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Biomedical subjects

M Kawata

Publications and source records attributed to M Kawata.

At least 37 records · Page 2Linked to original sources
PubMed2001

A new glucose-6-phosphate dehydrogenase variant G6PD Sugao (826C-->T) exhibiting chronic hemolytic anemia with episodes of hemolytic crisis immediately after birth.

A case of glucose-6-phosphate dehydrogenase (G6PD) deficiency associated with chronic hemolysis with episodes of hemolytic crisis immediately after birth is reported. The propositus was a 1-month-old Japanese male infant. Molecular analysis of the G6PD gene revealed a novel missense mutation (826C-->4T) in exon 8 predicting a single amino acid substitution, Pro276Ser. The mother was confirmed to be heterozygous for this mutation. We designated this novel class 1 variant as G6PD Sugao. Pro276 is a phylogenetically conserved residue that may play a significant role in dimer formation.

Anemia, Hemolytic, Congenital↗
PubMed2001

Intracellular dynamics of steroid hormone receptor.

Steroid hormones substantially influence brain development, reproduction sexual differentiation and emotion. These effects are mediated by steroid hormone receptors and cofactors, which directly regulate gene expression. Deciphering how and where these transcriptional activators occur in a cell provides the groundwork for elucidating the influence of these small hydrophobic signal molecules on various brain functions. This paper describes some of the recent investigations into the subcellular localization of steroid hormone receptors and cofactors using GFPs and other immunocytochemical methods.

Animals↗
PubMed2001

Serotonergic neurones in the dorsal raphe nucleus that project into the medial preoptic area contain oestrogen receptor beta.

Serotonin is involved in female sexual behaviour in which the medial preoptic area (MPA) has a pivotal role. The present study used immunohistochemistry, in situ hybridization and retrograde transport analysis to investigate whether serotonin neurones in the dorsal raphe nucleus (DRN) of females projecting into the MPA contained oestrogen receptor alpha or beta. The projection of serotonin neurones from the DRN to the MPA was confirmed using the microinjection of Fluoro-Gold (FG), a fluorescent retrograde tracer, into the MPA of ovariectomized (OVX-group) and OVX-rats treated with oestradiol benzoate (E2-group). A number of serotonin neurones in the DRN were labelled with FG, indicating that these serotonin neurones in DRN project their terminals into the MPA. FG-labelled serotonin neurones expressed ERbeta mRNA in the DRN, and the number of the serotonin neurones containing ERbeta mRNA between the OVX-group and the E2-treated group was not significantly different. Serotonin neurones in the DRN did not express ERalpha-immunoreactivity. Since previous findings showed that the density of serotonin-immunoreactive fibres and the concentration of serotonin within the MPA was significantly lower in the E2-group than the OVX-group, our present observations suggested that the regulatory effects of E2 on the serotonergic neurone system in the MPA may be via ERbeta within the serotonin-containing cells in the DRN of female rats.

Animals↗
PubMed2001

Balloon catheter-assisted endoscopic sclerotherapy for gastric fundal varices using alpha-cyanoacrylate monomer.

We present two patients with bleeding episodes from gastric fundal varices. The gastric fundal varices were treated by balloon catheter-assisted endoscopic sclerotherapy using alpha-cyanoacrylate monomer. The varices were successfully obliterated with no complications or hemodynamic changes to the gastrorenal shunts. This procedure may be considered a novel, feasible approach to the treatment of gastric fundal varices in the future.

Aged↗
PubMed2001

Dynamic changes in subcellular localization of mineralocorticoid receptor in living cells: in comparison with glucocorticoid receptor using dual-color labeling with green fluorescent protein spectral variants.

Mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) are ligand-dependent transcription factors. Although it is generally accepted that GR is translocated into the nucleus from the cytoplasm only after ligand binding, the subcellular localization of MR is still quite controversial. We examined the intracellular trafficking of MR in living neurons and nonneural cells using a fusion protein of green fluorescent protein (GFP) and rat MR (GFP-MR). Corticosterone (CORT) induced a rapid nuclear accumulation of GFP-MR, whereas in the absence of ligand, GFP-MR was distributed in both cytoplasm and nucleus in the majority of transfected cells. Given the differential action of MR and GR in the central nervous system, it is important to elucidate how the trafficking of these receptors between cytoplasm and nucleus is regulated by ligand. To examine the simultaneous trafficking of MR and GR within single living cells, we use different spectral variants of GFP, yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP), linked to MR and GR, respectively. In COS-1 cells, expressing no endogenous corticosteroid receptors, the YFP-MR chimera was accumulated in the nucleus faster than the CFP-GR chimera in the presence of 10(-9) M CORT, while there was no significant difference in the nuclear accumulation rates in the presence of 10(-6) M CORT. On the other hand, in primary cultured hippocampal neurons expressing endogenous receptors, the nuclear accumulation rates of the YFP-MR chimera and CFP-GR chimera were nearly the same in the presence of both concentrations of CORT. These results suggest that CORT-induced nuclear translocation of MR and GR exhibits differential patterns depending on ligand concentrations or cell types.

Animals↗
PubMed2001

Subcellular steroid/nuclear receptor dynamics.

Steroid hormones, thyroid hormones, retinoic acids, and vitamin D bind to their receptors, which are now called steroid/nuclear receptors, and liganded receptors translocate either intracellularly or intranuclearly and form large protein complexes with cofactors to induce or repress gene transcription. Therefore, steroid/nuclear receptors are ligand-dependent transcription factors. With the advent of green fluorescent protein (GFP) and its color variants, the subcellular distribution of many steroid/nuclear receptors has been found to be much more dynamic than previously thought, with some of the receptors shuttling between the cytoplasm and nucleus. Steroid/nuclear receptors can be divided into three categories based on their unliganded distribution: those that are primarily in the nucleus, those in the cytoplasm, and those with mixed cytoplasmic and nuclear distributions. However, in all cases, the addition of a ligand leads to almost complete nuclear translocation of the receptors. Hormonal stimulation induces intranuclear receptor distribution from a homogeneous pattern to a heterogeneous dot-like image. Ligand binding to steroid/nuclear receptors leads to the recruitment of many proteins including cofactors to provoke the redistribution of receptor complexes in the nucleus. This focal organization could involve more complex events than simple DNA binding sites for transcription. Protein activities and interactions of steroid/nuclear receptors can be imaged and localized in a single cell.

Animals↗
PubMed2001

The angiotensin-I-converting enzyme inhibitor perindopril suppresses tumor growth and angiogenesis: possible role of the vascular endothelial growth factor.

Angiotensin-I converting enzyme (ACE) inhibitor is used widely as an antihypertensive agent, and it has been suggested recently that it decreases the risk of cancer (A. F. Lever et al., Lancet, 352: 179-184, 1998). In this study, we examined the effect of several ACE inhibitors and angiotensin-II type 1 receptor (AT(1)-R) antagonists on tumor development and angiogenesis in a murine hepatocellular carcinoma model. Among ACE inhibitors, perindopril appeared to be a potent inhibitor of tumor development and angiogenesis, whereas AT(1)-R antagonists did not exert such an inhibitory effect. The inhibitory effect of perindopril was achieved even on established tumors. The level of the potent angiogenic factor, vascular endothelial growth factor (VEGF), in the tumor was significantly suppressed by perindopril. In vitro studies showed that perindopril-derived active form, perindoprilat, suppressed the endothelial cell tubule formation. Perindoprilat treatment also significantly inhibited VEGF mRNA expression in BNL-HCC cells in vitro. These results showed that the ACE inhibitor perindopril inhibited tumor development and angiogenesis independent from AT(1)-R blockage, and that VEGF alternation may be involved in the mechanism of this inhibitory effect. Because perindopril is widely used in clinical practice, it may represent an effective new strategy for anticancer therapy.

Angiotensin Receptor Antagonists↗
PubMed2001

Left ventricular apex venting during deep hypothermia in a case of difficult re-entry into the mediastinum.

The cardiopulmonary bypass techniques of peripheral cannulations and deep hypothermia provide safe and controlled re-entry into the mediastinum, when the thoracic organs are contiguous with the sternum. In such cases, in order to prevent ventricular distention during cooling, left ventricular venting is very important but can be difficult. We made a small (3 cm) left-sided thoracotomy incision and inserted a left ventricular apical venting tube while cooling a patient with a large pseudoaneurysm of the ascending aorta, which was diagnosed 12 years after aortic valve replacement. We found that this technique was easy, safe, and useful to prevent ventricular distention during cooling.

Aneurysm, False↗
PubMed2000

Characterization of spontaneous mutation in the oxyR strain of Escherichia coli.

Escherichia coli K-12 strain EY5, deficient in oxyR, was constructed to assess the role of oxyR and oxyR-regulated regulon in spontaneous mutagenesis. Mutagenesis was monitored by selecting two forward mutations of colicin B-sensitive to resistance and valine-sensitive to resistance, one base substitution mutation of rifampicin-sensitive to resistance and one reversion of argE3 his-4 to Arg(+) His(+). Deficiency of oxyR did not lead to the enhancement of spontaneous mutation frequencies of the four markers tested. By DNA sequence analysis, we determined 49 colicin B-resistant mutants derived from EY5 and found that 37% were base substitutions, 29% IS element insertions, 20% deletions, and 14% single base frameshifts. Among the base substitutions, G:C-->T:A transversions predominated followed by G:C-->A:T transitions and A:T-->T:A transversions. These spectra were essentially the same as those from oxyR(+) strains. The results indicate that oxyR and oxyR-regulated genes do not play a significant role in the defense against spontaneous mutagenesis.

Bacterial Proteins↗
PubMed2000

Immunohistochemical study of nucleoporin p62 in the hippocampus and hypothalamus of the rat brain.

We immunohistochemically studied the distribution of nucleoporin p62 in the hippocampus and hypothalamus of rat brain. Previous reports have shown the presence of p62-immunoreactivity (ir) in the nuclear rim in the non-neuronal cells, but the present study showed that of p62-ir within the nucleus in addition to the nuclear rim in the neuronal cells of the hippocampus and hypothalamic nuclei; in these areas the glucocorticoid receptor (GR) undergoes nucleocytoplasmic translocation determined by ligand. We analyzed the expression of p62-ir after adrenalectomy (ADX). ADX changed the localization of GR-ir from the nucleus to the cytoplasm, but did not change the localization or immunoreactivity of p62, suggesting that nucleoporin p62 is stable regardless of intracellular signal transduction between the cytoplasm and the nucleus.

Animals↗
PubMed2000

Trophic interactions between brain-derived neurotrophic factor and s100beta on cultured serotonergic neurons.

Brain-derived neurotrophic factor (BDNF) and S100beta stimulate serotonergic neurons in fetal rat raphe primary cultures grown under serum-free conditions. BDNF (50 ng/ml) treatment for 3 h enhanced S100beta immunoreactivity in both raphe and hippocampal glial cells. Combined treatment with BDNF and S100beta for 3 days increased the soma area of 5-HT neurons, but not the neurite length. Our results suggest that BDNF and S100beta, which regulate different signal transduction cascades, interact to exert complimentary effects on neuronal maturation by acting sequentially, not concurrently.

Animals↗
PubMed2000

In vitro and in vivo immunocytochemistry for the distribution of mineralocorticoid receptor with the use of specific antibody.

To examine the distribution of mineralocorticoid receptor (MR) and the interactions with glucocorticoid receptor (GR) in the brain, we raised a polyclonal antibody against the transcriptional modulation domain of rat MR using the GST-fusion system. Immunoblotting analysis revealed that this antibody recognized a band with the molecular mass of MR in MR-transfected COS-1 cells and in a homogenate of rat hippocampus, and showed no cross-reactivity with GR. In vitro immunocytochemistry of both primary cultured hippocampal neurons and MR-transfected cells revealed immunoreactivity detected by this antibody in both the cytoplasm and nucleus in the absence of aldosterone (ALD), a specific agonist of MR. After 1 h of treatment with 10(-7) M ALD, the MR-immunoreactivity was accumulated in the nuclear region. In the case of GR-transfected cells, our anti-MR antibody either detected no immunopositive cells in the presence or absence of GR agonist. In our in vivo study, MR-immunoreactivity was observed in the rat hippocampus, where cell nuclei showed immunopositive reactions. These results suggest that our antibody against rat MR shows high specificity for the receptor both in liganded and unliganded forms, with no cross-reactivity to GR, and will be useful for cell biological and neuroanatomical investigations of MR.

Aldosterone↗
PubMed2000

The distributions of apoptotic cells in the medial preoptic areas of male and female neonatal rats.

The medial preoptic area (MPA) of the hypothalamus of the rat contains two sexually dimorphic nuclei, the periventricular preoptic nucleus (PVpo) and the medial preoptic nucleus (MPN). To examine the relationship between sexual dimorphism and neuronal death, we examined the number of apoptotic cells in the subdivisions of the MPA in neonatal rats of postnatal days 1 (P1), 4 (P4), 7 (P7) and 14 (P14). Apoptotic cells in these areas were classified according to their progression into three stages. P1 and P4 rats contained many apoptotic cells in the subfield along the third ventricle, including the PVpo, and their number was significantly larger in P1 males: in particular, the number of early-stage cells was larger in males than females. The number of apoptotic cells in the MPN was increased in P4 and P7 rats, although no significant sexual differences were seen in the total number or in the number of each progressive stage of apoptotic cells. In P14 rats, very few apoptotic cells were seen in the MPA. Our data revealed that the distribution of apoptotic cells in the MPA of developing rats depends on the sexuality, subdivision of the area and postnatal period.

Animals↗
PubMed2000

Tissue inhibitor of metalloproteinases-1 promotes liver fibrosis development in a transgenic mouse model.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) has been shown to be increased in liver fibrosis development both in murine experimental models and human samples. However, the direct role of TIMP-1 during liver fibrosis development has not been defined. To address this issue, we developed transgenic mice overexpressing human TIMP-1 (hTIMP-1) in the liver under control of the albumin promoter/ enhancer. A model of CCl(4)-induced hepatic fibrosis was used to assess the extent of fibrosis development in TIMP-1 transgenic (TIMP-Tg) mice and control hybrid (Cont) mice. Without any treatment, overexpression of TIMP-1 itself did not induce liver fibrosis. There were no significant differences of pro-(alpha1)-collagen-I, (alpha2)-collagen-IV, and alpha-smooth muscle actin (alpha-SMA) mRNA expression in the liver between TIMP-Tg and Cont-mice, suggesting that overexpression of TIMP-1 itself did not cause hepatic stellate cell (HSC) activation. After 4-week treatment with CCl(4), however, densitometric analysis revealed that TIMP-Tg-mice had a seven-fold increase in liver fibrosis compared with the Cont-mice. The hepatic hydroxyproline content and serum hyaluronic acid were also significantly increased in TIMP-Tg-mice, whereas CCl(4)-induced liver dysfunction was not altered. An active form of matrix metalloproteinases-2 (MMP-2) level in the liver of TIMP-Tg-mice was decreased relative to that in Cont-mice because of the transgenic TIMP-1. Immunohistochemical analysis revealed that collagen-I and collagen-IV accumulation was markedly increased in the liver of CCl(4)-treated TIMP-Tg-mice with a pattern similar to that of alpha-SMA positive cells. These results suggest that TIMP-1 does not by itself result in liver fibrosis, but strongly promotes liver fibrosis development.

Actins↗
PubMed2000

Magnetic resonance angiography for monitoring prophylactic endoscopic treatment of high risk esophageal varices.

BACKGROUND AND STUDY AIMS: Endoscopic injection sclerotherapy (EIS) and endoscopic variceal ligation (EVL) are used worldwide as the treatment for esophageal varices. We evaluated portal hemodynamics using magnetic resonance angiography (MRA) in these two forms of treatment. PATIENTS AND METHODS: The study was carried out in 50 cirrhotic patients. MRA was performed to identify the hepatofugal supply vein selectively for esophageal varices. Those who showed a positive MR angiogram for the supply vein were randomly allocated to one of two groups, using the sealed envelope method, and underwent either EIS or EVL. On the other hand, those with a negative angiogram received only EVL. EIS was done to embolize esophageal varices as well as their feeders by intravariceal injection of sclerosant under fluoroscopic guidance. RESULTS: A positive MR angiogram of the hepatofugal left gastric vein as the supply vein was observed in 41 patients. Nine patients showed negative MRA results. Among those with positive angiograms, the rate of eradication of the left gastric vein was higher in the EIS-treated group than in the EVL treated group (50% vs. 8.6%). After either treatment, the recurrence-free rate for high risk esophageal varices was higher in patients with complete eradication of the left gastric vein than in those without (88% vs. 35%). In patients with negative angiogram results, who only underwent EVL, high risk esophageal varices did not reappear over a long period. CONCLUSION: MRA is useful for evaluating portal hemodynamics. With the aim of avoiding recurrence of esophageal varices, EIS was suitable for patients who had a hepatofugal supply vein for the varices because recurrence could be prevented by embolization of the supply vein. EVL may be expected to be efficacious in patients where no image of a hepatofugal supply vein is found on MRA.

Adult↗
PubMed2000

Ampulla cardiomyopathy ('Takotusbo' cardiomyopathy)--reversible left ventricular dysfunction: with ST segment elevation.

The clinicopathologic findings of reversible ampulla-like ventriculogram of the left ventricle were studied in 8 elderly women and one middle-aged man. Their coronary arteriograms were normal, even in the 7 patients who had ST elevation on electrocardiogram. Coronary spasm was positive in only 2 of the 7 patients who received provocation tests. Biopsy specimens revealed focal myocyte injury. Normal coronary arteriograms during ST elevation and the presence of pathologic myocardial lesions were not consistent with a concept of stunned myocardium. The presence of myocardial lesions suggested that focal and disseminated myocardial damage had occurred.

Aged↗
PubMed2000

Endothelial nitric oxide synthase gene mutation and human leukocyte antigen analyzed in three cases of familial vasospastic angina pectoris.

A 50-year-old woman with rest angina underwent cardiac catheterization; coronary angiography in the presence of acetylcholine revealed 99% coronary spasm of the proximal left anterior descending artery. The patient's 82-year-old mother was also admitted to hospital with rest angina. Her Holter electrocardiogram showed ST-segment elevation during the attack at rest and coronary angiography showed 99% spasm of the right coronary artery and 90% spasm of the left coronary artery. Both women complained of chest pain during the spasm, which was accompanied by ST-segment depression. The 62-year-old brother of the original patient was also found to have coronary spasm of the left coronary artery. Human leukocyte antigen was analyzed in the 2 women: A2, B51, CW1, DR8 and DQ1 were common factors. A Glu298Asp point mutation of the endothelial nitric oxide synthase gene was investigated in both parents, their 2 daughters and 2 sons, but was not detected in the 3 patients, and was detected only in the 90-year-old father who did not suffer from angina. Nor was the T-786-C mutation found in the 3 cases. Other causes of familial spasm need to be elucidated.

Aged↗