Search PubMed⌕ Search

Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 253 records · Page 14Linked to original sources
PubMed1997

[Umbilical cord blood transplantation for a patient with Diamond-Blackfan syndrome].

A five-year-old girl with Diamond-Blackfan syndrome received cord blood transplantation from an HLA-identical sibling. The patient showed pale face at birth, and was diagnosed to have Diamond-Blackfan syndrome. She had been treated with prednisolone (PSL), high dose of methylprednisolone, erythropoietin, and anti-lymphocyte globulin. Despite of these intensive therapies, erythropoiesis did not entirely improve, and transfusion of red blood cells had been required every third or fourth week until cord blood transplantation. Conditioning regimen consisted of thoraco-abdominal irradiation (TAI; 8 Gy), cyclophosphamide (CY; 50 mg/kg x 4), and anti-thymocyte globulin (ATG; 2.5 mg/kg x 4), Cyclosporin (CyA 3 mg/kg) was administered for the prophylaxis of graft-versus-host disease (GVHD). 4.14 x 10 (7)/kg of cord blood mononuclear cells were infused to the patient. White blood cell (WBC) and reticulocyte counts increased promptly, but recovery of platelet count was delayed. Skin GVHD (grade I) appeared on day +9, which responded to the administration of PSL (2 mg/kg). Chromosomal analyses of bone marrow cells for sex mismatch revealed complete chimerism on day +14, on day +28 and thereafter. Umbilical cord blood cells can be an alternative source of hematopoietic stem cells for allogeneic transplantation.

Child, Preschool↗
PubMed1997

Kinetic assay of serum and urine for urea with use of urease and leucine dehydrogenase.

We describe a new kinetic assay for determining urea in serum or urine with use of urease (EC 3.5.1.5) and leucine dehydrogenase (EC 1.4.1.9). The latter enzyme is suitable for the kinetic assay of NH4+ because its Km value for NH4+ at pH 8.75 is large (approximately 500 mmol/L). Interference from endogenous NH4+ in serum or urine is obviated by subtraction of the assayed endogenous NH4+ value in a sample blank. For serum, within-assay CVs (n = 10) were 0.39-0.58%; day-to-day CVs (n = 10) were 1.56-2.30%. In urine, within-assay CVs (n = 10) were 0.86-1.15%. Analytical recovery of urea (0.893-71.4 mmol/L) added to patients' sera (urea 6.14 mmol/L) was 99.2-105.2%. The calibration curve for serum was linear through zero for urea concentrations up to 142.9 mmol/L and for urine up to 714.3 mmol/L. No influences of added ammonium ion, bilirubin, hemoglobin, ascorbic acid, or Intralipid were observed. The regression equations for this method (y) and conventional methods (x = Determiner-LUN for serum assays, Serotec UUR-R for urine) were: y = 1.016x - 0.12 mmol/L (r = 0.999, S(y/x) = 0.34 mmol/L, n = 100) for sera, and y = 1.070x - 12.6 mmol/L (r = 0.998, S(y/x) = 7.41 mmol/L, n = 100) for urine.

Amino Acid Oxidoreductases↗
PubMed1996

Analysis of interleukin 6 receptor and gp130 expressions and proliferative capability of human CD34+ cells.

We recently demonstrated that stimulation of gp130 by a combination of soluble interleukin 6 receptor (sIL-6R) and IL-6 but not IL-6 alone significantly stimulates the ex vivo expansion of primitive hematopoietic progenitors and the generation of erythroid cells from human CD34+ cells in the presence of stem cell factor (SCF). Here, we show that gp130 is found low positively on most CD34+ cells, whereas IL-6R is expressed on only 30-50% of these cells. Although most of the colonies generated from FACS-sorted CD34+IL-6R+ cells were granulocyte/macrophage (GM) colonies, CD34+IL-6R- cells gave rise to various types of colonies, including erythroid bursts, GM, megakaryocytes, and mixed colonies in methylcellulose culture with a combination of IL-6, sIL-6R, and SCF. Similar results were obtained in culture supplemented with a combination of IL-3, IL-6, SCF, granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin. A limiting dilution analysis of long-term culture-initiating cells (LTC-IC) showed that the CD34+IL-6R- cells contained a larger number of LTC-IC than did the CD34+IL-6R+ cells. In a serum-free suspension of CD34+IL-6R- cells, the addition of sIL-6R to the combination of IL-6 and SCF dramatically increased the total and multipotential progenitors, whereas CD34+IL-6R+ cells failed to do so under the same conditions. These results indicate that most of the erythroid, megakaryocytic, and primitive human hematopoietic progenitors are included in the IL-6R- populations, and the activation of gp130 on these progenitors can be achieved by a complex of IL-6-sIL-6R, but not by IL-6 alone. The present culture system using IL-6, sIL-6R, and SCF may provide a novel approach for ex vivo expansion of human primitive hematopoietic progenitors.

Adult↗
PubMed1996

Selective growth of human mast cells induced by Steel factor, IL-6, and prostaglandin E2 from cord blood mononuclear cells.

To establish the method for generating a large number of mature human mast cells, we cultured cord blood mononuclear cells (CBMC) in several conditions in the presence of Steel factor (SF). Among several cytokines tested, IL-6 enhanced SF-dependent mast cell growth from purified CD34+ cells for more than 8 wk in culture. When CBMC were cultured instead of CD34+ cells, IL-6 enhanced the mast cell development in the presence but not in the absence of PGE2. PGE2 enhanced the SF- and IL-6-dependent development of mast cells from CBMC probably by blocking granulocyte-macrophage CSF (GM-CSF) secretion from accessory cells, because 1) PGE2, or anti-GM-CSF enhanced the mast cell development induced by SF and IL-6 from CBMC, but not from CD34+ cells; 2) GM-CSF inhibited the enhancing effect of IL-6 on the mast cell development from CD34+ cells; and 3) PGE2 inhibited GM-CSF secretion from CBMC. The mast cells cultured in the presence of SF, IL-6, and PGE2 for >10 wk were 99% pure, and seemed to be functionally mature, because 1) they contained 5.62 micrograms of histamine and 3.46 micrograms of tryptase per 10(6) cells; and 2) when sensitized with human IgE and then challenged with anti-human IgE, the cells released a variety of mediators such as histamine, and an increase in intracellular Ca2+ was found in advance of the activation of membrane movement by using a confocal laser-scanning microscope. Electron-microscopic analysis revealed that some of the cultured mast cells are morphologically mature since they filled with scroll granules and contained crystal granules.

Base Sequence↗
PubMed1996

Alterations in basal and glucose-stimulated voltage-dependent Ca2+ channel activities in pancreatic beta cells of non-insulin-dependent diabetes mellitus GK rats.

In genetically occurring non-insulin-dependent diabetes mellitus (NIDDM) model rats (GK rats), the activities of L- and T-type Ca2+ channels in pancreatic beta cells are found to be augmented, by measuring the Ba2+ currents via these channels using whole-cell patch-clamp technique, while the patterns of the current-voltage curves are indistinguishable. The hyper-responsiveness of insulin secretion to nonglucose depolarizing stimuli observed in NIDDM beta cells could be the result, therefore, of increased voltage-dependent Ca2+ channel activity. Perforated patch-clamp recordings reveal that the augmentation of L-type Ca2+ channel activity by glucose is markedly less pronounced in GK beta cells than in control beta cells, while glucose-induced augmentation of T-type Ca2+ channel activity is observed neither in the control nor in the GK beta cells. This lack of glucose-induced augmentation of L-type Ca2+ channel activity in GK beta cells might be causatively related to the selective impairment of glucose-induced insulin secretion in NIDDM beta cells, in conjunction with an insufficient plasma membrane depolarization due to impaired closure of the ATP-sensitive K+ channels caused by the disturbed intracellular glucose metabolism in NIDDM beta cells.

Animals↗
PubMed1996

Chemotactic and chemokinetic activities of stem cell factor on murine hematopoietic progenitor cells.

We investigated the effects of stem cell factor (SCF) on the migration of murine bone marrow hematopoietic progenitor cells (HPC) in vitro using a modification of the checkerboard assay. Chemotactic and chemokinetic activities of SCF on HPC were evaluated by the numbers of HPC migrated on positive and negative gradients of SCF, respectively. On both positive and negative gradients of SCF, HPC began to migrate after 4 hours incubation, and their numbers then increased time-dependently. These results indicated that SCF functions as a chemotactic and chemokinetic agent for HPC. Analysis of types of colonies derived from the migrated HPC showed that SCF had chemotactic and chemokinetic effects on all types of HPC. When migrating activities of other cytokines were examined, interleukin (IL)-3 and IL-11 also affected the migration of HPC, but the degrees of each effect were lower than that of SCF. The results of the present study demonstrated that SCF is one of the most potent chemotactic and chemokinetic factors for HPC and suggest that SCF may play an important role in the flow of HPC into bone marrow where stromal cells constitutively produce SCF.

Animals↗
PubMed1996

32P-Postlabeling analysis of a DNA adduct, an N2-acetyl derivative of guanine, formed in vitro by methylglyoxal and hydrogen peroxide in combination.

Methylglyoxal is a direct-acting mutagen in Salmonella typhimurium TA100 and its mutagenicity is markedly enhanced in the presence of hydrogen peroxide. In addition, a mixture of methylglyoxal and hydrogen peroxide reacts with 2'-deoxyguanosine to form N2-acetyl-2'-deoxyguanosine. We examined whether the guanine residues in DNA were acetylated by methylglyoxal in the presence of hydrogen peroxide using the 32P-postlabeling method. First, N2-acetyl-2'-deoxyguanosine 3'-monophosphate and N2-acetyl-2'-deoxyguanosine 3,5'-diphosphate were chemically synthesized as standard compounds for the analysis. Then calf thymus DNA (3.24 micromol) was treated with methylglyoxal (64.8 micromol) at pH 7.4 for 3 h at 37 degrees C, and subsequently with hydrogen peroxide (64.8 micromol) at 37 degrees C for 2 h. The adduct formation was analyzed using HPLC in combination with the 32P-postlabeling method under the standard conditions. N2-Acetyl-2'-deoxyguanosine was detected at levels of 2/10(6) nucleotides in double-stranded DNA and 1/10(5) nucleotides in single-stranded DNA. The estimated limit of detection by our method was 3 per 10(8) nucleotides.

Acetylation↗
PubMed1996

Erythropoietin-independent erythrocyte production: signals through gp130 and c-kit dramatically promote erythropoiesis from human CD34+ cells.

Erythropoietin (EPO) is the primary humoral regulator of erythropoiesis and no other factor has previously been reported to support proliferation and terminal maturation of erythroid cells from hemopoietic stem cells. Here we show that stimulation of glycoprotein (gp130) by a combination of recombinant human soluble interleukin 6 receptor (sIL-6R) and IL-6 but not sIL-6R or IL-6 alone can support proliferation, differentiation, and terminal maturation of erythroid cells in the absence of EPO from purified human CD34+ cells in suspension culture containing stem cell factor (SCF). A number of erythroid bursts and mixed erythroid colonies also developed in methylcellulose culture under the same combination. The addition of anti-gp130 monoclonal antibodies but not anti-EPO antibody to the same culture completely abrogated the generation of erythroid cells. These results clearly demonstrate that mature erythroid cells can be emerged from hemopoietic progenitors without EPO in vitro. Together with the previous reports that human sera contain detectable levels of sIL-6R, IL-6, and SCF, current data suggest that gp130 signaling in association with c-kit activation may play a role in human erythropoiesis in vivo.

Antigens, CD↗
PubMed1996

Stable clonal expansion of T cells induced by bone marrow transplantation.

The immune mechanisms of T cells regeneration after bone marrow transplantation (BMT) and the factors maintaining allogeneic marrow graft in the host are still unknown. To pursue this issue, we analyzed T-cell clonality of peripheral blood lymphocytes (PBLs) in BMT recipients, using reverse transcription polymerase chain reaction with T-cell receptor (TCR) V beta gene segment-specific primers and single-strand conformation polymorphism. PBLs from patients and donors showed a heterogeneous T-cell population with oligoclonal accumulations of CD8+ T cells. When PBLs were cultured in HLA-matched mixed lymphocytes reaction in vitro, no distinct clonal expansion was observed. However, after BMT, oligoclonal expansions were induced in the recipients in vivo, without a restriction of TCR V beta gene usage. Although part of the expansion was transient, the majority was repeatedly detected even several months later. Our results suggested that certain in vivo mechanisms maintain a stable clonal expansion of distinct T cells in marrow recipients. We also found in a single patient with graft-versus-host disease a replacement of expanded clones by other clones during follow-up. Diminishing numbers of accumulation clones were found in long-term marrow recipients, indicating a general tendency for clonal expansion to subside progressively. Considered together, our data suggest the involvement of clonally expanded T cells in lymphoid regeneration and in acute and chronic immune responses after BMT.

Adolescent↗
PubMed1996

Microcystin levels during 1992-95 for Lakes Sagami and Tsukui-Japan.

Toxic cyanobacterial blooms have been frequently observed in Lakes Sagami and Tsukui, Kanagawa Prefecture, Japan, which are used as drinking and recreational water sources. As the first step toward the control and removal of cyanobacterial toxins, the present study evaluated the microcystin level in these lakes. Our established method using HPLC and LC/MS to pursue trace amounts of microcystins was applied to the determination of microcystins within cyanobacteria cells and in water. We could determine precisely the intracellular and extracellular microcystin level in the water environment during 1992-95. Microcystins RR, LR, and YR were detected at 0.02-2.64 micrograms/L in cell-free water and at 0.02-378 micrograms/L in the cells. Although there were many cases in which microcystin concentrations in the cells exceeded the proposed guideline level (1 microgram/L), there was only one example of this happening in cell-free water samples. Because the present monitoring indicated that the amount of microcystins detected in water was much less than that estimated in cells, the release of microcystins from the cells and their stability in lake water were examined in the dark. The resulting toxins persisted at the same concentration level for 14 days and the microcystin concentrations steadily declined, showing that biodegradation using aquatic natural bacterial flora is an effective detoxification process under natural conditions.

Biodegradation, Environmental↗
PubMed1996

The coexistence of systemic sclerosis and rheumatoid arthritis in five patients. Clinical and immunogenetic features suggest a distinct entity.

To elucidate the clinical characteristics and pathogenesis of scleroderma-rheumatoid arthritis (SSc-RA) overlap syndrome, we analyzed the clinical features of 5 patients with SSc-RA overlap. Their HLA phenotypes and genotypes were also determined. Generalized skin sclerosis, severe seropositive polyarthritis, pulmonary fibrosis, anti-topoisomerase I antibodies, and HLA-DR4,53;DQA1*0301;DBQ1*04 haplotype were observed in all of the patients. Similar clinical features were recognized in most of the 10 cases reported previously. Our case studies indicate that SSc-RA overlap may be a distinct entity.

Aged↗
PubMed1996

Role of aspartate in ischemic spinal cord damage.

To study the potentially different roles of the excitatory amino acids glutamate and aspartate in the development of ischemic injury of the spinal cord, we measured their release from cultured neurons and glial cells under ischemic conditions. We also examined changes in intracellular Ca2+ concentration and the damage elicited in cultured neurons by glutamate and aspartate. Hypoxic-hypoglycemic treatment (in vitro ischemia) elicited a rapid release of the excitatory amino acids from cultured spinal cord neurons and glial cells, but the release was greater from glial cells than from neurons. The ischemia-induced glutamate release from glial cells was transient; the aspartate release lasted longer, although the peak level was smaller than that of glutamate. In cultured neurons, a remarkable elevation in intracellular Ca2+ concentration was induced by glutamate but not by a lower concentration (10 microM) of aspartate, which is below the neurotoxic dose. At the higher concentration (100 microM), both excitatory amino acids induced a marked elevation in intracellular Ca2+ concentration and neuronal death. These results indicate that aspartate is less potent than glutamate in eliciting excitatory neurotransmission under normal physiological conditions. However, under pathological conditions such as ischemia, the increased release of aspartate from glial cells may add to the damage to neighboring neurons.

Animals↗
PubMed1996

HLA antigens are candidate markers for prediction of lymph node metastasis in gastric cancer.

We investigated the association between human leucocyte antigen (HLA) antigens and lymph node metastasis in 724 gastric cancer patients. Among patients who had poorly differentiated adenocarcinoma with or without HLA-DR4 antigen, lymph node metastasis was detected in 80.8 and 54.9%, respectively (relative risk (RR) = 3.5, P = 0.0005, corrected P = 0.0285). It was more common in patients with a family history of cancer death (RR = 7.7). Among signet ring cell carcinoma patients with or without HLA-B52 antigen, lymph node metastasis was detected in 57.7 and 19.7%, respectively (RR = 5.6, P = 0.0001, corrected P = 0.0086). It was more common in patients who were smokers (RR= 8.3). Our findings suggest that HLA-DR4 and HLA-B52 antigens are associated with lymph node metastasis in gastric cancer.

Adult↗
PubMed1996

Role of glycoprotein 130 and c-Kit signaling in proliferation and differentiation of human hematopoietic progenitor cells.

Glycoprotein (gp) 130, a receptor component for interleukin 6 (IL-6), can associate with a soluble IL-6 receptor (sIL-6R)-IL-6 complex. To examine the role of gp130 signaling in human hematopoietic progenitor-cell proliferation and differentiation, we studied the effects of the sIL-6R-IL-6 complex in combination with other cytokines on human CD34+ cells in clonal and suspension cultures. The sIL-6R-IL-6 complex, but not sIL-6R or IL-6 alone, in the presence of stem-cell factor (SCF) produced dramatic increases in the populations of various cell lineages, including erythroid cells and various hematopoietic progenitors, in suspension culture. Significant numbers of colonies of (particularly) multilineage and blast cells were generated in methylcellulose culture supplemented with a combination of sIL-6R-IL-6 complex and SCF. Addition of anti-gp130 monoclonal antibodies (MAbs) and anti-IL-6R MAbs to the above-mentioned cultures dose-dependently inhibited the generation of cells of various lineages and of progenitor cells in suspension culture and completely blocked multilineage colony production in methylcellulose culture; an anti-erythropoietin antibody did not cause inhibition. These findings demonstrate that both proliferation and differentiation of hematopoietic progenitor cells can be induced through gp130 and c-Kit signaling, indicating that progenitor cells are responsive to the sIL-6R-IL-6 complex, even though they do not express IL-6R. Together with previous studies showing that detectable levels of sIL-6R, IL-6, and SCF are present in human serum, these results suggest that gp130 signaling may play an important role in human hematopoiesis in vivo.

Antigens, CD34↗
PubMed1996

Study on neurotoxic shellfish poisoning involving the oyster, Crassostrea gigas, in New Zealand.

Lipid-soluble polyether marine toxins were isolated from 80% methanol extract of oysters, Crassostrea gigas, harvested in 1993 at Tiki Road, Coromandel Peninsula, New Zealand, by chromatography on columns of LH-20 and ODS (C18), followed by reversed-phase high-performance liquid chromatography. They were identified as known brevetoxins, PbTx-2 and 3. PbTx-3 was also isolated from oysters collected at Rangaunu Harbour in February 1994 and June 1995, followed by the above procedures.

Animals↗
PubMed1996

Security implementation issues in Japan.

A survey was conducted in the year 1994 among medical school hospitals in Japan to know whether there are some written rules or regulations about the use of medical information, and whether they are well matched both to secure patient's privacy and to promote the adequate use of the information. A questionnaire was mailed to 80 medical school hospitals in Japan and 65 of them responded. Besides copies of rules, questioners were also requested for detailed investigation. Twenty nine hospitals responded to our request. The security implementation issues in Japan will be discussed using data thus obtained.

Computer Security↗