Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RADIOACTIVITY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,351 records · Page 75Linked to original sources
PubMed1991

Determination of the ultraviolet absorbance and radioactivity of purine compounds separated by high-performance liquid chromatography. Application to metabolic flux rate analysis.

A double detection system for the determination of adenine metabolism in biological tissues using isocratic ion-pair reversed-phase chromatography is presented. Two isocratic ion-pair separations were used: (i) 10 mM NH4H2PO4, 2 mM tetrabutylammonium phosphate (PIC reagent A) and 18% acetonitrile for the determination of nucleotides and (ii) 50 mM KH2PO4, 1 mM PIC reagent A and 1% acetonitrile for the determination of monophosphorylated nucleotides, nucleosides and nucleobases. The parallel detection of ultraviolet absorbance at 254 nm and the radioactivity of separated purine compounds allows the detection of pool sizes and of the specific radioactivities in tracer kinetic experiments. The high-performance liquid chromatography methods were applied to the determination of flux rates during adenine nucleotide metabolism in suspensions of Ehrlich mouse ascites tumour cells. The pathways of adenine metabolism in cells during the proliferation and plateau phases of tumour growth were compared.

Animals↗
PubMed1991

Failure of open radioactive 125iodine implantation to control localized prostate cancer: a study of 41 patients.

We studied 41 patients with localized prostate cancer who underwent bilateral pelvic lymphadenectomy with open insertion of radioactive 125iodine. Followup was a minimum of 5 years. Of the patients 13 died: 10 of recurrent prostatic adenocarcinoma (including 4 of 5 with pathological stage D1 cancer) and 3 of unrelated causes within 2 years of implantation without clinical evidence of prostate cancer. Of the 28 remaining patients 16 have known recurrence of cancer (positive bone scan and increasing prostate specific antigen (PSA) level or positive tissue biopsy]. Six patients have strong suspicion of local recurrence with elevated PSA levels (greater than 4.0 in 5) and increasing induration on digital rectal examination. Only 6 of the 41 patients (14.6%) are without evidence of disease. Openly implanted radioactive 125iodine does not appear to control effectively adenocarcinoma of the prostate.

Aged↗
PubMed1981

Transcatheter embolization of advanced renal cell carcinoma with radioactive seeds.

Advanced renal cell carcinoma was treated by transcatheter embolization with radioactive seeds. There were 14 patients with nonresectable or metastatic disease (stage IV) and 8 with stage II tumors treated. In 8 patients the tumor was implanted with radon seeds, complemented by 2,500 rad of external beam therapy, and 10 were treated by embolization with 125iodine seeds. The total dose delivered ranged form 1,600 to 14,000 rad. Several patients also had intra-arterial chemotherapy. Survival was improved over previously reported studies: 13 of 22 (59 per cent) at risk for 2 years and 5 of 15 (33 per cent) for 5 years. Distant metastases did not resolve but significant local palliation was achieved. Tumor size decreased in all patients, 8 of whom subsequently underwent nephrectomy. Other local effects included pain control (10 per cent), weight gain (75 per cent) and control of hemorrhage (88 per cent). Toxicity was minimal and consisted of mild nausea or pain. This approach, using a low energy emitter, allows selective high dose radiation of the tumor, while sparing the adjacent normal tissues. In contrast to renal artery occlusion with inert embolic material, subsequent nephrectomy in patients with disseminated disease is not necessary. Transcatheter embolization with radioactive seeds should be considered a reasonable palliative procedure in patients with nonresectable primary renal cell carcinoma.

Adenocarcinoma↗
PubMed2000

Elemental and radioactive analysis of commercially available seaweed.

Edible seaweed products have been used in many countries, specifically Japan, as a food item. Recently these products have become popular in the food industry because of a number of interesting medicinal properties that have been associated with certain edible marine algae. Very little control exists over the composition of these products, which could be contaminated with a number of agents including heavy metals and certain radioactive isotopes. Fifteen seaweed samples (six local samples from the coast of British Columbia, seven from Japan, one from Norway and one undisclosed) were obtained. All samples were analyzed for multiple elements, using ICP mass spectrometry and for radioactive constituents. It was found that six of eight imported seaweed products had concentrations of mercury orders of magnitude higher than the local products. Lead was found at somewhat higher concentrations in only one local product. Laminaria japonica had the highest level of iodine content followed by Laminaria setchellii from local sources. Only traces of cesium-137 were found in a product from Norway and radium-226 was found in a product from Japan. Arsenic levels were found to be elevated. In order to estimate the effect of these levels on health, one needs to address the bioavailability and the speciation of arsenic in these samples.

British Columbia↗
PubMed2006

Non-radioactive analysis of lipid-linked oligosaccharide compositions by fluorophore-assisted carbohydrate electrophoresis.

Lipid-linked oligosaccharides (LLOs) are the donors of glycans that modify newly synthesized proteins in the endoplasmic reticulum (ER) of eukaryotes, resulting in formation of N-linked glycoproteins. The vast majority of LLO analyses have relied on metabolic labeling with radioactive sugar precursors, but these approaches have technical limitations resulting in many important questions about LLO synthesis being left unanswered. Here we describe the application of a facile non-radioactive technique, fluorophore-assisted carbohydrate electrophoresis (FACE), which circumvents these limitations. With FACE, steady-state LLO compositions can be determined quantitatively from cell cultures and animal tissues. We also present FACE methods for analysis of phosphosugars and nucleotide sugars, which are metabolic precursors of LLOs.

Animals↗
PubMed1985

A non-radioactive DNA probe to identify Shigella and enteroinvasive Escherichia coli in stools of children with diarrhoea.

A non-radioactive biotinylated DNA probe was constructed to detect Shigella and enteroinvasive Escherichia coli (EIEC). Specimens were examined with the biotinylated probe after removing streptavidin-binding glycoproteins with proteinase K. Both biotinylated and radioactive probes detected 125 pg of target-cell DNA after hybridisation for 24 h and exposure to indicator dyes or X-ray film for 4 h. Both probes hybridised with 52 EIEC and none of 16 non-EIEC examined; they also hybridised with stool blots from 11 of 13 children with culture-proven shigellosis or EIEC diarrhoea and were negative with stool blots from 43 children who were culture negative for Shigella and EIEC. Biotinylated DNA probes can be as sensitive as radiolabelled probes, but have the advantage of a longer shelf-life and greater availability.

Biotin↗
PubMed1981

Influence of dietary molybdenum on the metabolism of intravenously injected radioactive copper in the rat.

Control and molybdenum-supplemented rats (Mo rats) were injected i.v. with 64Cu or 67Cu. The distribution of radioactivity over plasma, liver, and kidney, as well as the intracellular distribution in these organs, was studied as a function of time. Compared with control rats, the level of radioactive Cu in the plasma of Mo rats was increased. The results for liver and kidney of Mo rats had to be corrected for a decrease in specific activity of 64Cu; they suggested that the 64Cu release from the liver and the 64Cu uptake in the kidney of Mo rats ran parallel to that in control rats for up to 8 hr; after which, an increase in both organs of the Mo-rats followed. 64Cu in the subcellular particles and in a high molecular weight (MW) protein of the cytoplasma of the organs of Mo rats was increased compared with control rats. In control rats the transport of 64Cu from a 10,000 MW protein to a 30,000 MW protein of the cytoplasma of the kidney seemed to be much slower compared with that of the liver, but Mo had no influence on this process in either liver or kidney.

Animals↗
PubMed1992

Measurement of lymphocyte proliferation: critical analysis of radioactive and photometric methods.

Different methods of lymphocyte proliferation are compared to identify a non-radioactive alternative to 3H-thymidine-test. The enzymatic assays evaluating the turnover of mitochondrial dehydrogenases (MTT-test) and lysosomal hexosaminidase (NAG-test) proved not sensitive enough to substitute for 3H-thymidine incorporation. The incorporation of the nucleotide analog 5-bromodeoxyuridine (BrdU) can be exploited using an ELISA-system (enzyme linked immunosorbent assay) employing a monoclonal anti-BrdU antibody to measure cell proliferation. An optimized test protocol of the BrdU-ELISA which fulfills the requirements for a sensitive and practicable non-radioactive alternative to 3H-thymidine-test is presented.

Autoradiography↗
PubMed2001

Radiological impacts of natural radioactivity in Abu-Tartor phosphate deposits, Egypt.

Phosphate and environmental samples were collected from Abu Tartor phosphate mine and the surrounding region. The activity concentration of 226Ra (238U) series, 232Th series and 40K were measured using a gamma-ray spectrometer. The activities of uranium isotopes (238U, 235U and 234U) and 210Pb were measured using an alpha spectrometer and a low-background proportional gas counting system, respectively, after radiochemical separation. The results are discussed and compared with the levels in phosphate rocks from different countries. It seems that the Abu Tartor phosphate deposit has the lowest radioactivity level of exploited phosphate of sedimentary origin. 226Ra/238U, 210Pb/226Ra, 234U/238U and 226Ra/228Ra activity ratios were calculated and are discussed. The radioactivity levels in the surrounding region and the calculated exposure dose (nGy/h) will be considered as a pre-operational baseline to estimate the possible radiological impacts due to mining, processing and future phosphate industrial activities. To minimize these impacts, the processing wastes should be recycled to the greatest possible extent.

Apatites↗
PubMed1999

Development of a non-radioactive endpoint in a modified local lymph node assay.

A murine local lymph node assay (LLNA) has been developed as an alternative to guinea pig models for contact sensitization testing. Although the LLNA appears to be a little less sensitive than the most stringent of guinea pig assays, it provides a rapid, objective, quantitative and cost-effective method for screening strong contact sensitizers and has advantages with respect to animal welfare. However, a potential disadvantage is the need for the use of radioactive material. We have reported previously that an ex vivo assay based on similar principles to the original in vivo LLNA, but using a non-radioactive endopoint, was valid for the prediction of strong sensitizers. This ex vivo assay was not sensitive enough to allow prediction of moderately potent ones. In this study, we propose a new parameter, Corrected IL-2 Index (CII), for the prediction of moderate sensitizers. To obtain CII the IL-2 release in the supernatant of the cell culture is corrected for lymph node weight ratio and ratio of CD4-positive subset. We found that CII predicted the allergenicity of moderate sensitizers, including the ones recommended by the OECD in guideline 406, such as mercaptobenzothiazole and hexyl cinnamic aldehyde. The allergenicity of metal salts, such as potassium dichromate, ammonium tetrachloroplatinate and cobalt chloride, was also predicted by the CII. We conclude that the use of CII as an index significantly increases the sensitivity of the ex vivo method so that moderate sensitizers may also be detected.

Allergens↗
PubMed2003

Allergenicity evaluation of p-chloro-m-cresol and p-chloro-m-xylenol by non-radioactive murine local lymph-node assay and multiple-dose guinea pig maximization test.

p-Chloro-m-cresol (PCMC) and p-chloro-m-xylenol (PCMX) are known to cause allergic contact dermatitis. For risk assessment of skin sensitizers, information on dose-response profiles in the induction and elicitation phases and cross-reactivity with analogous chemicals are important. In the non-radioactive local lymph-node assay (LLNA) using 5-bromo-2'-deoxyuridine instead of 3H-methyl thymidine, significant effect on lymph node cell proliferation was detected at 10% PCMC and 25% PCMX, while in the multiple-dose guinea pig maximization test (GPMT) at least one animal tested in the group was sensitized at a 5 ppm induction dose of either chemical. When mean skin reaction score in an animal group maximally sensitized with each allergen with the GPMT was plotted against log challenge concentration, linear regression lines with high correlations were obtained in both cases. The calculated elicitation threshold was lower for PCMC than PCMX. The area under the linear regression line between the threshold point and 1% of the elicitation concentration, another index of relative elicitation potency, was also greater for PCMC. Bidirectional cross-reactivity between PCMX and PCMC was detected in the GPMT. PCMC was thus identified in both LLNA and GPMT as a stronger sensitizer than PCMX in both the induction and elicitation phases. These results suggest that the non-radioactive LLNA is a simple and useful method for evaluating allergenicity in the induction phase, while the GPMT using a maximally sensitized animal group is more suitable for assessing the dose-response profile and cross-reactivity in the elicitation phase.

Allergens↗
PubMed1976

[Enzymatic preparation of peptides of the general type: L-Ala-D-Glu-L-mesodiaminopimelyl (L)-D (140) Ala by transfer reactions between non radioactive corresponding peptides and D-alanine (140)].

Membrane bound LD-transpeptidase of Streptococcus faecalis ATCC 9790 was used to catalyse transpeptidation reactions between non radioactive peptide donors of the general type: L-Ala-D-Glu (L)meso-A2pm(L)-D-Ala and D-(14C) alanine acceptor. The presence of one or two amide residues on the carboxyl groups of glutamic acid and meso-diaminopimelic acid increases the transfer reactions and subsequently the yield in radioactive peptides L-Ala-D-Glu (L)meso-A2pm(L)-D-(14C) Ala.

Acyltransferases↗
PubMed1991

Localization of elastase and tumor necrosis factor alpha mRNA by non-radioactive in situ hybridization in cultures of alveolar macrophages.

Digoxigenin is a new tool for labeling probes which can be detected with the help of specific antibodies in the cell by indirect or direct immunostaining. In contrast to the biotin-reaction, the advantage of digoxigenin is that it does not appear in animal or human cells in nature. In comparison to radioactive labeling methods it is favorable in terms of short exposure time and precise localization of signals in the cell. In this paper we describe the localization of elastase and tumor necrosis factor alpha (TNF alpha) mRNA by non-radioactive in situ hybridization of rat alveolar macrophages in cell culture after stimulation with welder steam dusts. Using digoxigenin labeled probes the determination of specific mRNA's expression and their precise localization in the cytoplasm of the cell could be achieved within one day.

Animals↗
PubMed1997

Radioactive technetium-99m labelling of Salmonella abortusovis for the assessment of bacterial dissemination in sheep by in vivo imaging.

We report the development and validation of a 99mTc-labelling technique of bacteria, applied to Salmonella abortusovis. The radioactive labelling is obtained using a pre-tinning step of the cells followed by direct incubation of S. abortusovis suspension with 99mTc-pertechnetate. Several procedures with different amounts of stannous tin (SnF2 or SnCl2) were evaluated. The selected method, respectful of bacterial viability, provided a 30% labelling yield. Viability of 99mTc-labelled bacteria was assessed by flow cytometry using rhodamine 123 and was demonstrated to be unchanged, turbidimetric measurements showing only a slight increase in the growth rate for radiolabelled cells. Incubation of 99mTc-labelled S. abortusovis with pronase, saponine and urea demonstrated labelling stability and suggested an intra-cellular localization for 99mTc. A preliminary study was also conducted in sheep to evaluate the value of the imaging of radiolabelled S. abortusovis. Spatial and temporal patterns of their in vivo dissemination in the lymphatic system after a sub-cutaneous injection were compared with control lymphoscintigraphic agents. These imaging data supported the assumption that the radioactivity detected in vivo was proportional to the number of 99mTc-labelled bacteria.

Animals↗
PubMed1989

Determination of 75Se-labelled selenite and metabolites in plasma and urine by high-performance liquid chromatography with on-line radioactivity detection.

A reversed-phase ion-pair high-performance liquid chromatographic method with on-line radioactivity detection for the simultaneous determination of 75Se-labelled selenite and metabolites has been developed. With this system a good resolution of various radiolabelled selenium complexes can be achieved. The detection limit of the radioactivity detector (signal-to-noise ratio = 3) is 49 pg of selenium (specific activity of 3 GBq/mg selenium) per millilitre of urine or plasma ultrafiltrate. The detector response is independent of both the chemical structure of the selenium complexes and the matrix composition of the samples. This method may serve as a reference system for other high-performance liquid chromatographic systems with less specific and sensitive detectors.

Animals↗
PubMed1989

Determination of cisplatin and related platinum complexes in plasma ultrafiltrate and urine by high-performance liquid chromatography with on-line radioactivity detection.

A reversed-phase ion-pair chromatographic method with on-line radioactivity detection for the simultaneous determination of 195mPt-labelled cisplatin and related platinum complexes has been developed. With this system a good resolution of various radiolabelled platinum complexes can be achieved. The detection limit of the radioactivity detector is 10 ng of cisplatin (specific activity of 15 MBq/mg cisplatin) per millilitre of urine or plasma ultrafiltrate. The detector response is independent of both the chemical structure of the platinum complexes and the matrix composition of the samples. This method may serve as a reference system for other high-performance liquid chromatographic systems with less specific and sensitive detectors.

Animals↗
PubMed1997

A modified HPLC method for monensin analysis in liposomes and nanocapsules and its comparison with spectrophotometric and radioactive methods.

Monensin is a carboxylic ionophore which can potentiate the immunotoxin activity against human tumors in vitro and in vivo. Currently monensin is being encapsulated in liposomes and nanocapsules in our laboratory. The reported methods for monensin analysis by spectrophotometric and HPLC lack the required sensitivity. We have developed a sensitive HPLC method for analysis on monensin. Separation was achieved on a Beckman C18 reverse phase column with methanol-acetonitrile-methylene chloride-water-acetic acid (45:20:25:9.5: 0.5) as the mobile phase. The eluent was reacted with vanillin reagent in the post column reactor at 70 degrees C. The reagent reacted with monensin and formed a pink color, which was detected at 520 nm. The retention time of monensin was found to be 6 min. By using this method it was possible to quantify monensin down to 100 ng ml-1, with a signal to noise ration of > 17:1. Linearity was observed within the range of 10 to 100 ng (r2 > 0.99). Inter-day standard deviations for monensin samples of 20, 50 and 80 ng were 0.675, 0.543 and 0.736 respectively. Alternative methods of analysis include using radioactive [3H]monensin in liposomes which can be quantified by scintillation counter. The results from the HPLC, spectrophotometric and radioactive method were compared and were found to be within acceptable limits. The HPLC method is being utilized in our laboratory for quantitative analysis of monensin in liposomes and nanocapsules.

Capsules↗
PubMedDate not supplied

Sensitive non-radioactive nucleic acid hybridization assay for plum pox virus detection.

A new non-radioactive sandwich hybridization assay was designed to simplify the analysis of a large number of plant samples. Plant material was homogenized in 0.5% SDS and added directly to the hybridization reaction, in which a pair of identifying probes were used. One of the probes was biotinylated capture RNA specific for plum pox virus (PPV) strain SK-68; the other RNA probe was synthesized from a plasmid bearing the adjacent sequence of this strain and was labelled with digoxigenin (DIG). Both purified viral RNA and crude extracts from PPV-infected plants were used as target for sandwich hybridization. The hybridization reaction was carried out in a streptavidin-coated ELISA plate. After extensive washing, the viral RNA was detected by conventional colour reaction using anti-DIG/alkaline phosphatase conjugate. In comparative experiments, we have shown that this non-radioactive detection system is more sensitive than conventional ELISA techniques and we were able to detect virus-specific RNA in more than 50% of the ELISA-negative samples.

Enzyme-Linked Immunosorbent Assay↗