Nuclear data for reactor production of 131Ba and 133Ba.

The newest radioisotope for brachytherapy treatment of prostate cancer is 131Cs (t1/2 = 9.69 d, 100% EC). Generated via electron capture decay of 131Ba (t1/2 = 11.6 d, 100% EC), 131Cs has been used in brachytherapy for prostate cancer since 2004. The 131Ba parent is produced through neutron capture of enriched 130Ba in a nuclear reactor. For large-scale production of 131Ba, an accurate knowledge of production and burnup cross sections of 131Ba are essential. In this paper, we report two group cross sections (thermal and resonance integrals) for 130Ba and 131Ba and a new measure of the half-life of 131Ba. Targets consisting of milligram quantities of enriched 130Ba (∼35%) were irradiated in Oak Ridge National Laboratory's High Flux Isotope Reactor at thermal and resonance neutron fluxes of (1.9-2.1) × 1015 and (5.8-7.0) × 1013 neutrons·cm-2 s-1, respectively, for durations ranging from 3 to 26 days. In addition, cadmium covered samples of 130Ba were irradiated for 1 hour at 12.6% full reactor power (10.7 MW). The yield of 131Ba approaches a saturation value of ∼60 GBq (∼1.6 Ci) per mg of 130Ba for 20 days irradiation at a thermal neutron flux of 1.8 × 1015 n·s-1·cm-2, with a thermal/epithermal ratio of ∼30. Under the above experimental conditions, the two group cross sections of 130Ba are 6.9 ±â€¯0.5 b (thermal, σ0) and 173 ±â€¯7 b (resonance, I0). These values represent the sum of cross sections to metastable and ground states of 131Ba. For 131Ba, the empirically measured thermal cross section is 200 ±â€¯50 b assuming an I0/σ0 of 10. This cross section is reported for the first time. Further, the half-life of 131Ba was remeasured to be 11.657 ±â€¯0.008 d. Lastly, this study also resulted in the co-production of 133Ba (t1/2 = 10.52 y, 100% EC). The experimental yield of 133Ba is ∼370 MBq (∼10 mCi) per mg of 132Ba (thin target) for one cycle irradiation in the High Flux Isotope Reactor, and measured two-group 132Ba cross sections are 7.2 ±â€¯0.2 b and 39.9 ±â€¯1.3 b. These values also represent the sum of cross sections to metastable and ground states of 133Ba.

[(76) Br]BMK-152, a nonpeptide analogue, with high affinity and low nonspecific binding for the corticotropin-releasing factor type 1 receptor.

Corticotropin-releasing factor (CRF), a neuropeptide, regulates endocrine and autonomic responses to stress through G-protein coupled receptors, CRF(1) or CRF(2) . A PET ligand able to monitor changes in CRF(1) receptor occupancy in vivo would aid in understanding the pathophysiology of stress-related diseases as well as in the clinical development of nonpeptide antagonists with therapeutic value. We have radiolabeled the CRF(1) receptor ligand, [8-(4-bromo-2,6-dimethoxyphenyl)-2,7-dimethylpyrazolo[1,5-α][1,3,5]triazin-4-yl]-N,N-bis-(2-methoxyethyl)amine (BMK-152) (ClogP = 2.6), at both the 3 and 4 position with [(76) Br]. Using in vitro autoradiography saturation studies the 4-[(76) Br]BMK-152 exhibited high affinity binding to both rat (K(d) = 0.23 ± 0.07 nM; n = 3) and monkey frontal cortex (K(d) = 0.31 ± 0.08 nM; n = 3) consistent with CRF(1) receptor regional distribution whereas with the 3-[(76) Br]BMK-152, the K(d) s could not be determined due to high nonspecific binding. In vitro autoradiography competition studies using [(125) I]Tyr(0) -o-CRF confirmed that 3-Br-BMK-152 (K(i) = 24.4 ± 4.9 nM; n = 3) had lower affinity (70-fold) than 4-Br-BMK-152 (K(i) = 0.35 ± 0.07 nM; n = 3) in monkey frontal cortex and similiar studies using [(125) I]Sauvagine confirmed CRF(1) receptor selectivity. In vivo studies with P-glycoprotein (PGP) knockout mice (KO) and their wild-type littermates (WT) showed that the brain uptake of 3-[(76) Br]BMK/4-[(76) Br]BMK was increased less than twofold in KO versus WT indicating that 3-[(76) Br]BMK-152/4-[(76) Br]BMK was not a Pgp substrate. Rat brain uptakes of 4-[(76) Br] BMK-152 from ex vivo autoradiography studies showed regional localization consistent with known published CRF(1) receptor distribution and potential as a PET ligand for in vivo imaging of CRF(1) receptors.

Influence of rainfall characteristics on elimination of aerosols of cesium, strontium, barium and tellurium deposited on grassland.

This work is aimed at quantifying foliar transfer of cesium, strontium, barium and tellurium under the influence of rainfall characteristics (intensity, frequency and time elapsed between contamination and first rainfall). Grassland boxes were contaminated by dry deposition of multi-element aerosols of (137)Cs, (85)Sr, (133)Ba and (123m)Te. They were grown in a greenhouse under controlled conditions. The treatments consisted of mowing and applying rainfalls (8 and 30 mmh(-1)) at different times after the contamination. At a leaf area index of 5.9+/-1.9, interception of the aerosols was similar for the 4 radionuclides (83.8+/-5.9%). Dew produced significant radionuclide accumulation in the base of the vegetation and transfer to the soil. For moderate intensity, an early (2 days after contamination) first rainfall was as efficient, in terms of leaf wash-off, as a longer rainfall occurring later (6 days after contamination). For early rainfalls, eliminated activities were comparable because the influence of rain intensity was compensated by rain duration. However, for late rainfalls, wash-off efficiency increased with rainfall intensity. Total transfer factors (TTF) were determined on whole grass immediately after 4 rainfalls and at harvest. After 4 medium intensity rainfalls, rain frequency did not influence total transfer factors (TTF) of strontium, barium and tellurium (about 0.2, 0.3 and 0.35 Bq kg(fresh weight)(-1) by Bq m(-2), respectively). Cesium TTF value was lower in the case of a weekly rain (0.1 against 0.2 Bq kg(fresh weight)(-1) by Bqm(-2)). TTF values were similar for twice-a-week rainfalls, whatever their intensity. They were higher for weekly rains of high intensity (between 0.3 and 0.75 Bq kg(fresh weight)(-1) by Bqm(-2) against 0.1-0.35 Bq kg(fresh weight)(-1) by Bq m(-2), depending on the radionuclides). TTF values attested that wash-off was more efficient when rainfalls lasted longer. Field loss on the top of the leaves was well described by an offset exponential model. The half-lives varied with rainfall characteristics from 4 days for cesium, strontium and barium to 20 days for tellurium. The offset value varied between 0% for tellurium (high intensity rainfalls) and 14% for cesium (medium intensity rainfalls).

[A case of an uncommon foreign body in the esophagus]. / Niespotykane cialo obce przelyku.

Esophagial foreign bodies are mostly located in the sites of the physiological and pathological narrowings. A case of 58 year old patient with profound mental impairment, who swallowed a stone of 3 cm in diameter and a molar tooth has been presented. The treatment and prognosis was complicated by retention of barium contrast in the lungs. The patient underwent the bronchoscopy and double esophagoscopy. Foreign body was successfully removed through external approach (oesophagotomy).

Long-term retention of injected barium-133 in man.

Data are presented on the whole-body retention of 133Ba (half-life 10.74 y), over periods of up to 13 y after injection into six healthy male volunteers aged 25-81, and on their levels of biochemical markers for bone turnover. The results are relevant to propositions underlying the ICRP's current (Publication 67) and former (Publication 20) models of alkaline earth metabolism. The tracer was predominantly skeletal within weeks of the injection, as predicted in the current model. The mean retention accorded satisfactorily throughout with predictions based on the current model, but this accord does not necessarily validate the model, for two reasons. First, parameter values attributed to barium were influenced by data emerging during the early years of this study. Second, bone resorption rates in these subjects, as indicated by urinary markers, appear insufficient to explain the long-term reductions in skeletal retention which, in the present model, arise exclusively through this mechanism.

Prolonged intraocular pressure reduction following intravitreal barium injection in rabbits.

The isolated ciliary epithelium contains barium-inhibitable potassium channels. The present study was aimed at testing the in vivo effects of barium on aqueous humor dynamics in rabbits. BaCl2 was administered to one eye by topical delivery or intravitreal injection. Dynamic measurements included intraocular pressure, outflow facility, episcleral venous pressure and aqueous flow (fluorophotometry). Barium dynamics were studied using 133Ba. Intraocular pressure was not altered after topical administration of BaCl2. 133Ba was not detected in the aqueous after delivery of eyedrops containing the radiochemical. Intraocular pressure decreased following intravitreal injection of BaCl2 (0.15 microgram). The onset of this pressure reduction was 12 to 16 hr, the maximum decrease (-11.3 mmHg) occurred at 2 days, and the effect persisted (-4.2 mmHg) for approximately 12 days after the injection. Outflow facility and episcleral venous pressure were not altered. However, aqueous humor flow 5 to 6 days after the injection was decreased by 42% to 63% as determined by fluorophotometry or calculated tonographic data. The injection was not associated with findings of intraocular inflammation. Radioactivity was detected in the vitreous within the first 3 days after the injection; however, activity was present in the ciliary body, equally distributed between the cell membrane and soluble fractions, seven days after the injection. Intravitreally injected BaCl2 results in a prolonged intraocular pressure decrease relating to reduced aqueous formation. While the mechanism(s) for the BaCl2-induced decrease in pressure are not clear, possibilities include a Ba2+ interaction with ciliary epithelial K+ or N-type Ca2+ channels.

Metabolism of injected barium in six healthy men.

Data are presented on the early metabolism and long-term retention of 133Ba (half-life 10.74 y) injected into six healthy male volunteers at ages 25-81 y. The tracer appeared to be mainly skeletal within several days, much earlier than predicted by the ICRP's model of alkaline earth metabolism. Excretion was mainly fecal, the relative fecal:urinary clearance up to 14 d ranging from 6 to 15 in the six subjects. The whole-body retention at 50 d (mean 8%, range 4.5 to 12%) was similar to that inferred from published data on the retention of injected Ra in man (mean 7%, range 3-13%). For about 1 y thereafter, the retention of Ba could be represented by simple power functions of time, with the rate of loss correlating with the excretory plasma clearance rate inferred over the first 4 d. In the subject aged 81 y, the pattern differed from that established following an earlier injection at age 60, but the differences were not necessarily related to advancing age.