Search PubMed⌕ Search

Biomedical subjects

A Yamada

Publications and source records attributed to A Yamada.

At least 91 records · Page 5Linked to original sources
PubMed2000

Blocking the CD28-B7 T-cell costimulatory pathway abrogates the development of obliterative bronchiolitis in a murine heterotopic airway model.

BACKGROUND: CTLA4IgG that binds to B7 effectively inhibits the signaling of CD28/B7 pathway and induces antigen-specific T-cell unresponsiveness in vitro and in vivo. We examined whether the development of obliterative bronchiolitis in a murine heterotopic airway transplantation model is T cell dependent and whether CTLA4IgG abrogates the development of obliterative bronchiolitis. METHODS: Tracheae with main bronchi from C3H/He (H2k), BALB/C (H2d), or C57BL/6 (H2b) mice were transplanted heterotopically into subcutaneous pockets on the backs of BALB/C or BALB/C nu/nu mice on day 0. Recipient mice were untreated or intraperitoneally treated with either CTLA4IgG or human IgG with different time and dose schedules. RESULTS: The development of obliterative bronchiolitis, which leads to luminal obliteration by fibrous tissue in a murine heterotopic airway transplantation model, was T cell dependent and the development of obliterative bronchiolitis was significantly abrogated by the CTLA4IgG treatment. However, the normal ciliated columnar respiratory epithelial cells in allografts were lost and replaced by flattened attenuated epithelial cells even after the CTLA4IgG treatment. We further demonstrated that CTLA4IgG treatment did not result in the induction of donor-specific unresponsiveness. CONCLUSIONS: We demonstrated that the development of obliterative bronchiolitis in a murine heterotopic airway model involves both CD28/B7-dependent and -independent processes. The luminal obliteration by fibrous tissue is clearly CD28/B7 dependent and can be inhibited by CTLA4IgG. The luminal obliteration of allografted trachea by fibrous tissues and the loss of ciliated columnar respiratory epithelial cells represent distinct disease processes.

Abatacept↗
PubMed2000

Identification of a gene coding for a new squamous cell carcinoma antigen recognized by the CTL.

Peptide-based specific immunotherapy has resulted in tumor regression in some melanoma patients. However, tumor Ags and peptides for specific immunotherapy, except for treatment of melanomas, have not yet been well identified. In this study, we report a gene encoding a new squamous cell carcinoma (SCC) Ag recognized by cells of the HLA-A24-restricted and tumor-specific CTL line. This gene with 3958-bp length was transcribed from the chromosome 6q22 with six exons, and its mRNA was ubiquitously expressed in both SCCs and normal tissues, and partly expressed in adenocarcinomas. The deduced 958-aa sequence encoded by this gene showed no similarity to any known amino acid sequences. This gene product had a characteristic of an endoplasmic reticulum-resident protein. A 100-kDa protein was detected in the vast majority of SCCs from various tissues, in majority of renal cell carcinomas and brain tumors, and in about one-third of melanomas and adenocarcinomas from various organs other than the breast. In contrast, it was not expressed at all in any of the normal cells or tissues tested, including the testis and fetal liver. Three different peptides at positions 93-101, 161-169, and 899-907 of this Ag were recognized by this CTL line, and all of them induced HLA-A24-restricted and tumor-specific CTLs from PBMCs of SCC patients. Therefore, these peptides may be useful for peptide-based specific immunotherapy of HLA-A24+ patients with SCC in various organs, as well as for treatment of other cancer.

Amino Acid Sequence↗
PubMed2000

Chloramine-T in radiolabeling techniques. III. Radioiodination of biomolecules containing thioether groups.

A previously reported method for iodination of the tyrosine moiety of oxidation-sensitive biomolecules was found to cause unacceptable damage to biomolecules containing thiols and thioether groups. This was due to the oxidation of the sulfur-containing residues by molecular iodine (I(2)). To selectively iodinate the tyrosine moiety with minimum oxidation to the sulfur functionality, studies of the kinetics of the reactions between I-(3) and various amino acids and small peptides at various pH values in phosphate buffer were undertaken. Within the pH range studied (5.5-8.2), the results showed that the iodination reaction is strongly catalyzed by hydroxide ions, whereas the oxidation of the sulfur group was insensitive to pH. The results also showed that both reactions are strongly catalyzed by HPO-(4) ion. In a complex molecule, such as methionine-enkephalin, oxidation of the methionine residue (undesirable reaction) proceeds in parallel with iodination of the tyrosine residue (desirable reaction). If such a molecule was iodinated in 0.01 M phosphate buffer at pH values above 7.5, the iodination reaction would proceed much more rapidly than the oxidation reaction, resulting in a high yield of iodinated substrate with little oxidative damage.

Chloramines↗
PubMed2000

Catchin, a novel protein in molluscan catch muscles, is produced by alternative splicing from the myosin heavy chain gene.

Molluscan catch muscles contain polypeptides of 110-120 kDa in size which have the same partial amino acid sequences as those of the myosin heavy chain (MHC). Here we provide evidence that these polypeptides are major components only of the catch-type muscles (their estimated molar ratio to MHC is approximately 1:1) and they are alternative products of the MHC gene. Northern blot analysis of total RNA from Mytilus galloprovincialis catch muscles was carried out with fragments from the 3'-end of the MHC cDNA as probes. We detected two bands of 6.5 kb and 3.5 kb. The former corresponds to the MHC mRNA, and the latter is an mRNA coding for catchin, a novel myosin rod-like protein. By using a 5'-rapid amplification of cDNA ends (RACE) PCR method, the full-length cDNA of Mytilus catchin was cloned. It codes for a protein with a unique N-terminal domain of 156 residues (rich in serine, threonine, and proline), which includes a phosphorylatable peptide sequence. The rest of the sequence is identical with the C-terminal 830 residues of the MHC. We also analyzed Mytilus and scallop (Argopecten irradians) genomic DNAs and found that the 5'-end of the cDNA sequence was located in a large intron of the MHC gene in both species. Since catchin is abundantly expressed only in catch muscles and it is phosphorylatable, we suggest that it may play an important role in the catch contraction of molluscan smooth muscles.

Alternative Splicing↗
PubMed2000

Cell density-dependent regulation of proteoglycan synthesis by transforming growth factor-beta(1) in cultured bovine aortic endothelial cells.

The regulation of vascular endothelial cell behavior during angiogenesis and in disease by transforming growth factor-beta(1) (TGF-beta(1)) is complex, but it clearly involves growth factor-induced changes in extracellular matrix synthesis. Proteoglycans (PGs) synthesized by endothelial cells contribute to the formation of the vascular extracellular matrix and also influence cellular proliferation and migration. Since the effects of TGF-beta(1) on vascular smooth muscle cell growth are dependent on cell density, it is possible that TGF-beta(1) also directs different patterns of PG synthesis in endothelial cells at different cell densities. In the present study, dense and sparse cultures of bovine aortic endothelial cells were metabolically labeled with [(3)H]glucosamine, [(35)S]sulfate, or (35)S-labeled amino acids in the presence of TGF-beta(1). The labeled PGs were characterized by DEAE-Sephacel ion exchange chromatography and Sepharose CL-4B molecular sieve chromatography. The glycosaminoglycan M(r) and composition were analyzed by Sepharose CL-6B chromatography, and the core protein M(r) was analyzed by SDS-polyacrylamide gel electrophoresis, before and after digestion with papain, heparitinase, or chondroitin ABC lyase. These experiments indicate that the effect of TGF-beta(1) on vascular endothelial cell PG synthesis is dependent on cell density. Specifically, TGF-beta(1) induced an accumulation of small chondroitin/dermatan sulfate PGs (CS/DSPGs) with core proteins of approximately 50 kDa in the medium of both dense and sparse cultures, but a cell layer-associated heparan sulfate PG with a core protein size of approximately 400 kDa accumulated only in dense cultures. Moreover, only in the dense cell cultures did TGF-beta(1) cause CS/DSPG hydrodynamic size to increase, which was due to the synthesis of CS/DSPGs with longer glycosaminoglycan chains. The heparan sulfate PG and CS/DSPG core proteins were identified as perlecan and biglycan, respectively, by Western blot analysis. The present data suggest that TGF-beta(1) promotes the synthesis of both perlecan and biglycan when endothelial cell density is high, whereas only biglycan synthesis is stimulated when the cell density is low. Furthermore, glycosaminoglycan chains are elongated only in biglycan synthesized by the cells at a high cell density.

Amino Acids↗
PubMed2000

The fungal metabolite gliotoxin: immunosuppressive activity on CTL-mediated cytotoxicity.

Gliotoxin, a potential etiologic agent which is synthesized by Aspergillus fumigatus and other pathogenic fungi, exhibits a variety of immunosuppressive activities. We have found that gliotoxin markedly inhibits both perforin-dependent and Fas ligand-dependent cytotoxic T-lymphocyte (CTL)-mediated cytotoxicity. Gliotoxin blocked granule exocytosis and the production of inositol phosphates in response to anti-CD3 stimulation. Apparently, activation signals were not efficiently received by the gliotoxin-treated CTL clone, perhaps because gliotoxin profoundly disturbed CTL cell attachment to immobilized anti-CD3. Although the expression of surface molecules of the CTL clone such as CD3 was unaffected by gliotoxin, the effector/target conjugate formation was inhibited dose-dependently by gliotoxin treatment of the effector CTL clone. These results suggest that gliotoxin prevents CTL from interacting with target cells.

Animals↗
PubMed2000

Genetic dissection of vasculitis in MRL/lpr lupus mice: a novel susceptibility locus involving the CD72c allele.

An MRL/MpJ strain of mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), composed of genomes derived from LG/J, AKR/J, C3H/Di and C57BL/6J mice, develops systemic vasculitis coincidentally with other collagen diseases, but a C3H/HeJ-lpr/lpr (C3H/lpr) strain does not. In a genome-wide screening of the MRL background genes mediating susceptibility to collagen diseases using N2 progeny mice MRL/lpr x (MRL/lpr x C3H/lpr)F1, we previously found that each collagen disease is controlled by a different set of genes. To clarify the candidate genes for vasculitis, we extended the linkage analysis of renal vasculitis to a larger number of N2 mice and to F2 intercross mice. Two distinct recessive susceptibility loci for vasculitis were mapped on chromosome (Chr) 4 at D4Mit89 and D4Mit147 in both progenies. The former was a novel locus for lupus phenotypes, which involved the MRL allele CD72(c) in contrast to the C3H allele CD72(b). The one on Chr 3 was a recessive locus which had an inhibitory effect on vasculitis. From their composition these loci seemed to be derived from AKR/J (for one) and LG/J (for another two) strains, and appeared to act in an additive manner on the development of vasculitis, indicating that vasculitis in MRL/lpr mice is inherited in a polygenic manner.

Alleles↗
PubMed2000

Serum MAGE-4 protein in ovarian cancer patients.

OBJECTIVE: We measured serum levels of MAGE-4 protein in patients with ovarian cancer to investigate the relationship between serum MAGE-4 positivity and prognosis. METHODS: Serum levels of MAGE-4 protein were measured with an ELISA system. RESULTS: Serum levels of MAGE-4 in patients with ovarian cancer were significantly higher than levels in patients with benign diseases. Serum MAGE-4 protein was considered positive in 22% of primary ovarian cancer patients. The positive rate was the highest in sera of patients with surface epithelial-stromal tumors, particularly serous adenocarcinomas (24%). The survival time after a primary surgical operation in ovarian cancer patients with serum MAGE-4 positivity was significantly shorter than that of MAGE-4-negative cases. CONCLUSION: These results suggest that serum MAGE-4 protein is a potential prognostic factor of reduced survival in ovarian cancer patients.

Adult↗
PubMed2000

ONO-4817, an orally active matrix metalloproteinase inhibitor, prevents lipopolysaccharide-induced proteoglycan release from the joint cartilage in guinea pigs.

OBJECTIVE AND DESIGN: To evaluate the effect of a newly developed inhibitor of matrix metalloproteinases (MMPs), ONO-4817, on the degradation of cartilage in the guinea pig arthritis model. MATERIALS: 42 guinea pigs were used in the arthritis model. TREATMENT: Lipopolysaccharide (LPS) was injected into guinea pig knee joints. The content of proteoglycan released in synovial cavity was measured as a marker of cartilage degradation. ONO-4817, dexamethasone or indomethacin were administered orally to the animals. RESULTS: ONO-4817 showed a broad inhibitory activity against MMPs except MMP-1 and MMP-7. The oral administration of ONO-4817 dose-dependently suppressed the release of proteoglycan from the cartilage of the knee joints. CONCLUSION: This study suggests the possibility that a novel MMP inhibitor, ONO-4817 may have a therapeutic utility for MMP-related diseases.

Animals↗
PubMed2000

Production of eicosapentaenoic acid by a recombinant marine cyanobacterium, Synechococcus sp.

The eicosapentaenoic acid (EPA) synthesis gene cluster from an EPA-producing bacterium, Shewanella sp. SCRC-2738, was cloned into a broad-host range vector, pJRD215, and then introduced into a marine cyanobacterium, Synechococcus sp. NKBG15041c, by conjugation. The transconjugant cyanobacteria produced 3.7 +/- 0.2% (2.24 +/- 0.13 mg/L) EPA (n-3) and 2.5 +/- 0.2% (1.49 +/- 0.06 mg/L) eicosatetraenoic acid (n-3) of the total fatty acids when the cells were cultured at 23 degrees C at a light intensity of 1,000-1,500 Lux. The EPA and eico-satetraenoic acid contents of the cells were increased to 4.6 +/- 0.6% (3.86 +/- 1.11 mg/L) and 4.7 +/- 0.3% (3.86 +/- 0.82 mg/L), and 7.5 +/- 0.3% (1.76 +/- 0.10 mg/L) and 5.1 +/- 0.2% (1.19 +/- 0.06 mg/L) when they were cultured at low temperature (18 degrees C) and at lower light intensity (40 Lux), respectively.

Alteromonas↗
PubMed2000

Comparative single-molecule and ensemble myosin enzymology: sulfoindocyanine ATP and ADP derivatives.

Single-molecule and macroscopic reactions of fluorescent nucleotides with myosin have been compared. The single-molecule studies serve as paradigms for enzyme-catalyzed reactions and ligand-receptor interactions analyzed as individual stochastic processes. Fluorescent nucleotides, called Cy3-EDA-ATP and Cy5-EDA-ATP, were derived by coupling the dyes Cy3.29.OH and Cy5.29.OH (compounds XI and XIV, respectively, in, Bioconjug. Chem. 4:105-111)) with 2'(3')-O-[N-(2-aminoethyl)carbamoyl]ATP (EDA-ATP). The ATP(ADP) analogs were separated into their respective 2'- and 3'-O-isomers, the interconversion rate of which was 30[OH(-)] s(-1) (0.016 h(-1) at pH 7.1) at 22 degrees C. Macroscopic studies showed that 2'(3')-O-substituted nucleotides had properties similar to those of ATP and ADP in their interactions with myosin, actomyosin, and muscle fibers, although the ATP analogs did not relax muscle as well as ATP did. Significant differences in the fluorescence intensity of Cy3-nucleotide 2'- and 3'-O-isomers in free solution and when they interacted with myosin were evident. Single-molecule studies using total internal reflection fluorescence microscopy showed that reciprocal mean lifetimes of the nucleotide analogs interacting with myosin filaments were one- to severalfold greater than predicted from macroscopic data. Kinetic and equilibrium data of nucleotide-(acto)myosin interactions derived from single-molecule microscopy now have a biochemical and physiological framework. This is important for single-molecule mechanical studies of motor proteins.

Actins↗
PubMed2000

Chlorella vulgaris culture supernatant (CVS) reduces psychological stress-induced apoptosis in thymocytes of mice.

A glycoprotein prepared from Chlorella vulgaris culture supernatant (CVS) is a biological response modifier (BRM) which exhibits protective activities against tumor metastasis and 5-fluorouracil-induced immunosuppression. We here show that oral administration of CVS prevented significantly the apoptosis of thymocytes in mice undergoing psychological stress in a communication box. Mice were exposed to the emotional stress for 14 days by witnessing other mice being exposed to foot-shock. The numbers in thymocytes, especially CD4(+)CD8(+) population, were decreased significantly and apoptotic cells, as assessed by Annexin V expression, were reciprocally increased after the exposure to the psychological stress. C. vulgaris culture supernatant (CVS) administration significantly suppressed the increase in serum corticosterone level in the psychologically stressed mice. These results suggest that CVS prevents psychological stress and maintain homeostasis in the face of external environmental changes.

Animals↗
PubMed2000

Severe ectopic calcification of the intestinal wall in a patient on long-term continuous ambulatory peritoneal dialysis therapy.

We report autopsy findings of a 69-year-old man on long-term CAPD therapy for 13 years who showed linear peritoneal calcification. Continuous ambulatory peritoneal dialysis (CAPD) was started in 1982. He has been administered excessive amounts of vitamin D(3) derivatives (VitD) (2.0 to 2.5 microg daily) and calcium carbonate (4 g daily) for secondary hyperparathyroidism since initiation of CAPD. In May 1995, his intact parathyroid hormone (PTH) level increased over 1,000 pg/mL. Immediately after VitD was changed from pill to liquid, the dose was increased to 5 microg daily. Although the serum calcium level remained between 4.5 and 4.9 mEq/L, and serum phosphate level was 5.0 to 7.2 mg/dL, plain abdominal radiography and computed tomography showed continuous calcification along the intestinal wall in October 1995. In spite of the continuation of CAPD therapy, he remained asymptomatic until he died of congestive heart failure in January 1997. He experienced eight episodes of peritonitis during his clinical course. Autopsy showed that numerous calcified plaques were present on the submucosal portion between the thickened serosa and the longitudinal layer of the muscularis externa. The remainder of the subserosa was fibrotic, and the small arteries had markedly thickened intima and severely narrowed lumina.

Abdominal Muscles↗
PubMed2000

Splenectomy may improve the glomerulopathy of type II mixed cryoglobulinemia.

Many patients with type II mixed cryoglobulinemia have been shown to be infected with hapatitis C virus (HCV). Therefore, interferon-alfa has become the first choice of treatment for patients with HCV-associated cryoglobulinemia. However, the disease often relapses after the discontinuation of interferon therapy. The long-term effect of interferon therapy is controversial. Therefore, a more effective therapy needs to be developed. A 62-year-old Japanese woman was admitted to our hospital for the examination of abnormal liver function tests, severe edema, and purpura in her lower extremities. Glomerulopathy secondary to HCV-related cryoglobulinemia was suspected. Her serum creatinine was increased to 2.1 mg/dL. Interferon therapy was considered initially. However, because of pancytopenia caused by liver cirrhosis and splenomegaly, splenectomy was performed in February 1997, before the start of interferon therapy. Renal biopsy specimen taken at the time of the splenectomy showed typical cryoglobulinemic glomerulonephritis. Gradually, after surgery, the patient's thrombocytopenia and anemia improved, her proteinuria and hematuria were decreased, her cryocrit dropped from 15% to 5%, the Ccr increased from 21.1 mL/min to 48.8 mL/min, and the purpura in her lower extremities disappeared. A repeat renal biopsy performed in May 1998 showed marked histological improvement. Splenectomy is not widely accepted as a treatment for cryoglobulinemia. Our case suggests the possibility that the monoclonal-IgM component of the type II cryoglobulin may be formed in the spleen. In conclusion, splenectomy may be an effective therapy for cryoglobulinemia in patients with HCV-positive liver cirrhosis and pancytopenia secondary to splenomegaly.

Anemia↗
PubMed2000

A unique monoclonal antibody mNI-11 rapidly enhances spread formation in human umbilical vein endothelial cells.

We previously reported a novel monoclonal antibody (MAb), designated mNI-11, recognizing an adhesion-associated antigen distinct from any previously reported ones. In this article, this adhesion-associated antigen with a molecular weight of about 97 kDa was found to be strongly expressed on human umbilical vein endothelial cells (HUVECs) by fluorescence-activated cell sorter (FACS) analysis. Expression of this antigen on HUVECs was slightly increased in response to the exposure to tumor necrosis factor-alpha (TNF-alpha) or phorbol myristate acetate (PMA). As a biological function exerted by this antigen, it was of great interest that immobilized mNI-11 directly and rapidly enhanced the spread formation of HUVECs, whereas MAbs binding other adhesion-associated antigens such as mNI-58A (anti-CD11a), L130 (anti-CD18), L133.1 (anti-CD31), L178 (anti-CD44), L25.3 (anti-CD49d), or LB-2 (anti-CD54) did not carry such activity under the same conditions. The HUVECs spread formation enhanced by mNI-11 was completely blocked in the presence of a microfilament formation inhibitor, cytochalasin D (CyD), a Ca2+ calmodulin inhibitor, W-7, EDTA, and was partially blocked by a microtubule formation inhibitor, nocodazole, a protein kinase C (PKC) inhibitor, H-7, and a protein synthesis inhibitor, cycloheximide (CHX). However, a protein tyrosine kinase (PTK) inhibitor, genistein, did not affect the spread formation under the same conditions. Taken together, it was suggested that the spread formation of HUVECs enhanced by mNI-11 was mainly associated with the influx of Ca2+ and microfilament reorganization. In addition, the novel property associated with mNI-11 to enhance the spread formation of HUVECs was possibly mediated through its reaction against a unique epitope on HUVECs.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2000

A microfilament formation inhibitor, cytochalasin strongly enhances the low-affinity Fc epsilon receptor II (CD23) expression on the human monocyte-like cell line, U937.

Enhancement of the low-affinity Fc epsilon receptor (CD23) expression by cytochalasin was analyzed on the human monocytelike cell line, U937. The CD23 expression on the U937 cells was enhanced at 24 hr after culture with cytochalasin B, D, or E, especially cytochalasin E having the most remarkable effect on it at the low concentration. This enhanced expression was found to be associated with a concomitant increase of a CD23 (about 45-kDa) protein on the U937 cells as assessed by Western blotting analysis. On the other hand, CD11a, CD18, CD31, CD49d, or CD54 was not markedly enhanced on the U937 cells by culture with cytochalasin E, although the mean fluorescence intensities (MFIs) of CD11a, CD18, and CD54 on U937 was partially up-regulated. Cell growth of U937 cultured with cytochalasin E was completely suppressed for 72 hr, but cell viability was sufficiently maintained (more than 95%). Soluble-formed CD23 (sCD23) also was released from the U937 cells at 24 to 72 hr after culture with cytochalasin E. In addition, the protein tyrosine kinase activity was detected in the U937 cells cultured with cytochalasin E for 24 hr using the enzyme immunoassay. Enhancement of the CD23 expression on the U937 cells at 24 to 72 hr cultured with cytochalasin E was sufficiently blocked by protein tyrosine kinase inhibitors herbimycin A and genistein, and a protein synthesis inhibitor, cychloheximide. On the other hand, protein kinase C inhibitors such as H-7 and H-8 had no effect on this CD23 expression. These results suggest that a mechanism underlying enhancement of the CD23 expression on the U937 cells cultured with cytochalasin E is mediated through tyrosine phosphorylation and protein synthesis.

Actin Cytoskeleton↗
PubMed2000

CDw108 expression during T-cell development.

We recently reported a gene encoding the human CDw108, a glycosylphosphatidylinositol (GPI)-anchored membrane glycoprotein that is preferentially expressed on activated T lymphocytes and erythrocytes. The present study investigated the expression of CDw108 on various tissues and cells, particularly on T cells during development. The murine CDw108 cDNA was cloned initially, and it was highly homologous to the human CDw108 (88.0% or 89.3% similarity at the nucleotide or amino acid level, respectively) or identical to the murine semaphorin K1/Sema7A. The CDw108 mRNA was demonstrated in a few tissues including thymus and brain with the highest expression coming on day 7 in whole embryo followed by relatively consistent expression during development. Cell-surface expression of the CDw108 during T-cell development was further examined by flow cytometry in the human umbilical cord blood and thymus. It was preferentially expressed on a CD34+ stem cell population of umbilical cord blood, and CD3dull CD34+/- CD117 (c-kit)+ CD4bright CDbright cells in the thymus that are involved in the stage of positive selection. These results suggest the contribution of CDw108 in T-cell development, especially in the stage of positive selection in the thymus.

Age Factors↗