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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 505 records · Page 28Linked to original sources
PubMed1997

Frequent loss of p16 expression and its correlation with clinicopathological parameters in pancreatic carcinoma.

Expression of the p16 gene product in human primary pancreatic carcinoma (PC) was investigated in paraffin-embedded tissue using a monoclonal antibody against p16 protein, clone G175-405, by means of immunohistochemistry, and the correlation of results with various clinicopathological parameters was evaluated. All six cases of normal pancreas and all but 1 of 20 cases of chronic pancreatitis expressed p16 protein, whereas 37.5% (3 of 8) of cystadenomas and 41. 9% (26 of 62) of PCs lost p16 expression. There was a significant difference between chronic pancreatitis and PC for frequency of the loss of p16 expression (P < 0.01). Moreover, loss of p16 expression in pancreatic malignancy was significantly associated with histological grade (G1 versus G2 and G3, P < 0.01) but not with sex, age, clinical stage, tumor location, or resectability. The survival period was shorter and metastasis is more likely in those cases that did not show p16 expression than those that did.

Adenocarcinoma↗
PubMed1996

Biochemical characterization and intracellular localization of the Menkes disease protein.

Menkes disease is a fatal neurodegenerative disorder of childhood due to the absence or dysfunction of a putative copper-transporting P-type ATPase encoded on the X chromosome. To elucidate the biosynthesis and subcellular localization of this protein, polyclonal antisera were generated against a bacterial fusion protein encoding the 4th to 6th copper-binding domains in the amino terminus of the human Menkes protein. RNA blot analysis revealed abundant Menkes gene expression in several cell lines, and immunoblotting studies utilizing this antiserum readily detected a 178-kDa protein in lysates from these cells. Pulse-chase studies indicate that this protein is synthesized as a single-chain polypeptide which is modified by N-linked glycosylation to a mature endoglycosidase H-resistant form. Sucrose gradient fractionation of HeLa cell lysates followed by immunoblotting of individual fractions with antibodies to proteins of known intracellular location identified the Menkes ATPase in fractions similar to those containing the cation-independent mannose-6-phosphate receptor. Consistent with this observation, confocal immunofluorescence studies of these same cells localized this protein to the trans-Golgi network and a vesicular compartment with no expression in the nucleus or on the plasma membrane. Taken together, these data provide a unique model of copper transport into the secretory pathway of mammalian cells which is compatible with clinical observations in affected patients and with recent data on homologous proteins identified in prokaryotes and yeast.

Adenosine Triphosphatases↗
PubMed1996

Myelin proteolipid protein (PLP), but not DM-20, is an inositol hexakisphosphate-binding protein.

Myelin proteolipid protein (PLP) and its alternatively spliced isoform, DM-20, are the major integral membrane proteins of central nervous system myelin. It is known that PLP and DM-20 are delivered to myelin by a finely regulated vesicular transport system in oligodendrocytes. Evolutionarily, it is believed that ancestral DM-20 acquired a PLP-specific exon to create PLP, after which PLP/DM-20 became a major component of central nervous system myelin. We purified PLP as an inositol 1,3,4,5-tetrakisphosphate-binding protein after solubilization in a non-organic solvent. However, under the isotonic condition, PLP binds inositol hexakisphosphate (InsP6) significantly, not inositol 1,3,4,5-tetrakisphosphate. Most of the InsP6-binding proteins are involved in vesicular transport, suggesting the involvement of PLP in vesicular transport. We separated DM-20 from PLP by CM-52 chromatography and showed that DM-20 has no InsP6 binding activity. These findings indicate that the PLP-specific domain confers the InsP6 binding activity and this interaction may be important for directing PLP transport to central nervous system myelin.

Animals↗
PubMed1996

Postoperative immunostimulation after complete resection improves survival of patients with stage I nonsmall cell lung carcinoma.

BACKGROUND: approximately 40% of primary lung carcinoma patients who die within 1 month after a complete resection have residual tumor in regional or distant organs, emphasizing the importance of postoperative adjuvant therapy. In this study, the effectiveness of transfer factor (TF) and nocardia rubra-cell wall skeleton (N-CWS) as adjuvant therapy for patients with primary, completely resected nonsmall cell carcinoma of the lung was evaluated in a randomized controlled trial METHODS: A total of 82 patients with Stage I disease who had a complete resection were allocated randomly into 2 groups: TF + N-CWS (n = 41) or control (surgery only) (n = 41). RESULTS: The distributions of age, sex, histology, differentiation, T classification, tumor size, visceral pleural invasion, and the site of origin, were similar in the two groups. The 5- and 10-year disease specific survival rates in the TF + N-CWS group were 85% and 85%, respectively, and those in the control group were 72% and 64%, respectively. There was a statistically significant difference between the two groups (P = 0.041). When the survival was analyzed according to clinical characteristics, significant differences were observed in patients with no visceral pleural invasion or with T1 disease. The frequency of distant metastasis was significantly less in the TF + N-CWS group than in the control group. CONCLUSIONS: These results indicate that TF + N-CWS is beneficial as adjuvant therapy after surgical treatment of Stage I nonsmall cell carcinoma of the lung.

Adjuvants, Immunologic↗
PubMed1996

Effects of ginsenosides on impaired performance caused by scopolamine in rats.

The effects of five structurally different ginsenosides on the performance impaired by scopolamine in rats were studied in a radial-arm maze. Ginsenoside Re had an ameliorating effect, but the ginsenosides, 20-O-glucosyl-protopanaxadiol, F2, Rf, and Rh1, did not. We reported previously that ginsenoside Rg1 had an ameliorating effect but that ginsenosides Rb1 and Rd did not (Yamaguchi et al., 1995, Psychoneuroendocrinology 20, 645). The sugar moieties at C(6) and C(20), which are possessed by Re and Rg1, seem to be indispensable for an ameliorating effect on the performance impaired by scopolamine.

Animals↗
PubMed1996

Adenosine 3',5'-cyclic monophosphate mimics the inhibitory effect of high glucose on MAP kinase phosphorylation in rat mesangial cells.

Alteration in mesangial cell function induced by high glucose levels is implicated in the development of diabetic nephropathy. The aim of this study was to investigate the mechanism by which high glucose attenuates mesangial cell proliferation. Thymidine incorporation in cultured mesangial cells decreased in the presence of high glucose concentrations in a dose dependent manner, with the maximum decrease of 25% occurring at a glucose concentration of 55.5 mM. Phosphorylation of mitogen-activated protein (MAP) kinase was abolished when the cells were treated with 55.5 mM glucose compared with 11.1 mM glucose. The concentration of intracellular cAMP doubled in the presence of 55.5 mM glucose. The addition of 8Br-cAMP (1.0 mM) to the culture media containing 11.1 mM glucose decreased thymidine incorporation by 34%, similar to the effect of high glucose. In order to clarify the contribution of protein kinase A (PKA) to the MAP kinase cascade, we used PKA inhibitor (H-8). The addition of H-8(10 microM) recovered MAP kinase phosphorylation in the presence of 55.5 mM glucose. Our data indicated that the inhibition of this mitogenic pathway mediated by activation of PKA, which is probably induced by high glucose levels, may play an important role in the perturbation of mesangial cells.

Animals↗
PubMed1996

Molecular identification of a putative human hyaluronan synthase.

To identify the putative mammalian hyaluronan synthase, we cloned a human cDNA that is related to the Streptococcus hyaluronan synthase (HasA) and the Xenopus developmental protein DG42 which has been shown to have chitin synthase activity. The cDNA, for which we propose the name Has2, encodes a novel protein with a predicted molecular mass of 63.6 kDa. Has2 shows 55% amino acid identity with Xenopus DG42 and 52% identity with the mouse HAS protein, another putative hyaluronan synthase recently reported by Itano and Kimata (Itano, N., and Kimata, K. (1996) J. Biol. Chem. 271, 9875-9878). The deduced primary structure revealed the presence of several hydrophobic stretches which can form multiple transmembrane domains. It also demonstrated the complete conservation of amino acid residues that are known to be critical for N-acetylglucosaminyltransferase activity of yeast chitin synthase. When the Has2 cDNA was transfected into human 293 and Chinese hamster ovary cells, the production of hyaluronan in the transfected cells increased up to 34- and 9-fold, respectively. Strong expression of Has2 mRNA was observed in exponentially proliferating human IMR-90 fibroblasts but not in growth-arrested IMR-90 cells. These results suggest that the Has2 protein is a crucial component of the human hyaluronan synthase system.

Amino Acid Sequence↗
PubMed1996

Down-regulation of telomerase activity is an early event in the differentiation of HL60 cells.

Telomerase has been shown to be essential for unlimited cell proliferation and has been linked to immortality. However, still very little is known about the mechanism by which this enzyme is activated or inactivated. To investigate its regulation, we closely monitored telomerase activity during HL60 cell differentiation induced by either 1 alpha,25-dihydroxyvitamin D3 or all-trans retinoic acid. To that effect, we used a new combination of TRAP assay and SPA, which provides reproducible data for the quantitation and detection of variations in enzyme activity. We thereby observed that the decrease in telomerase activity after induction of differentiation by either of these agents is an early event of the differentiation process rather than its consequence, and that it is independent of the growth arrest pathway. It is neither due to a reduced expression of its RNA component nor to the appearance of a telomerase inhibitor in differentiating cells but is parallel to an increase in p21 and Rb mRNA expression.

Base Sequence↗
PubMed1996

Relation of abnormal burst activity of spinal neurons to the recurrence of autotomy in rats.

Two groups of rats received different amounts of peripheral deafferentations; one group received sections of sciatic nerve (S-rats) and the other received sections of sciatic and saphenous nerves (SS-rats). In Experiment 1 the occurrence of autotomy was compared between S- and SS-rats for up to 70 days after the surgery. Autotomy in SS-rats frequently recurred until 40 days after denervation whereas in S-rats it scarcely recurred. In Experiment 2 spontaneous activity was recorded from the spinal cords in S- and SS-rats, and the proportion of burst firing cells (B-cells), characterized by periodic and high frequency bursts, was compared. In both S- and SS-rats with fresh wounds the occurrence of B-cells was high until 40 days after denervation. However, B-cells were still frequently observed in SS-rats with old wounds until 40 days after denervation, whereas B-cells were scarcely found in S-rats with similar old wounds. This finding corresponded well with the behavioral observation in Experiment 1. The data strongly suggests that the continuance of a high proportion of B-cells in the spinal cord plays an essential role for the induction of recurrent autotomy.

Afferent Pathways↗
PubMed1996

The primary gustatory area in human cerebral cortex studied by magnetoencephalography.

Magnetic fields (MFs) from gustatory stimulation with 1 M NaCl and 3 mM saccharin were recorded from the human brain by using a whole-cortex SQUID system. The averaged onset latency of MFs was 93 ms for NaCl and 172 ms for saccharin and no response was obtained for water. A high correlation coefficient was noted between the difference of onset MFs latencies in two tastants and that of behavioral reaction times, and responses to saccharin were delayed or abolished after treatment of a subject's tongue with a sweet-suppressing agent. This finding indicates that the MFs obtained were caused by gustatory stimulation. By plotting the estimated current dipole on the magnetic resonance image, we could locate the primary gustatory area at the transition area between the operculum and insula, as reported in macaque monkeys.

Adult↗
PubMed1996

Expression of vascular permeability factor/vascular endothelial growth factor in human hepatocellular carcinoma.

Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is unique in its ability to promote vascular permeability and endothelial cell growth, and its role in tumor development has received considerable attention. In this report, we describe the elevation of VPF/VEGF transcript expression in human hepatocellular carcinoma. Surgical samples of 23 patients with hepatocellular carcinoma were studied using reverse transcription-PCR analysis. The oligonucleotide primers were designed to amplify all four known splicing variants that could be expressed in the samples studied. Sixteen cases showed VPF/VEGF transcript expression in the tumor (16/23, 69.6%), whereas only 9 of the 23 patients showed it in the corresponding nontumoral part. There was no difference between the pattern of expression of VPF/VEGF isoforms in tumoral and nontumoral tissues. VPF/VEGF mRNA expression in the liver tumors was associated with fibrous capsule formation and septal formation (P < 0.05 respectively, Fisher's exact P test). In situ hybridization confirmed the presence of VPF/VEGF mRNA expression in tumor cells and less intensely in hepatocytes of nontumoral liver. We also found that VPF/VEGF expression in the tumor cell was increased in the area adjacent to necrotic regions (presumably hypoxic regions). As a regulator of vascular permeability and endothelial cell growth factor, VPF/VEGF may play an important role in the development of hepatocellular carcinoma.

Adult↗
PubMed1996

Selective mutations in cloned and expressed alpha-macroglobulin receptor binding fragment alter binding to either the alpha2-macroglobulin signaling receptor or the low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor.

alpha2-Macroglobulin (alpha2M) activated with methylamine binds to two distinct cell-surface receptors: low density-lipoprotein receptor-related protein/alpha2M receptors and alpha2M signaling receptors. Binding to lipoprotein receptor-related protein/alpha2M receptor but not alpha2M signal receptor is inhibitable by another ligand, receptor-associated protein. Direct binding studies with a recombinant receptor binding fragment (RBF) from rat alpha1M and murine macrophages demonstrate two classes of binding sites of apparent Kd = 90 pM (1500 sites/cell) and 40 nM (60,400 sites/cell). Receptor-associated protein competes with RBF for binding to the lower but not the higher affinity site. Site-directed mutation of Lys-1374 (human numbering) in RBF to Arg or Ile residues almost completely abolishes signal transduction as compared to wild-type RBF. Direct binding studies with K1374R demonstrated no significant alteration in binding to the lower affinity site; however, binding to the high affinity site is reduced by 83%. Mutation of Lys-1370 to Ala resulted in a 4-5-fold increase in the Kd for binding to the lower affinity site with no significant alteration in binding to the high affinity site or signal transduction properties. Studies demonstrate comparable internalization and degradation of wild-type RBF and K1374R; however, internalization and degradation of K1370A is negligible. These studies suggest that regions around Lys-1370 and Lys-1374 are involved in lipoprotein receptor-related protein/alpha2M receptor and alpha2M signaling receptor binding, respectively.

Amino Acid Sequence↗
PubMed1996

Adoptive immunotherapy with tumor-specific T lymphocytes generated from cytokine gene-modified tumor-primed lymph node cells.

Adoptive immunotherapy with immune T cells mediates regression of established tumors in animal models. We previously demonstrated that precursor lymphocytes of sensitized T cells can develop into mature effector cells after in vitro activation with anti-CD3 mAb and IL-2. We demonstrate here that tumor cells genetically modified to secrete IL-2 can enhance the precursor response in the tumor-bearing host and subsequently augment the antitumor efficacy of adoptive immunotherapy. MCA205 and MCA203, weakly immunogenic fibrosarcomas, were transfected in vitro with cDNA encoding for IL-2, IL-4, or IL-6. Lymph nodes (LN) draining these cytokine-producing tumors for 7 days were harvested, activated in vitro with anti-CD3/IL-2, and adoptively transferred into mice bearing established parental MCA205 pulmonary metastases. The effector cells generated from LN draining the IL-2 producing tumor exhibited enhanced antitumor activity compared with cells from LN draining parental, IL-4-producing, or IL-6-producing tumor. Phenotype analysis of cells from LN draining the IL-2-producing tumor revealed selective expansion of V beta 8+ cells. Depletion of V beta 8+ effector cells abrogated the antitumor efficacy indicating that V beta 8+ cells constituted the majority of antitumor reactivity and that secretion of IL-2 from tumor cells promoted the priming of V beta 8+ precursor cells, which can develop into mature effector cells. These results have important clinical implications that the method presented here could be applicable to the treatment of human cancer as more effective immunotherapy.

Animals↗
PubMed1996

Entire hemithorax irradiation following complete resection in patients with stage II-III invasive thymoma.

PURPOSE: To evaluate the feasibility and efficacy of prophylactic entire hemithorax irradiation (EH) in addition to mediastinal irradiation (MRT) following a complete resection in Stage II-III invasive thymoma. METHODS AND MATERIALS: Forty-three patients with invasive thymoma treated with surgery and radiation therapy between 1978 and 1993 were analyzed retrospectively. All 43 patients underwent a complete surgical resection and were judged to have Masaoka's Stage II-III invasive thymoma. Of these, 23 patients received EH and MRT (EH-MRT) and the remaining 20 received MRT. Of the 23 patients with EH-MRT, 11 were Stage II and 12 Stage III. Of the 20 with MRT, 11 were Stage II and 9 Stage III. In most cases, EH was 15 Gy per 15 fractions over 3 weeks (without lung compensation calculation). In both the EH-MRT and MRT group, the total radiation doses to the mediastinum were similar with a median of 40 Gy. The median follow-up time after surgery was 63 months and no patients were lost to follow-up. RESULTS: Only one of the 23 patients with EH-MRT relapsed. On the other hand, eight of the 20 with MRT relapsed, six of whom died of disease. The pleura was the most common site of failure. At 5 years, the relapse-free rate was 100% for those receiving EH-MRT and 66% for those with MRT (p = 0.03); the overall survival rate was 96% for those with EH-MRT, and 74% for those with MRT (p: not significant). The only significant treatment-related complication was radiation pneumonitis requiring treatment, in one patient who received MRT and three who received EH-MRT, including one death of a 72-year-old man and one 68-year-old woman with severe lung fibrosis. CONCLUSION: Except for elderly patients, EH-MRT following a macroscopically complete resection appears to be safe and feasible, and can reduce intrathoracic relapses.

Adult↗
PubMed1996

Neutrophil elastase inhibitor (ONO-5046) decreases cytokine-induced neutrophil chemoattractant after reperfusion of pancreaticoduodenal transplantation in rats.

The protective effects of a neutrophil elastase inhibitor (ONO-5046) on reperfusion injury following pancreaticoduodenal transplantation in rats were studied by measuring serum concentrations of cytokine-induced neutrophil chemoattractant (CINC). Male Wistar rats were transplanted with syngeneic pancreaticoduodenal grafts. ONO-5046 was injected intravenously 5 min before vascular clamping and immediately after reperfusion at a dose of 10 mg/kg. No significant differences were observed in the peak serum concentrations of amylase between the groups treated with and treated without ONO-5046. The serum lipase concentrations in the untreated animals increased and peaked 3 hr after reperfusion. ONO-5046 significantly decreased the peak serum lipase concentration. The serum CINC concentrations, which were determined by enzyme-linked immunosorbent assay, increased and peaked 3 hr after reperfusion, decreasing gradually thereafter. However, pretreatment with ONO-5046 significantly inhibited the rise in serum CINC concentrations after reperfusion. Expression of CICN transcripts in the pancrease grafts was evaluated by Northern blot analysis and peaked 3 hr after reperfusion in untreated animals. Pretreatment with ONO-5046 also significantly inhibited the expression of CINC mRNA transcripts in the graft. ONO-5046 significantly decreased the number of neutrophils accumulated in the pancreas graft 24 hr after transplantation. In vitro CINC production by peritoneal macrophages was increased by neutrophil elastase in dose-dependent fashion. However, ONO-5046 decreased CINC production by peritoneal macrophages in response to neutrophil elastase. These results suggest that ONO-5046 prevents early neutrophil accumulation in the pancreas following ischemia/reperfusion of pancreaticoduodenal transplantation.

Animals↗
PubMed1996

Induction of apoptosis reduces the severity of caerulein-induced pancreatitis in mice.

The recent observation that the severity of pancreatitis is inversely related to the extent of apoptosis in five experimental models of the disease has suggested the possibility that apoptosis might protect against pancreatic injury in pancreatitis. This hypothesis was tested by inducing pancreatitis in mice during a phase of extensive apoptosis. Mice were fed a raw soya diet for five weeks to stimulate pancreatic growth and then switched to a regular chow diet for 27 hrs to permit involution of the hypertrophied gland. That involution is characterized by extensive apoptosis of acinar cells. Pancreatitis was induced, in either control mice or mice undergoing pancreatic involution, by repeated intraperitoneal administration of a supramaximally stimulating dose of caerulein (50 microg/kg given each hr for 12 hrs). The magnitude of hyperamylasemia, degree of inflammation, and extent of necrosis were reduced in the mice receiving caerulein during pancreatic involution. We conclude that induction of apoptosis may protect against acinar cell injury and reduce the severity of pancreatitis.

Acute Disease↗
PubMed1996

Copurification of casein kinase II with transcription factor ATF/E4TF3.

We have developed a simple method to purify sequence-specific DNA-binding proteins directly from crude cell extracts by using DNA affinity latex beads. The method enabled us to purify not only DNA-binding proteins, but also their associated proteins. Using beads bearing the ATF/E4TF3 site from the adenovirus E4 gene promoter, a protein kinase activity was copurified with the ATF/E4TF3 family. We found that the kinase interacted with ATF1 in vitro efficiently. The kinase did not bind directly to DNA. The kinase mainly phosphorylated ATF1 on serine 36, which was one of target amino acids for casein kinase (CK) II. Biological features of the kinase were the same as those of CKII and an anti-CKII serum reacted with the kinase, indicating that the kinase was CKII. Moreover, it was clearly shown that one of CKII subunits, the CKII alpha protein bound to glutathione-S-transferase (GST) fusion ATF1 but not GST in vitro. It has been reported that a specific CKII inhibitor, 5,6-dichloro-1-beta-D-ribo-furanosylbenzimidazole (DRB) inhibits transcription by RNA polymerase II [Zandomeni et al., (1986) J. Biol. Chem. 261, 3414-3419]. Taken together, these results suggest that ATF/E4TF3 may recruit the CKII activity to a transcription initiation machinery and stimulate transcription.

Activating Transcription Factors↗