Slow growth rate of a deep-sea clam determined by 228Ra chronology.
The age of a deep-sea clam, Tindaria callistiformis, from 3803 m depth has been determined by 228Ra (6.7 year half-life) chronology of separated size fractions of a captured population. A length of 8.4 mm is attained in about 100 years. Shells of this size fraction show about 100 regularly spaced bands, indicating that the growth feature may be an annual one. (+info)
Radiographic features of bone in several strains of laboratory mice and of their tumours induced by bone-seeking radionuclides.
The natural radiographic appearance of the various bones of the skeleton are described for several strains of laboratory mice. The Harwell substrains of CBA, A and 101 are generally similar and become osteoporotic on ageing. Harwell C57BL have similar, but more delicately chiseled, bones. Harwell C3H mice have bones with stouter cortices and may show osteosclerosis on ageing. CF1 females (donated by Dr M. Finkel) showed osteosclerosis and osteophytic outgrowths when aged. NMRI mice (donated by Dr A. Luz) appeared larger than the pure-strain Harwell mice. In general, mouse bones are simple tubular structures with an ivory cortex and a marrow cavity. Cancellous trabecular bone is scanty, even in vertebrae, flat bones and the metaphyses of long bones. Bone-seeking radionuclides administered to mice lead to skeletal tumours: (a) osteosarcomata, which are commonly radio-opaque to a variable degree owing to calcified tumour bone, but which may be osteolytic, (b) primitive mesenchymal (angio-) sarcomata which are non-osteogenic and osteolytic, (c) fibrosarcomata--which also are osteolytic--and to local or general lymphomata from irradiation of parental cells in bone marrow, but no special radiological features have been found associated with these last-named tumours. (+info)
Cancer incidence after childhood nasopharyngeal radium irradiation: a follow-up study in Washington County, Maryland.
A population from a hearing clinic in Washington County, Maryland, in 1943-1960 was followed to assess the risk of developing neoplasms from radium treatment of the nasopharynx for adenoid hypertrophy. Of the 2,925 subjects who attended the clinic, 904 received radium treatment. A nonconcurrent prospective study compared the cancer incidence among the irradiated persons with that among persons with other treatments. Seven brain tumor cases (three malignant and four benign) were identified in the irradiated group versus none in the nonirradiated group (relative risk = 14.8, 95% confidence interval: 0.76, 286.3). A nonsignificant excess risk of thyroid cancer was detected in the irradiated group based on two cases in the exposed group and one case in the nonexposed group (relative risk = 4.2, 95% confidence interval: 0.38, 46.6). Decreased risks of breast cancer, female genital cancers, and prostate cancer were observed among the irradiated individuals, although these deficits were not statistically significant individually. The decreased risk of sex hormone-related cancers in the irradiated group suggests possible radiation damage to the pituitary, with consequent reduction in pituitary hormone output and alterations in sexual and other hormonal development in early life. This hypothesis needs further evaluation. (+info)
Portrait of Science. Scientist, technologist, proto-feminist, superstar.
Although Marie Curie is known primarily for her discovery of radium, her true gift to science was her realization that radioactivity is an intrinsic atomic property of matter rather than the result of chemical processes. She was one of the few Nobel laureates to win the prize twice (physics and chemistry). During her career and as one of the first prominent women scientists, she became increasingly aware of the need for funding for research and of the scientific freedom that money can bring. By nature shy and reserved, Marie's fame, as both a scientist and as an exemplar of a liberated professional woman of the roaring twenties, grew to superstar proportions. (+info)
Significant antitumor effect from bone-seeking, alpha-particle-emitting (223)Ra demonstrated in an experimental skeletal metastases model.
The therapeutic efficacy of the alpha-particle-emitting radionuclide (223)Ra (t(1/2) = 11.4 days) in the treatment against experimental skeletal metastases in rats was addressed. Biodistribution studies, involving measurement of (223)Ra in bone marrow samples, were performed in rats after i.v. injection. To study the therapeutic effect of (223)Ra, an experimental skeletal metastases model in nude rats was used. Animals that had received 10(6) MT-1 human breast cancer cells were treated with (223)Ra doses in the range of 6-30 kBq after 7 days. The biodistribution experiment demonstrated that (223)Ra was selectively concentrated in bone as compared with soft tissues. The femur content of (223)Ra was 800 +/- 56% of injected dose per gram tissue times gram body weight (b.w.; mean +/- SD) 1 day after the injection and 413 +/- 23% of injected dose per gram tissue times gram b.w. at 14 days. The femur:kidney ratio increased from (5.9 +/- 2.0).10(2) at 1 day to (7.2 +/- 3.0).10(2) at 14 days, whereas the femur:liver ratio increased from (6.2 +/- 0.2).10(2) to (9.1 +/- 6.6).10(2). Femur:spleen ratio increased from (8.1 +/- 0.3).10(2) at 1 day to (6.4 2.2).10(3) at 14 days. The femoral bone:marrow ratio was 6.5 +/- 2.1 after day 1 and larger than 15 at day 14. All of the tumor-bearing control animals had to be sacrificed because of tumor-induced paralysis 20-30 days after injection with tumor cells, whereas the rats treated with > or =10 kBq of (223)Ra had a significantly increased symptom-free survival (P < 0.05). Also 36% (5 of 14) of rats treated with 11 kBq and 40% (2 of 5) of rats treated with 10 kBq were alive beyond the 67-day follow-up period. No signs of bone marrow toxicity or b.w. loss were observed in the groups of treated animals. The significant antitumor effect of (223)Ra at doses that are tolerated by the bone marrow is most likely linked to the intense and highly localized radiation dose from alpha-particles at the bone surfaces. The results of this study indicate that (223)Ra should be additionally studied as a potential bone marrow-sparing treatment of cancers involving the skeleton. (+info)
Targeting of osseous sites with alpha-emitting 223Ra: comparison with the beta-emitter 89Sr in mice.
The bone-seeking property and the potential exposure of red marrow by the alpha-particle emitter (223)Ra (half-life, 11.43 d) were compared with those of the beta-emitter (89)Sr (half-life, 50.53 d). METHODS: The biodistributions of (223)Ra and (89)Sr were studied in mice. Tissue uptake was determined at 1 h, 6 h, 1 d, 3 d, and 14 d after intravenous administration. Radiation absorbed doses were calculated for soft tissues and for bone. Multicellular-level doses were estimated for bone marrow cavities. RESULTS: Both (89)Sr and (223)Ra selectively concentrated on bone surfaces relative to soft tissues. The measured bone uptake of (223)Ra was slightly higher than that of (89)Sr. At 24 h, the femur uptake of (223)Ra was 40.1% +/- 7.7% of the administered activity per gram of tissue. The uptake in spleen and most other soft tissues was higher for (223)Ra than for (89)Sr. Although predominant clearance of (223)Ra was observed from the soft tissues within the first 24 h, the bone uptake of (223)Ra, which was not significantly different from maximum after only 1 h, was not significantly reduced during the 14 d. Furthermore, little redistribution of (223)Ra daughter products away from bone was found (2% at 6 h and less than 1% at 3 d). Estimates of dose to marrow cavities showed that the (223)Ra alpha-emitter might have a marrow-sparing advantage compared with beta-emitters for targeting osteoid surfaces because the short-range alpha-particles irradiate a significantly lower fraction of the marrow volumes. At the same time, the bone surfaces will receive a therapeutically effective radiation dose. CONCLUSION: The results of this study indicate that (223)Ra is a promising candidate for high-linear-energy transfer alpha-particle irradiation of cancer cells on bone surfaces. (223)Ra can, together with its daughter radionuclides, deliver an intense and highly localized radiation dose to the bone surfaces with substantially less irradiation of healthy bone marrow compared with standard bone-seeking beta-emitters. (+info)
Beverages: bottled water. Direct final rule.
The Food and Drug Administration (FDA) is amending its bottled water quality standard regulations by establishing an allowable level for the contaminant uranium. As a consequence, bottled water manufacturers are required to monitor their finished bottled water products for uranium at least once each year under the current good manufacturing practice (CGMP) regulations for bottled water. Bottled water manufacturers are also required to monitor their source water for uranium as often as necessary, but at least once every 4 years unless they meet the criteria for the source water monitoring exemptions under the CGMP regulations. FDA will retain the existing allowable levels for combined radium-226/-228, gross alpha particle radioactivity, and beta particle and photon radioactivity. This direct final rule will ensure that the minimum quality of bottled water, as affected by uranium, combined radium-226/-228, gross alpha particle radioactivity, and beta particle and photon radioactivity, remains comparable with the quality of public drinking water that meets the Environmental Protection Agency's (EPA's) standards. FDA is issuing a direct final rule for this action because the agency expects that there will be no significant adverse comment on this rule. Elsewhere in this issue of the Federal Register, FDA is publishing a companion proposed, rule under the agency's usual procedure for notice-and-comment rulemaking, to provide a procedural framework to finalize the rule in the event the agency receives any significant adverse comments and withdraws this direct final rule. The companion proposed rule and direct final rule are substantively identical. (+info)
Rapid determination of 226Ra and uranium isotopes in solid samples by fusion with lithium metaborate and alpha spectrometry.
A simple and rapid method has been developed to determine 226Ra in rocks, soils, and sediments. Samples are decomposed by fusion with lithium metaborate and the melt is dissolved in a solution containing sulfates and citric acid. During the dissolution, a fine suspension of mixed barium and radium sulfates is formed. The microcrystals are collected on a membrane filter (pore size 0.1 microm) and analysed in an alpha spectrometer. Application of a 133Ba tracer enables us to assess the loss of the analyte, which only rarely exceeds 10%. All analytical operations, beginning from sample decomposition to source preparation for alpha spectrometry, can be accomplished within 1 or 2 h. With uranium determination, the filtrate is spiked with a 232U tracer and passed through a column loaded with a Dowex AG (1 x 4) anion-exchange resin in the sulfate form. Interfering elements are eluted with dilute sulfuric acid followed by concentrated hydrochloric acid. Uranium is eluted with water, electrodeposited on silver discs, and analysed in the alpha spectrometer. The method was tested on reference soil and sediment materials and was found to be accurate within the estimated uncertainties. (+info)