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S Mimura

Publications and source records attributed to S Mimura.

At least 19 recordsLinked to original sources
PubMed2001

Effect of bile acids on formation of azoxymethane-induced aberrant crypt foci in colostomized F344 rat colon.

The effect of bile acids on the formation of azoxymethane induced aberrant crypt foci (ACF) was investigated using the fecal stream-excluded colons of colostomized F344 rats. The excluded colon was irrigated with saline or bile acids (1 mg/0.5 ml per day, 5 days/week) for 4 weeks. The mean numbers of ACF per colon in rats given cholic acid, deoxycholic acid (DCA), chenodeoxycholic acid (CDCA), lithocholic acid, and ursodeoxycholic acid (UDCA) were 160.8, 118.2, 227.8, 150.7 and 87.3, respectively, while that of the control was 174.0. The number of ACF was significantly larger in CDCA, but smaller in UDCA and DCA-treated rats than the control (P<0.01). DCA did not induce apoptosis in the colon under the present conditions.

Animals↗
PubMed2001

Carbamoyl phosphate synthetase I deficiency: molecular genetic findings and prenatal diagnosis.

We report a Japanese boy who died at Day 28 of life because of severe carbamoyl phosphate synthetase I (CPS1) deficiency that was proven by enzyme assay. By analysis of cDNA and genomic DNA, he was shown to be a compound heterozygote with two point mutations of the CPS1 gene, 840G>C leading to an aberrant splicing and 1123C>T (predicting Q375X). The 840G>C was a mutation described in another Japanese family. Since his parents carried each mutation heterozygously, we performed prenatal diagnosis at 16 weeks of his mother's next gestation by multiplex PCR and melting curve analysis in a single capillary containing two-color fluorescent (LC-Red 640 and LC-Red 705) probes on LightCycler. We analyzed genomic DNA extracted from amniotic cells and found that the fetus was homozygous for the wild-type alleles. At term a healthy girl was born without hyperammonemia.

Carbamoyl-Phosphate Synthase I Deficiency Disease↗
PubMed2001

A prospective clinical study on inhaled nitric oxide therapy for neonates in Japan.

BACKGROUND: This is the first report about a prospective clinical investigation to study the efficacy and safety of nitric oxide (NO) inhalation in infants with persistent pulmonary hypertension of the newborn (PPHN) in Japan. METHODS: Patients in the present study had to meet the following entry criteria: (i) they had to be younger than 7 days of age; (ii) they had to have evidence of PPHN as defined by echocardiograph; (iii) they had to have severe systemic hypoxemia under mechanical ventilation at 100% oxygen supplementation; and (iv) they had to have a failure to respond to conventional therapies. Patients were excluded from this trial if they had any of the following: hypoplastic lung, structural cardiac lesions or severe multiple anomalies. RESULTS: Nitric oxide inhalation therapy was performed in 68 infants who had severe PPHN at 18 hospitals between May 1995 and May 1997. At birth, 21 of 68 infants (31%) weighed less than 1,500 g and 39 infants weighed more than 2,500 g. The diagnoses associated with PPHN were as follows: 27 infants had meconium aspiration syndrome, 15 infants had dry lung syndrome, nine infants had congenital diaphragmatic hernia, six infants had respiratory distress syndrome, three infants had pneumonia and eight infants had other diagnoses. The mean oxygenation index (OI) before NO inhalation therapy in 68 infants was 43.2; 55 infants (81%) had good responses. CONCLUSIONS: These results may be valuable for further randomized controlled and double-blind trials in Japan to evaluate whether NO inhalation therapy is more effective than conventional therapy in infants with severe PPHN.

Administration, Inhalation↗
PubMed2001

Plasma and erythrocyte levels of trace elements and related antioxidant enzyme activities in low-birthweight infants during the early postnatal period.

UNLABELLED: To discover the relationship between antioxidant enzyme activities and trace elements in low-birthweight infants during the early postnatal period, we analysed catalase (CAT), CuZn-superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GSH-Px) activities in erythrocytes. and compared them with Fe, Cu. Zn and Se levels in plasma, and Cu, Zn and Se levels in erythrocytes until 16 wk after birth. Thirteen low-birthweight infants whose mean birthweight and gestation were 1520 +/- 293 g and 32.0 +/- 2.8 wk were enrolled in this study. All infants were without chronic complications, well nourished, and predominantly fed standard formula or preterm formula based on cow's milk, commercially available in Japan. Cu and Zn levels in erythrocytes did not decline after birth, in contrast to a temporal decrease in plasma Zn. Erythrocyte CAT activity was significantly higher at 16 wk than that at birth or 4 wk of age. Erythrocyte CuZn-SOD activity did not change throughout the study period. Only Se in plasma and erythrocytes decreased remarkably after birth, which resulted in a significant decline in erythrocyte GSH-Px activity at 8 and 16 wk (11.2 +/- 2.0 and 11.0 +/- 1.1 U/g Hb) compared to that at birth (12.4 +/- 2.1 U/g Hb). CONCLUSION: During the early postnatal period. erythrocyte CAT and CuZn-SOD activities did not decrease in formula-fed, low-birthweight infants. Japanese commercial formula not supplemented with Se, however, caused postnatal plasma and erythrocyte Se deficiency and a concomitant decline in erythrocyte GSH-Px activity in the same subjects.

Catalase↗
PubMed2000

The C677T mutation in the methylene tetrahydrofolate reductase gene increases serum uric acid in elderly men.

A common mutation, C677T, in the methylene tetrahydrofolate reductase gene (MTHFR) reduces the activity of MTHFR and increases total homocysteine levels in plasma. Increased homocysteine levels are reportedly associated with high serum uric acid levels. The relationship between the MTHFR mutation and uric acid metabolism remains unclear, however. To investigate whether the C677T MTHFR mutation is a risk factor for hyperuricemia, we performed MTHFR genotyping and clinical laboratory determinations, including serum uric acid, in 271 elderly Japanese men (age range, 40-79 years; mean, 52.6 years). The mean uric acid levels for the C/C, C/T, and T/T genotypes were 5.67, 6.00, and 6.39 mg/dl, respectively (P = 0.012). The T/T genotype was more frequent in subjects with high uric acid levels than in those with low uric acid levels (P = 0.038). These findings suggest that the C677T MTHFR mutation contributed to higher uric acid levels in subjects enrolled in this study. In conclusion, the mutation of the MTHFR gene may be a risk factor for hyperuricemia in elderly men.

Adult↗
PubMed2000

Underexpression of neural cell adhesion molecule and neurotrophic factors in rat brain following thromboxane A(2)-induced intrauterine growth retardation.

Intrauterine growth retardation (IUGR) often results in clinical neurodevelopmental disorders. To clarify the influence of uteroplacental insufficiency on central nervous system development, we have created a model of IUGR in rats using maternal administration of synthetic thromboxane A(2). We investigated expression patterns of neural cell adhesion molecule (NCAM) and reelin in this model by semiquantitative competitive polymerase chain reactions. On postnatal day 2, NCAM expression was decreased in rat cerebral cortex, and reelin expression was decreased in hippocampus from levels in controls without maternal thromboxane exposure. No significant differences in NCAM expression were seen in hippocampus, nor did reelin expression differ in cerebral cortex between control and IUGR groups. We also examined expression of two neurotrophic factors, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). In cerebral cortex the IUGR group showed less BDNF and NT-3 expression than controls. Delay of neuronal migration and histological changes observed in our IUGR rats may be related to altered expression of these molecules.

Animals↗
PubMed2000

Abnormal cerebral neuronal migration in a rat model of intrauterine growth retardation induced by synthetic thromboxane A(2).

Many reports have associated intrauterine growth retardation (IUGR) with adverse neurological outcome, but the underlying pathology is imperfectly understood. We have developed a new rat model of IUGR using maternal administration of synthetic thromboxane A(2) (STA(2)). In the present study, the effect of this insult on neuronal migration in the rat cerebral cortex was examined. Bromodeoxyuridine (BrdU), a time-specific cell marker was administered intraperitoneally to the mothers on embryonic day (E) 19. At postnatal day (P) 3, P4, P5, and P6, pups were terminally anesthetized and brains were removed. BrdU-labeled cells were detected immunohistochemically and counted in cerebrum, which was divided into the cortical plate (CP), the intermediate zone, and the subventricular/ventricular zone (SVZ+VZ). Numbers of labeled cells in the three areas over time were compared between IUGR and control animals. Numbers of labeled cells in SVZ+VZ were significantly greater in IUGR than in controls at P3, 5, and 6 (P<0.05). In contrast, labeled cells in the CP were significantly less abundant in IUGR animals than in controls at P3, 4, and 6 (P<0.05). We concluded that neuronal migration was delayed in IUGR rats.

Animals↗
PubMed2000

Eukaryotic DNA replication: from pre-replication complex to initiation complex.

A common mechanism has emerged for the control of the initiation of eukaryotic DNA replication. The minichromosome maintenance protein complex (MCM) and Cdc45 have now been recognized as central components of the initiation machinery. In addition, two types of S phase promoting kinases conserved between yeast and humans play critical roles in the initiation reaction. At the onset of S phase, S phase kinases promote the association of Cdc45 with MCM at origins. Upon the formation of the MCM-Cdc45 complex at origins, the duplex DNA is unwound and various replication proteins, including DNA polymerases, are recruited onto unwound DNA. The increasing number of newly identified factors involved in the initiation reaction indicates that the control of initiation requires highly evolved machinery in eukaryotic cells.

Animals↗
PubMed2000

Central role for cdc45 in establishing an initiation complex of DNA replication in Xenopus egg extracts.

BACKGROUND: In eukaryotes, chromosomal DNA is licensed to be replicated through the sequential loading of the origin recognition complex, Cdc6 and mini-chromosome maintenance protein complex (MCM) onto chromatin. However, how the replication machinery is assembled onto the licensed chromatin during initiation of replication is poorly understood. RESULTS: Using Xenopus egg extracts, we have investigated the role of Cdc45 in the loading of various replication proteins onto chromatin at the onset of S phase, and found that Cdc45, which required MCM for its loading, was essential for the sequential loading of replication protein A (RPA), DNA polymerase alpha and proliferating cell nuclear antigen (PCNA) onto chromatin. The assembly of DNA polymerase epsilon onto chromatin required Cdc45 but did not require DNA polymerase alpha. Analysis of nuclease-digested chromatin fractions shows that Cdc45 formed a stable complex with either MCM or DNA polymerase alpha on chromatin. CONCLUSIONS: These results demonstrate a central role for Cdc45 in activation of the licensed chromatin to form replication complexes at the onset of S phase, and suggest that Cdc45 has a dual role in the initiation of DNA replication: the unwinding of DNA and the recruiting of DNA polymerases onto DNA.

Animals↗
PubMed1999

Acute respiratory failure associated with intrathoracic masses in neonates.

BACKGROUND: Intrathoracic masses are uncommon in children. Occasionally, they present with acute respiratory failure in the neonatal period. Although emergency resection usually is the treatment of choice, other modalities are sometimes necessary to stabilize the patient. METHODS: Seven neonates with intrathoracic masses were treated. Five had congenital cystic adenomatoid malformations (CCAM), 1 had a mediastinal teratoma, and 1 had a pneumatocele. These cases were reviewed retrospectively. RESULTS: Four of the 7 infants had respiratory failure in the neonatal period. A patient with a large mediastinal teratoma and 1 with a CCAM that increased rapidly after presentation underwent emergency operation, relieving respiratory distress. The other 2 large CCAMs presented with severe respiratory distress immediately after birth because of pulmonary hypoplasia. One neonate with a Stocker-I CCAM died after emergency resection. One more recent patient with a Stocker-III CCAM survived after successful treatment with delayed resection, performed 3 days after birth. Nitric oxide (NO), and extracorporeal membrane oxygenation (ECMO) were instituted as supportive care because of profound persistent fetal circulation (PFC). CONCLUSIONS: Acute respiratory failure associated with intrathoracic masses in neonates may be managed in 1 of 2 ways. A small mass that increases rapidly should be resected soon after presentation. In neonates with large masses with associated PFC, surgery can be delayed until the patient is stable. ECMO, NO, and high-frequency oscillation (HFO) can be used aggressively for stabilizing such neonates.

Extracorporeal Membrane Oxygenation↗
PubMed1999

Neuropathological changes in the cerebrum of IUGR rat induced by synthetic thromboxane A2.

IUGR was induced by maternal administration of synthetic thromboxane A2 (STA2) from the 13th day of gestation. Fetuses and neonates showed a markedly significant weight reduction. In E16 IUGR brain, no pathological abnormalities were found, but morphological changes appeared in the cortical plate of E18 IUGR brain. In E20 IUGR brain, ectopic clusters of differentiating cells cytologically mimicking neuroblasts were found in the neuroepithelial layer, but these abnormal clusters of cells in IUGR brain of late gestation were never observed in PN7. Morphometric analysis of coronal-sectional areas of the brain and cortical plate demonstrated that there were no differences between IUGR rats and controls in E16 and E18. These areas were, however, significantly reduced in E20 and PN7 growth-retarded rats compared with the control. Because the period of STA2 administration coincides with the neuro-developmental stage of cell migration and differentiation, reduction of the uteroplacental blood supply might cause a transient abnormal cytoarchitecture of the cerebral cortex resulting in brain growth retardation.

Animals↗
PubMed1999

Depression of the xylanase-encoding cgxA gene of Chaetomium gracile in Aspergillus nidulans.

Regulation of the Chaetomium gracile xylanase A gene (cgxA) was investigated using Aspergillus nidulans as an intermediate host. Deletion of a 185 bp DNA fragment from its promoter region led to higher levels of the cgxA gene expression, indicating that the 185 bp DNA fragment contains an element involved in repression of the gene. A nuclear extract was assayed for proteins which bind to the 185 bp DNA fragment. A protein designated AnRP bound sequence specifically to the DNA fragment. The minimum sequence required for AnRP binding, 5'TTGACAAAT-3', was determined by means of gel mobility shift assays with various double-stranded oligonucleotides. Furthermore, this sequence repressed the expression of the cgxA gene when inserted at the 5' end of the cgxA gene on pXAH, which was deleted for the repressive element from the promoter region.

Amino Acid Sequence↗
PubMed1999

Twin-to-twin transfusion syndrome with hydrops: a retrospective analysis of ten cases.

We retrospectively studied 10 cases of twin-to-twin transfusion syndrome (TTTS) with fetal hydrops. TTTS was diagnosed sonographically between the 17-31 weeks of gestation. All twins were delivered by emergency cesarean section because of cardiac decompensation of one or both fetuses. The mean (+/-SD) age at diagnosis was 26.1 +/- 4.5 and the mean age at delivery was 28.8 +/- 2.0 weeks. Gestational age at birth was similar in survivors and nonsurvivors. However, surviving infants were diagnosed later in gestation (23.6 +/- 4.8 vs. 28.7 +/- 1.9 weeks; p < 0.01); and gestational age at appearance of hydrops were later in survivors (26.1 +/- 3.2 vs. 29.2 +/- 2.4 weeks; p < 0.05). Overall survival rate was 50% (10 of 20 infants). All survivors were delivered within 3 days after the appearance of fetal hydropic changes. Extrauterine treatment in earlier stages of TTTS might improve the outcome. Nevertheless, more aggressive intrauterine treatment should be considered in the most severe cases of TTTS developing before 24-25 weeks' gestation.

Cesarean Section↗
PubMed1998

Xenopus Cdc45-dependent loading of DNA polymerase alpha onto chromatin under the control of S-phase Cdk.

At the onset of S phase, chromosomal replication is initiated by the loading of DNA polymerase alpha onto replication origins. However, the molecular mechanisms for controlling the initiation are poorly understood. Using Xenopus egg extract, we report here the identification of a Xenopus homolog of Cdc45, a yeast protein essential for the initiation of replication, which is shown to be an essential molecule for the initiation of replication via the loading of DNA polymerase alpha onto chromatin. XCdc45, by physically interacting with the polymerase in the extract, became associated with chromatin only after nuclear formation. During S phase, XCdc45 co-localized with the polymerase in the nuclei, and the loading of the polymerase, which depended on endogenous XCdc45, was facilitated by exogenously added recombinant XCdc45. These findings, together with the apparent requirement of S-phase-cdk activity for the loading of XCdc45, suggest that XCdc45, under the control of S-phase cdk, plays a pivotal role in the loading of DNA polymerase alpha onto chromatin.

Animals↗
PubMed1998

cDNA cloning and expression during development of Drosophila melanogaster MCM3, MCM6 and MCM7.

cDNAs encoding three Drosophila melanogaster MCM proteins, DmMCM3, DmMCM6 and DmMCM7, candidates of DNA replication-licensing factors, were cloned and sequenced. The deduced amino-acid sequences displayed 60, 59 and 68% identities with the respective Xenopus laevis homologues, XMCM3, XMCM6 and XMCM7. Six members of the D. melanogaster MCM family were found to share 31-36% identities in their amino-acid sequences, and to possess the five common domains carrying conserved amino-acid sequences as reported with X. laevis MCM proteins. DmMCM3, DmMCM6 and DmMCM7 genes were mapped to the 4F region on the X chromosome, the 6B region on the X chromosome and the 66E region on the third chromosome, respectively, by in situ hybridization. Contents of their mRNAs were proved to be high in unfertilized eggs and early embryos (0-4h after fertilization), then decrease gradually by the 12h time point, with only low levels detected at later stages of development except in adult females. This fluctuation pattern is similar to those of genes for proteins involved in DNA replication, such as DNA polymerase alpha and proliferating cell nuclear antigen, suggesting that expression of DmMCM genes is under the regulatory mechanism which regulates expression of other genes involved in DNA replication.

Amino Acid Sequence↗