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Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 379 records · Page 21Linked to original sources
PubMed1991

Evidence for the endogenous GTP-dependent ADP-ribosylation of the alpha-subunit of the stimulatory guanyl-nucleotide-binding protein concomitant with an increase in basal adenylyl cyclase activity in chicken spleen cell membrane.

We investigated the endogenous GTP-dependent ADP-ribosylation of the alpha-subunit of the stimulatory guanyl-nucleotide-binding protein (Gs alpha) concomitant with an increase of basal adenylyl cyclase activity in chicken spleen cell membranes. When these membranes were incubated with [adenylate-32P]NAD, there was significant incorporation of [32P]ADP-ribose into a 45-kDa acceptor protein in the membranes. This reaction was inhibited when 20 mM arginine was present during the incubation. When the membranes were incubated with unlabelled NAD, subsequent ADP ribosylation by cholera toxin was diminished significantly. Thus, chicken spleen cell membranes have the potential to endogenously ADP-ribosylate the arginine residue of Gs alpha. The endogenous ADP-ribosylation Gs alpha was enhanced by the addition of 0.1 mM GTP or 0.1 mM guanosine 5'-[gamma-thio]triphosphate (GTP[S]), but not 0.1 mM GDP, 0.1 mM ATP or 0.1 mM ADP. The endogenous GTP-dependent ADP-ribosylation of Gs alpha stimulated basal adenylyl cyclase activity. Furthermore, NAD-induced stimulation of basal adenylyl cyclase activity was suppressed, when the membranes were incubated with NAD in the presence of novobiocin, an inhibitor of arginine-specific ADP-ribosyltransferase. These data represent the first demonstration that a eukaryotic cell membrane contains an ADP-ribosyltransferase which can catalyze the endogenous GTP-dependent ADP-ribosylation of the arginine residue of Gs alpha and that this modification enhances basal adenylyl cyclase activity in the membrane. In light of this evidence, the possible control of basal adenylyl cyclase activity via endogenous GTP-dependent ADP-ribosylation in eukaryotic cells warrants further attention.

Adenosine Diphosphate Ribose↗
PubMed1991

Comprehensive treatment of bilateral cleft lip by multidisciplinary team approach.

Repair of bilateral cleft lip presents numerous problems, and in our opinion, it is better to begin treatment at the earliest age possible. At Fujita Health University Hospital, we utilise a multidisciplinary team approach to cleft lip. Nonsurgical correction of the nasal deformity using a nose retainer and preoperative orthodontics using a Kuwahara-modified Hotz's palatal plate begins soon after birth. Surgical repair of the lip is done within the first 2 months of life, by the time the nose, alveolus and projecting prolabium are adequately reformed. A one-stage surgical procedure, including restoration of muscle union, labial sulcus construction and nasal correction is performed. After lip repair, lip and tongue pressure are well balanced by the plate, and a good alignment of the alveolus can be achieved. A total of 27 cases of bilateral cleft lip were treated from August 1986 to October 1990. In all cases, the postoperative course was uneventful, and no complications due to early surgery were encountered.

Cleft Lip↗
PubMed1991

Cyclic adenosine monophosphate promotes the proliferation of chicken granulosa cells in culture.

The aim of this study was to determine if cAMP regulates the proliferation of chicken granulosa cells and if there is a difference in the effects of cAMP on the granulosa cell proliferation between the largest follicle (F1) and the smaller follicles. Granulosa cells collected from F1 and the third largest follicle (F3) were cultured in medium M199 containing 1% calf serum with or without dibutyryl cAMP (dbcAMP). Proliferation of granulosa cells of F1 was promoted by dbcAMP in a dose-dependent manner. The most effective concentration of dbcAMP to promote the granulosa cell proliferation was 2 mM. In the culture without dbcAMP, the number of the granulosa cells was not changed significantly for 6 days, whereas, in the presence of 2 mM dbcAMP, the number of the granulosa cells was markedly increased during 2 to 6 days. The proliferation of the granulosa cells of F3 was stimulated by dbcAMP in the same manner as that of F1. Morphologically, the granulosa cells of F1 and F3 cultured for 2 days had a sheet-like appearance in control culture, whereas they were contracted, leaving finger-like cytoplasmic processes attached to the adjacent cells and substratum in the presence of 2 mM dbcAMP. After 6 days culture, approximately 90% of the cells of F1 stained positive for 3 beta-hydroxysteroid dehydrogenase activity in 2 mM dbcAMP-containing culture, whereas only about 20% of the cells were positive in control culture. These results suggest that cAMP promotes the proliferation of the granulosa cells during the follicular growth and this response of granulosa cells to cAMP is similar for F1 and F3.

Animals↗
PubMed1991

Gonadotropin-releasing hormone agonists induce meiotic maturation and degeneration of oocytes in the in vitro perfused rabbit ovary.

The present study was undertaken to assess the effects of gonadotropin-releasing hormone agonists (GnRH-a, buserelin and leuprolide acetate [LA]) on ovulation, oocyte maturation and degeneration, and steroid and prostaglandin production in the perfused rabbit ovary preparation. Ovulation did not occur in any of ovaries treated with buserelin or LA (10(2) to 10(4) ng/mL) in the absence of gonadotropin. Gonadotropin-releasing hormone agonists were associated with the resumption of meiosis in follicular oocytes in a dose-related manner. Furthermore, the addition of GnRH-a to the perfusate significantly increased the percentage of follicular oocytes that showed evidence of degeneration compared with contralateral untreated or human chorionic gonadotropin-treated controls. Prostaglandin E2 and prostaglandin F2 alpha production by the perfused rabbit ovaries were stimulated significantly by GnRH-a treatment. Exposure to GnRH-a failed to increase either progesterone or estradiol production by the perfused rabbit ovaries. These data demonstrate that GnRH-a act directly in the rabbit ovary to trigger meiotic maturation in oocytes within the follicles, concomitantly increasing oocyte degeneration.

Animals↗
PubMed1991

Treatment of uterine leiomyomata with a luteinizing hormone-releasing hormone agonist: the possibility of nonsurgical management in selected perimenopausal women.

OBJECTIVE: To evaluate the efficacy of luteinizing hormone-releasing hormone agonist (LH-RH-a) in the treatment of leiomyomata. DESIGN: A retrospective randomized trial. SETTING: Hospital department of obstetrics and gynecology. PATIENTS: Twenty-five women, ages 36 to 54 years with symptomatic uterine leiomyomata, were divided into two groups according to the responsiveness to LH-RH-a: group A patients reached menopause after LH-RH-a, whereas resumption of menstruation occurred within 12 weeks after cessation of therapy in group B. INTERVENTIONS: Luteinizing hormone-releasing hormone agonist was administered intranasally three times a day with 150 micrograms insufflation of one spray in each nostril (total dose: 900 micrograms/d). MAIN OUTCOME MEASURES: Efficacies of treatment were assessed in terms of uterine volume, hemoglobin concentrations, serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and bone density during and after treatment. RESULTS: In both groups, hemoglobin concentrations increased significantly after 16 weeks of treatment. A significant reduction in uterine volume was observed in both groups. After completing therapy, there was no further significant change in uterine volume in group A, whereas uterine volume in group B returned to pretreatment values. Serum LH and FSH concentrations were suppressed during treatment, but those gonadotropins in group A increased significantly up to the menopausal levels after treatment. Serum E2 concentrations in both groups showed consistent suppression by the end of the first treatment cycle. After cessation of therapy, serum E2 levels on group A remained in the castrate range, whereas E2 in group B returned to pretreatment levels, concomitant with the return of normal ovulation. CONCLUSIONS: Intranasal administration of LH-RH-a was successful in significantly decreasing uterine volume and increasing hemoglobin concentration in premenopausal women with leiomyomata.

Adult↗
PubMed1991

Androstenedione and progesterone concentrations in preovulatory follicular fluid correlate with successful fertilization and cleavage of human oocytes in vitro.

OBJECTIVE: To determine if androstenedione (A) and progesterone (P) concentrations in preovulatory follicular fluid (FF) correlate with successful fertilization and cleavage of human oocytes in vitro. DESIGN: A retrospective randomized trial. SETTING: Hospital department of obstetrics and gynecology. PATIENTS: Fifty-five patients, ages 24 to 39 years, with normal menstrual cycles undergoing in vitro fertilization (IVF) for tubal infertility. INTERVENTIONS: Multiple follicular development was induced with clomiphene citrate and human menopausal gonadotropin. MAIN OUTCOME MEASURES: Relationships among FF steroid hormone, morphological maturity of oocyte-corona-cumulus complexes, and fertilization and cleavage of oocytes. RESULTS: Follicles with mature oocyte-corona-cumulus complexes and unfertilized oocytes contained significantly greater amounts of A (P less than 0.05) than those with mature oocyte-corona-cumulus complexes and fertilized ova, indicating the occurrence of atretic changes. Follicles yielding successfully fertilized and cleaved ova had significantly greater amounts of P (P less than 0.05) and A (P less than 0.01) but similar levels of 17 beta-estradiol compared with follicles yielding fertilized ova that failed to cleave. CONCLUSIONS: Follicles yielding oocytes that cleaved as a result of IVF have both a shift in steroidogenesis from estrogen to progestin accumulation and declining aromatase activity, thus reflecting progressive luteinization of the follicles.

Adult↗
PubMed1991

Input-specific induction of long-term depression in Ca(2+)-chelated visual cortex neurons.

An input-dependent increase in postsynaptic Ca2+ may play a role in long-term potentiation (LTP) of synaptic transmission while no or subthreshold increase in Ca2+ is associated with long-term depression (LTD) in the developing visual cortex. To see whether LTD is induced only at tetanized synapses, a Ca(2+)-chelator was injected into layer 2/3 neurons in cortical slices from young rats, and excitatory postsynaptic potentials (EPSPs) of these cells, after test stimulation of the white matter and layer 1/2, were observed before and after tetanic stimulation of the former site. The chelator injection led to LTD of EPSPs at tetanized synapses, but no changes were seen at non-tetanized synapses. These results suggest that tetanic inputs induce LTD at tetanized synapses when they are associated with no or subtle increase in postsynaptic Ca2+.

Animals↗
PubMed1991

One-stage repair of blepharophimosis.

Congenital blepharophimosis is a congenital anomaly characterized by abnormalities in the area of the eyes, including bilateral ptosis, shortening of the horizontal fissure of the lid, expansion of the intercanthal distance, and epicanthus inversus. The condition is subject to autosomal-dominant heredity and is said to occur more frequently in Orientals than in Occidentals. Over the past 9 years, we have surgically treated 11 cases of congenital blepharophimosis using a procedure in which levator resection and medial canthoplasty are performed in one stage. It has been commonly believed that when levator resection and medial canthoplasty are performed at the same time, tension in the eyelid becomes too strong to achieve favorable results; therefore, the standard procedure has been to divide the operation into two stages. In all 11 cases we experienced, however, it was possible to obtain good results with a single-stage operation.

Child, Preschool↗
PubMed1991

Reconstruction of the entire upper eyelid area with a subcutaneous pedicle flap based on the orbicularis oculi muscle.

Lagophthalmos caused by trauma or inflammation may damage the cornea and, if not adequately treated, may result in loss of eyesight. Hence surgical intervention is required at the earliest possible stage. We have developed a subcutaneous pedicle flap elevated from the temporozygomatic area and rotated 180 degrees around a small pedicle base that contains the orbicularis oculi muscle. With this flap, the entire upper eyelid can be reconstructed as an aesthetic unit in one stage so that the result is satisfactory not only functionally, but also cosmetically. The operative procedure is presented along with case reports.

Adult↗
PubMed1991

Treatment effects of GnRH agonist on the binding of estrogen and progesterone, and the histological findings of uterine leiomyomas.

The changes in the histology and steroid hormone binding capacity of the uterine leiomyomas treated with; GnRH agonists (GnRHa buserelin acetate in, 900 micrograms/day for 16 weeks) were investigated. The occurrence of hyaline degeneration in the myometrium was significantly higher in the GnRHa-treated group than in the control group, and the grade of hyaline degeneration was more advanced in the GnRHa group. After the GnRHa treatment, the Bmax of the estrogen receptor increased significantly in the leiomyomas and myometrium. The Bmax of progesterone receptors in the myometrium decreased significantly and the reduction rates of leiomyomas (% of the initial volumes) measured by MRI correlated (r = 0.775) with the Bmax of progesterone receptors. In summary, GnRHa caused hyaline degeneration of the uterine leiomyomas which were responsible for the shrinkage. The shrunk leiomyomas have the potential for regrowth in response to estrogen as they still have high concentrations of the estrogen receptors.

Adult↗
PubMed1991

Effect of bupivacaine on muscle tissues and new bone formation induced by demineralized bone matrix gelatin.

Heterotopic bone formation induced by demineralized bone matrix gelatin (BMG) in bupivacaine-HCl-treated skeletal muscle was examined histologically. BMG was obtained by dehydrating diaphyseal shafts of femora and tibiae of male, 4-week-old Sprague-Dawley (SD) rats, cutting it into chips, and demineralizing and extracting the chips with various solutions. The BMG was implanted into the rectus abdominis muscle of male, 5-week-old SD rats, bupivacaine-HCl was injected at the same site, and the resulting plaques of tissues were examined histologically on days 5, 10, 15 and 20 after BMG implantation. Heterotopic bone formation occurred in all animals. The bupivacaine-treated group had more degenerated and injured muscle fibers, and more osteocytes than the control group. Electron microscopy showed that the basement membrane of muscle fibers was discontinuous and that many mononucleated cells resembling activated satellite cells were present on day 5. Many fibroblasts, undifferentiated mesenchymal cells and myogenic cells were seen in the area around the BMG. In new bones there were few osteocytes on day 10, but their numbers were increased on days 15 and 20 after implantation, especially in the bupivacaine-treated group. The population of osteocytes that increased rapidly may have included mononucleated cells similar to activated satellite cells.

Abdominal Muscles↗
PubMed1991

Possible contribution of prolactin in the process of ovulation and oocyte maturation.

The present study was undertaken to evaluate the effects of PRL in the process of ovulation and oocyte maturation. In the first experiment, using an in vitro perfused rabbit ovary model, the addition of PRL to the perfusate inhibited hCG-induced ovulation in a dose-related fashion, without any reduction in progesterone synthesis. In a subsequent experiment, PRL directly inhibited both the degeneration and decomposition of surface epithelial cells and the disruption of connective tissue at the apex of the follicle wall. Furthermore, PRL inhibited hCG-stimulated plasminogen activator (PA) activity in mature follicles in a dose-related fashion. In the final experiment, we demonstrated conditions in which rabbit oocytes matured in vitro acquire competence for early embryonic development. PRL, as well as gonadotropins and estradiol, was an important constituent in the process of oocyte maturation, promoting embryonic development. These results suggest that the preovulatory environment of PRL within the follicle may influence the process of ovulation and oocyte maturation.

Animals↗
PubMed1991

Effects of prolactin on fertilization and cleavage of human oocytes.

The effects of PRL on fertilization and cleavage of human oocytes and subsequent pregnancy were studied. Forty-five patients (47 cycles) with euprolactinemic normal menstrual cycles undergoing in vitro fertilization (IVF) for the treatment of tubal infertility were selected for this study. The patients were divided into three groups dependent upon their mean serum PRL concentrations for the 3 days prior to oocyte retrieval; hypoprolactinemic (less than 10 micrograms/l), euprolactinemic (10-30 micrograms/l) and hyperprolactinemic cycles (greater than or equal to 30 micrograms/l). Multiple follicular development was induced with hMG, and 10 patients were randomized to receive bromocriptine beginning with the previous menstrual cycle. In the hypoprolactinemic cycle group, the fertilization rate was significantly lower than in the hyperprolactinemic cycle group, and the cleavage rate was significantly lower than in the other groups. The fertilization rates and the cleavage rates in the hyperprolactinemic cycle group were higher than those in the euprolactinemic cycle group; however, these differences were not statistically significant. While the pregnancy rates in the euprolactinemic cycle group were higher than in the other two groups, the numbers were too small for meaningful statistical comparison. The present study demonstrates that below normal concentrations of PRL have deleterious effects on IVF outcome. These data suggest that PRL may play a beneficial stimulatory role in oocyte maturation and the acquisition of developmental capacity.

Adult↗
PubMed1991

Localization of progesterone receptors in pre- and postovulatory follicles of the domestic hen.

Progesterone may act locally to modulate follicular maturation and ovulation in the domestic hen. The distribution of progesterone receptors (PR) in the pre- and postovulatory follicles was determined in hens by immunocytochemistry and Western blot analysis. Monoclonal antibodies to chicken PR, PR6, and PR 13, were used. PR were localized in nuclei of theca externa fibroblasts and germinal epithelial cells in stigma and nonstigma regions of the third largest preovulatory follicle (F3). In the largest preovulatory follicle (F1), PR were present in theca externa fibroblasts, germinal epithelial cells, and also in granulosa cells and some of the theca interna fibroblasts in the stigma and nonstigma region. Twenty-four hours after ovulation, PR in the fibroblasts of the theca externa of the postovulatory follicle (POF) were remarkably reduced, but the amount of PR in the granulosa cells was similar to that observed in the F1. A high density of PR was also found in the fibroblasts, arterial wall, and smooth muscle fibers in the loose connective tissue of pre- and postovulatory follicles. Western blot analysis indicated that PR in the granulosa and theca tissue were identical in molecular weight to PR in the shell gland. Western blot analysis also confirmed the changes in the amounts of PR in the pre- and postovulatory follicles as determined by immunocytochemistry. The relative amounts of PR in the granulosa cells as determined by Western blot analysis was F2 less than F1 = POF, and in theca tissue was F2 = F1 greater than POF. The presence of PR in specific ovarian tissues suggests that these tissues are target tissues for progesterone and that progesterone may have a role in regulating follicular maturation and ovulation through receptor-mediated pathways.

Animals↗