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Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 37 records · Page 2Linked to original sources
PubMed1992

Induction of meiotic maturation of follicle-enclosed oocytes of rabbits by a transient increase followed by an abrupt decrease in cyclic AMP concentration.

The involvement of cyclic adenosine monophosphate (cAMP) in mammalian oocyte maturation was assessed using cultures of rabbit cumulus-oocyte complexes and perfused rabbit ovaries. Rabbit cumulus-oocyte complexes were cultured in Brackett's medium with or without forskolin at 10(-4), 10(-5) or 10(-6) mol l-1 for 3-6 h. At 3 or 4 h spontaneous meiotic maturation was significantly (P < 0.05) inhibited by forskolin at 10(-4) mol l-1. With prolonged incubation, spontaneous maturation progressed despite exposure to forskolin. In the second experiment ovaries were perfused for 12 h with forskolin (10(-4), 10(-5) or 10(-6) mol l-1) or medium alone. Neither ovulation nor degeneration of follicular oocytes occurred in any perfused ovary. The percentage of follicular oocytes achieving germinal vesicle breakdown was significantly (P < 0.001) increased in response to forskolin in a dose-related manner. In an additional experiment, ovaries were perfused with forskolin at 10(-4) mol l-1. A significant increase in the cAMP content in the follicle was observed within 30 min, but the ability to produce cAMP in response to forskolin decreased as the duration of perfusion was increased. Intraoocyte cAMP increased significantly within 30 min and reached its maximum 2 h after exposure to forskolin. Thereafter, cAMP levels in the oocytes decreased abruptly. This drop in intraoocyte cAMP concentration was followed by the resumption of meiosis. The alterations of intraoocyte cAMP contents following exposure to hCG in vivo paralleled those observed in the ovaries perfused with forskolin. These data suggest that a transient, but not continuous, increase in cAMP concentration after the gonadotrophin surge may be required to initiate oocyte maturation.

Animals↗
PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. III. Synthesis and antibacterial activity of 7 beta-[2-(2-amino-5-substituted-thiazol-4-yl)-2 (Z)-alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl-3-cephem-4- carboxylates.

As a part of our research on the synthesis of cephalosporins bearing condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus, we describe herein the synthesis of 7 beta-[2-(2-amino-5-halogeno-, methylthio-, methylsulfinyl-, methylsulfonyl- and sulfothiazol-4-yl)-2(Z)-alkoxyiminoacetamido] cephalosporins and their antibacterial activity. Among the compounds prepared, 7 beta-[2-(2-amino-5-chlorothiazol-4-yl)-2(Z)- methoxyiminoacetamido]-3-(imidazo[1,5-a]-pyridinium-1-yl)methyl-3-cephem -4-carboxylate (14) showed good antibacterial activity against both Staphylococcus aureus including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, whereas the antibacterial activity against other Gram-negative bacteria was a slightly lower than that of 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(im ida zo [1,2-a]pyridinium (I-1) and imidazo[1,5-a]pyridinium (I-4)-1-yl)methyl-3-cephem-4-carboxylates.

Anti-Bacterial Agents↗
PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. IV. Synthesis and antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)- alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl cephalosporins including SCE-2787.

The synthesis and in vitro antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-alkoxyiminoacetami do] cephalosporins bearing various condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus are described. The thiadiazolyl cephalosporins showed good antibacterial activity against both Gram-positive and Gram-negative bacteria and the MICs of the thiadiazolyl cephalosporins against Pseudomonas aeruginosa was more potent than that of the corresponding 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]-3- (condensed-heterocyclic azolium)methyl cephalosporins. Also, the thiadiazolyl cephalosporins bearing (imidazo[1,2-b]-pyridazinium-1-yl)methyl groups at the 3 position showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Among the cephalosporins tested, 7 beta-[2-(5- amino-1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetamido]-3-(imidaz o[1,2- b]pyridazinium-1-yl)methyl-3- cephem-4-carboxylate (4, SCE-2787) which exhibited the most potent antibacterial activity and the broadest antibacterial spectrum was selected as a parenteral cephalosporin candidate for further biological evaluation.

Cephalosporins↗
PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. V. Synthesis and antibacterial activity of 3-(condensed-triazolo-pyridinium, -pyrimidinium, and -pyridazinium)-methyl cephalosporins.

As a part of our studies on cephalosporins bearing condensed-heterocyclic azolium methyl groups at the 3 position in the cephalosporin nucleus, we describe here the synthesis and antibacterial activity of 7 beta-[2-(2-aminothiazol-4-yl)2(Z)-methoxyiminoacetamido] cephalosporins (1-16, 7 beta-[2-(2-amino-5-chlorothiazol-4-yl)-2(Z)- methoxyiminoacetamido] cephalosporins (17,18) and 7 beta-[2-(5-amino- 1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetamido) cephalosporins (19-23) containing a variety of condensed-heterocyclic triazolium methyl groups at the 3 position in the cephalosporin nucleus. These cephalosporins exhibited potent antibacterial activity, and it appears that condensed-heterocyclic triazolium as well as condensed-heterocyclic imidazolium rings are effective moieties for improving antibacterial activity and the spectrum of activity. Among the cephalosporins tested, 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(5- methyl[1,2,3]triazolo-[1,5-alpha]pyridinium-1-yl)methyl-3-cephem-4- carboxylate (9) and 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(6- methoxy[1,2,4]triazolo[1,5-alpha]pyridinium-1-yl)methyl-3-cephem-4- carboxylate (11) showed good antibacterial activity.

Cephalosporins↗
PubMed1992

Recording the bladder electromyogram for bladder activity evaluation during post-operative urinary urgency.

When the intravesical pressure cannot be measured because of continuous drainage, bladder electromyography is an alternative means of evaluating the functional condition of the urinary bladder. However, many problems that accompany this procedure have not been solved. In the present study we tried bladder electromyography with a newly-developed carbon fiber electrode in a patient who underwent an open prostatectomy. It was helpful in recognizing the relationship between urinary urgency and the spasmic activity of the vesicular detrusor muscle.

Aged↗
PubMed1992

[AFP producing gastric cancer manifested by metastasis to the tentorium cerebelli; case report and review of the literature].

We report a case of AFP producing gastric cancer manifested by metastasis to the tentorium cerebelli. A 66-year-old male patient was admitted with dysarthria, occipital headache and nausea on May 1, 1990. Neurological examination revealed signs of increased intracranial pressure and the right-sided cerebellar hemispheric signs. CT and MRI showed a round tumor shadow 3cm in diameter, which originated in the right-side tentorium cerebelli and grew in the posterior fossa. Tumor stains fed by the right tentorial artery were recognized by angiography. Serum AFP level was 503.5ng/ml. The patient underwent an operation under general anesthesia in the prone position. The tumor was totally removed via the suboccipital transtentorial approach. Histological examination revealed AFP producing adenocarcinoma. The patient was found to have a gastric cancer after neurosurgical operation, and underwent subtotal gastrectomy by surgeons. Serum AFP level was 254.5ng/ml after removal of metastatic brain tumor, and 5.0ng/ml after subtotal gastrectomy.

Adenocarcinoma↗
PubMed1992

[Effects of propentofylline (HWA285) on recovery of brain function following total cerebral ischemia (TCI) in dogs].

We examined the effects of a xanthine derivative, propentofylline, on recovery of brain function following TCI in 23 adult mongrel dogs. TCI was produced by clamping ascending aorta with aortoatrial bypass formation. The dogs were divided into 3 groups: preischemic administration (0.3 mg.kg-1.min-1, 30 min), post-ischemic administration (0.5 mg.kg-1.min-1, 6h) and control. The progress of recovery of EEG, respiration, reflexes, motor functions, arousal state and behavior were observed for 7 days after TCI and the latter 5 functions were analysed using neurologic deficit score (NDS). Propentofylline shortened the time necessary for reappearance of EEG after the starting of recirculation but could not improve the NDS.

Animals↗
PubMed1992

[Visualization of the intravesical urine stream].

Although many urodynamic techniques have been used to evaluate the function of the lower urinary tract, the principles of these measurements are only based on a relationship between flow rate and pressure. In addition to these measurements, the intravesical urine stream would provide useful information on urodynamics. We have experimentally attempted to visualize the urine stream in a bladder using transrectal ultrasound examination. Since an air-particle is a good target for ultrasound visualization, we instillated a 10% glycerine solution into the bladder for the maintenance of air-particles. Before instillation, this glycerine solution was strongly shaken so that air-particles were kept in the solution. The urine stream was successfully observed throughout the whole process of voiding. In video-recording analysis, the velocity of urine stream was measured by tracing some air-particles. The velocity of urine stream was approximately 28.4 cm/sec in the body and increased to 116.6 cm/sec at the bladder neck. Thus, the urine stream was accelerated toward the urethra during voiding. Therefore, it seems that visualization of the urine stream offers a new parameter for evaluation of urodynamic studies.

Humans↗
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↗