Global variance-based SA has been for the first time applied to the MIRD schema for internal dose calculation. Our findings suggest that uncertainties in computed organ doses can be substantially reduced by performing an accurate determination of TIACs in the source regions, accompanied by the estimation of individual source region masses along with the usage of an appropriate blood distribution in a patient's body and, in a few cases, the cross-fire SAFs from proximal source regions.

The antiatherogenic properties of high density lipoproteins (HDLs) are thought to reside in their involvement hi the reverse cholesterol transport pathway. Specific HDL-binding proteins could play a key role in this process. Two HDL-binding proteins of approximately SKI and 180 kd were identified in porcine liver by ligand blotting and were purified to apparent homogeneity by a combination of protein extraction, DEAE-cellulose chromatography, Con A-Sepharose chromatography, and preparative sodium dodecyl sulfate-poJyacryiamide gel electrophoresis. Binding of IZ5 I-HDL by these proteins could be actively competed for by unlabeled HDL but not by low density lipoprotein. Polyclonal antisera have been raised against these two proteins. Each antiserum recognized only one of the HDL-binding proteins, indicating that they are not immunologically related. Moreover, striking differences in localization were observed in Immunohistochemical studies. The 90-kd protein is located within the hepatocellular plates, while the 180-kd protein is present along the lining of the sinusoids. These results suggest functional differences between the two HDL-binding proteins described. ( This hypothesis is based on epidemiological data, which show a strong inverse correlation between plasma HDL cholesterol level and the prevalence of CHD, 2 -4 and on intervention studies, which indicate that elevation of HDL cholesterol level is effective in the primary prevention of CHD. 5 The antiatherogenic properties of HDL are probably based on the ability of HDL to promote efflux of cholesterol from peripheral cells and to deliver it to the liver for excretion, a concept termed reverse cholesterol transport. 6 -9 The binding characteristics of HDL to cultured cells and to purified plasma membrane fractions strongly suggest the existence of a specific, high-affinity HDL receptor.10 -13 Because such a receptor could have a key position in the process of reverse cholesterol transport, several groups have sought to identify HDL-binding proteins by using ligand blot studies. Their results differ in the molecular masses of HDL-binding proteins found, 14 -19 which may be attributable to species and/or tissue specificity.It is conceivable that in the reverse cholesterol transport pathway, the tissues involved in cholesterol efflux (peripheral tissues) have a different HDL metabolism than the liver, which is involved in cholesterol clearance. A peripheral HDL-binding protein has been described and characterized by Oram and coworkers. 17-20 * 21 We investigated HDL-binding proteins in the liver. In the present study, two HDL-binding proteins in porcine liver are described. Their histological localization is notably different, presumably reflecting their involvement in different steps in the reverse cholesterol transport pathway. Methods LipoproteinsLow density lipoproteins (LDLs) (d= 1.019-1.063 g/ml) and HDL (d= 1.063-1.21 g/ml) were isolated from human plasma of healthy volunteers by sequential ultracentrifugation. 22 The same procedure was followed fo...

Gastroschisis was investigated experimentally as well as clinically. An experimental model developed in the chick embryo demonstrated that the characteristic picture of gastroschisis evolved only if the herniated bowel was exposed to urine components in the allantoic fluid. Remarkable similarities were revealed on comparing changes in human amniotic fluid composition (from 30th week) with changes in chicken allantoic fluid composition (from 15th day of incubation). These changes correlate with progressive fibrotic coating of the exposed bowel loops leading to the characteristic picture of gastroschisis. No fibrous coating was found in human foetuses with a gestational age under 30 weeks, while investigation of these foetuses did confirm that gastroschisis itself occurs at an early developmental stage (6th-8th week). No primary structural defects were found in the nervous system of the bowel wall neither in the experimental gastroschisis model nor in the human cases investigated. The postoperative delay in intestinal motility affecting some gastroschisis patients was found to be secondary to multifocal ischaemic damage of the bowel wall.

Background The exposure of a pregnant woman to X-rays is an event that can cause uncertainty for all concerned. This review provides guidance on how to assess such a situation and how to determine the dose to the unborn child. In general, the use of X-rays in pregnant women in radiology should be avoided. If possible, alternatives should be used, or examinations postponed to a time after the pregnancy. This review gives a summary of the procedure for determining the radiation exposure of a pregnant woman. Method Based on the previous report of 2002 and the literature on prenatal radiation exposure published thereafter, the DGMP/DRG report on the procedure for the assessment of prenatal radiation exposure was adapted to the current state of science and technology. Results Typically, only relatively low radiation exposures of less than 20 mSv occur for the unborn child in X-ray diagnostics in the vast majority of cases. At these dose level the additional risk of damage to the embryo or fetus caused by the radiation is low and therefore only a rough conservative estimate using tabulated values are made. Only in a few types of examination (CT and interventional radiology) higher doses values might occur in the uterus. Instead of dose estimates (step 1 in the two-step model) in these cases the calculation of dose (step 2) are required and further action by the physician may be necessary. Conclusions During the assessment, it is useful to initially use simple conservative estimation procedures to quickly determine whether a case falls into this large group less than 20 mSv, where there is a very low risk to the unborn child. If this is the case, the pregnant woman should be informed immediately by the doctor who performed the examination/treatment. This avoids a psychological burden on the patient. The DGMP/DRG report suggests a relatively simple, clearly structured procedure with advantages for all parties involved (physician, medical physics experts, MTRA and patient). Key points:  Citation Format

Background: Given the increasing clinical use of PET/MRI, potential risks to patients from simultaneous exposure to ionising radiation and (electro)magnetic fields should be thoroughly investigated as a precaution. With this aim, the genotoxic potential of 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) and a strong static magnetic field (SMF) were evaluated both in isolation and in combination using the γH2AX assay detecting double-strand breaks in lymphocyte DNA. Methods: Thirty-two healthy young volunteers allocated to three study arms were exposed to [ 18 F]FDG alone, to a 3-T SMF alone or to both combined over 60 min at a PET/CT or a PET/MRI system. Blood samples taken after in vivo exposure were incubated up to 60 min to extend the irradiation of blood by residual [ 18 F]FDG within the samples and the time to monitor the γH2AX response. Absorbed doses to lymphocytes delivered in vivo and in vitro were estimated individually for each volunteer exposed to [ 18 F]FDG. γH2AX foci were scored automatically by immunofluorescence microscopy. Results: Absorbed doses to lymphocytes exposed over 60 to 120 min to [ 18 F]FDG varied between 1.5 and 3.3 mGy. In this time interval, the radiotracer caused a significant median relative increase of 28% in the rate of lymphocytes with at least one γH2AX focus relative to the background rate (p = 0.01), but not the SMF alone (p = 0.47). Simultaneous application of both agents did not result in a significant synergistic or antagonistic outcome (p = 0.91). Conclusion: There is no evidence of a synergism between [ 18 F]FDG and the SMF that may be of relevance for risk assessment of PET/MRI.