Biomedical subjects

T Kuwayama

Publications and source records attributed to T Kuwayama.

At least 19 recordsLinked to original sources

PubMed2006

The effect of glucose on the progression of the nuclear maturation of pig oocytes.

The progression of the nuclear maturation of oocytes is a useful marker for the estimation of the subsequent developmental competence of oocytes. In this study, we examined the effect of energy substrates in an in vitro maturation medium on the progression of the nuclear maturation of oocytes. In experiment 1, the supplementation of the maturation medium with 0, 5 and 10 mM of glucose lead to increase in the total cell number of the blastocysts. In experiments 2 and 3, the maturation phase was divided into two stages (germinal vesicle (GV) stage: 0-20 h and nuclear maturation stage: 20-44 h), and the effects of glucose or pyruvate added at each stage on the kinetics of nuclear maturation were examined. The addition of glucose at the nuclear maturation stage rather than at the GV stage of maturation effected greater acceleration in the progression of nuclear maturation. However, the addition of pyruvate at both stages had the same effect on the progression of nuclear maturation was the same. In addition, when glucose was added to the medium containing pyruvate, an additive effect on the progression of nuclear maturation was observed (experiment 4). In experiment 5, the inhibitors of glucose-6-phosphate dehydrogenase (G6PD), dehydroepiandrosterone (DHEA) and 6-aminonicotinamide (6-AN) decreased the rate of the final maturation of oocytes and reduced the difference between the rates of the final maturation of oocytes cultured with glucose and those cultured with pyruvate. In the experiment 6, when the activator of G6PD, brilliant cresyle blue (BCB), was added to the maturation medium, the progression of nuclear maturation was significantly accelerated. The results of this study suggested that in addition to the role of an energy substrate, glucose or its metabolites play a role in nuclear maturation. This role was more pronounced at the second stage of maturation (transition from GV breakdown (GVBD) to M2), probably due to the metabolism of glucose via the pentose phosphate pathway (PPP) rather than the glycolysis pathway.

6-Aminonicotinamide↗

PubMed2006

Inhibitory effects of calcium ionophore pretreatment of porcine oocytes on polyspermic fertilization.

The present study examined the inhibitory effects of various pretreatment concentrations (0-100 microM) of the calcium ionophore A23187 on polyspermic fertilization and then examined the effect of the maturation period and the time between calcium ionophore treatment and fertilization on the inhibitory effect of calcium ionophore on polyspermic fertilization. In experiment 1, a high concentration of calcium ionophore (100 microM) increased the rate of activated oocytes, but the rate of fertilization declined. On the other hand, when oocytes were treated with a low concentration of calcium ionophore (10 microM), monospermic fertilization was significantly increased (10 microM; 31.3%) (p < 0.05). In experiment 2, oocytes were cultured for various times (0, 0.5, 3, 6 h) after calcium ionophore treatment (10 microM) before fertilization. The highest rate of monospermic fertilization was detected in the oocytes cultured for 6 h after calcium ionophore treatment before fertilization. In experiments 3 and 4, we examined the effect of the maturation period (40 h or 44 h) on the rate of fertilization and blastulation of oocytes pretreated with calcium ionophore. The treatment of oocytes with calcium ionophore significantly decreased the rate of polyspermic fertilization regardless of the maturation period (44 h: with calcium ionophore 26.25% vs without 78.8%; 40 h: with calcium ionophore 37.5% vs without 77.5%); however, calcium ionophore treatment increased the rates of monospermic fertilization and blastulation of the oocytes matured for 44 h, but not those matured for 40 h. In conclusion, activation with a low concentration of calcium ionophore (10 microM) and a further 6 h of culture before fertilization improved the rate of monospermic fertilization and blastulation.

Animals↗

PubMed2005

Comparison between the characteristics of follicular fluid and the developmental competence of bovine oocytes.

There are great differences in the developmental competence of oocytes collected from individual cows. Oocytes grow and mature in the follicular fluid (FF). In the present study, characteristics of the FF of each ovary and the developmental competence of enclosed oocytes were investigated, and these data were then compared. A total of 37 pairs of ovaries were collected from beef heifers. The concentration of magnesium (Mg), aspirate aminotransferase (AST), nonesterified fatty acids (NEFA), and lactate dehydrogenase (LDH) in the FF were great compared with serum standard. Several significant correlations among these characteristics were detected. Forty-eight hours after fertilization, the stage of embryo development at an advanced developmental stage (>6 cell stage) is related to the rate of blastulation 8 days after fertilization. In addition, a significantly positive or negative correlation was observed between the developmental competence (the rate of cleavage in the embryo and blastulation) and the concentration of the icterus index (ICT) or blood urea nitrogen (BUN) in the FF. In conclusion, the quality of oocytes is affected by the environment in the follicle, and BUN or ICT is a predictable index of the developmental competence of oocytes.

Animals↗

PubMed2005

Cardio-ankle vascular index (CAVI) for the monitoring of the atherosclerosis after heart transplantation.

Atherosclerosis has been reported to progress rapidly after heart transplantation. A quantitative diagnosis is required for the diagnosis of atherosclerosis after heart transplantation. In this study, we compared brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) for the diagnosis. The average values of both baPWV and CAVI in the seven cases after heart transplantation were found to be signif-icantly large in comparison to the average values of the normal healthy people of the same age group. When comparisons were made before and after the heart transplantation in a particular case, CAVI was stable and baPWV changed sharply. A lot of parameters such as blood pressure, blood volume, etc. have been reported to influence baPWV. The results of this study suggested that CAVI was a stable parameter in comparison to baPWV even after heart transplantation. Thus, CAVI may be useful in the diagnosis of arteriosclerosis after heart transplantation.

Adolescent↗

PubMed2005

Chaos analysis of electro encephalography and control of seizure attack of epilepsy patients.

In order to evaluate the EEG of patients with epilepsy, chaos analysis was performed for the subdural EEG time series data. The chaos attractor was reconstructed in the phase space and the correlation dimension. KS entropy calculated from the Lyapunov exponents was evaluated. Before the seizure attack, the KS entropy showed a lower value when compared with the time series data recorded during healthy condition. The results of our study suggest that it is possible to predict the seizure attack by the chaos analysis of the EEG signal. Further, we aim at developing an automatic control system for predicting a seizure attack by the use of local cooling of the focus with Peltier elements.

Algorithms↗

PubMed2005

Modification of ovary stock solution with magnesium and raffinose improves the developmental competence of oocytes after long preservation.

During ovary storage oocytes lose some of their developmental competence. In the present study, we maintained storage solutions of phosphate-buffered saline (PBS) at various temperatures (20 or 35 degrees C) or supplemented them with magnesium (Mg), raffinose and sucrose. Subsequently, we examined the kinetics of electrolytes in the follicular fluid (FF) during the ovary storage period (9 h), the survival rate of granulosa cells in the follicles, and the developmental competence of oocytes after the storage. Lowering the temperature from 35 to 20 degrees C increased the total cell number of blastocysts that developed at 7 days after in vitro maturation and in vitro fertilization of oocytes. In stock solution with supplements of 15 mM Mg or a combination of 5 mM Mg and 10 mM raffinose or sucrose, a significantly higher number of oocytes developed into blastocysts with a large number of cells in each blastocyst, and a significantly higher number of living granulosa cells were obtained as compared with stock solutions without any supplements. During ovary storage, the concentrations of potassium and chloride in the FF were increased, and the addition of Mg to the stock solution increased the concentration of Mg in the FF. Germinal vesicle breakdown in oocytes that were collected from ovaries stored in the solution supplemented with 15 mM Mg or a combination of 5 mM Mg and 10 mM of raffinose occurred at a slower rate than that in oocytes collected from ovaries stored in PBS alone. On the other hand, the oocytes collected from ovaries stored in the solution supplemented with 15 mM Mg or a combination of 5 mM Mg and 10 mM raffinose reached the metaphase II (MII) stage more rapidly than the oocytes collected from ovaries stored in the PBS alone. In conclusion, the modification of stock solution by the addition of Mg and raffinose improved the developmental competence of oocytes obtained from ovaries preserved for a long period.

Animals↗

PubMed2000

Parathyroid hormone receptor binding property in the shell gland of oviduct of the guineafowl during an oviposition cycle.

Parathyroid hormone (PTH) receptor binding property in the membrane fraction of the endometrium of the shell gland (uterus) of the guineafowl was analyzed by the use of [125I]PTH-related peptide (PTHrP) binding assays. Specificity, reversibility, and saturation of binding were demonstrated. Scatchard plots revealed a single class of binding sites. The equilibrium dissociation constant (Kd) was 0.50 to 1.15 nM in laying birds and 1.07 to 1.16 nM in nonlaying birds. The maximum binding capacity (Bmax) per milligram of membrane protein was 65.2 to 110.9 femtomoles (fmol) in laying birds and 105.8 to 120.6 fmol in nonlaying birds. Both Kd and Bmax values changed within the above range during an oviposition cycle in laying birds, showing a decrease during the period of eggshell formation. No change was found in nonlaying birds. The results suggest that PTH/PTHrP receptors are present in the shell gland of the guineafowl, and their binding may be related to eggshell formation.

Animals↗

PubMed1999

Prostaglandin F concentration in serum of hens and cocks.

Prostaglandin F (PGF) concentrations in the serum of laying and nonlaying hens and of cocks at various times during a day were measured by radioimmunoassay. The serum concentration of PGF was higher in laying hens than in nonlaying hens or cocks without regard to time of day. In all birds, the concentration showed a peak at 2 h after onset of light (0700 h). In laying hens on the day of laying the fourth egg of a sequence, two peaks were found: one at 2 h after onset of light and another at the time immediately after oviposition. The results suggest that the serum concentration of PGF in both male and female chickens shows a daily change and that in laying hens it also shows a change associating with oviposition.

Animals↗

PubMed1997

Effects of 17 beta-estradiol and progesterone on migration of human monocytic THP-1 cells stimulated by minimally oxidized low-density lipoprotein in vitro.

OBJECTIVE: Many epidemiological studies have shown that postmenopausal hormone replacement therapy (HRT) has a beneficial effect on atherosclerotic cardiovascular disease. The aim of this study was to investigate the effects of estrogen and progestin on the migration of monocytes induced by minimally oxidized low-density lipoprotein (m-ox-LDL) in vitro. METHODS: Human monocytic THP-1 cells were used for the study. Migration assay was performed using a modified Boyden chamber. RESULTS: The presence of estrogen receptors was determined in THP-1 cells by Western and Northern blot analysis. Although native LDL had no significant effects on the migration of THP-1 cells, m-ox-LDL increased the migration of THP-1 cells in a dose-dependent manner. Although 17 beta-estradiol (E2, 10(-9)-10(-6) M) inhibited the 10 micrograms/ml-induced migration of THP-1 cells in a dose-dependent manner, estrone (E1), estriol (E3) and progesterone (P) had no significant effects. The combination of P (10(-9)-10(-6) M) did not show any effect on the inhibitory effect of 10(-7) M E2. Preincubation of THP-1 cells with the anti-estrogenic agent, tamoxifen (10(-6) M), significantly antagonized the inhibitory effect of 10(-7) M E2. m-ox-LDL stimulated MCP-1 secretion from THP-1 cells, which was reduced by E2. Anti-human MCP-1 neutralizing antibody inhibited the migration of THP-1 cells stimulated by m-ox-LDL. E2 also inhibited the 10 ng/ml MCP-1-induced migration of THP-1 cells in a dose-dependent manner. CONCLUSIONS: These findings suggest that the inhibitory effect of E2 on the migration of monocytes might be one of the factors involved in the decreased incidence of atherosclerotic cardiovascular disease in premenopausal women and postmenopausal HRT.

Adult↗

PubMed1997

Effects of 17beta-estradiol and progesterone on the adhesion of human monocytic THP-1 cells to human female endothelial cells exposed to minimally oxidized LDL.

It is known that hormone replacement therapy inhibits the progression of atherosclerosis in postmenopausal women. Focal attachment of monocytes to endothelial cells is observed in early atherosclerotic lesions. The aim of this study was to investigate the effects of 17beta-estradiol (E2) and progesterone on the adhesion of human monocytic THP-1 cells to human female aortic endothelial cells (HAECs) in vitro. Minimally oxidized low-density lipoprotein (LDL) significantly increased THP-1 cell adhesion to HAECs as compared with native LDL at the same concentration. Though E2 inhibited minimally oxidized LDL-induced THP-1 cell adhesion in a dose-dependent manner, progesterone had no significant effects. Preincubation of HAECs with tamoxifen significantly antagonized the inhibitory effect of E2. These findings suggest a beneficial effect of hormone replacement therapy on atherosclerosis.

Adult↗

PubMed1997

Direct action of melatonin on hen ovarian granulosa cells to lower responsiveness to luteinizing hormone.

The presence of a melatonin-binding component in the membrane fraction of the ovarian granulosa cells of hens that has characteristics of a receptor such as high affinity, limited capacity, reversible binding, and binding specificity was demonstrated by radioligand binding assays. When the cells were incubated in vitro with various concentrations of luteinizing hormone (LH) in the presence and absence of melatonin (1 and 5 nM), the dose-response curve for the LH-stimulated progesterone production was shifted to a higher concentration of LH: ED50 of LH was approximately two times greater in the presence of melatonin. The results suggest a direct action of melatonin on the ovarian granulosa cells of the hen to lower the responsiveness to LH for progesterone production.

Animals↗

PubMed1992

Effects of removal of chicks from hens on concentrations of prolactin, luteinizing hormone and oestradiol in plasma of brooding Gifujidori hens.

Gifujidori hens were allowed to repeat a breeding cycle in one season. In the first breeding cycle the duration of the brooding (raising chicks) stage was limited to 3 weeks, whereas in the second breeding cycle it was limited to 1 week by removing all chicks from mother hens. In the first breeding cycle, plasma prolactin (PRL) was high during the incubation period, but rapidly decreased on the day of hatching and reached minimum values about 1 week after hatching. In contrast, plasma luteinizing hormone (LH) concentrations were low during the incubation period, but after hatching they gradually increased and reached peak values immediately after removal of chicks. Concentrations of oestradiol in plasma were low in the incubation and brooding stages but increased significantly immediately after removal of chicks. In the second breeding cycle, changes in PRL and LH concentrations were similar to those observed in the first breeding cycle except that even greater increases in plasma LH and oestradiol concentrations were observed one week after hatching when the chicks were removed. These results suggest that coexistence of newly hatched chicks may suppress LH secretion from the pituitary of the hen in the natural breeding cycle.

Animals↗

PubMed1991

Characterization of benzodiazepinooxazoles: crystal and molecular structure of trans and cis isomers of oxazolam.

The stereochemistry of the trans and cis isomers of 2(S)- and 2(R)-oxazolam is described. A total of four molecular structures of the 11b(R) and 11b(S) diastereomers of 2(S)- and 2(R)-oxazolam have been revealed by X-ray diffraction techniques. 2(S)-Oxazolam crystallizes in space group P2(1)/c, with cell dimensions a = 16.180(2) A, b = 8.791(2) A, c = 13.574(2) A, and beta = 102.07(1) degrees. The molecule in an asymmetric unit exhibited disorder at the 2-carbon (C2) atom, and the structures for trans and cis isomers have been resolved crystallographically. 2(S)-Oxazolam forms polymeric chains with intermediation of ethanol through hydrogen bonding. 2(R)-Oxazolam crystallizes in space group P1, with cell dimensions a = 7.754(1) A, b = 8.654(1) A, c = 15.795(2) A, alpha = 104.09(1) degrees, beta = 91.19(1) degrees, and gamma = 114.00(1) degrees. A similar disorder at the C2 position has been elucidated by a mixture of trans- and cis-2(R)-oxazolams. The two 2(R)-oxazolam molecules form a dimer with a hydrogen bond net. The structural details, focusing on the conformation and molecular complex formation of both oxazolams, have been discussed in connection with the oxazolidine ring stability and the crystal polymorph.

Anti-Anxiety Agents↗

PubMed1990

[The behavior of 1,4-benzodiazepine drugs in acidic media. XVI. Estimation of cis/trans isomer ratio of benzodiazepinooxazoles using nuclear magnetic resonance shift reagent].

The ratio of cis/trans isomers (referring to 11b-substituent and 2- or 3-substituent) of benzodiazepinooxazoles was estimated by using the lanthanide shift reagent (Eu(fod)3-d27) for nuclear magnetic resonance (NMR) spectroscopy. The amide carbonyl oxygen at 6-position is considered to coordinate with the reagent, because the largest downfield shifts were observed at the amide carbonyl carbon (C-6) in 13C-NMR and the amide hydrogen (H-7) in 1H-NMR. The ratios depend largely on the substituents at 11b-, 2-, and 3-positions. The cis isomer for compounds having 11b-hydrogen increases with an increase in the bulkiness of the substituents at 2-position. The cis isomer for compounds having 3-methyl group decreases with change from 11b-2'-chlorophenyl group (mexazolam) to 11b-hydrogen.

Benzodiazepines↗

PubMed1988