Radiolabelling of α-bungarotoxin to high specific radioactivity with complete retention of biological activity

1984 ◽  
Vol 12 (5) ◽  
pp. 813-814 ◽  
Author(s):  
THOMAS BARKAS ◽  
BERNARD W. FULPIUS
Keyword(s):  
Biological Activity ◽  
Specific Radioactivity ◽  
High Specific Radioactivity

scholarly journals 125I-Labelling of Erythropoietin without Loss of Biological Activity

1976 ◽  
Vol 159 (2) ◽  
pp. 287-292 ◽  
Author(s):  
M J Murphy
Keyword(s):  
Biological Activity ◽  
Glucose Oxidase ◽  
Catalytic Properties ◽  
Specific Radioactivity ◽  
Biological Integrity ◽  
High Specific Radioactivity

Erythropoietin, the hormone that regulates erythropoiesis in mammals, was 125I-labelled by using the catalytic properties of lactoperoxidase and the H2O2-generating properties of glucose oxidase. This methodology, both rapid and simple, not only produced hormone preparations with high specific radioactivity but also did not substantially alter the biological integrity of erythropoietin when it was assayed in vivo.

Synthesis of high-specific-radioactivity 4- and 6-[18F]fluorometaraminol- PET tracers for the adrenergic nervous system of the heart

2001 ◽  
Vol 9 (3) ◽  
pp. 677-694 ◽  
Author(s):  
Oliver Langer ◽  
Frédéric Dollé ◽  
Héric Valette ◽  
Christer Halldin ◽  
Françoise Vaufrey ◽  
...  
Keyword(s):  
Nervous System ◽  
Specific Radioactivity ◽  
Pet Tracers ◽  
High Specific Radioactivity ◽  
Adrenergic Nervous System

scholarly journals Interactions of Nereistoxin and Its Analogs with Vertebrate Nicotinic Acetylcholine Receptors and Molluscan ACh Binding Proteins

Marine Drugs ◽  
2022 ◽  
Vol 20 (1) ◽  
pp. 49
Author(s):  
William Kem ◽  
Kristin Andrud ◽  
Galen Bruno ◽  
Hong Xing ◽  
Ferenc Soti ◽  
...  
Keyword(s):  
Disulfide Bond ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Specific Radioactivity ◽  
Electric Organ ◽  
Binding Affinities ◽  
Nicotinic Acetylcholine ◽  
High Affinity ◽  
High Specific Radioactivity ◽  
Alpha Bungarotoxin

Nereistoxin (NTX) is a marine toxin isolated from an annelid worm that lives along the coasts of Japan. Its insecticidal properties were discovered decades ago and this stimulated the development of a variety of insecticides such as Cartap that are readily transformed into NTX. One unusual feature of NTX is that it is a small cyclic molecule that contains a disulfide bond. In spite of its size, it acts as an antagonist at insect and mammalian nicotinic acetylcholine receptors (nAChRs). The functional importance of the disulfide bond was assessed by determining the effects of inserting a methylene group between the two sulfur atoms, creating dimethylaminodithiane (DMA-DT). We also assessed the effect of methylating the NTX and DMA-DT dimethylamino groups on binding to three vertebrate nAChRs. Radioligand receptor binding experiments were carried out using washed membranes from rat brain and fish (Torpedo) electric organ; [3H]-cytisine displacement was used to assess binding to the predominantly high affinity alpha4beta2 nAChRs and [125I]-alpha-bungarotoxin displacement was used to measure binding of NTX and analogs to the alpha7 and skeletal muscle type nAChRs. While the two quaternary nitrogen analogs, relative to their respective tertiary amines, displayed lower α4β2 nAChR binding affinities, both displayed much higher affinities for the Torpedo muscle nAChR and rat alpha7 brain receptors than their respective tertiary amine forms. The binding affinities of DMA-DT for the three nAChRs were lower than those of NTX and MeNTX. An AChBP mutant lacking the C loop disulfide bond that would potentially react with the NTX disulfide bond displayed an NTX affinity very similar to the parent AChBP. Inhibition of [3H]-epibatidine binding to the AChBPs was not affected by exposure to NTX or MeNTX for up to 24 hr prior to addition of the radioligand. Thus, the disulfide bond of NTX is not required to react with the vicinal disulfide in the AChBP C loop for inhibition of [3H]-epibatidine binding. However, a reversible disulfide interchange reaction of NTX with nAChRs might still occur, especially under reducing conditions. Labeled MeNTX, because it can be readily prepared with high specific radioactivity and possesses relatively high affinity for the nAChR-rich Torpedo nAChR, would be a useful probe to detect and identify any nereistoxin adducts.

scholarly journals Selective cytotoxicity of 125I-labeled monoclonal antibody T101 in human malignant T cell lines

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 429-435
Author(s):  
E Boven ◽  
T Lindmo ◽  
JB Mitchell ◽  
PA Jr Bunn
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
High Specific Activity ◽  
Tumor Localization ◽  
Cytotoxic Effects ◽  
High Specific Radioactivity ◽  
T Cell Lines

The radiolabeled anti-T cell antibody T101 can be used for specific tumor localization, but unlabeled T101 produces limited cytotoxicity in patients. We thus studied the in vitro cytotoxic effects of T101 labeled with 125I, a radionuclide known for its short-range, high- linear-energy electrons. We showed that 125I-T101 could be readily prepared at high specific activity with high immunoreactivity. Human malignant T cell lines HUT 102, MOLT-4, and HUT 78 were found to differ in the number of T65 determinants (the antigen recognized by T101) and the sensitivity to external x-ray radiation, which were of significance for the cytotoxicity of 125I-T101 in vitro. The cytotoxic effects of 125I-T101 were also found to be dose dependent and increased with exposure time under frozen conditions. As controls, unlabeled T101 had no cytotoxic effect, while free Na 125I or the 125I-labeled irrelevant antibody 9.2.27 exerted minor cytotoxicity. In HUT 102 and MOLT-4, more than 3 logs' cell killing was achieved within four weeks. Because considerable cytotoxicity was demonstrated in vitro by 125I-T101 on T65- positive malignant cells, and because low-dose 111In-T101 can be used successfully for tumor localization, future trials using 125I-T101 at high specific radioactivity may improve therapeutic results in patients with T65-positive malignancies.

Properties of Polyoma virus-transformed cells II. Characteristics of the virus-specific RNA

1972 ◽  
Vol 18 (2) ◽  
pp. 247-254
Author(s):  
James B. Hudson
Keyword(s):  
Dna Hybridization ◽  
Infectious Virus ◽  
Specific Radioactivity ◽  
Polyoma Virus ◽  
Transformed Cells ◽  
Viral Genomes ◽  
High Specific Radioactivity ◽  
Mouse Cells ◽  
Covalently Linked ◽  
Competition Hybridization

The Polyoma virus-specific RNA (PyRNA) synthesized in a line of Polyoma-transformed hamster cells, was analyzed and compared with the viral-specific RNA synthesized "late" in productively infected mouse cells. The PyRNA from the transformed cells sedimented heterogeneously on sucrose gradients, including appreciable amounts of PyRNA in the > 40-S region. The overall sedimentation profile resembled that of "late" PyRNA synthesized in mouse cells. Competition hybridization experiments, however, revealed that the bulk of the PyRNA sequences in the transformed cells were different from "late" PyRNA sequences. The use of DNA–DNA hybridization experiments (with Polyoma DNA of high specific radioactivity) enabled an estimate to be made of the average number of viral genomes per transformed cell. No more than two, and possibly less than one, complete genomes were found. These studies support the hypothesis that this line of Polyoma transformed cells contains an incomplete genome, possibly only comprising "early" genes (hence the inability to rescue infectious virus), and that the viral RNA transcribed is covalently linked to host cell RNA moieties.

METABOLISM IN VITRO OF TRITIATED ADRENOCORTICOTROPIC HORMONE

1965 ◽  
Vol 43 (9) ◽  
pp. 1489-1498 ◽  
Author(s):  
Edward E. Nishizawa ◽  
R. B. Billiar ◽  
J. Karr ◽  
Kristen B. Eik-Nes
Keyword(s):  
Biological Activity ◽  
Adrenal Gland ◽  
Adrenal Cortex ◽  
Enzymatic Degradation ◽  
Adrenocorticotropic Hormone ◽  
Specific Radioactivity ◽  
Adrenocorticotrophic Hormone ◽  
Serine Residue

Adrenocorticotrophic hormone (ACTH) labeled with tritium has been prepared with a specific radioactivity of approximately 4000 d.p.m./μg. The tritiated trophin showed biological activity and appeared to be bound to the cells of the adrenal gland. Data indicating that the adrenal cortex can inactivate ACTH were obtained; whether such inactivation is due to binding or enzymatic degradation has not been illustrated. Attempts to demonstrate that the adrenal gland could acetylate the N-terminal serine residue of ACTH failed.

Nutrient cycling in grazed pastures.IV.The fate of sulphur-35 following its application to a small area in a grazed pasture

1971 ◽  
Vol 22 (3) ◽  
pp. 391 ◽  
Author(s):  
AR Till ◽  
PF May
Keyword(s):  
Nutrient Cycling ◽  
Small Area ◽  
Specific Radioactivity ◽  
Positive Evidence ◽  
Grazed Pasture ◽  
Simultaneous Measurements ◽  
Organic Sulphur ◽  
High Specific Radioactivity ◽  
Wide Range ◽  
Extractable Soil

Simultaneous measurements of sulphur content and specific radioactivity were made on soil fractions, two pasture species, and the fleece of grazing animals following the application of high specific radioactivity gypsum labelled with sulphur-35 (35S) to small randomly located sites in grazed pastures. The results show that the extractable soil sulphate was a precursor of plant sulphur and that the organic sulphur fractions in the soil were the source of replenishment of the extractable sulphate pool. Applied sulphur was shown to remain predominantly in the top 7.5 cm of the soil over a period of c. 600 days, and it was from this region that the plants drew their sulphur. The uptake of applied sulphur was initially different between plants of different species. These differences gradually decreased and finally disappeared as the applied sulphur became mixed into all soil sulphur fractions. A wide range of rates of mixing indicated that some fractions of the organic sulphur were recycling very slowly. Positive evidence of recycling of sulphur voided by the animals on the unlabelled areas of the pasture was found, and the rate of translocation of sulphur from the sites of its application to the remainder of the paddock was measured at two rates of stocking.

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