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PubMed1984

Cytogenetic effects of cyclamates.

PHA-stimulated human peripheral lymphocytes were used as a model system for assessing the in vitro effects of calcium cyclamate. Techniques of autoradiography, cytological staining, cell counting, liquid scintillation and karyotyping were used to study the cytogenetic damage and biochemical effects of calcium cyclamate when assayed in 24 hour intervals for 96 hours. The cells were exposed to 10(-2) and 10(-3) molar concentrations of calcium cyclamate in TC 199 medium with fetal calf serum and antibiotics. These studies were carried out in three (3) phases. Phase I was primarily orientation studies of the effects of cyclamates and included running preliminary test checks, the establishment of parameters of dosage, assessing growth patterns and selecting key chromosomal aberrations. Sixty four (64) of the metaphase spreads showed morphologically detectable changes and aberrations. It was also noted that the addition of cyclamate increased mitotic rate of lymphocyte cells in cultures. Phase III arranged research designs to determine more precise characterization of chromosomal observations and morphological effects. Among other findings it was noted that of 13 types of observations only ten were found in the experimental group. The introduction of cyclamates increased the stability of the leucocyte cultures. These studies reinforced the findings on the increase of mitotic rate. Phase III extended protocols to include autoradiography and scintillation counting. It was determined that calcium cyclamate impaired the synthesis of deoxribonunucleic acid (as depicted by decreased incorporation of tritiated thymidine), reduced grain counts in autoradiographs and increased chromosome aberrations in cyclamate treated PHA stimulated peripheral blood lymphocytes in vitro. Morphological changes and growth rates showed significant effects. These studies indicate that calcium cyclamate has variable significant effects on leucocytes growth and chromosome morphology.

Autoradiography↗
PubMed1987

Sulfation of minoxidil by human platelet sulfotransferase.

In an attempt to determine whether (1) sulfotransferase activity in human platelets would convert minoxidil to minoxidil sulfate and (2) inter-subject variations in this sulfotransferase activity could be noted, platelet homogenates were incubated with minoxidil and 35S-PAPS in HEPES buffer at 37 degrees C for 30 min. Radioactivity which was extracted into ethyl acetate and shown by HPLC to elute with authentic minoxidil sulfate was counted by scintillation counting. Aliquots of the platelet homogenates were also preincubated at 43 degrees C for 15 min to determine the thermal stability of the sulfotransferase activity. Sulfotransferase activity in platelets from 48 adult males ranged from 0.9-13.2 pmol minoxidil sulfate produced/10(7) platelets per 30 min (mean 4.91 +/- 2.84 pmol/10(7) platelets per 30 min +/- SD). Thermal stable sulfotransferase activity ranged from 0.2-7.6 pmol minoxidil produced/10(7) platelets per 30 min and varied from 15 to 57% of the total sulfotransferase activity. Thus, the results indicate that human platelets can effect the sulfation of minoxidil and that sulfotransferase activity does show inter-subject variation.

Adolescent↗
PubMed1989

In vitro thymidine uptake and incorporation into thymic and bursal lymphocytes from young hypothyroidic chickens.

Experiments were conducted to evaluate the ability of thymic and bursal lymphocytes from hypothyroidic chicks to take up 3H-thymidine. To produce hypothyroidism, chicks were fed a diet containing thiouracil (0.1%) from day of hatch to 3 weeks of age. At 1, 2 and 3 weeks of age, body weights were significantly lower for hypothyroid chicks, and at 2 and 3 weeks of age, the relative weights of the thymus and bursa were significantly less than those of controls. Furthermore, chicks treated with thiouracil had significantly lower serum concentrations of 3,5,3'-triiodothyronine (T3) and thyroxine (T4). Thymic cells from hypothyroid chicks incorporated less 3H-thymidine at 1 and 3 weeks of age as assessed by liquid scintillation counting and autoradiography. Liquid scintillation counts for labeled bursal cells from hypothyroid chicks were not lower at 1 week of age, but the counts were lower at 3 weeks of age. Autoradiographic studies with bursal cells revealed that 3H-thymidine incorporation was less, but not significantly less, in medium-size lymphocytes from thiouracil-treated chicks at both 1 and 3 weeks of age. Thymidine incorporation into large bursal cells was affected more by thiouracil treatment at 1 than 3 weeks of age.

Animals↗
PubMed2003

[The effects of traditional Chinese medicines on the adherence of Streptococcus mutans to salivary acquired pellicle in vitro].

OBJECTIVES: To investigate the effects of traditional Chinese medicines on the preliminary adherence of Streptococcus mutans to salivary acquired pellicles. METHODS: The hydroxyapatites beads were coated by saliva to form S-HA, an in vitro model of experimental pellicle. Streptococcus mutans was chosen as the experiment strain, and radiolabeled with 3H-thymidine. Two parts of adherence inhibit study were carried on with medicines pretreated S-HA and medicines pretreated bacteria. The numbers of 3H-thymidine labeled bacteria attached to S-HA were counted by scintillation counting to indicate the amount of adherence. RESULTS: It was found that most of the traditional Chinese medicines tested could inhibit the adherence to S-HA to different extent, especially the Galla Chinensis, which has significant inhibitory action. CONCLUSION: Galla Chinensis may be a prospective medicine to inhibit the cariogenic bacteria's preliminary adherence to salivary acquired pellicles.

Bacterial Adhesion↗
PubMed1996

Development of a quantitative polyacrylamide gel electrophoresis analysis using a multichannel radioactivity counter for the evaluation of oligonucleotide-bound drug carrier.

A quantitative polyacrylamide gel electrophoresis (PAGE) analysis using a multichannel radioactivity counter was designed for the evaluation of 33P-labeled antisense oligonucleotide associated with polymeric drug carrier (nanoparticles). The proposed analytical method was first validated. The criteria of specificity, linearity, reliability, detection and quantification limits, and resolution power were determined. Results were compared to those obtained using liquid scintillation counting of crude samples or after solubilization of gel slices. The proposed method gave a better linearity and reliability than liquid scintillation counting of solubilized gel slices. In comparison with the liquid scintillation counting of crude samples, the method presented the advantage of being able to directly separate oligonucleotides differing by only one nucleotide in length. This method was applied for the separation of free oligonucleotides and oligonucleotides bound onto nanoparticles, allowing quantification of the amount of free and bound oligonucleotides without any further separation steps. Thus, because it is easy and rapid, the quantitative PAGE analysis using a multichannel radioactivity counter offers interesting possibilities for the characterization of oligonucleotide nanoparticles.

Cyanoacrylates↗
PubMedDate not supplied

Enhanced bacterial adhesion on surfaces pretreated with fibrinogen and fibronectin.

The effect of certain plasma proteins on the adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis on polyurethane, polyvinylchloride, or glass was investigated. Test surfaces were treated with serum, plasma, albumin, immunoglobulin G, fibrinogen, or fibronectin. Using a specially designed test chamber, surfaces previously treated with test proteins were incubated with bacterial suspension. During the experiment, the test chamber was placed on a rotator to prevent settling of bacteria. At the end of the experiment, each test well was rinsed repeatedly to remove non-adherent bacteria. The number of bacteria adherent to the test surfaces was quantitated by a combination of methods including microscopic counting of cells, scintillation counting and autoradiography. It was noted that a greater number of bacteria adhered to surfaces coated with fibrinogen or fibronectin whereas surfaces treated with serum showed reduced bacterial adhesion. The inhibitory effect of serum appeared more pronounced with S. epidermidis when compared with P. aeruginosa under identical experimental conditions. Scanning electron microscopy revealed that adherent bacteria were randomly distributed on the test surfaces and appeared to replicate while still adherent. These observations suggested that bacterial adhesion to biomaterials can be significantly influenced by the composition of the adsorbed proteins at the interface.

Adsorption↗
PubMed2006

Absolute activity measurement of the electron-capture-based radionuclides 139Ce, 125I, 192Ir and 65Zn by liquid scintillation coincidence counting.

Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. 125I, 192Ir and 65Zn were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The 139Ce measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since 139Ce decays purely by electron-capture, the basic method is described for this radionuclide. Results and difficulties encountered are discussed and uncertainty budgets are presented.

Algorithms↗
PubMed1995

Activation markers and cell proliferation as indicators of toxicity: a flow cytometric approach.

Cell proliferation is an attractive endpoint in in vitro toxicity assays, since nearly any kind of damage in a cell may result in altered cell proliferation. In toxicological applications, liquid scintillation counting, measuring radioactivity from tritiated thymidine, has been the traditional way to estimate cell proliferation. An alternative approach is the measurement of BrdU incorporation by flow cytometry. Before the actual DNA synthesis starts, several proteins are expressed on the cell surface, as well as intracellularly. Among the markers on the cell surface CD69, CD25, and CD71 are sequentially expressed on human lymphocytes after a mitogenic stimulation. The aim of this study was to evaluate information obtained by analysis of expression of activation markers on cell surfaces in lymphocyte subsets and to compare it with data from cell proliferation studies performed by liquid scintillation counting and BrdU flow cytometry. The experiments were performed with phytohemagglutinin-stimulated human lymphocytes exposed to ochratoxin A and cyclosporin A. While ochratoxin A-treated cultures showed a steep inhibition with increasing concentration, the cyclosporin A treatment gave an inhibition curve with a less steep slope. Activation marker studies showed that the effect of treatment with both of the toxins was more pronounced on the late markers CD25 and CD71, while CD69 had the advantage that significant effects could be detected as early as 6 h after ochratoxin A treatment. Cyclosporin A treatment induced only minor alterations in CD69 expression. Certain differences in expression of activation markers between CD4+ and CD8+ subsets were found both in ochratoxin A- and cyclosporin A-treated cultures. A stimulating effect was found in cell cultures exposed to the lowest concentration of ochratoxin A on CD69 and CD25 expression. Signs of an increase in frequencies of proliferating cells measured with the BrdU flow cytometry method were also seen. This increase could not be detected with liquid scintillation counting. No other differences between the liquid scintillation counting and BrdU flow cytometry measurements of proliferation were obtained. We conclude that studies of activation marker expression by the flow cytometric approach used in this report are useful complements to traditional measurements of cell proliferation as they yield subset-specific information about cellular processes which precede proliferation of lymphocytes.

Adult↗
PubMedDate not supplied

Evaluation of thrombogenicity by indium-111 platelet scintigraphy in endografting for abdominal aortic aneurysms.

Obstruction of the endograft limb by thrombosis has often been reported and may cause fatal complications such as leg necrosis or myonephropathic metabolic syndrome. The purpose of this study was to evaluate endograft antithrombogenicity by indium-111 platelet scintigraphy. Seventeen patients with abdominal aortic aneurysms were treated by endografting. Thirteen patients were treated with conventional open surgery using an artificial graft. The endograft was constructed from a self-expanding Z-shaped stent and woven polyester fabric. Autologous platelets labeled with indium-111 were injected at 2 weeks postoperatively. At 24 hours and 72 hours postinjection, the ratio of scintillation count of the endograft or graft to that of the native artery was calculated to assess platelet deposition. The normalization ratio was calculated as follows: (scintillation count per pixel of endograft or graft/circumference)/(scintillation count per pixel of the native femoral artery). Platelet factor 4 and beta-thromboglobulin were measured to evaluate the systemic platelets activity at 2 weeks postoperatively. There was no significant difference in platelet counts or labeling efficiency between the groups. The ratio was significantly higher in the endografting group than in the open surgery group at 72 hours postinjection (2.5-0.7 vs 3.9-1.1, P<.001). There was no significant difference in platelet factor 4 and beta-thromboglobulin between the groups. Although there was no difference in systemic platelet activity, endografting was associated with lower antithrombogenicity. It remains unclear whether lower antithrombogenicity causes thromboembolism as a complication of the procedure. The authors recommend the administration of antiplatelet drugs to prevent endograft obstruction in patients with very narrow iliac arteries.

Aged↗
PubMedDate not supplied

[In vitro incorporation of tritiated thymidine in acute leukemia and response to chemotheraphy (author's transl)].

The incorporation of tritiated thymidine (3H-TdR) has been assessed in 52 cases of adult acute leukemia, during the first phase of the disease, before and after 48 hours of chemotherapy. Two methods were utilized simultaneously: the measurement of the incorporation of 3H-TdR by liquid scintillation counting and the labeling index by autoradiography. These two data allowed to appreciate the mean incorporation per labeled blast cell. A significant correlation has been found between liquid scintillation counting and labeling index on the one hand, between mean incorporation per labeled blast cell and mean grain count on the other hand. The prognostic value of these different data was significant, at least if one consider the chance to get a complemente remission with the various drugs which were utilized. The responders are characterized, on the average, by a high rate of incorporation of 3H-TdR before therapy, with a higher labeling index than the non-responders. The measurement of the variations of incorporation of 3H-TdR, 48 hours after starting chemotherapy and before any morphological change, allows an early evaluation of the therapeutic effect: in the responders there is generally a decrease of the 3H-TdR incorporation and of the labeling index. On the apposite in the non-responders there is an increase of the mean incorporation per labeled blast cell, even if the labeling index decreases. The measurement of the incorporation of 3H-TdR by liquid scintillation counting which gives an earlier response than autoradiography, may be considered as a useful prognostic tool in acute leukemia, mainly in the non-lymphoblastic types and during the first phase of the disease.

Acute Disease↗
PubMed1994

Distribution of carbon-14 and associated radiation dose in rat fetal brain and liver after maternal injection of [14C]thymidine.

Pregnant Sprague-Dawley rats were injected intravenously with [14C]thymidine on day 13.5 of gestation, and the concentrations and radiation doses of 14C in the fetal brain and liver were determined by liquid scintillation counting and autoradiography with imaging plates. The concentrations of 14C in the whole fetal brains determined by liquid scintillation counting were 1.01% of the injected dose per gram wet weight at 6 h after injection and decreased to 0.39% g-1 at 48 h after injection. A significant accumulation of 14C was observed in the fetal liver: 3.8 and 0.51% of the injected dose per gram wet weight at 6 and 48 h after injection, respectively. Autoradiography showed that, especially at earlier periods after injection, there was remarkable concentration of 14C in the ventricular zone of the brain and the central region of the liver. With increasing time after injection, the distribution of 14C became relatively uniform. The concentrations of 14C in the ventricular zone of the fetal brain, determined by autoradiography, were much higher than those in the whole brain as determined by liquid scintillation counting. Cumulative radiation doses for 6-48 h after injection were 1.27 mGy for the whole fetus and 1.45 mGy for the whole brain. In contrast, the cumulative radiation dose for the ventricular zone of the brain which was determined by autoradiography was approximately 2.2 times that for the whole brain.

Animals↗
PubMed1991

Solid scintillators for receptor assays: an environmentally safe alternative to liquid scintillation cocktails.

Scintillation counting of tritiated ligands is widespread in receptor assays and has necessitated the use of scintillation cocktails containing environmentally damaging solvents that pose health hazards to their users. A safer mode of dry scintillation counting, based on the solid scintillator Xtalscint, was evaluated in whole-cell and membrane receptor assays. The results compared favorably with those obtained with glass-fiber filters and conventional liquid counting methods. It is concluded that solid scintillators may be used as an environmentally safer alternative to liquid scintillation in these assays.

Absorption↗
PubMed2000

Metabolism and excretion of [(14)C]celecoxib in healthy male volunteers.

We determined the disposition of a single 300-mg dose of [(14)C]celecoxib in eight healthy male subjects. The [(14)C]celecoxib was administered as a fine suspension reconstituted in 80 ml of an apple juice/Tween 80/ethanol mixture. Blood and saliva samples were collected at selected time intervals after dosing. All urine and feces were collected on the 10 consecutive days after dose administration. Radioactivity in each sample was determined by liquid scintillation counting or complete oxidation and liquid scintillation counting. Metabolic profiles in plasma, urine, and feces were obtained by HPLC, and metabolites were identified by mass spectrometry and NMR. [(14)C]Celecoxib was well absorbed, reaching peak plasma concentrations within 2 h of dosing. [(14)C]Celecoxib was extensively metabolized, with only 2.56% of the radioactive dose excreted as celecoxib in either urine or feces. The total percentage of administered radioactive dose recovered was 84.8 +/- 4.9%, with 27.1 +/- 2.2% in the urine and 57.6 +/- 7.3% in the feces. The oxidative metabolism of celecoxib involved hydroxylation of celecoxib at the methyl moiety followed by further oxidation of the hydroxyl group to form a carboxylic acid metabolite. The carboxylic acid metabolite of celecoxib was conjugated with glucuronide to form the 1-O-glucuronide. The percentages of the dose excreted in the feces as celecoxib and the carboxylic acid metabolite were 2.56 +/- 1.09 and 54.4 +/- 6.8%, respectively. The majority of the dose excreted in the urine was the carboxylic acid metabolite (18.8 +/- 2.1%); only a small amount was excreted as the acyl glucuronide (1.48 +/- 0.15%).

Administration, Oral↗
PubMed2000

Lymphoscintigraphy and ultrasound-guided fine needle aspiration cytology of sentinel lymph nodes in head and neck cancer patients.

Accurate staging of the regional lymph nodes is crucial for the appropriate management of patients with squamous cell carcinoma of the head and neck (HNSCC). However, the current diagnostic modalities have low accuracy for N0 neck, and even the most optimal procedure, ultrasound-guided fine needle aspiration cytology (USgFNAC), still has a sensitivity of only 42%-73%. In this study we evaluated whether the identification of the sentinel node might improve the selection of lymph nodes for USgFNAC. Twelve HNSCC patients received 3-4 peritumoral injections of 10-30 MBq 99mTc-labeled colloidal albumin, and the sentinel node was identified by dynamic scintigraphy and marked on the skin using a handheld probe, and/or by scintillation counting of the aspirates. After sentinel node identification USgFNAC was performed. Correct aspiration of the identified sentinel node(s) was confirmed by scintillation counting. In 11 out of 12 cases the sentinel node(s) could be visualized by dynamic planar imaging. In one case the sentinel node(s) were identified by scintillation counting only. In a number of patients different or supplementary lymph nodes were aspirated on the basis of sentinel node identification. These initial data strongly suggest that sentinel node identification might improve the staging of the neck by USgFNAC.

Biopsy, Needle↗
PubMed1997

Detecting strontium-89 removable contamination using a sodium iodide well counter.

UNLABELLED: Monitoring for 89Sr removable contamination is required for incoming DOT-labeled packages and work areas containing radioactivity. However, few nuclear medicine departments are equipped for liquid scintillation counting, which is the preferred method for detecting beta emitters. We investigated using a sodium iodide well counter to detect 89Sr through its bremsstrahlung photon production. METHODS: We used a manufacturer's 89Sr-chloride solution of known concentration and tested various parameters: type of tube, access of tube contents to air, volume of sample, type of wipe material and counting geometry. Liquid scintillation samples also were obtained. RESULTS: Initial counting efficiencies were 0.10-0.14 cpm/dpm for small volume (10-microliter) samples. The various parameters tested had either positive or negative effects on the system's efficiency to detect 89Sr. One set of samples, counted over time, demonstrated a calculated mean half-life of 50.8 days, which is similar to the 89Sr reported half-life of 50.5 days. Liquid scintillation samples demonstrated efficiencies of almost 1.0 cpm/dpm and a calculated mean half-life of 50.8 days, both as expected. CONCLUSION: This study demonstrates that 89Sr removable contamination can be detected sensitively using a sodium iodide well counter, but special considerations must be made when determining the system's counting efficiency.

Air Pollutants, Radioactive↗