Biomedical subjects

K Ikuta

Publications and source records attributed to K Ikuta.

At least 109 records · Page 6Linked to original sources

PubMed1999

Borna disease virus infection in two family clusters of patients with chronic fatigue syndrome.

A high rate of Borna disease virus (BDV) infection has been demonstrated in patients with chronic fatigue syndrome (CFS). Herein, we focused on BDV infection in two family clusters of patients with CFS: a father, mother, two sons and one daughter (family #1); and a father, mother, two daughters and one son (family #2). All members, except for the elder son in family #1 and the father and son in family #2, were diagnosed with CFS. The results supported that all the family members with CFS were infected with BDV, as evidenced by the presence of antibodies to viral p40, p24 and/or gp18 and BDV p24 RNA in peripheral blood mononuclear cells. The healthy members, except for the father of family #2 who was positive for antibody to p24, were all negative by both assays. Follow-up studies in family #1 continued to reveal BDV antibodies and BDV RNA, except in the mother, who lost the RNA upon slight recovery from the disease.

Amino Acid Sequence↗

PubMed1999

Increase of serum des-gamma-carboxy prothrombin in alcoholic liver disease without hepatocellular carcinoma.

The purpose of this study is to determine serum des-gamma-carboxy prothrombin (DCP) levels in benign liver diseases by a new sensitive method, and to demonstrate the elevation of serum DCP in alcoholic liver disease (ALD) without hepatocellular carcinoma (HCC). Median values of serum DCP were 16.2 mAU/ml (range: 3.2 to 1570 mAU/ml) in ALD and 16.7 mAU/ml (1.2 to 75.4 mAU/ml) in viral liver disease (VLD). Using the cut-off value of 40 mAU/ml as a tumor marker for HCC, 21% (11/52) was positive in ALD and 2% (1/57) was positive in VLD (p = 0.0014, Fisher's exact probability test), and 27% (9/33) was positive in alcoholic liver cirrhosis and 3% (1/39) was positive in viral liver cirrhosis (p = 0.0042, Fisher's exact probability test). The positive rate of DCP was significantly (p < 0.001, Spearman's rank correlation test) correlated with the severity of liver disease in ALD. Serum vitamin K level was not decreased in cases with ALD. In a demonstrable case, serum DCP was decreased after abstinence and was increased again after the beginning of ethanol intake, suggesting the involvement of ethanol to the elevation of serum DCP in ALD. In conclusion, serum DCP was significantly elevated in ALD, compared with VLD, although the mechanism of the elevation of DCP was not clarified. Ethanol intake may act, in part, on the increase of serum DCP in ALD.

Aged↗

PubMed1999

Fine structure and morphogenesis of Borna disease virus.

Borna disease virus (BDV), a negative nonsegmented single-stranded RNA virus, has not been fully characterized morphologically. Here we present what is to our knowledge the first data on the fine ultrastructure and morphogenesis of BDV. The supernatant of MDCK cells persistently infected with BDV treated with n-butyrate contained many virus-like particles and more BDV-specific RNA than that of untreated samples. The particles were spherical, enveloped, and approximately 130 nm in diameter; had spikes 7 nm in length; and reacted with BDV p40 antibody. A thin nucleocapsid, 4 nm in width, was present peripherally in contrast to the thick nucleocapsid of hemagglutinating virus of Japan. The BDV particles reproduced by budding on the cell surface.

Animals↗

PubMed1999

The YXXL sequences of a transmembrane protein of bovine leukemia virus are required for viral entry and incorporation of viral envelope protein into virions.

The cytoplasmic domain of an envelope transmembrane glycoprotein (gp30) of bovine leukemia virus (BLV) has two overlapping copies of the (YXXL)2 motif. The N-terminal motif has been implicated in in vitro signal transduction pathways from the external to the intracellular compartment and is also involved in infection and maintenance of high viral loads in sheep that have been experimentally infected with BLV. To determine the role of YXXL sequences in the replication of BLV in vitro, we changed the tyrosine or leucine residues of the N-terminal motif in an infectious molecular clone of BLV, pBLV-IF, to alanine to produce mutated proviruses designated Y487A, L490A, Y498A, L501A, and Y487/498A. Transient transfection of African green monkey kidney COS-1 cells with proviral DNAs that encoded wild-type and mutant sequences revealed that all of the mutated proviral DNAs synthesized mature envelope proteins and released virus particles into the growth medium. However, serial passages of fetal lamb kidney (FLK) cells, which are sensitive to infection with BLV, after transient transfection revealed that mutation of a second tyrosine residue in the N-terminal motif completely prevented the propagation of the virus. Similarly, Y498A and Y487/498A mutant BLV that was produced by the stably transfected COS-1 cells exhibited significantly reduced levels of cell-free virion-mediated transmission. Analysis of the protein compositions of mutant viruses demonstrated that lower levels of envelope protein were incorporated by two of the mutant virions than by wild-type and other mutant virions. Furthermore, a mutation of a second tyrosine residue decreased the specific binding of BLV particles to FLK cells and the capacity for viral penetration. Our data indicate that the YXXL sequences play critical roles in both viral entry and the incorporation of viral envelope protein into the virion during the life cycle of BLV.

Amino Acid Sequence↗

PubMed1999

[Screening test for hematopoietic stem cells in umbilical cord blood with the SE-9000 automated hematology analyzer].

The immature information IMI channel on an SE-9000 automated hematology analyzer was used for detection of stem cells in cord blood and the results were compared with other standard methods, including flow cytometry analysis and progenitor assays. After the removal of red blood cells, the IMI count in cord blood samples significantly correlated with the number of CD34+ cells (r = 0.810), CFU-GM (r = 0.606) and BFU-E (r = 0.961). The cell count in hematopoietic progenitor cell (HPC) area also showed a correlation with CD34+ cell number (r = 0.722), but to a lesser extent than the IMI count; no significant correlations were observed with the numbers of progenitor cells. Cord blood contained higher fractions of CD34+/CD38- and CD34+/CD117+ cells representative of immature subclasses of progenitor cells. This might explain the difference in the HPC module results for the cord blood and peripheral blood stem cell samples. A higher coefficient of correlation was obtained with leukocyte suspensions than with whole blood samples. These results demonstrated the usefulness of IMI-positive cell measurement as a stem cell screening test for cord blood banking.

Antigens, CD34↗

PubMed1999

Reverse transcriptase (RT)-independent as well as RT-dependent HIV-1 replication exists in syncytia following cell fusion.

We studied the role of reverse transcriptase (RT) in human immunodeficiency virus (HIV)-1 replication in syncytia following cell fusion. A chronically HIV-1-infected MOLT-4 (MOLT-4/IIIB) cells allow HIV-1 replication and induce syncytium formation between uninfected MOLT-4 cells. AZT (3'-azido-3'-deoxythymidine, 1 microM) inhibited neither HIV-1 replication in MOLT-4/IIIB cells nor the syncytium formation induced by concultivation of MOLT-4/IIIB cells with uninfected MOLT-4 cells. In the supernatant of the syncytium containing culture a remarkably higher titer of p24 antigen was produced than in that of MOLT/IIIB cell culture. AZT inhibited p24 antigen production by HIV-1 in the syncytia to levels to comparable to that in MOLT-4/IIIB cells which were treated with AZT. In addition, p24 production by HIV-1 in the syncytia formed by cocultivation of CL-2 cells, which are chronically infected with HIV-1 but lack functional RT, with uninfected MOLT-4 cells was not different from that in CL-2 cells alone. The results suggest that HIV-1 RT plays an important role in HIV-1 replication within the syncytia but an RT-independent replication process which is essential for syncytium formation also exists in the syncytia. These results indicate that not only RT inhibitors but also inhibitors of syncytium formation are essential for anti-HIV therapy.

Cell Line↗

PubMed1998

Producer cell-dependent requirement of the Nef protein for efficient entry of HIV-1 into cells.

A proviral nef gene mutant of human immunodeficiency virus type 1 (HIV-1) was evaluated for its defective early replication step. Virus stocks were prepared from six CD4-positive and -negative cell lines transfected with wild-type (wt) or the nef mutant clone and inoculated into two target CD4-positive cell lines to monitor the efficiency of viral entry process. The nef mutant virions produced in one cell line exhibited a severe defect in the entry process, although those produced in the other five cell lines were only slightly less efficient than the wt virions at entering into cells. These results have demonstrated that the HIV-1 Nef is critical for efficient viral entry in a producer cell-dependent manner.

CD4-Positive T-Lymphocytes↗

PubMed1998

Impaired anaphylactic responses with intact sensitivity to endotoxin in mice lacking a platelet-activating factor receptor.

Platelet-activating factor (PAF) is a potent phospholipid mediator with diverse biological activities in addition to its well-known ability to stimulate platelet aggregation. Pharmacologic studies had suggested a role for PAF in pregnancy, neuronal cell migration, anaphylaxis, and endotoxic shock. Here we show that disruption of the PAF receptor gene in mice caused a marked reduction in systemic anaphylactic symptoms. Unexpectedly, however, the PAF receptor-deficient mice developed normally, were fertile, and remained sensitive to bacterial endotoxin. These mutant mice clearly show that PAF plays a dominant role in eliciting anaphylaxis, but that it is not essential for reproduction, brain development, or endotoxic shock.

Anaphylaxis↗

PubMed1998

Transmission and propagation in cell culture of virus produced by cells transfected with an infectious molecular clone of bovine leukemia virus.

A full-length molecular clone of bovine leukemia virus (BLV) pBLV-IF with two copies of a long terminal repeat (LTR) was constructed from a previously isolated, covalently closed, circular DNA clone, pB6490, that has one copy of the LTR and the pX region split at an EcoRI site. This molecular clone directed the synthesis of viral proteins and the induction of syncytia in transiently transfected cells. In addition, virus particles were released into the culture medium. Serial passages of transient transfectants also resulted in propagation of BLV. After transfection of five cell lines with linearized pBLV-IF and a neomycin-resistance gene, BLV-producing transfectants were established in cell lines COS-1 and 23CLN that did not form syncytia upon expression of BLV. In HeLa and FLK cells, BLV produced by a stable COS-1 transfectant was transmitted by both cell-free and cell-to-cell infection. Thus, pBLV-IF encoded an infectious provirus that successfully induced primary and secondary infections. This study indicates that the infectious molecular clone and the virus-producing transfectants could be useful for further examination of the biological properties of BLV.

Animals↗

PubMed1998

Nuclear targeting activity associated with the amino terminal region of the Borna disease virus nucleoprotein.

The Borna disease virus (BDV) replicates in the nucleus. The viral p40 protein (N), which is found abundantly in the nucleus in BDV-infected cells, may play an important role in virus replication. To analyze the amino acid residues involved in the nuclear targeting of BDV N, a series of eukaryotic expression plasmids encoding deletion mutants of N was constructed and transfected into COS-7 cells. In indirect immunofluorescence assays with a rabbit anti-BDV N antiserum, wild-type N was located in the nucleus of transfected cells in the absence of other viral constituents. In contrast, mutants lacking the 13 NH2-terminal amino acid residues 1MPPKRRLVDDADA13 in common gave a cytoplasmic localization pattern. Similarly, a mutant with substitution of 4KRR6 by 4NSG6 was retained in the cytoplasm. Furthermore, a nonapeptide, 3PKRRLVDDA11, derived from the NH2-terminal region of N conferred nuclear targeting activity to beta-galactosidase, which normally resides in the cytoplasm. Thus, we have identified the nuclear targeting signal of the BDV N and narrowed it to the NH2-terminal region where 4KRR6 basic amino acid residues are located.

Animals↗

PubMed1998

Two differing salmon GnRH precursor mRNAs are co-expressed in the brain of sockeye salmon.

The localization of two salmon-type gonadotropin-releasing hormone (sGnRH) precursors, pro-sGnRH-I (short type) and pro-sGnRH-II (long type), was investigated by using in situ hybridization techniques in the brain of the landlocked sockeye salmon, Oncorhynchus nerka. We used 30-mer oligonucleotide probes complementary to pro-sGnRH-I and pro-sGnRH-II cDNA. No significant differences were observed in the localization of sGnRH neurons expressing pro-sGnRH-I and pro-sGnRH-II mRNAs; both were expressed in the olfactory nerve, the olfactory bulbs, the regions between the olfactory bulb and telencephalon, the ventral telencephalon, the preoptic area, and the hypothalamus. Almost all sGnRH neurons examined co-expressed both precursors. The expression of two sGnRH precursors in the same neuron and the wide distribution of such neurons in the brain suggest that there are no functional differences between the two precursors.

Animals↗

PubMed1998

Ontogenic development of salmon GnRH and chicken GnRH-II systems in the brain of masu salmon (Oncorhynchus masou).

Ontogenic development of salmon gonadotropin-releasing hormone (GnRH) and chicken GnRH-II systems in masu salmon (Oncorhynchus masou) was examined. Salmon GnRH was first detected by radioimmunoassay in the embryo on day 36 after fertilization. Salmon GnRH-immunoreactive fibers were detected initially by immunocytochemistry in the vicinity of the olfactory placode of the embryo (day 36) and were distributed widely in the brain as well as in the pituitary gland of fish just after hatching (day 80). Salmon GnRH-immunoreactive neuronal somata were first detected about 6 months after fertilization in the rostroventral brain area, ranging from the olfactory nerve to the preoptic area. Salmon GnRH neuronal somata were detected earlier by in situ hybridization than by immunocytochemistry. Neuronal somata expressing salmon GnRH mRNA were first detected in the vicinity of the olfactory epithelium on day 40 and then were seen to be migrating from the olfactory epithelium, along the olfactory nerve, on day 60 and in the transitional area between olfactory nerve and olfactory bulb on day 80. In the brain, these neurons were first detected in the ventral olfactory bulb on day 80, and thereafter they were also detected in the caudal brain regions. The chicken GnRH-II system was detected later than the salmon GnRH system; chicken GnRH-II was first detected by radioimmunoassay on day 57, and chicken GnRH-II-immunoreactive fibers were first detected on day 67. Chicken GnRH-II-immunoreactive neuronal somata were not detected during the observation period. These results suggest that salmon GnRH neurons derive from the olfactory placode and then migrate into the brain and that salmon GnRH is synthesized before chicken GnRH-II.

Animals↗

PubMed1998

Reduced expression and rare genomic alteration of nm23-H1 in human hepatocellular carcinoma and hepatoma cell lines.

We investigated the expression and genomic alteration of nm23-H1 (which encodes a nucleoside diphosphate, kinase A) in 12 human hepatocellular carcinomas (HCCs) and four hepatoma cell lines. The expression of nm23-H1 protein was significantly reduced in HCCs with intrahepatic metastasis (72%) compared with expression in HCCs without intrahepatic metastasis (38%). However, in two of three HCCs examined that had marked reduction of nm23-H1 protein, the nm23-H1 mRNA level was not reduced. A hepatoma cell line, HLF (phenotype, poorly differentiated carcinoma) revealed marked reduction of nm23-H1 protein compared with two other hepatoma cell lines, HuH-1 and HuH-2, although the mRNA level was similar in the three cell lines. No allelic deletion of the nm23-H1 gene was detected in the 12 HCCs examined. No point mutation in the coding region of the nm23-H1 gene was observed in any of the 12 HCCs or the four hepatoma cell lines. These findings suggest that: (i) the expression of nm23-H1 protein is inversely associated with high metastatic potential of HCC, (ii) regulation of nm23-H1 expression may occasionally occur at both the transcriptional and post-transcriptional levels in HCC; and (iii) genomic alteration of nm23-H1 is a rare event in HCC.

Adult↗

PubMed1998

A specific T-cell subset with CD4+/CD38- markers derived from HIV-1 carriers induces apoptosis in healthy donor-derived T-lymphocytes.

Apoptosis is an important mechanism of human immunodeficiency virus type 1 (HIV-1)-induced T-cell depletion. Our recent findings revealed mitogenic stimulation-dependent apoptosis induction in healthy donor-derived peripheral blood T-lymphocytes after adsorption with defective HIV-1 particles through acquirement by a subset of CD4+/CD38- cells of specific killer function. Based on these in vitro observations, we have extended the significance of this killing activity of CD4+/CD38- cells directly derived from HIV-1 carriers. The CD4+/CD38- cells from HIV-1-positive individuals showed significantly higher cell-killing activities than those from HIV-1-negative donors by co-culture with allogeneic resting T-cells after mitogenic stimulation. Furthermore, most of the samples induced apoptosis in a Fas-dependent manner. Thus, it is suggested that HIV-1 infection-related apoptosis is triggered by inappropriate activation of a certain resting T-cell subset, presumably due to adsorption with HIV-1 particles.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Development of peptide vaccines inducing production of neutralizing antibodies against HIV-1 viruses in HLA-DQ6 mice.

Peptide vaccines against HIV-1 were prepared according to the cassette theory that we had proposed previously. An amino acid sequence of B subtype consensus of the HIV-1 V3 region was introduced into the MHC binding component with a supermotif for various MHC class II. The peptide vaccines induced T-cell responses in the DQ6 mice in which only DQ6 molecules were expressed as MHC class II. By contrast, an original V3 peptide including the consensus sequence was non-immunogenic in the DQ6 mice. Antibodies obtained from the DQ6 mice immunized with the peptide vaccines neutralized laboratory B subtype strains of HIV-1 in vitro. It may be anticipated that these peptide vaccines protect infection of HIV-1 in DQ6 positive individuals.

AIDS Vaccines↗

PubMed1998

Loss of heterozygosity of NF1 gene in juvenile chronic myelogenous leukemia with neurofibromatosis type 1.

To investigate a genetic relation between juvenile chronic myelogenous leukemia (JCML) and neurofibromatosis type 1 (NF-1), we analyzed the NF1 gene in the leukemic cells of a JCML patient with NF-1. We found a point mutation in exon 29 of one allele and a deletion of the other normal allele in the leukemic cells. The point mutation is considered a germline mutation because it was also detected in fibroblasts obtained from the bone marrow of the patient and the peripheral blood mononuclear cells from a sibling. A loss of heterozygosity of NF1 gene may contribute to the progression of leukemia in NF-1 patients.

Alleles↗

PubMed1998

Unrelated umbilical cord-blood stem cell transplantation: a report from Kanagawa Cord Blood Bank, Japan.

Umbilical cord-blood (CB) has been used as a source of hematopoietic stem cells in pediatric patients with sibling donors. As a result of the success with CB transplantation from sibling donors, pilot programs for the banking of unrelated donor CB were initiated in the organization of Kanagawa Cord Blood Bank, Japan in 1995. As of December 1997, unrelated donor CB was used to reconstitute hematopoiesis in seven patients aged 0.7-12.8 years, weighing 7-36 kg with high-risk leukemia (n = 5), myelodysplastic syndrome (n = 1), and immunodeficiency syndrome (n = 1). Engraftment of CB was achieved in six patients. The absolute neutrophil count reached 500/microliter in a median of 27 days; a platelet count of 20,000/microliter was reached by a median of 64 days in three patients who could be evaluated. Five patients are currently surviving. Grade I GVHD developed in three patients and grade III in one patient; no GVHD developed in three patients. Although only a small number of patients have been studied and the period of observation is too short to determine long-term survival, HLA-matched or HLA-mismatched CB from unrelated donors can provide an alternative source of hematopoietic reconstitution for clinical transplantation.

Blood Banks↗

PubMed1998

A novel mutation found in an adrenoleukodystrophy patient who underwent bone marrow transplantation.

We identified a novel mutation, L322P, in a patient with X-linked adrenoleukodystrophy (ALD) who underwent bone marrow transplantation (BMT). An identification of the ALD gene mutation enabled us to employ an approach not dependent on the use of radioisotopes for detecting mixed chimerism. This assay could show more than 99.0% of the patient's peripheral white blood cells were replaced by the donor's cells.

Adrenoleukodystrophy↗