Biomedical subjects

M Yonezawa

Publications and source records attributed to M Yonezawa.

At least 19 recordsLinked to original sources

PubMed1995

Comparative study of erythrocyte deformability in maternal and cord blood.

To elucidate the rheological difference in maternal and fetal blood by determining erythrocyte deformability, 20 pairs of mothers and newborns, and 20 nonpregnant women were studied. Erythrocyte deformability was measured by means of an electron spin resonance method. Erythrocyte deformability was dependent on the hematocrit, and there was an optimal hematocrit value at which the deformation was maximal. The hematocrit at which the deformability was maximal showed a lower value (32 to 35%) in maternal blood; conversely, a higher value (47 to 50%) occurred in fetal blood than that (40 to 43%) in nonpregnant control women. When the hematocrit of the red blood cell suspension in dextran solution was adjusted to 40% (nonpregnant blood), 35% (maternal blood), and 50% (fetal blood), the deformability of fetal erythrocytes was significantly higher than maternal blood (P < 0.05), and its value was almost similar to that of nonpregnant control women. Based on our results, erythrocyte deformability of fetal blood is much higher compared with the maternal blood, suggesting the effective oxygen supply to the fetal tissues even in the circumstances of lower oxygen tension.

Adult↗

PubMed1995

Analysis of the NH2-terminal 83rd amino acid of Escherichia coli GyrA in quinolone-resistance.

Artificial mutations of Gyrase A protein (GyrA) in Escherichia coli by site-directed mutagenesis were generated to analyze quinolone-resistant mechanisms. By genetic analysis of gyrA genes in a gyrA temperature sensitive (Ts) background, exchange of Ser at the NH2-terminal 83rd position of GyrA to Trp, Leu, Phe, Tyr, Ala, Val, and Ile caused bacterial resistance to the quinolones, while exchange to Gly, Asn, Lys, Arg and Asp did not confer resistance. These results indicate that it is the most important for the 83rd amino acid residue to be hydrophobic in expressing the phenotype of resistance to the quinolones. These findings also suggest that the hydroxyl group of Ser would not play a major role in the quinolone-gyrase interaction and Ser83 would not interact directly with other amino acid residues.

4-Quinolones↗

PubMed1993

Role of the amino-terminal amino acid sequences determining the in vitro refolding process of prochymosin polypeptide.

Prochymosin, a zymogen of an aspartic proteinase chymosin, is produced as inclusion bodies in the recombinant Escherichia coli cells. Solubilization of the inclusion bodies with 8 M urea followed by dialysis at pH 10.5 achieves correctly refolded prochymosin to some extent, which is then activated by self-processing at acidic pHs. Analyses of the alkaline dialysates by anion exchange chromatography revealed broad distribution of prochymosin polypeptides with different conformations. Stepwise dialysis with a slower decreasing rate of urea resulted in marked improvement of the yield of correctly refolded molecules. A hybrid prochymosin (CR601) possessing a short NH2-terminal replacement with the trp-leader peptide was not refolded into the correct conformation by one-step dialysis, but it was by stepwise dialysis. Replacement of Lys at the NH2-terminal second position of CR601 with Asp or Glu caused marked enhancement of correct refolding. These findings suggest that the amino acid sequence in the NH2-terminal region of prochymosin plays a crucial role in determining the whole refolding process of the polypeptide.

Amino Acid Sequence↗

PubMed1992

Developmental changes of glutamate dehydrogenase activity in rat liver mitochondria and its enhancement by branched-chain amino acids.

The developmental changes of glutamate dehydrogenase activity in the fetal and neonatal rat liver were investigated, as well as the effects of branched-chain amino acids on this enzyme. Hepatic glutamate dehydrogenase activity showed a marked increase at the end of the fetal period and peaked on the 5th day of neonate at approximately 3 times higher than the adult level. Glutamate dehydrogenase was activated by leucine, isoleucine, and valine in this order when they were added to isolated intact liver mitochondria in vitro. The enhancement of enzyme activity was more marked in fetal rats than in adults. In contrast, when branched-chain amino acids were added after disrupting the mitochondrial membrane by sonication, only leucine slightly activated glutamate dehydrogenase, while isoleucine and valine slightly inhibited its activity. Our findings suggest that glutamate may be actively synthesized in the developing rat liver mitochondria and then transaminated to other nonessential amino acids for protein synthesis, and that increased intramitochondrial branched-chain amino acid concentrations may enhance glutamate dehydrogenase activity. This anabolic metabolism will contribute to the fetal growth and development.

Amino Acids, Branched-Chain↗

PubMed1992

Development changes of polyamine biosynthesis in rat liver.

To investigate the role of polyamine metabolism in fetal development, we determined the hepatic polyamine content and the activity of enzymes related to polyamine metabolism in fetal, newborn and adult rats. In the fetuses, spermidine was detected at the highest level, followed by spermine and then putrescine. Putrescine and spermidine levels were higher in the fetuses than in adult rats, while the spermine level was significantly lower in the fetuses. The activities of the enzymes investigated were also higher in the fetuses than in adult rats. These findings indicate that polyamine synthesis was enhanced in the fetal liver, and that degradation of spermidine via spermidine N1-acetyltransferase contributes to the increase in putrescine levels. Thus, our study suggests that an increase in putrescine is important for fetal growth and that putrescine per se has a significant role in fetal cellular proliferation.

Acetyltransferases↗

PubMed1992

[Tryptophan and its metabolite concentrations in human plasma during the perinatal period].

The concentration of tryptophan (free and protein bound) and its metabolites in the plasma of the maternal vein and in the umbilical vein, umbilical artery and neonatal vein were determined by high performance liquid chromatography. The plasma levels of tryptophan and most of its metabolites in the umbilical vein and artery were significantly higher than those in the maternal vein. Especially the 3-OHAA level in umbilical blood was approximately 50 times as high as that in maternal blood. The concentration of total tryptophan in the plasma of the neonatal vein showed a marked decrease at one day after birth in comparison with that at birth, but the total kynurenine concentration was not decreased in the plasma of the neonatal vein. In the blood, ratios of free to total tryptophan and kynurenine were kept at a constant level throughout the perinatal period. In conclusion, the present study suggests that tryptophan metabolism may play an important role in fetal development.

Chromatography, High Pressure Liquid↗

PubMed1992

The whale (Odontoceti) spleen: a type of primitive mammalian spleen.

Three spleens from two Odontoceti species were studied histo-anatomically. These spleens consisted of lymphatic nodules, the red pulp (broad sense), and the trabeculo-capsular system composed of the elasto-fibroleiomyocytic tissue. The periarterial lymphatic sheath (PALS) was unclear. Two layers, the intermediate zone and perivenous layer, were distinguishable in the red pulp (broad sense). The perivenous layer was narrow in width and consisted of venules and the intervascular reticular tissue rich in myeloid cells. The collecting and drainage veins were enclosed in this layer. The perivenous layer corresponds to the red pulp (narrow sense) of the common mammalian spleen and may be under involution in a process that probably relates to the remodelling of the intrasplenic vein. The pattern of the arteriovenous communication seemed to be closed, and no ellipsoids were noted around arterial terminals. The Odontoceti spleen has two venous drainage routes (hilar and capsular systems), suggesting a primitive state of evolution, and may be an additional example of the primitive mammalian spleen.

Animals↗

PubMed1991

Localization and developmental change of indoleamine 2,3-dioxygenase activity in the human placenta.

Previously, we pointed out the importance of the kynurenine metabolism in fetuses and neonates. We examined localization and developmental change of indoleamine 2,3-dioxygenase activity in human placenta. The indoleamine 2,3-dioxygenase was found localized in syncytiotrophoblast in the placenta. The indoleamine 2,3-dioxygenase activity was not detected in placenta in the early stage of gestation. It was first detected at around 14 weeks of gestation, increased rapidly thereafter and was maintained at high levels till near term. The indoleamine 2,3-dioxygenase activity was significantly lower in placenta with retarded intrauterine development. These results suggest the importance of placental indoleamine 2,3-dioxygenase during fetal development.

Female↗

PubMed1990

[The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin in women].

The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin were studied in 11 normal cycling women during their follicular phases. Blood samples were obtained via an indwelling venous catheter every 10 min. for 2.5 hours starting at 9:30 and 21:30h. For the blood samplings taken at night, six women were kept in a dark room and were permitted to sleep. Their blood samples were obtained using a flashlight (5-10 lux) without their rest being disturbed. However, the other five women were exposed to light (3,000 lux at eye level) and awakened from 22:40 to 24:00h. Plasma melatonin concentrations in the morning decreased from 48.7 +/- 11.6 pg/ml at 9:30h to 24.7 +/- 4.0 pg/ml at 12:00h. On the other hand, plasma melatonin concentrations at night increased from 65.4 +/- 9.6 pg/ml at 21:30h to 138.2 +/- 28.6 pg/ml at 24:00h. The pulsatile LH secretion was changed from the type of "high frequency, low amplitude" in the morning to the type of "low frequency, high amplitude" at night. Nocturnal FSH concentrations were lower than diurnal ones, but nocturnal prolactin concentrations were higher than diurnal ones. Nocturnal concentrations of melatonin were suppressed 40 min. after the light exposure (from 117.4 +/- 11.4 pg/ml at 22:40h to 74.6 +/- 13.9 pg/ml at 23:20h). On the the other hand, the light exposure increased plasma prolactin concentrations from 10.9 +/- 4.1 ng/ml at 22:40h to 17.0 +/- 4.4 ng/ml at 22:50h, maintained those higher levels for 20 min. and decreased them gradually after 23:20h. With the light exposure, mean values of nocturnal LH concentrations were increased from 11.9 +/- 1.5 mIU/ml before exposure to 14.2 +/- 1.8 mIU/ml after exposure, and those of FSH were also increased from 5.9 +/- 0.4 mIU/ml to 6.3 +/- 0.4 mIU/ml. These results showed that the secretion of melatonin, as well as LH, FSH and prolactin had daily rhythms and that melatonin and prolactin showed different responses to light exposure, suggesting different control mechanisms for the secretion of those two hormones.

Adult↗

PubMed1990

Peripheral neuropathy in xeroderma pigmentosum.

The pathology of the peripheral nervous system (PNS) in 2 autopsied cases of group A xeroderma pigmentosum (De Sanctis Cacchione syndrome) are presented. Motor nerves including those of the oculomotor systems were severely affected, but involvement of the sensory system was even more marked. Minor hypertrophic changes were present in the distal portions of the peripheral nerve trunks, but there was no appreciable difference in the density of myelinated nerve fibres between proximal and distal levels. Morphometric data including teased fibre analyses and g ratio scattergrams suggest that the underlying pathogenetic mechanism is that of a neuronopathy. Unmyelinated axons were also severely depleted. Review of the previous literature revealed that the pathological changes of the PNS in group A xeroderma pigmentosum are thought to be slowly progressive, which is also suggested by the severe and widespread sclerotic changes of the CNS in the present 2 cases.

Adult↗

PubMed1990

Adrenoleukodystrophy associated with cerebral arteriovenous malformation.

Adrenoleukodystrophy (ALD) is now considered to be an X-linked recessive peroxisomal disorder. We report the case of a patient with ALD associated with a left parietal arteriovenous malformation (AVM) who deteriorated progressively six months after recovery from a hemorrhage of the AVM. Serial CT scans and MR imagings showed progressive demyelination spreading from the affected area. This case suggests that local brain damage due to AVM hemorrhage may accelerate the progress of demyelination.

Adrenoleukodystrophy↗

PubMed1990

Acquired radioresistance after low dose X-irradiation in mice.

Low doses (2.5-15 cGy) of X-irradiation two months prior to a second exposure to a sublethal dose enhanced the survival rate in mice. Optimal and significant increase was observed with 5-10 cGy. Endogenous spleen colony counts (endo-CFUs) after 7 Gy increased by a factor of about 1.7 in mice pre-irradiated with 5-10 cGy, while the number of blood forming stem cells (CFUs) in the pre-irradiated group did not exceed that in the sham-irradiated control group at the period of the second exposure (two months after irradiation with 5 cGy). The low dose exposure seems to stimulate recovery of blood forming stem cells after the second irradiation and favors a decrease in the incidence of bone marrow death.

Animals↗

PubMed1990

[A determination of anti-insulin receptor antibody in serum--a radioreceptor assay excluded the influence of insulin and anti-insulin antibody].

We studied an anti-insulin receptor antibody (IRAb) assay that excludes the influence of serum insulin and anti-insulin antibody in patients with anti-insulin antibody and normal subjects. The placental membranes strongly bound with 125I-insulin at 4 degrees C. The insulin specificity of the radioreceptor assay was confirmed by adding excess non-labeled insulin and other human hormones to the assay system. The strong correlation between the receptor binding reactivity (%) and the anti-insulin antibody levels was noted in the conventional direct IRAb assay (r = -0.95), but not in the present IRAb assay (r = 0.46) in 10 clinical samples. The placental membranes were stable as the target insulin receptor for IRAb assay at -80 degrees C for at least 4 months. A significant difference in IRAb levels was found between 10 patients with positive anti-insulin antibody and 20 normal controls (p less than 0.01, student t test). The coexistence of insulin and anti-insulin antibody were removed by absorbance to silicagel and by utilizing the two-step (indirect) assay, respectively. IRAb assay without the influence of serum cofactors showed excellent reproducibilities (CV 4.4% (N = 5) and 12.5% (N = 5) in within and between assay variations, respectively).

Autoantibodies↗

PubMed1990

[Clinical significance of measurement of plasma melatonin concentration in women with irregular menstrual cycles].

To study the effects of melatonin on the human hypophyseal ovarian axis, we measured the concentrations of melatonin in the plasma of women with a regular menstrual cycle and of women with an abnormal menstrual cycle, at days 5 through 10 after the onset of menstruation or withdrawal bleeding. In seven women with a regular menstrual cycle, there was a tendency for the plasma melatonin concentration to gradually decrease chronologically from 49.0 +/- 9.8pg/ml (M +/- S.E.) at 9:30 h to 19.0 +/- 4.0pg/ml at 12:00 h. On the other hand, the plasma melatonin concentration at 21:30 h was 50.3 +/- 7.4pg/ml which was almost the same as the level at 9:30 h, while the concentration during the night significantly increased chronologically to 106.3 +/- 28.6pg/ml at 24:00 h. By comparing the plasma melatonin concentration measured during the day with that measured during the night, a significant difference was discovered after 21:40 h (p less than 0.05). The plasma melatonin concentration at 10:00 h and 22:00 h in 20 women with a regular menstrual cycle was 28.1 +/- 3.4pg/ml and 72.2 +/- 9.9pg/ml, respectively, showing a diurnal rhythm with a significantly higher level during the night than during the day. On the other hand, the plasma melatonin concentration in most of the women with an anovulatory cycle or amenorrhea was within the range of the mean level of +/- 1.5 x the standard deviation obtained from the 20 women with a regular menstrual cycle. However, an increase in plasma melatonin during the night was not found in three of nine women with an anovulatory cycle and one of two women with second grade amenorrhea.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian Rhythm↗

PubMed1990

[A case of three-year-old boy with periodic apnea during waking and sleep, severe psychomotor retardation and hypotonia].

We presented a 3-year-old boy, a product of consanguineous parents, with periodic apnea during waking and sleep states, severe psychomotor retardation and hypotonia. According to polysomnographical recordings, he exhibited frequent central apneas which decreased in frequency and regularity in the stage REM. He showed abnormal background EEG, undifferentiated sleep stage and very short duration of stage REM. The initiation of breathing after apnea was often accompanied with generalized muscles contraction like a startle response. In the waking state the apnea induced generalized muscular hypotonicity and the decline of wakefulness. Arterial CO2 and O2 saturation was within normal limits. It was suggested that the malfunction of the brain stem responsible for the control of breathing, sleep-wakefulness cycle and determination of sleep stages was closely connected with the pathogenesis of abnormal breathing patterns.

Apnea↗

PubMed1989

Hodgkin's disease in a killer whale (Orcinus orca).

Hodgkin's disease (HD) is reported in a killer whale (Orcinus orca). Generalized lymphadenopathy and splenomegaly were noted at necropsy and histopathological examination revealed diffuse proliferation of atypical large cells with huge eosinophilic nucleoli. They were often multinucleated, and binucleated forms characteristic of Sternberg-Reed cells of human HD were occasionally present. There was no cytological atypia in the background lymphocytes. Thus, the lesion was identified as analogous to HD in man. To our knowledge, this is the first recorded case of HD in the killer whale.

Animals↗

PubMed1989

Radiation protection by Shigoka extract on split-dose irradiation in mice.

Radioprotective effect of a Shigoka extract was studied on split-dose irradiation. Mice were exposed to 4 Gy X 4 or 3 Gy X 4 for examining survival ratio or hemogram, respectively. The extract was i.p. injected immediately after each irradiation. The extract significantly (p less than 0.001) increased the survival ratio, and it increased leukocyte count within the period of the death (days 2-12 after the final exposure). Cerebral hemorrhage after 4 Gy X 4 was diminished by the extract. Recovery of leukocytogenesis seems much more important for survival at split-dose irradiation than at single acute irradiation.

Animals↗

PubMed1989

[ELISA for platelet-associated IgG, IgM, and C3, and their clinical application].

The platelet-associated IgG (PAIgG) has been reported to elevate in the patients with idiopathic thrombocytopenic purpura (ITP) and other autoimmune diseases. However, low PAIgG levels have been often recognized in thrombocytopenia. We speculated about the increasing of other platelet-associated proteins in those patients, and tried to determine platelet-associated IgM (PAIgM) and platelet-associated C3 (PAC3) using a high sensitive competitive micro-ELISA as well as PAIgG. Our results showed the specific elevation of PAIgM and PAC3 in thrombocytopenia as well as the PAIgG level (p less than 0.01). Further, the weak correlations among these levels were found (PAIgG/PAIgM: n = 7, correlation coefficient (r) = 0.55, PAIgG/PAC3: n = 73, r = 0.61, PAIgM/PAC3: n = 56, r = 0.39). We discussed on the possibility that the PAIgM and PAC3 also could be an indicator for the platelet injury and may cause the short platelet life span resulting thrombocytopenia as well as PAIgG.

Autoantibodies↗