THE IN VITRO BIOSYNTHESIS OF ESTRADIOL-17β-4-C14BY SURVIVING NORMAL AND STEIN–LEVENTHAL-TYPE OVARIAN SLICES

1963 ◽  
Vol 41 (3) ◽  
pp. 635-647 ◽  
Author(s):  
Alcide Chapdelaine ◽  
Thomas Sandor ◽  
André Lanthier
Keyword(s):  
Quantitative Difference ◽  
Human Chorionic Gonadotrophin ◽  
Isotopic Dilution ◽  
Tissue Slices ◽  
Medium Ph ◽  
Experimental Conditions ◽  
Chemical Derivatives ◽  
In Vitro Biosynthesis ◽  
Estradiol 17Β

The biological aromatization of androstenedione-4-C14, testosterone-4-C14, and dehydroepiandrosterone-4-C14by surviving human normal and Stein–Leventhal-type ovarian slices was investigated. The precursors were incubated with the tissue slices in a Krebs–Ringer–phosphate–glucose medium (pH 7.4) in an O2atmosphere at 37 °C for 6 and (or) 24 hours. As a cofactor, 1000 I.U. of human chorionic gonadotrophin was added to each incubation vessel. Both normal and polymicrocystic ovarian slices transformed the precursors partially to estradiol-17β. This compound was identified by isotopic dilution techniques and by the constancy of specific activities of its chemical derivatives. There was no significant qualitative or quantitative difference in the aromatization capacity of the two kinds of tissue. In addition, biosynthetic androstenedione-4-C14and testo-sterone-4-C14were positively identified. These experiments seem to indicate that under the experimental conditions used, the aromatization mechanism is functioning normally in Stein–Leventhal-type ovaries.

THE IN VITRO BIOSYNTHESIS OF ESTRADIOL-17β-4-C14BY SURVIVING NORMAL AND STEIN–LEVENTHAL-TYPE OVARIAN SLICES

1963 ◽  
Vol 41 (1) ◽  
pp. 635-647
Author(s):  
Alcide Chapdelaine ◽  
Thomas Sandor ◽  
André Lanthier
Keyword(s):  
Quantitative Difference ◽  
Human Chorionic Gonadotrophin ◽  
Isotopic Dilution ◽  
Tissue Slices ◽  
Medium Ph ◽  
Experimental Conditions ◽  
Chemical Derivatives ◽  
In Vitro Biosynthesis ◽  
Estradiol 17Β

The biological aromatization of androstenedione-4-C14, testosterone-4-C14, and dehydroepiandrosterone-4-C14by surviving human normal and Stein–Leventhal-type ovarian slices was investigated. The precursors were incubated with the tissue slices in a Krebs–Ringer–phosphate–glucose medium (pH 7.4) in an O2atmosphere at 37 °C for 6 and (or) 24 hours. As a cofactor, 1000 I.U. of human chorionic gonadotrophin was added to each incubation vessel. Both normal and polymicrocystic ovarian slices transformed the precursors partially to estradiol-17β. This compound was identified by isotopic dilution techniques and by the constancy of specific activities of its chemical derivatives. There was no significant qualitative or quantitative difference in the aromatization capacity of the two kinds of tissue. In addition, biosynthetic androstenedione-4-C14and testo-sterone-4-C14were positively identified. These experiments seem to indicate that under the experimental conditions used, the aromatization mechanism is functioning normally in Stein–Leventhal-type ovaries.

THE IN VITRO BIOSYNTHESIS OF 18-HYDROXYCORTICOSTERONE-4-14C BY SLICES OF ZONA GLOMERULOSA OF BEEF ADRENALS AND BY HUMAN ADRENALS

1963 ◽  
Vol 42 (3) ◽  
pp. 355-363 ◽  
Author(s):  
Thomas Sandor ◽  
André Lanthier
Keyword(s):  
Closed Form ◽  
Transformation Products ◽  
Zona Glomerulosa ◽  
Isotopic Dilution ◽  
Tissue Slices ◽  
Inactive Carrier ◽  
Tautomeric Forms ◽  
The Media ◽  
In Vitro Biosynthesis

ABSTRACT The in vitro steroidogenesis of the zona glomerulosa of beef adrenals and that of human adrenals was investigated. Tissue slices were incubated in a Krebs-Ringer - bicarbonate medium containing 200 mg% of glucose with progesterone-4-14C and corticosterone-4-14C as precursors. After incubation the media were extracted exhaustively with chloroform and the dry residue of the solvent extract fractionated on paper chromatographic systems. The identity of one of the 14C transformation products produced from both precursors was investigated in detail. The substance absorbed ultraviolet light (λmaxEtOH: 241 mμ), but reduced alkaline blue tetrazolium only very slowly. The mobility of the unknown alone and diluted with inactive carrier was identical with that of the 20→ 18 cyclic hemiketal of 18-hydroxycorticosterone. The identity of the biosynthetic material with the closed form of 18-hydroxycorticosterone was established by isotopic dilution techniques and the formation of derivatives. It was observed that the compound can exist in at least three different tautomeric forms. The yield of 18-hydroxycorticosterone with beef zona glomerulosa was 3.8% from progesterone and 6.8% from corticosterone.

In vitro biosynthesis of steroid sulfates by cell-free preparations from tissues of the laying hen

1968 ◽  
Vol 46 (8) ◽  
pp. 749-757 ◽  
Author(s):  
H. R. Raud ◽  
R. Hobkirk
Keyword(s):  
Enzyme System ◽  
Laying Hen ◽  
Product Identification ◽  
Temperature Requirements ◽  
Before And After ◽  
Liver Preparation ◽  
Steroid Sulfate ◽  
In Vitro Biosynthesis ◽  
Estradiol 17Β

The sulfurylation of estrone-6,7-3H, estradiol-17β-6,7-3H, and dehydroisoandrosterone-4-14C by laying hen liver, oviduct, and vaginal preparations was investigated. Purification and product identification included ether and ethyl acetate extraction, paper chromatography, and isotope dilution, before and after hydrolysis with a sulfatase preparation.The esterifying enzymes were found in the 105 000 × g supernatants of the three tissues. The liver preparation was many times more active in steroid sulfate synthesis than the corresponding oviduct or vaginal fractions. Sulfurylation of dehydroisoandrosterone displayed the same cofactor, pH, and temperature requirements as did that of estrone and estradiol-17β. The degree of dehydroisoandrosterone sulfate synthesis was considerably lower than that of the estrogens, however. It is suggested that the laying hen possesses an enzyme system which is more efficient for the sulfurylation of estrogens than of other steroids such as dehydroisoandrosterone.

Effects of hypophysectomy and subsequent FSH and testosterone treatment on inhibin production by adult rat testes

1985 ◽  
Vol 105 (1) ◽  
pp. 1-6 ◽  
Author(s):  
C. L. Au ◽  
D. M. Robertson ◽  
D. M. de Kretser
Keyword(s):  
Seminiferous Tubule ◽  
Hormonal Control ◽  
Human Chorionic Gonadotrophin ◽  
Experimental Conditions ◽  
Adult Rats ◽  
Adult Rat ◽  
Fluid Production ◽  
Tubule Fluid

ABSTRACT The hormonal control of inhibin production by adult rat testes was investigated using an in-vitro inhibin bioassay validated for the measurement of inhibin activity in charcoal-treated rat testicular extracts. The effect of hypophysectomy examined at 16 h, 3, 7 and 42 days after surgery showed a decrease in testicular inhibin content and seminiferous tubule fluid production by 7 days and a decrease in inhibin production by 42 days. Serum FSH and LH were suppressed 3 days after surgery. In 30-day chronically hypophysectomized adult rats treated for 3 days with twice daily s.c. injections of (a) human FSH (hFSH, 22 i.u./rat per day), (b) testosterone (5 mg/rat per day), (c) hFSH + testosterone (same doses as a and b), or (d) human chorionic gonadotrophin (hCG, 12 i.u./rat per day), hFSH or hFSH and testosterone stimulated an increase in testicular inhibin content but not in inhibin production or tubule fluid production. Testosterone and hCG had no effect on these parameters. It is concluded that in vivo, FSH alone stimulates an increase in testicular inhibin content. The failure to observe an increase in inhibin production in vivo is attributed to the suppression of seminiferous tubule fluid production under the same experimental conditions. J. Endocr. (1985) 105, 1–6

In Vitro Synthesis of Estrogen Glucuronides and Sulfates by Human Renal Tissue

1975 ◽  
Vol 53 (7) ◽  
pp. 779-783 ◽  
Author(s):  
Joyce D. Mellor ◽  
R. Hobkirk
Keyword(s):  
Renal Tissue ◽  
In Vivo Studies ◽  
Time Study ◽  
Tissue Slices ◽  
Experimental Conditions ◽  
In Vitro Synthesis ◽  
Estrone Sulfate ◽  
Layer Chromatography

17β-[6,7-3H]Estradiol (E2) was incubated with slices and homogenates of adult human renal tissue. The metabolites formed were identified by chromatography on DEAE-Sephadex, thin layer chromatography and crystallization with carrier steroids or steroid derivatives. The major metabolites formed by slices were estradiol-17-glucuronide (E217G), estrone sulfate and estradiol-3-sulfate. This is the first report of in vitro synthesis of estrogen sulfates by adult renal tissue. Minor quantities of the 3-glucuronides of estrone and estradiol were also found. An oxygen atmosphere appeared to stimulate the production of E217G. A time study with tissue slices showed similarities between the in vitro pattern of glucuronide synthesis and the excretion pattern of these compounds seen in earlier in vivo studies. Homogenates fortified with uridine diphosphoglucuronic acid formed the same pattern of glucuronide products but in lesser amounts. No sulfates were formed under these conditions. Testosterone did not act as a substrate in the experimental conditions used.

THE IN VITRO BIOSYNTHESIS OF ANDROGENIC STEROIDS BY HUMAN NORMAL AND »STEIN-LEVENTHAL TYPE« OVARIAN SLICES

1962 ◽  
Vol 39 (1) ◽  
pp. 145-153 ◽  
Author(s):  
André Lanthier ◽  
Thomas Sandor
Keyword(s):  
Paper Chromatography ◽  
Metabolic Activity ◽  
Transformation Products ◽  
Glucose Medium ◽  
Chromatographic Mobility ◽  
Tissue Slices ◽  
Mobility Studies ◽  
In Vitro Biosynthesis ◽  
Androgenic Steroids

ABSTRACT The in vitro biosynthesis of androgenic steroids by surviving human normal and »Stein-Leventhal type« ovarian slices was studied. The tissue slices were incubated in a Krebs-Ringer-phosphate-glucose medium (pH: 7.4) with pregnenolone, progesterone, 17α-hydroxyprogesterone and androstenedione added as substrates. The incubations were supplied with HCG as cofactor (1000 IU/vessel) and the reactions left to proceed for 6 or 24 hours. After incubation, the medium was extracted with chloroform and transformation products isolated by paper chromatography. Individual substances were characterized by chromatographic mobility studies, preparation of derivatives and spectrophotometric techniques. The following results were obtained: qualitatively no differences could be noted between the metabolic activity of ovarian slices of either origin. Quantitatively, »Stein-Leventhal type« slices showed an accelerated rate of production in all intermediary reactions, especially in the production of androstenedione and testosterone. In addition to the direct intermediaries, four C20 reduced transformation products of progesterone and 17α-hydroxyprogesterone were isolated from experiments involving both normal and micropolycystic ovarian slices.

in vitro biosynthesis of radioactive estradiol-17β, 17-glucosiduronate by rhesus monkey liver

Steroids ◽  
1977 ◽  
Vol 30 (2) ◽  
pp. 267-274 ◽  
Author(s):  
P.I. Musey ◽  
D.C. Collins ◽  
J.R.K. Preedy
Keyword(s):  
Rhesus Monkey ◽  
Monkey Liver ◽  
In Vitro Biosynthesis ◽  
Estradiol 17Β

CHARACTERISTICS OF THE FORMATION AND CONVERSION OF ANDROGENIC HORMONES IN THE RAT ADRENAL GLAND

1971 ◽  
Vol 66 (4) ◽  
pp. 727-736
Author(s):  
O. Koref ◽  
K. Steczek ◽  
T. Fehér
Keyword(s):  
Adrenal Gland ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Hydroxylase Activity ◽  
Experimental Conditions ◽  
Atp Inhibition

ABSTRACT Incubated rat adrenal slices failed to convert cholesterol, pregnenolone and 17-OH-progesterone into C19-steroids under the experimental conditions used. Dehydroepiandrosterone was converted to androstenedione and 11-OH-androstenedione. The formation of androstenedione and 11-OH-androstenedione could also be demonstrated by using testosterone precursor. Corticotrophin in vitro did not affect the rate of conversion and the amount of 11-hydroxylated derivative increased when ATP was also added to the medium. Human chorionic gonadotrophin enhanced 11-hydroxylation in the presence of ATP. Inhibition of 11β-hydroxylase activity by metopirone was not affected by ATP.

Observations of Frozen-Hydrated Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 504-505
Author(s):  
D. Chrétien ◽  
D. Job ◽  
R.H. Wade
Keyword(s):  
Fourier Transforms ◽  
Structural Complexity ◽  
Image Contrast ◽  
Phase Behaviour ◽  
Experimental Conditions ◽  
Thin Sections ◽  
Surface Lattice ◽  
Cilia And Flagella ◽  
Outstanding Question

Microtubules are filamentary structures found in the cytoplasm of eukaryotic cells, where, together with actin and intermediate filaments, they form the components of the cytoskeleton. They have many functions and show various levels of structural complexity as witnessed by the singlet, doublet and triplet structures involved in the architecture of centrioles, basal bodies, cilia and flagella. The accepted microtubule model consists of a 25 nm diameter hollow tube with a wall made up of 13 paraxial protofilaments (pf). Each pf is a string of aligned tubulin dimers. Some results have suggested that the pfs follow a superhelix. To understand how microtubules function in the cell an accurate model of the surface lattice is one of the requirements. For example the 9x2 architecture of the axoneme will depend on the organisation of its component microtubules. We should also note that microtubules with different numbers of pfs have been observed in thin sections of cellular and of in-vitro material. An outstanding question is how does the surface lattice adjust to these different pf numbers?We have been using cryo-electron microscopy of frozen-hydrated samples to study in-vitro assembled microtubules. The experimental conditions are described in detail in this reference. The results obtained in conjunction with thin sections of similar specimens and with axoneme outer doublet fragments have already allowed us to characterise the image contrast of 13, 14 and 15 pf microtubules on the basis of the measured image widths, of the the image contrast symmetry and of the amplitude and phase behaviour along the equator in the computed Fourier transforms. The contrast variations along individual microtubule images can be interpreted in terms of the geometry of the microtubule surface lattice. We can extend these results and make some reasonable predictions about the probable surface lattices in the case of other pf numbers, see Table 1. Figure 1 shows observed images with which these predictions can be compared.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

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