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S Sekiguchi

Publications and source records attributed to S Sekiguchi.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Blood flow velocity in the ophthalmic artery measured by Doppler ultrasonography during cardiopulmonary bypass--usefulness for cerebral perfusion monitor].

Brain blood flow is supplied from the internal carotid artery, and the ophthalmic artery is the first branch of the internal carotid artery. We studied how blood flow velocity in the ophthalmic artery (OAV) changes during cardiopulmonary bypass (CPB) and investigated whether it can be used to monitor brain blood flow during CPB. In 13 open heart surgeries in adults, OAV and blood flow velocity in the common carotid artery (CAV) were measured with Doppler ultrasonography, and blood flow volume in the brachiocephalic artery (BA flow) was measured simultaneously with an electromagnetic flow meter. Maximal blood flow velocity in the ophthalmic artery (OAVmax) and the common carotid artery (CAVmax) were 0.27 +/- 0.13 m/sec and 0.64 +/- 0.40 m/sec, BA flow was 486 +/- 226 ml/min before CPB. When CPB pump flow was varied (2.4, 2.2, 2.0, 2.2, 2.4 l/min/m2), the parameters during and after CPB changed as follows (as percentage of pre-CPB levels): OAVmax, 58.1%, 50.9%, 37.6%, 49.4%, 64.7%, 108.4%; CAVmax, 67.0%, 58.0%, 48.2%, 113.6%, 105.5%, 134.3%; and BAflow, 87.3%, 39.8%, 53.9%, 50.5%, 95.0%, 159.8%. Our results indicate that OAVmax more accurately reflects changes in pump flow than does CAVmax and BA flow. Because vessel resistance in the ophthalmic artery was small during CPB, OAVmax was thought to be determined mainly by CPB pump flow. OAVmax was useful for monitoring brain blood flow during CPB.

Adult↗
PubMed1998

[Effects of myocardial protection with ryanodine, measured with the intracellular calcium fluprescent indicator Fura-2].

The effects of Ryanodine, an inhibitor of salcoplasmic reticulum function, was investigated in isolated hearts of the Wistar rat strain. The cytosolic calcium was measured with the intracellular Ca2+ fluorescent indicator Fura-2. After 3 minutes perfusion of various cardioplegic solution which were added potassium (the concentration; 20 mmol/L) and four Ryanodine groups (1, 4, 10, and 20 nmol/L), these were obtained cardiac arrest. The arrested hearts were kept at 37 degrees C (normothermia) measuring hemodynamic studies. Hemodynamic parameters were heart rate, LVDP, LV dp/dt, coronary flow, and the intracellular calcium fluorescents which were calculated intracellular Ca2+. The significant difference was not noted in LVDP, but comparable improvement was achieved with Ryanodine groups (p < 0.05; 20 nM vs 0 nM). Other cardiac functions were likely same as above. The cytosolic calcium concentration of Ryanodine groups was depressed during cardiac arrest, it was 97.4 +/- 17.2% at the end of cardiac arrest, and it was slowly increased to 161.9 +/- 46.9% after 40 minutes reperfusion. On the other hand, that of the control group was higher than Ryanodine groups at every measuring points about two times. There was significant difference between both groups (p < 0.01). Concequently these phenomena caused that Ca2+ handling in the salcoplasmic reticulum were supressed by Ryanodine and the contractile function was recovered for that reason.

Animals↗
PubMed1998

Culture system for extensive production of CD19+IgM+ cells by human cord blood CD34+ progenitors.

We established a co-culture system with a monolayer of the murine bone marrow (BM) stroma cell line, MS-5, in which human cord blood CD34+ cells differentiated to CD19+ cells. The addition of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) highly enhanced the production of CD19+ cells. The expansion of the cell numbers was over 10(3)-fold. Furthermore, a significant proportion (<45%) of the cells expressed surface IgM (sIgM) after 5 weeks of co-culture. CD34+CD19- cells also showed a similar development of CD19+ cells and CD19+sigM+ cells. Filter separation of MS-5 cells and CD34+ cells did not inhibit the growth of CD19+ cells. However, when further purified CD34+CD19-CD13- CD33- cells were cultured in the presence of MS-5 cells with or without a separation filter, CD19+ cells did not appear in the non-contact setting. This result suggested that the highly purified CD34+CD19-CD13-CD33- progenitors require the cell-cell contact for the development of CD19+ cells, whereas other CD34+ fractions contain progenitors that do not require the contact. This co-culture system should be useful for the study of early human B-lymphopoiesis.

Animals↗
PubMed1998

IL-6 and SCF exert different effects on megakaryocyte maturation.

Megakaryocytic maturation has two aspects, nuclear maturation and cytoplasmic maturation, both of which are affected by several thrombopoietic cytokines. We cultured murine bone marrow cells separated by BSA velocity sedimentation which contained more immature megakaryocytes with lower ploidy in order to study the effects of rhIL-6 and rmSCF on the two aspects of megakaryocyte maturation. During culture with rhIL-6 or rmSCF for 4 d, the megakaryocytes underwent endomitosis, resulting in DNA polyploidization. These two cytokines had different effects on cytoplasmic maturation. Flow cytometry showed that the megakaryocytes cultured with rhIL-6 became larger and had a more complex intracellular structure than those cultured with rmSCF. Morphological studies showed that the megakaryocytes cultured with rhIL-6 were larger and more granular, whereas those cultured with rmSCF were smaller and more basophilic. rhIL-6 promoted cytoplasmic process formation by the megakaryocytes, but rmSCF did not. Analysis of transcripts of PF-4 and GPIIb by RT-PCR suggested that rmSCF kept more megakaryocytes at the protein synthesis stage than did rhIL-6. Based on our findings, these cytokines exert different effects on megakaryocytic cytoplasmic maturational events.

Animals↗
PubMed1998

Virus inactivation in superoxide dismutase preparations by ultraviolet light irradiation.

Viral inactivation in superoxide dismutase (SOD) derived from human red cells was carried out by ultraviolet light C (UVC) irradiation. With 400 J/m2 UVC irradiation, the titer of canine parvovirus (CPV, a nonenveloped virus), M13 bacteriophage (M13, a nonenveloped phage) and vesicular stomatitis virus (VSV, an enveloped virus), which were spiked into SOD solution, were reduced by > 4.6 log10 (detection limit), 7.0 log10 and 6.2 log10, respectively. The SOD activity was maintained and the band pattern of SOD on an electrophoresis gel was not changed even by 1000 J/m2 UVC irradiation. These results indicate that UVC irradiation is a promising method for the inactivation of both enveloped and nonenveloped viruses in SOD preparations while maintaining its activity.

Animals↗
PubMed1998

Influence of 2-bromopropane on reproductive system--2-bromopropane inhibits forced ovulation in mice.

The influence of 2-bromopropane, an alternative to freon, on ovulation was examined using superovulation induced by pregnant mare's serum gonadotropin and human chorionic gonadotropin (PMSG-hCG) treatment. Three groups of mice were injected intraperitoneally 8 times with 2-bromopropane (2-BP) at 500, 1,000 or 2,000 mg/kg and were induced to ovulate by PMSG-hCG treatment. Injection of 2-BP caused the number of ovulated ova in the 1,000 mg/kg and 2,000 mg/kg groups to decrease remarkably. Uterus weight was also decreased in the 2,000 mg/kg group on the terminal day of the experiment. This result was consistent with cases of human intoxication in which reproductive toxicity was observed.

Animals↗
PubMed1998

Effects of liposome-encapsulated hemoglobin on phorbol ester-induced superoxide production and expression of costimulatory molecules by monocytes in vitro.

The effects of Neo Red Cell (NRC), a liposome-encapsulated hemoglobin (LEH), on the phorbol ester-induced superoxide production and the expression of costimulatory molecules by human peripheral monocytes were investigated. The treatment of human mononuclear cells with NRC caused the potentiation of superoxide production in response to PMA. The longer incubation (20 h) resulted in a decrease in the PMA-induced superoxide production, which was in parallel to a decrease in the viability of the monocytes. A flow cytometric analysis showed that a slight expression of CD80 (B7-1) on monocytes was induced by NRC treatment, whereas the constitutive expressions of CD86 (B7-2) and CD54 (ICAM-1) were unchanged. The activation of monocytes with interferon-gamma (IFN-gamma) induced the expressions of CD80, CD86, and CD54 under all conditions tested, but NRC treatment tended to decrease the IFN-gamma-induced expression of CD54 on monocytes. These results suggest that the administration of LEH may modify the functions of human monocytes.

Antigens, CD↗
PubMed1998

Platelet-like particle production from cultured human megakaryocytic cell line.

The human megakaryocytic cell line CMK was positive for the expression of platelet glycoprotein(GP) IIb/IIIa but few cells were positive for GPIb. To establish a GPIb-positive CMK subclone, GPIb-positive CMK cells were purified, micromanipulated and cloned, but resulting sublines were all negative for GPIb expression. The combined presence of interleukin-3 (IL-3) and the anti-virus agent ribavirin strongly induced expression of GPIb on the cells. However, the megakaryocyte growth and development factor (MGDF)/thrombopoietin (TPO) failed to enhance GPIb expression. CMK themselves and particles are negative for GPIb expression. To utilize these particles as platelet substitutes, further appropriate culture systems are necessary.

Blood Platelets↗
PubMed1998

Inflammatory cytokine production in whole blood modified by liposome-encapsulated hemoglobin.

The effect of Neo Red Cells (NRC), liposome-encapsulated hemoglobin, on production of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) were studied in whole blood preparations ex vivo. Venous blood was collected with heparin and incubated in a CO2 incubator. Treatment of blood samples with NRC reduced the constitutive levels of TNF-alpha and IL-6. Lipopolysaccharide (LPS) treatment for 24 h increased production of TNF-alpha and IL-6 in a dose-dependent manner. Pretreatment with NRC (5%) for 24 h markedly potentiated the LPS-induced TNF-alpha production and, that of IL-6 to a lesser extent. Northern blotting analysis of total RNA in whole blood showed that pretreatment with NRC caused a marked increase in TNF-alpha mRNA expression in response to LPS. It is concluded that NRC potentiates LPS-induced TNF-alpha and IL-6 production in whole blood ex vivo, and that the potentiating effect of NRC on LPS-induced TNF-alpha production can be attributed, at least in part, to an increase in its mRNA expression.

Adult↗
PubMed1998

Variable expression on lung cancer cell lines of HLA-A2-binding MAGE-3 peptide recognized by cytotoxic T lymphocytes.

Cytotoxic T lymphocytes (CTL) specific for HLA-A2-binding MAGE-3 peptide (FLWGPRALV) were generated by repetitive stimulation of PBMC with the peptide in the presence of EBV-transformed B blasts and IL-2. Using these CTL, we investigated the expression of the HLA-A2-binding MAGE-3 peptide on lung cancer cell lines. Of 14 cell lines investigated, 1-87, PC-9, OU-LC-KI, 11-18 and LK87 were derived from HLA-A2 positive patients. But cytofluorometry analysis showed that 1-87, PC-9 and OU-LC-KI, but not 11-18 or LK87 expressed the HLA-A2 antigen. All five cell lines expressed MAGE-3 gene mRNA. Twelve of thirteen CTL lines from two HLA-A2 positive donors showed no cytotoxicity against any of the 14 lung cancer cell lines. CTL line TI-1 showed cytotoxicity against 1-87 but not against any of the other cell lines. Treatment of 1-87 with IFN-gamma greatly augmented the cytotoxicity of TI-1 and induced it in the other 12 CTL lines, confirming the expression of the peptide on 1-87. No cytotoxicity was induced by IFN-gamma treatment of PC-9 or OU-LC-KI. However, PC-9 and OU-LC-KI pulsed with the peptide were killed efficiently by all of the CTL lines, suggesting no expression of the peptide on those cells. A low level of cytotoxicity was induced on 11-18 but not LK87 by IFN-gamma treatment, although expression of the HLA-A2 antigen was not observed by cytofluorometry. These findings showed that expression of the HLA-A2-binding MAGE-3 peptide recognized by CTL was variable on lung cancer cell lines.

Amino Acid Sequence↗
PubMed1998

In vitro expansion of CD34+/CD41+ cells from human peripheral blood CD34+/CD41- cells: role of cytokines for in vitro proliferation and differentiation of megakaryocytic progenitors.

The aim of this study is to clarify the transitional change of the proliferation and differentiation of human peripheral blood CD34+ cells to megakaryocytic lineage, focusing on its clinical application. We developed a rapid system to purify human peripheral blood CD34+ cells from healthy volunteers, which produced CD34+ cells with a 90% purity. The purified CD34+ cells predominantly consisted of CD41- cells, and the rate of coexpression of CD41 was 0.6% +/- 0.5%. When the purified cells were cultured in liquid phase for 10 days in the presence of recombinant human stem cell factor (rSCF: a ligand for c-kit), interleukin-3 (rIL-3), and thrombopoietin (rTPO: a ligand for Mpl), the number of CD34+/CD41+ cells increased to 19% +/- 7% of total expanded cells on day 4 (4 days of liquid culture) and then gradually decreased to 2.2% +/- 0.6% on day 10. The absolute number of CD34+/CD41+ cells increased and reached a plateau on day 6, and 1.7 +/- 0.6 x 10(5) CD34+/CD41+ cells were produced by 1 x 10(5) CD34+/CD41- day 0 cells. The CD34-/CD41+ cells appeared on day 6, continuously increased in number until day 10, and constituted the main population of expanded cells on day 10, with a value of 38% +/- 18%. On day 10, 19.5 +/- 10.6 x 10(5) of CD34-/CD41+ cells were produced by 1 x 10(5) CD34+/CD41- day 0 cells. The deletion of rTPO from this cytokine combination decreased the number of CD34+/CD41+ and CD34-/CD41+ cells, after days 6 and 8, respectively. Day 0 cells required rIL-3 for promoting colonies containing megakaryocytes, whereas rTPO alone promoted almost no megakaryocytic colonies from day 0 cells. Thus, a combination of IL-3 and SCF expands CD34+/CD41+ cells from CD34+/CD41- cells, and TPO mainly acts to increase CD34-/CD41+ cells. This study suggests that if the expansion of CD34+/CD41+ is performed in vitro, the 6 days' culture of peripheral blood CD34+/CD41- cells with a combination of IL-3 and SCF with TPO provides the most rapid and stable products of CD34+/CD41+ cells for the rapid recovery of platelets in patients with peripheral blood stem cell transplantation.

Adult↗
PubMed1997

Analysis of the involvement of the von Willebrand factor-glycoprotein Ib interaction in platelet adhesion to a collagen-coated surface under flow conditions.

The requisite initial reaction for in vivo thrombus formation in flowing blood is platelet adhesion to the exposed surface of the extracellular matrix. The contribution of von Willebrand factor (vWF ) in plasma and glycoprotein (GP) Ib on the platelet membrane to platelet adhesion has been well-documented. We have recently developed a procedure (the "flow adhesion assay") for measuring platelet adhesion under flow conditions that allowed us to characterize platelet adhesion to a collagen-coated surface. Here, we apply our method to analyze platelet adhesion to a vWF-coated surface to determine how this might differ from adhesion to a collagen-coated surface. Platelet adhesion to the vWF-coated surface was monitored as the linear increase in the area occupied by adherent platelets. The fluorescence image showed that platelets adhering to the vWF surface were mainly single platelets, and if any were present, the platelet aggregates were small, this being the primary difference from the adhesion to a collagen surface, where adherent platelets were mostly in aggregates. The flow adhesion assay detected the movement of platelets on the vWF surface, suggesting the reversible binding of vWF with platelets. The velocity of the platelets increased at higher shear rates or at lower vWF densities on the surface. Treatment of the vWF-coated surface with the aggregating agent botrocetin before initiation of blood flow increased platelet adhesion while dramatically decreasing the velocity of platelet movement. The present observations on the adhesion of platelets to the vWF-pretreated collagen surface and measurements of the velocity of platelets moving on the collagen surface suggest that the first interaction on the collagen-coated surface is the binding of vWF molecules to the collagen surface. This small number of vWF molecules would serve to attract and slow platelets flowing near the surface. This would facilitate the actual adhesion to the collagen surface that is mainly generated by the interaction between platelet collagen receptors, including GP Ia/IIa and GP VI, with collagen.

Adsorption↗