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Biomedical subjects

Y X Liu

Publications and source records attributed to Y X Liu.

At least 109 records · Page 6Linked to original sources
PubMed1989

A factor from granulosa cells can stimulate oocyte tissue plasminogen activator activity.

Several studies indicate that substances synthesized by granulosa cells are capable of regulating oocyte activity. We have studied the effect of factors synthesized by granulosa cells on tPA activity of denuded oocytes using a co-culture system. The results show that an FSH-dependent factor(s) synthesized by granulosa cells (but not by theca-interstitial cells) is capable of stimulating tPA activity of denuded oocytes. This finding is important for understanding hormonal regulation of oocyte tPA activity by mediators synthesized in granulosa cells.

Animals↗
PubMed1989

[CT myelography with low concentration and/or a low dose of nonionic contrast water-soluble medium].

This paper presented the results of CT myelography with a low concentration and/or low dose of nonionic contrast water-solvable medium was used for 170 patients. The results had shown that the micro-structure within the spinal canal was shown clearly, the quality of film screen images were good, the interval between the time of injection and that of scanning was shortened, the scope of plain CT was widened, and its diagnostic accuracy was high. The side effects did occur infrequently and were usually mild in nature.

Adolescent↗
PubMed1989

[Biochemistry of neonatal cord blood following intrapartum glucose and oxytocin infusion].

The effect of intrapartum glucose and oxytocin infusion on the biochemical values of umbilical cord blood including Na, K, Cl, Ca, P, glucose, BUN and osmolality was studied in 246 newborns. The newborns were divided into 4 groups: Group 1 consisted of 162 babies whose mothers did not receive any intravenous infusion. Group 2. 53 babies, Group 3. 16 babies and Group 4.15 babies whose mothers received infusion of oxytocin in glucose (5U/L). The total amounts of infusion were less than 500 ml in Group 2. 500ml in Group 3. 500-1,000 ml in Group 4. Group 3 were delivered with forceps. In comparison with Group 1, the serum K+ in Group 2 and Cl- values in Group 4 were lower while the glucose values were higher in Groups 2, 3 and 4 (highest in Group 3). The other values were not significantly different.

Blood Glucose↗
PubMed1988

Gonadotropin-releasing hormone induces ovulation in hypophysectomized rats: studies on ovarian tissue-type plasminogen activator activity, messenger ribonucleic acid content, and cellular localization.

GnRH and its agonists are known to induce ovulation in hypophysectomized rats by acting directly at the ovary. Because tissue-type plasminogen activator (tPA) has been implicated in the gonadotropin induction of ovulation, we examined the effect of an ovulatory dose of GnRH on ovarian tPA activity, mRNA content, and cellular localization. Hypophysectomized immature rats were injected sc with 20 IU PMSG and a single dose of a GnRH agonist (GnRHa; des-Gly10,DLeu6(N alpha Me)Leu7,Pro9NHEt-GnRH) 58 h later. At different times after treatment, ovaries were prepared for morphological analysis. Using a fibrin overlay method, tPA activities were measured in ovarian homogenates and cumulus-oocyte complexes, whereas granulosa cells were cultured for 24 h to estimate tPA secretion. Total ovarian RNA was prepared for hybridization analysis of tPA message levels, and tPA localization was studied by immunohistochemistry of ovarian sections. GnRHa induced ovulation in PMSG-primed hypophysectomized rats 14-16 h after injection in a dose-dependent manner, and the GnRHa action was blocked by concomitant treatment with a GnRH antagonist. GnRHa stimulated the induction of tPA, but not urokinase-type PA, activity in ovarian homogenates and granulosa cell-conditioned medium in a time-dependent manner, reaching a maximum before ovulation. tPA activity in cumulus-oocyte complexes was also increased before ovulation, but this increase was sustained. Hybridization analysis of steady state tPA mRNA levels was performed using a rat cRNA probe. Northern blot analysis of total ovarian RNA demonstrated that GnRHa stimulated tPA mRNA levels 12 h after treatment, with a subsequent decrease 24 h after treatment. Immunohistochemistry indicated substantial increases in tPA staining in granulosa cells and oocytes of preovulatory follicles before ovulation. Thus, GnRHa acts through specific receptors to increase ovarian tPA enzyme activity, mRNA content, as well as immunostaining in granulosa cells and oocytes. Like gonadotropins, GnRH may induce ovulation by directly stimulating tPA levels in the ovary.

Animals↗
PubMed1988

Indomethacin inhibits hCG and GnRH agonist-induced secretion of plasminogen activator by granulosa and theca interstitial cells of hypophysectomized rats.

Considerable data have shown that plasminogen activator (PA) may play an important role in the mechanism of ovulation. A recent report argued that PA is not a primary proteolytic enzyme for follicular rupture because a dose of indomethacin that blocked ovulation did not inhibit ovarian PA content. To further clarify the specific role of PA in the ovulation, we have carefully examined the effect of indomethacin on the secretion of PA in granulosa and theca-interstitial (TI) cells following hCG or GnRH agonist administration in PMSG-primed hypophysectomized immature rats. We have also studies in vitro action of this compound on PA secretion in granulosa cells. The results indicate that indomethacin can only suppress hCG- and GnRH agonist-induced PA secretion, but not suppress the ovarian content of these enzymes.

Animals↗
PubMed1988

Interaction and regulation of plasminogen activators and their inhibitor in rat follicles during periovulatory periods.

Ovarian follicles produce two types of plasminogen activator (tPA and uPA), and their inhibitor (PAI). We have examined the interaction and regulation of these factors in ovarian intact follicles as well as granulosa and theca-interstitial cells. The results show that only tPA, but not uPA, is regulated by the gonadotropins and reaches maximum prior to ovulation. PAI is secreted mainly by theca-interstitial cells and is stimulated also by the gonadotropins. The formation of complexes between PA and PAI completely blocks or decreases PA activity. It is suggested that the interaction between plasminogen activators and their inhibitor in the follicles may play a very important role in maintaining normal ovarian function and the machnism of ovulation.

Animals↗
PubMed1988

A factor(s) produced by Sertoli cells stimulates androgen biosynthesis by Leydig cells in neonatal rats.

Using a coculture system, we have studied the local action of Sertoli cells on Leydig cell function. The results show that (i) both LH and FSH have equal potency to stimulate testosterone biosynthesis by fetal and neonatal testicular cells in an age-dependent manner, the maximum stimulation is observed between D3 and D5. (ii) An FSH-dependent factor(s) secreted by Sertoli cells increases the basal and/or LH-stimulated Leydig cell androgen production. (iii) The Sertoli cell-stimulating factor(s) is not a steroid or other small molecule, but a heat-labile peptide.

Animals↗
PubMed1987

Effects of some alcohols on the conformation of mitochondrial H+-ATPase complex and F1-ATPase from pig heart.

The conformations of the H+-ATPase complex and F1-ATPase in low concentrations of methanol, ethanol, n-propanol, iso-propanol and t-butanol were studied by circular dichroism. For F1-ATPase, all but methanol first increased and then decreased the circular dichroism magnitude of helical bands as the alcohol concentration was increased. With ethanol, n-propanol, iso-propanol and t-butanol, the alpha-helix content reached a maximum at about 5% alcohol and began to decrease at 10%. The content of beta-sheet showed the opposite effect, reaching a minimum at 5% and increasing slightly at higher concentrations. None of the alcohols studied had a significant effect on the conformation of the H+-ATPase complex. This difference implies that the alcohols had a greater effect on free F1-ATPase than on the membrane-bound F1-ATPase. The hydrophobic protein F0 and the membrane lipids in the H+-ATPase complex may stabilize and protect F1 from the effects of the alcohols.

1-Propanol↗
PubMed1987

Regulation of tissue-type plasminogen activator activity and messenger RNA levels by gonadotropin-releasing hormone in cultured rat granulosa cells and cumulus-oocyte complexes.

Gonadotropin-releasing hormone (GnRH) acts directly on the ovary to induce ovulation in hypophysectomized proestrous rats. Because plasminogen activators (PAs) are implicated in gonadotropin-induced ovulation, we have studied the effect of GnRH on ovarian PA synthesis. GnRH induced tissue-type PA (tPA) secretion by cultured rat granulosa cells, but inhibited the secretion of urokinase-type PA. These effects were blocked by co-treatment with a GnRH antagonist, suggesting that stereospecific GnRH receptors are involved. Follicle-stimulating hormone (FSH) also induced tPA in granulosa cells but with a different time course than GnRH; the combined effect of FSH and GnRH was additive. The GnRH effect was mimicked by the calcium- and phospholipid-dependent protein kinase C activator, phorbol myristate acetate. In isolated cumulus-oocyte complexes and cumulus cells, GnRH treatment also increased tPA activity. In contrast, treatment of denuded oocytes with GnRH did not increase enzyme activity. After GnRH stimulation of the cumulus-oocyte complexes, tPA content in the denuded oocyte was elevated, suggesting that the cumulus cells mediate the action of GnRH to increase the oocyte enzyme levels. Hybridization experiments using a labeled rat tPA-specific DNA probe showed that both FSH and GnRH increased the level of tPA mRNA in cultured granulosa cells; the stimulatory effect of GnRH was blocked by the GnRH antagonist. Our results indicate that GnRH treatment increases tPA secretion by cultured granulosa cells and cumulus-oocyte complexes. The stimulation of enzyme activity in the granulosa cells is accompanied by increases in tPA mRNA levels.

Animals↗
PubMed1987

Congenital esophageal stenosis due to tracheobronchial cartilage.

Six cases of lower esophageal stenosis due to tracheo-bronchial remnants are reported. The symptoms become apparent after weaning. Esophagography and esophagoscopy are the essential means for diagnosis. The treatment includes resections of the stenotic segment and an end-to-end anastomosis.

Bronchi↗
PubMed1987

Gonadotropin regulation of tissue-type and urokinase-type plasminogen activators in rat granulosa and theca-interstitial cells during the periovulatory period.

Plasminogen activators (PAs) are believed to be involved in ovulation. Because both tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) are secreted by cultured rat granulosa cells, we have examined the activities of these proteins in ovarian homogenates as well as granulosa and theca-interstitial (TI) cells during gonadotropin-induced ovulation. Immature rats were injected with 20 IU pregnant mare serum gonadotropin (PMSG) to initiate follicle development, followed by treatment with 10 IU hCG 48 h later to induce ovulation. Ovarian proteins were separated by SDS-PAGE and PA activity determined by fibrin overlay. The activity of tPA, but not uPA, was stimulated following PMSG treatment in ovarian homogenates. Subsequent hCG injection further increased the tPA activity in a time-dependent manner, reaching a maximum (12 h after hCG treatment) immediately prior to ovulation and declined thereafter. Similar preovulatory increases in tPA activity were detected in isolated granulosa cells. Although both tPA and uPA activities were increased in TI cells after PMSG administration, no further increases were detected after hCG treatment. To estimate enzyme secretion, ovarian cells obtained at various preovulatory periods were incubated for 24 h in vitro. The ability of granulosa cells to secrete tPA, but not uPA, increased following in vivo PMSG and hCG treatment in a time-dependent manner, reaching a maximum immediately prior to ovulation. During the preovulatory period, an abrupt increase in tPA secretion by TI cells was also detected. Using immunohistochemical staining for tPA, it was found that ovarian sections from preovulatory rats at 12 h after hCG injection stained positively in granulosa, theca interna, and interstitial gland cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Plasminogen activator activity in cumulus-oocyte complexes of gonadotropin-treated rats during the periovulatory period.

Two types of plasminogen activator (tissue-type, tPA; urokinase-type, uPA) have been demonstrated in ovarian granulosa cells, but only tPA activity was found in denuded oocytes. Immature rats were treated subcutaneously with 20 IU pregnant mare's serum gonadotropin (PMSG) to stimulate follicle maturation, followed 2 days later by an injection of 10 IU human chorionic gonadotropin (hCG) to induce ovulation. Cellular plasminogen activator activities were determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis followed by a fibrin-overlay technique. Cumulus-oocyte complexes from rats before and after PMSG treatment contained low amounts of tPA, but not uPA, activity. After hCG treatment, tPA activity showed a time-dependent increase, reaching a maximum at 24 h after injection. At 12 and 24 h after hCG treatment, uPA activity was also detected. The appearance of high molecular weight lysis zones further suggested the formation of plasminogen activator-inhibitor complexes. Morphological analysis indicated that the increases in oocyte tPA activity were correlated with the extent of cumulus cell expansion and dispersion. In denuded oocytes, tPA activity also progressively increased during the periovulatory period to a maximum at 24 h after hCG treatment. In contrast, neither uPA activity nor activator-inhibitor complex was detected. Secretion of the proteases was measured in the conditioned media of cumulus-oocyte complexes cultured for 24 h in vitro. Substantial increases in tPA release were found in complexes obtained at 8 and 12 h after hCG injection, with lower secretion from complexes obtained at 24 h after hCG treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗