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Biomedical subjects

K Ikuta

Publications and source records attributed to K Ikuta.

At least 271 records · Page 15Linked to original sources
PubMed1992

Altered cell tropism and cytopathicity of feline immunodeficiency viruses in two different feline CD4-positive, CD8-negative cell lines.

Two interleukin-2-dependent feline CD4-positive and CD8-negative cell lines, MYA-1 and the newly established FeL-039, were used as host cells for infection with feline immunodeficiency virus (FIV). All FIV strains used, the Petaluma strain and several new isolates, were highly cytopathic to MYA-1. In contrast, the kinetics of FIV replication in FeL-039 differed greatly depending on the strain tested, i.e., noninfectious strain, highly cytopathic strain, and less cytopathic strain producing a persistent state for a long period. It appears, therefore, that cell tropism for FIV differed with each FIV strain tested even in T-cell lines showing similar cell surface phenotypes. Cytopathicity of FIV is evidently due to both the FIV strain and the host T cell.

Animals↗
PubMed1992

Lymphocyte development from stem cells.

Highly enriched pluripotent and multipotent hematopoietic stem cells (HSCs) are isolated from bone marrow and fetal liver as Thy-1loLin-Sca-1+ cells. Pluripotent HSCs express c-kit receptor on their surface, but the generation and proliferation of early fetal HSCs take place in the absence of steel factor. T precursor cells migrate into the fetal thymus by chemotactic mechanism. CD4lo precursors represent a newly defined phase of T-cell development in the thymus between the bone marrow-derived stem cells and the CD4-8- intrathymic precursors. Only fetal, but not adult, HSCs have the capacity to differentiate into V gamma 3+ and V gamma 4+ T cells under the fetal thymic microenvironment, and HSC themselves may lose some of their developmental potential during ontogeny. It is postulated that HSCs are the locus of a complicated but precise developmental clock that may determine both the time-dependent closure of some gene loci (e.g. V gamma 3 and V gamma 4 T cell receptor, and embryonic and fetal globin) and the activation of others (e.g. the N nucleotide insertion machinery).

Animals↗
PubMed1992

[Polycythemia vera terminating in chronic neutrophilic leukemia: studies on in vitro growth of hematopoietic progenitor cells].

A 57-year-old man, diagnosed as Polycythemia vera (PV), had been treated with administrations of Busulfan since 1984. Three years later, the number of neutrophils in peripheral blood increased to 50,000/microliters with progression of splenomegaly, and the case was diagnosed as Chronic neutrophilic leukemia (CNL) based on the criteria by Miura et al, in November, 1989. In spite of 6MP and Busulfan therapy, marked neutrophilia and splenomegaly progressed, and the patient died due to liver dysfunction in June of 1991. To clarify the pathophysiology of PV and CNL, we studied the in vitro growth kinetics of hematopoietic progenitor cells in bone marrow of this unique case and made a comparison with those of 4 cases of PV and 4 normal volunteers employing methylcellulose culture. As in other cases of PV, erythroid colonies were formed in culture of bone marrow from this patient without addition of erythropoietin. Furthermore, spontaneous colonies derived from CFU-GM and CFU-Mix increased remarkably in this case only. The results suggest that the hematopoietic abnormalities in this case involve the multipotent stem cells as well as erythroid and granuloid-macrophage progenitors.

Colony-Forming Units Assay↗
PubMed1992

[Recurrent pulmonary edema in a patient with acute lymphoblastic leukemia after syngeneic bone marrow transplantation].

Severe respiratory distress appeared in a 14-year-old girl with acute lymphoblastic leukemia 2 months after receiving syngeneic bone marrow transplantation (BMT) with a conditioning regimen of a high-dose of busulfan, etoposide and nimustine. Rapid body-weight gain and edema, especially in eyelids and lower-limbs, were also observed. Without any findings of heart failure nor GVHD, pulmonary edema was recognized on the chest roentgenogram. As soon as the diagnosis of pulmonary edema due to 'capillary leak syndrome' was suspected, the patient was treated with intravenous administration of diuretics, albumin and bolus methylprednisolone in combination of mechanical ventilation. Although the clinical manifestations were improved by the treatment, the disease recurred 5 weeks later. The patient was successfully treated by the same medications, and there has been no recurrence as of the sixth month after discontinuance of the therapy. At present, the mechanism of capillary leak syndrome is still undefined. In this case, however, we speculate that the conditioning regimen for BMT intensified the capillary disturbance initially caused by intensive chemotherapy since remission induction. Furthermore hypoalbuminemia due to severe anorexia might have enhanced the occurrence of the disease.

Adolescent↗
PubMed1991

The junctional modifications of a T cell receptor gamma chain are determined at the level of thymic precursors.

T precursors from fetal liver and adult bone marrow were compared for their ability to give rise to V gamma 4+ T cell development. Fetal thymic lobes were repopulated with fetal liver or adult bone marrow cells, and the organ-cultured thymocytes were analyzed for their T cell receptor expression by the polymerase chain reaction (PCR). Both day 14 fetal liver and adult bone marrow cells gave rise to thymocytes with V gamma 4-J gamma 1 transcripts. However, the average size of the PCR products derived from adult precursors was slightly larger than that from fetal precursors. DNA sequence analysis of the V gamma 4-J gamma 1 transcripts showed that early fetal liver precursors predominantly gave rise to thymocytes with the V gamma 4-J gamma 1 transcripts without N nucleotide insertion, while late fetal liver and adult marrow precursors predominantly gave rise to thymocytes with modified V gamma 4-J gamma 1 junctions. These results suggest the possibility that the level of the N nucleotide insertion is programmed at the level of thymic precursors. This study also supported the model presented previously that the developmental potential of hematopoietic stem cells may change during ontogeny.

Animals↗
PubMed1991

Mouse hematopoietic stem cells and the interaction of c-kit receptor and steel factor.

Hematopoietic stem cells (HSCs) are distinguished from other hematopoietic progenitors in bone marrow by their unique ability to undergo multilineage differentiation and self-renewal. Two mouse mutations, dominant spotting (W) and steel (Sl), have pleiotropic effects on hematopoiesis, gametogenesis, and melanoblast development. These two mutations have been shown to be intrinsic (W) and microenvironmental (Sl) defects. Recently, molecular studies revealed that the W and Sl loci encode the c-kit receptor and steel factor (SLF), respectively. The c-kit receptor is expressed on HSCs and hematopoietic progenitors, while SLF is produced by stromal cells. SLF acts on hematopoietic progenitors synergistically with other growth factors. Here we review the effect of these mutations on mouse hematopoiesis, and show that SLF acts on HSCs and other myeloerythroid progenitors, but that it, in our hands, does not play a critical role in HSC generation or self-renewal. Rather, SLF is the most potent co-mitogen (with IL-1, IL-3, IL-6, G-CSF, GM-CSF, or M-CSF) found that acts on these cells, but the effect of such treatments is the rather specific and massive expansion of myeloerythropoiesis, not lymphopoiesis, and perhaps at the expense of HSC self-renewal.

Animals↗
PubMed1991

Human immunodeficiency virus type 1 vif, vpr, and vpu mutants can produce persistently infected cells.

A series of human immunodeficiency virus type 1 (HIV-1) mutants in vif, vpr, vpu, and nef were constructed from an infectious plasmid (pNL 432) containing the full-length HIV-1 DNA by frameshift mutations. The capacities for replication and cell killing of these mutant viruses were examined in a clonal cell line (M 10) isolated from HTLV-I-transformed MT-4 cells. In all cases, the mutant viruses replicated, expressed HIV-1 antigens, and induced drastic cytopathic effects. However, some M 10 cells survived infection with vif, vpr, and vpu mutant viruses and became persistently HIV-1-infected, whereas no cells survived infection with the nef mutant as well as the wild-type virus. The HIV-1 particles produced from the surviving cells after infection with the vif, vpr, or vpu mutant viruses were fully replicative in M 10 cells without apparent cytopathic effects.

Cell Death↗
PubMed1991

Molecular cloning of a novel isolate of feline immunodeficiency virus biologically and genetically different from the original U.S. isolate.

The Japanese isolate (TM1 strain) of feline immunodeficiency virus (FIV) which replicates in a feline CD4 (fCD4)-positive lymphoblastoid cell line (MYA-1 cells) was molecularly cloned from extrachromosomal closed circular DNA. The restriction map of the clone, termed pFTM 191 complete genome (CG), showed a considerable difference from that of the U.S. isolate (Petaluma strain) of FIV. The sequence homology in the long terminal repeat between the TM1 and Petaluma strain was 82%. The pFTM 191 CG was biologically active after transfection into Crandell feline kidney cells which were permissive for replication of FIV Petaluma. However, the progeny virions could not reinfect fCD4-negative Crandell feline kidney cells but could infect fCD4-positive MYA-1 cells. When a specific-pathogen-free cat was inoculated with the virus derived from the pFTM 191 CG, the cat seroconverted within 8 weeks postinoculation and FIV was reisolated at 4, 8, and 20 weeks postinoculation. These results indicate the infectivity of the pFTM 191 CG in vivo.

Animals↗
PubMed1991

Noninfectious doughnut-shaped human immunodeficiency virus type 1 can induce syncytia mediated by fusion of the particles with CD4-positive cells.

A defective doughnut-shaped human immunodeficiency virus type 1 (HIV-1)-producing cell clone (designated as L-2) was isolated from persistently HIV-1-infected MT-4 cells. The syncytium-forming capacity of the cell and virus particle fractions was examined in human CD4-positive T cells. Several cell lines producing infectious HIV-1 particles, such as persistently HIV-1-infected MOLT-4 (MOLT-4/HIV-1) cells, were used as controls. Syncytia were formed within 20 h by the cell fraction of both L-2 and MOLT-4/HIV-1 and the virus particle fraction of L-2, but not MOLT-4/HIV-1. These formations were not affected by 3'-azido-3'-deoxythymidine (ZDV). In contrast, similar syncytium formation was first observed 2 days after the incubation of the virus particle fraction of MOLT-4/LAV-1 and this syncytium formation mediated by the cell fractions of MOLT-4/HIV-1 and L-2 or the virus particle fraction of L-2 differently.

Antibodies, Monoclonal↗
PubMed1991

Treatment of acute lymphoblastic leukemia in the Tokyo Children's Cancer Study Group--preliminary results of L84-11 protocol.

The Tokyo Children's Cancer Study Group (TCCSG) has performed prospective randomized controlled studies since 1984 for childhood acute lymphoblastic leukemia (ALL). Four hundred and ninety-eight newly diagnosed patients were treated with 5 different regimens designated as S1, S2 for a standard risk group (SRG), H1 and H2 for a high risk group (HRG) and HEX for an extremely high risk group of patients. We added intermediate-dose methotrexate as early intensification therapy in the S2 and H2 groups to reduce extramedullary and medullary relapses. Event-free survival of all patients at 4 years 6 months from the start of this regimen (median follow-up period 32 months) was 67.5%. The CNS relapse rate was significantly decreased to 2.2% compared to previously reported studies and our own experience. There were some unexpected complications of the CNS such as myelopathy and/or leukoencephalopathy. For the SRG early ID-MTX seemed to be useful to improve the prognosis, but triple intrathecal injections (TIT) should be limited in number. The 24Gy cranial irradiation (CRX) was effective but possibly excessive for the HRG. As evidenced by the success of the HEX group regimen, more intensive multi-drug consolidation in the early post-remission phase might be necessary to improve further the prognosis and to make it possible to shorten the treatment periods.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Establishment and characterization of a murine megakaryoblastic cell line growing in protein-free culture (L8057Y5).

A murine megakaryoblastic cell line growing in protein-free culture (L8057Y5) was established from an experimentally induced murine leukemia (MK8057). Most of the Y5 cells were small and blast-like, with 2-4N in DNA content. Also, large cells possessing a lobulated nucleus characteristic of megakaryocytes, which showed polyploidization to more than 4N up to 16N, were occasionally seen. Nearly 5% of the total number of Y5 cells were positive for acetylcholinesterase reaction. The survival time of C3H/He mice after injection with Y5 cells was longer than that of mice injected with the original MK8057 cells. The colony-forming ability of Y5 cells in the spleen of the lethally irradiated mouse was much lower, whereas the number of in vitro colonies derived from Y5 was greater than that of MK8057. The plating efficiency of colony formation in serum-free methylcellulose culture was higher at a low O2 tension. Conditioned medium of Y5 cells enhanced colony formation as well as 3H-TdR uptake by Y5 cells, which implies that Y5 cells may produce autocrine growth factor(s). mRNAs for IL-6, LIF, and INF-gamma were expressed in Y5 cells; these cytokines may have roles in the growth mechanisms of the cell line.

Animals↗
PubMed1991

[Cell differentiation action of 4'-epi-adriamycin in WEHI-3B myelomonocytic leukemia cells].

We studied the effect of 4'-epi-adriamycin on the differentiation of WEHI-3B (D+) murine myelomonocytic leukemia cell line (parent line) and WEHI-3B-MIT-R subline resistant to induction of differentiation by mitoxantrone. WEHI-3B(D+) cells were differentiated into mature granulocytes in suspension culture when exposed to 4'-epi-adriamycin regardless of the cell densities. The maximum differentiation rate was produced by 50 nM 4'-epi-adriamycin; at this concentration, approximately 40% of the cell population expressed a differentiated phenotype, as assessed by their ability to reduce nitroblue tetrazolium Induction of differentiation was observed by 4'-epi-adriamycin even at low cell densities (less than 10(5)/ml) that excluded the effects of autoinduction of differentiation. WEHI-3B-MIT-R cell line, which have a capacity of G-CSF-induced differentiation, was cross-resistance to 4'-epi-adriamycin. These results suggest that the mechanism of action differs from that of the induction of differentiation by G-CSF (which is known to show the activity by the secondary autoinduction of differentiation) and the differentiation induction is due to the direct action of 4'-epi-adriamycin.

Animals↗
PubMed1990

A developmental switch in thymic lymphocyte maturation potential occurs at the level of hematopoietic stem cells.

Hematopoietic stem cells (HSCs) isolated from mouse fetal liver, like adult HSCs, are Thy-1lo Lin- Sca-1+. Donor-derived V gamma 3+ T cells were detected in fetal thymic lobes repopulated in vitro with fetal liver HSCs, but not in those with adult bone marrow HSCs. Single clonogenic fetal HSCs gave rise to thymic progeny that include V gamma 3+, other gamma delta+, and alpha beta+ T cells. No V gamma 3+ T cells were detected in adult thymus injected intrathymically with either fetal or adult HSCs. These results support the hypothesis that only fetal HSCs have the capacity to differentiate into V gamma 3+ T cells in the fetal thymic microenvironment and that the developmental potential of HSCs may change during ontogeny.

Animals↗
PubMed1990

The budding of defective human immunodeficiency virus type 1 (HIV-1) particles from cell clones persistently infected with HIV-1.

Three cell clones producing large numbers of infectious or noninfectious particles of human immunodeficiency virus type 1 (HIV-1), designated M 10/LAV-2, M 16/LAV-3, and MT/LAV-17, were isolated from persistently HIV-1-infected MT-4 cells. In M 10/LAV-2, the HIV-1 proteins were defective in the cleavage of gag precursor protein, and the particles were doughnut-shaped with a double-ring structure. These particles were produced by budding at the cell surface from crescentic structures followed by the formation of double-ring structures. The viral proteins in M 16/LAV-3 were defective in the cleavage of env precursor protein. The morphology of the virus particles was intact, and an electron dense bar-shaped core was seen inside a single-ring enveloped structure. The intact particles were released from the cell surface by a budding process in which crescent shape structures first appeared at the cell membrane, then subsequently just before release matured to a complete structure with an electron dense core. In MT/LAV-17, the synthesis of HIV-1 proteins was normal, and the particles were teardrop-shaped with an intact core structure. These particles were produced by budding with an electron dense core at the cell surface. Thus, it was suggested that the morphological maturation of HIV-1 particles was completed just before release from the cell surface in several cell clones producing HIV-1 particles of different morphology.

Antibodies, Monoclonal↗