PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “COBALT, RADIOACTIVE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed1998

Cobalt-57 as a SPET tracer in the visualization of ischaemic brain damage in patients with middle cerebral artery stroke.

In PET studies we have shown the usefulness of cobalt radionuclides for the visualization and quantification of ischaemic damage in stroke. In the present study, we explored 57Co2+ as a SPET tracer. Uptake of radioactivity was estimated by using a cobalt enhancement ratio defined as the ratio of cobalt uptake in the affected region versus a similar volume in the non-affected contralateral side. Clinical status was assessed with the Orgogozo stroke score at the time of scanning and at least 60 days after admission. Nineteen patients (11 men, 8 women) with a middle cerebral artery stroke were examined with 57Co2+ SPET 0-30 days after stroke onset. Our investigations show enhanced cobalt uptake in the infarcted brain tissue in patients with a major stroke and little clinical improvement. There was a significant correlation between the cobalt enhancement ratio and the Orgogozo score at the time of scanning and discharge. Our results suggest that 57Co2+ SPET is suitable for determining the extent of (possibly calcium-mediated) damage in stroke and in the assessment of potential therapeutic interventions.

Adult↗
PubMed1994

PC-10 immunostaining of proliferating cell nuclear antigen in posterior uveal melanoma. Enucleation versus enucleation postirradiation groups.

PURPOSE: It is difficult to assess the viability of uveal melanoma after radiotherapy treatment. The purpose of the current study is to investigate PC-10 monoclonal antibody of proliferating cell nuclear antigen as a possible marker for cell proliferation and tumor viability in conventionally processed histologic preparations of uveal melanoma irradiated by brachytherapy as well as in nonirradiated melanomas. METHODS: Thirteen enucleated eyes with posterior uveal melanoma that were treated by brachytherapy (cobalt 60 or ruthenium 106 radioactive plaques) were included in this study. Thirteen enucleated eyes of the same size with nonirradiated posterior uveal melanoma served as controls. The tumors were stained with PC-10 monoclonal antibody to proliferating cell nuclear antigen. All clinical and histologic data of the tumors were recorded and analyzed. RESULTS: Five of the irradiated tumors showed positive staining with PC-10, although with a low score. Four of these tumors showed regrowth, and the fifth tumor was treated with a low-irradiation dose (5500 rad). In the nonirradiated tumor group, nine were positive for PC-10 staining, with a higher score. Significant correlation was found in this group between the PC-10 score and the mitotic figure count, but not with other prognostic factors. In three of four tumors that caused metastatic death, the PC-10 staining was positive and had a high score. CONCLUSIONS: PC-10 immunostaining is a simple, reproducible method that can be applicable to conventionally processed histologic preparations. It clearly shows that cellular proliferation activity in nonirradiated and irradiated uveal melanomas. Based on the small number of cases reported herein, it seems that the PC-10 score can correlate with prognosis, but further studies should be performed.

Adult↗
PubMed1989

Episcleral plaque radiotherapy for uveal melanoma.

The use of radioactive Iodine, Ruthenium, Iridium and Cobalt plaques of varying dimensions to treat choroidal and ciliochoroidal melanomas is discussed and placed in perspective with other treatment modalities. The regression pattern following plaque treatment appears to be more rapid for tumours that are more poorly differentiated. The visual results following plaque brachytherapy compare very favourably with those following local resection and external beam radiation. Ocular complications are significantly greater for tumours whose initial thickness exceeds 8 mm. The survival rater after plaque treatment is compared with that for patients who have had primary enucleation for equivalent-sized tumours.

Brachytherapy↗
PubMed1998

Electrodeposition of radioactive rhenium onto stents to prevent restenosis.

Radioactive stents are currently being evaluated for preventing restenosis. A major difficulty to overcome is the need to load any pre-manufactured stents with defined amounts of radioactivity at the time of use. Using stents that are preloaded by the manufacturer is not ideal because the stent length usually differs from the length needed for a specific lesion and the amounts of radioactivity varies widely due to ongoing decay of the source. Thus, we have developed a novel method that allows any currently used stainless steel or tantalum stent to be coated with radioactive rhenium. The method involves placing the stent in a series of rinsing and electroplating solutions, one containing radioactive rhenium (186Re, 188Re, or both). The overall processing time is 15 min and the procedure may be conveniently applied just prior to the stent insertion. The plated stent contains radioactive rhenium in a 1.2 microm-thick cobalt layer, with an outer 2 microm layer of gold. The gold layer gives the radioactive stent excellent radiochemical stability, good bending and biocompatibility properties, and improves stent visibility during fluoroscopy.

Angioplasty, Balloon, Coronary↗
PubMed1976

The effect of cobalt on the uptake of plasma iron by the liver.

1. After an intraperitoneal injection of 59Fe the recovery of radioactivity in the liver, but not in other tissues, was increased in cobalt-pretreated rats. There was no proportional increase in the radioactivity recovered from liver haem. 2. Rats were injected intravenously with serum containing protein-bound 59Fe and 125I-labelled albumin as a marker. At various times after injection the specific radioactivities of iron in plasma and of non-haem iron in liver were determined; corrections were applied for the content of plasma in samples of liver. In cobalt-pretreated rats there was a more rapid loss of 59Fe radioactivity from the plasma and a corresponding increase in the uptake of 59Fe into liver non-haem iron. 3. The results are discussed in relation to the possible sites of action of cobalt, and the possibility is considered that only a fraction of the liver non-haem iron may be involved.

Animals↗
PubMed1987

Measurements of induced radioactivity in electron- and photon-irradiated beef.

Samples of beef were irradiated with electrons of approx. 10- and 13.5-MeV energies or with 60Co gamma-ray photons (1.17 and 1.33 MeV). Induced radioactivity was measured with a gamma-ray spectrometer, consisting of a Ge(Li) detector and a multichannel analyzer. No induced radioactivity could be detected in the photon-irradiated samples; also for 10-MeV electrons the activity was below the detection limit. The irradiation by 13.5-MeV electrons, however, resulted in measurable radioactivity and the amount of 13N-activity was in agreement with previously calculated values. These measurements confirm previous conclusions that irradiation of food with electrons at 10 MeV or even at 13.5 MeV does not constitute any health risk due to radioactivity. Part of the induced radioactivity from 13.5-MeV electron irradiation is due to neutron capture, and the results suggest that several neutron sources contribute to the measured radioactivity.

Animals↗
PubMed1982

[The concentrations of 60Co and stable cobalt in the migratory marine organism (author's transl)].

In order to investigate both the contamination level and distribution of radioactive nuclides in the marine environment, the concentrations of both 60Co and stable cobalt were determined. The samples collected from the sea around Japan were fishes, squids. The analytical method for 60Co was consisted of the radiochemical separation using ion exchange resins followed with the low background beta counting, and that for stable cobalt was the spectrophotometric determination. The results obtained were as follows: (1) The viscera of squids was found to enrich both 60Co and stable cobalt. (2) No 60Co was detected in fishes except the liver of bonito taken from the north west Pacific. (3) The correlation between 60Co and stable cobalt was rather good in the squids samples. (4) The enrichment factors for squids and fishes agreed well with the values reported by B. Patel or S.E. Tompson.

Animals↗
PubMed1976

Carcinoma of the prostate. Its treatment by a combination of radioactive gold-grain implant and external irradiation.

Out of 67 patients treated with radiotherapy from 1967 to August 1972, a small group of 17 patients were treated by a combination of radioactive gold grain implant plus external Cobalt-60 teletherapy. The average dose from the implant was 4000 rads, which was supplemented with external irradiation to a total dose of 8000 rads TD. Because of the small number of patients and the short follow-up, no definite conclusions can be drawn at this time. The technique used permits the delivery of a higher total tumor dose of about 8000 rads with relatively low complication rate.

Gold Radioisotopes↗
PubMed2000

X-ray attenuation coefficients of high-atomic-number, hexanuclear transition metal cluster compounds: a new paradigm for radiographic contrast agents.

RATIONALE AND OBJECTIVES: The purpose of this study was to examine the radiologic attenuation properties of the parent cluster compounds, particularly attenuation as a function of discrete photon energy, before investigating ligand substitutions, which are necessary to improve cluster biocompatibility and to impart desirable physicochemical properties. MATERIALS AND METHODS: The linear attenuation coefficients for solutions of the cluster compounds Ta6Br14, K8Ta6O19, and (H3O)2W6Cl14 were determined at 60, 80, 103, 122, and 140 keV from gamma-ray transmission measurements with americium-241, xenon-133, gadolinium-153, cobalt-57, and technetium-99m radioactive sources. Transmission measurements were obtained for a fixed time interval that ensured a statistically accurate count distribution exceeding 20,000 counts through the sample for each trial. RESULTS: On a strictly mole per liter basis, a 0.075 mol/L aqueous solution of K8Ta6O19 showed 1.08 times the attenuation of 0.063 mol/L aqueous iohexol at 60 keV and 3.30 times the attenuation at 80 keV. Similarly, a 0.05 mol/L methanolic solution of (H3O)2W6Cl4 showed 0.96 times (96%) the attenuation of 0.063 mol/L aqueous iohexol at 60 keV but 3.09 times the attenuation of the iohexol solution at 80 keV. Attenuations of 0.063 mol/L aqueous iohexol and 0.0125 mol/L Ta6Br14 (ie, at approximately one-fifth the iohexol concentration) were comparable at greater than 60 keV. CONCLUSION: These results confirm the theoretic potential for use of early transition metal cluster compounds as radiographic contrast agents. At higher x-ray energies, cluster compounds demonstrate multiplied x-ray attenuation relative to iodinated contrast agents.

Contrast Media↗