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PubMed1994

Restriction mapping of phage lambda vectors using non-radioactive methods.

In order to take advantage of non-radioactive methods, we have developed two plasmids (p lambda LE and p lambda RE) for mapping restriction sites of long inserts cloned in phage lambda vectors. These plasmids are constructed by cloning the left 402-bp and right 560-bp phage lambda genome ends, respectively. To map restriction sites, the cloned sequences in p lambda LE and p lambda RE are labeled with digoxygenin and hybridized to partially digested lambda DNA. The ladder of bands detected with these probes can be used to construct restriction maps in the same way as those obtained using radioactively labeled cos complementary oligodeoxyribonucleotides [Rackwitz et al., Gene 30 (1984) 195-200].

Bacteriophage lambda↗
PubMed1990

Non-enzymatic covalent binding of radioactivity from [14C]thiourea to rat lung protein.

In vitro covalent binding of radioactivity from [14C]thiourea (TU) to rat lung protein occurs in the presence of 100% CO2. Prior boiling of lung slices results in a subsequent increase in covalent binding. Covalently bound radioactivity was released from rat lung homogenates and acid-insoluble protein obtained from animals treated with [14C]TU. The release was achieved with ammonium ion. One possibility suggested by these results is that the bound species may involve binding of isothiocyanic acid via a thiocarbamylation reaction.

Acetates↗
PubMed1989

Isocratic high-performance liquid chromatographic determination of the concentration and specific radioactivity of phosphoenolpyruvate and uridine diphosphate glucose in tissue extracts.

A rapid and efficient isocratic high-performance liquid chromatographic method for studying the metabolism of phosphoenolpyruvate and uridine diphosphate glucose (UDPG) has been developed. For each compound this method can measure tissue concentrations in the range 0.1-1000 nmol/g of tissue and determine specific radioactivity. All measurements can be performed in 200 mg of tissue. The recoveries of uridine diphosphate [6-3H]glucose and phosphoenol[1-14C]pyruvate from liver tissue homogenates were 97 and 99%, respectively. Following intra-arterial infusion of [6-3H]glucose and [U-14C]lactate in conscious rat, the concentration and specific radioactivity of phosphoenolpyruvate and UDPG were determined in rat liver. The method may be applied to experimentation in small animals using radiolabelled precursors in order to quantitate in vivo the glycogenic and gluconeogenic fluxes.

Animals↗
PubMed1995

Determination of 25-hydroxyvitamin D3 in human plasma using a non-radioactive tetranorvitamin D analogue as an internal standard.

A convenient non-radioactive method for assaying plasma 25-hydroxyvitamin D3 is described. The method uses 22-hydroxytetranorvitamin D3 as an internal standard and includes two-step liquid- and solid-phase extractions and quantification by normal-phase HPLC. The intra- and inter-assay coefficients of variation were 2.2% and 2.4%, respectively, and the analytical recovery of 25-hydroxyvitamin D3 added to plasma was quantitative. Assay linearity was obtained in the range 0.5-4.0 ml of plasma. When compared with the method employing a radioactive 25-hydroxyvitamin D3 tracer, the correlation coefficient was 0.990 (slope 0.999 and intercept 1.19 ng/ml).

Adult↗
PubMedDate not supplied

Environmental radioactivity measurement intercomparisons in the UK.

The results of two recent (1989 and 1990) nationwide radioactivity-measurement intercomparisons covering a range of pure beta- and beta/gamma-emitting radionuclides are presented. Over fifty laboratories took part in the first exercise and, in general, the results were satisfactory although most laboratories confined themselves to gamma-ray measurements only. There were some areas of concern, notably decay-scheme data, statements of uncertainty and cascade-summing effects. A follow-up meeting was held to discuss these points with the participants. As a result of this meeting, a second exercise was held, covering a different range of nuclides at lower-activity levels and seeking to discover how participants had improved their procedures in the light of the results from the first exercise. The overall results of the two exercises are reviewed in the light of i) UK radioactivity-monitoring arrangements and ii) the National Measurement Accreditation Scheme (NAMAS).

Environmental Pollutants↗
PubMed1990

Use of non-radioactive DNA probes for detection of Campylobacter jejuni and Campylobacter coli in stool specimens.

DNA probes specific for C. jejuni (pDT1720 containing a 1475 base pair fragment) and for C. jejuni and C. coli (pDT1719 containing a 1845 base pair fragment) were isolated from a bacteriophage lambda gt11 genomic library of C. jejuni, using antiserum prepared against a 46 kDa major outer membrane protein of C. jejuni. The two probe-fragments had different restriction maps and were only moderately related by DNA hybridization analysis. A non-radioactive labelling kit which consisted of alkaline phosphatase conjugated anti-digoxigenin antiserum and 5-bromo-4-chloro-3-indoyl phosphate with nitroblue tetrazolium as the colour substrate, which gives a purple colour for positive hybridization, was used to test 140 stool specimens, 70 of which were culture positive and 70 of which wer culture negative for Campylobacter spp. The pDT1720 fragment (C. jejuni probe) could detect a minimum of 1 x 10(5) C. jejuni cells on filters, whereas the pDT1719 fragment (C. coli probe) was 100-fold less sensitive. The C. jejuni probe demonstrated a sensitivity of 93% with culture positive stool samples, however, 15% of culture negative samples were also recorded as positive using this non-radioactive DNA probe.

Blotting, Southern↗
PubMed1992

Sensitive non-radioactive detection of HIV-1: use of nested primers for the amplification of HIV DNA.

This report describes the use of the polymerase chain reaction (PCR) for the non-radioactive detection of HIV-1 proviral genomic sequences in HIV-1 infected cells. We have developed a sensitive assay, using three different sets of nested primers and our results show that this method is superior to standard PCR for the detection of HIV-1 DNA. The assay described features the use of a simple and inexpensive sample preparation technique and a non-radioactive hybridization procedure for confirmation of results. To test the suitability of the assay for clinical purposes, we tested cell samples from 76 anti-HIV-1 positive patients. All were positive for at least one primer set: 88% were positive for all three sets of primers; 9% were positive for two sets of primers and 3% were positive for only one set of primers. It provides a useful approach to the study of HIV-1 infection in patient samples where genomic copies often are present at such low numbers that they are otherwise undetectable.

Base Sequence↗
PubMedDate not supplied

Computer applications to radioactive-seed: brain-tumor implants.

Malignant brain tumors, in general, and anaplastic astrocytoma and glioblastoma multiforme in particular, have been highly refractory to conventional treatments including surgery, chemotherapy and external-beam irradiation. Although better local control can be achieved with high-dose, external beam irradiation, necrosis of normal brain tissue reduces the quality of life and survival. In order to localize the radiation dose given to brain tumors, the temporary implantation of 125I and 192Ir seeds is undergoing clinical trials at several medical centers. Computers play a key role in this treatment modality: in addition to being essential for image reconstruction of CT scans, a computer is used to reconstruct a tumor volume from outlined regions on individual cuts; a programable calculator is used in conjunction with a stereotaxic head holder to obtain the coordinates of the radioactive seeds; a radiation-therapy, treatment-planning computer is used to optimize the radioactive-seed positions and strengths, and to generate the corresponding dose distribution.

Astrocytoma↗
PubMed1995

Repeating the avidin "chase" markedly improved the biodistribution of radiolabelled biotinylated antibodies and promoted the excretion of additional background radioactivity.

Immunoscintigraphy using radiolabelled biotinylated monoclonal antibodies followed by infusion of avidin as a "chase" has been recently reported to improve the biodistribution for both immunoscintigraphy and radioimmunotherapy. In this study the circulating protein-bound and avidin-binding fractions of radiolabelled biotinylated antibodies were determined serially after injection of an avidin "chase", and the effect of repeating the avidin chase was also studied. Nude mice bearing KT005 human osteogenic sarcoma were injected with radiolabelled biotinylated antitumour monoclonal antibody (OST7). After injection of an avidin chase, the protein-bound and avidin-binding fractions in plasma were determined serially using the trichloroacetate method and avidin-Sepharose gel. The biodistribution of radiolabelled biotinylated OST7 was compared after single and double avidin chases with no chase. At 6 h after the first avidin chase in mice injected with radioiodinated and technetium-labelled biotinylated OST7, 67.7% and 67.8%, respectively, of the plasma radioactivity was available for binding to avidin and was cleared from the circulation. Reinjection of avidin decreased the plasma radioactivity and improved the biodistribution of the radiolabelled biotinylated antibodies. Repeating the avidin chase markedly improved the biodistribution of the radioiodine-labelled biotinylated antibody when compared with the use of a single avidin chase. This new method for radioimmunotherapy is sure to protect the critical organs from radiation injury without decreasing the therapeutic effect.

Animals↗
PubMed1992

Effect of wheat bran on excretion of radioactively labeled estradiol-17 beta and estrone-glucuronide injected intravenously in male rats.

Urinary and fecal estrogen excretion were studied in male rats fed a non-fiber wheat starch diet (dietary fiber less than 1%; NF group; n = 4), a low-fiber wheat flour diet (dietary fiber 2%; LF group; n = 4) or a high-fiber wheat bran diet (dietary fiber 11.6%; HF group; n = 3). Short-term effects of the experimental diet on estrogen excretion were studied after i.v. injection of 5 microCi (0.185 MBq) of [14C]estradiol-17 beta (E2) into the tail vein of the rats fed the diets for 2 days. After 3 weeks on the experimental diets, the long-term effects were studied after injection of 5 microCi of [14C]E2 and 10 microCi of [3H]estrone-3-glucuronide (E1-gluc). The diet was found to affect estrogen excretion. The short-term effect indicated that rats fed the HF diet excreted a relatively large amount of labeled compounds in the feces during the first day after injection, while rats fed the NF or the LF diets excreted about half that amount over the same period. On the other hand, urinary excretion of labeled compounds was significantly higher in the NF and LF rats. The long-term effect resulted in steeper slopes (P less than 0.05) of the fecal excretion profiles of rats fed the HF diet as compared with rats fed the NF and LF diets, indicating an accelerated fecal excretion of labeled compounds in the HF rats. The kinetic profiles of 14C and 3H radioactivity in blood plasma indicated a fast decrease (t1/2 of less than 2 min) for both [14C]E2 and [3H]E1-gluc. It was concluded that, owing to the short-term effect of wheat bran intake, during the first 24 h after i.v. administration relatively large amounts of radioactively labeled compounds are excreted in feces of rats fed the HF diet. In contrast, excretion is lower in urine of these rats. When the microflora is adapted to the experimental diet the wheat bran diet still results in an accelerated fecal excretion of labeled compounds, which might be attributed to an interruption of the enterohepatic circulation of estrogens. This might result in lowered plasma and/or tissue estrogen levels and hence a decreased exposure of estrogen-sensitive tissue to estrogens, which might decrease risk on mammary (breast) cancer development.

Animals↗
PubMed1994

Labelling of proteins with 11C in high specific radioactivity: [11C]albumin and [11C]transferrin.

A method for the 11C-labelling of proteins for use in positron emission tomography is presented. Human iron-free transferrin and human serum albumin were treated with [11C]cyanogen bromide of high specific radioactivity under physiological conditions to give the labelled proteins in high radiochemical yields using a simple and rapid procedure. In a typical experiment, 2.0 GBq of [11C]albumin was obtained in 28-32 min synthesis time counted from the end of bombardment. The radiochemical purity was in all cases > 98% and the specific radioactivity varied with the amount of protein between 10.7-141 GBq mumol-1 (0.3-3.8 Ci mumol-1). The radiochemical yield of labelled product as a function of pH and protein concentration was studied. The labelled products were characterized using both high performance liquid chromatography and high performance capillary electrophoresis with u.v.-and radiodetection in series.

Carbon Dioxide↗
PubMedDate not supplied

Absolute radioactivity measurements by the use of a 4pibeta-4pigamma detector configuration.

The radioactivity of 60Co and 134Cs sources were measured using a 4pibeta-4pigamma detector configuration with a well-type NaI(Tl) crystal and a sandwich type 4pibeta detector composed of two sheets of NE102A plastic scintillator coupled to a slender photomultiplier tube. The beta-detector was inserted into the well of the gamma-detector. Since counting efficiencies in both the beta- and gamma-channels can be kept high, excellent counting statistics were attainable even when weak sources were measured. This configuration can also be used for radioactivity measurements based upon the direct integral counting of 4pibeta + 4pigamma logic sum signals, and two independent results can be obtained for every measurement. This technique is especially useful for the standardization of complex decaying nuclides.

Beta Particles↗
PubMed2005

Biokinetics of inhaled radioactive methane in rats: a pilot study.

Current dosimetric models for radioactive methane assume 1% of inhaled methane is absorbed, all 3H activity is converted immediately to [3H]H2O, and 14C activity is converted immediately to [14C]CO2 (50%) and organically bound carbon (50%). Results of a pilot study using rats to test these models suggest the models overestimate uptake but underestimate organic fixation of 3H and 14C, especially in liver. Also, the biokinetic properties of organically bound 3H and 14C in liver were markedly different from other tissues. Preliminary dose estimates based on observed uptake and organic fixation of label suggest current methane models likely overestimate radiation doses from radioactive methane by 3- to 10-fold.

Animals↗
PubMed2005

Radioactive byproducts in [18O]H2O used to produce 18F for [18F]FDG synthesis.

Potential radioactive byproducts in [(18)O]H(2)O irradiated with 9.6 MeV protons to produce (18)F were analyzed theoretically and experimentally. Twenty two nuclear reaction cross sections included in the National Nuclear Data Center's (NNDC) data base were selected from the possible nuclear reactions between 9.6 MeV protons and a silver havar target. Ten radionuclides: (52)Mn, (55)Fe, (55)Co, (56)Co, (57)Co, (58)Co, (59)Ni, (95)Tc, (96)Tc and (109)Cd were detected experimentally in [(18)O]H(2)O by using high purity germanium semiconductor detectors. The activities of the 10 radionuclides were distributed between 4B q and 1.2k Bq. These activities were less than the reference values given in the International Basic Safety Standards. The radionuclides derived from nuclear reactions between a silver target body and 9.6 MeV protons at a beam current 25 microA for 60 min irradiation would be exempt from restrictions for radioactive waste. The purified [(18)F]FDG prepared from (18)F produced by irradiating a silver havlar target with 9.6 MeV protons was not contaminated by the radionuclides.

Drug Contamination↗
PubMed2006

International guidance on the establishment of quality assurance programmes for radioactivity measurement in nuclear medicine.

A new guidance document for the implementation of quality assurance (QA) programmes for nuclear medicine radioactivity measurement, produced by the International Atomic Energy Agency, is described. The proposed programme is based on the principles of ISO 17025 and will enable laboratories, particularly in developing countries, to provide consistent, safe and effective radioactivity measurement services to the nuclear medicine community.

Guidelines as Topic↗
PubMed2006

HPGe virtual point detector for radioactive disk sources.

Validity of the model of a virtual point detector (implying existence of a point where all interactions virtually occur) was confirmed for measurements of radioactive disk sources with HPGe detectors. The existing correlation of the count rates with the distance between the virtual plain detector and the detector face makes it possible to inter- and extrapolate calibration curves for disk radioactive sources for use at different source-detector face distances. The dependence of the distance between the virtual plane detector and the detector face on the photon energy was studied for sources of various radii.

Journal Article↗
PubMed2006

Planar chromatographic analysis and quantification of short-lived radioactive metabolites from microdialysis fractions.

A sensitive radiochromatographic method for the quantitative determination of compounds labelled with short-lived beta-emitting radionuclides in microdialysates is described. The method is well suited for microdialysis (MD) samples, which have small volumes and low concentrations of compounds. An 18F-labelled (beta+; T(1/2)=109.8 min) radiopharmaceutical, (1R,2S)-4-[18F]fluorometaraminol (FMR), was injected intravenously into rats, and microdialysis fractions were then collected from the blood at 15 min intervals. Fractions were analyzed for FMR and its radioactive metabolites by planar chromatography combined with digital photostimulated luminescence autoradiography. The lowest detectable 18F-radioactivity was 0.24 Bq/application and the limit of quantification was 0.31 Bq/application with 4-16 h exposure. The method was found to be highly sensitive and linear in the range of 0.1 Bq-2 kBq. This method thus allows the quantification of beta-emitting radiopharmaceuticals in sequential microdialysis fractions with good time-resolution.

Animals↗
PubMed2005

Enhanced efficiency in cell killing at the penetration depths around the Bragg peak of a radioactive 9C-ion beam.

PURPOSE: To evaluate the potential importance of radioactive 9C-ion beam in cancer radiotherapy. METHODS AND MATERIALS: Human salivary gland (HSG) cells were exposed to a double-radiation-source 9C beam at different depths around the Bragg peak. Cell survival fraction was determined by standard clonogenic assay. For comparison, the same experiment was conducted for a therapeutic 12C beam. To determine relative biologic effectiveness (RBE) values, HSG cells were also irradiated with 60Co gamma-rays of fractionation scheme as the reference. RESULTS: The 9C beam was more efficient in cell killing at the depths around its Bragg peak than was the 12C beam, which corresponded to the 9C-ion stopping region and where delayed low-energy particles were emitted. The RBE value at 50% survival level for the 9C beam varied from 1.38 to 4.23. Compared with the 12C beam, the RBE values for the 9C beam were always higher; an increase in RBE by a factor of up to 1.87 has been observed at the depths distal to the Bragg peak. CONCLUSION: The potential advantage of radioactive 9C-ion beam in cancer therapy has been revealed at low dose rate in comparison with a therapeutic 12C beam. This observation, however, remains to be investigated at therapeutic dose rates in the future.

Carbon↗