Search PubMed⌕ Search

Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 559 records · Page 31Linked to original sources
PubMed1996

Granulocyte-colony stimulating factor and stem cell factor are the crucial factors in long-term culture of human primitive hematopoietic cells supported by a murine stromal cell line.

The findings that murine marrow stromal cell line MS-5 supported the proliferation of human lineage-negative (Lin-) CD34+CD38- bone marrow cells in long-term culture have been reported. In this study, we analyzed this proliferating activity of MS-5-conditioned medium (CM) on human primitive hematopoietic cells. When Lin-CD34+CD38- cells of normal human cord blood cells were co-cultured with MS-5, colony forming cells (CFCs) were maintained over 7 weeks in vitro. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using membrane filter (0.45 micron) was negligible for this activity. This indicated that the activity of MS-5 on human primitive hematopoietic cells is a soluble factor(s) secreted from MS-5, which is not induced by the contact between MS-5 and Lin-CD34+CD38- cells. We tried to purify this soluble activity. An active material with a molecular weight of about 150 kDa, determined by gel filtration chromatography, solely supported the growth of Lin-CD34+CD38- cells and Mo7e, a human megakaryocytic cell line. This activity not only reacted with anti-mouse stem cell factor (mSCF) antibody on Western blots, but it was also neutralized in the presence of anti-mSCF antibody. Another active material with a molecular weight of about 20-30 kDa synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed to do so alone, although this synergy was inhibited in the presence of soluble mouse granulocyte-colony stimulating factor (mG-CSF) receptor, which is a chimeric protein consisting of the extracellular domain of mG-CSF receptor and the Fe region of human IgG1. In addition, the latter molecule supported the growth of the G-CSF dependent cell line FD/GR3, which is a murine myeloid leukemia cell line, FDC-P2, transfected with mG-CSF receptor cDNA. Adding of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-CM. Recombinant (r) mSCF and rmG-CSF had synergistic activity on the growth of Lin-CD34+CD38- cells. These results indicated that the activity on Lin-CD34+CD38- cells included in MS-5-CM is based upon the synergistic effects of mSCF and mG-CSF.

ADP-ribosyl Cyclase↗
PubMed1996

Identification of multiple HIV-1 cytotoxic T-cell epitopes presented by human leukocyte antigen B35 molecules.

OBJECTIVE: To identify HIV-1 cytotoxic T lymphocyte (CTL) epitopes presented by human leukocyte antigen (HLA)-B35 molecules that are associated with the accelerated progression of AIDS using a reverse immunogenetic approach. METHODS: 8-mer to 11-mer sequences carrying two anchor residues at position 2 and the carboxy-terminus were selected from HIV-1SF2 strain. Sixty-four peptides matched to these sequences were synthesized and tested by a peptide binding assay using RMA-S-B*3501 cells. Peripheral blood lymphocytes (PBL) from two HIV-1-infected donors carrying HLA-B35 were stimulated once-weekly with each HLA-B*3501 binding peptide. The CTL activity of the cultured cells for the HLA-B35-positive target cells loaded with the corresponding peptides was examined after the second and fourth stimulation. Furthermore, the CTL activity of the cultured cells possessing HLA-B*3501-restricted HIV-1 peptide-specific CTL activity were examined for the HLA-B*3501-positive target cells infected with the recombinant vaccinia virus containing corresponding HIV-1 gene. RESULTS: HIV-1 peptide-specific HLA-B*3501-restricted CTL was induced in PBL of HIV-1 infected donors by in vitro stimulation with 11 out of 27 HLA-B*3501-binding HIV-1 peptides. The specific CTL induced with 10 peptides killed the cells infected with recombinant vaccinia virus expressing the corresponding HIV-1 proteins. Out of these HIV-1 peptide epitopes, two epitopes were also presented by HLA-B51 molecules. CONCLUSION: In addition to the four HLA-B35-restricted HIV-1 CTL epitopes that have been previously reported, nine HLA-B35-restricted HIV-1 CTL epitopes were identified in the present study. These multiple epitopes will be useful in studies for immunopathogenesis of AIDS.

Antigen Presentation↗
PubMed1996

[Effect of superoxide production on nitric oxide release from the pulmonary vascular endothelium during reperfusion after warm ischemia].

It has been reported that reperfusion injury results in the diminished nitric oxide (NO) release from the pulmonary vascular endothelium. However, this mechanism is completely unknown. We examined the effect of superoxide dismutase (SOD) on NO release at reperfusion. A rabbit lung was perfused with Krebs-Henselit buffer in a recirculation system. Cyclic GMP (cGMP) content in the lung effluent from the left ventricle was assayed in a time-dependent manner. In the control group, the lung was immediately perfused without interventing ischemia. In the warm ischemia and reperfusion group, the lung was reperfused after 30 min of warm ischemia. In the SOD group, SOD (60,000 U and 120,000 U) was administered at reperfusion after warm ischemia. The cGMP release in the warm ischemia and reperfusion group significantly decreased compared with the control group. In the SOD group, cGMP release was reversed with increasing doses of SOD, and the cGMP content was significantly reversed at all time points with SOD administration of 120,000 U. The impairement of cGMP release by reperfusion injury was restored by SOD administration. This data suggests that NO release from the endothelium may be quenched by superoxide anion generated at reperfusion. In lung transplantation, efforts must be pursued to preserve the endothelial function such as NO pathway.

Animals↗
PubMed1996

Enhancing effects of (2S,3S,4R)-1-O-(alpha-D-galactopyranosyl)-2-(N-hexacosanoylamino) -1,3,4-octadecanetriol (KRN7000) on antigen-presenting function of antigen-presenting cells and antimetastatic activity of KRN7000-pretreated antigen-presenting cells.

(2S,3S,4R)-1-O-(alpha-D-galactopyranosyl)-2-(N-hexacosanoylamino)- 1,3, 4-octadecanetriol (KRN7000), with an alpha-galactosylceramide structure, is an immunomodulator showing potent antimetastatic activities. In an in vitro study, KRN7000 potently stimulated proliferation and enhanced natural killer activity in spleen cells from BALB/c euthymic mice, but not BALB/c athymic (nu/nu) mice, suggesting that T cells play an important role in these activities. To study the detailed immunostimulatory mechanisms of KRN7000, syngeneic mixed leukocyte reactions were then performed using dendritic cell-enriched fractions (DCEFs) from spleens of BALB/c euthymic and athymic mice. In these studies, KRN7000 enhanced the antigen-presenting cell activities of the DCEFs. In addition, marked production of interleukin-2 and interferon-gamma in BALB/c euthymic mice was observed following treatment with KRN7000 in vitro and in vivo. Because of these strong immunostimulating effects of KRN7000, its antimetastatic effects were also evaluated. Adoptively transferred KRN7000-treated DCEF markedly prolonged the survival time of mice bearing B16 pulmonary metastases. These results demonstrate that KRN7000 may be useful for cancer therapy not only as an antitumor agent but also as an activator of antigen-presenting cells such as dendritic cells, which can be used for adoptive cellular therapy.

Adjuvants, Immunologic↗
PubMed1996

Brevican: a major proteoglycan in adult brain.

A diverse set of proteoglycans is expressed in the developing and adult brain. This is in stark contrast to the fact that most extracellular matrix components, including fibronectin, laminin, and collagens, are not expressed in adult brain parenchyma. This suggests that proteoglycans may play a major functional role in cell-cell and cell-matrix interactions in the brain. Brevican is a member of the aggrecan/versican family of proteoglycans, containing a hyaluronic acid-binding domain in its N-terminus and a lectin-like domain in its C-terminus. Brevican has the smallest core protein among this family and is one of the most abundant chondroitin sulfate proteoglycans in the adult brain. Expression of brevican is highly specific in the brain and increases as the brain develops. These observations suggest that brevican may play a role in maintaining the extracellular environment of mature brain as a major constituent of the adult brain extracellular matrix.

Aging↗
PubMed1996

Profile of T-cell receptor V beta gene usage of cytotoxic T cells induced by intrapleural administration of a streptococcal preparation, OK432, in malignant effusions.

T-cell receptor (TCR) gene rearrangements were analyzed in tumor-infiltrating lymphocytes (TIL) using the reverse transcription-polymerase chain reaction (RT-PCR) to determine whether oligoclonal expression of TCRV beta occurs in TIL, and if so, whether it is involved in the clinical response and mechanisms of locoregional immunotherapy using a streptococcal preparation, OK432. Patients with malignant effusion of various origins were treated with intrapleural administration of OK432, and clinical responses were assessed by cytological and chest X-ray examinations. Pleural exudate cells (PEC), obtained before and after the administration of OK432 (designated as pre- and OK432-PEC, respectively), were subjected to TCR analysis. Both pre-PEC and OK432-PEC showed highly diverse expressions of TCRV beta gene usage in either type of PEC. The frequency of TCRV beta 20 gene expression in OK432-PEC was significantly higher than in pre-PEC. Moreover, the over-expression of the TCRV beta 20 gene usage was also induced in the peripheral blood lymphocytes and pre-PEC of patients by in vitro OK432 stimulation, but not in the PBL of one healthy volunteer. Single-strand conformational polymorphism (SSCP) analysis revealed the clonotypes of these TCRV beta 20 genes. Autologous tumor-specific killing activity could be detected in OK432-PEC and was significantly reduced by treatment with a TCRV beta 20-specific monoclonal antibody. These findings suggest that the rearrangement of TCRV beta 20 gene usage may be involved in the autologous tumor-specific action of malignant effusions in the treatment with OK432.

Aged↗
PubMed1995

Blood and lymphatic vessel invasion as prognostic factors for patients with primary resected nonsmall cell carcinoma of the lung with intrapulmonary metastases.

BACKGROUND: The new classification of intrapulmonary metastases of lung cancer was proposed by the American Joint Committee on Cancer; however, the prognostic factors are heterogeneous and not yet fully clarified. In this study, the authors evaluated the prognostic factors for and the possible routes of intrapulmonary metastases. METHODS: The factors influencing the prognosis of primary resected nonsmall cell lung carcinomas with intrapulmonary metastasis in the resected specimens were evaluated according to the Cox proportional hazards model using a total of 66 nonsmall cell lung carcinomas. The possible routes of tumor spread via the blood or lymphatic vessels also were evaluated. RESULTS: The overall 5-year survival rate was 26.1%, and the statistical analysis of survival curves revealed a significant difference with regard to N classification (P = 0.042), site of intrapulmonary metastasis (P = 0.012), blood vessel invasion (P = 0.0046), and lymphatic vessel invasion (P = 0.0267); there were no significant differences in relation to age, sex, histology, differentiation, T classification, tumor size, stage, number of intrapulmonary metastases, or size of intrapulmonary metastasis. Multivariate analysis according to the Cox proportional hazards model identified a significant correlation between survival and blood vessel invasion (P = 0.044) and lymphatic vessel invasion (P = 0.042), suggesting independent prognostic significance. The correlation between site of intrapulmonary metastasis and the ratio of blood or lymphatic vessel invasion showed a significantly lower ratio of blood vessel invasion in cases with intrapulmonary metastases at sites central to the primary lesion or in different segment(s) compared with those in cases with intrapulmonary metastases at sites peripheral to the primary lesion or in ipsilateral different lobe(s), suggesting a possible lymphatic vessel route of tumor spread. CONCLUSION: Blood vessel and lymphatic vessel invasion are important clinical factors in evaluating prognosis and the route of tumor spread in primary resected nonsmall cell carcinoma with intrapulmonary metastasis.

Adult↗
PubMed1995

Anion-exchange high-performance liquid chromatographic assay of plasma lipoproteins.

A fast, accurate, and precise high-performance liquid chromatographic (HPLC) assay method for human plasma lipoproteins has been developed. The method includes complete separation of high-, low-, and very-low-density lipoproteins within 20 min using a DEAE-glucomannan gel with stepwise elution, enzymatic oxidation of cholesterol (following ester hydrolysis) followed by a two-step reaction to form a fluorogenic product, and fluorometric detection as the total cholesterol (TC) level of each lipoprotein. The calibration range is 5-1000 micrograms/ml for the TC level of 20-microliters plasma samples and the relative standard deviation (n = 5) of the precision at 5 micrograms/ml is less than 10%. Each lipoprotein level determined by this optimized HPLC method agrees well with levels determined by ultracentrifugation or precipitation methods. This new method was successfully applied to assays of plasma lipoproteins in various forms of hyperlipidemia.

Calibration↗
PubMed1995

cDNA cloning and the identification of an aggrecanase-like cleavage site in rat brevican.

Brevican is a member of the aggrecan family of chondroitin sulfate proteoglycans that is predominantly expressed in the nervous system. In the adult brain, the brevican core protein undergoes proteolytic cleavage and exists as a 145-kDa full-length form and an 80-kDa C-terminal fragment. We have determined the complete primary structure of rat brevican and the N-terminal amino acid sequence of the 80-kDa fragment. The results demonstrate that the cleavage of the brevican core protein occurs in a highly conserved region within a generally poorly conserved central domain, and that the sequence at the cleavage site shows intriguing similarities to the "aggrecanase" cleavage site in aggrecan. cDNA cloning of rat brevican has also revealed that the putative hyaluronic acid binding protein, BEHAB, is identical to the N-terminal half of brevican.

Aggrecans↗
PubMed1995

Functional analysis of aryl hydrocarbon receptor nuclear translocator interactions with aryl hydrocarbon receptor in the yeast two-hybrid system.

The aryl hydrocarbon receptor (AHR) mediates dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin)-induced transcriptional activation of a battery of genes by interaction with a cofactor, called aryl hydrocarbon receptor nuclear translocator (ARNT) protein. Both AHR and ARNT belong to a family of proteins that includes the Drosophila circadian-rhythm protein and "single-minded" protein. These proteins share a domain called the PAS domain. In addition to the PAS domain, both AHR and ARNT contain basic helix-loop-helix (bHLH) and glutamine (Q)-rich domains. The roles of these domains in the receptor-mediated transcriptional activation are not understood completely. By using the yeast two-hybrid system with the N-terminal half of AHR as a probe, which contains the bHLH and PAS regions, to screen cDNA libraries prepared from human lymphocytes and C57BL mouse liver for clones encoding proteins capable of binding to these regions, we isolated a partial ARNT cDNA clone. These results demonstrated that the N-terminal half of AHR is capable of interacting with ARNT in yeast (probably through the bHLH motif). A fusion protein containing the GAL4 DNA binding domain (DB) linked to the full-length AHR was not capable of activating expression of a reporter gene containing the GAL4 DNA binding site, suggesting that ligand-free AHR alone has no transactivating properties in yeast. However, the C-terminal portion (amino acid residues 580-797) of the AHR, including the Q-rich domain, could confer transactivation of the reporter gene expression in the same system, suggesting that the N-terminal portion of the AHR contains transcription repression properties. In contrast, GAL4(DB)-ARNT fusion protein was able to activate expression of the same reporter gene. Deletion analysis of ARNT revealed that the C-terminal 75 amino acids, including the Q-rich domain, exhibited full transactivation function in yeast and mammalian cells. These results revealed different structural organizations for the transactivation properties between AHR and ARNT, although both contained transactivation domains at the C-termini.

Animals↗
PubMed1995

Long-term production of human monoclonal antibodies by human-mouse heterohybridomas.

Production of monoclonal antibodies (mAbs) by fused somatic cells was first developed by Köhler and Milstein two decades ago, but its utilization for the production of human mAbs, particularly those bearing kappa chains, has been difficult because heterohybridomas formed with mouse myeloma cells are unstable and tend to lose certain of their human chromosomes. We have stabilized two such heterohybridomas over one year period and induced the production of kappa-bearing and lambda-bearing human mAb, respectively. Increased productivity was achieved by adding the Na+K(+)-ATPase inhibitor, ouabain and a cell mitosis inhibitor, cytochalasin B, to the cell culture media.

Animals↗
PubMed1995

Age-associated change of 8-hydroxyguanine repair activity in cultured human fibroblasts.

8-hydroxyguanine (8-OH-Gua) is a major oxidative DNA damage product. Its repair activity was determined in the human fibroblast cell line, TIG-3, during the aging process. The repair activity increased in the first part of the aging process and decreased in the latter part. The highest repair activity was observed at the age of 30 PDL. These results suggest that the defense capacity for replication errors due to oxidative DNA damage increases greatly when the cells are rapidly dividing.

Base Sequence↗
PubMed1995

Role of ADF/TRX and its inhibitor on the release of major basic protein from human eosinophils.

Adult T cell leukemia-derived factor (ADF)/Thioredoxin (TRX), originally defined as an IL-2 receptor alpha-chain/p55 inducer, has many cytokine-like activities. We reported that the release of major basic protein (MBP) from mature eosinophils stimulated with cytochalasin B and C5a were augmented after preincubation with recombinant ADF/TRX. The addition of a TRX specific inhibitor, BE40644, suppressed the augmentation of MBP release from mature eosinophils. It is suggested that BE40644 is applicable in allergic diseases associated with eosinophils.

Benzoquinones↗
PubMed1995

Vestibular inputs to the lateral tegmental field of the cat: potential role in autonomic control.

The lateral tegmental field (LTF), which is comprised of the lateral reticular formation near the obex, is an important integrative area involved in cardiovascular control and the production of emesis. Using neuroanatomical and electrophysiological techniques, we tested the hypothesis that LTF neurons receive vestibular inputs; the neurons studied included those projecting into the subretrofacial rostral ventrolateral medulla (sRVLM), which contains cells that make direct connections with sympathetic preganglionic neurons. Injections of the anterograde tracer PHA-L into the medial and inferior vestibular nuclei produced labeled terminals in the LTF. Electrical stimulation of the vestibular nerve affected the firing rate of LTF neurons, including approximately one-third of those antidromically activated from the sRVLM. The response latencies ranged from 1.5 to 20 ms, suggesting that the neurons received both direct and polysynaptic vestibular inputs from the vestibular nuclei. The LTF may be involved in the production of vestibulosympathetic reflexes and vestibular-elicited vomiting.

Animals↗
PubMed1995

Proteolytic fragmentation with high specificity of mouse immunoglobulin G. Mapping of proteolytic cleavage sites in the hinge region.

We report the results of fragmentation of mouse IgG by clostripain, lysyl endopeptidase, metalloendopeptidase, and V8 protease that have a narrower substrate specificity than papain and pepsin. A panel of mouse monoclonal switch variant antibodies with IgG1, IgG2a, and IgG2b subclasses were examined. Cleavage sites by these proteases were mapped on the hinge region of each of the IgG subclasses. It was demonstrated that lysyl endopeptidase can cleave the core hinge portion of IgG2a and IgG2b without perturbing the inter-chain disulfide bridges. Digestion products were successfully isolated by a combined use of protein A affinity chromatography and HPLC techniques. This is a first successful attempt of obtaining the F(ab')2 fragment of IgG2b by proteolytic digestion.

Alkylation↗
PubMed1995

Difficulties in obtaining monoclonal antibodies to subsets of human leukocytes, using neonatal tolerance induction in mice.

Many antigens are shared between different types of human leukocytes. In an effort to obtain new lineage-specific monoclonal antibodies, particularly antibodies to dendritic cells, we attempted to tolerize newborn mice to one type of leukocyte and then immunize the adults with another. We found that T cells, either unstimulated T cells or T blasts, were more effective at inducing neonatal tolerance than non-T cells or B cell lines. However, the tolerance that was achieved was not restricted to T cells, since we could not elicit from the tolerized mice a specific antibody response to a B cell line or to blood dendritic cells. Here we describe several efforts, all unsuccessful, to achieve cell specific immune responses in tolerant mice. The parameters we considered included the type of cell used to tolerize neonatal mice, the regimen of injections for inducing tolerance or eliciting immunity, and the use of several different adjuvants.

Animals↗
PubMed1995

Abundant expression of GLUT1 and GLUT3 in rat embryo during the early organogenesis period.

The developmental change of both GLUT1 and GLUT3 protein in rat embryonal and fetal brain was examined using Western blot analysis and immunohistochemistry. The brains were collected from fetuses (gestational days 10 to 20), newborn, and adult rats. On day 10, the levels of GLUT1 and GLUT3 expressions were twofold higher than those of adult levels, but thereafter decreased rapidly as the gestation progressed. The tissue distribution of GLUT1 and GLUT3 in embryo was apparently distinct. On day 10, GLUT1 was expressed in the neural tube, gut, heart and optic vesicle, while GLUT3 was expressed in the surface ectoderm and gut. Thus, high affinity glucose transporters may be required in the early organogenesis period because their energy requirement is completely dependent upon anaerobic glycolysis. GLUT3 may facilitate glucose transfer from amniotic fluid to the embryo and GLUT1 may supply glucose for use as an embryonal fuel.

Animals↗