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PubMed2004

Development of an automated electroplater and dosimetry system for the electrodeposition and quality control of radioactive stents.

An automated electrodeposition system for the preparation of radioactive stents and an automated dosimetry system based on the Optidos beta-scintillation detector for the quality control of the radioactive stents have been developed. Custom-made application software programmed in Visual Basic was used to control liquid flow and electroplating currents in the electrodeposition system, and to run the dual motion actuator and radiation detector for the automated measurement of the radioactivity distribution. The automation of the electroplating process increased the precision, ease, repeatability, and radiation safety of the process. The radioactive beta-emitting 188Re stents might be useful for the treatment of patients with inoperable lung cancer.

Brachytherapy↗
PubMed2006

Radioactive sputter cathodes for 32P plasma-based ion implantation.

The development of clinical treatments involving the use of beta-emitting millimetric and sub-millimetric devices has been a continuing trend in nuclear medicine. Implanted a few nanometers below the surface of endovascular implants, seeds or beads, beta-emitting radioisotopes can be used in a variety of biomedical applications. Recently, new technologies have emerged to enable the rapid and efficient activation of such devices. A pulsed, coaxial electron cyclotron resonance plasma reactor was designed and tested to demonstrate the feasibility of plasma-based radioactive ion implantation (PBRII). It has been shown that such plasma reactors allow for the implantation of radioisotopes (32P) into biomedical devices with higher efficiencies than those obtained with conventional ion beams. Fragments containing radioactive atoms are produced in the implanter by means of a negatively biased solid sputter cathode that is inserted into an argon plasma. Dilute orthophosphoric acid solutions (H3(32)PO4) are used for the fabrication of flat sputter targets, since they offer a high radioisotope content. However, the aggregation of the radioactive solute into highly hygroscopic ring-like deposits rather than flat, thin radioactive films is observed on certain substrates. This article describes the effect of this nonuniform distribution of the radioisotopes on the efficiency of PBRII, and presents a technique which enables a better distribution of 32P by coating the substrates with iron. The iron coating is shown to enable optimal radioisotope sputtering rates, which are essential in 32P-PBRII for the efficient activation of millimetric biomedical devices such as stents or coils.

Gold↗
PubMed1973

The excess radioactivity of trypsin mixtures.

The radioactivities of mixtures of trypsin and HB(3)O(3) or LiCl have been measured and compared with the radioactivity of the constituents. No evidence was found for the production of heavy particles, as had been previously reported, neither were the excess counting rates of the mixtures over that of its constituents as large. The residual excess radioactivity was about four orders of magnitude smaller than that published, yet was still statistically significant, consisting mainly of electrons having a maximum energy less than about 400 keV. The excess radioactivity of a mixture of trypsin and LiCl had a probable half-life between 5 and 46 days. Possible mechanisms for these excesses are discussed.

Absorption↗
PubMed1988

Method for evaluating the bioconversion of radioactive polyunsaturated fatty acids by use of reversed-phase liquid chromatography.

Reversed-phase high-performance liquid chromatography on a thermostatted octadecylsilyl column was used to separate mixtures of labelled polyunsaturated fatty acids (as their methyl esters) formed by successive desaturations and elongations of labelled linoleic (18:2 n - 6) or linolenic (18:3 n - 3) acid by rat liver microsomes. Acetonitrile-water mixtures were used for elution of the esters. Unsaturated and saturated esters were detected by their refractive indices. The order of elution of fatty acid methyl esters in complex mixtures varies as a function of the chain length and unsaturation, analysis temperature, water concentration and solvent flow-rate. The peak areas vary as a function of the unsaturation. Specific radioactivities of 14C-labelled fatty acids and the percentage distribution of radioactivity among fatty acids from complex mixtures can be efficiently determined by collection and direct measurement of the radioactivity in the solvent by liquid scintillation counting. The method can be applied to complete compositional analysis, but is especially useful for determination of specific radioactivities during studies on the metabolic conversion of labelled polyunsaturated fatty acids.

Chromatography, Gas↗
PubMed2000

Radioactive plaque therapy for metastatic choroidal carcinoma.

PURPOSE: To describe the outcome of radioactive episcleral plaque therapy for treatment of metastatic carcinoma to the choroid. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Five patients (six eyes) with carcinoma metastatic to the choroid. METHODS: Retrospective review of the clinical records of five patients (six eyes) who underwent radioactive episcleral plaque therapy for choroidal metastases. MAIN OUTCOME MEASURES: Tumor height, visual acuity, radiation optic neuropathy, and radiation retinopathy. RESULTS: Radioactive episcleral plaque therapy resulted in shrinkage of the treated tumors and resolution of subretinal fluid in all eyes. After plaque treatment, best-corrected visual acuity was maintained within two lines of initial visual acuity for two eyes, decreased more than two lines for one eye, and improved more than two lines in three eyes. The treatment was well tolerated and there was no acute toxicity. Late complications included optic nerve atrophy (at 2 years) with proliferative radiation retinopathy (at 3 years) in one eye and optic atrophy (at 6 months) in another eye that had received prior external beam therapy. CONCLUSIONS: In carefully selected cases, radioactive episcleral plaque therapy appears to be an effective and reasonable treatment for carcinoma metastatic to the choroid.

Adenocarcinoma↗
PubMed1987

Non-radioactive hepatitis B virus DNA probe for detection of HBV-DNA in serum.

A diagnostic test has been developed to detect hepatitis B virus (HBV) DNA in human sera. This test involves a dot-blot technique in which non-radioactive nucleic acid labelled with 2-acetylaminofluorene (AAF) is used as probe. Two series of human sera from 228 blood donors and 113 HBsAg chronic carriers were tested by hybridization with the same DNA probe labelled either with AAF or with 32P. A correlation between the techniques was observed for 328 sera (96%), and using the non-radioactive test it was possible to detect 56 (86%) of the 65 HBV-DNA-positive patients. A comparative study of the HBeAg/anti-HBe status and the presence of HBV-DNA was carried out on the sera from 113 HBsAg chronic carriers, 65 of which were positive for HBeAg and 29 of which were positive for anti-HBe antibodies. With the AAF test, 44 of the HBeAg-positive sera were positive, while 5 of the anti-HBe-positive sera were positive. This study shows that, although this non-radioactive test is slightly less sensitive than the radioactive hybridization assay (RHA), it can be used for a survey of HBV carriers. Dissociation of the viral multiplication and the HBe/anti-HBe status was identified with the AAF test as well as with the RHA. It would therefore appear that the AAF test described here may be used for the extensive survey of HBV multiplication.

2-Acetylaminofluorene↗
PubMed1997

Transperineal ultrasound-guided radioactive seed implantation for organ-confined carcinoma of the prostate.

PURPOSE: This retrospective study was undertaken to: (a) determine the prognostic significance of pretreatment and 1-year nadir serum prostate specific antigen (PSA) levels in organ-confined carcinoma of the prostate treated with ultrasound-guided radioactive 125I seed implantation; (b) determine the factors associated with postimplant morbidity and whether modification of the technique would reduce morbidity; (c) evaluate the local control rate and disease-free survival of patients undergoing seed implantation. METHODS AND MATERIALS: From October 1988 through December 1992, 142 patients with organ-confined adenocarcinoma of the prostate and a Gleason score < or = 7 underwent ultrasound-guided radioactive 125I seed implantation as an alternative to radical prostatectomy. Patients were considered to have persistent or progressive disease if there was evidence of local progression on digital exam, or if there were two consecutive increases in the PSA level. Patients suspected of persistent or progressive disease underwent restaging to include CT scan of the pelvis, bone scan, and ultrasound-guided prostate biopsy. Patients with increasing PSA levels in which active disease could not be confirmed were considered biochemical failures with occult systemic disease and were offered hormone ablation. RESULTS: With 1-6-year follow-up, median 30 months, the relapse patterns were prostate 4 (2.8%), bone 4 (2.8%), rising PSA 16 (11%). Pretreatment PSA level correlated with subsequent recurrence; pretreatment PSA < or = 4 (0), 4.1 to 10 (14%), 10.1 to 20 (21%), 20.1 to 50 (58%). Disease free survival at 2 years was 90% and at 5 years 76%. Nadir PSA (nPSA) at 1 year also correlated with recurrence: nPSA < or = 1 (3%), nPSA 1 < or = 4 (50%), and nPSA > or = 4 (100%). Seed implantation was well tolerated with 31% of patients experiencing RTOG morbidity > or = Grade 2, which typically consisted of transient radiation urethritis, which resolved with conservative measures. Eleven (8%) experienced RTOG morbidity > or = Grade 3. There was no correlation between number of seeds or total millicuries implanted and subsequent morbidity. However, reduction in the periurethral seed intensity reduced > or = Grade 3 morbidity from 11 to 4%. CONCLUSION: Ultrasound-guided radioactive seed implantation provides excellent local control of 97%, with a median 30 month follow-up. Morbidity is comparable to other curative modalities and by modifying Blasko's technique to reduce radioactive seed strength in the periurethral area, significant morbidity is rare. Pretreatment PSA and the nadir PSA at 1 year are important predictors of subsequent disease outcome. With a liberal definition of systemic recurrence as two consecutive increases in PSA levels, the 5-year disease-free survival is 76%.

Aged↗
PubMed1998

Current status of radioactive stents for the prevention of in-stent restenosis.

PURPOSE: The objective of this paper was to provide an update on the clinical and experimental evaluation of radioactive stents for the prevention of restenosis. MATERIALS AND METHODS: Direct ion implantation of 32P onto the surface of a 15-mm length balloon expandable stainless-steel Palmaz-Schatz stent was employed to render this commercially available vascular stent radioactive. 32Phosphorous, a pure beta-particle-emitting radioisotope, was selected because of its short half-life (14.3 days) and limited range of tissue penetration (3-4 mm). The vascular response to radioactive 7-mm length Palmaz-Schatz stents with activities 0.14 to 23 microCi of 32P were evaluated in animal models of arterial injury and restenosis. The Phase-1 isostent for restenosis intervention study (IRIS trial) was a nonrandomized safety trial designed to evaluate the use of a low activity 32P (0.5 to 1.5 microCi) 15-mm length Palmaz-Schatz stent for the treatment of de novo or restenosis native coronary arterial lesions. RESULTS: In the porcine coronary restenosis model, at < or =0.5 microCi and > or =3.0 microCi stent activities, there was a 30% reduction in the neointimal and percent area stenosis as compared to nonradioactive stents. The 1.0 microCi stents, however, had nearly 2-fold greater neointimal formation and more luminal narrowing than the control stents. In the Phase 1 IRIS trial, 57 patients with symptomatic de novo or restenosis native coronary lesions have been treated with low activity (0.5 to 1.5 microCi) 32P Palmaz-Schatz coronary stents. Fifty-seven stents were successfully implanted without a major procedural complication (death, urgent coronary bypass, Q-wave myocardial infarction). There were no cases of stent thrombosis, target vessel revascularization, or other adverse events in the first 30 days after implant. CONCLUSION: The early clinical results with a low-activity 32P Palmaz-Schatz radioactive stent demonstrate sufficient procedural and 30-day event-free survival to warrant consideration of additional clinical studies to determine the safety and efficacy of this therapy for the prevention of restenosis. Future studies will focus on optimal stent design for delivery of radiation, and will further evaluate safe and effective dosing strategies.

Animals↗
PubMed2002

Optimal design of radioactive particle tracking experiments for flow mapping in opaque multiphase reactors.

In the past decade, radioactive particle tracking techniques have emerged in the field of chemical engineering and have become increasingly popular for non-invasive flow mapping of the hydrodynamics in multiphase reactors. Based on gamma-ray sensitization of an array of scintillation detectors, the Computer Automated Radioactive Particle Tracking (CARPT) technique measures flow fields by monitoring the actual motion path of a single discrete radioactive flow follower which has the physical properties of the phase whose motion is being followed. A limitation to the accuracy of CARPT lies in the error associated with the reconstruction of the tracer particle position which affects the space-resolution capability of the technique. It is of interest, therefore, to minimize this error by choosing wisely the best hardware and an optimal configuration of CARPT detectors' array. Such choices are currently based on experience, without firm scientific basis. In this paper, through theoretical modeling and simulation, we describe how the accuracy of a radioactive particle tracking setup may be assessed a priori. Through an example of a proposed implementation of CARPT on a gas-solids riser, we demonstrate how this knowledge can be used for choosing the hardware required for the experiment. Finally, we show how the optimal arrangement of detectors can be effected for maximum accuracy for a given amount of monetary investment for the experiment.

Journal Article↗
PubMed2002

Study of radioactivity levels in granite of Gable Gattar II in the north eastern desert of Egypt.

The present work deals with the radioactivity of granites in Gable Gattar II, which is located in the north eastern desert of Egypt. Fifty samples from the area of Gable Gattar II were investigated. The radionuclides of the samples, in Bq/kg, have been measured using a hyper-pure germanium spectrometer. The dose obtained for 238U and 232Th ranged from 165 +/- 5 to 27,851 +/- 836 and 71 +/- 2 to 274 +/- 8 Bq/kg, respectively. The dose of 40K only changes slightly. To assess the radiological hazard of the natural radioactivity in the samples, the radium equivalent activity, the absorbed dose rate and the external hazard index were calculated. This study provides a baseline map of radioactivity background levels in the Egyptian environment and will be used as reference information to assess any changes in the radioactive background level due to geological processes. The Gable Gattar granite, from uranium mineralization, has high economic potential.

Journal Article↗
PubMed2000

In-target production of high specific radioactivity [15O]nitrous oxide by deuteron irradiation of nitrogen gas.

A simple and rapid production method for high specific radioactivity [15O]N2O has been developed based on the 14N(d,n)15O reaction on high-purity nitrogen gas in a flow-through target irradiated with a 0.5 microA beam of 7 MeV deuterons. The [15O]N2O formed during irradiation is selectively concentrated from the target effluent by adsorption on a zeolite during 150 s and subsequently released by rapid heating into a pulse with a full width at half maximum of 3.5 s. The radioactivity and specific radioactivity in the pulse amount to 4 MBq [15O]N2O and 4.5 x 10(13) Bq/mol respectively with a radiochemical purity >99.95%. A tenfold higher specific radioactivity may be feasible at larger beam currents. It was shown that stable N2O was also formed during irradiation. Based on responses to variations in various parameters during irradiation and on analyses performed on the products, an explanation is given on the mechanisms of in-target [15O]N2O and N2O formation, involving reaction of a particular excited state of O3 with N2.

Journal Article↗
PubMed2001

Significance of (111)In-DTPA chelate in renal radioactivity levels of (111)In-DTPA-conjugated peptides.

Metabolic studies of (111)In-DTPA-labeled polypeptides and peptides showed that the radiolabeled (poly)peptides generated (111)In-DTPA-adducts of amino acid that possess long residence times in the lysosomal compartment of the tissues where (poly)peptides accumulated. However, a recent study suggested that metal-chelate-methionine (Met) might possess in vivo behaviors different from metal-chelate adducts of other amino acids. In this study, to elucidate whether some biological characteristics of Met may accelerate the renal elimination rate of (111)In-DTPA-adduct of Met into urine, (111)In-DTPA-Met(1)-octreotide was synthesized and the renal handling of (111)In-DTPA-Met was investigated using (111)In-DTPA-L-Phe(1)-octreotide (Phe represents phenylalanine), which was reported previously, as a reference. Both (111)In-DTPA-conjugated octreotide analogs were stable against 3-h incubation in murine serum at 37 degrees C. Both (111)In-DTPA-octreotide analogs also showed rapid clearance of the radioactivity from the blood and similar accumulation of the radioactivity in the kidney. No significant differences were observed in the renal radioactivity levels from 10 min to 24 h postinjection between the two. Metabolic studies indicated that (111)In-DTPA-Met(1)-octreotide and (111)In-DTPA-L-Phe(1)-octreotide generated (111)In-DTPA-adducts of Met and Phe, respectively, as the final radiometabolites at similar rates. These findings suggested that the long residence times of the radioactivity in tissues after administration of (111)In-DTPA-labeled peptides and polypeptides would be attributed to inherent characteristics of (111)In-DTPA chelate.

Animals↗
PubMed1996

An alternative to radioactive microspheres for measuring regional myocardial blood flow, Part 1: Colored microspheres.

OBJECTIVE: To compare measurements of regional myocardial blood flow between color and radioactive microspheres. DESIGN: Prospective, randomized, controlled. SETTING: University research laboratory. PARTICIPANTS: Pigs. INTERVENTIONS: Pigs underwent constriction of the left anterior descending artery, either incremental and then 0 constriction with epinephrine, 0.5 to 3 mu/kg/min (n = 5; "variable") or only 0% and 100% constriction without epinephrine (n = 4, "single"). Radioactive and color microspheres were injected simultaneously. For variable constriction, 5 colors (3 x 10(6)/mL) were tested in random order and, for single, red and yellow (6 x 10(6)/2 mL). MEASUREMENTS AND MAIN RESULTS: Measurements of regional endocardial, epicardial, and transmural myocardial blood flow were compared by regression analysis (linear and nonlinear). With radioactive measurements as the point of reference, when regional flow was 50 to 150 mL/min/100 g, correlation was high (r = 0.85), although regression slope was low. With endocardial and epicardial flow between 30 and 100 mL/min/100 g, correlation was close (r = 0.84). Overall nonlinear correlation was higher with single than variable constriction (r = 0.72). When regional flow was less than 100 mL/min/100 g, linear correlation was r = 0.72. When transmural flow measured by color microspheres was less than 25 mL/min/100 g, correlation was high (r = 0.86) but, with endocardial or epicardial flow, low (r = 0.67). When transmural flow was greater than 100 mL/min/100 g, correlation was extremely low (r = 0.1; n = 26 data points). The overall correlations for regional endocardial and epicardial flows were also low, except in the ischemic zone. CONCLUSIONS: Color and radioactive measurements correlate well during moderate and ischemic regional myocardial blood flow, ischemic blood flow requiring a higher concentration of color microspheres. A major limitation of using color microspheres is imprecision when flow is greater than 150 mL/min 100 g.

Animals↗
PubMed2003

Combination of high-performance liquid chromatography and microplate scintillation counting for crop and animal metabolism studies: a comparison with classical on-line and thin-layer chromatography radioactivity detection.

Samples from crop or animal metabolism studies of pesticides were used to evaluate the performance of the combination of analytical or narrow-bore HPLC and microplate scintillation counting (TopCount). Samples with extreme matrix content such as grain and tomato extracts from crop metabolism studies as well as extracts from hen excreta or goat urine from farm animal metabolism studies could be injected, analyzed, and quantified directly without any sample pretreatment. The minimum amount of radioactivity injected was approximately 1 Bq (60 dpm). Counting times from 5 to 60 min were used for detection and quantification. These results were compared with those from classical on-line radioactivity detection and with radioactivity detection on thin-layer chromatography plates.The combination of analytical or narrow-bore HPLC and microplate scintillation counting (TopCount) offers high sensitivity and high resolution power at the same time. It could be clearly demonstrated that the combination of HPLC with microplate scintillation counting is superior to the classical on-line radioactivity detection and at least equivalent to the classical thin-layer radiochromatography regarding performance and sensitivity.

Animals↗
PubMedDate not supplied

Control of radioactivity pharmacokinetics of 99mTc-HYNIC-labeled polypeptides derivatized with ternary ligand complexes.

An enhancement of the target/nontarget ratio of radioactivity levels enables reliable diagnosis and therapy using polypeptide radiopharmaceuticals in nuclear medicine. In the present study, we investigated the effects of the physicochemical properties of radiometabolites on the radioactivity pharmacokinetics after administration of 99mTc-labeled polypeptides using 6-hydrazinopyridine-3-carboxylic acid (HYNIC). Four ternary ligands (L) [3-benzoylpyridine (BP), 3-acetylpyridine (AP), 3-nicotinic acid (NIC), pyridine (PY)] with different lipophilicity were selected as coligands for the preparation of 99mTc-HYNIC-polypeptides. Each of the ternary ligands tested provided 99mTc-HYNIC-labeled galactosyl-neoalbumin (NGA) and Fab fragments of high stability with high radiochemical purity. Moreover, after administration of each 99mTc-HYNIC-labeled NGA into normal mice, the respective ternary ligand [99mTc](HYNIC-lysine)(tricine)(L) complexes were generated as final radiometabolites in the hepatic lysosome. The partition coefficients of [99mTc](HYNIC-lysine)(tricine)(BP), [99mTc](HYNIC-lysine)(tricine)(AP), [99mTc](HYNIC-lysine)(tricine)(NIC), and [99mTc](HYNIC-lysine)(tricine)(PY) were determined to be -2.21, -2.37, -2.93, and -2.73, respectively. Elimination rates of these radiometabolites from the lysosome were enhanced in the order of increasing lipophilicity of the radiometabolites. After injection of the four 99mTc-HYNIC-labeled Fab fragments into normal mice, blood clearances of radioactivity were similar while radioactivity elimination rates from the kidney were enhanced in the order of increasing lipophilicity of the radiometabolites. The present study indicated that the lipophilicity of the radiometabolites constitutes one important factor affecting their elimination rates from the tissues. Thus, as ternary ligands facilitate alteration of the physicochemical properties of radiometabolites, the use of ternary ligand complexes might be applicable for controlling the pharmacokinetics of 99mTc-labeled polypeptides.

Albumins↗
PubMedDate not supplied

In vitro system to estimate renal brush border enzyme-mediated cleavage of Peptide linkages for designing radiolabeled antibody fragments of low renal radioactivity levels.

Renal localization of radiolabeled antibody fragments presents a problem in targeted imaging and radiotherapy. We recently reported that Fab fragments labeled with 3'-[(131)I]iodohippuryl N(epsilon)-maleoyl-l-lysine (HML) demonstrated markedly low renal radioactivity levels from early postinjection in mice. Previous studies suggested that low renal radioactivity levels were attributable to cleavage of the glycyl-lysine sequence in HML by the action of renal brush border enzymes, followed by urinary excretion of the resulting m-iodohippuric acid. In this study, an in vitro system using brush border membrane vesicles (BBMVs) isolated from the rat kidney cortex was developed to estimate renal brush border enzyme(s)-mediated cleavage of the peptide linkage. Low molecular weight HML derivatives, 3'-[(125)I]iodohippuryl l-lysine (HL), 3'-[(125)I]iodohippuryl N(epsilon)-tert-butoxycarbonyl-l-lysine (HBL), and their d-amino acid counterparts, were synthesized and incubated in BBMVs. Both [(125)I]HL and [(125)I]HBL generated m-[(125)I]iodohippuric acid after incubation in BBMVs at 37 degrees C while the latter liberated significantly higher amounts of the metabolite. [(125)I]d-HL and [(125)I]d-HBL failed to release the metabolite under similar conditions. The liberation of m-[(125)I]iodohippric acid from [(125)I]HL was significantly facilitated or completely inhibited by the addition of an activator or an inhibitor for carboxypeptidase M. The release of m-[(125)I]iodohippuric acid from [(125)I]HBL increased by the addition of the activator, whereas the inhibitor partially inhibited the release of the metabolite from [(125)I]HBL. The BBMV-mediated release of m-[(125)I]iodohippuric acid from [(125)I]HBL was not impaired by the addition of inhibitors for neutral endopeptidase or renal dipeptidase. These findings showed that the glycyl-l-lysine sequence in HML would be recognized and cleaved by metalloenzymes and nonmetalloenzymes on the renal brush border even when iodine was incorporated into a benzene ring and the N(epsilon)-amine residue of lysine was chemically modified, which supported the hypothesis that low renal radioactivity levels of HML-conjugated Fab fragments would be attributed to the release of m-iodohippuric acid by renal brush border enzymes. This study suggested that this in vitro system using BBMVs would be useful to estimate radiolabeling reagents of antibody fragments or peptides designed to reduce renal radioactivity with a variety of radionuclides.

Amino Acid Sequence↗
PubMed2006

Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in growing swine.

An experimental chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of chlorate as a preharvest food safety tool in swine merits consideration.

Animals↗
PubMed2004

Degradation of the radioactive and non-labelled branched 4(3',5'-dimethyl 3'-heptyl)-phenol nonylphenol isomer by sphingomonas TTNP3.

The degradation of the 4(3',5'-dimethyl-3'-heptyl)-phenol (p353NP) nonylphenol isomer in cultures of Sphingomonas TTNP3 supplemented with the technical mixture of nonylphenol was first assessed. Then the radioactive and non-labelled form of these diastereomers were both synthesised. The radioactive isomers were synthesised using [ring-U-14C]-labelled phenol and 3,5-dimethyl-3-heptanol by Friedel and Crafts alkylation. The time-course of degradation was performed with and without 14C-p353NP; balancing of radioactivity was calculated from different soluble fractions (organic, aqueous), bacterial biomass, and 14CO2 evolved as mineralization product. The noticeable portion of 14C bound to biomass showed that at least the aromatic ring of 14C-p353NP was degraded and served as energy source and probably as carbon source for bacterial growth. In addition, the appearance of 3,5-dimethyl-3-heptanol, the nonanol corresponding with the side-chain of p353NP, was demonstrated in the bacterial media, and its concentration determined during the course of fermentation. Besides the parent 14C-p353NP, no other radioactive compounds, i.e. metabolites of 14C-p353NP were detected in the media.

Biodegradation, Environmental↗