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The synthesis of tritium-labelled human corticotropin of high specific radioactivity.

ABSTRACT: Human [[3,5-3H2]Tyr23]corticotropin-(1-39)-nonatriacontapeptide of specific radioactivity 25.2 Ci/mmol, identical with unlabelled human corticotropin by several criteria, was prepared via the fully protected di-iodotyrosine compound. The latter was synthesized by classical procedures.

SUBMITTER: Brundish DE

PROVIDER: S-EPMC1164883 | biostudies-other | 1977 Jul

REPOSITORIES: biostudies-other

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Synthesis of tritium-labelled isopenicillin N, penicillin N and 6-aminopenicillanic acid.

Project description:1. Phenoxymethylpenicillin sulphoxide 4-methoxybenzyl ester was labelled with 3H in its 2-beta-methyl group. Its specific radioactivity was 362 mCi/mmol. 2. Removal of the side chain of this compound yielded the corresponding ester of 6-aminopenicillanic acid sulphoxide and coupling of the latter with the appropriate protected alpha-aminoadipic acid gave 4-methoxybenzyloxycarbonylisopenicillin N sulphoxide di-4-methoxybenzyl ester or the corresponding derivative of penicillin N. 3. Removal of the protective groups by hydrogenolysis and reduction of the sulphoxide group yielded 3H-labelled isopenicillin N or penicillin N. 4. 3H-labelled phenoxymethylpenicillin sulphoxide was obtained by hydrogenolysis from its 4-methoxybenzyl ester. Reduction of its sulphoxide group and subsequent removal of the side chain gave 3H-labelled 6-aminopenicillanic acid.

| S-EPMC1172422 | biostudies-other

New synthesis and tritium labeling of a selective ligand for studying high-affinity ?-hydroxybutyrate (GHB) binding sites.

Project description:3-Hydroxycyclopent-1-enecarboxylic acid (HOCPCA, 1) is a potent ligand for the high-affinity GHB binding sites in the CNS. An improved synthesis of 1 together with a very efficient synthesis of [(3)H]-1 is described. The radiosynthesis employs in situ generated lithium trimethoxyborotritide. Screening of 1 against different CNS targets establishes a high selectivity, and we demonstrate in vivo brain penetration. In vitro characterization of [(3)H]-1 binding shows high specificity to the high-affinity GHB binding sites.

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Preclinical Pharmacokinetic Studies of the Tritium Labelled D-Enantiomeric Peptide D3 Developed for the Treatment of Alzheimer´s Disease.

Project description:Targeting toxic amyloid beta (Aβ) oligomers is currently a very attractive drug development strategy for treatment of Alzheimer´s disease. Using mirror-image phage display against Aβ1-42, we have previously identified the fully D-enantiomeric peptide D3, which is able to eliminate Aβ oligomers and has proven therapeutic potential in transgenic Alzheimer´s disease animal models. However, there is little information on the pharmacokinetic behaviour of D-enantiomeric peptides in general. Therefore, we conducted experiments with the tritium labelled D-peptide D3 (3H-D3) in mice with different administration routes to study its distribution in liver, kidney, brain, plasma and gastrointestinal tract, as well as its bioavailability by i.p. and p.o. administration. In addition, we investigated the metabolic stability in liver microsomes, mouse plasma, brain, liver and kidney homogenates, and estimated the plasma protein binding. Based on its high stability and long biological half-life, our pharmacokinetic results support the therapeutic potential of D-peptides in general, with D3 being a new promising drug candidate for Alzheimer´s disease treatment.

| S-EPMC4457900 | biostudies-literature

A simple assay method for determination of the specific radioactivity of the gamma-phosphate group of 32P-labelled ATP.

Project description:A simple and rapid assay method is described for determining the specific radioactivity of the gamma-phosphate group of 32P-labelled ATP. Labelled ATP is incubated with cyclic AMP, cyclic AMP-dependent protein kinase and histone H2A under conditions leading to maximum phosphorylation of the histone. The specific radioactivity of the gamma-phosphate group of the 32P-labelled ATP is calculated from the total amount of [32P]Pi incorporated into a standard amount of histone. This assay method uses inexpensive commercially available materials, and it yields an accurate specific radioactivity with as little as 0.25 nmol of 32P-labelled ATP.

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Natural radioactivity and human mitochondrial DNA mutations.

Project description:Radioactivity is known to induce tumors, chromosome lesions, and minisatellite length mutations, but its effects on the DNA sequence have not previously been studied. A coastal peninsula in Kerala (India) contains the world's highest level of natural radioactivity in a densely populated area, offering an opportunity to characterize radiation-associated DNA mutations. We sampled 248 pedigrees (988 individuals) in the high-radiation peninsula and in nearby low-radiation islands as a control population. We sequenced their mtDNA, and found that the pedigrees living in the high-radiation area have significantly (P < 0.01) increased germ-line point mutations between mothers and their offspring. In each mutation case, we confirmed maternity by autosomal profiling. Strikingly, the radioactive conditions accelerate mutations at nucleotide positions that have been evolutionary hot spots for at least 60,000 years.

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The specific radioactivity of the precursor pool for estimates of the rate of protein synthesis.

Project description:Infusion of rats with [U-(14)C]glycine resulted in labelling of glycine and serine in tissue proteins. The pattern of labelling in protein more nearly resembled that of the free amino acids in the tissue than in the plasma.

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Synthesis of deuterium-labelled amlexanox and its metabolic stability against mouse, rat, and human microsomes.

Project description:As part of a program toward making analogues of amlexanox (1), currently under clinical investigation for the treatment of type 2 diabetes and obesity, we have synthesized derivative 5 in which deuterium has been introduced into two sites of metabolism on the C-7 isopropyl function of amlexanox. The synthesis of 5 was completed in an efficient three-step process utilizing reduction of key olefin 7b to 8 by Wilkinson's catalyst to provide specific incorporation of di-deuterium across the double bond. Compound 5 displayed nearly equivalent potency to amlexanox (IC50 , 1.1μM vs 0.6μM, respectively) against recombinant human TBK1. When incubated with human, rat, and mouse liver microsomes, amlexanox (1) and d2 -amlexanox (5) were stable (t1/2 > 60 minutes) with 1 showing marginally greater stability relative to 5 except for rat liver microsomes. These data show that incorporating deuterium into two sites of metabolism does not majorly suppress Cyp-mediated metabolism relative to amlexanox.

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Synthesis of <sup>15</sup> N-labelled 3,5-dimethylpyridine.

Project description:15 N-labelled pyridines are liquid- and solid-state nuclear magnetic resonance (NMR) probes for chemical and biological environments because their 15 N chemical shifts are sensitive to hydrogen-bond and protonation states. By variation of the type and number of substituents, different target pyridines can be synthesized exhibiting different pKa values and molecular volumes. Various synthetic routes have been described in the literature, starting from different precursors or modification of other 15 N-labelled pyridines. In this work, we have explored the synthesis of 15 N 15 N-labelled pyridines using a two-step process via the synthesis of alkoxy-3,4-dihydro-2H-pyran as precursor exhibiting already the desired pyridine substitution pattern. As an example, we have synthesized 3,5-dimethylpyridine-15 N (lutidine-15 N) as demonstrated by 15 N-NMR spectroscopy. That synthesis starts from methacrolein, propenyl ether, and 15 N-labelled NH4 Cl as nitrogen source.

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Human gamma-melanotropin precursor potentiates corticotropin-induced adrenal steroidogenesis by stimulating mRNA synthesis.

Project description:Circulating human gamma-melanotropin precursor (76 amino acids) [N-POC(1-76) enhances the corticosterone and aldosterone response to corticotropin by isolated perfused rat adrenal cells [Al-Dujaili, Hope, Estivariz, Lowry & Edwards (1981) Nature (London) 291, 156-159]. Actinomycin D (4 x 10(-6) mol/litre) did not significantly affect corticotropin-induced corticosterone or aldosterone outputs, but completely inhibited the potentiating action of gamma-melanotropin precursor on rat adrenal cells. This suggests that the precursor enhances corticotropin-induced steroidogenesis via an increase in available mRNA produced from DNA transcription.

| S-EPMC1158345 | biostudies-other

The sources of high airborne radioactivity in cryoconite holes from the Caucasus (Georgia).

Project description:Cryoconite granules are mixtures of mineral particles, organic substances and organisms on the surface of glaciers where they decrease the ice albedo and are responsible for formation of water-filled holes. The contaminants are effectively trapped in the cryoconite granules and stay there for many years. This study evaluates the contamination level of artificial and natural radionuclides in cryoconite holes from Adishi glacier (Georgia) and identifies the sources of contamination based on activity or mass ratios among artificial radionuclides. Results revealed high activity concentrations of fallout radionuclides reaching 4900?Bq/kg, 2.5?Bq/kg, 107?Bq/kg and 68?Bq/kg for 137Cs, 238Pu, 239+240Pu and 241Am, respectively. The main source of Pu is global fallout, but the low 240Pu/239Pu atomic ratios also indicated local tropospheric source of 239Pu, probably from the Kapustin Yar nuclear test site. Also, high activity ratios of 241Am/239+240Pu could originate from Kapustin Yar. The natural radionuclides originate from the surrounding rocks and were measured to control the environmental processes. 210Pb in cryoconite granules comes predominantly from the atmospheric deposition, and its activity concentrations reach high values up to 12000?Bq/kg.

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