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Biomedical subjects

M Taniguchi

Publications and source records attributed to M Taniguchi.

At least 199 records · Page 11Linked to original sources
PubMed2000

The interface between innate and acquired immunity: glycolipid antigen presentation by CD1d-expressing dendritic cells to NKT cells induces the differentiation of antigen-specific cytotoxic T lymphocytes.

In vivo administration of NKT cell ligand, alpha-galactosylceramide (alpha-GalCer), caused the activation of NKT cells to induce a strong NK activity and cytokine production by CD1d-restricted mechanisms. Surprisingly, we also found that alpha-GalCer induced the activation of immunoregulatory cells involved in acquired immunity. Specifically, in vivo administration of alpha-GalCer resulted in the induction of the early activation marker CD69 on CD4(+) T cells, CD8(+) T cells and B cells in addition to macrophages and NKT cells. However, no significant induction of CD69 was observed on cells from CD1d- or V(alpha)14 NKT-deficient mice, indicating an essential role for the interaction between NKT cells and CD1d-expressing dendritic cells (DC) in the activation of acquired immunity in response to alpha-GalCer. Indeed, in vivo injection of alpha-GalCer resulted not only in the activation of NKT cells but also in the generation of CD69(+)CD8(+) T cells possessing both cytotoxic T lymphocyte (CTL) activity and IFN-gamma-producing ability. Tumor-specific CTL generation was also accelerated by alpha-GalCer. The critical role of CD40-CD40 ligand (CD40L)-mediated NKT-DC interaction during the development of CD69(+)CD8(+) CTL by alpha-GalCer was demonstrated by blocking experiments using anti-CD40L mAb. These findings provide direct evidence for a critical role of CD1d-restricted NKT cells and DC in bridging innate and acquired immunity.

Adjuvants, Immunologic↗
PubMed2000

CD4(+) v(alpha)14 NKT cells play a crucial role in an early stage of protective immunity against infection with Leishmania major.

The roles of gamma delta T, NK and NKT cells in an early stage of protective immunity against infection with Leishmania major were investigated. Further, the contribution of these innate cells to the expression of 65 kDa heat shock protein (HSP65) in host macrophages was examined, since we found previously that this expression prevents apoptotic death of infected macrophages and is a crucial step in the acquisition of protective immunity against infection with various obligate intracellular protozoa including L. major. C57BL/6 and DBA/2 mice were found to be resistant against the infection on the basis of the parasite burden in their regional lymph nodes, and to strongly express HSP65 in their macrophages, whereas BALB/c mice were susceptible and barely expressed the HSP65. In those resistant mice, CD4(+) NKT cells prominently increased in their regional lymph node and were the main effector cells at least for an early stage of the protective immunity and for the HSP65 expression, whereas this subset did not increase in susceptible BALB/c mice. Further, neither gamma delta T nor NK cells in resistant mice contributed to those protective immune responses. The NKT cell subset bore CD3, CD4, TCR alpha beta, IL-2R beta and NK1.1 but scarcely asialo-GM(1). Moreover, this effector subset was confirmed to be V(alpha)14 NKT cells by using J(alpha)281(-/-) mice.

Animals↗
PubMed2000

The promoter for the maize C4 pyruvate, orthophosphate dikinase gene directs cell- and tissue-specific transcription in transgenic maize plants.

The pyruvate,orthophosphate dikinase (PPDK) gene coding the chloroplast enzyme involved in C4 photosynthesis has a dual promoter system. The first promoter is responsible for the transcription of a larger transcript and its product is targeted to the chloroplast (hence, it is designated as C4Pdk promoter) while the second promoter is responsible for the transcription of a smaller transcript and its product remains in the cytosol. In this study, chimeric maize C4Pdk promoter (0.9 or 1.5 kb)-beta-glucuronidase or luciferase fusion genes were introduced into maize plants by Agrobacterium-mediated transformation. The cell- and tissue-specificities of the maize C4Pdk promoter in the transgenic maize plants were examined by histochemical and enzymic activity analyses of the reporters in different photosynthetic cells and tissues. The results showed that the reporter proteins are almost exclusively localized in leaf mesophyll cells. Among the tissues tested, leaf blade had the highest reporter activities with sheath exhibiting about 10% of the activities in blade. Husk, stem, tassel and root had no or very little reporter activities. Taken together, these results suggest that the maize C4Pdk promoter is specifically transcribed in the mesophyll cells of leaf blade and to a much less extent in the mesophyll cells of sheath, but not in leaf bundle sheath cells or other tissues. Furthermore, the 0.9 kb maize C4Pdk promoter sequences appear to contain the necessary cis-acting elements for its cell- and organ-specific expression.

Gene Expression Regulation, Enzymologic↗
PubMed2000

Genes encoding pseudo-response regulators: insight into His-to-Asp phosphorelay and circadian rhythm in Arabidopsis thaliana.

In the higher plant, Arabidopsis thaliana, results from recent intensive studies suggested that His-to-Asp phosphorelay mechanisms are involved presumably in propagation of environmental stimuli, such as phytohormones (e.g. ethylene and cytokinin). Here we identified and characterized a set of novel Arabidopsis genes whose products considerably resemble the authentic response regulators (ARR-series) of Arabidopsis in the sense that they have a phospho-accepting receiver-like domain. However, they should be discriminated from the classical ones in the strict sense that they lack the invariant phospho-accepting aspartate site. They were thus named APRRs (Arabidopsis pseudo-response regulators). Two such representatives, APRR1 and APRR2, were characterized extensively through cloning of the corresponding cDNAs, in terms of their structural designs, biochemical properties, subcellular localization in plant cells, and expression profiles at the transcriptional level. The result of in vitro phosphorylation experiment with the Arabidopsis AHP phosphotransmitter suggested that the pseudo-receivers have no ability to undergo phosphorylation. The result of transient expression assay with onion epidermal cells showed that the GFP-APRR1 fusion protein has an ability to enter into the nuclei. The C-terminal domain of APRR1, termed CONSTANS-motif, appears to be responsible for the nuclear-localization. The most intriguing result was that the accumulation of APRR1 transcript is subjected to a circadian rhythm. The APRR1 protein is identical to the one that was recently suggested to interact with the ABI3 (ABISCISIC ACID INSENSITIVE3) protein. These are discussed with special reference to the His-to-Asp phosphorelay signal transduction and circadian rhythm in Arabidopsis thaliana.

Amino Acid Sequence↗
PubMed2000

TTV positivity and transfusion history in non-B, non-C hepatocellular carcinoma compared with HBV- and HCV-positive cases.

The prevalence of TT virus (TTV) and its rate of transmission through transfusion were investigated to determine its possible hepatocarcinogenic role in non-B, non-C hepatocellular carcinoma (HCC) as compared with that in hepatitis B virus (HBV)- and hepatitis C virus (HCV)-positive HCC. Its transfection route in TTV-positive cases was also studied. Serum was positive for TTV in 77.8% (7/9) of HBV-positive, 36.4% (12/33) of HCV-positive, and 63. 6% (7/11) of non-B, non-C cases of HCC. The rate of transmission through transfusion was 52.4% (11/21) in HBV-positive, 40.1% (61/152) in HCV-positive, 33.3% (2/6) in HBV+HCV-positive, and 40% (8/20) in non-B, non-C HCCs, while it was 48.3% (14/29) in TTV-positive and 39.3% (11/28) in TTV-negative cases. The association between TTV and HCC was limited, and the main route of infection of TTV was not through transfusion.

Adult↗
PubMed2000

CD4(+) Valpha14 natural killer T cells are essential for acceptance of rat islet xenografts in mice.

Pancreatic islet transplantation represents a potential treatment for insulin-dependent diabetes mellitus. However, the precise cellular and molecular mechanisms of the immune reactions against allogeneic and xenogeneic transplanted islets remain unclear. Here, we demonstrate that CD4(+) Valpha14 natural killer T (NKT) cells, a recently identified lymphoid cell lineage, are required for the acceptance of intrahepatic rat islet xenografts. An anti-CD4 mAb, administrated after transplantation, allowed islet xenografts to be accepted by C57BL/6 mice, with no need for immunosuppressive drugs. The dose of anti-CD4 mAb was critical, and the beneficial effect appeared to be associated with the reappearance of CD4(+) NKT cells at around 14 days after transplantation. Interestingly, rat islet xenografts were rejected, despite the anti-CD4 mAb treatment, in Valpha14 NKT cell-deficient mice, which exhibit the normal complement of conventional lymphoid cells; adoptive transfer of Valpha14 NKT cells into Valpha14 NKT cell-deficient mice restored the acceptance of rat islet xenografts. In addition, rat islet xenografts were accepted by Valpha14 NKT mice having only Valpha14 NKT cells and no other lymphoid cells. These results indicate that Valpha14 NKT cells play a crucial role in the acceptance of rat islet xenografts in mice treated with anti-CD4 antibody, probably by serving as immunosuppressive regulatory cells.

Animals↗
PubMed2000

Inhibitory effect of natural furanocoumarins on human microsomal cytochrome P450 3A activity.

To investigate the possible drug interaction with herbal medicine, furanocoumarin derivatives isolated from several Umbelliferous crude drugs were examined for their inhibitory effects on a typical human drug metabolizing enzyme, cytochrome P450 3A (CYP3A). Most furanocoumarins tested at 0.1 mM reduced microsomal testosterone 6beta-hydroxylation as an index of CYP3A activity to less than 50% of the control. In particular, the dimer and trimer derivatives of furanocoumarins showed striking inhibition, whose potencies were similar to that of a typical CYP3A inhibitor, ketoconazole. Preincubation of dimer types of furanocoumarins increased suppression but not most of the monomer derivatives, suggesting that the inhibition on CYP3A activity was caused by at least plural mechanisms. These results raised the possibility that the furanocoumarin containing herbal medicines may alter pharmacokinetics of co-ingested drugs similar to the case with grapefruit juice.

Aryl Hydrocarbon Hydroxylases↗
PubMed2000

Cloning and expression of the Momordica charantia trypsin inhibitor II gene in silkworm by using a baculovirus vector.

MCTI-II (Momordica charantia trypsin inhibitor II) isolated from bitter gourd (Momordica charantia LINN.) seeds is one of the serine protease inhibitors of the squash family. We cloned cDNA that encodes MCTI-II and constructed an expression system for MCTI-II by using a baculovirus vector. The recombinant baculovirus was inoculated to early fifth-instar larvae of the silkworm (strain: Shunrei x Shougetsu). Four days after infection, the hemolymph of silkworm larvae was collected and the recombinant protein was purified. Two kinds of expressed MCTI-II protein were obtained. An amino acid sequence analysis of the two proteins indicates that both were similar to the authentic inhibitor, except for the addition of a tripeptide derived from the vector at the N-terminus. One of the two inhibitors (MCTI-II A) resulted in a single PTH-amino acid in each Edman degradation cycle, while the other (MCTI-II B) resulted in two PTH-amino acids, suggesting the occurrence of cleavage of the reactive site. The inhibitory activities of MCTI-II expressed toward trypsin are examined in terms of the Ki value, these being 6.4 x 10(-10)M for MCTI-II A and 5.2 x 10(-10) M for MCTI-II B.

Amino Acid Sequence↗
PubMed2000

Establishment of a visible peritoneal micrometastatic model from a gastric adenocarcinoma cell line by green fluorescent protein.

To establish a visible peritoneal micrometastatic model, an enhanced green fluorescent protein (EGFP) expressing plasmid vector was transfected into the gastric cancer cell line, MKN-45. Highly expressing EGFP cells were injected into the peritoneal cavity of nude mice. Then, the peritoneum and abdominal organs were harvested and observed on days 1, 4 and 7. Fluorescence stereomicroscopy identified peritoneal micrometastases that had been undetected by stereomicroscopy. Micrometastases as small as a single cell are detectable in this model. This peritoneal micrometastatic model should be a useful tool for research on metastasis of gastric cancer.

Adenocarcinoma↗
PubMed2000

[Sudden cardiac arrest after induction of general anesthesia: a case report].

We experienced sudden cardiac arrest after induction of general anesthesia using isoflurane. The patient had had paroxysmal atrial fibrillation for one year and had been treated with digoxin and cibenzoline succinate. Sinus rhythm appeared soon after the start of closed chest compression. However cardiac arrest recurred, and we inserted a temporary pacemaker catheter to stabilize the circulatory status. She awoke from anesthesia without any complications. The diagnosis of sick sinus syndrome (SSS) was made postoperatively and she had a permanent pacemaker implanted. We thought that the hidden SSS had been the cause of this sudden cardiac arrest.

Aged↗
PubMed2000

[Postoperative pancreatitis after total hip replacement under general anesthesia].

A 61 year old male patient developed postoperative pancreatitis after total hip replacement under general anesthesia with sevoflurane. The patient had chronic renal failure and was receiving hemodialysis. The estimated intraoperative blood loss was 1500 ml, and 1200 ml of blood was administered. The intraoperative mean blood pressure was 60 to 70 mmHg and the central venous pressure at the end of anesthesia was 0 mmHg. Postoperatively he complained of severe upper abdominal pain. On the 1st postoperative day serum amylase level increased to fifteen times of the normal level. He complained again of severe abdominal pain on hemodialysis. From these episodes, we estimate that the circulatory disturbance of pancreas is the cause of this postoperative pancreatitis.

Acute Disease↗
PubMed2000

Expression of B cell-associated transcription factors in B-cell precursor acute lymphoblastic leukemia cells: association with PU.1 expression, phenotype, and immunogenotype.

B-lymphocyte development progresses through discrete stages characterized by regular DNA rearrangements of the immunoglobulin (Ig) loci that lead to the transcription of Ig genes and expression of B-cell antigen receptors. These developmental processes can also be distinguished by the expression of specific cell-surface markers. Therefore, rearrangement of the Ig, T-cell receptor (TCR) genes, and surface markers are generally considered as useful markers of the B- and T-cell lineage in lymphoproliferative disorders. However, concomitant rearrangement of Ig and TCR genes (double genotype) has been reported in the most immature lymphoid malignancies (lineage promiscuity), mainly in B-cell precursor acute lymphoblastic leukemia (pre-B ALL), but the mechanism is not fully understood. DNA rearrangements and specific cell-surface markers are regulated by several specific transcription factors. To better characterize the lineage promiscuity, we studied the relationship among the expression of lymphoid-associated transcription factors, phenotype, and immunogenotype. Rearrangement of the Ig light chain kappa gene was found in 37% of pre-B ALL samples and in all B-cell chronic lymphocytic leukemia (B-CLL) samples. Rearrangement of TCR gamma gene was shown in 40% of pre-B ALL samples but was not detected in any of the B-CLL samples. Among the tested B cell-associated transcription factors, Pax5 and E47 genes were expressed in all pre-B ALL and B-CLL samples. RAG-1 gene was expressed in all pre-B ALL samples but not in the B-CLL samples. Oct-2 gene was expressed in 82% of pre-B ALL and all B-CLL samples. The expression of PU.1 gene was shown in 56% of pre-B ALL but not in the B-CLL samples. Interestingly, the samples of pre-B ALL, which did not express the PU.1 gene, showed a significantly high frequency of TCR gamma gene rearrangement. This phenomenon was not found with Oct-2 gene expression. These findings suggest that absence of PU.1 expression may result in lineage promiscuity, such as the simultaneous rearrangements of Ig and TCR genes in pre-B ALL cells.

Adult↗
PubMed2000

[Nasal continuous positive airway pressure and noninvasive positive ventilation in the treatment of sleep apnea/hypopnea syndrome].

The main medical treatment of moderate to severe obstructive sleep apnea/hypopnea syndrome is nasal continuous positive airway pressure(nCPAP). When compliance of the patient is low due to nasal or oral dryness, heated humidifier is added to nCPAP. In Japan frequent complaints such as nasal cold and dryness were observed in winter because of infrequent air conditioning in the sleeping room. In the case of dyspnea using nCPAP, bilevel PAP or auto CPAP is recommended. We treated 384 patients with nCPAP and 24% of the patients were added heated humidifier. Auto CPAP and bilevel PAP was administered in 10% and 6% of the patients indicated for PAP treatment, respectively.

Humans↗
PubMed2000

[Aggressive transformation and extramedullary tumor formation in IgA-lambda multiple myeloma].

A 52-year-old woman complained of lower back pain and gluteal pain in April 1997, and was found to have anemia, hypercalcemia and renal disorder. In September of the same year, she was diagnosed as having IgA-lambda myeloma (stage IIIA). VMMD-IFN therapy was started in November, 1997, and this resulted in improvement of the M-protein level, and relief of the pain in the lower back and gluteal region. A second course of VMMD-IFN therapy was also effective. In April 1998, however, the back pain worsened, and in July the patient suffered a fall and fractured her left femur. Upon readmission to our hospital, the level of M-protein was lower, and high fever, hypercalcemia, renal disorder, elevation of the LDH level, anemia and thrombocytopenia were observed. Bone marrow examination revealed 30% atypical large-sized CD19-, CD38+, CD56+ myeloma cells and chromosomal abnormalities. Although the symptoms were improved temporarily after a third course of VMMD therapy, disease aggravation occurred again, and extramedullary masses appeared on the head, face and pelvis. VAD therapy was performed without effect, and the patient died about 2 months after recurrence. This was a comparatively rare case of fulminant multiple myeloma occurring in the terminal stage.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Effects of dietary sulfur-containing amino acids on oxidative damage in rat liver caused by N-nitrosodimethylamine administration.

Effects of dietary protein and S-containing amino acids on oxidative damage were investigated in rat liver. After feeding rats for 3 weeks from weaning, lower GSH levels and higher metallothionein (MT) levels were found in the liver of rats fed on a 10% soyabean-protein-isolate (SPI)-based diet than those fed on a 10% casein-based diet. After injection of N-nitrosodimethylamine (NDMA) at 20 mg/kg body weight, increases in lipid peroxide, determined as thiobarbituric-acid reactive substances (TBARS), and gamma-glutamyltransferase (GGT) activity in the liver were observed in the 10% SPI diet group. By supplementing the 10% SPI diet with 0.3% cystine or methionine, GSH levels were increased, while MT levels were decreased, and elevation in TBARS levels after NDMA injection was diminished. On the other hand, increase in GGT activity could be prevented only by methionine supplement. On a 20% SPI or casein diet, TBARS concentration and GGT activity were not altered after NDMA injection with concomitant increase in GSH levels and decrease in MT levels. These results indicate that sufficient amounts of methionine and cystine in a diet are important to protect the liver from oxidative damage after NDMA administration, and GSH plays a primary role in the cellular protective function when compared with MT.

Alkylating Agents↗