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PubMed2002

Flumequine in Atlantic salmon Salmo salar: disposition in fish held in sea water versus fresh water.

14C-labeled flumequine was administered as a single oral (5 mg kg(-1), 86 microCi kg(-1)) or intravenous (5 mg kg(-1), 82 microCi kg(-1)) dose to Atlantic salmon Salmo salar held in sea water or in fresh water. The absorption, tissue distribution and elimination were determined by means of liquid scintillation counting and whole-body autoradiography. The drug was rapidly absorbed and extensively distributed in all groups of fish. Radiolabeled compound was present in blood and muscle for more than 8 wk in the freshwater groups. In the seawater groups, however, no radioactivity was detected in the blood and muscle after 4 d and 2 wk, respectively. It was concluded that flumequine was eliminated at a substantially higher rate from Atlantic salmon in sea water than in fresh water.

Absorption↗

PubMed1987

Improved method for the measurement of ribonucleotide reductase activity.

An improved method for the measurement of herpes simplex virus type 1 encoded ribonucleotide reductase has been developed. The enzyme which catalyses the conversion of ribonucleoside diphosphates to deoxyribonucleoside diphosphates was determined by first converting the ribonucleotide substrate and deoxyribonucleotide product to the corresponding nucleosides by treatment with snake venom phosphodiesterase. Then nucleosides were separated by HPLC and measured by flow through scintillation counting and by monitoring their absorbance at 254 nm. Under the conditions used in the experiment cytidine and deoxcytidine, the derivitised substrate and product respectively, eluted from the column at approximately 4 min 33 s and 6 min 24 s. Peak heights and areas were automatically calculated by computer to ascertain the amount of product formed and thus quantitate the assay. Automation of the assay from sample injection to analysis provides a significant saving in time and an improvement in the efficiency of measurement of ribonucleotide reductase activity over other published methods.

Chromatography, High Pressure Liquid↗

PubMed2002

[Radon 222Rn in drinking water of Izera Plateau].

Radon-222 concentration in surface water, wells water and tap water in the main towns and villages which are located in area of Izera Plateau has been quantitative determined. The measurements were performed using the alpha liquid scintillation counting method. The main waterworks in Szklarska Poreba is supplied with the surface water in which the radon concentration is low: from 1.23 Bq/l to 4.32 Bq/l. Waterworks "Huta Julia" is supplied with the ground water have a high radon concentration: from 294.4 Bq/l to 319.5 Bq/l. Majority of waterworks in Izera Plateau is supplied with the ground water in which the radon concentration is high: from 113.3 Bq/l to 464.5 Bq/l. The appropriate mean value for water of individual wells was 253.0 Bq/l, within the range from 25.8 Bq/l to 1095.1 Bq/l.

Carcinogens, Environmental↗

PubMed1986

A method for the determination of tritium in environmental water samples by electrolytic enrichment.

In order to determine the tritium concentration in environmental water samples, the electrolytic enrichment was carried out with (St) and without (S) addition of tritiated water of a certain concentration (deuterium-free) to the samples. With the use of the fundamental formulas on electrolytic enrichment, the deuterium concentration (Dit) before electrolysis for an environmental water sample is determined by liquid scintillation counting and densitometry for the sample St. Furthermore, the tritium concentration in the environmental water sample is determined by the above methods for the sample S, and by the substitution of Dit for Di in the formulas. Tritium concentrations in environmental water samples were found to be determined within an accuracy of 10% by this method when Vi/Vf was 14-25. It is considered that this method dispenses with the direct measurement of low deuterium concentrations (Di) before electrolysis, a special technique on the purification of water for densitometry, and moreover, excludes the possibility of cross contamination in the electrolytic enrichment by the spike cell method.

Densitometry↗

PubMed1979

The role of liver passage for conversion of pteroylmonoglutamate and pteroyltriglutamate to active folate coenzyme.

In an attempt to clarify the possible site of conversion of folates to active methylated coenzyme forms mono- and triglutamate was injected rapidly into the portal vein of dogs. Samples of blood were removed at various intervals from catheters placed in the portal vein, the hepatic vein and the femoral artery for assay carried out both with L. casei, S. Faecalis and liquid scintillating counting. Unreduced monoglutamates were extracted in the liver, immediately converted to methyltetrahydrofolate and released again to plasma from which it was slowly taken up by peripheral tissue. Reduced folates were refused by the liver. Triglutamates were extracted exclusively in the systemic circulation, converted to unreduced monoglutamate later to be reduced in the liver. No tissue displacement of folate was demonstrated. Only small amounts of monoglutamates, mainly reduced forms, were lost in the urine during the experiments. The kinetics of unreduced monoglutamate suggest a one compartment system, while the kinetics of methyltetrahydrofolate and triglutamate may implicate a two compartment system.

Animals↗

PubMed2006

Performance characteristics of sequential separation and quantification of lead-210 and polonium-210 by ion exchange chromatography and nuclear spectrometric measurements.

A selective separation and quantitative determination procedure for 210Pb and 210Po in various environmental matrices from different sources such as IAEA-326 soil, phosphate rocks (PR), and phosphogypsum (PG) was developed. The tested samples were digested sequentially using concentrated mineral acids (HF, HNO3) by a programmable high-pressure microwave digestion system. The sample solution was loaded onto a preconditioned ion exchange column (Sr-resin) for chromatographic separation. Polonium-210 was eluted by 6 M HNO3 then spontaneously deposited onto polished silver discs to be measured using low-background alpha spectrometry. Lead-210 was sequentially eluted using 6 M HCl solution, precipitated as lead oxalate, dissolved in HNO3 solution, and mixed with scintillation cocktail to be measured by liquid scintillation counting (LSC). Performance of the developed procedure was tested using a reference soil (IAEA-326), with recommended isotope values, that was used as a quality control to assess separation and quantification efficiency (recovery %). The minimum detectable activities of 210Pb and 210Po were found to be 24 and 0.28 Bq kg(-1) for the measurements using LSC and alpha spectrometry, respectively. The recoveries (%) of 210Pb and 210Po were found to be 80 and 60%, respectively. To test the validity of the proposed LSC method, a comparative study was performed by measuring 210Pb activity concentration in test samples by nondestructive gamma-ray spectrometry.

Calcium Sulfate↗

PubMed2002

Determination of ferrichrome binding to the FhuA outer membrane transport protein, periplasmic accumulation of ferrichrome, or transport of ferrichrome into cells using a three-layer oil technique.

A new method for the determination of ferrichrome binding to the FhuA transporter in the Escherichia coli outer membrane, ferrichrome accumulation in the periplasmic space, and ferrichrome transport into the cytoplasm was developed. Cells were separated from residual, soluble, radiolabeled ferrichrome by centrifugation in a micro-test tube containing three layers of nonmixable solutions of different densities. Cells in the upper aqueous layer passed through the middle silicone oil layer, but did not enter the underlying NaI layer, thereby accumulating on top of the NaI layer; soluble compounds remained in the upper aqueous layer. Cells were then easily recovered by centrifugation, and radioactivity was determined by liquid scintillation counting. Reproducible results for all applications tested were obtained without the need for any washing steps. The method was tested by determination of receptor binding and transport of ferrichrome with various FhuA mutants which, in contrast to their transport activity, showed only a weak binding of ferrichrome to FhuA and compared with the commonly used cellulose nitrate filter method. Similar transport rates were obtained with the two methods, but binding of ferrichrome to the mutated FhuA proteins and accumulation of ferrichrome in the periplasm could be measured only with the new method.

Bacterial Outer Membrane Proteins↗

PubMed1983

The relationship between 8-methoxypsoralen skin and blood levels.

A method is described to determine the 8-methoxypsoralen (8-MOP) concentration in vivo in the skin by means of high-performance liquid chromatography (HPLC). Skin and blood samples were taken from 80 rats at specific intervals after oral administration of [3H]8-MOP. The pharmacokinetic results obtained for the skin levels were compared to the blood levels. In addition, liquid scintillation counting (LSC) was done on all the samples to compare the concentrations of 8-MOP plus metabolites to the concentrations of 8-MOP alone. There was a good correlation between the 8-MOP skin and blood levels. The values obtained with LSC were higher in function of time than the corresponding values obtained by HPLC, which indicates the presence of metabolites in both the skin and the blood. No statistically significant difference in the time of peaking was noted for the skin and blood levels. The blood levels seem to be a good parameter for the 8-MOP skin concentration.

Administration, Oral↗

PubMed2001

In vivo degradation of 14C-labeled small intestinal submucosa (SIS) when used for urinary bladder repair.

The rate of in vivo degradation was determined for a naturally occurring biomaterial derived from the extracellular matrix of the small intestinal submucosa (SIS). The SIS was labeled by giving weekly intravenous injections of 10 microCi of 14C-proline to piglets from 3 weeks of age until the time of sacrifice at 26 weeks. The resultant SIS prepared from these pigs contained approximately 10(3) fold more 14C than unlabeled tissues. The labeled SIS was used to repair experimental defects in the urinary bladder of 10 dogs. The animals were sacrificed at post-operative times ranging from 3 days to 1 year and the remodeled urinary bladder tissue was harvested for evaluation of 14C by a combination of liquid scintillation counting and accelerator mass spectrometry. The remodeled tissue contained less than 10% of the 14C (disintegrations per minute/gram tissue wet weight) at 3 months post-surgery compared to the SIS biomaterial that was originally implanted. The SIS scaffold was replaced by host tissue that resembled normal bladder both in structure and function. After implantation, 14C was detected in highest concentrations in the blood and the urine. The SIS bioscaffold provides a temporary scaffold for tissue remodeling with rapid host tissue remodeling, degradation, and elimination via the urine when used as a urinary bladder repair device.

Animals↗

PubMed2003

14C-methylamine-glutaraldehyde conjugation as an alternative to iodination for protein labeling.

Radiolabeling of native proteins conventionally has required iodination using 125Iodine (125I). Although radioiodination can result in high specific activity, there are several drawbacks in the use of 125I (e.g., radiological hazards and short half-life). 14C-Methylamine-glutaraldehyde conjugation to proteins offers an alternative for radiolabeling of proteins that is safer and longer-lived alpha-2-Macroglobulin was radiolabeled by conjugation to a 14C-methylamine-glutaraldehyde conjugate. Analysis of the labeling procedure was performed using scintillation counting, gel filtration chromatography, and protein assays. The radiolabeled alpha-2-macroglobulin was activated using established protocols and tested for functional integrity using competitive binding assays in the presence of recombinant receptor associated protein, an alternative ligand for the alpha-2-macroglobulin cellular receptor. The function of alpha-2-macroglobulin was unaffected by the labeling procedure. Comparison of 14C-methylamine-labeling and iodination by Scatchard analysis yielded nonlinear plots that suggested the presence of two sets of receptors with different binding affinities but that do not show cooperativity. This technique offers an alternative to radioiodination for the sensitive labeling of proteins.

Binding, Competitive↗

PubMed1994

Maintenance of the gliding surface of tendon autografts in dogs.

To determine whether there are differences in the extent to which the superficial cellular layers remain viable and contribute to the healing process, extra- and intrasynovial hindlimb donor tendons of 12 dogs (24 tendons) were labeled with 3H-thymidine in vitro and transferred to the medial and lateral toes of the forepaw. After transplantation, the distribution and amounts of remaining labeled cells within the healing tendon grafts were determined at 1 and 3 weeks after surgery by scintillation countings and autoradiographic examinations. The two types of tendon grafts showed different turnover rates for the elimination of labeled DNA. At 1 week, 25 percent of labeled DNA remained in the extrasynovial grafts and 65 percent in the intrasynovial grafts. The two types of tendon grafts also showed different healing responses histologically. Autradiographic examinations showed that the majority of labeled cells were located in the periphery of the control tendons and that the numbers of labeled cells within the newly proliferated superficial areas of both types of tendon grafts decreased over time. These findings indicate that intrasynovial flexor tendons may possess improved prerequisites for superficial cellular survival and tendon gliding following autogenous tendon grafting.

Animals↗

PubMed1993

Measurements of the gastrointestinal absorption and tissue distribution of plutonium, americium and polonium in experimental animals.

In order to set limits on environmental and occupational intakes of radionuclides, information is needed on their uptake and metabolism in man. Human data are very limited, particularly for long-lived alpha-emitting isotopes such as those of the actinides. Animal experiments are therefore an important source of data on the distribution of radionuclides in tissues, and the effects of factors such as subject age and the chemical form of elements on gastrointestinal absorption. The NRPB performs experimental programs using mainly rats and guinea pigs. In order to study the gastrointestinal absorption and tissue distribution of plutonium, americium and polonium, a variety of analytical techniques are employed. These include ion exchange and solvent extraction leading to alpha spectrometry and liquid scintillation counting. The investigation of low specific-activity environmental or industrial materials, and the very low bioavailability of elements such as the actinides, means that very low levels of activity have to be measured. Contamination at the dissection and tissue separation stage, as well as during the radiochemistry, has to be rigorously avoided. Where very detailed information is needed on the location of radionuclides within tissues, such as in the study of alpha-emitter distribution in the intestine, autoradiography is used. The application and relevance of different measurement techniques to animal studies will be discussed and examples of the results presented.

Aging↗

PubMed1980

Penetration of timolol into the rabbit eye. Measurements after ocular instillation and intravenous injection.

The distribution of radioactivity in 15 ocular and extraocular tissues or fluids of the rabbit after ocular instillation and intravenous injection of 100 microL of 14C-labeled timolol solution (1.5%) was studied by liquid scintillation counting (LSC). The drug was distributed rapidly among the tissues examined after both routes of administration. Levels of radioactivity were considerably greater in ocular tissues after instillation as compared with intravenous injection, whereas in extraocular tissues the levels were similar after both routes of administration. Using the same experimental protocol, aqueous humor and serum levels of unchanged timolol were measured by gas liquid chromatography. Comparisons with LSC studies indicated that, following ocular instillation, only unchanged timolol was present in aqueous humor, whereas both timolol and metabolites were present in serum. After intravenous administration, timolol was rapidly metabolized and metabolites appeared in the serum and aqueous humor.

Administration, Topical↗

PubMed2004

Traced studies on metabolism of astaxanthin in Atlantic salmon (Salmo salar).

The present studies were performed to investigate the metabolism of astaxanthin (Ax) in Atlantic salmon, especially in the liver of salmon. The investigations were undertaken in vivo salmon that were fed a diet containing 60 ppm 15, 15' 14C-labelled Ax prior to sacrifice. The samples of blood, bile, liver, gastrointestinal tract and contents, muscle, skin, remaining carcass and feces were taken for scintillation counting. The highest radioactivity (71.36%) of 14C-labelled Ax was found in the gastrointestinal contents and feces, 7.13% in the bile and 10.68% in the samples of liver, muscle, and skin at the end of the experiments. The metabolites of 14C-labelled Ax were extracted from the bile of the salmon and analyzed using thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC). Predominant 14C-labelled Ax and its cis-isomers were found and no conjugation of 14C-labelled Ax was observed. These results indicate that 14C-labelled Ax was not conjugated into larger colorless compound in Atlantic salmon liver.

Animals↗

PubMed1990

The effects of intraocular pressure elevation on optic nerve axonal transport in the monkey.

Blockage of axonal transport by intraocular pressure (IOP) elevation was studied quantitatively in monkey eyes, using liquid scintillation counting. After 5 h of IOP elevation (perfusion pressure of 30 mmHg), axonally transported protein was measured in the distal third of each optic nerve, which was divided into superotemporal, inferotemporal, superonasal, and inferonasal portions. The ratio of the amount of radioactive protein in each portion of the optic nerve to that in the whole optic nerve was calculated. In eyes with IOP elevation, the mean ratio for the temporal optic nerve was significantly lower than that for the nasal optic nerve. It appeared that axonal transport was not affected homogenously throughout the optic nerve but was more impaired by the temporal half of the optic nerve following IOP elevation.

Analysis of Variance↗

PubMed1977

The combined use of iron 52 and its contaminant iron 55 in studies of the bone marrow.

A liquid scintillation counting technique has been used to measure 55Fe incorporation into red blood cells with counting efficiencies of the order of 10% for 0.1 ml whole blood. Measurements have been carried out over a period of two weeks following the intravenous administration of the shortlived cyclotron produced 52Fe which contains 55Fe (half-life 2.6 years) as contaminant. 52Fe, with its short half-life of 8.2 hours and suitable gamma-ray emissions, is the isotope of choice for bone marrow imaging and short term ferrokinetic studies such as plasma clearance and early organ uptake of iron. However, long term iron utilization cannot be measured with this radionuclide alone. By exploiting the presence of 55Fe this limitation has now been overcome.

Adult↗

PubMed2001

Radon in public water supplies in Migdonia basin, Central Macedonia, Northern Greece.

The main objective of this work is the accurate measurement of radon concentration in the public water supplies of the Migdonia basin in Northern Greece. The main aim is to localize the sub-areas that present high radon concentrations in water and to inform the local authorities so that more detailed studies might be set up in these areas. About 80 samples from special bore holes and taps that supply the local population with fresh water were collected in order to obtain detailed radon measurements. For the analyses, a liquid scintillation counting system, using the Packard protocol for measuring radon in water, was employed. The results of the investigation show that radon concentrations in these public water supplies are significant. The concentrations ranged from background concentrations to 170 Bq x L(-1). The level of 50 Bq x L(-1) is exceeded in 23% of water supplies. These preliminary results with initial data interpretation and inter-comparison assessment are presented. These results of the analyses showed that elevated radon concentrations were detected in water samples from an area at the western part of the Lake Volvi, due probably to the local intense tectonism, and from a village above the Lake Koronia.

Fresh Water↗

PubMed1999

A radiochemical assay for beta-ureidopropionase using radiolabeled N-carbamyl-beta-alanine obtained via hydrolysis of [2-(14)C]5, 6-dihydrouracil.

A radiochemical assay was developed to measure the activity of beta-ureidopropionase in human liver homogenates which is based on the detection of the reaction product (14)CO(2) by liquid scintillation counting. Radiolabeled N-carbamyl-beta-alanine was prepared within 15 min by a simple hydrolysis of [2-(14)C]5, 6-dihydrouracil under alkaline conditions at 37 degrees C. The enzymatic reaction proved to be linear with time up to at least 3.5 h and protein concentrations up to at least 1 mg/ml. Human beta-ureidopropionase obeyed Michaelis-Menten kinetics with an apparent Km for N-carbamyl-beta-alanine of 15.5 +/- 1.9 microM. The assay proved to be very accurate and sensitive with an intraassay coefficient of variation of 2% and a detection limit of 28 pmol for the product CO(2).

Amidohydrolases↗