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At least 613 records · Page 34Linked to original sources
PubMed1997

A dual-marker system for quantitative studies of myoblast transplantation in the mouse.

BACKGROUND: Myoblast transplantation (MT) is a potential approach for gene transfer into skeletal muscle, the efficiency of which depends upon the number of copies of donor genome incorporated into the host tissue. We have developed a system for quantitative studies of MT that measures amounts of donor-derived genome in host muscles and estimates the contributions of donor cell survival and proliferation in vivo. METHODS: [14C]thymidine-labeled, male myoblasts were transplanted into female muscles, providing two donor cell markers, Y chromosome and [14C]. The markers were measured in muscle extracts by slot blotting and scintillation counting, respectively. RESULTS: In each extract, the amount of Y chromosome was used to quantify donor-derived genome, whereas the radiolabel provided an estimate of cell survival. Furthermore, the different modes of inheritance of the markers meant that proliferation of surviving donor cells was detected as a change in marker ratio. CONCLUSIONS: This system provides a method for assessing potential improvements of MT.

Animals↗
PubMed2006

The evaluation of uncertainty in low-level LSC measurements of water samples.

The uncertainty in measurements of gross alpha and beta activities in water samples by liquid scintillation counting with alpha/beta discrimination has been evaluated considering the problems typical of low-level measurements of environmental samples. The use of a pulse shape analysis device to discriminate alpha and beta events introduces a correlation between some of the input quantities, and it has to be considered. Main contributors to total uncertainty have been assessed by specifically designed experimental tests. Results have been fully examined and discussed.

Alpha Particles↗
PubMed1979

[Determination of radioactive and stable cobalt in marine biological materials (author's transl)].

Studies were made to develop the method for rapid determination of radioactive and stable cobalt in a single specimen of marine biological materials. The sample was dried, ashed, and dissolved in acid. The cobalt was extracted with 1-nitroso-2-naphthol benzene and determined by absorptiometry on the benzene phase. Then, the organic solution was evaporated to dryness, and the residue was treated with nitric-perchloric acid mixture to decompose any organic matter, and taken up with hydrochloric acid. The cobolt was extracted from the solution with TIO A-toluene, and the radioactive cobalt was determined by liquid scintillation counting on the toluene phase. Examinations were made on the chemical yield and on the decontamination factor of the fission product nuclides. Analysis were made on the marine biological samples of Urazoko Bay, Fukui prefecture. Agreement of the radioactive cobalt data between that by the present method and that by Ge(Li) gamma ray spectometry was good. Also, the stable cobalt value by the present method agreed well with that by neutron activation analysis method.

Animals↗
PubMed1980

Tumor localization of radio-labeled antibodies against carcinoembryonic antigen in patients with carcinoma: a critical evaluation.

Purified, [131I]-labeled goat antibodies against carcinoembryonic antigen, which have been shown to localize in human carcinoma in nude mice, were injected into 27 patients with carcinoma. Patients were scanned with a scintillation camera at various intervals. In 11 patients, radioactivity was detectable in the tumor 48 hours after injection. Computerized subtraction of blood-pool radioactivity provided clearer pictures in positive cases, but in 16 patients the scans remained doubtful or negative. To study the specificity of [131I]-antibody localization, we gave some patients simultaneous injections of [125I]-labeled normal IgG. Both isotopes were measured by means of scintillation counting in tumors and normal tissues recovered after surgery. The results demonstrated that only the anti-CEA antibodies localized in tumors. However, the total antibody-derived radioactivity in the tumor was only about 0.001 of the injected dose. We conclude that, despite the present demonstration of specificity, this method of tumor detection is not yet clinically useful.

Aged↗
PubMed2004

An interface for direct analysis of (14)c in nonvolatile samples by accelerator mass spectrometry.

We describe here apparatus and methods for direct analysis of (14)C in biological specimens by accelerator mass spectrometry (AMS). Liquid samples, including plasma and urine, are deposited by pipet into a bed of CuO powder that fills a space within a rigid, refractory support. Volatile components are removed under reduced pressure prior to analysis. The CuO matrix is locally heated with an infrared laser while it is contained within a sealed chamber that is swept with He carrier gas. Heating induces combustion of the applied sample, and the carrier gas transports the CO(2) that is formed to the AMS instrument's ion source, which is appropriately modified for use with CO(2). A rodent study of drug clearance with [(14)C]-acetaminophen was performed to provide plasma and urine specimens, which were analyzed with this overall approach and by liquid scintillation counting for comparison. Results presented here confirm the potential utility of laser-induced sample combustion as an alternative to graphite production for AMS analysis of (14)C. Anticipated benefits of the present approach include reduced risk of sample cross-contamination, decreased analysis time, and greater compatibility with robotics.

Acetaminophen↗
PubMedDate not supplied

[The interorgan distribution of tritium-labelled para-aminobenzoic acid in the body of rats after its subcutaneous injection].

To study the pharmacokinetics of para-aminobenzoic acid (PABA), rats were subcutaneously injected with 3H-PABA (1 mkg/g body weight) at the stage (P7) when stimulation of outer segments of the photoreceptor cell morphogenesis is possible (Stroeva et al., 1990). The maximum labelling assayed for radioactivity by scintillation counting was observed in the liver 3 h after the injection while, in the blood the labelling was 3 times lower and, in the retina, one order lower than in the liver and blood. The label was detected in all the three types of tissue in 24 and 48 hours, being reduced by an order in comparison with each previous term of measurement. Biological structures binding 3H-PABA were not determined in the present study.

4-Aminobenzoic Acid↗
PubMed2005

Innovative procedure for the determination of gross-alpha/gross-beta activities in drinking water.

An alternative sample preparation method for the determination of gross-alpha/beta activity concentrations in drinking water is introduced in this paper. After the freeze-drying of tap water samples, determination by liquid scintillation counting can be applied utilizing alpha/beta separation. It has been shown that there is no adsorption or loss of solid radionuclides during the freeze-drying procedure. However, the samples have to be measured quickly after the preparation since the ingrowth of daughter isotopes negatively effects the measurement. The limits of detection for gross-alpha and gross-beta activity are in the range 25-210 mBq/l, respectively, for a measurement time of only 8-9 h.

Alpha Particles↗
PubMed1983

Autoradiographic and liquid scintillation assessment of beta-amino-propionitrile-induced inhibition of collagen maturation using 3H-proline and 3H-lysine.

BAPN (0.1 mg/day) was injected into chick embryos for 4 days starting on the 7th day of incubation. On the 11th day, the embryos were administered either 3H-proline or 3H-lysine. 36 h later, the incorporation of each isotope by the periosteal osteogenic cells as well as into bone matrix was investigated by autoradiography. The incorporation of the two isotopes into whole bones was assessed by liquid scintillation counting. 3H-proline incorporation into the cellular or matrical compartments was unaffected by treatment. As compared to the controls, 3H-lysine label in BAPN-treated embryonic bones was significantly higher in the cellular compartment but was reduced over the bone matrix. The data provide the first direct morphological evidence that BAPN probably induces certain changes in the maturation of collagen involving lysyl residues which result in an inhibition of cross-linkage formation in collagen.

Aminopropionitrile↗
PubMed2001

Determination of uranium isotopes in food and environmental samples by different techniques: a comparison.

The uranium concentration in 59 samples of bottled and tap water, mainly from northern Italy, was measured by different techniques. Results obtained by inductively coupled plasma mass spectrometry (ICP-MS), semiconductor alpha spectrometry and low level liquid scintillation counting with alpha/beta discrimination (LSC) have been compared. High resolution gamma spectrometry and semiconductor alpha spectrometry have been used to analyse uranium in a variety of organic and inorganic samples. Isotopic secular equilibrium in the 238U series may be lacking or hidden by auto-absorption phenomena, so caution should be used in evaluating gamma spectrometry data. Alpha spectrometry has also been used to ascertain the possible pollution from depleted uranium in the environment.

Food Contamination, Radioactive↗
PubMed1988

A sensitive radioenzymatic assay for epinephrine forming enzymes.

Epinephrine (E) is formed in the adrenal medulla by phenylethanolamine-N-methyltransferase (PNMT), and in other tissues. Enzymes other than PNMT may be able to synthesize E, but this has been difficult to investigate because most assays do not have E as their final product. This assay produces 3H-E from norepinephrine (NE) and 3H-S-adenosylmethionine. The 3H-E is isolated on alumina, 3H-S-adenosylmethionine is precipitated and the 3H-E is suspended in diethylhexyl phosphoric acid in toluene for scintillation counting. The assay is sensitive and linear over a wide range. E was formed by most tissues tested. Brain and adrenal contained an enzyme specific for NE, but cardiac ventricle contained an enzyme that methylated both NE and dopamine. Denervated tissues in adrenal medullectomized rats contained very little NE, but still had E and E forming enzyme present. This assay detects a non-neuronal E forming enzyme with activity in vitro and in vivo.

Adrenal Medulla↗
PubMed2003

[Radon-222 in drinking water of Karkonoskie Plateau].

Radon-222 concentration in surface water, wells water and tap water in the main towns and villages which are located in area of Karkonoskie Plateau has been quantitative determined. The measurements were performed using the alpha liquid scintillation counting method. Majority of waterworks in Karkonoskie Plateau is supplied with the ground water in which the radon concentration is high from 87.5 Bq/l to 818.1 Bq/l. The waterworks in Karpacz are supplied with the surface water, which main characteristic is low radon concentration (below 10 Bq/l) and with the ground water have a high radon concentration (to 541 Bq/l). Radon-222 concentration in water of individual wells was similar to concentration in the ground water.

Carcinogens, Environmental↗
PubMed2002

A method for the determination of enzyme mass loading on an electrode surface through radioisotope labelling.

A direct method has been developed for the quantitation of the amount of immobilised enzymes on biosensor surfaces. This quantity is of key importance in establishing the activity, kinetics and optimal immobilisation conditions in the construction of both amperometric and optical biosensors. Recombinant L-lactate dehydrogenase incorporating both a biosynthetically introduced radiolabel, 3H-leucine, and a hexahistidine peptide tag was immobilised on a poly(aniline) composite film and then quantitated by liquid scintillation counting. It was found that enzyme mass loading was proportional to the concentration of LDH in solution, and also depended on the morphology of the composite film. The LDH mass loading on the composite film doubled when a surface cysteine containing variant was used, possibly due to the covalent attachment of the cysteine to the diiminoquinoid rings of the poly(aniline).

Aniline Compounds↗
PubMed2004

The use of 96-well Scintiplates to facilitate definitive metabolism studies for drug candidates.

Semi-quantitative analysis of the drug-related components in biological samples collected during definitive metabolism studies using radiolabelled drug candidates is commonly achieved by HPLC profiling, using either on-line radiochemical detection or off-line liquid scintillation counting (LSC) following collection of the HPLC eluent into vials. However, although the use of LSC with vials has high sensitivity, the approach is time-consuming, laborious and destructive, whilst on-line detection methods are inappropriate for samples with low-levels of radioactivity (commonly the case with plasma samples). The use of 96-well microtitre plates (Scintiplates) for fraction collection during HPLC profiling provides a sensitive, effective and efficient alternative method for the semi-quantitative analysis of radiolabelled components in biological samples. Furthermore, the approach is non-destructive, such that subsequent identification of the isolated components can be achieved. Although the Scintiplate methodology is not appropriate for the analysis of excreta samples, where quenching of the radiochemical signal by endogenous components was observed, the approach was demonstrated to be valid for the relative quantification of [14C]-labelled material in plasma samples for all species investigated. In addition, good sensitivity was observed, with a counting efficiency of 79% for [14C], such that a drug-related component accounting for 10-15 dpm is quantifiable. The utility of the methodology for profiling circulating metabolites was demonstrated by the analysis of a rat plasma sample following oral administration of [14C]-UK-349,862. The Scintiplate approach and subsequent mass spectrometric analysis resulted in the relative quantitation and specific characterisation of circulating metabolites accounting for 93% of the total plasma radioactivity.

Animals↗
PubMed1998

A survey of 222Rn concentrations in domestic water supplies of Iran.

As part of a national program to determine public exposure to natural radiation, 222Rn concentrations were determined in domestic water supplies, including ground and surface waters, in 23 provincial centers using a liquid scintillation counting technique. The minimum and maximum mean concentrations of 222Rn in ground water were, respectively, 7.9+/-4.5 kBq m(-3) in Sanandaj and 46.5+/-11.5 kBq m(-3) in Tehran with an overall national mean value of 21+/-8.3 kBq m(-3). The 222Rn concentrations in surface waters ranged from less than 1 to 7 kBq m(-3) with a mean value of 3.9+/-1.9 kBq m(-3). The mean concentration of 222Rn in tap water in different parts of Tehran is 3.8+/-1.1 kBq m(-3). The results are presented and discussed in this paper.

Geography↗
PubMed1999

Development of a carbon dioxide-capture assay in microtiter plate for aspartyl-beta-hydroxylase.

CO2-capture methods have been used for assaying many decarboxylating enzymes including hydroxylation-coupled decarboxylation reactions. The traditional CO2-capture method involves performing the reaction in capped tubes and radiometric measurement of trapped 14CO2 by scintillation counting. In this report, a 14CO2-capture method in a 96-well microtiter plate format has been developed and a phosphor imaging system has been employed for sample measurement. The new assay method has been used successfully to assay aspartyl-beta-hydroxylase activity in microtiter plate format. The results obtained here compare favorably with those obtained from the traditional tube method. The method is sensitive, suitable for high throughput, and generally applicable to many CO2-releasing enzyme assays.

Carbon Dioxide↗
PubMed2006

Quality control of liquid scintillation counters.

Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220 Quantulus counter. The quality of the LSC measurements relies on the correct operation of these counters and their traceability to the frequency and time units.

Calibration↗
PubMed2001

Green tea and the metabolism of 2-amino-3-methylimidazo.

The effects of green tea intake on the metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the rat was studied. IQ belongs to a new class of mutagens and carcinogens, heterocyclic arylamines, formed during cooking through browning meats and fish, thus, in the food chain of most non-vegetarians. Ten adult male and female Fischer 344 rats were placed on a 2% solution of green tea and 10 control rats were on water for 6 weeks. Then, animals were administered a single dose of 40 mg/kg body weight of [2-14C]IQ by oral gavage. Twenty-four hour urine samples were collected and metabolites were separated by HPLC and quantitated by scintillation counting. Two minor and three major metabolites were isolated, including, small quantities of IQ itself. The rats on tea showed significant differences (P < 0.05) in the recovery of the three major metabolites, namely, IQ-sulfamate, IQ-5-O-sulfate, and IQ-5-O-glucuronide, respectively. Green tea, therefore, influences the manner in which the food carcinogen IQ is metabolized and excreted in urine. Formation of glucuronides, increased by green tea, represent a key means of detoxification of the heterocyclic amine, IQ.

Animals↗
PubMedDate not supplied

Distribution and elimination of hexachlorobenzene (HCB) after single oral exposure in Japanese quail (Coturnix coturnix japonica).

The distribution and excretion of hexachlorobenzene (HCB) after administration to quails of a single oral dose of 4.5 microCi [14C] HCB per 100 g body weight was studied by whole-body autoradiography and liquid scintillation counting. Radiolabeled HCB was distributed throughout the body in 2 h. Peak levels were found 4-8 d after administration, with the highest concentrations in the subcutaneous and abdominal fat, uropygial gland, bone marrow, adrenals, ovarian stroma, and liver, in that order. After 3 wk, substantial amounts of radiolabeled substance were present only in the adipose tissue and the uropygial gland. The main routes of excretion were the egg yolk, uropygial gland, and bile. About 75% of the administered dose was excreted through the egg yolk and about 25% in the feces.

Administration, Oral↗