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Biomedical subjects

S S Koide

Publications and source records attributed to S S Koide.

At least 127 records · Page 7Linked to original sources
PubMed1985

Early stimulation of phospholipid methylation in Xenopus oocytes by progesterone.

Progesterone induced a transient increase in the incorporation of [3H]methyl groups into phospholipids of Xenopus oocytes followed by a rise in 45Ca2+ uptake. Phospholipid methylation reached a maximum as early as 15 s after progesterone treatment and returned to basal level within 2 min. Steroids inactive in promoting oocyte maturation were less effective in affecting phospholipid methylation. Methyltransferase inhibitors, 3-deaza-SIBA, SIBA, and Sinefungin, inhibited progesterone-activated stimulation of phospholipid methylation, calcium uptake and meiotic maturation. Phospholipid methylation is the earliest detectable biochemical event occurring in oocytes after exposure to progesterone followed by calcium influx and leading to germinal vesicle dissolution.

Adenosine↗
PubMed1985

Biological activity of the unique variants of human chorionic gonadotropin in choriocarcinoma tissue.

Human chorionic gonadotropin (hCG) in sera and placentae from normal pregnant women separated into 7 variants on analysis by an isoelectric focusing technique and determined by radioimmunoassay. The pIs ranged from 3.9 to 7.0. Three additional acidic variants were found in the sera and tumor tissues of patients with choriocarcinoma with pIs of 3.2, 3.5 and 3.7. The biological activity of each variant was determined by measuring testosterone production by rat Leydig cells in vitro. The pI 4.1 fraction corresponding to placental hCG possessed the highest biological activity while those focusing further afield from pI 4.1 showed decreasing activities. All 3 tumor unique acidic variants possessed biological activity with the fraction focusing at pI 3.7 having the greatest potency.

Biological Assay↗
PubMed1985

Interaction of 14 C-gossypol with human sperm.

Gossypol, a bis-sesquiterpene, suppresses spermatogenesis and inhibits sperm motility. The direct interaction of gossypol with human sperm was investigated. Conditions influencing the interaction of 14c-gossypol (radiolabeled on the aldehyde group with specific activity of 3.33 x 10 5 dpm per micromole) with human sperm reached saturation rapidly. Within 1 minute of exposure of motile sperm to 10 uM radiolabeled gossypol at 37 degrees Centigrade, the cincorporation of 14c-gossyol was 17 at 35% at densities of 2.5 x 106 and 8.6 x 106 per ml, respectively. Immobile sperm prepared by heating at 60 degrees Centigrade for 10 minutes incorporated the same amount of 14c-gossypol as motile sperm. Uptake of 14c-gossypol was slightly greater at 37 degrees Centigrade than at 4 degrees Centigrade, and under acidic conditions. To identify the sperm membrane components interacting with gossypol radiolabeled sperm were treated with the following 3 solutions to solubilize the membrane proteins: 0.1% Triton X-100; 1 M urea, 5 mM EDTA in 19mM Tris-HC1, pH 8.3; and 20% sodium doydecyl sulfate (SDS), 0.1M 20mercaptoethanol. The amount of radiolabeled proteins solubilized with respective media were 11, 23, and 67% with specific activities of 1.8 x 103, 2.1 x 105, and 0.3 x 103 cpm per mg protein. The radiolabeled substances solubilized with SDS, mercaptoethanol reagent were separated by gel filtration on Sephadex G-100 column. 3 peaks of radioactivities corresponding to molecular weights of approximately 100, 35, and 25 KD were eluted. The highest radioactivity was found with the 100 KD fraction. The interaction of gossypol with sperm membrane proteins is an early event, followed by inhibition of sperm motility.

Contraception↗
PubMed1984

Mechanism of the inhibition of Ca2+, Mg2+-dependent endonuclease of bull seminal plasma induced by ADP-ribosylation.

The activity of purified Ca2+, Mg2+-dependent endonuclease was inhibited when the enzyme was incubated in a system containing poly(ADP-ribose) synthetase, NAD+, Mg2+, and DNA. All four ingredients were essential to mediate ADP-ribosylation and to demonstrate inhibition of the endonuclease. In the absence of Mg2+, ADP-ribose transferring activity of poly(ADP-ribose) synthetase was stimulated by the addition of purified endonuclease to the reaction mixture in a dose-dependent manner. Analysis of the reaction product showed that the endonuclease was ADP-ribosylated. The average chain length of the initial oligo(ADP-ribose) attached to the enzyme was about 5.9 residues. The oligomer was found to be extensively elongated during the chase experiment using unlabeled NAD+ and Mg2+. The present finding suggests that Mg2+ is essential for the extensive elongation of the oligo(ADP-ribose). The DNA-binding affinity of the modified endonuclease was significantly lower than that of unmodified enzyme. Also, free poly(ADP-ribose) was not an effective inhibitor of the endonuclease. These findings suggest that the observed inhibition of the endonuclease induced by ADP-ribosylation is probably due to an electrostatic repulsion between the substrate (DNA) and poly(ADP-ribose) covalently linked to the endonuclease. Histone H1 and H2B stimulated endonuclease activity and were acceptors of ADP-ribose; however, their capacity to stimulate endonuclease activity remained unchanged after ADP-ribosylation.

Adenosine Diphosphate Ribose↗
PubMed1984

Forskolin and mouse oocyte maturation in vitro.

Oocytes isolated from mature follicles undergo spontaneous maturation when cultured in vitro. Forskolin, an adenylate cyclase stimulator, inhibited resumption of meiosis of cumulus-free mouse oocytes in vitro. Germinal vesicle breakdown (GVBD) was prevented in more than 85% of the oocytes treated by forskolin at concentrations of 20 micrograms/ml and higher. The inhibiting effect of forskolin was dose-dependent and reversible. FSH, LH, FSH plus LH, estrogen, progesterone, and estrogen plus progesterone did not reverse the block induced by forskolin in cumulus-free and cumulus-enclosed oocytes. The present results suggest that intracellular cAMP may play a role in the regulation of oocyte maturation.

Animals↗
PubMed1984

Mono(adenosine diphosphate ribosyl) transferase in Xenopus tissues. Direct demonstration by a zymographic localization in sodium dodecyl sulfate--polyacrylamide gels.

A semiquantitative method to measure mono(adenosine diphosphate ribosyl) transferase activity [mADPRT] in tissue extracts is described. After electrophoretic separation in sodium dodecyl sulfate (SDS)--polyacrylamide gels, renatured enzymatic activity is demonstrated in situ by incubation of the slab gels with radiolabeled NAD+ and histones. Precipitation of the radiolabeled product in the gel allows localization of the enzyme by autoradiography. This method is suitable for two-dimensional gel electrophoresis, whereby proteins are electrofocused in the presence of 9 M urea and subsequently subjected to electrophoresis in SDS. A single major band showing mADPRT activity of Mr approximately 30 Kda was observed in all crude extracts of Xenopus tissues examined. Accumulation of acid-insoluble radiolabeled products was dependent on added histones and was specifically inhibited by agmatine. The ADPRT activity of cholera toxin A fragment could also be demonstrated by this technique. Reducing agents stimulated the activity of cholera toxin A fragment while depressing that of Xenopus mADPRT.

Animals↗
PubMed1984

Immunolocalization of a sperm membrane protein in human male reproductive organs.

A monoclonal antibody that induces agglutination of human sperm was used to localize the interacting antigen in various tissues by indirect immunofluorescence. The antibody localized to the immature sperm and Sertoli cells of the seminiferous tubules, simple cuboidal epithelial cells of the rete testis, and the columnar epithelial cells of the ductuli efferentes. The present results show that the interacting protein is found associated with germ cells undergoing spermatogenesis.

Animals↗
PubMed1984

A Ca2+-activated channel from Xenopus laevis oocyte membranes reconstituted into planar bilayers.

Plasma membrane fractions from Xenopus laevis oocytes were incorporated into planar lipid bilayers. We show the existence of numerous Ca2+-activated nonspecific channels that are more permeable to anions. These channels are activated by Ca2+ at micromolar concentration but not by Mg2+, Zn2+, or Mn2+, even at millimolar concentrations. Decreasing Ca2+ concentration to less than 1 microM decreases the time of channel opening until channels close completely in the absence of Ca2+ and in the presence of EGTA. I- and Br- are more permeable through this channel than Cl-. The time during which the channels remain open is also voltage-dependent, with the channels switching off at higher voltages in both polarities. Single-channel activity shows a conductance of 380 pS in 1 M NaCl and 1 mM CaCl2, with an average open lifetime of 1.5 s at 40 mV. Similar channels are found in different stages of oocyte maturation. These observations support the hypothesis that an increase in oocyte-free Ca2+ activates directly these channels, and the resultant Cl- efflux forms the ionic basis for the fertilization potential in X. laevis.

Animals↗
PubMed1984

Influence of adenosine 3':5'-cyclic monophosphate analogues on testicular organization of fetal mouse gonads in vitro.

Gonadal primordia, isolated from fetal mice on the 11th or 12th day of gestation, differentiated in vitro into morphologically distinct testes or ovaries after 7 days in culture. The addition of cAMP analogues into culture media prevented the differentiation of testis cords. Histological examination indicated that the basement membranes of testis cords disintegrated after treatment with cAMP analogues, while development of germ cells and Leydig cells appeared to be unaffected. Fetal testes in culture secreted testosterone which increased following addition of dibutyryl-cAMP (Bt2 c-AMP). Primordial germ cells reached prespermatogonial stage in the presence or absence of Bt2 cAMP, suggesting that progressive differentiation of primordial germ cells is independent of testis cord organization. The Bt2 cAMP-treated explants resumed testicular development after transplantation into a site beneath the kidney capsules of adult mice, although the inhibitory effect appeared irreversible in vitro. The testicular organization-preventing effect of cAMP analogues was mimicked by prostaglandins or forskolin, which are known to stimulate adenylate cyclase. The inhibitory effect of either cAMP analogues or prostaglandins was potentiated when added in combination with phosphodiesterase inhibitors. The present results suggest that increase of intracellular cAMP prevents the development of basement membrane and the assembly of cells to form testicular structures.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1984

A factor from bovine granulosa cells preventing oocyte maturation.

A factor preventing spontaneous dissolution of germinal vesicle (GVBD) of mouse oocytes in vitro was isolated from bovine granulosa cells and designated as granulosa cell factor (GCF). Granulosa cells from medium sized (2-5 mm) follicles were suspended in 10 mM Tris-HCl buffer, pH 8.3, containing 1 M urea and 5 mM EDTA. GCF was separated from the extract by gel filtration on Sephadex G-25 column. The molecular weight (Mr) of GCF was estimated to be less than 6,000 daltons. Oocytes treated with GCF and resuspended in control medium resumed GVBD. The partially purified GCF lost GVBD-preventing activity when digested with pronase but retained its activity when treated with DNase, RNase, or glycosidase. GCF was stable to heating at 100 degrees C for 15 min, not absorbed by charcoal, and did not bind to Concanavalin A-Sepharose 4B. The present findings suggest that GCF is a heat-stable polypeptide and its action is reversible.

Animals↗
PubMed1984

Induction of testicular differentiation in the fetal mouse ovary by transplantation into adult male mice.

Mouse ovarian primordia on the 12th or 13th day of gestation frequently developed testicular structures in addition to ovarian structures by the 14th day after transplantation into a site beneath the kidney capsules of adult male mice. Electron microscopic examination of the testicular portion of ovotestes revealed all types of testicular somatic cells, i.e., Sertoli, myoid, and Leydig cells, but not spermatogenic cells. On the other hand, after transplantation into adult female mice ovarian grafts developed only ovarian structures. We conclude that female gonadal somatic cells differentiate into testicular components in a male host environment.

Animals↗
PubMed1983

Xenopus mono(adenosine diphosphate ribosyl) transferase: purification, assay, and properties.

Various tissues of Xenopus laevis possess mono(ADP-ribosyl) transferase activity. The Xenopus liver enzyme was purified approximately 40,000-fold by sequential chromatography on phenyl Sepharose, DEAE-Sephadex, NAD+-Agarose, and Con A-Sepharose. The enzyme is relatively heat-stable, has no cation requirements, transfers monomers of ADP-ribose from NAD+ to arginine-rich histones H3 and H4, and is not dependent upon DNA for activity. Its Mr was estimated to be 30 kilodaltons (KD). The amino acid acceptor of the ADP-ribose moiety is probably arginine, and the bond formed is resistant to the hydrolytic action of neutral hydroxylamine. The transferase activity was neither inhibited nor precipitated by antisera directed against the A fragment of cholera or diphtheria toxins. Theophylline, thymidine, nicotinamide, and some of its analogues blocked the enzymatic activity, while nicotinic acid was ineffective. When a DNA-free extract of HeLa cells was incubated with the transferase system, several proteins were found to be ADP-ribosylated. A band at position 90 KD showed high specific radioactivity. A zymographic method for assaying transferase activity in crude tissue extracts was developed. In the initial step, the extracts were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Using this method, a histone-dependent mono(ADP-ribosyl) transferase corresponding to an Mr of about 30 KD was demonstrated in every tissue examined. Treatment with reducing agents practically abolished transferase activity in contrast to the enhancement of choleragen A fragment activity. A variant of the transferase at about 80 KD was detected. It differed from the 30 KD enzyme in that histones inhibited its activity while agmatine had no influence.

ADP Ribose Transferases↗
PubMed1983

DNA interference with radioimmunoassay procedures.

A bacterial factor preventing precipitation of immune complexes was purified from a culture of Streptococcus faecalis (AK strain) by gel filtration on Sephadex G-100 and Bio-Gel A-150m columns. The factor was identified as DNA on the basis of its ultraviolet absorption maximum at 260 nm, hydrolysis by deoxyribonuclease, Mr exceeding 1.5 X 10(8), and positive reaction with diphenylamine. DNA interferes with the immunoassay by preventing precipitation of immune complexes. Only double-stranded DNA and polynucleotides showed this property. Evidently, double-stranded DNA will give false-positive interference with the usual RIA procedures.

Antigen-Antibody Complex↗