Search PubMed⌕ Search

Biomedical subjects

H Mohri

Publications and source records attributed to H Mohri.

At least 73 records · Page 4Linked to original sources
PubMed1997

Monophosphoryl lipid A enhances both humoral and cell-mediated immune responses to DNA vaccination against human immunodeficiency virus type 1.

To enhance immunity induced by DNA vaccination against human immunodeficiency virus type 1 (HIV-1), we evaluated the efficacy of monophosphoryl lipid A (MPL), an adjuvant of bacterial origin. BALB/c mice were intramuscularly injected with immunogenic DNA, encoding the env and rev genes of the HIV-1(IIIB) strain, formulated with MPL dissolved in different vehicles (MPL in stable emulsion and MPL in aqueous formulation). The sera from mice immunized with the two preparations of MPL revealed 2(6) to 2(9) times higher HIV-1-specific immunoglobulin G (IgG) titers than the sera from mice immunized without MPL. In virus neutralization tests for HIV-1(IIIB), by p24 assay and antifusion assay of infected MOLT-4 cells, MPL tends to elicit antibody more protective than antibody elicited without adjuvant. MPL also elicited stronger delayed-type hypersensitivity and cytotoxic-T-lymphocyte activity against HIV-1(IIIB) compared to DNA alone. HIV-1-specific IgG subclass analysis showed that MPL tends to facilitate IgG2a production, suggesting enhancement of a predominant T-helper-type-1 response, and this enhancement may help to facilitate protective-antibody induction. Furthermore, a chloramphenicol acetyltransferase (CAT) assay was employed to determine whether MPL affected the gene expression process. Interestingly, both MPL preparations reduced CAT activity in the muscle injected with CAT expression vector but increased anti-CAT antibody production. These results indicate that MPL acts as an effective adjuvant for immunogenic DNA injection despite reduced expression of encoding protein in muscle. We conclude that MPL has a strong adjuvant effect on DNA vaccination against HIV-1.

AIDS Vaccines↗
PubMed1997

In vitro and ex vivo anti-human immunodeficiency virus (HIV) activities of a new water-soluble HIV protease inhibitor, R-87366, containing (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid.

In a series of compounds containing (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid (AHPBA), a transitionstate mimetic, R-87366:(2S,3S)-3-[N-(quinoxaline-2-carbonyl)-L-asparaginyl]amino- 2-hydroxy-4-phenylbutanoyl-L-proline tert-butylamide, was found to be a potent human immunodeficiency virus protease inhibitor (Ki value was 11 nM) and anti-HIV agent (IC90 value was 0.5 microM for HIV-1IIIB acutely infected cells) with moderate water-solubility (4.2 mg/ml at 25 degrees C). The compound was also active in chronically infected Molt-4/HIV-1IIIB cells, and inhibited the proteolytic processing of p55 into p17, suggesting that its anti-HIV activity was derived from HIV protease inhibition. The compound showed more potent activity (IC90 value was 0.03-0.25 microM) against clinical isolates of HIV in 5 out of 6 patients examined with varying clinical status in an ex vivo assay. One isolate, however, from the sixth patient, was less sensitive to R-87366 (IC90 value was 0.5 microM). In experiments with this strain, R-87366 showed comparatively low efficacy in acutely infected peripheral blood mononuclear cell (PBMC). This result suggests that the diversity of sensitivity shown in the ex vivo assay could be caused by the viral property itself. As a result of the determination of nucleic acid sequences in the clinical isolates, some amino acids were found to be substituted in the protease region, in contrast to the HIV-1 clade B consensus sequence, and some of them have been reported to contribute to the susceptibility of HIV protease inhibitors.

Amino Acid Sequence↗
PubMed1997

Torsades de pointes complicating pentamidine therapy of Pneumocystis carinii pneumonia in acute myelogenous leukemia.

Pentamidine isethionate induced torsades de pointes in a 33-year-old woman with acute myelogenous leukemia. This is the first report of Pentamidine-induced torsades de pointes in Japan for over ten years. On the 4th day of intravenous pentamidine for Pneumocystis carinii pneumonia, asymptomatic sinus bradycardia was noted with QT interval prolongation, and torsades de pointes were revealed on the 8th day. Although torsades de pointes was dissolved with discontinuation of the intravenous pentamidine and administration of magnesium sulfate, sinus bradycardia and prolonged QT interval persisted. Ventricular pacing resulted in no arrhythmia and normalization of the QT interval on the 10th day after discontinuation of pentamidine. Careful monitoring of the electrocardiogram should be carried out during intravenous pentamidine therapy.

Adult↗
PubMed1997

[Minimally differentiated hypoplastic leukemia in two elderly patients].

Patient 1; A 78-year-old woman was admitted to our hospital because of general malaise. Her peripheral blood count showed bicytopenia of 900/microliter with 2% blasts, 7.0 g/dl hemoglobin, and 199,000/microliter platelets. Examination of bone marrow revealed hypocellular marrow with peroxidase-negative blasts (89%). Surface marker analysis of blast cells revealed CD13 agents. Electron-microscopically, myeloperoxidase staining was positive. The diagnosis was hypoplastic leukemia in which blasts had a feature of minimally differentiated acute myeloid leukemia (AML-MO). Patient 2; A 78-year-old man was admitted to our emergency unit because of dizziness and dyspnea on exertion. Examination of peripheral blood showed pancytopenia but no blast cells. Examination of bone marrow showed a markedly hypocellular marrow with 38% blast cells. These blast cells were negative for myeloperoxidase and they had CD13 antigen on their surfaces. The diagnosis was minimally differentiated hypoplastic leukemia. At the time of this writing these two patients had been receiving only red cell transfusions for about six months, and the disease had not progressed.

Aged↗
PubMed1997

Autoantibody selectively inhibits binding of von Willebrand factor to glycoprotein ib. Recognition site is located in the A1 loop of von Willebrand factor.

A 20-year-old man with severe von Willebrand disease recently presented a progressive bleeding tendency, characterized recurrent subcutaneous hemorrhages and cerebral hemorrhage. Mixing and infusion studies suggested the presence of an inhibitor directed against vWF:RCo activity of von Willebrand factor (vWF) without significant inhibition of the FVIII:C. The inhibitor was identified as an antibody of IgG class. The inhibitor inhibited the interaction of vWF in the presence of ristocetin and that of asialo-vWF with GPIb while it partially blocked botrocetin-mediated interaction of vWF to GPIb. The inhibitor reacted with native vWF, the 39/34 kDa fragment (amino acids [aa] 480/ 481-718) and the recombinant vWF fragment (MalE-rvWF508-704), but not with Fragment III-T2 (heavy chains, aa 273-511; light chains, aa 674-728). A synthetic peptide (aa 514-542) did not inhibit vWF-inhibitor complex formation. We conclude that this is the first auto-antibody of class IgG from human origin that recognizes the sequence in the A1 loop of vWF, resulting in a virtual absence of functional vWF and a concomitant severe bleeding tendency although recognition site is different from the residues 514-542 which is crucial for vWF-GPIb interaction.

Adult↗
PubMed1997

Upregulation of interferon-alpha receptor expression in hydroxyurea-treated leukemia cell lines.

BACKGROUND: Interferon-alpha (IFN-alpha) shows its antitumor effect through binding to specific cell surface receptors. A DNA synthesis inhibitor, hydroxyurea (HU), has been successfully combined with IFN-alpha to improve the efficiency of IFN therapy for chronic myelogenous leukemia (CML). To understand the mechanism of this combination effect, expression of IFN-alpha receptors on the CML cell line, K562, was studied before and after treatment with HU. METHODS: Cells were treated with HU at a dose of 0, 0.1, 0.2, or 0.4 mmol/L for 48 hours. Binding assays were performed using 125I-labeled IFN-alpha at 4 degrees C. Cell cycle analysis was carried out using flow cytometer following staining cellular DNA with propidium iodide. Northern blot analysis was performed to evaluate the inducibility of interferon regulatory factor-1 (IRF-1) gene expression by IFN-alpha. RESULTS: Hydroxyurea-treated cells showed a dose- and time-dependent increase in binding of 125I-labeled IFN-alpha (maximal 2.5-fold). The increase of binding was caused by an increase in the number of binding sites with a constant receptor affinity. Similar results were obtained in the Burkitt's lymphoma cell line, Daudi. Cell cycle analyses suggested that upregulation of the IFN receptor may have occurred as a result of the alteration in the cell cycle distribution. Furthermore, IFN-alpha induction of the IFN-inducible gene IRF-1 mRNA in HU-treated K562 cells was 2-fold higher than that in untreated cells. CONCLUSIONS: Thus, HU may have an ability to enhance the response to IFN-alpha probably because of its ability to upregulate the IFN-alpha receptors, suggesting that this may be involved in the mechanism of effective combination therapy of IFN-alpha with HU.

Antineoplastic Agents↗
PubMed1997

[Successful treatment of subdural hematoma with operation in a patient with acute promyelocytic leukemia].

A 51 year-old male admitted with petechiae and headache. Acute promyelocytic leukemia (APL) with disseminated intravascular coagulation (DIC) was diagnosed. He received all-trans retinoic acid (ATRA) with enocitabine and daunomycin for induction chemotherapy, and supportive therapy for DIC. On 2nd day after admission, subacute subdural hematoma was confirmed with CT scan. He had anisocoria and disturbance of consciousness, and was treated with neurosurgical operation for his life saving on the 3rd day. Although DIC was continued at this time, the operation was done without problem. The recurrence of hematoma has not occurred after the operation. Furthermore, the findings of DIC disappeared by the day 6 following induction therapy. He achieved a complete remission including cytogenetic findings on 35th day after administration of ATRA and received 3 times of combination chemotherapy as consolidation therapy. It may be difficult to do neurosurgical treatment in the setting of DIC. However, we should consider whether the indications for surgery operation according to the condition of each patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

[Graft-versus-leukemia effect induced by abrupt discontinuation of cyclosporine A following allogeneic bone marrow transplantation].

Cyclosporine A (CyA) was abruptly discontinued in an attempt to induce graft-versus-leukemia (GVL) effect following allogeneic bone marrow transplantation (BMT). It appeared that GVL effect was co-expressed with graft-versus-host disease (GVHD) in 2 of 4 patients and especially minimal residual disease was eliminated during GVHD in a patient with Philadelphia-positive acute lymphocytic leukemia. Subpopulation of cytotoxic T and natural killer cells increased significantly in patients with discontinuation of CyA. This finding suggests that GVL effect was increased following discontinuation of CyA. These results may provide a therapeutic strategy after BMT in patients with high-risk group for relapse of leukemia.

Acute Disease↗
PubMed1996

Interferon-gamma induces Ice gene expression and enhances cellular susceptibility to apoptosis in the U937 leukemia cell line.

The roles of interferons (IFNs) in apoptosis are not fully understood. In this study we show that in the U937 monoblastic leukemia cell line, pretreatment with IFN-gamma enhanced sensitivity to apoptosis triggered by gamma-irradiation or antitumor agents (etoposide or adriamycin), as well as by anti-Fas antibody. In addition, IFN-gamma caused an increased expression of the interleukin-1 beta-converting enzyme (Ice) gene, following strong induction of the interferon regulatory factor-1 (IRF-1) gene, the product of which is a transcriptional activator of the Ice gene. An inhibitor of ICE/Ced-3 family proteases, Z-Asp-CH2-DCB, blocked apoptosis in control cells as well as in IFN-gamma-pretreated cells. These results suggest that enhanced susceptibility of IFN-gamma-pretreated cells to apoptosis is mediated through the induction of Ice by IRF-1. This pathway is not affected by interleukin-1 beta (IL-1 beta) since neutralizing antibody against IL-1 beta failed to suppress the IFN-gamma-mediated enhancement of cell death, and IL-1 beta itself did not mimic the effect of IFN-gamma.

Antibiotics, Antineoplastic↗
PubMed1996

Identification of a novel binding site to the integrin alphaIIbbeta3 located in the C-terminal heparin-binding domain of human plasma fibronectin.

Fibronectin has been shown to bind to integrin alphaIIbbeta3 in Arg-Gly-Asp (RGD)-dependent and -independent manners. A recent study has indicated that a 29-kDa dispase-digestive fragment from the C-terminal heparin-binding domain of human plasma fibronectin (lacking RGD sequence) inhibits binding of fibronectin to thrombin-stimulated platelets and ADP-induced aggregation (Tanabe, J. , Fujita, H., Iwamatsu, A., Mohri, H., and Ohkubo, T.(1993) J. Biol. Chem. 268, 27143-27147). We provide here the evidence that a peptide corresponding to residues from Ala1704 to Glu1718 (designated F1) from this fragment inhibited binding of 125I-labeled 29-kDa fragment of fibronectin to thrombin-stimulated platelets and ADP-induced aggregation. The F1 peptide bound directly to alphaIIbbeta3 integrin receptor. These results indicate that a novel binding site in the C-terminal heparin-binding region of fibronectin is localized within the residues from Ala1704 to Glu1718. Binding of 125I-labeled 29-kDa fragment of fibronectin to thrombin-stimulated platelets was not inhibited by RGDS peptide and the 12-residue peptide from the cell-binding domain of fibronectin, suggesting that binding site in the C-terminal heparin-binding domain may be different from those of RGDS and the 12-residue peptide. This additional alphaIIbbeta3-binding domain(s) in fibronectin may also play some role for prevention of thrombus formation by direct interaction with alphaIIbbeta3.

Adenosine Diphosphate↗
PubMed1996

The novel recognition site in the C-terminal heparin-binding domain of fibronectin by integrin alpha 4 beta 1 receptor on HL-60 cells.

The hematopoietic cell recognition sites of human fibronectin (FN) are the Arg-Gly-Asp-Ser (RGDS) sequence recognized by widely distributed integrin receptor alpha 5 beta 1 and the type III connecting segment (III CS) containing two cell-binding sites, designated CS1 and CS5, that are recognized by the alpha 4 beta 1 receptor. The C-terminal heparin-binding domain of FN (Hep II) has recently been demonstrated to support adhesion of alpha 4 beta 1-dependent melanoma cells [A. P. Mould and M. J. Humphries (1991) EMBO J. 10, 4089-4095]. Previously we demonstrated that this region of FN mediated binding of FN to HL-60 cells (acute promyelocytic leukemia cell line) by direct interaction independently of RGD and CS1 [H. Fujita et al., (1995) Exp. Cell Res. 217, 484-488]. In this study we have characterized a novel site in the Hep II region for binding to HL-60 cells. alpha 4 beta 1 and alpha 5 beta 1 were expressed on HL-60 cells, while alpha 2 beta 1 and alpha 3 beta 1 were not present, as shown by flow cytometry using monoclonal antibodies specific for the different integrins. Anti-alpha 4 beta 1 (P4C2) and anti-beta 1 (JB1a) antibodies inhibited binding of a 29-kDa dispase-digestive fragment of FN to HL-60 cells. This fragment contains the C-terminal heparin-binding domain of FN but lacks CS1 and CS5. Only the peptide representing the sequence from Val1866 to Arg1880, designated E1, inhibited the binding of the 29-kDa fragment to HL-60 cells. The active region of this peptide was a sequence of Thr-Asp-Ile-Asp-Ala-Pro-Ser (TAI-DAPS), which is homologous to Leu-Asp-Val-Pro-Ser (LDVPS) derived from the active site of CS1. Furthermore, labeled E1 peptide directly bound to HL-60 cells. The anti-alpha 4 beta 1 antibody (P4C2) inhibited this interaction. These results indicate that the site of binding to hematopoietic cells is present in the Hep II region of FN and the definition of the chemical structure of FN clarifies a fundamental mechanism of cell invasion of the extracellular matrix.

Amino Acid Sequence↗
PubMed1996

Induction of HIV-1 Nef-specific cytotoxic T lymphocytes by Nef-expressing DNA vaccine.

Recently, some individuals who have remained seronegative despite definite exposure to HIV-1 have been reported. Among these individuals, an unusually high frequency of HIV-1 Nef-specific cytotoxic T lymphocytes was observed. Direct injection of plasmid DNA encoding foreign antigen can elicit both cell-mediated immunity and antibody responses (DNA vaccine). We constructed an HIV-1 Nef-expressing plasmid, and we induced HIV-1 Nef-specific cytotoxic T lymphocytes. This is the first report of inducing HIV-1 Nef-specific cytotoxic T lymphocytes by DNA vaccine.

Amino Acid Sequence↗
PubMed1996

Affinity of Fibrinogen Binding to Platelet Membrane Glycoprotein IIb/IIIa Increases with RGDS and gamma Chain Fibrinogen Peptide Hybrid.

Arg-Gly-Asp (RGD)-containing peptides and the peptide unique to fibrinogen in the C-terminal domain of the gamma chain are important for fibrinogen binding to platelet membrane glycoprotein (GP) II b/III a. We synthesized a unique hybrid peptide of YRGDSPLGGAKQAGDV encompassing the RGD sequence (RGDS) with the gamma chain peptide (LGGAKQAGDV). Maximum binding to thrombin-stimulated platelets was achieved within 40 minutes with the YRGDS peptide and within 20 minutes with the hybrid peptide and native fibrinogen. The platelet binding sites were 58,600 molecules with the hybrid peptide and 52,400 molecules with YRGDS. These peptides inhibited fibrinogen binding to thrombin-stimulated platelets in a dose-dependent manner. The order of inhibitory potency of these peptides was as follows: fibrinogen models R: hybrid peptide > YRGDS > GQQHHLGGAKQAGDV (G15). The RGES peptide had no inhibitory activity. These three peptides inhibited binding of the anti-GP II b/III a monoclonal antibody (LJ-CP8) to platelets. The hybrid peptide showed the most potent inhibitory activity, with an IC50 of 48 µM. These results suggest that the linear combined RGDS and gamma chain peptide created with proline increases the affinity of binding to activated platelets.

Journal Article↗
PubMed1996

Novel synthetic peptides from the C-terminal heparin binding domain of fibronectin with heparin binding activity.

To identify a minimal peptide ligand that participates in recognition of heparin, we synthesized peptides extending a 29-kDa fragment in the C-terminal heparin binding domain of fibronectin. We obtained evidence that two peptides (designated D5 and D1) exhibit inhibitory activity on binding of the 29-kDa fragment to heparin-Sepharose CL 6B. It dose inhibitory studies, peptide D5 showed the potent inhibitory activity with IC50 of 210 +/- 37 microM. A new heparin binding site in the C-terminal heparin binding domain of fibronectin is demonstrated and provides a rationale for understanding the mechanism of cell adhesion and spreading.

Binding Sites↗