PubMed Health⌕ Search

Biomedical subjects

H Ema

Publications and source records attributed to H Ema.

At least 19 recordsLinked to original sources
PubMed2006

Effect of different dialyzer membranes on cutaneous microcirculation during hemodialysis.

AIM: Biocompatibility profiles of synthetic membranes may vary. In this prospective crossover study, we examined the effect of various membranes on cutaneous microcirculation during HD. SUBJECTS AND METHODS: 11 HD patients without cardiovascular complications were enrolled in this study. They were dialyzed using three types of membrane in a randomized order: ethylene-vinyl alcohol copolymer (EVAL), vitamin E-bonded cellulose (VE-C) and polysulfone (PS). The transcutaneous oxygen tension (TcPO2) was examined on the dorsum of foot to assess the cutaneous microcirculation. Serum biochemical parameters were also measured. RESULTS: The TcPO2 as a percentage of the predialysis level decreased from the beginning of HD, and significant differences were observed after 15 min of HD between EVAL and the other 2 membranes (98 +/- 6% (mean +/- SD) for EVAL versus 89 +/- 7% for VE-C (p < 0.01) and 88 +/- 10% for PS (p < 0.01)). Furthermore, there were significant differences at 30 and 60 min between EVAL and PS (30 min: 93 +/- 9% for EVAL versus 85 +/- 7% for PS (p < 0.05); 60 min: 92 +/- 10% for EVAL versus 79 +/- 10% for PS (p < 0.01)). The serum level of thiobarbituric acid reactants (TBARs), a marker of lipid peroxidation, increased significantly at the end of HD relative to that at the beginning of HD when using a PS membrane (from 1.9 +/- 0.5 to 2.1 +/- 0.5 nmol/ml, p < 0.05). CONCLUSION: Our results indicate that an EVAL membrane is superior to PS and VE-C membranes in terms of its smaller influence on cutaneous microcirculation. The repeated occurrence of microcirculatory disturbance during HD sessions may cause chronic endothelial dysfunction and even cardiovascular complications in HD patients.

Adult↗
PubMed2001

Quantitative assessment of the stem cell self-renewal capacity.

Little is known about the manner in which hematopoietic stem cells (HSCs) self-renew. To address this issue, we used a serum-free single-cell culture, followed by transplantation of cultured cells into lethally irradiated mice. CD34-negative or low, c-Kit-positive, Sca-1-positive, lineage marker-negative (CD34-KSL) cells are highly enriched for murine bone marrow HSCs. Successful long-term reconstitution with a single CD34-KSL cell enabled us to study in vitro self-renewal of HSC at clonal level. Using this clonal cell transplantation system, we examined the effect of various cytokines on CD34-KSL cells. Among the cytokines examined, stem cell factor (SCF) and thrombopoietin (TPO) were minimum cytokines to induce cell division of CD34-KSL cells most efficiently. Similarly, multilineage repopulating activity was detected in the cells derived from a significant portion of single cells after culture in the presence of TPO and SCF. However, SCF + IL-3, SCF + IL-6, or SCF + IL-11 + FL appeared to be less effective for self-renewal of HSCs. The activity of HSCs as indicated by repopulation unit (RU) remaining after culture with SCF and TPO was not so different from that of freshly isolated HSCs. However, there was a substantial loss of HSC number in these cultured cells. Taken together, this study provides definitive proof that one HSC can generate at least one HSC in vitro.

Animals↗
PubMed2000

Hematopoietic stem cells express Tie-2 receptor in the murine fetal liver.

Tie-2 receptor tyrosine kinase expressed in endothelial and hematopoietic cells is believed to play a role in both angiogenesis and hematopoiesis during development of the mouse embryo. This article addressed whether Tie-2 is expressed on fetal liver hematopoietic stem cells (HSCs) at day 14 of gestation. With the use of anti-Tie-2 monoclonal antibody, its expression was detected in approximately 7% of an HSC population of Kit-positive, Sca-1-positive, lineage-negative or -low, and AA4.1-positive (KSLA) cells. These Tie-2-positive KSLA (T(+) KSLA) cells represent 0.01% to 0.02% of fetal liver cells. In vitro colony and in vivo competitive repopulation assays were performed for T(+) KSLA cells and Tie-2-negative KSLA (T(-) KSLA) cells. In the presence of stem cell factor, interleukin-3, and erythropoietin, 80% of T(+) KSLA cells formed colonies in vitro, compared with 40% of T(-) KSLA cells. Long-term multilineage repopulating cells were detected in T(+) KSLA cells, but not in T(-) KSLA cells. An in vivo limiting dilution analysis revealed that at least 1 of 8 T(+) KSLA cells were such repopulating cells. The successful secondary transplantation initiated with a limited number of T(+) KSLA cells suggests that these cells have self-renewal potential. In addition, engraftment of T(+) KSLA cells in conditioned newborn mice indicates that these HSCs can be adapted equally by the adult and newborn hematopoietic environments. The data suggest that T(+) KSLA cells represent HSCs in the murine fetal liver. (Blood. 2000;96:3757-3762)

Animals↗
PubMed2000

Age-associated characteristics of murine hematopoietic stem cells.

Little is known of age-associated functional changes in hematopoietic stem cells (HSCs). We studied aging HSCs at the clonal level by isolating CD34(-/low)c-Kit(+)Sca-1(+) lineage marker-negative (CD34(-)KSL) cells from the bone marrow of C57BL/6 mice. A population of CD34(-)KSL cells gradually expanded as age increased. Regardless of age, these cells formed in vitro colonies with stem cell factor and interleukin (IL)-3 but not with IL-3 alone. They did not form day 12 colony-forming unit (CFU)-S, indicating that they are primitive cells with myeloid differentiation potential. An in vivo limiting dilution assay revealed that numbers of multilineage repopulating cells increased twofold from 2 to 18 mo of age within a population of CD34(-)KSL cells as well as among unseparated bone marrow cells. In addition, we detected another compartment of repopulating cells, which differed from HSCs, among CD34(-)KSL cells of 18-mo-old mice. These repopulating cells showed less differentiation potential toward lymphoid cells but retained self-renewal potential, as suggested by secondary transplantation. We propose that HSCs gradually accumulate with age, accompanied by cells with less lymphoid differentiation potential, as a result of repeated self-renewal of HSCs.

Aging↗
PubMed2000

In vitro self-renewal division of hematopoietic stem cells.

Little is known about how hematopoietic stem cells (HSCs) self-renew. We studied the regeneration of HSCs in culture. Effects of various cytokines on cell division of CD34(-/low) c-Kit(+)Sca-1(+) lineage marker-negative (CD34(-)KSL) bone marrow cells of the mouse were first evaluated in serum-free single cell culture. We then performed a competitive repopulation assay on divided cells to ask if such cell division involved self-renewal of HSCs. In the presence of stem cell factor (SCF), thrombopoietin (TPO) induced a first cell division of CD34(-)KSL cells more efficiently than did interleukin (IL)-3 or IL-6. Multilineage repopulating cells were detected in a significant proportion of cells derived from single cells in culture with TPO and SCF, although this culture condition led to a substantial decrease in HSC number. These regenerated repopulating cells could be further transplanted into secondary recipients. When paired daughter cells were separately studied, one of a pair gave rise to repopulating cells with self-renewal potential, suggesting asymmetric self-renewal division. This study provides evidence that one HSC regenerates at least one HSC in culture.

Animals↗
PubMed2000

Expansion of hematopoietic stem cells in the developing liver of a mouse embryo.

The activity of hematopoietic stem cells in the developing liver of a C57BL/6 mouse embryo was quantified by a competitive repopulation assay. Different doses of fetal liver cells at days 11 to 18 of gestation were transplanted into irradiated mice together with 2 x 10(5) adult bone marrow cells. A long-term repopulation in myeloid-, B-cell, and T-cell lineage by fetal liver cells was evaluated at 20 weeks after transplantation. At day 12 of gestation multilineage repopulating activity was first detected in the liver as 50 repopulating units (RU) per liver. The number of RU per liver increased 10-fold and 33-fold by day 14 and day 16 of gestation, and decreased thereafter, suggesting a single wave of stem cell development in the fetal liver. A limiting dilution analysis revealed that the frequency of competitive repopulating units (CRU) in fetal liver cells at day 12 of gestation was similar to that at day 16 of gestation. Because of an increase of total fetal liver cell number, the absolute number of CRU per liver from days 12 to 16 of gestation increased 38-fold. Hence, the mean activity of stem cells (MAS) that is given by RU per CRU remained constant from days 12 to 16 of gestation. From these data we conclude that hematopoietic stem cells expand in the fetal liver maintaining their level of repopulating potential.

Animals↗
PubMed2000

Dominant expansion of human T cells in non-obese diabetic/severe combined immunodeficiency mice implanted with human bone fragments.

OBJECTIVE: To establish an in vivo animal model in which human T cells develop and function normally, a step toward developing new vaccines or chemical compounds that modulate immune functions and toward understanding T-cell immunity in humans. MATERIALS AND METHODS: Human bone fragments were implanted into non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice. The presence of human blood cells in the peripheral blood of these mice was monitored periodically by immunostaining and fluorescence-activated cell sorting. RESULTS: After implantation of bone fragments, dominant expansion of human T lymphocytes, rather than myeloid and B cells, was observed over a 3-month period. In some cases, the proportion of human T cells rose to 40% of the peripheral blood mononuclear cells. These T cells showed CD4/CD8 ratios similar to those observed in human peripheral blood lymphocytes and had a broad repertoire of rearranged T-cell receptor genes. Graft-versus-host reaction was not noted in any organ analyzed. To assess the suitability of NOD/SCID mice implanted with human bone fragments (hu-bone-NOD/SCID mice) as an in vivo model for HIV infection, the mice were infected with a T-lymphotropic strain of HIV-1 (NL4-3) at 7 weeks posttransplant. Serum p24 gag was detected at 2 weeks after inoculation, after which total CD4-positive cell numbers declined, as seen clinically in patients infected with HIV. CONCLUSION: Although the precise mechanism is yet to be determined by which predominant expansion of human T cells occurs in hu-bone-NOD/SCID mice, such mice appear likely to serve as a useful and versatile model for studies involving human T-cell immunity.

Animals↗
PubMed1999

Further characterization of CD34-low/negative mouse hematopoietic stem cells.

We have previously reported that in adult mouse bone marrow, CD34low/- c-kit+ Sca-1+ lineage markers negative (Lin-) (CD34-KSL) cells represent hematopoietic stem cells with long-term marrow repopulating ability whereas CD34+ c-kit+ Sca-1+ Lin- (CD34+KSL) cells are progenitors with short-term reconstitution capacity. To further characterize cells in those two populations, relative expression of various genes were examined by reverse transcriptase polymerase chain reaction (RT-PCR). In CD34-KSL cells, none of the genes studied was found to be expressed with the exception of GATA-2, IL-1R alpha, IL-2R gamma, AIC-2B, c-kit, EPO-R, and c-mpl. In contrast, expression of GATA-1 and all cytokine receptor genes examined except IL-2R beta, IL-7R alpha and IL-9R alpha were found in CD34+KSL. The difference between these two populations was also shown in single cell culture analysis of these cells. When cells were clone-sorted and cultured in the presence of SCF, IL-3 and EPO, CD34-KSL cells required much more time to undergo the first cell division than CD34+KSL cells. Dormancy and random fashion of cell division by CD34-KSL cells were also evident by the analysis of the second cell division, which was found to be delayed and unsynchronous compared with CD34+KSL cells. Clonal culture analysis showed that CD34-KSL cells were more potent in proliferation and multilineage differentiation capacities than CD34+KSL cells. In a paired-daughter cell experiment, 75% of CD34-KSL and 50% of CD34+KSL paired-daughter-derived colonies were nonidentical with wide variety of lineage combinations. Taken together, these data support our previous notion that CD34-KSL cells are at higher rank in hematopoietic hierarchy than CD34+KSL cells. In addition, our results using highly enriched stem cell population directly obtained from mouse bone marrow support the proposed stochastic nature of lineage commitment.

Animals↗
PubMed1999

Comparison of hematopoietic activities of human bone marrow and umbilical cord blood CD34 positive and negative cells.

Although the hematopoietic activities of human CD34+ bone marrow (BM) and cord blood (CB) cells have been well characterized, the phenotype of nonobese-diabetic severe combined immunodeficient (NOD/SCID) mice repopulating cells (SRCs) in CB and BM has not yet been fully examined. To address this issue, various hematopoietic activities were compared in terms of total and CD34+ CB and BM cells. Clonal culture of fluorescence-activated cell sorter (FACS) CD34+ CB and BM cells revealed a higher incidence of colony-forming cells with greater proliferation capacity in CB over BM CD34+ cells. CB CD34+ cells also demonstrated higher secondary plating efficiency over BM cells. In addition, we demonstrated that mice transplanted with CB mononuclear cells (MNCs) showed significantly higher levels of chimerism than those transplanted with BM MNCs. However, recipients of FACS-sorted CD34+ CB cells showed significantly lower levels of chimerism than those that received total CB MNCs, suggesting a role of facilitating cells in the CD34- cell population. To further analyze the role of CD34- cells, the NOD/SCID repopulating ability of FACS-sorted CB CD34-c-kit+Lin- and CD34-c-kit-Lin- cells were examined. However, SRCs were not detected in those cells. Taken together, these data suggest that CB is a better source of hematopoietic stem cells and that there are cells in the CD34- fraction that facilitate repopulation of hematopoiesis in the NOD/SCID environment.

Animals↗
PubMed1998

Development of T cell precursor activity in the murine fetal liver.

The generation of T cell precursors in the liver of murine embryos was studied. The total number of T cell precursors in the liver was measured in thymic organ cultures by a limiting dilution assay. Sixty T cell precursors were detected in the liver at day 11 of gestation. By day 12 the number of precursors showed a 20-fold increase, half of which could be explained by in situ proliferation as ascertained by a fetal liver organ culture assay. By day 13 a further 2-3-fold increase was observed. Whereas the number of total liver cells continued to increase, that of T cell precursors declined in the following days, suggesting a massive exit of these cells after day 13. The capacity to generate a TCRB repertoire in the cells was evaluated by a PCR assay. T cell precursors in day 11 fetal liver developed a TCRB repertoire at day 8 of culture. The cells from days 12-15 developed an identically diverse repertoire by day 6, suggesting that day 11 precursors are more immature than those of later days. A mechanism for yielding a single wave of T cell precursors in the fetal liver is discussed with a proposed model.

Animals↗
PubMed1997

TCR-beta repertoire development in the mouse embryo.

We studied the TCR beta-chain repertoire in thymocytes along embryonic development. At day 14 of gestation, complete V-D-J rearrangements of the TCR-beta locus were detected at the messenger RNA level, and a total of 56 different rearrangements were observed in one thymus. At this stage, thymocytes showed preferential usage of TCR-betaV1, TCR-betaV2, and TCR-betaV8 together with TCR-betaJ1S1, -J1S2, and -J2S7 segments. This frequent usage of V and J segments was similar to the usage seen in the adult thymus. Assuming that day 14 thymocytes were not subjected to specificity selection, we conclude that the expression of TCR-betaV and J segments is biased from the beginning of T cell repertoire creation. The first detectable transcripts of rearranged TCR-betas were different among individual fetuses and constituted a random representation of the ones seen at later stages of thymic ontogeny. The diversity of TCR-beta rearrangements increased with time and became indistinguishable from that of the adult by day 16. The first rearranged TCR-alphas were expressed at day 17 and their diversity increased thereafter. We conclude that the diversification of the beta-chain repertoire takes place in 3 days, before the alpha-chain rearrangement begins in transition from CD4/CD8 double negative to double positive cells.

Animals↗
PubMed1997

In vitro maintenance of highly purified, transplantable hematopoietic stem cells.

The cellular and molecular mechanisms that regulate the most primitive hematopoietic stem cell are not well understood. We have undertaken a systematic dissection of the complex hematopoietic microenvironment to define some of these mechanisms. An extensive panel of immortalized stromal cell lines from murine fetal liver were established and characterized. Collectively, these cell lines display extensive heterogeneity in their in vitro hematopoietic supportive capacity. In the current studies, we describe a long-term in vitro culture system using a single stromal cell clone (AFT024) that qualitatively and quantitatively supports transplantable stem cell activity present in highly purified populations. We show multilineage reconstitution in mice that received the equivalent of as few as 100 purified bone marrow and fetal liver stem cells cultured for 4 to 7 weeks on AFT024. The cultured stem cells meet all functional criteria currently ascribed to the most primitive stem cell population. The levels of stem cell activity present after 5 weeks of coculture with AFT024 far exceed those present in short-term cytokine-supported cultures. In addition, maintenance of input levels of transplantable stem cell activity is accompanied by expansion of other classes of stem/progenitor cells. This suggests that the stem/progenitor cell population is actively proliferating in culture and that the AFT024 cell line provides a milieu that stimulates progenitor cell proliferation while maintaining in vivo repopulating activity.

Adipose Tissue↗
PubMed1992

Reactivity profiles of leukemic myeloblasts with monoclonal antibodies directed to sialosyl-Le(x) and other lacto-series type 2 chain antigens:absence of reactivity with normal hematopoietic progenitor cells.

We investigated the expression profiles of lacto-series type 2 antigens in hematopoietic cells and their progenitors, in comparison with leukemic leukocytes. Reactivity profiles of various anti-type 2 chain monoclonal antibodies (MoAbs) with leukemic blasts from 12 patients with acute myeloblastic leukemia (AML) and those from two patients with acute unclassified leukemia (AUL) show that anti-sialosyl-Le(x) MoAb SNH3 reacted strongly with greater than 95% of leukemic blast leukocyte populations from all patients (14 of 14). Another anti-sialosyl-Le(x) MoAb, FH6, showed less reactivity than SNH3 (12 of 14 patients), while anti-Le(y) MoAb AH6 showed reactivity with only 8 of 14 patients. On the other hand, none of the anti-type 2 chain MoAbs reacted with CD34+ normal adult bone marrow (BM) mononuclear cells obtained independently from three healthy volunteers. MoAb SNH3, but not FH6 or AH6, showed complement-mediated cytotoxicity to leukemic blasts from these patients, as well as to myelogenous leukemia cell line HL60. Colony-forming unit granulocyte-macrophage (CFU-GM), but not burst-forming unit-erythroid (BFU-E), was incompletely inhibited by treatment of normal BM mononuclear cells with SNH3 and complement. The absence of type 2 chain antigen expression in hematopoietic progenitor cells and in in vitro hematopoietic colonies (CFU-GM and BFU-E) strongly suggests that application of anti-carbohydrate MoAbs, particularly anti-sialosyl-Le(x) could be useful for elimination of leukemic myeloblasts infiltrating in BM, for purging of leukemic blasts in BM, and for facilitation of autologous BM transplantation.

Antibodies, Monoclonal↗
PubMed1992

[Acute undifferentiated leukemia from the viewpoints of diagnosis and therapy].

Myeloperoxidase (MPO)- and Sudan Black B-not more than 3%-positive, esterase staining-negative, lymphoid, megakaryocyte lineage and erythroid surface marker-negative and electron microscopic platelet peroxidase-negative acute leukemia (AL) was diagnosed as acute undifferentiated leukemia (AUL), and myeloid marker (CD13, CD33), electron microscopic MPO (EMMPO), and DNA analysis of immunoglobulin heavy chain and T cell receptor as well as chemotherapy and its reactivity were examined. Of 239 cases of AL, 10 (4.2%) were AUL, and of these 10 cases, 9 were CD13 or CD33-positive AML-MO (MO) cases. Of 9 cases examined for EMMPO, 4 (44%) were positive, and of 3 cases of MO subjected to DNA analysis, 1 and 1 showed rearrangements of immunoglobulin heavy chain and T cell receptor beta chain, respectively. Of 6 cases of MO on myeloid induction therapy, 1 and 1 showed complete remission (CR) and partial remission (PR), respectively, each having lymphoid genotype, and 4 showed no remission (NR), being 3 of them EMMPO-positive. Of 2 cases on lymphoid induction therapy, 1 and 1 showed CR and NR, respectively, the former being EMMPO-positive MO. BHAC-EM therapy with behenoyl cytosine arabinoside, VP-16 and mitoxantrone performed on 2 cases refractory to any one of both these myeloid and lymphoid induction therapies led to CR in all these 2 cases.

Adolescent↗
PubMed1991

Multipotent and committed CD34+ cells in bone marrow transplantation.

In order to study the role of CD34+ cells in hematological recovery following bone marrow transplantation (BMT), bone marrow cells stained with HPCA-1 (CD34) and MY-9 (CD33) monoclonal antibodies were analyzed by using a fluorescence-activated cell sorter on or about days 14 and 28, as well as at later times, following BMT in 6 recipients. Single cell cultures of CD34+ cells were also performed to evaluate their in vitro hematopoietic function. CD34+ cells were detectable in bone marrow cells on day 14. More than 80% of CD34+ cells co-expressed the CD33 antigen, and macrophage (Mac) colony-forming cells predominated among total colony-forming cells of CD34+ cells. In normal bone marrow cells, CD34+, CD33+ cells amounted to about 40% of CD34+ cells, and the incidences of erythroid bursts, granulocyte/macrophage (GM) colonies, and Mac colonies were similar to each other. After more than 10 weeks, CD34+, CD33- cells gradually recovered, as erythroid burst colony-forming cells increased following GM colony-forming cells. This phenomenon was well-correlated with the time course of peripheral blood cell recovery. CD34+, CD33+ cells as committed progenitors and CD34+, CD33- cells as multipotent stem cells have distinctive biological behaviors in BMT.

Antibodies, Monoclonal↗
PubMed1991

[Staphylococcus aureus sepsis in patients with hematological malignancies: increase in MRSA sepsis].

From January 1978 to August 1990, Staphylococcus aureus bacteremia (SAB) were identified in 31 patients with hematological malignancies at Jichi Medical School hospital. Mortality due to SAB was 48.4% (15/31). Of the variables analyzed, four factors were significantly associated with a poor prognosis; elderly age (p = 0.015), high granulocyte count (more than 500/microliters) (p = 0.015), presence of DIC (p = 0.011) and presence of pneumonia (p = 0.023). The incidence of methicillin-resistant SAB was 32.3% (10/31) and the first patient developed in 1985. Although not statistically significant, there was a trend of higher mortality for methicillin-resistant SAB (70%) than for methicillin-sensitive SAB (38.1%). Most strains of methicillin-resistant Staphylococcus aureus were sensitive to minocycline, chloramphenicol and vancomycin.

Adult↗
PubMed1990

Target cells for granulocyte colony-stimulating factor, interleukin-3, and interleukin-5 in differentiation pathways of neutrophils and eosinophils.

To study the relationship between hematopoietic factors and their responsive hematopoietic progenitors in the differentiation process, both purified factors and enriched progenitors are required. We isolated total CD34+ cells, CD34+,CD33+ cells, and CD34+,CD33- cells individually from normal human bone marrow cells by fluorescence-activated cell sorter (FACS), and examined the effects of granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), and IL-5 on in vitro colony formation of these cells. CD34+,CD33+ cells formed granulocyte colonies in the presence of G-CSF. Both CD34+,CD33+ cells and CD34+,CD33- cells formed granulocyte/macrophage colonies in the presence of IL-3. Eosinophil (Eo) colonies were only formed by CD34+,CD33- cells in response to IL-3, but scarcely formed by CD34+ cells in the presence of IL-5. We performed the two-step cultures consisting of the primary liquid culture for 6 days and the secondary methylcellulose culture, and serially examined changes in phenotypes of ,he cells cultured in the primary culture. CD34-,CD33+ cells derived from CD34+,CD33+ cells by preincubation with G-CSF or IL-3 formed Eo colonies in the presence of IL-5 but not IL-3. CD34-,CD33+ cells derived from CD34+,CD33- cells by preincubation with IL-3 also formed Eo colonies by support of IL-5 as well as IL-3. Both CD34+ cells gradually lost the CD34 antigen by day 6 of incubation with G-CSF or IL-3. Loss of this antigen was well-correlated with acquisition of susceptibility to IL-5. It was concluded that G-CSF supported the neutrophil differentiation of committed colony-forming cells, IL-3 supported that of both committed and multipotent colony-forming cells. G-CSF and IL-3 also supported the early stage of E. differentiation; IL-5 supported the late stage of that.

Antigens, CD34↗