Effect of Drinking Zn-DTPA on 238-Pu and 241-Am in rat bones

Conclusion Substantial fractions of²³⁸Pu and²⁴¹Am deposits were removed from the bones of growing rats by addition of Zn-DTPA to drinking water. The effect of treatment in various parts of long bones was different, obviously due to differences in the bone growth and remodelling.     

Effect of 241-Am on bone fibroblasts

Conclusion The results indicate that the fibroblast colony forming cell is radiosensitive for-irradiation from the radionuclide^241Am. This implies that the CFU-f must be localized within the range of the-rays.The quantitative response of the CFU-f on the-irradiation does not allow to draw the firm conclusion that the CFU-f is a possible target cell for bone-cancer induction. Only radioresistant CFU-f keep the potentiality of bone-cancer induction. This leads to the hypothesis, that the radio-resistant (and even increasing) CFU-f population in femur shaft, distal, and proximal epiphyses and sternum could be most interesting to follow and to check for qualitative changes that could give information about the toxicological properties of²⁴¹Am in connection with the carcinogenic induction in this cell line.     

241-Am in the beagle skeleton: Microdistribution and local dosimetry

Conclusions Specific surface activities and dose rates to the 0–10 µm band are not very different in the types of bones investigated but there is a positive correlation between these parameters and bone turnover. Dose rates in deep marrow differ widely between individual types of bone but no tendency towards star formation could be detected in autoradiographs. Average burial depths for surface labels are comparable in the various types of bone (5.3–8.6 µm). Morphometric parameters indicate that radiation damage caused alterations of bone structure.     

Quantitative and morphometric parameters determining the development of the supraoptic nucleus in the albino rat

The principal part of the supraoptic nucleus (SON) of the rat presents specific developmental factors. The parameters selected for their evaluation were volume of the SON, neuronal number and neuronal density. White Wistar rats of the age of 18, 19, 20, 22 and 23 intrauterine days, 15 days and 1, 3, 6, 12, 18 and 30 months were chosen for this study. The rat brains were fixed, cut into 10-micron-thick sections and stained with hematoxylin-eosin. The different measurements were carried out with a semiautomatic IBAS I image analyzer. In all stages of the rat life, an increase in volume and a decrease in neuronal density per surface unit could be observed, but there was a difference in the dynamics of these changes depending on the stage in which the parameters were determined. There were two periods in the life of the rat in which neuronal death was very significant. The first was between the embryonic and juvenile stage and the second between the adult and senile stage. The increase in the volume influences predominantly the value of neuronal density.     

Reducing the radiation dose from inhaled americium-241 using continuously administered DTPA therapy

Accelerating the removal of a radionuclide from the body of a contaminated individual is the only available approach to decreasing the radiation dose from such exposures. In this study, continuous infusion of a chelating agent, DTPA, was given to dogs that had inhaled a moderately soluble aerosol, 241 AmO2, not only to accelerate clearance of the radionuclide from the lung but also to prevent its deposition in liver and bone. Treatment was begun with an intravenous injection of CaDTPA 1 h after exposure, and was continued for 64 days after exposure by implanting subcutaneously osmotic pumps containing ZnDTPA at 1 day after exposure. The results showed that the infusion therapy was effective in blocking the translocation of 99.5 per cent of the 241Am that would have been deposited in liver, and 98.3 per cent of the 241Am that would have been deposited in bone. This result was significantly better than the result achieved using repeated intravenous injections of DTPA, the method of treatment in current use for actinide contamination cases.     

Influence of progesterone administration in early stage of development on morphometric parameters of the rat uterus

The aim of this study was to evaluate the effects of single injection of 0.5 mg progesterone in neonatal stage of development on morphometric parameters of the adult rat uterus. The results showed that there were no changes ofendometrial morphometry in respect to oestrous cycle in neonatal treated rats. Neonatal administration of progesterone decreased the myometrium thickness in oestrus and dioestrums owing to circular muscle layer, and disturbed sex steroids secretion during the oestrous cycle. These data suggest that neonatal administration progesterone reduces the endometrium sensitivity to sex steroids and produces the myometrium atrophy.     

Long-term distribution of 239-Pu, 241-Am,and 233-U in the various bones of the skeleton of adult rats

Conclusions The macrodistribution of the bone surface seekers plutonium and americium and of the bone volume seeker uranium has been analysed in different bones of the skeleton of adult male and female rats under identical laboratory conditions. Whereas the relative concentration differs in a wide range between the different bones and the different nuclides there is the general tendency with time to reach a mean concentration for the whole skeleton. Whereas the retention of 239-Pu and 241-Am is similar in the skeleton with a biological half-life of more than 1 year, 233-U shows a rapid decrease of the nuclide content with a biological half-life of 80 days in male and 140 days in female rats, respectively.     

Densitometric, morphometric and mechanical distributions in the human proximal femur

With the prevalent use of DXA-measured BMD to assess pathologic hip fractures and its recently reported lack of reliability to predict fracture or account for efficacy of anti-resorptive therapy, it is reasonable to assess whether variations in the primary and secondary tensile and compressive trabecular microstructure can account for variations in proximal femur strength in comparison to DXA-measured BMD. To that end, microstructural and densitometric measures of trabecular bone specimens, from discrete sites within the proximal femur, were correlated with their mechanical properties. We hypothesize that accounting for regional variations in trabecular microstructure will improve predictions of proximal femur strength and stiffness compared to bone density measured by DXA. Forty-seven samples (seven donors) from seven distinct sites of human proximal femur underwent DXA and muCT imaging and mechanical testing. The results revealed significant variations in BMC, morphometric indices and mechanical properties within the proximal femur. This work has demonstrated that the mechanical performance of each sub-region is highly dependent on the corresponding trabecular microstructure. BMD measured by DXA at standard regions of interest cannot resolve the variations in trabecular density and microstructure that govern the mechanical behavior of the proximal femur. This work suggests that a quantitative Singh index that uses high resolution QCT to monitor the trabecular microstructure at specific sub-regions of the proximal femur may allow better predictions of hip fracture risk in individual patients and an improved assessment of changing bone structure in response to pharmacological interventions.     

The effect of age on the distribution of 241Am in the rat body

In experiments with albino mongrel rats aged from 2 weeks to 1.5-2 years, the kinetics of 241Am distribution was studied after single intraperitoneal administration thereof. The content of 241Am in the skeleton was shown to decrease and in the liver to increase with age.     

Multigenerational exposure to uranium changes morphometric parameters and global DNA methylation in rat sperm

There is increasing evidence that environmental exposures early in fetal development influence phenotype and give rise to disease risk in the next generations. We previously found that lifelong exposure to uranium, an environmental contaminant, induced subtle testicular and hormonal defects; however, its impact on the reproductive system of multiple subsequent generations was unexplored. Herein, rats were exposed to a supra-environmental and non-nephrotoxic concentration of natural uranium (U, 40 mg·L⁻¹ of drinking water) from postnatal life to adulthood (F0), during fetal life (F1), and only as the germ cells from the F1 generation (F2). General parameters (reproductive indices, epididymal weight) and sperm morphology were assessed in the three generations. In order to identify the epigenetic effects of U, we analyzed also the global DNA methylation profile and described for the first time the mRNA expression levels of markers involved in the (de)methylation system in rat epididymal spermatozoa. Our results showed that the F1 generation had a reduced pregnancy rate. Despite the sperm number being unmodified, sperm morphology was affected in the F0, F1 and F2 generations. Morphometric analysis for ten parameters was detailed for each generation. No common parameter was detected between the three generations, but the head and the middle-piece were always modified in the abnormal sperms. In the F1 U-exposed generation, the total number of abnormal sperm was significantly higher than in the F0 and F2 generations, suggesting that fetal exposure to uranium was more deleterious. This effect could be associated with the pregnancy rate to produce the F2 generation. Interestingly, global DNA methylation analysis showed also hypomethylation in the sperm DNA of the last F2 generation. In conclusion, our study demonstrates that uranium can induce morphological sperm defects and changes in the DNA methylation level after multigenerational exposure. The epigenetic transgenerational inheritance of U-induced reproductive defects should be assessed in further experiments.     

The influence of age on the effectiveness of DTPA in reducing 141Ce retention in rats

The influence of age on the effectiveness of chelation treatment in reducing retention of radioactive cerium was studied in two- and six-week-old albino rats. 141Ce was administered intraperitoneally, followed immediately and after 24 and 48 hours by intraperitoneal administration of the tri-sodium calcium salt of diethylenetriaminepentaacetic acid--Na3(CaDTPA) at 380 mumol/kg body weight. The whole-body retention was determined 2, 4 and 6 days after radiocerium administration, when the animals were killed and the organ retention was determined. The chelation therapy significantly reduced the whole-body retention of radiocerium. This treatment was however twice as effective in older as in younger animals.     

The influence of fixatives and other variations in tissue processing on nuclear morphometric features

The influence on the area and numerical density of nuclei was investigated in 5-mm-thick slices of guinea pig liver for different fixatives and variations in tissue processing: delay in fixation, air drying, degree of acidity of 10% formalin (= 4% formaldehyde), Bouin and mercury-formalin fixatives, acetone and ethanol dehydration and understretching and overstretching of the paraffin-embedded sections. Air drying (either forced or as a result of delayed fixation), the type of fixative and the degree of acidity affected the nuclear area. Regarding the latter, nuclear area was approximately 25% lower for pH less than or equal to 3 as compared with pH greater than 5. In comparison with the standard tissue processing used, the nuclear density was higher after all of the variations studied (air drying, acetone dehydration and fixation). These findings indicate that nuclear area, in contrast to other tissue components, is relatively insensitive to variations in tissue processing. However, it is essential to regularly measure the pH of the fixative: deviations from pH = 7 should be carefully avoided in order to keep nuclear area variations as a result of tissue processing within acceptable limits.     

Volume of the conducting airways calculated from morphometric parameters

A method of calculating the volume of a tree distal to a cut at the origin of a branch, using branching, diameter and length ratios, has been developed. The method was applied to bronchial tree casts from human, dog, sheep, hamster, and rat lungs. It was found that the exponenta in the equation weight=k×diameter ^a is approximately equal to 3.0 in sheep lung casts, as found by Hooper (1977), but it is greater than 3.0 in casts from the other four species.     

The influence of model parameters on model validation

The study examined the sensitivity of two musculoskeletal models to the parameters describing each model. Two different models were examined: a phenomenological model of human jumping with parameters based on live subject data, and the second a model of the First Dorsal Interosseous with parameters based on cadaveric measurements. Both models were sensitive to the model parameters, with the use of mean group data not producing model outputs reflective of either the performance of any group member or the mean group performance. These results highlight the value of subject specific model parameters, and the problems associated with model validation.     

The effect of hydrological and morphometric parameters of temporary waterbodies on the structure and abundance dynamics of crustacean zooplankton

The effects of hydrological conditions and morphometry of the temporary waterbodies on the structure, abundance, and biomass of crustacean zooplankton are described. This study was performed in the southeast of the European part of Russia. The existence duration (hydrological regime) of the temporary waterbodies has the most profound effect on the zooplankton patterns. A significant effect was observed for the number of dominant species, the zooplankton biomass, the calanoid-cyclopoid ratio, and the Shannon index. The brackish lagoons were characterized by the highest biodiversity and abundance and the lowest values of these parameters were found in the steppe puddles and waterbodies of terraces above the flood-plain in the river valleys.