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Biomedical subjects

T Nakahata

Publications and source records attributed to T Nakahata.

At least 37 records · Page 2Linked to original sources
PubMed2001

Flt-1, vascular endothelial growth factor receptor 1, is a novel cell surface marker for the lineage of monocyte-macrophages in humans.

Flt-1, also known as vascular endothelial growth factor receptor 1 (VEGFR-1), is a high-affinity tyrosine kinase receptor for VEGF and is expressed almost exclusively on vascular endothelial cells. As an exception, Flt-1 transcript was recently found to be expressed in human peripheral blood monocytes. However, the protein of the Flt-1 receptor on the cell surface of monocytes is yet to be identified, and whether the Flt-1 protein is expressed during the differentiation of monocyte-macrophage lineage cells has not been examined. Using monoclonal antibodies against 2 different antigenic epitopes on the Flt-1 extracellular domain, this study found that the major population of the monocyte-marker CD97+ cells in human peripheral blood express Flt-1 as a cell surface molecule. VEGFR-2 (KDR/Flk-1) was not expressed at detectable levels in these cells. An Flt-1 neutralizing monoclonal antibody significantly suppressed VEGF-induced migration of the monocytes, suggesting an important role for Flt-1 in the biologic function of monocytes. Furthermore, CD34+ cells in human cord blood, originally negative for the Flt-1 expression, differentiated into Flt-1+ cells in association with the appearance of monocyte-macrophage markers after a 2-week culture in the presence of hematopoietic cytokines. In addition, the Flt-1+ CD11b+ cell fraction from CD34+ cells was found to efficiently differentiate into multinuclear osteoclasts in the presence of macrophage colony-stimulating factor and osteoclast differentiation factor. These results strongly suggest that Flt-1 is a novel cell surface marker as well as a biologically functional molecule for monocyte-macrophage lineages in humans.

3T3 Cells↗
PubMed2001

CD34 expression on long-term repopulating hematopoietic stem cells changes during developmental stages.

The CD34 antigen serves as an important marker for primitive hematopoietic cells in therapeutic transplantation of hematopoietic stem cells (HSC) and gene therapy, but it has remained an open question as to whether or not most HSC express CD34. Using a competitive long-term reconstitution assay, the results of this study confirm developmental changes in CD34 expression on murine HSC. In fetuses and neonates, CD34 was expressed on Lin(-)c-Kit(+) long-term repopulating HSC of bone marrow (BM), liver, and spleen. However, CD34 expression on HSC decreased with aging, and in mice older than 10 weeks, HSC were most enriched in the Lin(-)c-Kit(+)CD34(-) marrow cell fraction. A second transplantation was performed from primary recipients who were transplanted with neonatal Lin(-)c-Kit(+) CD34(high) HSC marrow. Although donor-type HSC resided in CD34-expressing cell fraction in BM cells of the first recipients 4 weeks after the first transplantation, the stem cell activity had shifted to Lin(-)c-Kit(+)CD34(-) cells after 16 weeks, indicating that adult Lin(-)c-Kit(+)CD34(-) HSC are the progeny of neonatal CD34-expresssing HSC. Assays for colony-forming cells showed that hematopoietic progenitor cells, unlike HSC, continue to express CD34 throughout murine development. The present findings are important because the clinical application of HSC can be extended, in particular as related to CD34-enriched HSC and umbilical cord blood HSC.

Age Factors↗
PubMed2001

Ex vivo expansion of human hematopoietic stem cells.

There has been great interest in the ex vivo expansion of human long-term repopulating hematopoietic stem cells (LTR-HSCs) for a variety of clinical applications such as umbilical cord blood transplantation. The glucoprotein130 signal, activated by a complex of interleukin 6 (IL-6) and soluble IL-6 receptor (IL-6/sIL-6R), acts dramatically in synergy with the c-Kit or Flk2/Flt3 signal to expand immature human HSCs. We demonstrate a significant ex vivo expansion of human LTR-HSCs capable of repopulating in newly discovered nonobese diabetes/Shi-severe combined immunodeficient (NOD/Shi-SCID) mice. The proportion of human CD45+ cells in recipient marrow was 10 times higher in animals receiving the cultured cells with stem cell factor, Flk2/Flt3 ligand, thrombopoietin, and IL-6/sIL-6R than in those receiving comparable numbers of fresh cord blood CD34+ cells. The expansion rate provided by this combination was estimated to be 4.2-fold by a limiting dilution method. Addition of IL-3 to the culture with the cytokine combination abrogated the repopulating ability of the expanded cells. The culture method with the IL-6/sIL-6R complex and other cytokines may pave the way for ex vivo expansion of human transplantable HSCs suitable for clinical applications.

Animals↗
PubMed2001

Current knowledge on the pathophysiology of Fanconi anemia: from genes to phenotypes.

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, bone marrow failure, and leukemia susceptibility. FA cells show chromosome instability and hypersensitivity to DNA cross-linking agents such as mitomycin C. Recent studies indicate that there are at least 8 genetically distinct FA groups (A, B, C, D1, D2, E, F, G). To date, 6 genes (for A, C, D2, E, F, and G) have been cloned. In this review, we describe the structures and functions of FA proteins. Increasing evidence indicates that the multiple FA proteins cooperate in a biochemical pathway and/or a multimer complex. FANCD2, a downstream component of the FA pathway, has recently been shown to be ubiquitinated in response to DNA damage and to translocate to nuclear foci containing BRCA1, a breast cancer susceptibility gene product, suggesting a role for this protein in DNA repair functions. We also describe 2 emerging issues: genotype-phenotype relationships and mosaicism. The FA pathway is likely to play a critical role as a caretaker of genomic integrity in hematopoietic stem cells. Clarifying the molecular basis of this disease may provide new insights into the pathogenesis of bone marrow failure syndromes and myeloid malignancies.

Adolescent↗
PubMed2001

Repetitious appearance and disappearance of different kinds of clonal cytogenetic abnormalities after allogeneic bone marrow transplantation.

We report a childhood case that showed the repeated appearance and disappearance of various kinds of cytogenetic abnormalities (CA) for 5.5 years after allogeneic bone marrow transplantation (BMT). The patient underwent allogeneic BMT from an HLA-matched unrelated donor during the second complete remission of acute lymphoblastic leukemia. The conditioning regimen for BMT consisted of etoposide, cyclophosphamide, anti-human thymocyte immunoglobulin, and total body irradiation. There were no leukemic relapses or secondary acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) since the BMT. The CA occurred from residual recipient cells, which were damaged by chemotherapy or radiation prior to BMT. Although previous studies about post-BMT CA had reported the continuous emergence of identical clones, the present case showed the appearance of one different type of clone after another. Although the appearance of different types of CA may mean that these clones did not obtain any growth advantages, it may be a sign of genomic instability, which is probably a risk factor for the development of secondary AML/MDS.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Repeat renal biopsy in a girl with tubulointerstitial nephritis and uveitis syndrome.

A Japanese girl aged 8 years who presented with a 2-month history of uveitis subsequently developed tubulointerstitial nephritis. A percutaneous renal biopsy revealed massive interstitial mononuclear cell infiltrates consisting of CD4-positive T cells. Despite administration of topical corticosteroids, the ocular symptoms persisted. Systemic corticosteroid therapy dramatically reduced the ocular symptoms and urinary beta2-microglobulin (beta 2MG) concentration. However, reducing the prednisolone dosage induced recurrence of uveitis associated with increased levels of urinary beta 2MG. The CD4-positive T cell infiltration persisted in the second renal biopsy performed 6 months after the first renal biopsy. These observations suggest that the interstitial cell infiltration persists for a relatively long time in a proportion of patients with tubulointerstitial nephritis and uveitis syndrome (TINU). Although the renal outcome of TINU has been reported to be favorable, prolonged interstitial cell infiltration may affect long-term renal outcome. Selected patients with TINU should be followed with close observation.

Adrenal Cortex Hormones↗
PubMed2001

Intracranial aneurysms in Ehlers-Danlos syndrome type IV in early childhood.

Ehlers-Danlos syndrome type IV is of special interest to neurologists because of the risk of cerebrovascular complications. We describe a 5-year-old female with Ehlers-Danlos syndrome type IV, demonstrating multiple intracranial aneurysms and right middle cerebral artery stenosis. The diagnosis of Ehlers-Danlos syndrome type IV was confirmed by electron microscopic examination of a skin biopsy. To our knowledge, this is the youngest reported patient with intracranial aneurysms associated with the Ehlers-Danlos syndrome type IV. Ehlers-Danlos syndrome type IV should be considered in the differential diagnosis of cerebrovascular disorder and stroke in early childhood.

Age of Onset↗
PubMed2001

Prompt and durable hematopoietic reconstitution by unrelated cord blood transplantation in a child with Fanconi anemia.

We describe here the case of an 8-year-old girl with Fanconi anemia (FA) whose hematopoiesis was successfully restored by unrelated umbilical cord blood (UCB) transplantation. The patient became resistant to androgen therapy, and developed intracranial hemorrhage and dyserythropoiesis. Her hematopoietic recovery after the transplantation was excellent and a complete chimerism has been durably maintained. UCB should be considered as a stem cell source for transplantation when a patient with FA does not have an HLA-identical unaffected sibling donor.

Child, Preschool↗
PubMed2001

Myelodysplastic syndrome in childhood: a retrospective study of 189 patients in Japan.

We report a retrospective analysis of children with myelodysplastic syndrome (MDS) diagnosed between 1990 and 1997 in Japan. In total, 189 patients were enrolled: 122 cases of primary MDS (26 RA, 18 RAEB, 25 RAEBt, 53 CMML/JMML), 24 cases with constitutional predisposition to MDS, and 43 cases of therapy-related MDS (t-MDS). The frequency of pediatric MDS was estimated to be 7.7% of all leukemias. Cytogenetic abnormalities were observed in 41% of primary MDS and 90% of t-MDS cases. The 4-year survival rate, estimated by Kaplan-Meier analysis, for primary RA was 78.9%, while other types of MDS and JMML had rates lower than 40%, and t-MDS showed an even more unfavorable prognosis. In primary MDS, the survival rate of patients with cytogenetic abnormalities was significantly lower. Among prognostic variables by IPSS, only the cytogenetic pattern was useful for predicting outcome in childhood MDS. There was no apparent advantage to chemotherapy for RA, and the survival rate in patients with primary RA, JMML, or t-MDS receiving stem cell transplantation was significantly higher. More precise designs of our diagnostic and classification systems, as well as therapeutic trials in large-scale prospective studies, are necessary for further improvements in MDS outcome.

Adolescent↗
PubMed2001

Inhibitory effect of interleukin 3 on early development of human B-lymphopoiesis.

Interleukin 3 (IL-3) is known as a stimulator of proliferation and differentiation of non-lymphoid cells, but information about the activity of IL-3 in lymphopoiesis is limited. In the present study, we examined the effect of IL-3 on human B-lymphopoiesis using the co-culture system on a murine stromal cell line, MS-5, with stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF). Although a large number of CD45+CD19+ B cells were generated in the co-culture of cord blood CD34+ cells, the addition of IL-3 to the co-culture suppressed the B-cell generation in a dose-dependent manner. In the co-culture, CD34+IL-3 receptor alpha-chain (IL-3Ralpha)+ cells, but not IL-3Ralpha- cells, produced B cells, and IL-3 suppressed the B-cell generation from CD34+IL-3Ralpha+ cells, suggesting that IL-3 exerts an inhibitory effect through the binding to IL-3Ralpha on CD34+ cells. Because the delayed addition of IL-3 and the short-term exposure to IL-3 showed that IL-3 acted as an inhibitor at an early stage of B-cell development from CD34+ cells, before the generation of CD19+ B cells, the effect of IL-3 on the early development of B cells from immature CD34+CD38- cells was examined. Individual colonies, produced from clone-sorted CD34+CD38- cells by SCF, thrombopoietin and a complex of IL-6/soluble IL-6R with or without IL-3, were divided into two fractions and analysed for B-cell potential using co-culture on MS-5 with SCF and G-CSF, and haematopoietic potential using methylcellulose clonal culture. Although some colonies cultured without IL-3 showed both B-cell and haematopoietic potential, all the colonies cultured with IL-3 showed only haematopoietic potential. These results indicate that IL-3 has an inhibitory effect on the B-cell generation from human lymphohaematopoietic progenitor cells.

Animals↗
PubMed2001

Role of the microenvironment of the embryonic aorta-gonad-mesonephros region in hematopoiesis.

Although various cytokines, growth factors, and chemokines are known to regulate hematopoiesis, expansion of hematopoietic stem cells (HSCs) in vitro with the use of such agents has proved problematic. Stromal cells are major components of the microenvironment that surrounds hematopoietic cells and are thought to play an important role in hematopoiesis in vivo. Co-culture of HSCs with stromal cells promotes hematopoiesis and self-renewal of HSCs. Definitive hematopoietic cells first appear during mammalian embryonic development in the aorta-gonad-mesonephros (AGM) region, and it is therefore thought that the microenvironment of this region plays an important role in HSC ontogeny. We have adopted two approaches to studying the contribution of the AGM microenvironment to hematopoiesis. In the first approach, we have developed an in vitro culture system for mouse AGM explants. Hematopoiesis is enhanced in such cultures by the presence of the combination of stem cell factor (SCF), basic fibroblast growth factor, leukemia inhibitory factor, and oncostatin M (SFLO culture). However, transplantation assays revealed that HSCs capable of long-term reconstitution of the hematopoietic compartment of irradiated mice (LTR-HSCs) do not expand in AGM-SFLO cultures; rather, these cultures appear to provide a favorable microenvironment for hematogenic angioblasts that are precursors of both endothelial and hematopoietic cells. In our second approach, we have established various stromal cell lines from the mouse AGM region. The AGM-S3 cell line supports human and mouse primitive hematopoietic cells as well as mouse LTR-HSCs. Maintenance of LTR-HSCs is mediated by a mechanism other than SCF signaling through its receptor (c-Kit). These two in vitro approaches should prove useful for further elucidation of the mechanisms that underlie hematopoiesis and HSC self-renewal.

Animals↗
PubMed2001

Thrombotic stroke in a child with diarrhea-associated hemolytic-uremic syndrome with a good recovery.

A boy aged 3.5 years with post-diarrheal hemolytic-uremic syndrome (HUS) was referred to our hospital because of convulsion and stupor. He had been admitted to a regional hospital with a 3-day history of bloody diarrhea, colic abdominal pain and fever. Two days later, he had complained of generalized seizures and oliguria. On admission, he developed anuria, and serum blood nitrogen and creatinine increased to 56 mg/100 ml and 2.8 mg/100 ml, respectively. Platelets decreased to 42,000/microl. Under the diagnosis of HUS, a continuous hemodiafiltration treatment had to be instituted. Computed tomography of his head at hospital day 5 revealed abnormal low density area of infarction with edema in both the basal ganglia involving with the posterior limb of internal capsule. Serum titer of IgM antibody to Escherichia coli O157 showed positive value. Although his anuria and stupor persisted over 10 days, he recovered without serious complications. These clinical observations may indicate that patients with similar lesions do not necessarily have serious morbidity.

Child↗
PubMed2001

Tubulointerstitial nephritis and uveitis syndrome in two siblings.

Two Japanese sisters with persistent uveitis showed significant increased levels of urinary beta-2 microglobulin. A percutaneous renal biopsy performed in the younger sister revealed tubulointerstitial nephritis (TIN) with helper/inducer T cell infiltrates. Also, abnormal 67-gallium accumulation in the kidneys, suggesting TIN, was observed in the other one at the same time. Although patients with the syndrome of tubulointerstitial nephritis and uveitis (TINU) have been reported to date, its occurrence in siblings has rarely been seen. Both of them shared same human leukocyte antigen (HLA) DR6, suggesting the potential association between HLA-DR6 and TINU.

Adolescent↗
PubMed2001

[Childhood t(8;21) acute myelocytic leukemia: a comparison of clinical features and risk factors with adult cases].

Despite the abundance of reports describing adult cases of t(8;21) acute myelocytic leukemia (AML), childhood cases have received little attention. We retrospectively investigated 14 childhood cases of t(8;21) AML, and compared their clinical characteristics with those of adult cases, focusing on the risk factors for poor prognosis. Seventy-one percent of the patients had fever. Their mean leukocyte count was 12,700/microliter, and they showed decreased NAP activity. The cell surface showed positivity for CD13, 33, 19, 34, and HLA-DR. The complete remission rate was 100%, and relapse was observed in three of the patients. Bone marrow eosinophilia was present in a smaller proportion of the childhood cases than in the adult cases. Although an increased leukocyte count, tumor formation, and other risk factors have been reported in adults, there was no correlation between these factors and prognosis in our childhood cases. As children who showed AML relapse had TdT-positive blasts, detectable blast TdT activity may be a risk factor for relapse in childhood cases of t(8;21) AML. However, to confirm this, a study with a larger subject base should be conducted.

Adolescent↗
PubMed2001

Surfactant protein D and KL-6 as serologic indicators of Pneumocystis carinii pneumonia in a child with acute lymphoblastic leukemia.

Pneumocystis carinii pneumonia (PCP) in immunocompromised patients is one of the important causes of morbidity and mortality. Serum levels of surfactant protein D (SP-D) and KL-6 are useful biomarkers for understanding some pulmonary inflammatory responses in patients with idiopathic pulmonary fibrosis (IPF). We present a child with PCP following bone marrow transplantation (BMT) for acute lymphoblastic leukemia (ALL), for whom both SP-D and KL-6 in sera were simultaneously measured through the clinical course of PCP. Both serum levels of SP-D and KL-6 were rapidly elevated reflecting some inflammatory processes in the lung that chest X-ray films and CT scans showed as ground-glass attenuations. He died due to respiratory failure 40 days after PCP developed. A combination of the assays for SP-D and KL-6 in sera may be helpful in predicting the treatment results for PCP.

Adolescent↗