Biomedical subjects

M Sakurai

Publications and source records attributed to M Sakurai.

At least 163 records · Page 9Linked to original sources

PubMed1998

Identification and characterization of novel clathrin adaptor-related proteins.

We have identified a human approximately 87-kDa protein, designated as gamma2-adaptin, that is similar to gamma-adaptin (called gamma1-adaptin in this paper), a large chain of the AP-1 clathrin-associated adaptor complex, not only in the primary structure (60% amino acid identity) but also in the domain organization. Northern blot analysis has shown that its mRNA is expressed in a variety of tissues. Analysis using a yeast two-hybrid system has revealed that, similarly to gamma1-adaptin, gamma2-adaptin is capable of interacting not only with the sigma1 chain (called as sigma1A in this paper), the small chain of the AP-1 complex, but also with a novel sigma1-like protein, designated as sigma1B, which shows an 87% amino acid identity to sigma1A; and that, unlike gamma1-adaptin, it is unable to interact with beta1-adaptin, another large chain of the AP-1 complex. Immunofluorescence microscopy analysis has revealed that gamma2-adaptin is localized to paranuclear vesicular structures that are not superimposed on structures containing gamma1-adaptin. Furthermore, unlike gamma1-adaptin, gamma2-adaptin is recruited onto membranes in the presence of a fungal antibiotic, brefeldin A. These data suggest that gamma2-adaptin constitute a novel adaptor-related complex that participates in a transport step different from that of AP-1.

Adaptor Protein Complex 1↗

PubMed1998

The optical activity of lysozyme crystals.

The components of the gyration tensor of the enzyme lysozyme were measured by using the HAUP method: g11 = -0.90 x 10(-5) and g33 = 1.05 x 10(-5) at 303.4 K and a wavelength of 4880 A. The optical rotatory powers along the a and c axes in the same conditions were calculated: rho a = -21.3 and rho c = -24.8 degrees cm-1. The optically active property of lysozyme is strange in that, although it contains a considerable quantity of alpha-helices (about 30%), the rotatory powers are unexpectedly small in magnitude, one order of magnitude less than those of quartz and with very large anisotropy. A conceptual consideration of this phenomenon is given. In order to assess the difference between the structures in both crystalline and solution states, the chirality index r was calculated to be 0.16. This value indicates that the structural change of lysozyme from the solution into the crystalline state is expressed by an increase of 19% in optical activity. From the NMR results [Smith et al. (1993), J. Mol. Biol. 229, 930-944], it is anticipated that the r value reflects the increased constraint in atomic motion in the side chains of exposed amino acid residues in the crystalline state.

Animals↗

PubMed1998

Inductions of hepatocyte growth factor and its activator in rat brain with permanent middle cerebral artery occlusion.

Hepatocyte growth factor (HGF) is a potent pleiotrophic peptide which has a trophic role for neuronal cells. As it exerts its effect only after a conversion to its heterodimeric active form, the activation step, which is catalyzed by an enzyme serine protease named HGF activator (HGFA), is of great importance. HGF activated by HGFA may act as a protecting agent in injured brain. In the present study, we investigated expression of immunoreactive HGF and HGFA in rat brain after permanent middle cerebral artery (MCA) occlusion. By immunohistochemical analysis, HGF and HGFA were normally expressed only in ependymal cells and choroid plexus. At 1 h after MCA occlusion, neurons in the ischemic penumbra region of the cerebral cortex slightly expressed immunoreactive HGFA. HGF was not induced at that time. At 3 h of ischemia, however, immunoreactive HGF as well as HGFA became detectable in neurons of the ischemic cerebral cortex and caudate. Immunoreactivity for HGF continued to increase until 24 h, while that for HGFA remained almost constant from 3 to 24 h. No glial or vascular endothelial cells expressed HGF nor HGFA. By Western blot analysis for HGF, a single band of molecular weight (MW) 34 kDa became apparent at 24 h, corresponding to the light chain of the active form HGF. The present study suggests that HGF and HGFA were induced in neurons under permanent ischemia with slightly different temporal profiles. Through activation by HGFA, the active form of HGF could serve as a neurotrophic factor in ischemic brain.

Animals↗

PubMed1998

Changes in tumor marker levels as a predictor of chemotherapeutic effect in patients with gastric carcinoma.

BACKGROUND: Evaluating chemotherapeutic effect in patients with gastric carcinoma sometimes is difficult. The authors investigated whether changes in the serum levels of three tumor markers can be used to predict the clinical outcome after chemotherapy. METHODS: Thirty patients with advanced and recurrent gastric carcinoma were treated with continuous 5-fluorouracil and low dose cisplatin for 4 weeks. Thirteen patients were treated neoadjuvantly prior to gastrectomy. The serum levels of carcinoembryonic antigen, carbohydrate antigen 19-9, and sialyl-Tn antigen were measured prior to and after chemotherapy. Responders were defined as those in whom abnormal serum levels of all three markers decreased to at least 50% of the pretreatment values and remained stable for at least 1 month. RESULTS: The tumor markers could be evaluated in 27 of 30 patients (90%). The median duration of survival for the 15 responders and 12 nonresponders was 17 months and 6 months, respectively. There was a significant difference in the median duration of survival between the responders and nonresponders using the log rank test (P=0.0005). In the patients who received neoadjuvant therapy, the eight responders had a significantly longer survival period than did the three nonresponders (P=0.018). Seven of the eight responders showed evidence of tumor destruction histologically whereas none of the three nonresponders did. CONCLUSIONS: Changes in the serum levels of these tumor markers after chemotherapy may be an excellent prognostic indicator for patients with gastric carcinoma.

Adult↗

PubMed1998

Delayed selective motor neuron death and fas antigen induction after spinal cord ischemia in rabbits.

The mechanism of spinal cord injury has been thought to be related with tissue ischemia, and spinal motor neuron cells are suggested to be vulnerable to ischemia. To evaluate the mechanism of such vulnerability of motor neurons, we attempted to make a reproducible model for spinal cord ischemia. Using this model, cell damage was histologically analyzed. Detection of ladders of oligonucleosomal DNA fragment was investigated with gel electrophoresis up to 7 days of the reperfusion. Time course expression of Fas antigen, identified as a apoptosis-regulating molecules, was also assessed in rabbit spinal cord following transient ischemia. Spinal cord sections from animals sacrificed at 8 h, 1 day, 2 days, and 7 days following 15-min ischemia were immunohistochemically evaluated using monoclonal antibodies for Fas antigen. Following 15-min ischemia, the majority of motor neuron showed selective cell death at 7 days of reperfusion. Typical ladders of oligonucleosomal DNA fragments were detected at 2 days of reperfusion. Immunoreactivity of Fas antigen were induced at 8 h to 1 day of reperfusion selectively in motor neuron cells. The expression of Fas antigen may be related to the activation of apoptosis signal in motor neuron cells after spinal cord ischemia in rabbits.

Animals↗

PubMed1998

Down-regulation of Fas-associated phosphatase-1 (FAP-1) in interleukin-2-activated T cells.

Peripheral T cells are resistant to Fas receptor (FasR/CD95)-mediated apoptosis. After prolonged treatment with interleukin-2 (IL-2), these T cells develop a Fas-sensitive phenotype. To clarify the molecular mechanism of apoptosis susceptibility, mRNA expression of FasR-associated proteins [Fas-associating protein with death domain (FADD), receptor-interacting protein (RIP), and Fas-associated phosphatase-1 (FAP-1)] has been investigated in IL-2 activated T cells. Competitive reverse transcriptase-polymerase chain reaction analysis revealed that FADD and RIP mRNA were equally expressed in freshly isolated resting T cells and IL-2-activated T cells. In contrast, FAP-1 mRNA was produced more abundantly by Fas-resistant resting T cells than by Fas-sensitive activated T cells. These findings suggested that sensitivity to FasR-mediated apoptosis in T cells could be correlated with down-regulation of FAP-1 expression. Additionally, CD45RO+ memory T cells expressed a larger amount of FAP-1 mRNA than did CD45RA+ naive T cells.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Phosphorylation of vimentin by Rho-associated kinase at a unique amino-terminal site that is specifically phosphorylated during cytokinesis.

We found that vimentin, the most widely expressed intermediate filament protein, served as an excellent substrate for Rho-associated kinase (Rho-kinase) and that vimentin phosphorylated by Rho-kinase lost its ability to form filaments in vitro. Two amino-terminal sites on vimentin, Ser38 and Ser71, were identified as the major phosphorylation sites for Rho-kinase, and Ser71 was the most favored and unique phosphorylation site for Rho-kinase in vitro. To analyze the vimentin phosphorylation by Rho-kinase in vivo, we prepared an antibody GK71 that specifically recognizes the phosphorylation of vimentin-Ser71. Ectopic expression of constitutively active Rho-kinase in COS-7 cells induced phosphorylation of vimentin at Ser71, followed by the reorganization of vimentin filament networks. During the cell cycle, the phosphorylation of vimentin-Ser71 occurred only at the cleavage furrow in late mitotic cells but not in interphase or early mitotic cells. This cleavage furrow-specific phosphorylation of vimentin-Ser71 was observed in the various types of cells we examined. All these accumulating observations increase the possibility that Rho-kinase may have a definite role in governing regulatory processes in assembly-disassembly and turnover of vimentin filaments at the cleavage furrow during cytokinesis.

Amino Acid Sequence↗

PubMed1998

Crystallization and preliminary X-ray studies on the hyperstable 3-isopropylmalate dehydrogenase from the thermoacidophilic archaeon Sulfolobus sp. strain 7.

3-Isopropylmalate dehydrogenase from the thermoacidophilic archaeon, Sulfolobus sp. strain 7, has been crystallized by the vapor-diffusion method. The crystals were grown from a solution containing ammonium sulfate, 2-methyl-2,4-pentanediol and magnesium chloride. The crystallization requires 2-methyl-2,4-pentanediol to avoid twinning of the crystals. The crystal belongs to the orthorhombic system with the space group P2221 and unit-cell dimensions a = 67.9, b = 93.3 and c = 134.1 A.

3-Isopropylmalate Dehydrogenase↗

PubMed1998

Upgraded IR beamline at UVSOR.

BL6A1, a far-infrared (FIR) beamline at UVSOR, originally built in 1986, has been recently upgraded. The upgrade included the introduction of a second FT-IR spectrometer, making it possible to cover the entire FIR-IR range (3-10000 cm(-1)) in one sequence of measurements, without having to open the sample chamber; the beamline has become a more convenient and powerful experimental station than before. The upgrade is also expected to enable such experiments as IR studies of molecules adsorbed on solid surfaces, and time-resolved IR spectroscopies. This paper describes the characteristics of the upgraded BL6A1.

Journal Article↗

PubMed1998

CD4+ and CD8+ cell cytokine profiles in neonates, older children, and adults: increasing T helper type 1 and T cytotoxic type 1 cell populations with age.

The growing body of evidence suggestive of T helper types 1 and 2 (Th1/Th2) including their counterparts T cytotoxic types 1 and 2 (Tc1/Tc2) cell responses during various human disease states necessitates determination of normal T cell subsets' cytokine profiles. We show here, using intracellular cytokine staining and flow cytometry, that in healthy subjects interferon (IFN)-gamma producing CD4+ (Th1) and CD8+ (Tc1) cell populations progressively increase with age with strong correlation to CD45RO surface antigen expression. Meanwhile populations of cells capable of producing IL-4 (Th2 and Tc2) are comparably minimal across all age groups. Collectively, these results may reflect the maturation and expansion of Th1 and Tc1 cell populations from the neonatal period to adulthood, most probably dependent on antigen exposure.

Adolescent↗

PubMed1998

Flow cytometric analysis of peripheral blood and bone marrow for tumor cells in patients with neuroblastoma.

BACKGROUND: Several sensitive surveillance tests reportedly have been used to detect occult neuroblastoma (NB) cells in peripheral blood (PB) and bone marrow (BM). They may be useful in monitoring minimal residual tumor cells. The authors report the feasibility and clinical usefulness of a sensitive flow cytometric assay that has been newly developed and evaluated to detect NB cells. METHODS: Nine NB patients and 15 healthy donors were included in the current study. Primary tumor tissues, BM, and PB were examined for the detection of NB cells using a triple-color flow cytometric assay. Tumor cells in PB and BM, isolated by fluorescence-activated cell sorting, were used for morphologic studies and differential polymerase chain reaction analysis of N-myc gene amplification. RESULTS: Neuroblastoma cells consistently showed CD9+/CD56+/CD45- phenotype. Flow cytometric analysis could detect NB cells at a level of 1 per 10(4-5) cells. The CD9+/CD56+/CD45- cell population was absent in normal PB and BM. This assay identified occult NB cells, which were not detected by conventional cytology, in PB and BM obtained from six patients (one of two with Stage II and all five with advanced disease) at diagnosis. Residual NB cells also were detected in PB and BM during therapy. Neuroblast-like morphology and N-myc gene amplification of sorted cells confirmed that CD9+/CD56+/CD45- cells were truly NB cells. CONCLUSIONS: A triple-color flow cytometric assay was a sensitive and specific method to detect occult NB cells in PB and BM. This assay could be an additional component of surveillance testing for NB patients.

Antigens, CD↗

PubMed1998

Thymic B-cell non-Hodgkin's lymphoma in a child.

A 13-year-old male developed thymic non-Hodgkin's lymphoma. Microscopically, the tumor was composed of large cells, resembling centroblasts. Immunohistochemically, the tumor demonstrated leukocyte common antigen+, L26 (B-cell)+, UCHL1 (T-cell)-, suggesting the B-cell phenotype. In contrast to the terminally differentiated phenotype (CD10-, surface immunoglobulin-) observed in adult cases, flow cytometric analysis showed that they were relatively immature: CD10+, CD19+, HLA-DR-, IgM+/-, kappa+. He was successfully treated with intensive chemotherapy. Since childhood thymic lymphomas are exclusively small non-cleaved cell lymphoma with T-cell phenotype, this case represents a unique entity in children.

Adolescent↗

PubMed1998

Transfusion-associated graft-versus-host disease in immunocompetent patient: early diagnosis and therapy.

We report a case of transfusion-associated graft-versus-host disease in a previously healthy, 68-year-old Japanese man following an emergency surgery for an acute aortic dissection. We confirmed the chimerism of lymphocytes and the effect of drug therapy using DNA polymorphism analysis. This method is a sensitive, convenient, and rapid method that it is also useful for the evaluation of therapy. And the combination therapy with methylprednisolone, cyclosporine, and 15-deoxyspergualin may be effective in treating transfusion-associated GVHD.

Aged↗

PubMed1998

Thrombopoietin level is inversely related to blast count, not platelet number, in Down syndrome neonates with transient myeloproliferative disorder.

Transient myeloproliferative disorder (TMD) in neonates with Down syndrome is characterized by increased megakaryoblastic cells in the peripheral blood. Despite their spontaneous regression in weeks, prognosis is not always favorable because of fatal hepatic fibrosis. In this study, blood thrombopoietin (TPO) levels were measured by ELISA in six TMD patients and the expression of c-Mpl, a ligand for TPO, was examined on the blast cells from four patients by flow cytometer. At the onset, TPO level was undetectable in one patient and significantly lower in five patients than six neonatal controls (mean 0.52 fmol/ml, range 0.30-0.93 vs. 3.70, 1.38-8.33, P < 0.001), although platelet counts were similar (mean 321 x 10(9)/l, range 42-1,040 vs. 253 x 10(9)/l, 124-381). Two patients died of hepatic failure. TPO levels were measured in five patients after regression of the blast cells. With regression of blast cells, TPO levels were remarkably increased in four survived patients. In one patient with hepatic failure, TPO level was poorly elevated and relatively lower compared to the others. TPO levels were inversely correlated with blast numbers (r = -0.85, P < 0.001), but not with platelet counts (r = 0.426). Blast cells from four patients were all positive for c-Mpl. Our findings suggest that megakaryocyte mass is a major regulator of TPO levels and hepatic failure may affect the TPO level because liver is a major source of TPO production.

Cell Count↗

PubMed1998

CD4+ T-lymphocytopenia in long-term survivors following intensive chemotherapy in childhood cancers.

BACKGROUND: It is generally believed the effects of short intensive courses of therapy are rapidly reversible in childhood cancers, and immunologic function following years of maintenance treatment with chemotherapy usually returns to normal by 6 months or less when treatment is terminated. However, we previously demonstrated that dysregulation of immunoglobulins, especially IgD, was observed in long-term survivors following intensive chemotherapy in cancer patients. With regard to cellular immunity, investigators reported that antineoplastic chemotherapy significantly reduces the number of CD4+ T-lymphocytes, and production of newly developing CD4+ T-lymphocytes was inversely related to the patients' age. However, the incidence of CD4+ lymphocytopenia in long-term survivors of childhood cancers is not known. PROCEDURE: Here, we report the flow cytometric analysis of peripheral blood from long-term survivors who continue complete remission off chemotherapy for more than 5 years. RESULTS: Six out of 74 long-term survivors (8.1%), showed low CD4+ T-lymphocyte count (<300/mm3). Three of six patients showed continued CD4+ T-lymphocytopenia over a year. In spite of the persistent low levels of CD4+ T cells, these three patients were not susceptible to severe infections. COMMENT: Intriguingly, in patients with CD4+ T-lymphocytopenia there has been a tendency toward increased numbers of natural killer cells or gamma delta T cells that may be operating as a thymus-independent compensatory mechanism to defend the hosts.

Adolescent↗

PubMed1998

[Left ventricular rupture following mitral valve replacement with preservation of posterior leaflet].

Left ventricular rupture following mitral valve replacement (MVR) with preservation of the posterior leaflet is presented. A 63-year-old man underwent combined AVR, MVR with preservation of the posterior leaflet and TAP under cardiopulmonary bypass with moderate hypothermiat to 28 degrees C and tepid blood cardioplegia. Although a 31-mm valve would fit to the mitral position, a 27 TEKNA was chosen for MVR. Beyond the cardiopulmonary bypass, a left ventricular rupture was found. Cardiopulmonary bypass was re-stated and the aortic clamp was replaced. After removal of the mitral valve prosthesis, an internal tear was detected below the anterolateral commissural area (Type I). The tear was repaired with two 3-0 monofilament buttressed sutures incorporated with felt strips and covered with a bovine pericardial patch by several interrupted pledgeted mattress sutures. Gelatin-resorcin-formaldehyde/Glutaraldehyde glue (GRF) was used to reinforce the ruptured myocardium and to fix a bovine pericardial patch to the affected ventricular wall. Then the prosthesis was re-seated. Although the aortic clamp time was 319 mins., the patient was weaned from the cardiopulmonary bypass easily with the prophylactic use of IABP. The patient was discharged and returned to his previous job.

Aortic Valve↗

PubMed1998

[Open distal anastomosis or aortic balloon occlusion technique during complete aortic arch replacement].

The technique of open distal anastomosis or application of aortic balloon occlusion catheter designed to occlude the descending thoracic aorta have been used in 33 and 19 patients, respectively, to control bleeding during the procedure of distal anastomosis for complete aortic arch replacement with a prosthetic graft. These two techniques allowed us a simple approach to the lesion and the avoidance of clamp injury to the fragile aortic tissue. Open distal anastomosis was applied for 91% patients of operated aortic dissection and all emergent cases, it's duration ranged from 10 to 110 minutes with an average of 58 minutes under 18.2 degrees C of lowest esophageal temperature. On the other hand, aortic occlusion balloon was inserted for mainly true aortic aneurysm patients without an emergency, and helped to maintain the perfusion pressure on a lower part of body around 50 mmHg by the 1550 ml/min in an average of perfusion flow femoral artery under 21.2 degrees C of temperature. The difference of postoperative renal and liver function evaluated by serum enzyme levels of total bilirubin, GOT, GPT, LDH, creatinine and BUN did not reach to statistical significance between the patients using open distal anastomosis and balloon occlusion, however, the incidence of postoperative complication including either renal, liver dysfunction, abdominal problem or paraplegia was significantly higher in the patient group with open distal technique. Either open distal anastomosis or aortic balloon occlusion technique would be appropriately selected according to the patient's characteristics or the condition of aortic disease to be operated.

Aged↗

PubMed1998

Hepatocellular carcinoma with chondrosarcomatous variation: case report with immunohistochemical findings, and review of the literature.

Hepatocellular carcinoma with chondrosarcomatous variation is very rare. We report a case with the results of pathology examination, and review the literature. The patient, a 72-year-old may had a very large tumor in the liver revealed during follow-up for diabetes mellitus. The liver mass, which was 14 cm in diameter, was diagnosed as hepatocellular carcinoma by abdominal ultrasonography. Anterior segmentectomy and partial liver resection were performed. Histopathology examination revealed that the tumor consisted of two different components: the major one was hepatocellular carcinoma (HCC), which occupied most of the tumor; and a sarcomatous component, which occupied a smaller area, and included spindle-shaped cells with chondroscarcomatous variation. Intrahepatic metastases and tumor thrombi of HCC were also found in portal and hepatic veins. Investigations of the immunohistochemical localization of keratin (KRT), vimentin (VMT), and S-100 protein (S 100) were performed by the avidin-biotin complex method. Some of the spindle cells were immunohistochemically positive for both KRT and VMT, and the chondrosarcomatous cells were positive for S 100. These results strongly suggested that the sarcomatous lesion resulted from a sarcomatous change of HCC.

Aged↗