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PubMed2006

Thermodynamic stability of radioactivity standard solutions.

Optimal thermodynamic stability conditions must prevail when radioactivity standard solutions are prepared. These conditions are studied, they relate to: * The nature of the radioactive ion, which makes it possible to establish the pH of the solubilization medium at a given concentration, * The carrier concentration, which is determined by considering the radionuclide production method and the prior concentration in the original solution from the supplier, * The most stable oxidation state of the radioactive ion and of the carrier ion, which must be considered at the pH established by the solubilization medium. A procedure for all the glassware used in preparation has been implemented.

Drug Stability↗
PubMed2005

Production of radioactive particles for endovascular therapeutic interventions.

Recanalization is a common phenomenon that decreases the efficacy of embolization procedures. It can be inhibited by beta-radiation. Two novel ways of producing radioactive particles are described, by neutron beam irradiation of gold-containing microspheres, or by using the 32P binding capacity of zirconium-containing microspheres. Particles were tested in vivo, to assess their ability to deliver radioactivity locally, using canine renal artery, porcine rete mirabile, and rabbit ear embolization models. Both radioactive microspheres (198Au and 32P) showed no detectable activity outside the target territory. 32P microspheres demonstrated typical radiation changes in a porcine rete mirabile arteriovenous malformation model.

Animals↗
PubMed2004

Migration of implanted free radioactive seeds for adenocarcinoma of the prostate using a Mick applicator.

PURPOSE: This study investigates the rate of free seed migration and associated seed-related sequelae after using a radioimmunoguided Mick applicator technique to place radioactive seeds within the prostate. METHODS AND MATERIALS: Between December 1998 and September 2002, 120 patients diagnosed with prostate cancer underwent interstitial transperineal prostate brachytherapy with free (125)I or (103)Pd seeds positioned using a radioimmunoguided Mick applicator technique. Orthogonal pelvic and chest radiographs were obtained postimplant (Day 0) and at a second follow-up visit to determine the rate of radioactive seed embolization. RESULTS: On the day of implant (Day 0), 7 (6%) of the 120 men demonstrated single pulmonary seed emboli; none of these seeds migrated subsequently. During follow-up, 87 (72.5%) men had a total of 249 (2.0%) out of 12,524 seeds implanted migrate. Sixty-eight (0.55%) of the implanted seeds migrated to the lungs, an incidence common among brachytherapy techniques utilizing free or vicryl-laden radioactive seeds. No clinical symptoms or adverse sequelae from seed emboli have been reported. CONCLUSIONS: The rate of seed emboli to the pulmonary vessels or to other tissue localities resulting from a radioimmunoguided Mick applicator technique does not appear to be markedly different from the reported rate seen with other free seed techniques.

Adenocarcinoma↗
PubMed2006

The distribution pattern of radioactivity across different tissues in quantitative whole-body autoradiography (QWBA) studies.

This study explored whether common rules exist for the distribution patterns across tissues in tissue distribution studies. To investigate this we tested whether tissue:plasma partition coefficients (PCs) of radioactivity are correlated with muscle:plasma PCs. The relationships between PCs of radioactivity in muscle and those in other tissues were investigated in 25 tissues for 20 structurally unrelated drug candidates. Tissue distribution data were obtained by quantitative whole-body autoradiography. Linear regression analysis was performed for each tissue. Radioactivity from basic and acidic/neutral compounds was analyzed separately. Results for acidic/neutral compounds: for the majority of the tissues investigated, the tissue:plasma PCs were well correlated with muscle:plasma PCs (R2 > 0.7). Correlations were worse (R2 < 0.7) in blood, white fat, excretory organs and tissues protected by a penetration barrier (e.g. brain). Slope factors for the regression ranged from 0.2 (blood) to 3.8 (Harderian gland) and were correlated with neutral lipid contents in tissues. Results for basic compounds: in most tissues, slope factors appeared to be higher than for acidic/neutral compounds. Correlations, however, were poorer than for acidic/neutral compounds. Overall, the present study demonstrates that muscle:plasma PCs are indicative of the overall tissue distribution of drug-related material, as they are well correlated with tissue:plasma PCs in most other tissues. Correlations for acidic/neutral compounds differ from those for basic compounds. The found PC relationships provide an explanation for the distribution pattern across tissues usually seen in tissue distribution studies.

Animals↗
PubMed2006

Methylene blue dye versus combined dye-radioactive tracer technique for sentinel lymph node localisation in early breast cancer.

AIM: The study compared the accuracy and success rate of two techniques, methylene blue alone versus combined methylene blue and radioactive colloid in sentinel lymph node localisation in the management early breast cancer. METHODS: Three hundred and twenty-nine patients with tumours less than 2 cm on ultrasound assessment were prospectively evaluated. One hundred and seventy-three patients (Group A) underwent sentinel lymph node localisation using 1 ml of 1% methylene blue. A combined technique of both methylene blue and radioactive colloid was used in 156 patients (Group B). Application of both was subdermal and subareolar. Sentinel lymph nodes were examined by standard microscopy. Patients underwent breast conservation surgery or mastectomy and sentinel node guided four node axillary sampling+/-clearance. RESULTS: In Group A, the sentinel lymph node identification rate was 96.5%. The negative predictive value was 96.3%, with false negative of 3.7% and accuracy of 87.4%. In group B the identification rate for sentinel lymph node was 98.7%, with false negative of 4.1%, negative predictive value of 96%, and accuracy of 83.8%. CONCLUSION: Sentinel lymph node localisation using methylene blue or combined dye and radioactive tracer technique predicts the axillary lymph node status in early breast cancer with comparable success rates, accuracy and false negative rates. The combined technique facilitates quicker identification of sentinel lymph node; however the dye technique alone can be used successfully in centres without nuclear medicine facilities.

Axilla↗
PubMed2006

Natural radioactivity of granites used as building materials.

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of (238)U, (226)Ra, (232)Th and (40)K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1mSvy(-1) for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made.

Background Radiation↗
PubMed2006

Soil radioactivity and incidence of cancer in Nigeria.

The significance of exposure from natural radioactivity in soil and the potential risk for causing health detriment have not received adequate attention in Nigeria. Cancer has become a major cause of mortality in the recent times and now the public interest in the long-term effects of radiation on humans has assumed great prominence following the establishment of a nuclear regulatory body in Nigeria. This study is an effort to investigate a possible relationship between reported cancer incidence and external terrestrial radiation dose level across the six geo-political zones of the country. Data from the national cancer registries across the zones were compared with expected cancer incidences due to soil radioactivity based on the linear no-threshold model (LNT). A regression equation that best describe the reported cancer incidence and the expected cancer incidence was developed. It was observed that cancer cases attributable to radiation exposure due to soil radioactivity is low, constituting only between 1.3% and 9.2% of the total reported cases.

Background Radiation↗
PubMed2005

Comparative study of NK cell-mediated cytotoxicity using radioactive and flow cytometric cytotoxicity assays.

Cell-mediated cytotoxicity is a major effector pathway of the immune system. Thus far, radioactive assays have been widely used, but have significant disadvantages. Meanwhile, flow cytometric assays have been established but have not all been assessed simultaneously relative to the radioactive assays. Here, we have evaluated flow cytometric enumeration of surviving target cells, annexin-V binding and detection of activated caspase-3 and caspase-6 in direct comparison to the 51chromium (51Cr) release assay, and the JAM test. For assay evaluation NKL effector cells Fas-resistant K562 and Fas-sensitive Jurkat target cells were studied. Percent specific lysis measured for each E:T ratio was fitted to a sigmoid dose response curve. Both the flow cytometric and radioactive cytotoxicity assays showed equivalent background lysis (1-13%) but differed considerably with respect to maximum cytotoxicity (11-82% in K562 and 49-75% in Jurkat cells). Half maximum lysis ranged from 4:1 to 28:1 E:T ratios in K562 cells and from 1:3 to 24:1 in Jurkat cells, respectively. Flow cytometric enumeration of surviving target cells was the only assay which permitted detection of cytotoxicity at considerable lower E:T ratios (in K562 cells 1:4 to 2:1 and in Jurkat cells 1:4 to 1:1) than the conventional assays. Prolonged incubation over 24 h did not improve the sensitivity for flow cytometric enumeration of surviving target cells or the JAM test. The observed differences in the lysis of target cells are likely to reflect different sensitivity of cell death-associated changes which are measured by each assay. Thus, the particular choice of a cytotoxicity assay must be carefully adapted to the experimental situation under study.

Caspase 3↗
PubMed1990

Stable [57Co]-bleomycin complex with a very high specific radioactivity for use at very low concentrations.

A method for the preparation of 57Co-labelled bleomycin (BLM) possessing very high specific radioactivity and suitable for use at the nanomolar concentration range is described, and validated using a biological assay. Chelation of BLM with Co(II) results in a very stable complex. However, association does not occur below the micromolar concentration range. A nanomolar [57Co]BLM solution with maximal specific radioactivity can be easily prepared, without handling unreasonable amounts of radioactivity, provided that: equimolar solutions of BLM and [57Co]Cl2 are first mixed at the micromolar concentration range and that the mixture is then diluted a thousand times to reach the nanomolar concentration range.

Animals↗
PubMed2001

Separation of radioactive metabolites in cultured tea cells fed with [14C]phenylalanine using high-speed counter-current chromatography.

Separation of radioactive metabolites in cultured tea cells fed with [14C]phenylalanine was conducted using high-speed counter-current chromatography. Among seven components obtained our studies focused two metabolites, i.e. (-)-epicatechin and D,L-catechin. The specific radioactivity of (-)-epicatechin was 212.01 KBq/mg, amounting to 8.5% of the total radioactivity of ethyl acetate extract while that of D,L-catechin was 1.0006 MBq/mg or 5.4% of the total.

Carbon Radioisotopes↗
PubMed1991

Radical prostatectomy and adjuvant radioactive gold seed placement: results of treatment at 5 and 10 years for clinical stages A2, B1 and B2 cancer of the prostate.

Between 1977 and 1988, 131 patients with adenocarcinoma of the prostate underwent combined radical prostatectomy and intraoperative radioactive gold seed placement. Of these 131 patients 80 were clinically assessed as having stage A2 (12), B1 (43) or B2 (25) cancer and they are the subject of this review. The average dose of radioactivity administered to each patient was 96.6 mCi, and mean followup was 65 months (median 64 months). No patient in this series received any other form of adjuvant therapy until disease recurrence was demonstrated. Local recurrences were observed in 2 patients (2.5%) in this series while distant recurrences were observed in 10 (12.5%). Cancer specific survival free of disease at 5 years was 100% for clinical stage A2, 91% for B1 and 75% for B2 cancers. The 10-year survival free of disease was 100% for clinical stage A2, 82% for B1 and 68% for B2 cancers. Covariants of clinical stage and seminal vesicle involvement influenced survival free of disease in a statistically significant manner (p less than 0.05) while pathological stage and degree of tumor differentiation did not. Mild to severe complications were observed in 12 patients (15%). Intraoperative placement of radioactive gold seeds into unresected pelvic tissues surrounding the site of prostatectomy offers a theoretical advantage in treatment by delivering tumoricidal levels of irradiation to residual foci of cancer not appreciated at the time of surgery. Our results suggest that increases in cancer specific survival free of disease over that previously reported for prostatectomy alone may be achieved through this combined treatment regimen. Furthermore, it is our opinion that therapeutic gains can be achieved without the attendant increases in morbidity and treatment delay often associated with adjuvant external beam radiotherapy.

Adenocarcinoma↗
PubMed1985

Radical prostatectomy with adjuvant radioactive gold for prostatic cancer: a preliminary report.

A total of 71 patients with prostatic carcinoma underwent radical prostatectomy combined with instillation of radioactive gold seeds between January 1, 1977 and July 1, 1982. Gold seeds were implanted intraoperatively into the region of the prostatic vascular pedicles and surrounding fibrolymphatic tissue after removal of the prostate and seminal vesicles. Of the patients with disease confined to the prostate clinically 46.7 per cent had microscopic extraprostatic local tumor extension. We believe that patients with extraprostatic local tumor derive therapeutic benefit from the addition of adjuvant radioactive gold seeds at prostatectomy. Because of the inaccuracy of clinical staging by rectal examination, we have elected to use radioactive gold seeds in all of our patients at prostatectomy. To date, local recurrence has been noted in 5.6 per cent of our patients and systemic progression in 14.1 per cent.

Adenocarcinoma↗
PubMed1986

Place of radioactive iodine in treatment of thyrotoxicosis.

The effect of treatment of thyrotoxicosis with drugs, radioactive iodine, or surgery in different age groups is reviewed. In Graves' disease and toxic multinodular goitre the remission rate is about 40-50% after antithyroid drugs, but these drugs have little effect in toxic adenoma. Hypothyroidism developed in 35-49% of patients who had had thyroidectomy, and the risks of operation are high. The risk of malignant disease and genetic abnormalities was not significantly greater after treatment with radioactive iodine in any age group. In general, treatment with radioactive iodine should have priority over thyroidectomy at all ages.

Abnormalities, Drug-Induced↗
PubMed2001

Dose-volume histograms based on serial intravascular ultrasound: a calculation model for radioactive stents.

BACKGROUND AND PURPOSE: Radioactive stents are under investigation for reduction of coronary restenosis. However, the actual dose delivered to specific parts of the coronary artery wall based on the individual vessel anatomy has not been determined so far. Dose-volume histograms (DVHs) permit an estimation of the actual dose absorbed by the target volume. We present a method to calculate DVHs based on intravascular ultrasound (IVUS) measurements to determine the dose distribution within the vessel wall. MATERIALS AND METHODS: Ten patients were studied by intravascular ultrasound after radioactive stenting (BX Stent, P-32, 15-mm length) to obtain tomographic cross-sections of the treated segments. We developed a computer algorithm using the actual dose distribution of the stent to calculate differential and cumulative DVHs. The minimal target dose, the mean target dose, the minimal doses delivered to 10 and 90% of the adventitia (DV10, DV90), and the percentage of volume receiving a reference dose at 0.5 mm from the stent surface cumulated over 28 days were derived from the DVH plots. Results were expressed as mean+/-SD. RESULTS: The mean activity of the stents was 438+/-140 kBq at implantation. The mean reference dose was 111+/-35 Gy, whereas the calculated mean target dose within the adventitia along the stent was 68+/-20 Gy. On average, DV90 and DV10 were 33+/-9 Gy and 117+/-41 Gy, respectively. Expanding the target volume to include 2.5-mm-long segments at the proximal and distal ends of the stent, the calculated mean target dose decreased to 55+/-17 Gy, and DV 90 and DV 10 were 6.4+/-2.4 Gy and 107+/-36 Gy, respectively. CONCLUSIONS: The assessment of DVHs seems in principle to be a valuable tool for both prospective and retrospective analysis of dose-distribution of radioactive stents. It may provide the basis to adapt treatment planning in coronary brachytherapy to the common standards of radiotherapy.

Aged↗
PubMed2000

A simple method for non-radioactive PCR-SSCP using MDE gel solution and a midi gel format: application for the detection of variants in the GLUT1 and CTLA-4 genes.

The need to identify disease-causing mutations and DNA polymorphisms has increased with the continuing identification of new candidate genes. PCR single-strand conformation polymorphism (PCR-SSCP) is one of the techniques most widely used to identify a mutant sequence or a polymorphism in a known gene. However, the original SSCP protocols using the incorporation of radioactive label and polyacrylamide gel electrophoresis on sequencing gels for detection were labour intensive and time-consuming. Here we describe a simple SSCP protocol using MDE gel solution and a midi gel format to detect SSCP variations in the glucose transporter gene GLUT1, that we have previously analysed with the standard radioactive SSCP protocol, and we have also tested this method on the previously described point mutation (A/G transition in exon 1) of the CTLA-4 (cytotoxic T lymphocyte associated-4) gene. All known variants were detected. Based on the results, this technique appears to be simple, with no use of radioactive labels and with easy handling of the gel. Furthermore, it needs little optimisation, is relatively rapid and highly sensitive. We propose this method for the first screening for candidate gene variants.

Abatacept↗
PubMed2002

Natural radioactive nuclides in some Tunisian thermo-mineral springs.

Radioactivity in some Tunisian thermo-mineral springs (11 hot mineral springs and one cold spring) has been determined for the first time in Tunisia using radiochemical separation procedures. The obtained results show that 238U activity concentrations vary between 1.5 and about 43 mBq/l. The measured activities of 234U and 226Ra range from 1.1 to about 82.2 mBq/l and 34-3,900 mBq/l. respectively. The radioactive disequilibria in these waters are in excess of concentration of 234U compared to that of 238U. The 226Ra/234U activity ratios are high and in the range of 9.0-691.0). U, Th and Ra activities are similar to those published for other non-polluted regions of the world. Radioactivity in the only cold mineral water from Aïn Oktor is very low, and thus health hazards due to the consumption of this water are not expected.

Environmental Monitoring↗
PubMed1999

Radioactive contamination: state of the science and its application to predictive models.

Information on environmental levels and transport processes of natural and anthropogenic radioactivity, although plentiful, is widely scattered, and relatively few attempts have been made to summarize and synthesize this information. Furthermore, most experimental observations and experiments on environmental radioactivity have been designed for documentation or testing of specific hypotheses, rather than for providing key information for transport simulation models or on fundamental processes which such models seek to represent. This paper examines three basic questions, namely (1) what is the current state of the science of radioecology?; (2) how well is this science being incorporated into predictive models?; and (3) how well are the models being used to guide and improve the science? These discussions will be preceded by a brief description of the field of radioecology, and comments on its relevance to other sciences as well as to major societal problems stemming from environmental releases of radioactivity. In addition to assessing the current state of the science and its use in predictive models, specific ideas for improving both the science and its associated models will be advanced. These ideas fall under the categories of (1) environmental transport processes and model parameters, (2) estimating exposure and dose to human and ecological receptors, and (3) dose-effect relationships for plants and animals.

Journal Article↗
PubMed2003

Radioactivity in cervical mucus after intraperitoneal deposition of Tc-99m labelled albumin particles before and after sterilisation.

OBJECTIVE: To study the transport of radiolabelled albumin particles from the pouch of Douglas to cervical mucus. STUDY DESIGN: A prospective randomised study, including 10 healthy women, undergoing laparoscopic sterilization. A solution of human serum albumin particles, labelled with Technetium 99(m) (Tc-99(m)) was injected into the pouch of Douglas, either before or after sterilisation. RESULTS: Gamma camera images showed gradual spread to the entire peritoneal cavity. Blood samples, showed increasing levels of radioactivity. Measurement of radioactivity in cervical mucus showed significant activity both in women sterilized before and after the deposition. CONCLUSION: The study showed evidence of transport of radioactivity from the pouch of Douglas to cervical mucus. The transport seemed to consist of free activity since no radionuclide labelled particles could be detected in cervical mucus. The transport was probably haematogenous or lymphatic and not intraluminal through the fallopian tube. Further studies utilizing particles comparable in size to fertilized ova are required to design methods for evaluating the transport from the fallopian tube to the uterine cavity.

Adult↗