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Biomedical subjects

M E Wolff

Publications and source records attributed to M E Wolff.

At least 37 records · Page 2Linked to original sources
PubMed1976

Photoaffinity site-specific covalent labeling of human corticosteroid-binding globulin.

A method was developed for the synthesis of high-specific-activity 21-diazo-21-[6,7-(3)H]deoxycorticosterone, an analog of corticosterone. This analog was used as a photoaffinity label of a high affinity steroid-binding protein, human corticosteroid-binding globulin. Based on direct binding studies and crosscompetition experiments, this diazo derivative exhibited the requisite affinity (within a factor of 1.5 times that of corticosterone) and site specificity to qualify as an affinity labeling legand. Irradiation of corticosteroid-binding globulin with the 21-diazo derivative resulted in irreversible binding to corticosteroid-binding globulin, identified by polyacrylamide gel electrophoresis. Specificity of covalent binding to corticosteroid-binding globulin was established by competition analysis with various steroids. Irreversibility of photodependent binding was shown by persistence of the complex on electrophoresis (in contrast to the noncovalently linked complex), and resistance to exchange with corticosterone or pregnanediol and to solvent extraction. Site specificity of covalent binding was inferred from the effects of a scavenger, Tris-HC1, and fluorescence quenching of a neighboring tryptophan.

Affinity Labels↗
PubMed1975

Steroidal 21-diazo ketones: photogenerated corticosteroid receptor labels.

The 21-diazo derivatives of 9 alpha-fluoro- and 9 alpha-bromo-21 deoxycorticosterone, 21-deoxycorticosterone, and progesterone were synthesized for use as photoaffinity labels for corticosteroid receptors. In the isolated toad bladder system, 9 alpha-bromo-21-diazo-21-deoxycorticosterone was as active as d-aldosterone and more active than 9 alpha-fluoro-cortisol in augmenting active Na+ transport. The activities of 21-diazoprogesterone and progesterone were equal; both were much less potent than d-aldosterone, however. These results indicate that the 21-diazo derivatives had significant functional activity in the toad bladder system. The rat kidney slice system was used to estimate the relative affinities of the diazo steroids for aldosterone receptor sites by competition experiments. At 100-fold excess of competitor to [3-H]aldosterone, the order of affinities was 9 alpha-fluoro-21-diazo-21-deoxycorticosterone greater than 9 alpha-bromo-21-diazo-21-deoxycorticosterone greater than 21-diazoprogesterone. Moreover, 9 alpha-bromo-21-diazo-21-deoxycorticosterone reduced binding of [3-H]aldosterone to cytoplasmic and nuclear forms of the receptor proportionately. On the basis of competition for [3-H]corticosterone binding, presumably to corticosteroid-binding globulin (CBG), the order of affinities was 21-diazo-21-deoxycorticosterone greater than 21-diazoprogesterone greater than 9 alpha-bromo-21-diazo-21-deoxycorticosterone. These findings indicate that 21-diazo steroids may be suitable as photogenerated affinity labels for mineralocorticoid receptors. The tritiated derivative, [1,2-3-H]-9 alpha-bromo-21-diazo-21-deoxycorticosterone (specific activity 25 Ci/mol) was synthesized and used in model experiments on photogenerated covalent binding to rat plasma proteins. Irradiation with uv light resulted in binding of [1,2-3-H]-9 alpha-bromo-21-diazo-21-deoxycorticosterone to plasma proteins, that was resistant to extraction with methylene dichloride and did not exchange with unlabeled corticosterone. The diazocorticosteroids, therefore, may have the requisite functional and selectivity properties for photoaffinity labeling of corticosteroid-binding proteins. Further studies are needed, however, to assure that photogenerated labeling with these steroids was site specific.

Animals↗
PubMed1975

[Localization and identification of the LH-RF center in the brain of the toad, Bufo vulgaris Laur].

Using indirect immunofluorescence procedure with an anti-synthetic LHRF serum, pericarya of neurons producing LHRF or an LHRF-like substance were revealed in hypophysectomized Bufo vulgaris. They are localized principally in the forebrain near the posterior end of the first and second ventricles. The fluorescent axons coming from these pericarya are visible on their pathway to a region near tha pars tuberalis and to the median eminence.

Animals↗
PubMed1975

[Establishment of a primary culture of cells from embryonic tissue of Loliyo vulgaris L.(Cephalopod)].

The author studies the behaviour in vitro of organ fragments of Loligo vulgaris embryos at hatching stage. These fragments are maintained in three different media. The time of survival of cells is 20 to 25 days in the medium I(sea water), 40 days in the medium II(perivitellin fluid) and 70 to 80 days in the medium II(perivetellin fluid + horse serum). It is this medium III that the original explant is transformed into a typical primary cell culture.

Animals↗