMedSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Background: The assignment of radiation weighting factors to high energy neutron
sources is important as there is reason to believe that neutron relative biological
effectiveness (RBE) may be related to the inherent radiosensitivity of different
individuals. A study was undertaken to quantify the inherent radiosensitivities of
lymphocytes obtained from different donors to 60Co y-rays and p(66)/Be neutrons.
For this a novel semi-automated image analysis process has been employed. In
addition the responses of lymphocytes with different inherent radiosensitivities have
also been tested using Auger electrons emitted by 123I.
Methods: The RBE of neutrons was determined from dose-response curves for
lymphocytes from different donors. Isolated T-lymphocytes irradiated in vitro were
cultured to induce micronuclei in binucleated cells and micronuclei (MN) formations
numerated using a semi-automated Metafer microscope system. The accuracy in
obtaining dose response curves with this method has been tested by evaluating
dispersion parameters of MN formations in the response to the different treatment
modalities. Differences in the inherent radiosensitivities of cells from different donors
were ascertained using 95 % confidence ellipses. [123I]Iododeoxyuridine was
prepared in a formulation that allows incorporation of 123I into the DNA of
lymphocytes. Micronucleus formations to this treatment were evaluated in
lymphocytes with established differences in inherent radiosensitivities. Results: The image analysis system proved to be consistent in detecting micronuclei
frequencies in binucleated lymphocytes. As a result, differences in the inherent
radiosensitivities of different individuals were distinctive and could be stated at the
95% confidence level. The inter-individual radiosensitivity variations were
considerably smaller for blood cells exposed to high energy neutrons compared to
60Co y-rays. Relative biological effectiveness (RBEM) values between 2 and 13 were determined that are highly correlated with the inherent radioresistance of
lymphocytes obtained from different individuals. As such radiation weighting factors
for high energy neutrons cannot be based on cytogenetic damage determined in
lymphocytes from a single donor. Dispersion parameters for micronuclei formations proved to vary according to ionization density. The variation in RBE with neutron
dose changed according to theoretical considerations and automated image analysis
detection of MN is thus a suitable method to quantify radiation weighting factors.
A clear reduction in the variation in radiosensitivity is noted for lymphocytes exposed
to Auger electrons compared to 60Co y-rays. The effectiveness of Auger electrons
from [123I]IUdR to induce biological damage is demonstrated as the number of disintegrations needed to yield micronuclei formations was found to be more than
two orders of magnitude less than that of other compounds. An increase in the RBE
of Auger electrons with radioresistance can be inferred from these findings and
constitutes a basis for therapeutic gain in treating cells compared to using
radioisotopes emitting low-LET radiation.AFRIKAANSE OPSOMMING: Agtergrond: Die bepaling van straling gewigsfaktore vir hoë energie neutron bronne
is belangrik, aangesien daar rede is om te glo dat die relatiewe biologiese
effektiwiteit (RBE) kan verband hou met die inherente stralings sensitiwiteit van
verskillende individue. Hierdie studie is onderneem om die inherente
radiosensitiwiteit van limfosiete verkry vanaf verskillende skenkers te kwantifiseer na
blootstelling aan 60Co y -strale en p(66)/Be neutrone. Vir hierdie doel is daar van 'n
semi-outomatiese beeldontleding metode gebruik gemaak. Daarbenewens is die
reaksie van limfosiete met vooraf bepaalde inherente radiosensitiwiteite ook getoets
aan die hand van Auger elektrone wat uitgestraal word deur 123I.
Metodiek: Die RBE van neutrone was bepaal uit dosis mikrokerne frekwensie
verwantskappe verkry vir limfosiete. Geïsoleerde T-limfosiete was in vitro bestraal en
gekweek om mikrokerne te vorm in dubbelkernige selle. Die mikrokerne was
gekwantifiseer deur die gebruik van 'n semi-outomatiese Metafer mikroskoop stelsel.
Die akkuraatheid in die verkryging van dosis-effek krommes met hierdie metode is
getoets deur die ontleding van verspreidings parameters van MN vorming in reaksie
op behandeling met die verskillende stralings modaliteite. Verskille in die inherente
stralingsensitiwiteite van die selle van verskillende skenkers was vasgestel deur die
konstruksie van 95 % betroubaarheidsinterval ellipse. [123I]Iododeoxyuridine was ook
berei om 123I in die DNA van limfosiete in te bou. Die mikrokerne vorming op die
behandeling is beoordeel in limfosiete met gevestigde verskille in inherent
radiosensitiwiteite. Resultate: Die beeld analise stelsel bewys om konsekwent te wees in die opsporing
van mikrokerne wat vorm in dubbelkernige limfosiete. Verskille in die inherente
radiosensitiwiteite van verskillende skenkers kon vasgestel word op die 95 %
betroubaarheidsvlak. Die skommeling in inter-individuele stralings sensitiwiteite was
kleiner vir bloed selle blootgestel aan hoë-energie neutrone in vergelyking met 60Co
y-strale. Relatiewe biologiese effektiwiteit (RBEM) waardes tussen 2 en 13 is bepaal
wat sterk verband hou met die inherente radioweerstandbiedendheid van limfosiete
verkry vanaf verskillende persone. As sodanig kan straling gewigsfaktore vir hoë energie neutrone nie gebaseer word op sitogenetiese skade in limfosiete van 'n
enkele skenker nie. Verspreidings parameters vir mikrokern vorming het gewissel as
‘n funksie van ionisasiedigtheid van die straling. Die verandering in RBE met neutron
dosis verloop volgens teoretiese oorwegings en die semi-outomatiese
beeldontledings metode om mikrokerne op te spoor is dus geskik om stralings
gewigsfaktore te kwantifiseer.
'n Duidelike afname in die verandering in die stralingsensitiwiteite is waargeneem vir
limfosiete blootgestel aan Auger elektrone in vergelyking met 60Co y-strale. Die hoë
doeltreffendheid van Auger elektrone afkomstig van [123I]IUdR om biologiese skade
te veroorsaak, word weerspieël deur die feit dat die getal disintegrasies wat nodig is
om mikrokerne te vorm meer as twee ordes grootte minder is as dié van ander
verbindings. 'n Toename in die RBE van Auger elektrone in selle wat
radioweerstandbiedend is kan afgelei word uit hierdie bevindinge. Dit vorm 'n basis
vir terapeutiese wins in die behandeling van selle in vergelyking met die gebruik van
radio-isotope wat lae ionisasie digthede tot stand bring
Induction and disappearance of γH2AX foci and formation of micronuclei after exposure of human lymphocytes to 60Co γ-rays and p(66)+Be(40) neutrons
Purpose: To investigate both the formation of micronuclei (MN) and the induction and subsequent loss of phosphorylated histone H2AX foci (γH2AX foci) after in vitro exposure of human lymphocytes to either 60Co γ-rays or p(66)+Be(40) neutrons.
Materials and methods: MN dose response (DR) curves were obtained by exposing isolated lymphocytes of 10 different donors to doses ranging from 0 to 4 Gy γ-rays or 0 to 2 Gy neutrons. Also, γH2AX foci DR curves were obtained following exposure to doses ranging from 0 to 0.5 Gy of either γ-rays or neutrons. Foci kinetics for lymphocytes for a single donor exposed to 0.5 Gy γ-rays or neutrons were studied up to 24 hours post-irradiation.
Results: Micronuclei yields following neutron exposure were consistently higher compared to that from 60Co γ-rays. All MN yields were over-dispersed compared to a Poisson distribution. Over-dispersion was higher after neutron irradiation for all doses > 0.1 Gy. Up to 4 hours post-irradiation lower yields of neutron-induced γH2AX foci were observed. Between 4 and 24 hours the numbers of foci from neutrons were consistently higher than that from γ-rays. The half-live of foci disappearance is only marginally longer for neutrons compared to that from γ-rays. Foci formations were more likely to be over-dispersed for neutron irradiations.
Conclusion: Although neutrons are more effective to induce MN, the absolute number of induced γH2AX foci are less at first compared to γ-rays. With time neutron-induced foci are more persistent. These findings are helpful for using γH2AX foci in biodosimetry and to understand the repair of neutron-induced cellular damage