Search PubMed⌕ Search

Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 361 records · Page 20Linked to original sources
PubMed1998

Ambulatory blood pressure normality: experience in the Ohasama Study.

OBJECTIVE: To define the reference values of ambulatory blood pressure (APB) using results from the Ohasama study. RESULTS: The distribution criteria of 24 h ABP for the total population of Ohasama were 135/79 (mean + SD), 148/86 (mean + SD), and 146/85 mmHg (95th percentile), and those for normotensive subjects were 129/76 (mean + SD), 142/85 (mean + 2 SD) and 139/81 mmHg (95th percentile). The corresponding criteria [i.e. the 24 h ABP corresponding to 140/90 and 160/95 mmHg casual (clinical) blood pressure of the total population] were 125/76 and 132/76 mmHg. A long-term prospective study based on cardiovascular morbidity and mortality would provide the most meaningful values. For the prognostic criteria, based on nonparametric analysis, the hypertensive range of the 24 h ABP was postulated to be >/= 134/>/= 78 mmHg, whereas that based on parametric analysis was postulated to be >/= 134/ 79 mmHg. The lowest relative hazard was observed at 128/74 mmHg in parametric analysis. Thus, we tentatively propose reference values>/= 135/>/= 80 mmHg for hypertensive 24 ABP and < 125/< 75 mmHg for normotensive 24 h ABP.CONCLUSION:

Journal Article↗
PubMed1998

Activation of protein phosphatase 1alpha promoter in ascites hepatoma cells.

We have already reported the nucleotide sequence of 5'-flanking region of rat PP1alpha gene and identified the promoter region in NIH3T3 cells. Here we determined the promoter activity of PP1alpha gene in ascites hepatoma cells and compared with that of hepatocytes. Reporter analysis showed that the promoter activity was enhanced in an ascites hepatoma AH13 compared with normal hepatocytes at two regions, -37 to -198 bp and -492 to -848 bp upstream of the translation start site. At -37 to -198 bp region with high GC content, binding of Sp1 was markedly increased in all of five ascites hepatomas examined. At -492 to -848 bp region, two bands were clearly detected in two of the five ascites hepatomas, AH13 and AH7974F, by gel shift analysis. These results strongly suggest that the increase in PP1alpha mRNA expression in ascites hepatomas is at least in part due to the enhanced promoter activity of PP1alpha gene.

Animals↗
PubMed1998

[Catheter intervention for adult congenital heart diseases].

The efficacy of catheter intervention for adult congenital heart diseases was evaluated in 27 patients aged 20 to 52 years (mean age at catheterization 25 +/- 7 years) from 1986 to 1996. Four patients had pulmonary valve stenosis, four had aortic valve stenosis, three had coarctation of the aorta, 10 had pulmonary artery stenosis, four had cyanotic heart diseases and aorto-pulmonary collateral arteries, one had patent ductus arteriosus, and one had cyanotic heart disease and stenotic Blalock-Taussig shunt. Balloon dilation was successful in all patients with pulmonary valve stenosis, and follow-up evaluation (1-8 years) showed no restenosis in any patients. Balloon dilation was successful in all patients with aortic valve stenosis, and follow-up evaluation (0.5-5 years) showed transvalvular pressure gradient < 50 mmHg. Stenosis was relieved successfully in all patients with coarctation of the aorta, and follow-up evaluation showed no restenosis. Balloon dilation was successful in eight of 13 locations (62%) in patients with pulmonary artery stenosis. Coil embolization was successful in all patients with cyanotic heart diseases and aortopulmonary collateral arteries. In a patient with patent ductus arteriosus, two coils were placed in the ductus arteriosus but were retrieved because hemolysis was observed after the embolization. These data indicate that catheter intervention in young adults with congenital heart diseases is as effective as in children.

Adult↗
PubMed1998

[Ebstein's anomaly associated with left ventricular dysfunction: a case report].

A 66-year-old man presented with Ebstein's anomaly associated with left ventricular dysfunction. He had been followed since 40 years of age for cardiomegaly and arrhythmia, and experienced episodes of orthopnea at the age of 64. He was referred to our hospital in April 1997 because of lower extremity edema. Physical examination revealed dilated external jugular vein, tenderness of the right hypocondorium, and lower extremity edema. Electrocardiography confirmed atrial fibrillation. Transthoracic echocardiography revealed bilateral atrial and ventricular dilation, and paradoxical septal movement. The apical four-chamber view demonstrated 15 mm apical displacement of the septal leaflet. Color Doppler echocardiography revealed moderate tricuspid regurgitation. Transesophageal echocardiography revealed low echoic and hypoplastic tricuspid valve. Left ventriculography showed diffuse hypokinesis, and the ejection fraction was 49%. The coronary artery was normal. Atrial septal defect was not detected. Diffuse fibrosis, which may be found in the hearts of patients with Ebstein's anomaly at autopsy may have been responsible for the left ventricular depressed systolic function in this patient.

Aged↗
PubMed1998

Allogeneic peripheral blood stem cell transplantation for standard-risk leukemia. A multicenter pilot study: Japanese experience. Japan Blood Cell Transplantation Study Group.

A multicenter phase II study of allogeneic peripheral blood stem cell transplantation (allo-PBSCT) was conducted. Twenty-two patients (median age, 36 years) with standard-risk leukemia were transplanted with G-CSF-mobilized PBSC from an HLA-identical sibling donor, and received cyclosporine and methotrexate for GVHD prevention. Median days to ANC >500/microl and platelets >50,000/microl were 12 (9-20) and 16 (11-32), respectively. Grade II-IV acute GVHD developed in 6/21 (29%) and extensive chronic GVHD in 12/20 (60%). These observations indicate that allo-PBSCT is characterized by rapid hematologic engraftment, no increase of acute GVHD and an increased risk of chronic GVHD, and can be used as an alternative to allogeneic bone marrow transplantation.

Adolescent↗
PubMed1998

[A case of air embolism during tubal insufflation].

Air embolism occurred immediately after tubal insufflation in a 40-yr-old female patient following abdominal total hysterectomy under general anesthesia. Abrupt decreases in Etco2, Spo2, and blood pressure were observed. Blood gas analysis revealed a marked difference between PaCO2 and EtCO2. The patient recovered soon and was extubated in the operating room. The post operative course was uneventful. Monitoring of EtCO2 was effective for early detection of air embolism.

Adult↗
PubMed1998

Induction of donor-specific tolerance to cardiac xenografts in utero.

BACKGROUND: Problems associated with heart transplantation, such as shortage of suitable organs and the side effects of immunosuppressive therapy, are especially serious for patients in the pediatric age group. Induction of donor-specific immunologic tolerance without immunosuppressive drugs would be ideal for clinical organ transplantation. In this study, we used a vascularized cardiac xenograft model to achieve donor-specific unresponsiveness without immunosuppression by manipulating the intrauterine immune response. METHODS: Lewis rats and Golden Syrian hamsters were used as the recipients and donors, respectively. Donor bone marrow cells (15 x 10(6) in 0.05 mL) were injected into each fetus of pregnant Lewis rats on days 9 (n = 2) and 16 (n = 2) of gestation. Donor hearts were heterotopically transplanted into each surviving (n = 8, n = 5) fetus of the Lewis rats at 8 weeks of age. Donor hearts were also transplanted into untreated rats as controls (n = 8). RESULTS: The mean cardiac xenograft survival time was 2.5 +/- 0.5, 7.4 +/- 4.1, and 2.8 +/- 0.8 days in the control group, gestational day 9 group, and gestational day 16 group, respectively. Chromosomal analysis of the day 9 group showed Golden Syrian hamster chromosomes as well as Lewis rat chromosomes. CONCLUSIONS: Cardiac xenograft survival was significantly prolonged by intrauterine exposure to xenograft bone marrow cells on day 9 but not on day 16 of gestation. Cardiac xenograft survival and chromosomal analysis of the recipient bone marrow suggested that chimerism was achieved between Golden Syrian hamsters and Lewis rats. Cardiac xenotransplantation may be possible by induction of donor-specific tolerance in utero.

Animals↗
PubMed1998

[An autopsy case of intravascular malignant lymphomatosis with hemophagocytic syndrome, mental confusion and liver dysfunction].

A 66-year-old Japanese man was admitted to Hitachi General Hospital because of fatigue, fever, edema, and icterus. A blood examination showed anemia, leukocytosis, and hyperbilirubinemia. Antibiotics did not alleviate the inflammatory symptoms. On the 13th hospital day, the patient demonstrated mental confusion, with progressive anemia and thrombocytopenia. Bone marrow aspiration revealed an increase of macrophages showing erythrophagocytosis. A diagnosis of hemophagocytic syndrome was made, but no viral infection or hematological malignancy could be detected. The patient was treated with gamma-globulin and methylprednisolone for hemophagocytic syndrome, but died of respiratory insufficiency with progressive hyperbilirubinemia and trombocytopenia on the 29th hospital day, A postmortem examination showed proliferation of lymphoma cells within the small blood vessels of the brain, lungs, liver, and many other organs, but the bone marrow was not involved. An immunohistochemical examination resulted in a diagnosis of intravascular malignant lymphomatosis (IML) of B cell origin. No viral infection was detected with in situ hybridization methods. Although IML occasionally accompanies thrombocytopenia, infiltration of lymphoma cells in the bone marrow is rare. Lymphoma associated hemophagocytic syndrome may cause cytopenia in some patients with IML, as indicated in this case.

Aged↗
PubMed1998

[Radiologic features of superficial-type hyperplastic polyps in the large intestine].

We studied 38 superficial-type hyperplastic polyps of more than 0.6 cm in size on radiographs to examine their morphologic features. The 38 lesions ranged in size from 0.6 cm to 2.5 cm, and 22 were located in the sigmoid and transverse colon (Table 1, Fig.1). The cross-section and surface configurations of the 38 lesions studied radiographically are illustrated in Fig. 2. 24 lesions without central depression were classified into 5 groups (1-a to 1-e). The 14 other lesions had central depression (2-a). The cross-section configuration was sharp in all lesions, and a finely serrated arrangement was seen in 30 of them. In surface configuration, several granular patterns were seen, but full-blown undulated folds and/or regular granular patterns were characteristic in groups 1-c, 1-d and 2-a. These radiologic features of cross-section and surface configuration may be regarded as a possible means of distinguishing superficial-type hyperplastic polyps from adenomas and carcinomas of the large intestine.

Adult↗
PubMed1998

Inhibition of salivary fluid secretion by occlusion of the intercellular space.

The effects of HCO3- on fluid secretory rate, cell volume and tissue structure were studied in perfused submandibular salivary glands under hyposmotic conditions (240 mosM). Fluid secretion was elicited by acetylcholine (ACh) in a hyposmotic HCO3(-)-free solution. Upon switching the perfusate from the HCO3(-)-free to the HCO3(-)-containing solution during ACh stimulation, the fluid secretory rate exhibited a small transient increase followed by a sharp decrease. ACh stimulation evoked rapid cell shrinkage in the absence of HCO3-, but upon switching from the HCO3(-)-free to the HCO3(-)-containing solution during ACh stimulation, the acinar cells exhibited increases in volume. In laser confocal microscopic examination of isolated acini, fluorescence of lucifer yellow was detected in the lateral intercellular spaces during ACh stimulation in the absence of HCO3-, but not in the presence of HCO3-. Electron microscopic examination revealed similar findings. We propose that the occlusion of the lateral intercellular space induced by cell swelling may result in an increase in the resistance to fluid flow in the space and consequently a decrease in the fluid secretion rate. Maintenance of an open lateral intercellular space may be an important requirement for fluid secretion. These observations suggest that a paracellular pathway may play a significant role in salivary fluid secretion.

Acetylcholine↗
PubMed1998

Pathological and histological study on retinoblastoma.

We studied 30 cases of retinoblastoma (Rb) pathologically and histochemically. Rb cases were classified into two types, 18 cases of differentiated (D-type) and 12 undifferentiated type (U-type) according to International Classification of Diseases for Oncology(1990, WHO). D-type of Rb is found more commonly in younger infants less than 1 year, but U-type found more frequently in aged infants from 2 to 4 years. D-type Rb showed more marked necrotic areas, degeneration and calcification. Immunohistochemical stains were carried out in 21 cases of Rb by use of MIB-1, PCNA, bcl-2, Fas, BAX, NF, SP and Tunel stains, respectively. MIB-1 is a good marker of proliferation of Rb cells and its high positivity correlates closely to more extensive necrotic areas of Rb cases. There are only a few positive cells by Tunel stain suggesting apoptotic cells, but diffuse positive cells by bcl-2 and Fas and completely negative by BAX gene. From these results, it can be seen that differentiation of Rb cells may be affected by bcl-2 and Fas but not by BAX gene.

Age Factors↗
PubMed1998

Expression and localization of the urokinase-type plasminogen activator receptor (uPAR) in the human placenta.

In pregnancy the decrease in fibrinolytic activity has been described to date by many researchers. The placenta is a source of both plasminogen activator inhibitor type 2 (PAI-2) and type 1 (PAI-1). The PAI-2 was originally detected in the human placenta, which inhibits urokinase-type plasminogen activator (uPA) while it is unable to inhibit tissue type plasminogen activator (tPA). The urokinase-type plasminogen (uP) is activated by u-PA and urokinase-type plasminogen activator receptor (uPAR). We studied the expression and the localization of u-PAR in the human placenta by in situ hybridization, immunohistochemically and by use of Northern blot analysis. These data show that the decidualized endometorium have the cells with the greatest uPAR mRNA expression in the placenta, and syncytiotrophoblasts express lower level of uPAR mRNA.

Adolescent↗
PubMed1997

Expression of cytokine receptors on follicular dendritic cells.

Follicular dendritic cells (FDCs) in the lymphoid follicle (LF) are essential to the sequential processes of B-cell proliferation, selection, and differentiation. Although the importance of some cytokines in these processes has been pointed out, there is little information about the follicular localization of their receptors. We investigated, with special reference to FDCs, the localization of cytokine receptors as well as cytokines themselves in human tonsils by several means, including immunochemistry, immunoelectron microscopy, reverse transcriptase polymerase chain reaction, and in situ hybridization. FDCs in the follicular apical light zone expressed transforming growth factor-beta receptor II (TGF-betaR II), granulocyte-macrophage colony-stimulating factor receptor alpha (GM-CSFRalpha; CDw116), tumor necrosis factor receptor I (TNFR I; CD120a), interleukin-1 receptor II (IL-1R II; CDw121b), IL-2 receptor beta (IL-2Rbeta; CD122), IL-4 receptor (IL-4R; CDw124), and IL-6 receptor (IL-6R; CD126), among the 10 receptors examined. Those in the basal light zone expressed strongly TNFR I and weakly GM-CSFR alpha, IL-1R II, IL-2Rbeta, IL-4R, and IL-6R, and often those in the outer and mantle zones expressed GM-CSFR alpha, IL-4R, and IL-6R. FDCs in the apical light zone expressed only TGF-beta among the 7 cytokines examined. On the other hand, follicular lymphocytes mainly in the light zone expressed 9 kinds of receptors, with the exception being TGF-betaR II; expression was rather frequent for TNF-alpha, IL-1alpha, and IL-2 and less frequent for TGF-beta, GM-CSF, IL-4, and IL-6. These data indicate that only FDCs mainly in the light zone express many cytokine receptors, although FDCs may produce the cytokine, TGF-beta. Cytokines may act not only on some follicular lymphocytes but also on most FDCs in the light zone expressing cytokine receptors.

Animals↗
PubMed1997

Protease-resistant form of insulin-like growth factor-binding protein 5 is an inhibitor of insulin-like growth factor-I actions on porcine smooth muscle cells in culture.

IGFs are pleiotrophic mitogens for porcine smooth muscle cells (pSMC) in culture. The effects of IGFs on cells are modulated by various insulin-like growth factor-binding proteins (IGFBP). IGFBP-5 is synthesized by pSMC and binds to the extracellular matrix. However, IGFBP-5 is also secreted into conditioned medium of cultured cells and is cleaved into fragments by a concomitantly produced protease. These fragments have reduced affinity for the IGFs and cleavage makes it difficult to assess the role of intact IGFBP-5. To study the consequence of accumulation of intact IGFBP-5 in medium, we determined the cleavage site in IGFBP-5 and prepared a protease resistant mutant. Amino acid sequencing of purified IGFBP-5 fragments suggested Arg138-Arg139 as the primary cleavage site. Arg138-Arg139-->Asn138-Asn139 mutations were introduced to create protease-resistant IGFBP-5, which has the same affinity for IGF-I as the native protein. This mutant IGFBP-5 remained intact even after 24 h of incubation and it inhibited several IGF-I actions when added to pSMC culture medium. The mutant IGFBP-5 (500 ng/ml) decreased IGF-I stimulated cellular DNA synthesis by 84%, protein synthesis by 77%, and it inhibited IGF-I stimulated migration of pSMC by 77%. It also inhibited IGF-I stimulation of IRS-1 phosphorylation. In contrast, the same amount of native IGFBP-5 did not inhibit IGF-I actions. The significance of inhibitory effects of the protease resistant IGFBP-5 was further demonstrated in pSMC transfected with mutant or native IGFBP-5 cDNAs. The mutant IGFBP-5 accumulated in culture medium of transfected cells, while native IGFBP-5 was degraded into fragments, PSMC overexpressing the mutant IGFBP-5 also responded poorly to IGF-I compared with mock transfected cells. IGF-I (5 ng/ml) increased [35S]methionine incorporation into control cells by 36% above the basal level, but it did not significantly change (4%) in pSMC cultures that were producing the mutant IGFBP-5. In conclusion, the accumulation of protease-resistant IGFBP-5 in the medium was inhibitory to IGF-I actions on pSMC. This suggests that proteolysis can prevent IGFBP-5 from acting as an inhibitor of IGF-I-stimulated effects and that it serves as an important mechanism for regulating cellular responsiveness to IGF-I.

Amino Acid Sequence↗
PubMed1997

The characteristic gene expressions of MAPK phosphatases 1 and 2 in hepatocarcinogenesis, rat ascites hepatoma cells, and regenerating rat liver.

mRNA levels of mitogen-activated protein kinase phosphatases, MKP-1 and MKP-2, were determined during chemical hepatocarcinogenesis and during regeneration of rat liver. In chemical hepatocarcinogenesis, the mRNA levels of MKP-1 were increased in primary hepatomas but decreased in rat ascites hepatomas as compared with normal liver. MKP-2 was undetectable in normal liver but strongly expressed in hepatomas. The MKP-2 mRNA level was increased with expression of malignant phenotypes in hepatomas. In regenerating liver, the mRNA level of MKP-1 increased immediately but transiently after partial hepatectomy, and peaked again on day 10, the time when hepatocytes cease proliferation. The elevated expression of MKP-1 on day 10 suggests some roles of MKP-1 as a negative regulator in hepatocyte proliferation.

Animals↗
PubMed1997

Expression of rat cGMP-binding cGMP-specific phosphodiesterase mRNA in Purkinje cell layers during postnatal neuronal development.

The cDNA encoding rat cGMP-binding, cGMP-specific phosphodiesterase (cGB-PDE) was isolated from a rat lung cDNA library. Although the deduced amino acid sequence showed 93.4% similarity with that of bovine cGB-PDE, the N-terminal portion of rat cGB-PDE was extremely different from that of bovine. Northern blot analysis indicated that cGB-PDE transcripts in rats were expressed not only in aorta and lung, but also in several other tissues including cerebellum. In situ hybridization analysis demonstrated that cerebellar expression of cGB-PDE was confined to Purkinje cell layers in adult rats. To clarify the role of cGB-PDE in the cerebellum, we investigated expression of cGB-PDE mRNA in rats of various ages. cGB-PDE mRNA was not observed in the cerebellum of newborn rats, but levels of a cGB-PDE mRNA were markedly increased between 4 days and 28 days of age and reached a maximum in eight-week-old rats. In this study, we suggest that cGB-PDE plays important roles not only in regulating the relaxation of vascular vessels, but also in establishing neuronal networks in the cerebellum at an early postnatal stage. In addition the NO/cGMP/cGB-PDE pathway appears to be essential for the induction of long-term depression.

3',5'-Cyclic-GMP Phosphodiesterases↗