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Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 235 records · Page 13Linked to original sources
PubMed1996

Enhancement of mRNA expression of tissue-type plasminogen activator by L-threo-3,4-dihydroxyphenylserine in association with ocular dominance plasticity.

Tissue-type plasminogen activator (tPA) plays important roles in the regulation of synaptic plasticity in the hippocampus and cerebellum. We found that the expression of tPA mRNA in the visual cortex was increased significantly by the peripheral administration of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS; 100 mg/kg, i.p.), which we had previously shown to have a promotive effect on ocular dominance (OD) plasticity. When plasminogen activator inhibitor-1 (PAI-1; 100 muM in an osmotic minipump) was infused into the kitten visual cortex, OD plasticity was suppressed; i.e. a significantly large number of binocular cells was recorded in the PAI-1 infused cortex following monocular deprivation. These results, therefore, suggest that the PA system is involved in the promotive effect of L-threo-DOPS in OD plasticity.

Animals↗
PubMed1996

Interactions between insulin-like growth factor-I (IGF-I) and the renin-angiotensin system in follicular growth and ovulation.

The interactions between insulin-like growth factor-I (IGF-I) and the renin-angiotensin system (RAS) in follicular growth and ovulation were studied with the use of an isolated perfused rabbit ovary preparation. Ovulation failed to occur in either control ovaries or the experimental ovaries perfused with IGF-I in a concentration of 1, 10, or 100 ng/ml in the absence of gonadotropin. Exposure to IGF-I stimulated the secretion rate of angiotensin II-like immunoreactivity (Ang II-IR) in perfused rabbit ovaries in a dose-dependent manner. The percent increase in follicle diameter in ovaries perfused with IGF-I for 12 h was significantly correlated with the secretion rate of Ang II-IR at 12 h after exposure to IGF-I. The addition of IGFBP-3 to the perfusate did not induce ovulation in the absence of gonadotropin, but exposure to IGFBP-3 inhibited hCG-induced ovulation in a dose-dependent manner. In addition, IGFBP-3 significantly reduced the ovarian secretion rate of Ang II-IR and prostaglandins stimulated by hCG administration. Intrafollicular plasminogen activator (PA) activity significantly increased within 4 h after exposure to 100 ng/ml of IGF-I, compared with that in control ovaries perfused with medium alone. The concomitant addition of IGFBP-3 to the perfusate significantly reduced the IGF-I-stimulated PA activity in the preovulatory follicles at 4, 6, and 8 h after exposure to IGF-I. However, IGFBP-3 alone affected neither the ovarian secretion rate of Ang II-IR nor intrafollicular PA activity. Exposure to streptokinase, an exogenous PA, in vitro stimulated both follicular growth and the intrafollicular Ang II-IR content. In conclusion, IGF-I enhances both ovarian Ang II production and follicular development by stimulating intrafollicular PA activity.

Angiotensin II↗
PubMed1996

Targeted disruption of the Rad51 gene leads to lethality in embryonic mice.

The mouse Rad51 gene is a mammalian homologue of the Escherichia coli recA and yeast RAD51 genes, both of which are involved in homologous recombination and DNA repair. To elucidate the physiological role of RAD51 protein, the gene was targeted in embryonic stem (ES) cells. Mice heterozygous for the Rad51 null mutation were intercrossed and their offspring were genotyped. There were no homozygous (Rad51-/-) pups among 148 neonates examined but a few Rad51-/- embryos were identified when examined during the early stages of embryonic development. Doubly knocked-out ES cells were not detected under conditions of selective growth. These results are interpreted to mean that RAD51 protein plays an essential role in the proliferation of cell. The homozygous Rad51 null mutation can be categorized in cell-autonomous defects. Pre-implantational lethal mutations that disrupt basic molecular functions will thus interfere with cell viability.

Alleles↗
PubMed1996

Ultramicro-analysis by use of light-scanning photoacoustic densitometry for electrophoresed protein in human hair.

A technique was developed for the ultramicro-analysis of proteins electrophoresed by Laemmli's method using a light-scanning photoacoustic densitometer. After electrophoresis, the proteins were blotted on a nitrocellulose membrane filter and colored by the avidin-biotin complex method. This filter was then measured using a photoacoustic densitometer. The optimal blotting time was 150 min. The relative standard deviation of four measurements was 3.89% for 200 ng bovine serum albumin (BSA). The limits of detection were 2.3, 0.69, 4.4, and 2.9 ng (S/N = 3) for BSA, ovalbumin, carbonic anhydrase, and alpha-Lactoalbum respectively. Proteins eluted from hair by various harmful agents, such as a surfactant and UV irradiation, were analyzed by the present method. Using 2-mercaptoethanol, the molecular weights of proteins in hair were in the range of 14,000-64,000. Maximal elution of protein was obtained at pH 8. More protein was eluted under alkaline conditions than under acidic conditions. A protein of Mr 68,000 was eluted from hair by oxidative treatment with either UV irradiation or sodium bromate.

Acoustics↗
PubMed1996

Cell cycle-dependent expression of the mouse Rad51 gene in proliferating cells.

The mouse Rad51 gene is a mammalian homologue of the Escherichia coli recA and yeast RAD51 genes, both of which are involved in homologous recombination and DNA repair in mitosis and meiosis. The expression of mouse Rad51 mRNA was examined in synchronized mouse m5S cells. The Rad51 transcript was observed from late G1 phase through to M phase. During the period of late G1-S-G2, the RAD51 proteins were observed exclusively in nuclei. Activation by mitogens of T cell and B cell proliferation in spleen induced the expression of Rad51 mRNA. By immunohistochemical analyses, in mouse RAD51 protein was detected in proliferating cells: spermatogonia in testis, immature T cells in thymus, germinal center cells of the secondary lymphatic nodules of spleen and intestine, follicle cells in ovary and epithelial cells in uterus and intestine. It was also expressed in spermatocytes during early and mid-prophase of meiosis and in resting oocytes before maturation. Thus, mouse Rad51 expression is closely related to the state of cell proliferation and is presumably involved in DNA repair coupled with DNA replication, as well as in meiotic DNA recombination in spermatocytes.

Animals↗
PubMed1996

Characterization of conjugated metabolites of a new angiotensin II receptor antagonist, candesartan cilexetil, in rats by liquid chromatography/electrospray tandem mass spectrometry following chemical derivatization.

Combined liquid chromatography and electrospray mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (MS/MS) were used for the characterization of the conjugated metabolites (glucuronides) of a new angiotensin II receptor antagonist, candesartan cilexetil (TCV-116; (+/-)-1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-¿[2'-(1H-tetrazol-5-yl)biphenyl- 4-yl]methyl¿-1H-benzimidazole-7-carboxylate) in the plasma and bile of rats given the drug. The glucuronides of the active component, M-I (candesartan), in rat plasma and bile were positional isomers with respect to the binding site of glucuronic acid. The site of glucuronidation in M-I was not directly identified by mass spectrometry. However, the structure of the isomers could be elucidated by the MS/MS analysis of dimethylated glucuronides prepared by the reaction of glucuronide isomers with diazomethane: N-glucuronide of M-I (M-I-NG) in the plasma and acyl glucuronide (M-I-AG) in the bile. The results obtained in this study indicated that LC/ESI-MS/MS analysis provides the detailed structure of conjugated metabolite by simple chemical derivatization.

Angiotensin II↗
PubMed1996

Effect of a low-calcium environment on alkaline phosphatase activity in embryonic rat calvarial bone cells in culture.

The effect of a low Ca environment on the alkaline phosphatase (ALP) activity in bone cells was examined. Bone cells were isolated from the calvaria of 18 to 21-day-old fetal rats and cultured in BGJ b or alpha-minimum essential medium (alpha-MEM) with calcium concentrations of 1.87 mM (control group), 1.20 mM (middle group) or 0.34 mM (low-Ca group). The control and low-Ca groups grew and reached a confluent state at 10 days of culture and there were no significant differences in the number of cells, total protein, or DNA content between the two groups. The specific ALP activity measured at 10 days of culture of the cells with 0.34, 1.20 and 1.87 mM calcium was 106.3 +/- 11.9, 73.3 + 10.4, and 38.8 +/- 7.3 unit per mg protein (n = 9), respectively. When the low-Ca medium was replaced with the control medium during 10 days of culture, the activity decreased to the level of the control group. On the other hand, when control medium was replaced with low-Ca medium, the activity increased to the level of the low-Ca group. After confluence, cell growth in the low-Ca group was poorer than that in the control group with time. The ALP activity markedly increased and the mineralized nodular structures were observed in the control group of alpha-MEM, but not in the low-Ca group. These findings suggest that stimulation of ALP activity is a compensation mechanism to maintain normal cell functions in a low-Ca condition and that the role of ALP in the low-Ca environment may be different from that on mineralization.

Alkaline Phosphatase↗
PubMed1996

One-stage reconstruction of full-thickness lower eyelid defects using a subcutaneous pedicle flap lined by a palatal mucosal graft.

The authors previously reported a subcutaneous pedicle flap pivoting on the lateral canthus to reconstruct the skin of a whole eyelid as an aesthetic unit. A palatal mucosal graft was added to line the conjunctival side of the flap to make a one-stage reconstruction of the full-thickness eyelid. Although it is becoming popular to use the palatal mucosa as a conjunctival substitute, there are very few reports on the one-stage reconstruction of the eyelid. Two patients with total defects of the lower eyelid resulting from resection of malignant skin tumours have been treated using this technique. The functional and aesthetic results have been excellent in both cases.

Aged↗
PubMed1996

An improvement in the embryo quality and pregnancy rate by the pulsatile administration of human menopausal gonadotropin in patients with previous unsuccessful in vitro fertilization attempts.

OBJECTIVE: To examine whether the pulsatile administration of hMG improves IVF outcomes in patients with previous unsuccessful attempts using IM injections of hMG. DESIGN: A prospective randomized study. SETTING: In vitro fertilization program at a university hospital. PATIENTS: Eighty-eight endocrine-normal ovulatory women under 40 years of age, with normal male partners and a history of unsuccessful IVF treatment by the IM administration of hMG. INTERVENTIONS: Patients were assigned randomly to receive either IM (bolus group) or pulsatile administration of hMG (pulsatile group) after pituitary desensitization by a GnRH agonist. MAIN OUTCOME MEASURES: The proportion of retrieved oocytes with a polar body, the number of fertilized oocytes and embryos, the proportion of morphologically superior embryos, and the rate of pregnancy per initiated cycle were compared. RESULTS: The proportion of retrieved oocytes with a polar body and the number of fertilized oocytes and embryos were similar in both groups. Significantly more embryos had superior morphology in the pulsatile group (77%) than the bolus group (52%). The rates of overall and clinical pregnancy per initiated cycle were significantly higher in the pulsatile group (39% and 30%, respectively, n = 44) than in the bolus group (18% and 11%, respectively, n = 44). CONCLUSION: In women with failed IVF attempts using IM administration of hMG, the pulsatile administration of hMG produces superior embryos and, hence, a higher pregnancy rate.

Adult↗
PubMed1996

A novel method of ovarian stimulation for in vitro fertilization: bromocriptine-rebound method.

OBJECTIVE: To examine whether a new method of ovarian stimulation, bromocriptine-rebound method, improves IVF outcomes compared with the conventional long protocol of GnRH agonist and hMG regimen. DESIGN: A prospective clinical trial. SETTING: In vitro fertilization program at a university hospital. PATIENTS: Endocrine-normal ovulatory women less than 40 years of age, with normal male partners and previous failed IVF-ET using long protocol. INTERVENTIONS: Patients were assigned to either bromocriptine-rebound method (group 1) or long protocol (group 2). The bromocriptine-rebound method was the same as the long protocol, except that bromocriptine was administered daily from day 4 of the preceding cycle until 7 days before hMG stimulation. MAIN OUTCOME MEASURES: The number of cleaved and morphologically superior embryos, pregnancy rate per oocyte pick-up, and serum PRL concentrations during administrations of hMG. RESULTS: Significantly more embryos were cleaved and had superior morphology in group 1 than group 2. Clinical and ongoing pregnancy rates per oocyte pick-up were significantly higher in group 1 (42% and 38%, respectively) than group 2 (24% and 21%, respectively). The mean PRL concentration was significantly higher in the group 1 than group 2. A significant correlation between the number of superior embryos and PRL concentrations was observed in group 1, but not in group 2. CONCLUSION: The bromocriptine-rebound method enhanced embryonic development, resulting in an increased pregnancy rate compared with the long protocol.

Adult↗
PubMed1996

Purification and characterization of active fragment of Ca2+/calmodulin-dependent protein kinase II from the post-synaptic density in the rat forebrain.

Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) of the post-synaptic density (PSD) was solubilized and activated 4- to 5-fold by limited alpha-chymotrypsin digestion with prior autophosphorylation of the kinase. The enzyme was also activated by trypsin and mu-calpain, a Ca(2+)-dependent protease. The active catalytic fragment was purified to homogeneity using gel filtration and ion exchange chromatography. The purified active fragment was completely Ca2+/calmodulin-independent and exists as a monomer. Kinetic studies with the purified fragment revealed similar Km values for ATP and synthetic peptide substrate, and an about 8-fold increment in Vmax, compared with native PSD CaM kinase II.

Animals↗
PubMed1996

Identification and partial amino acid sequences of seven S-RNases associated with self-incompatibility of Japanese pear, Pyrus pyrifolia Nakai.

S-allele-specific proteins (S-proteins) were separated and identified by two-dimensional (2D) gel electrophoresis from the style extract of 14 cultivars of Japanese pear, Pyrus pyrifolia Nakai, which exhibits gametophytic self-incompatibility. These S-proteins were 30-32 kDa basic proteins with putative pIs of 9.6-10.1 and were distinct from the other proteins, which were common for all cultivars examined. Each S-protein was assigned to a given S-genotype based on electrophoretic mobility and the partial amino acid sequence. For S1- to S7-proteins, five different N-terminal amino acid sequences sharing the YFQFTQQY sequence were determined. Since the same N-terminal amino acid sequences were found for both S1- and S7-proteins, and for S3- and S5-proteins, the two S-proteins of each pair were distinguished based on their electrophoretic behavior. The internal amino acid sequences of S2- and S4-proteins, determined for Achromobacter protease I (API) digests, revealed that these proteins are S2- and S4-RNases, respectively. In the cultivar Nijisseiki, these two RNases were expressed from the white bud to mature flower stages when the cultivar acquires and enforces self-incompatibility. Osa-nijisseiki, a self-compatible mutant of Nijisseiki, produced S2-RNase, but did not produce S4-RNase. The absence of S4-RNase was also observed in self-compatible offsprings derived from Osa-Nijisseiki. These results suggest that Japanese pear in the family Rosaceae possesses a gametophytic self-incompatibility system involving an S-RNase, and that a reduction or lack of expression of S4-RNase in the style is responsible for the self-compatibility of Osa-Nijisseiki.

Alleles↗
PubMed1996

Function of beta 1 integrins on human decidual cells during implantation.

In the present study, the effects of antibodies against specific beta 1 integrin heterodimers on mouse embryo attachment and spreading were tested to identify the role of the beta 1 integrins in early implantation. We developed assays for the attachment of mouse embryos and for trophoblastic spreading on cultured human decidual cells. Blastocysts became attached to the cultured decidual cells in the presence of a purified mouse monoclonal IgG1 antibody (negative control) after the embryos hatched from the zona pellucida. The majority of hatched blastocysts attached within 24 h of culture. Blastocysts that were attached to decidual cells exhibited extensive outgrowth after 48 h. The addition of antibodies directed against the beta 1 and alpha integrin subunits to the cultured decidual cells did not affect the rates of hatching or attachment of the blastocysts. However, the outgrowth of embryos on the decidual cells was inhibited by the addition of a monoclonal antibody against the beta 1 subunit in a dose-dependent manner, implying that blastocyst attachment and outgrowth are mediated by different mechanisms. Although the area of trophoblast outgrowth in the presence of a mouse monoclonal lgG1 antibody was increased during 96 h of culture, anti-beta 1 antibody blocked the outgrowth of trophoblasts in a dose-dependent manner. Both the incidence and extent of trophoblastic outgrowth were also significantly reduced in the presence of antibodies against the alpha 1, alpha 2, alpha 5, and alpha 6 subunits. These observations suggest that beta 1 integrins on decidual cells may be involved in blastocyst development and differentiation following attachment.

Adult↗
PubMed1996

Effects of insulin-like growth factor-I on follicle growth, oocyte maturation, and ovarian steroidogenesis and plasminogen activator activity in the rabbit.

We examined the effects of insulin-like growth factor (IGF)-I on follicular growth, oocyte maturation, and ovarian steroidogenesis and plasminogen activator (PA) activity in vitro, using a perfused rabbit ovary preparation in order to determine whether the follicle-stimulating effects of growth hormone (GH) are mediated by IGF-I. The addition of IGF-I to the perfusate stimulated follicular growth and the resumption of meiosis in follicular oocytes in a dose-dependent manner. There was no significant difference in the production of progesterone by perfused rabbit ovaries between IGF-I-treated and control ovaries, whereas IGF-I increased the production of estradiol (E2) by perfused rabbit ovaries in a dose-dependent manner. The concomitant addition of a monoclonal antibody recognizing the type I IGF receptor, alpha IR-3, to the perfusate significantly blocked IGF-I-stimulated follicular growth, oocyte maturation, and E2 production. Intrafollicular PA activity increased significantly 4 h after exposure to 10 or 100 ng/ml of IGF-I and reached maximal levels at 6 h. The percentage increase in follicle diameter at 6 h after exposure to IGF-I was significantly correlated with the intrafollicular PA activity. Treatment with GH resulted in a 2.7-fold increase in intrafollicular levels of IGF-I mRNA. The binding of [125I]-IGF-I to rabbit ovarian membrane preparations was inhibited by unlabeled IGF-I and IGF-II in a concentration-dependent manner. The relative affinity of the IGF-I receptor for IGF-I, IGF-II, and insulin was typical of type I binding (IGF-I > IGF-II > insulin). Affinity cross-linking of ovarian membranes with [125I]-IGF-I revealed a radiolabeled band corresponding to a molecular weight of 135,000, the alpha subunit of the type I IGF receptor. This band was totally displaced by IGF-I and alpha IR-3. It was concluded that IGF-I stimulated follicular development, E2 production, and oocyte maturation by interacting with its specific receptor located in rabbit ovarian membranes.

Animals↗
PubMed1996

Involvement of angiotensin II in the process of gonadotropin-induced ovulation in rabbits.

In the present study we investigated the role of angiotensin II (Ang II) receptor subtypes in gonadotropin-induced ovulation, oocyte maturation, and ovarian steroidogenesis and prostaglandin (PG) production in in vitro-perfused rabbit ovaries. The addition to the perfusate of PD123319, a nonpeptide Ang II antagonist with a high affinity for AT2 receptors, inhibited hCG-induced ovulation in a dose-dependent manner, whereas CV-11974, a nonpeptide AT1 receptor antagonist, had no effect. The majority of ovulated ova and follicular oocytes resumed meiotic maturation in response to hCG; and PD123319, but not CV-11974, significantly inhibited hCG-induced oocyte maturation. The addition of both Ang II receptor antagonists to the perfusate had no significant effect on the concentration of progesterone in the perfusate of hCG-treated ovaries, whereas PD123319 inhibited the hCG-stimulated production of estradiol. The production of PGE2 and PGF2 alpha was significantly increased at 6 h in hCG-treated ovaries compared with ovaries before hCG administration. PD123319 inhibited the hCG-stimulated production of PGs by perfused rabbit ovaries in a dose-dependent manner, indicating that hCG-induced PG synthesis is mediated, at least in part, via the activation of AT2 receptors. Ovulatory efficiency in ovaries perfused with or without PD123319 in the presence of hCG was significantly correlated with PG production by perfused rabbit ovaries 12 h after exposure to hCG (r = 0.6553 for PGE2, p < 0.001; r = 0.4758 for PGF2 alpha, p < 0.05). In conclusion, Ang II exerts complex and coordinated control on at least two distinct aspects in the normal ovulatory process, ovulation and oocyte maturation. Ang II produced locally by gonadotropin exposure may be a part of a novel intraovarian paracrine or autocrine control mechanism that operates via the AT2 receptor in the ovary.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1996

Relationship of cigarette smoking to blood pressure and serum lipids and lipoproteins in men.

1. The relationship of cigarette smoking to blood pressure and serum lipids and lipoproteins was studied in 7608 men, ranging from 40 to 59 years of age. Analyses were performed separately for non-drinkers and drinkers. 2. After adjusting age and body mass index (BMI) in non-drinkers and age, BMI and alcohol intake in drinkers in forward stepwise multiple regression analysis, there was a dose-dependent negative relationship between cigarette smoking and diastolic blood pressure (DBP) and high density lipoprotein cholesterol (HDL-C), regardless of drinking habit. There was a dose-dependent positive relationship between cigarette smoking and the ratio of total cholesterol (TC) to HDL-C (TC:HDL-C) in non-drinkers, but not in drinkers. There was a dose-dependent negative relationship between cigarette smoking and TC and a positive relationship between cigarette smoking and triglycerides (TG) in drinkers, but not in non-drinkers. 3. After matching age and BMI in non-drinkers, subjects who smoked more than 30 cigarettes/day had significantly lower mean values of systolic blood pressure (SBP; 4.3%; P < 0.05), DBP (3.0%; P < 0.01) and HDL-C (15.5%; P < 0.01) and higher mean values of TC:HDL-C (25.0%; P < 0.01), TG (46.8%; P < 0.01) and beta-lipoprotein (12.0%; P < 0.01) than non-smokers. In drinkers, after matching age, BMI, and alcohol intake, subjects who smoked more than 30 cigarettes/day had significantly lower mean values of SBP (2.8%; P < 0.05), DBP (4.8%; P < 0.01), HDL-C (17.3%; P < 0.01) and TC (4.4%; P < 0.01) and higher mean values of TC:HDL-C (15.4%; P < 0.01) and TG (45.1%; P < 0.01) than non-smokers. 4. Although the results are somewhat variable, the present study reveals that cigarette smoking is negatively associated with SBP and DBP and unfavourably associated with lipids and lipoproteins, regardless of drinking habit.

Adult↗