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PubMed1981

Incorporation of radioactive free fatty acids into glycerolipids of subcellular fractions from human tonsil lymphocytes.

Human tonsil lymphocytes were cultured with phytohemagglutinin (PHA) for 1-72 hr. Throughout the culture periods studied, PHA stimulated similarly the synthesis of triacylglycerol, phosphatidylcholine and phosphatidylethanolamine from radioactive free fatty acids. There was no significant difference in the stimulation of cellular uptake of different labeled fatty acids tested (palmitic, stearic, oleic and arachidonic acids). Human tonsil lymphocytes were shown to be composed of heterogeneous cell populations with respect to the activities of cellular uptake of free fatty acids. The cells were subfractionated after being labeled with radioactive fatty acids for 6 hr. We found that the light and heavy plasma membranes, which are known to occur in human tonsil lymphocytes, are distinctly different from each other with respect to the labeling patterns of glycerolipids and also to the response to PHA. In the light plasma membranes, the labeling of phospholipids relative to that of triacylglycerol was much less than that of heavy plasma membranes and other organelles, though radioactivity of phosphatidylcholine per mg protein of light plasma membranes was the highest of any other organelles. Furthermore, the stimulation of phosphatidylcholine synthesis by PHA appeared most markedly in the light plasma membranes in comparison to other subcellular fractions.

Cells, Cultured↗

PubMed2001

Free radical-initiated and gap junction-mediated bystander effect due to nonuniform distribution of incorporated radioactivity in a three-dimensional tissue culture model.

To investigate the biological effects of nonuniform distribution of radioactivity in mammalian cells, we have developed a novel three-dimensional tissue culture model. Chinese hamster V79 cells were labeled with tritiated thymidine and mixed with unlabeled cells, and multicellular clusters (approximately 1.6 mm in diameter) were formed by gentle centrifugation. The short-range beta particles emitted by (3)H impart only self-irradiation of labeled cells without significant cross-irradiation of unlabeled bystander cells. The clusters were assembled in the absence or presence of 10% dimethyl sulfoxide (DMSO) and/or 100 microM lindane. DMSO is a hydroxyl radical scavenger, whereas lindane is an inhibitor of gap junctional intercellular communication. The clusters were maintained at 10.5 degrees C for 72 h to allow (3)H decays to accumulate and then dismantled, and the cells were plated for colony formation. When 100% of the cells were labeled, the surviving fraction was exponentially dependent on the mean level of radioactivity per labeled cell. A two-component exponential response was observed when either 50 or 10% of the cells were labeled. Though both DMSO and lindane significantly protected the unlabeled or bystander cells when 50 or 10% of the cells were labeled, the effect of lindane was greater than that of DMSO. In both cases, the combined treatment (DMSO + lindane) elicited maximum protection of the bystander cells. These results suggest that the bystander effects caused by nonuniform distributions of radioactivity are affected by the fraction of cells that are labeled. Furthermore, at least a part of these bystander effects are initiated by free radicals and are likely to be mediated by gap junctional intercellular communication.

Animals↗

PubMed2005

Modeling multicellular response to nonuniform distributions of radioactivity: differences in cellular response to self-dose and cross-dose.

Radiopharmaceuticals are distributed nonuniformly in tissue. While distributions of radioactivity often appear uniform at the organ level, in fact, microscopic examination reveals that only a fraction of the cells in tissue are labeled. Labeled cells and unlabeled cells often receive different absorbed doses depending on the extent of the nonuniformity and the characteristics of the emitted radiations. The labeled cells receive an absorbed dose from radioactivity within the cell (self-dose) as well as an absorbed dose from radioactivity in surrounding labeled cells (cross-dose). Unlabeled cells receive only a cross-dose. In recent communications, a multicellular cluster model was used to investigate the lethality of microscopic nonuniform distributions of 131I iododeoxyuridine (131IdU). For a given mean absorbed dose to the tissue, the dose response depended on the percentage of cells that were labeled. Specifically, when 1, 10 and 100% of the cells were labeled, a D37 of 6.4, 5.7 and 4.5 Gy, respectively, was observed. The reason for these differences was recently traced to differences in the cellular response to the self- and cross-doses delivered by 131IdU. Systematic isolation of the effects of self-dose resulted in a D37 of 1.2 +/- 0.3 Gy. The cross-dose component yielded a D37 of 6.4 +/- 0.5 Gy. In the present work, the overall survival of multicellular clusters containing 1, 10 and 100% labeled cells is modeled using a semi-empirical approach that uses the mean lethal self- and cross-doses and the fraction of cells labeled. There is excellent agreement between the theoretical model and the experimental data when the surviving fraction is greater than 1%. Therefore, when the distribution of 131I in tissue is nonuniform at the microscopic level, and the cellular response to self- and cross-doses differs, multicellular dosimetry can be used successfully to predict biological response, whereas the mean absorbed dose fails in this regard.

Animals↗

PubMed1976

Incorporation of radioactive precursors into the membrane and contents of the neurosecretory granules of the rat neurohypophysis as a method of studying their fate.

Rat neural lobes have been separated into subcellular fractions by differential centrifugation at various times after an intracisternal injection of [35S]cysteine or [3H]choline. Both isotopes led to a rise and fall in the radioactivity of neurosecretory granules (NSG) which paralleled that found previously for the neurohypophysial hormones and the neurophysins. While the radioactivity of the NSGs resulting from [35S]cysteine injection was predominantly associated with granular contents, [3H]choline injections led to a preferential labelling of the granular membrane. There was no indication of a sequential movement of radioactivity from the NSG-membrane fraction into the microsomal fraction (containing the so-called small vesicles) which might be expected if granular membrane were recaptured as small vesicles after release of secretory product by exocytosis. When release was stimulated in injected animals by giving them 2% NaCl solution to drink, 35S diappeared from the gland as expected, but 3H was retained and, moreover, appeared in the NSG-membrane fraction; results compatible with membrane conservation occurring by recapture of large vesicles. There was an indication that some of the neurophysin in the NSG was membrane-bound and that this too was retained after release of the granular contents.

Animals↗

PubMed1978

Disappearance of the difference between adrenal A and NA cells in the level of radioactivity after 3H-dopa injection in the hypophysectomized mouse.

Radioactivity in adrenal medullary chromaffin cells of the mouse was examined by autoradiographic methods 15 min to 1 hr after an intraperitoneal injection of 3H-dopa. In the normal control mice, the concentration of radioactivity was significantly higher in the A cells than in the NA cells, whereas in the hypophysectomized mice (9 days after operation by the transauricular method) the radioactivity was evenly distributed in the two cell types. It was suggested that both A and NA cells possessed a special trapping and concentrating mechanism for extracellular dopa and/or its metabolites and that the activity of this mechanism was made greater in the A cells than in the NA cells by the pituitary gland.

Adrenal Medulla↗

PubMed2006

Development and optimization of a non-radioactive JNK3 assay.

In light of emerging interest in the relevance of c-Jun NH2-terminal protein kinase 3 (JNK3) as a promising drug target, we describe here an advanced non-radioactive immunosorbent JNK3 activity assay that is applicable for routine screening of small molecule ATP-competitive enzyme inhibitors. We modified and established a JNK3/ATF-2 protocol based on our previously described p38 MAPK method [1] for a substrate-bound non-radioactive procedure that represents a convenient alternative to conventional radioactive protein kinase assays. The objective of the present study was to validate these conditions by using the reference compounds SP600125 and SB203580 to achieve comparable IC(50) results to published data. Furthermore, an IC(50) for staurosporine was determined. The protocol we describe here represents an accessible and robust screening assay for JNK3 inhibitors.

Adenosine Triphosphate↗

PubMed2003

The management of hyperthyroidism in children with emphasis on the use of radioactive iodine.

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long-term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Because of the theoretical risk of thyroid cancer after thyroid irradiation in individuals less than 20 years of age, relatively high doses of radioactive iodine should be administered to minimize residual thyroid tissue.

Child↗

PubMed2001

The use of radioactive iodine in the management of hyperthyroidism in children.

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Because of the theoretical risk of thyroid cancer after thyroid irradiation in individuals less than 20 years of age, relatively high doses of radioactive iodine should be administered to minimize the persistence of residual thyroid tissue.

Antithyroid Agents↗

PubMed1996

CT findings after laparoscopic pelvic lymph node dissection and transperineal radioactive seed implantation for prostatic carcinoma.

OBJECTIVE: The purpose of this paper is to describe the CT findings in patients undergoing transperineal sonographically guided radioactive seed implantation with and without laparoscopic lymph node dissection for treatment of carcinoma of the prostate gland. MATERIALS AND METHODS: Ninety-six CT scans of the pelvis were retrospectively reviewed in patients who had undergone radioactive seed implantation of the prostate gland. The CT readings were correlated with the type of procedure each patient had and the pathologic results of laparoscopic lymph node dissection. RESULTS: Of 73 patients who underwent laparoscopic lymph node dissection, 42 were found at CT to have low-attenuation masses along lymph node chains. These masses resembled necrotic nodes. Only one patient who did not undergo laparoscopic lymph node dissection had similar findings. Fourteen patients had fluid collections within the pelvis, 13 of whom had undergone laparoscopic lymph node dissection. Other imaging findings included ectopic seeds (10 patients) and subcutaneous and intrapelvic air (11 patients). All except two patients had negative pathology reports for the removed lymph nodes. CONCLUSION: A wide variety of imaging findings may be seen after radioactive seed implantation and laparoscopic lymph node dissection, including masses that resemble necrotic lymph nodes. Radiologists should be aware of these findings in asymptomatic patients.

Brachytherapy↗

PubMed1998

Total radioactive residues and clenbuterol residues in edible tissues, and the stereochemical composition of clenbuterol in livers of broilers after exposure to three levels of dietary [14C]clenbuterol HCl and three preslaughter withdrawal periods.

Thirty-six broiler chickens were randomly assigned to .5, 1.0, or 2.0 ppm dietary [14C]clenbuterol HCl for a 2-wk period starting at 5 wk of age. Four birds from each treatment were slaughtered after withdrawal periods of 0, 7, or 14 d. Total radioactive residues (TRR; clenbuterol HCl equivalents) were measured in adipose tissue, kidney, liver, skin with adhering adipose tissue, bile, blood, brain, gastrointestinal tract, heart, lung, spleen, and testes; parent clenbuterol was measured in liver and kidney. In edible tissues, TRR were roughly proportional to dietary [14C]clenbuterol level and inversely proportional to duration of the withdrawal period; kidney TRR ranged from nondetectable (14 d of withdrawal, .5 and 1.0 ppm treatments) to 211.5 ppb for the 2.0 ppm treatment at zero withdrawal. Liver TRR were detectable for all treatment and withdrawal periods. Rapid depletion of TRR from edible tissues occurred during the first 7 d of the withdrawal period, but depletion of TRR was much slower thereafter. Parent clenbuterol was below the limit of detection (1 ppb) or was undetectable in liver and kidney for all dietary levels after 7 and 14 d of withdrawal, but it represented 22 to 48% of the total radioactive residues at 0 withdrawal. The inactive S (+) stereoisomer constituted approximately 73% of the total clenbuterol residue in livers of chickens slaughtered with no withdrawal period, and the active R (-) stereoisomer accounted for the remainder. These data indicate that radioactive residues of clenbuterol were present well after parent clenbuterol had depleted from edible tissues in chickens, and the predominant stereoisomer remaining in livers at slaughter was the inactive isomer.

Adipose Tissue↗

PubMedDate not supplied

Radioactive labeling of phospholipids and proteins by cochlear perfusion in the guinea pig and the effect of neomycin.

Phospholipids and proteins of guinea pig stria vascularis, spiral ligament and organ of Corti were radioactively labeled by perilymphatic perfusion with artificial perilymph containing [32P] orthophosphate or radioactive amino acids. Phospholipids were separated by thin-layer chromatography, proteins by disc gel electrophoresis and quantitated by liquid scintillation counting. The addition of 10-4M to 10-2M neomycin to the perfusion fluid resulted in a dose-dependent increase of tissue permeability to the radioactive precursors, and a specific decrease in the 32P-incorporation into phosphatidylinositol diphosphate in stria vascularis and organ of Corti. No effect of neomycin on protein labeling was observed using a double label approach with [3H]methionine and [35S]-methionine. In vitro, low concentrations of neomycin led to the formation of a complex and polyphosphoinositides. Much higher concentrations of the drug were needed for a comparable reaction with the acid mucopolysaccharide, chondroitin sulfate A. The implications of these findings for the mechanism of neomycin ototoxicity are discussed.

Animals↗

PubMed1987

Incorporation of radioactivity into amino acids and fatty acids after administration of 14C-geranylgeranylacetone to rats.

The radioactive components present in plasma proteins and adipose tissue after oral dosing of 14C-geranylgeranylacetone (GGA) to rats were characterized by gel filtration, paper electrophoresis, t.l.c. and reversed-phase column chromatography. The radioactivity associated with the plasma proteins was identified as 14C-labelled amino acids (Glu, Asp, Ala, Pro, Gly and probably Ser); however, no 14C was detectable in the essential amino acids. Radioactivity accumulated in adipose tissue as 14C-labelled fatty acids of triglycerides. The incorporation of 14C into amino acids and fatty acids may be due to the formation of 14C-propionyl-CoA resulting from omega-oxidation and successive beta-oxidations of 14C-GGA. This view was supported by the finding that 14C-acetate was incorporated into amino acids and fatty acids in a similar manner to 14C-GGA.

Acetates↗

PubMed1975

Effects of protein deficiency on the rate of radioactivity loss from body constituents in adult rats given 14C-amino acids.

The effect of protein deficiency on the rate of loss of radioactivity from body constituents was studied in adult rats administered 14C-Chlorella protein hydrolysate or 14C-lysine. Rats were kept on a protein-free diet for 3 weeks and then injected with labelled amino acids and fed on a protein-free diet for 3 more days to allow 14C deposition in tissues. Then they were given experimental diets (protein-free diet, 1% and 10% wheat gluten diets pair-fed with the protein-free diet, and 10% wheat gluten diet ad libitum) for 7 days and sacrificed. The rates of loss of radioactivity from tissue proteins became low in general with the extent of protein deficiency. This increased capacity of tissues to retain 14C-amino acids may result from higher efficiency of protein utilization in protein deficiency. The reutilization of free amino acids and the rate of catabolism of tissue proteins are discussed on the basis of the results. The half-life of muscle protein was too long to observe the effects of experimental diets given for 7 days on the rate of loss of radioactivity.

Amino Acids↗

PubMed1979

Effect of Eimeria species on the appearance of radioactivity in the blood of chicks fed radio-labeled glucose or 3-0-methyl-D-glucose.

Results of five trials with four species of coccidia (Eimeria acervulina, E. necatrix, E. tenella, and E. brunetti) failed to demonstrate any interference with glucose absorption in the parasitized intestines of intact chick hosts. In addition, circulating blood radioactivity in severely parasitized chicks, as evidenced by weight gain data and intestinal lesion scores, was significantly higher than that in control chicks following oral administration of 14C-glucose or 3-0-methyl-D-14C-glucose at 6 days postinfection. During the recovery phase of the infection (14 to 21 days postinfection), severely infected chicks rapidly gained weight and the blood radioactivity of parasitized chicks was consistently higher than that of uninfected control chicks. No significant differences in weight or blood radioactivity were observed during the post-recovery period (28 to 35 days postinfection).

Animals↗

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↗

PubMed1984

[Studies on background radioactivity in the Niigata City area--identification of natural nuclides present in underground (well) water samples].

Background radioactivity levels in Niigata city area were studied through the years of 1981-1984. As the results, it was found that the gross beta-radioactivity in underground (well) water samples were comparatively higher than those of other ground water samples. Ion chromatographic and gamma-ray spectroscopic determination revealed that this higher radioactivities were contributed by 40K rather than radium or thorium series nuclides or fallout originated 90Sr.

Background Radiation↗

PubMed1986

[High-yield synthesis of 14C labeled alicyclic amino acids with high specific radioactivity using potassium (14C) cyanide].

In order to study the tumor specificity of synthetic nonmetabolizing amino acids, 10 different 14C labeled alicyclic amino acids (3a-3j) were synthesized in high yield and with high specific radioactivity. Carbon-14 labeled alicyclic hydantoins (2a-2j) were synthesized from a small amount of radioactive potassium [14C] cyanide and corresponding ketones (1a-1j). Th 14C hydantoins (2a-2j) thus obtained were hydrolyzed without isolation to give 14C labeled alicyclic amino acids (3a-3j). The overall radiochemical yields of the amino acids (3a-3j) from potassium [14C] cyanide were 55.6-93.2% with radiochemical purity more than 99%. Specific activities of these 14C labeled compounds (3a-3j) were 209- 250 MBq/mmol (5.66-6.75 mCi/mmol). When non-radioactive potassium cyanide was not added as a carrier, 1-aminocyclopentane[14C]-carboxylic acid (3b) and 1-aminocyclooctane[14C]carboxylic acid (3e) were synthesized in the yield of 64.9 and 19.0% respectively with the specific activity exceed more than 1.85 GBq/mmol (50mCi/mmol).

Amino Acids↗

PubMed1995

Non-radioactive mismatch analysis to detect small mutations in human hypoxanthine-guanine phosphoribosyl transferase cDNA.

We have combined a cDNA-driven PCR technique and a non-radioactive chemical-cleavage mismatch method, followed by a direct sequencing for detecting small mutations in the human hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene. HPRT cDNA was synthesized by RT-PCR from 1,000 wild-type or HPRT(-) mutant cells. Wild-type cDNA was hybridized with mutant cDNA to form heteroduplexes. The resultant mismatched bases were modified and cleaved by base-specific chemicals, followed by analysis by denaturing polyacrylamide gel electrophoresis. Cleaved fragments were detected without using radioactive materials. Finally, direct sequencing of the PCR products was performed with a focus on a small limited region indicated by the mismatch analysis (focused sequencing). In this study, three small mutations in exon-3 of HPRT cDNA were detected and characterized completely with this system. As compared with the radioactive method, this system was shown to be very simple and efficient.

Base Sequence↗