NATIONAL DOSE REGISTER IN FRANCE WITHIN THE NATIONAL INFORMATION SYSTEM SISERI.

Over the past decade, France has developed an electronic dose register at national level called SISERI. Institute for Radiological Protection and Nuclear Safety is in charge of the management of this information system. Besides the main purpose of being a central register of any doses measured for the individual dosimetric monitoring of all exposed workers, SISERI has been developed so as to constitute a tool for occupational physicians and radiation protection officers allowing access in real-time to the results of the individual monitoring. The SISERI information system centralises, verifies and keeps the records of all personal dosimetric results of the 370 000 workers annually monitored in France. Moreover, since the publication of a new order in 2013, employers shall declare any new workers in SISERI before the beginning of their occupation and they shall upload data concerning in particular the activity field/sector and the occupation of each worker. The enforcement of this new order is going to enrich the individual dosimetric information stored in SISERI. Thus, it is expected that more precise and accurate statistics on occupational exposure to ionising radiation in France will be established in the next few years.

Occupational external exposure to ionising radiation in France (2005-2011).

The Institute for Radiological Protection and Nuclear Safety (IRSN) produces the French annual report on occupational exposure to ionising radiation, collecting all national data and aggregating the results according to a unique activity classification expected to be shared by all involved in personal dosimetric monitoring (employers, external dosimetry services and IRSN). Nearly 344,000 monitored workers were counted in France in 2011, with a collective dose of 64.24 man.Sv. The average annual dose (as calculated over the number of measurably exposed workers) differed among the main activity fields: 0.54 mSv in medical and veterinary activities, 1.18 mSv in the nuclear field, 1.60 mSv in non-nuclear industry and 0.47 mSv in research activities. Because of improved knowledge about worker activities, the results for year 2011 are detailed per activity sectors in each field. Lasting limitations prevent from having complete and reliable worker activity information. Solutions are considered to reduce the inaccuracy in the annually published statistics. The evolution of occupational external exposure to ionising radiation from 2005 to 2011 in France is then presented for the main activity fields.

Population exposure to ionizing radiation from medical examinations in France.

This study was carried out to update data concerning both the nature and the frequency of X-ray diagnostic procedures and to reassess the associated per caput effective dose in France, given that the only nationwide survey was carried out over 15 years ago. Relevant data concerning examinations in conventional radiology, computed tomography, interventional radiology and nuclear medicine were obtained for the year 2002 from two main sources: the main health insurance records for private practices and the statistics of healthcare establishments on hospital activity. Doses associated with different types of examination were obtained from the diagnostic reference levels (DRL) campaign, together with data from the European Commission and from the Health Protection Agency in the UK. The results show that between 55.4 and 65.9 million procedures were performed in 2002 in conventional radiology (one-third for dental) and between 4.2 and 6 million in computed tomography. There were 850,000 and 900,000 procedures in nuclear medicine and interventional radiology respectively. Conventional radiology accounts for 90% of the total number of procedures but only 37% of the collective dose, whereas examinations in computed tomography account for 8% of total examinations but 39% of the collective dose. Examinations in nuclear medicine and interventional radiology account for 2% of procedures but 7% and 17% of the collective dose respectively. Finally, the per caput effective dose in 2002 was between 0.66 and 0.83 mSv.

Screening of a large panel of gastrointestinal peptide plasma levels is not adapted for the evaluation of digestive damage following irradiation.

The aim of this study was to assess the potential of gastrointestinal peptide plasma levels as biomarkers of radiation-induced digestive tract damage. To this end, plasma levels of substance P, GRP, motilin, PYY, somatostatin-28, gastrin, and neurotensin were followed for up to 5 days in pigs after a 16-Gy whole-body X-irradiation, completed by a histopathological study performed at 5 days. Each peptide gave a specific response to irradiation. The plasma levels of GRP and substance P were not modified by irradiation exposure; neither were those of motilin and PYY. Concerning gastrin, a 2-3-fold increase of plasma concentration was observed in pig, which presented the most important histological alterations of the stomach. The plasma levels of somatostatin, unchanged from 1 to 4 days after irradiation, was also increased by 130% at 5 days. In contrast, a diminution of neurotensin plasma levels was noted, firstly at 1 day (-88%), and from 3 days after exposure (-50%). The present study suggested that changes in gastrin and neurotensin plasma levels were associated with structural alterations of the stomach and ileum, respectively, indicating that they may be relevant biological indicators of radiation-induced digestive damage to these segments.

Alteration of the enterohepatic recirculation of bile acids in rats after exposure to ionizing radiation.

The aim of this work was to study acute alterations of the enterohepatic recirculation (EHR) of bile acids 3 days after an 8-Gy radiation exposure in vivo in the rat by a washout technique. Using this technique in association with HPLC analysis, the EHR of the major individual bile acids was determined in control and irradiated animals. Ex vivo ileal taurocholate absorption was also studied in Ussing chambers. Major hepatic enzyme activities involved in bile acid synthesis were also measured. Measurements of bile acid intestinal content and intestinal absorption efficiency calculation from washout showed reduced intestinal absorption with significant differences from one bile acid to another: absorption of taurocholate and tauromuricholate was decreased, whereas absorption of the more hydrophobic taurochenodeoxycholate was increased, suggesting that intestinal passive diffusion was enhanced, whereas ileal active transport might be reduced. Basal hepatic secretion was increased only for taurocholate, in accordance with the marked increase of CYP8B1 activity in the liver. The results are clearly demonstrate that concomitantly with radiation-induced intestinal bile acid malabsorption, hepatic bile acid synthesis and secretion are also changed. A current working model for pathophysiological changes in enterohepatic recycling after irradiation is thus proposed.

Modified bile acid profiles in mixed neutron and gamma-irradiated pigs.

PURPOSE: To determine the effect of mixed neutron and gamma-irradiation on the bile acid pool, which may be a key factor in radiation-induced diarrhoea. MATERIALS AND METHODS: The bile duct of pigs was catheterized to derive bile over several experimental weeks, both before and after a 5.9 Gy neutron and gamma-irradiation. After measurement of the volume and sampling, bile was returned to the pig via a duodenal catheter. Samples of bile were analysed by HPLC for their individual and total bile acid content. Blood samples were also collected for total bile acid determination. RESULTS: Bile flow was significantly decreased during the first 24h and after the fifth day post-irradiation. Whereas total bile acid concentration in bile was not altered, profiles of individual bile acids were significantly altered as early as the first post-irradiation day. Such modifications in these profiles resulted in a change of the properties of the bile acid pool. An increased proportion of dihydroxylated bile acids known to be more deleterious for the intestine was observed. CONCLUSIONS: Neutron and gamma-irradiation leads to modifications of bile acid profiles, which may partly explain radiation-induced diarrhoea by a coherent physiopathological mechanism.

Whole-body gamma irradiation modifies bile composition in the pig.

The effects of 6 Gy whole-body 60Co gamma irradiation on bile composition in pigs were studied to determine possible alterations in the quality of the bile, which may be a determining factor in diarrhea as well as nutrient malabsorption, which classically occurs after irradiation. The bile duct of pigs was catheterized to allow a total and continuous deviation of bile over several weeks, before and after irradiation. After measurement of the volume and sampling, bile was returned to the animal via a duodenal catheter. Bile samples were then analyzed for cholesterol, phospholipid and total bile acid content. Individual bile acids were quantified by HPLC analysis. Bile flow was significantly decreased during the first 24 h and after the fifth day postirradiation. Whereas cholesterol, phospholipid and total bile acid concentrations were not altered, profiles of individual bile acids were modified significantly as early as the first day postirradiation. Moreover, the change of these profiles with time was specific for each bile acid. Such modifications in bile acid profiles resulted in a change in the properties of the bile acid pool in an increased proportion of dihydroxylated bile acids known to interfere with gut functions, and it is reasonable to suggest that radiation-induced changes in bile acid profiles may be involved in radiation-induced gastrointestinal disorders.

Characterization and kinetics of gastric emptying of peptides derived from milk proteins in the preruminant calf.

The gastric emptying kinetics of peptides derived from milk protein were studied in vivo in preruminant calves by collecting and characterizing the whole effluent leaving the stomach for 12 h after ingestion of crude skim milk. Peptides were isolated by reversed-phase HPLC and identified. Particular attention was paid to biologically active peptides and to peptides that could be precursors of biologically active sequences. A gastrin inhibitor, the caseinomacropeptide, was emptied from the stomach only during the first 0.5 h of digestion and rapidly hydrolysed. Precursors of immunostimulatory peptides from alpha s1- and beta-caseins were emptied throughout digestion in the gastric effluent. A precursor of beta-casomorphins (peptide 58-93 of beta-casein) was emptied from the stomach 3.5 h after the meal when it was taken on an empty stomach. From this precursor, peptides that may be resistant to hydrolysis by intestinal peptidase were obtained after in vitro hydrolysis by pancreatic enzymes. A phosphopeptide (fragment 110-142 of alpha s1-casein) was also found in digesta after a few hours of digestion. When the meal was not taken on an empty stomach, these peptides were emptied in the first digesta at a low concentration. The potential activity of these peptides is discussed. The results support the hypothesis that active sequences could still be present in the gut after the action of pancreatic enzymes.

Immobilized Fe3+ affinity chromatographic isolation of phosphopeptides.

Immobilized Fe3+ affinity chromatography is suggested as a means of concentrating phosphopeptides that are present in too low a proportion in a complex mixture to be purified by a single-step method. A high-performance liquid chromatographic system and a chelating Superose HR 10/2 column were used. The chromatographic conditions were optimized using a tryptic hydrolysate of whole casein. The unbound fractions did not contain any phosphorylated peptide. All caseinophosphopeptides were retained. Only four other strongly basic peptides were also retained. The quantitative accuracy of the method was evaluated. This method allowed the isolation of phosphopeptides in gastric effluents of calves fed with milk.