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Biological dosimetry, which determines the absorbed dose of radiation by measuring radiation-induced variation of various biological parameters, can help to assess radiation damage in a given patient and evaluate his or her sensitivity to radiation. The chromosomal aberration count in circulating lymphocytes is considered to be the most specific as well as the most sensitive method for measuring radiation exposure; as such, it is used in forensic medicine. Evaluation of radiation exposure requires setting up reference curves for each type of radiation. In nuclear medicine, exposure is currently calculated mathematically and not by considering its biological consequences. Biological dosimetry uses a more realistic approach towards the consequences of radiations received during an examination in nuclear medicine. The aim of the study was to evaluate the long-term consequences of the in vivo administration of 99mTc-sodium oxidronate (HDP), on the basis of the induction of stable chromosomal aberrations. Stable aberrations were scored before and after administration of the 99mTc-labelled radiopharmaceutical. First, a specific relationship between the dose of 99mTc and the frequency ofstable chromosomal aberrations was established in vitro to estimate whole-body dose. Six volunteer patients were included in the study. Blood samples were obtained before and 6 and/or 24 hours after 99mTc-HDP administration. Stable chromosomal aberrations in irradiated lymphocytes were scored using fluorescence in situ hybridization using human whole-chromosome-specific DNA probes for chromosomes 2, 4 and 12. Analysis of the in vitro data shows that the number of translocations has a quadratic linear relationship with the administered dose. Systemic administration of 99mTc-HDP at routine activity did not induce additional early translocations over the background level. Translocation scoring performed months or even years after the administration of 99mTc-HDP could be necessary to rule out side effects on bone marrow stem cells.

Dans certaines conditions de températures basses peu avant la méiose, on observe une réduction de la production de pollen et de la nouaison chez le blé. Ces phénomènes sont particulièrement manifestes chez les lignées demi-naines issues de Norin 10, les descendants du géniteur VPM issus d’hybridations interspécifiques et surtout chez les hybrides entre ces 2 groupes. Nous ayons fait l’hypothèse que des irrégularités méiotiques pouvaient expliquer cette situation. Une analyse du comportement méiotique, de la fertilité pollinique et de la nouaison a été réalisée sur 4 lignées : « Maris Freeman » (T), «(Champlein x Aronde) 68 » (C), « VPM 1.1.1.2.R4 » (V) et « Naïnari 60S » (U) ; sur les hybrides F1 entre ces lignées, sur certains rétrocroisements et sur des plantes F2 du croisement (VU). Nous avons défini un critère de mesure du déficit de fertilité de l’épi, le taux de nouaison, qui est la probabilité d’obtenir un grain dans les 2 premières fleurs de l’épillet. L’observation des 4 premiers épillets fertiles de la base de l’épi semble être suffisante pour réaliser cette estimation. Une corrélation nette a pu être mise en évidence entre le pourcentage de grains de pollen anormaux et le taux de nouaison. Certains génotypes ont des taux de nouaison faibles comme T et surtout V. Ils produisent des F1 dont le taux de nouaison dépend du partenaire avec lequel ils sont combinés. Nous observons un taux de nouaison plus faible en moyenne en F2 qu’en F1. L’effet du cytoplasme semble faible. Le comportement méiotique des hybrides est moins régulier que celui des parents. Un excès d’univalents et de multivalents traduit qu’ 1 ou 2 translocations réciproques importantes différencient les parents mis en présence. Les irrégularités méiotiques importantes induisent toujours une baisse du taux de nouaison, cependant une méiose régulière ne conduit pas obligatoirement à un taux de nouaison élevé. Les défauts d’association des chromosomes en métaphase 1 n’expliquent donc que très partiellement la réduction de nouaison observée., After a cold spring, a decrease in pollen production and seed set was observed in wheat. These phenomena were most marked with semi-dwarf lines derived from Norin 10, progenies of interspecific crosses and particularly among the hybrids between these two groups. Irregular meiotic behaviour could possibly explain this situation. Meiotic behaviour, pollen fertility and seed set were analysed on 4 lines : "Maris Freeman" (T), "(Champlein x Aronde) 68" (C), "VPM 1.1.1.2.R4" (V) and "Nainari 60S" (U), on the Fl hybrids between these lines. some back-cross plants and F2 plants from the (VU) cross. Lack of fertility was defined as the level of seed set corresponding to a probability of one grain in the first 2 florets of the spikelet. Observation of the first 4 spikelets at the base of the spike gave a good estimate of the level of fertility. A correlation was found between the percentage of abnormal pollen and seed set level. Some genotypes showed a seed set level as low as T and most as low as V. The seed set of their Fl depended on the other parent. On average, the seed set level was lower in F2 than in F1. The cytoplasmic effect seemed to be low. The meiotic behaviour of the hybrids was less regular than that of the parents. Excess of univalents and multivalents showed that one or two reciprocal translocations existed between the parents. Irregular meiosis always induced a decrease in seed set level ; nevertheless regular meiosis did not always indicate a high seed set level. Lack of chromosome pairing at metaphase I was not sufficent to explain the decrease of seed set.