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N Yamaguchi

Publications and source records attributed to N Yamaguchi.

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

Involvement of tumor necrosis factor-related apoptosis-inducing ligand in NK cell-mediated and IFN-gamma-dependent suppression of subcutaneous tumor growth.

Natural killer (NK) cells and interferon- (IFN) gamma have been implicated in immune surveillance against tumor development. Here we show tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), which is a type II membrane protein belonging to the TNF family and plays a critical role in the NK cell-mediated and IFN-gamma-dependent suppression of subcutaneous growth of TRAIL-sensitive tumors. Administration of a neutralizing monoclonal antibody against TRAIL promoted outgrowth of subcutaneously inoculated TRAIL-sensitive tumors (L929, LB27.4, and Renca) but not TRAIL-resistant tumors (P815 and B16). Such a protective effect of TRAIL against TRAIL-sensitive tumors was abrogated in NK cell-depleted or IFN-gamma-deficient mice. These results suggested a substantial role of TRAIL as the effector molecule that eliminates subcutaneously developing TRAIL-sensitive tumors.

Animals↗
PubMed2001

A mandatory role for STAT4 in IL-12 induction of mouse T cell CCR5.

IL-12 was recently shown to induce CCR5 on TCR-triggered mouse T cells. Considering that STAT4 is the most critical of IL-12 signaling molecules, this study investigated the role for STAT4 in the induction of CCR5 expression. IL-12R was induced by stimulation with anti-CD3 plus anti-CD28 mAb similarly on T cells from wild-type (WT) and STAT4-deficient (STAT4(-/-)) mice, but the levels of IL-12R induced on IFN-gamma-deficient (IFN-gamma(-/-)) T cells were lower compared with WT T cells. Exposure of TCR-triggered WT T cells to IL-12 induced CCR5 expression. In contrast, TCR-triggered STAT4(-/-) T cells failed to express CCR5 in response to IL-12. IL-12 stimulation induced detectable albeit reduced levels of CCR5 expression on IFN-gamma(-/-) T cells. Addition of rIFN-gamma to cultures of IFN-gamma(-/-) T cells, particularly to cultures during TCR triggering resulted in restoration of CCR5 expression. However, CCR5 expression was not induced in STAT4(-/-) T cells by supplementation of rIFN-gamma. These results indicate that for the induction of CCR5 on T cells, 1) STAT4 plays an indispensable role; 2) such a role is not substituted by simply supplementing rIFN-gamma; and 3) IFN-gamma amplifies CCR5 induction depending on the presence of STAT4.

Animals↗
PubMed2001

Detection of Aleutian disease antibodies in feral American mink in southern England.

Fourteen of 27 American mink (Mustela vison) trapped in the upper Thames region were positive for anti-Aleutian disease antibodies. This demonstration of the occurrence of this viral disease in a feral American mink population suggests that it could threaten populations of at least two protected mustelids, the otter (Lutra lutra) and the polecat (Mustela putorius), and may also play a role in the apparent decline of local mink populations in Britain.

Age Factors↗
PubMed2001

Alternative splicing isoforms of hippostasin (PRSS20/KLK11) in prostate cancer cell lines.

BACKGROUND: Hippostasin is a kallikrein-like protease (PRSS20/KLK11), which is expressed preferentially in the hippocampus and prostate. We have reported that alternative splicing variants of human hippostasin are regulated in a tissue-specific manner. Brain-type hippostasin consists of 250 amino acids including a typical signal sequence, and is expressed in the brain and prostate. The prostate-type hippostasin, which has 32 extra amino acids at the N-terminal end, is expressed only in the prostate. METHODS: We analyzed the expression and localization of hippostasin in normal prostate tissue, BPH tissue, and prostate cancer cell lines. We performed northern blotting, in situ hybridization, immunohistochemistry, and RT-PCR. RESULTS: Hippostasin mRNA is expressed preferentially in the normal prostate and weakly in the testis. It was detected in prostate secretory epithelium. Hippostasin protein was localized in the prostate secretory epithelium, and western blotting showed that hippostasin was present in semen. All tested prostate cancer cell lines, including PSA-negative cell lines, expressed hippostasin. Interestingly, all the prostate cancer cell lines expressed only brain-type but not prostate-type hippostasin, while normal prostate and BPH expressed both types of hippostasin CONCLUSIONS: Our results suggest the possibility that hippostasin may be a useful marker by which prostate cancer and BPH can be distinguished.

Biomarkers, Tumor↗
PubMed2001

Humanization and epitope mapping of neutralizing anti-human Fas ligand monoclonal antibodies: structural insights into Fas/Fas ligand interaction.

Fas ligand (L)/CD95L, a proapoptotic member of the TNF family, is a potential target for clinical intervention in various diseases. In the present study, we generated a humanized anti-human FasL mAb and characterized the epitopes of neutralizing mAbs by extensive alanine-scanning mutagenesis of human FasL. The predicted molecular model of FasL trimer revealed that the mAbs recognize largely overlapped conformational epitopes that are composed of two clusters, one around the outer tip-forming D-E loop and another near the top of FasL. Both of these sites on FasL are critically involved in the direct interaction with the corresponding receptor, Fas. These results suggest that the mAbs efficiently neutralize FasL cytotoxicity by masking both of these FasL/Fas contact sites.

Amino Acid Sequence↗
PubMed2001

Induction of apoptosis in human T cells by Actinobacillus actinomycetemcomitans cytolethal distending toxin is a consequence of G2 arrest of the cell cycle.

We have previously shown that Actinobacillus actinomycetemcomitans produces an immunosuppressive factor that is encoded by the cdtB gene, which is homologous to a family of cytolethal distending toxins (Cdt) expressed by several Gram-negative bacteria. Moreover, we have shown that CdtB impairs lymphocyte function by inducing G(2) arrest of the cell cycle. We now report that both CdtB as well as an extract prepared from an Escherichia coli strain that expresses all three of the A. actinomycetemcomitans cdt genes (rCdtABC) induce apoptosis. Pretreatment of lymphocytes with either CdtB or rCdtABC leads to DNA fragmentation in activated lymphocytes at 72 and 96 h. No DNA fragmentation was induced in nonactivated cells. Flow cytometric analysis of the Cdt-treated lymphocytes demonstrates a reduction in cell size and an increase in nuclear condensation. Mitochondrial function was also perturbed in cells pretreated with either CdtB or rCdtABC. An increase in the expression of the mitochondria Ag, Apo 2.7, was observed along with evidence of the development of a mitochondrial permeability transition state; this includes a decrease in the transmembrane potential and elevated generation of reactive oxygen species. Activation of the caspase cascade, which is an important biochemical feature of the apoptotic process, was also observed in Cdt-treated lymphocytes. Overexpression of the bcl-2 gene in the human B lymphoblastoid cell line, JY, led to a decrease in Cdt-induced apoptosis. Interestingly, Bcl-2 overexpression did not block Cdt-induced G(2) arrest. The implications of our results with respect to the immunosuppressive functions of Cdt proteins are discussed.

Aggregatibacter actinomycetemcomitans↗
PubMed2001

Characterization of a brain-related serine protease, neurosin (human kaillikrein 6), in human cerebrospinal fluid.

Neurosin (also known as zyme or protease M) is a trypsin-like serine protease dominantly expressed in the human brain. According to the official nomenclature, this gene is now designated as human kallikrein 6 (KLK6) and the protein is designated hK6. To investigate the metabolism of neurosin in human brain, neurosin contained in the human cerebrospinal fluid (CSF) was analyzed. Neurosin was detected in the all CSFs tested by Western blot analysis using an anti-neurosin monoclonal antibody. We purified neurosin from CSF (CSF-neurosin) using an immunoaffinity chromatography and an anion-exchange chromatography. SDS-PAGE revealed that the purified protein has a relative mol. mass (Mr) of 25,000 Da. The observed sequence of the N-terminal amino acids, Glu-Glu-Gln-Asn-Lys, of the purified CSF-neurosin was identical to the sequence of N-terminal of the pro-enzyme form, which is presumed to have no enzyme activity. CSF-neurosin neither showed any enzyme activity to Boc-Phe-Ser-Arg-4-methylcoumaryl-7-amide, which is known to be degraded by the mature neurosin, nor cleaved gelatin. To confirm that the major portion of CSF-neurosin is present in the pro-enzyme form, Western blot analysis using antibodies specific to the pro- or mature enzyme was carried out. The antibody against the mature neurosin fragment did not react with CSF-neurosin. Only the antibody against the pro-enzyme fragment detected CSF-neurosin. Thus, our results suggest that neurosin is present as an inactive pro-enzyme in the human CSF.

Amino Acid Sequence↗
PubMed2001

Identification of apocalmodulin and Ca2+-calmodulin regulatory domain in skeletal muscle Ca2+ release channel, ryanodine receptor.

Fusion proteins and full-length mutants were generated to identify the Ca(2+)-free (apoCaM) and Ca(2+)-bound (CaCaM) calmodulin binding sites of the skeletal muscle Ca(2+) release channel/ryanodine receptor (RyR1). [(35)S]Calmodulin (CaM) overlays of fusion proteins revealed one potential Ca(2+)-dependent (aa 3553-3662) and one Ca(2+)-independent (aa 4302-4430) CaM binding domain. W3620A or L3624D substitutions almost abolished completely, whereas V3619A or L3624A substitutions reduced [(35)S]CaM binding to fusion protein (aa 3553-3662). Three full-length RyR1 single-site mutants (V3619A,W3620A,L3624D) and one deletion mutant (Delta4274-4535) were generated and expressed in human embryonic kidney 293 cells. L3624D exhibited greatly reduced [(35)S]CaM binding affinity as indicated by a lack of noticeable binding of apoCaM and CaCaM (nanomolar) and the requirement of CaCaM (micromolar) for the inhibition of RyR1 activity. W3620A bound CaM (nanomolar) only in the absence of Ca(2+) and did not show inhibition of RyR1 activity by 3 microm CaCaM. V3619A and the deletion mutant bound apoCaM and CaCaM at levels compared with wild type. V3619A activity was inhibited by CaM with IC(50) approximately 200 nm, as compared with IC(50) approximately 50 nm for wild type and the deletion mutant. [(35)S]CaM binding experiments with sarcoplasmic reticulum vesicles suggested that apoCaM and CaCaM bind to the same region of the native RyR1 channel complex. These results indicate that the intact RyR1 has a single CaM binding domain that is shared by apoCaM and CaCaM.

Calcium↗
PubMed2001

A role of interferon-gamma (IFN-gamma) in tumor immunity: T cells with the capacity to reject tumor cells are generated but fail to migrate to tumor sites in IFN-gamma-deficient mice.

IFN-gamma-deficient (IFN-gamma-/-) mice induce potent in vitro immune responses such as anti-allo mixed lymphocyte reaction and CTL responses, whereas they often fail to exhibit in vivo immunity. Here, we investigated whether there exists a defect in tumor rejection responses and if so, which process of responses is impaired. IFN-gamma-/- and wild-type (WT) BALB/c mice were immunized with attenuated syngeneic CSA1M tumor cells. The capacity of T cells to mediate tumor protection was examined in Winn assays to assess the growth of tumor cells admixed with tumor-sensitized T cells. Splenic T cells from both groups of mice exhibited comparable levels of tumor-neutralizing activity. When portions of immunized mice were directly challenged with viable tumor cells, tumor rejection was induced only in WT mice. CD4(+) and CD8(+) T-cell infiltration were observed at the site of tumor challenge in WT mice, whereas such a T-cell infiltration did not occur in IFN-gamma-/- mice. Similarly, splenic T cells from interleukin 12-treated CSA1M-bearing IFN-gamma-/- and WT mice neutralized tumor cells at comparable efficacies in Winn assays. However, the migration of these T cells to tumor masses and the resultant interleukin 12-induced tumor regression took place in WT mice, but neither intratumoral T-cell infiltration nor tumor regression occurred in IFN-gamma-/- mice. These results indicate a critical requirement for IFN-gamma in the process of inducing T-cell migration to tumor sites rather than of generating antitumor protective T cells.

Animals↗
PubMed2001

Calmodulin binding and inhibition of cardiac muscle calcium release channel (ryanodine receptor).

Metabolically (35)S-labeled calmodulin (CaM) was used to determine the CaM binding properties of the cardiac ryanodine receptor (RyR2) and to identify potential channel domains for CaM binding. In addition, regulation of RyR2 by CaM was assessed in [(3)H]ryanodine binding and single-channel measurements. Cardiac sarcoplasmic reticulum vesicles bound approximately four CaM molecules per RyR2 tetramer in the absence of Ca(2+); in the presence of 100 microm Ca(2+), the vesicles bound 7.5 CaM molecules per tetramer. Purified RyR2 bound approximately four [(35)S]CaM molecules per RyR tetramer, both in the presence and absence of Ca(2+). At least four CaM binding domains were identified in [(35)S]CaM overlays of fusion proteins spanning the full-length RyR2. The affinity (but not the stoichiometry) of CaM binding was altered by redox state as controlled by the presence of either GSH or GSSG. Inhibition of RyR2 activity by CaM was influenced by Ca(2+) concentration, redox state, and other channel modulators. Parallel experiments with the skeletal muscle isoform showed major differences in the CaM binding properties and regulation by CaM of the skeletal and cardiac ryanodine receptors.

Allosteric Regulation↗
PubMed2001

Growth hormone interferes with the progression of myocarditis in rats.

In this study, we investigated whether recombinant human growth hormone (rhGH) influences the progression of myocarditis. We induced experimental autoimmune myocarditis in F344 rats by subcutaneous injection of cardiac myosin, and divided the rats into three groups: (1) control group, saline injection; (2) pre-treated group, subcutaneous injection of rhGH (100 mIU/rat/day for 10 days) before induction of experimental autoimmune myocarditis; and (3) post-treated group, subcutaneous injection of rhGH (100 mIU/rat/day for 10 days) after induction of experimental autoimmune myocarditis. On the 35th day after induction of experimental autoimmune myocarditis, all rats were sacrificed and the hearts were examined. The increase in body weight was smaller in the control group than the pre-treated group and the rate of heart weight/body weight was larger in the control group than in the two treated groups. Histopathologically, rats in the control group showed multifocal infiltration by inflammatory cells, mainly neutrophils, lymphocytes and macrophages, extensive fibrosis, and a higher proportion of mast cells in the inflamed region. In contrast, rats in the two treated groups showed only minor changes. We found that rhGH did not influence the distribution of lymphocytes in peripheral blood in the three groups, and that rhGH induced G1 checkpoint dysfunction, thereby arresting the cell cycle in G1 and inhibiting the proliferation of mast cells in vitro. These findings suggest a possible role for mast cells in the progression of myocarditis and the rhGH may be a candidate for use as a new tool to treat myocarditis.

Animals↗
PubMed2001

Remission of the renal involvement in a patient with primary Sjögren's syndrome (SS) after pulse high-dose corticosteroid infusion therapy.

We report the case of a young female patient with primary Sjögren's syndrome (SS). In addition to sicca symptoms she also suffered from progressive renal insufficiency and renal tubular acidosis (RTA). She was treated with three sets of pulse high-dose corticosteroid infusion and subsequent low-dose corticosteroid oral administration. When the efficacy was evaluated about 6 months after the start of the therapy, dramatic improvements were seen with no adverse effects, not only in laboratory tests but also histopathologically, as indicated by the repeat kidney biopsy. This suggests that renal involvements of SS might be reversible in some cases, and that there might be a clinical benefit of pulse high-dose corticosteroid infusion therapy in SS with progressive renal involvement.

Acidosis, Renal Tubular↗
PubMed2001

Japanese experience of telemedicine in oncology.

We started telemedicine projects from 1990 with a telepathology system within Tsukiji Campus of National Cancer Center. In 1994, we connected Tsukiji Campus and Kashiwa Campus by 6 Mbps optical fiber leased line using IP protocol for data transmission, for teleconference, telepathology, and teleradiology projects. We also started connection of regional cancer centers and are now forming a cancer center network of 14 cancer centers. We are at present organizing 130 teleconferences per year with an attendance of more than 16000 people as summary. We have also used a high-resolution image transferring system, such as SHD (2000 pixelsx2000 pixels resolution) system on one side, and an economical telemedicine system using JAVA and a WWW browser (NCC_image) on the other side. We think that providing information is another field of telemedicine. We began the experimental gopher and WWW service in 1993. We are now providing official up-to-date cancer information for patients and healthcare professionals. We are getting more than 400000 hits per month. We are also providing a teleconference video session which is held every week on the Internet using a Real Video system with synchronized slide presentation on the WWW browser. We are also organizing a Cancer Image Reference Database System including DICOM images with viewer software. This paper is a summary of the telemedicine projects performed at the National Cancer Center.

Community Networks↗
PubMed2001

Synergistic interaction between Helicobacter pylori gastritis and diet in gastric cancer.

Infection with Helicobacter pylori increases the risk of gastric cancer. One possible mechanism is the higher likelihood of malignant transformation due to inflammatory responses in the epithelium. An alternative explanation is that these inflammatory responses induce chronic gastritis associated with decreased acidity in the stomach, which in turn increases the endogenous formation of carcinogenic N-nitroso compounds. Inflammatory responses seem to trigger two different causal pathways: one for the diffuse type of gastric cancer and the other for the intestinal type. The striking geographic variability in intestinal gastric cancer can be explained by the synergistic interaction between H. pylori infection and dietary factors, such as intake of salt and ascorbic acid. Screening and eradication of this organism, together with appropriate dietary modifications, offer promise in countries with a high prevalence of H. pylori infection and high risk of gastric cancer, but the safety of such interventions needs to be ensured.

Diet↗
PubMed2001

Involvement of tumor necrosis factor-related apoptosis-inducing ligand in surveillance of tumor metastasis by liver natural killer cells.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in various tumor cells in vitro, but its physiological role in tumor surveillance remains unknown. Here, we report that TRAIL is constitutively expressed on murine natural killer (NK) cells in the liver and plays a substantial role in suppressing tumor metastasis. Freshly isolated NK cells, but not natural killer T cells or ordinary T cells, from the liver expressed cell surface TRAIL, which was responsible for spontaneous cytotoxicity against TRAIL-sensitive tumor cells in vitro along with perforin and Fas ligand (FasL). Administration of neutralizing monoclonal antibody against TRAIL significantly increased experimental liver metastases of several TRAIL-sensitive tumor cell lines. Such an anti-metastatic effect of TRAIL was not observed in NK cell-depleted mice or interferon-gamma-deficient mice, the latter of which lacked TRAIL on liver NK cells. These findings provide the first evidence for the physiological function of TRAIL as a tumor suppressor.

Animals↗
PubMed2001

Histologic study of the regeneration process of human hair follicles grafted onto SCID mice after bulb amputation.

This study examines histologically the degeneration and subsequent regeneration processes of human hair follicles whose bulb is severely damaged. Human scalp hair follicles were isolated and grafted onto immunodeficient mice after their bulb was amputated. On day 14, thickening and corrugation of the vitreous membrane, apoptosis of follicular keratinocytes, and regression of the lower portion of the follicles were observed. By day 20, mesenchymal cells had accumulated around the lower end of the follicles. From day 14 through 50, the follicular regression and apoptosis continued, and between days 30 and 40 the follicles became maximally shortened, and the vitreous membrane disappeared. By day 50 the lower end of the follicles had become cup-shaped, and the cup surrounded an aggregate of mesenchymal cells that corresponded to the dermal papilla. By day 60, all the grafted follicles had developed into anagen VI follicles, and the apoptosis had ceased. These results indicate that human scalp hair follicles whose bulb is completely destroyed enter into dystrophic telogen after restoration of the dermal papilla, then into anagen, and that the duration of the dystrophic telogen is shorter than that of the normal hair cycle.

Animals↗
PubMed2001

A prospective clinical study on inhaled nitric oxide therapy for neonates in Japan.

BACKGROUND: This is the first report about a prospective clinical investigation to study the efficacy and safety of nitric oxide (NO) inhalation in infants with persistent pulmonary hypertension of the newborn (PPHN) in Japan. METHODS: Patients in the present study had to meet the following entry criteria: (i) they had to be younger than 7 days of age; (ii) they had to have evidence of PPHN as defined by echocardiograph; (iii) they had to have severe systemic hypoxemia under mechanical ventilation at 100% oxygen supplementation; and (iv) they had to have a failure to respond to conventional therapies. Patients were excluded from this trial if they had any of the following: hypoplastic lung, structural cardiac lesions or severe multiple anomalies. RESULTS: Nitric oxide inhalation therapy was performed in 68 infants who had severe PPHN at 18 hospitals between May 1995 and May 1997. At birth, 21 of 68 infants (31%) weighed less than 1,500 g and 39 infants weighed more than 2,500 g. The diagnoses associated with PPHN were as follows: 27 infants had meconium aspiration syndrome, 15 infants had dry lung syndrome, nine infants had congenital diaphragmatic hernia, six infants had respiratory distress syndrome, three infants had pneumonia and eight infants had other diagnoses. The mean oxygenation index (OI) before NO inhalation therapy in 68 infants was 43.2; 55 infants (81%) had good responses. CONCLUSIONS: These results may be valuable for further randomized controlled and double-blind trials in Japan to evaluate whether NO inhalation therapy is more effective than conventional therapy in infants with severe PPHN.

Administration, Inhalation↗