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Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 307 records · Page 17Linked to original sources
PubMed1994

Hair fibrous protein compositions in some hereditary hair abnormalities determined by two-dimensional polyacrylamide gel electrophoresis.

S-carboxymethylated (SCM) fibrous proteins (FPs) from the scalp hairs of the three different hereditary hair abnormalities (trichorrhexis invaginata in Netherton's syndrome, pili trianguli et canaliculi in uncombable hair syndrome, and fine hair in anhidrotic ectodermal dysplasia) were analyzed by two-dimensional polyacrylamide gel electrophoresis. Comparison of the SCM FP compositions of the three hair abnormalities with that of the normal revealed that the SCM FP compositions of these three abnormal hairs were all electrophoretically different from each other and that of the normal.

Child↗
PubMed1994

Arthritis and ankylosis in twy mice with hereditary multiple osteochondral lesions: with special reference to calcium deposition.

A murine autosomal recessive mutant named twy (tiptoe walking-Yoshimura) mouse showing multiple osteochondral lesions including ankylosis of the vertebral column and limb joints underwent sequential histopathological analysis of posterior limb joint lesions and intervertebral disc lesions. In the articular cartilage, a decrease in alcian blue-positive extracellular matrix and the presence of degenerated collagen fibers were found at the age of around 4-8 weeks. Calcium deposits in the articular cartilage were found at that time and later in the articular space and synovial tissue. Calcium deposits were also found in the intervertebral discs at 4 weeks. Using electron microscopy, some of the crystals were seen inside small vesicles. In both joints, degeneration of, and calcium deposition in, the articular cartilage progressed with age, finally producing bony ankylosis. These histological observations suggest that calcification and degeneration of the articular cartilage are the major factors in the pathogenesis of joint disorders in the twy mouse, and this mutant mouse provides a good model for studying the process and mechanism of osteoarthritic lesions, destructive arthritis and ankylosis.

Aging↗
PubMed1994

[A case of cardiogenic shock caused by Vibrio parahaemolyticus].

A case of a 53 year old healthy female complaining of diarrhea and abdominal pain after taking raw fish is presented. She immediately went into shock and unconsciousness. Central venous pressure was 8 cmH2O and her ECG showed a first-degree AV block and ST-T changes in almost all leads. After mechanical ventilation and administration of dopamine, dobutamine, cefotiam, ciprofloxacin, she became alert and recovered from her critical condition. V. parahaemolyticus which produces thermostable direct hemolysin (TDH) was cultured from the feces on admission. Kanagawa phenomenon was positive. Arterial blood culture was negative and the titer of serum endotoxin was low. The diagnosis of cardiogenic shock due to exotoxin produced by V. parahaemolyticus was made. Serological examination by ELISA showed elevation of IgG class antibody against TDH and TRH (TDH related hemolysin). And antibody against TDH was normalized after 180 days. By review of literature, there are some case reports of cardiogenic shock complicated with V. parahaemolyticus infection, but few showed elevation of antibody against TDH and TRH in the serum of the survived patient.

Endotoxins↗
PubMed1994

Dependence of LTP induction on postsynaptic depolarization: a perforated patch-clamp study in visual cortical slices of young rats.

1. To see whether there is a threshold of postsynaptic depolarization for induction of long-term potentiation (LTP) or depression (LTD) of synaptic transmission, perforated patch-clamp recordings were carried out under microscopic observation from 61 layer II/III neurons in visual cortical slices of young rats. Electrical stimulation given to nearby neurons was paired with stepwise shifts (30- or 300-ms duration) of clamped membrane potential of the recorded neurons to various levels. 2. Excitatory postsynaptic currents (EPSCs) were elicited by focal stimulation of a nearby pyramidal cell-like neuron. As the intensity of stimulation was increased, EPSCs emerged abruptly with 100% probability, and their peak latencies and amplitudes remained almost constant up to more than twice the threshold, indicating that the EPSCs were elicited monosynaptically. 3. LTP of EPSCs was induced in 11 of the 15 cells after pairing with a step to -20 mV and in 5 of the 14 cells after pairing with a step to -40 mV. No LTP was observed when the postsynaptic cells were clamped at -60, -70, or -90 mV. Significant LTD was not seen at any membrane potential level tested. There was no significant difference between the duration of potential shift of 30 and 300 ms during the pairing procedure in induction probability of LTP and magnitude of LTP, if it was induced. 4. These results suggest that LTP is induced by synaptic inputs associated with postsynaptic depolarization above the threshold around -40 mV at synapses linking layer II/III neurons in the developing visual cortex.

Age Factors↗
PubMed1994

Gonadotropin stimulates ovarian renin-angiotensin system in the rabbit.

The present study was undertaken to assess the role of ovarian renin-angiotensin system (RAS) in the preovulatory cascade induced by gonadotropin exposure. In the in vitro perfused rabbit ovaries, exposure to human chorionic gonadotropin (hCG) enhanced the secretion rate of angiotensin II (Ang II) within 1 h. The secretion rate reached maximal levels at 6 h and then declined thereafter. The intrafollicular Ang II content and renin-like activity were also significantly increased at 2 and 4 h after exposure to hCG, compared with control ovaries perfused with medium alone. The level of intrafollicular Ang II after hCG exposure significantly exceeded the concentration of Ang II in an equivalent volume of plasma. The addition of 1 microM captopril to the perfusate significantly inhibited the secretion rate of Ang II stimulated by hCG; however, captopril affected neither the ovulatory efficiency nor prostaglandin production in ovaries treated with hCG. Captopril significantly inhibited the resumption of meiosis in the ovulated ova and follicular oocytes stimulated by hCG. The administration of 100 micrograms Ang II at 2-h intervals to the perfusate reversed the inhibitory effects of captopril on hCG-induced oocyte maturation. In conclusion, these data indicate that gonadotropin stimulates renin-like activity and Ang II production in the rabbit ovary. Ovarian renin-angiotensin system may play an important role in the process of oocyte maturation after exposure to gonadotropin.

Angiotensin II↗
PubMed1994

Growth hormone stimulates follicular development by stimulating ovarian production of insulin-like growth factor-I.

The present study was undertaken to investigate the effects of GH on follicular growth, oocyte maturation, ovulation, and production of insulin-like growth factor-I (IGF-I) in the in vitro perfused rabbit ovaries. Ovulation did not occur in any ovaries perfused with GH at a concentration of 1, 10, 100, or 200 ng/ml, but the addition of GH to the perfusate increased the follicle diameter in a dose-dependent manner. The production of IGF-I by ovaries perfused with medium alone was very low throughout the perfusion period. The addition of 100 ng/ml GH to the perfusate significantly increased ovarian production of IGF-I at 4, 6, 8, and 12 h compared with the contralateral control ovaries. Changes in the tissue concentrations of IGF-I in ovaries perfused with 100 ng/ml GH paralleled those triggered by exposure to 50 IU human CG (hCG). When the effect of GH on the tissue concentration of IGF-I was determined at 4 h, GH stimulated the tissue concentration of IGF-I in perfused rabbit ovaries in a dose-dependent manner. The percent increase in follicle diameter in ovaries treated with GH was significantly correlated with the intraovarian IGF-I content. The mean number of ovulations per ovary and the ovulatory efficiency were significantly reduced in ovaries perfused with 5 IU hCG, compared with those in ovaries perfused with 50 IU hCG. The addition of 100 ng/ml GH to the perfusate significantly increased the ovulatory efficiency and follicle diameter in the 5 IU hCG-treated ovaries. Exposure to GH significantly stimulated the resumption of meiosis in the follicular oocytes compared with that in ovaries perfused with medium alone. Furthermore, GH significantly stimulated the resumption of meiosis in ovulated ova and follicular oocytes in ovaries treated with 5 IU hCG. Thus, exposure to GH-stimulated follicular growth, oocyte maturation, and production of IGF-I in the in vitro perfused rabbit ovaries, which indicates that the ovary is in fact a site of GH reception and action. Additionally, GH enhanced the effects of gonadotropins, acting synergistically to promote the ovulatory process. These observations suggest that GH may amplify gonadotropin actions in the process of follicular development and ovulation, at least in part, by stimulating ovarian IGF-I production.

Animals↗
PubMed1994

Novel antitumor sesquiterpenoids in Achillea millefolium.

Three new antitumor sesquiterpenoids, achimillic acids A, B and C, were isolated as methyl esters from Achillea millefolium and their structures were determined spectroscopically. The compounds were found to be active against mouse P-388 leukemia cells in vivo.

Animals↗
PubMed1994

Sensitivity of intestinal alkaline phosphatase to L-homoarginine and its regulation by subunit-subunit interaction.

The inhibitory effect of levamisole and L-homoarginine on alkaline phosphatases (ALP, orthophosphoric monoester phosphohydrolase, EC. 3.1.3.1) in various tissues was studied to characterize differences in the mechanism of inhibition of ALP isoenzymes. The ALP activity from the placenta, kidneys, and a clonal osteogenic cell line, MC3T3-E1, was hyperbolically inhibited with a dependency on the concentration of levamisole (Ki0.5 = 10-12 microM) or L-homoarginine (Ki0.5 = 1 mM), but the activity of intestinal ALP was little inhibited by 240 microM levamisole and sigmoidally inhibited by L-homoarginine (Ki0.5 = 13 mM). Hill plot analysis of the L-homoarginine inhibition data showed that the Hill coefficient values of the placenta, kidney, and osteogenic cells were around 0.9-1.0 and that of the intestine was 1.8. The effect of sodium dodecyl sulfate (SDS), which may decrease the subunit-subunit interaction, on the L-homoarginine inhibition of the intestinal ALP was tested. The L-homoarginine concentration-dependent inhibition curve changed from sigmoidal to hyperbolic, and the Hill coefficients decreased with increasing concentrations of SDS. These results suggest that the differences in inhibition by L-homoarginine and affinity changes of intestinal ALP for L-homoarginine are caused by the subunit-subunit interaction of oligomers.

Alkaline Phosphatase↗
PubMed1994

Inhibition of gonadotrophin-induced ovulation in rabbits by perfusion with dibutyryl cAMP via reduction of ovarian prostaglandin production.

The role of cAMP in ovulation, oocyte maturation and prostaglandin production was assessed using a rabbit ovary preparation perfused in vitro. Dibutyryl cAMP (10(-3), 10(-4) or 10(-5) mol l-1) was added to the perfusate of one ovary. The contralateral, control ovary was perfused with medium alone. Thirty minutes after the onset of perfusion, 50 iu hCG was added to the perfusate of all ovaries. Dibutyryl cAMP inhibited hCG-induced ovulation in a dose-related fashion. No difference in ovum maturity or degeneration was found between control ovaries and ovaries treated with dibutyryl cAMP. Ovarian progesterone production was not affected by exposure to dibutyryl cAMP. The concentrations of 6-keto PGF1 alpha (the stable metabolite of prostacyclin) and PGF2 alpha in the perfusate of ovaries treated with dibutyryl cAMP were 49.6% and 32.0% of the control values, respectively, 12 h after hCG administration. Inhibition of 6-keto PGF1 alpha production by dibutyryl cAMP was dose related. Production of PGE2 was unaffected by dibutyryl cAMP. These data raise the possibility that continuous exposure to dibutyryl cAMP may inhibit hCG-induced ovulation in the perfused rabbit ovary via a reduction in PGF2 alpha and prostacyclin production.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

[Warm heart surgery facilitates atrioventricular valve repair].

The valve structure varies with cases in children's atrioventricular valvular regurgitation. Filling the left ventricle simply with cold saline solution and testing the valve competency in the cold cardioplegic arrest do not clarify true valve function, although it was the widely used method. Three dimensional evaluation of the lesion in the dynamic and more nearly normal state and the very fine operative procedure in the static state are required for the successful repair. For this purpose we employed the warm heart surgery on 12 children for valve repair (age 1.3-10.1 years, body weight 6.6-28.2 kg). Because no topical cooling was used, preparation of the heart from the adhesion caused by previous operation was not necessary. The aorta was cross clamped at the temperature of 34 degrees of centigrade with continuous coronary perfusion and the lesion in the valve structure and the regurgitation stream were inspected in the beating state, then the repair was performed in the arrest state obtained by infusing the potassium into the coronary perfusion line. Beating and arrest was repeated 2-5 times by on-off potassium infusion until the repair seems satisfactory. In two cases, the repair was not feasible and mitral valve replacement was performed, but in other 10 cases, the postoperative regurgitation decreased down to the grade 2. Despite prolonged aortic cross clamping (65-216 min), post-operative course was quite satisfactory without low-output syndrome in any cases. Postoperatively administered maximum dose of Dopamine was 4.0 +/- 2.2 micrograms/kg/min. CK-MB at 1 POD was also within normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Temperature↗
PubMed1994

[Application of the warm heart surgery to the open heart surgery in children].

Application of the warm heart surgery to the children's open heart surgery has been reluctant, because keeping the operative field dry thought to be difficult. In this report, the clinical result of 22 cases of children's open heart surgery using warm heart surgery (Warm Group) was compared with that of other 25 cases using conventional cold cardioplegia (Cold Group). In warm group, rectal temperature was kept at 34 degrees C, continuous coronary perfusion rate was 3 ml/kg/min, and potassium ion concentration for inducing the initial cardiac arrest was 20 mEq/l, and the maintaining dose was 12-17 mEq/l. There were two deaths in Cold group. In warm group, keeping the operative field dry was not difficult by using the specially devised small sucker (2 mm diameter) and, if necessary, temporarily stopping the coronary perfusion (maximum for 7 min). Aorta cross cramping time/total extracorporeal circulation time, CK-MB at 1-POD and maximum dose of dopamine and dobutamine proved the better myocardial protection in warm group (p < 0.01). From this study, it was concluded that warm heart surgery can be applied for children with no difficulty, and showed superior myocardial protection.

Body Temperature↗
PubMed1993

Nonpeptide angiotensin II receptor antagonists. Synthesis and biological activity of potential prodrugs of benzimidazole-7-carboxylic acids.

In order to improve the oral bioavailability (BA) of 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimid azole - 7-carboxylic acid (3: CV-11194) and 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4- yl]methyl]-1H-benzimidazole-7-carboxylic acid (4: CV-11974), novel angiotensin II (AII) receptor antagonists, chemical modification to yield prodrugs has been examined. After selective tritylation of the tetrazole rings in 3 and 4, treatment of N-tritylated benzimidazole-7-carboxylic acids (6, 7) with a variety of alkyl halides, followed by deprotection with hydrochloric acid, afforded esters of 3 and 4. Mainly 1-(acyloxy)alkyl esters and 1-[(alkoxycarbonyl)oxy]alkyl esters, double ester derivatives, were synthesized. Their inhibitory effect on AII-induced pressor response in rats and oral BA were investigated. (Pivaloyloxy)methyl and (+/-)-1-[[(cyclohexyloxy)-carbonyl]oxy]ethyl esters of 3 and 4 showed marked increases in oral bioavailability which significantly potentiated the inhibitory effect of the parent compounds on AII-induced pressor response. Among them, (+/-)-1-[[(cyclohexyloxy)carbonyl]oxy]ethyl 2- ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimida zole- 7-carboxylate (10s, TCV-116) was selected as a candidate for clinical evaluation.

Administration, Oral↗
PubMed1993

A mouse homolog of the Escherichia coli recA and Saccharomyces cerevisiae RAD51 genes.

Analysis of mitotic and meiotic recombination in mammalian cells has been hampered by the complexity of the reactions involved as well as lack of mutants. Furthermore, none of the genes involved in the process has yet been identified. In budding yeast, Saccharomyces cerevisiae, the RAD51 gene is essential along with other genes of the RAD52 epistasis group for mitotic and meiotic recombination and DNA repair. The Rad51 protein is structurally similar to Escherichia coli RecA protein, which is required in homologous recombination and SOS responses in bacteria. Here we report the isolation of a mouse homolog of the yeast RAD51 gene. The amino acid sequence predicted from the gene shows 83% and 55% homology with those of the yeast RAD51 and the E. coli recA product, respectively. The mouse gene complemented a rad51 mutation of S. cerevisiae with sensitivity to methyl-methanesulfonate, which produces double-strand breaks of DNA. This gene is expressed in the thymus, testis, ovary, spleen, and intestine, suggesting that its product is involved in mitotic and meiotic recombination in addition to DNA repair.

Amino Acid Sequence↗
PubMed1993

ADP modifies the function of the glucose transporter: studies with reconstituted liposomes.

Modification of function of the glucose transporter by nucleotides was studied by using liposomes reconstituted with the human erythrocyte glucose transporter. ADP enclosed in the liposomes inhibited the uptake of D-glucose and nicotinamide in a dose-dependent manner, but other enclosed nucleotides (ATP, AMP, CDP, GDP, UDP) showed no effect on the uptake of both. Only intraliposomal ADP was effective, and extra-liposomal ADP was not, under our experimental conditions. Intraliposomal ADP did not change Km, but decreased Vmax to approximately one-third of control for uptake of both D-glucose and nicotinamide. However, the binding and the affinity of cytochalasin B to the reconstituted liposomes were not affected by intraliposomal ADP. The uptake of uridine was not changed in the presence of ADP, indicating that the nucleoside transporter co-existing in the liposomal membranes is not regulated by ADP. Human erythrocytes whose intracellular ATP was decreased by Ca2+ ionophore A23187 also showed decreased uptake of 2-deoxy-D-glucose and nicotinamide. This phenomenon was very similar to that found in the liposomes. These findings suggest the possibility that the function of the glucose transporter is directly and negatively modified by an increased concentration of intracellular ADP.

Adenosine Diphosphate↗
PubMed1993

c-fos m-RNA expression after treatment with fetal bovine serum and epidermal growth factor for osteoblastic MC3T3-E1 cells cultured in a low calcium environment.

This paper examines the existence of c-fos mRNA expression in osteoblastic MC3T3-E1 cells cultured in a low calcium environment. The MC3T3-E1 cells were placed in a serum free medium for 24 hours after subconfluence and then the cells were treated with fetal bovine serum and epidermal growth factor for 0, 5, 10, 15, 30, or 60 minutes. The c-fos m-RNA expression was found in the MC3T3-E1 cells cultured in both normal medium (control group) and low Ca medium (low Ca groups). The degree of expression was significantly higher in the low Ca group than in the control group in each treatment period (p < 0.01) and in both groups, after the treatment with FBS or EGF, the expression levels increased with time at 5 and 10 minutes but decreased at 15 minutes. Thereafter, levels increased again to reach to a maximum at 30 minutes after which it decreased rapidly. On the other hand, in both groups, after the treatment with EGF, the expression increased at 30 minute. This suggests that the MC3T3-E1 cells placed in a low calcium environment react to restore cell functioning to normal at the gene level.

Animals↗