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Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

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

Myosin light chain kinase mediates sarcomere organization during cardiac hypertrophy in vitro.

During the development of hypertrophy, cardiac myocytes increase organization of the sarcomere, a highly ordered contractile unit in striated muscle cells. Several hypertrophic agonists, such as angiotensin II, phenylephrine, and endothelin-1, have been shown to promote the sarcomere organization. However, the signaling pathway, which links extracellular stimuli to sarcomere organization, has not been clearly demonstrated. Here, we demonstrate that myosin light chain kinase specifically mediates agonist-induced sarcomere organization during early hypertrophic response. Acute administration of a hypertrophic agonist, phenylephrine, or angiotensin II, causes phosphorylation of myosin light chain 2v both in cultured cardiac myocytes and in the adult heart in vivo. We also show that both sarcomere organization and myosin light chain 2v phosphorylation are dependent on the activation of Ca2+/calmodulin pathway, a known activator of myosin light chain kinase. These results define a new and specific role of myosin light chain kinase in cardiac myocytes, which may provide a rapid adaptive mechanism in response to hypertrophic stimuli.

Angiotensin II↗
PubMed2000

Esophageal hemangioma successfully treated by fulguration using potassium titanyl phosphate/yttrium aluminum garnet (KTP/YAG) laser: a case report.

Esophageal hemangioma is an extremely rare tumor. We report a case of a 39-year-old man who was found to have an hemangioma which extended from the hypopharynx to the upper thoracic esophagus revealed by endoscopic examination. Computed tomography (CT) images, magnetic resonance imaging (MRI) and angiography were useful in the diagnosis. He was successfully treated by fulguration using potassium titanyl phosphate/yttrium aluminum garnet (KTP/YAG laser) four times and no recurrence has been seen. This patient has since been followed up carefully and additional fulguration will be performed if necessary. KTP/YAG laser is useful for the treatment of a large hemangioma as a less invasive method.

Adult↗
PubMed2000

Hepatitis C virus core protein activates the MAPK/ERK cascade synergistically with tumor promoter TPA, but not with epidermal growth factor or transforming growth factor alpha.

Persistent hepatitis C virus (HCV) infection is associated with the development of human hepatocellular carcinoma (HCC), although the mechanism of HCV-related hepatocarcinogenesis remains unclear. Recently, however, the close relationships between the development of HCC and the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) cascade have been described. In the present study, we investigated the effects of HCV core protein on this MAPK/ERK cascade. HCV core protein significantly activated the MAPK/ERK cascade, including Elk1. We also examined whether HCV core protein acted synergistically along with hepatocyte mitogen-mediated MAPK/ERK activation. Interestingly, Elk-1 activities were further enhanced by the tumor promoter, 12-O-tetradecanoyl phorbol 13-acetate (TPA), but not by hepatocyte mitogens (epidermal growth factor [EGF] and transforming growth factor alpha [TGF-alpha]) in NIH3T3 cells and HepG2 cells expressing HCV core protein. Moreover, the MAPK/ERK activation by HCV core protein was blocked in the presence of the specific MEK1 inhibitor, PD98059. These results indicate that ERK activation by HCV core protein may be independent of hepatocyte mitogen-mediated signaling but synergistic with TPA, and HCV core protein may function at MEK1 or farther upstream of that component.

3T3 Cells↗
PubMed2000

Human homologue of maid: A dominant inhibitory helix-loop-helix protein associated with liver-specific gene expression.

The helix-loop-helix (HLH) family of transcriptional regulatory proteins are key regulators in numerous developmental processes. The class I HLH proteins, such as E12 are ubiquitously expressed. Class II HLH proteins, such as MyoD, are expressed in a tissue-specific manner. Class I and II heterodimers can bind to E-boxes (CANNTG) and regulate lineage commitments of embryonic cells. In an attempt to identify partners for the E12 protein that may exert control during liver development, we performed the yeast 2-hybrid screen using an expression complementary DNA library from human fetal liver. A novel dominant inhibitory HLH factor, designated HHM (human homologue of maid), was isolated and characterized. HHM is structurally related to the Id family and was highly expressed in brain, pituitary gland, lung, heart, placenta, fetal liver, and bone marrow. HHM physically interacted with E12 in vitro and in mammalian cells. Comparison of the dominant inhibitory effects of HHM and Id2 on the binding of E12/MyoD dimer to an E-box element revealed a weaker inhibition by HHM. However, HHM but not Id2 specifically inhibited the luciferase gene activation induced by hepatic nuclear factor 4 (HNF4) promoter. The HHM was transiently expressed during stem-cell-driven regeneration of the liver at the stage in which the early basophilic foci of hepatocytes started to appear. These results suggest that HHM is a novel type of dominant inhibitory HLH protein that might modulate liver-specific gene expression.

Amino Acid Sequence↗
PubMed2000

Three new lanostane-type triterpene lactones from the stem bark of Abies mariesii.

Three new delta 8-lanostane-type triterpene lactones (1), (2) and (3) were isolated from the stem bark of Abies mariesii M. and unambiguously characterized on the basis of spectroscopic and chemical evidence. Chemical modification of compound 1 showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA).

Antineoplastic Agents, Phytogenic↗
PubMed2000

WAF1 accumulation by carbon-ion beam and alpha-particle irradiation in human glioblastoma cultured cells.

PURPOSE: There have been no reports about the effects of heavy-ion beams on the expression of the WAF1 gene, although ionizing radiation such as y-rays and X-rays is well known to induce WAF1 (p21/CIP1/sdi1) gene expression in a p53-dependent manner. In the present study, it was examined whether WAF1 accumulation was induced after carbon-ion (C-) beam or alpha-particle irradiation in four glioblastoma cell lines. MATERIALS AND METHODS: A colony assay for radiosensitivity and Western blot analysis of WAF1 were applied to two human glioblastoma cell lines, A-172 bearing wild-type p53 (wtp53) and T98G bearing mutated p53 (mp53). A-172/neo and A-172/mp53 were transfected with a control vector (containing only a neo selection marker) and a mp53 expression vector respectively. RESULTS: The amount of WAF1 increased markedly after X-ray irradiation in A-172 and A-172/neo cells but not in T98G and A-172/mp53 cells. The level of WAF1 reached a plateau at 3-10 h after X-ray irradiation at 5 Gy in A-172 and A-172/neo cells. Likewise, the levels of WAF1 in A-172 and A-172/neo cells reached a plateau at 3-10 h and 6-24 h after C-beam (3.0 Gy) and alpha-particle (4.5 Gy) irradiation respectively. The amount of WAF1 increased markedly in a dose-dependent manner 10 h after X-ray, C-beam or alpha-particle irradiation in A-172 and A-172/neo cells but not in T98G or A-172/mp53 cells. In addition, cell survival assay showed that these cell lines were most sensitive to C-beams, less sensitive to alpha-particles and least sensitive to X-rays at 10% survival. There was no difference in sensitivity among these cell lines against C-beam and alpha-particle irradiation whereas wtp53 cells (A-172 and A-172/neo) were more sensitive to X-rays than mp53 cells (A-172/mp53 and T98G). CONCLUSIONS: These results indicate that C-beams and alpha-particles induce p53-dependent WAF1 accumulation as well as is the case with X-rays, suggesting that WAF1 protein accumulation may not contribute to cell killing.

Alpha Particles↗
PubMed2000

Sevoflurane does not inhibit human platelet aggregation induced by thrombin.

BACKGROUND: Sevoflurane reportedly inhibits adenosine diphosphate-induced platelet aggregation by suppressing thromboxane A2 formation. The increase in intracellular calcium concentration that fosters platelet aggregation, however, is also induced by other cell signaling pathways, such as activation of the production of inositol 1,4,5-triphosphate by thrombin. The current study aimed to clarify the net influence of sevoflurane on thrombin-induced platelet aggregation. METHODS: Washed platelets were stimulated by thrombin after incubation with 0.5, 1.0, or 1.5 mM sevoflurane, halothane, or isoflurane. Aggregation curves were measured by an aggregometer. Intracellular calcium concentration was measured fluorometrically using fura-2. Calcium mobilization via plasma membrane calcium channels and the dense tubular system was assessed differentially. Intracellular inositol 1,4,5-triphosphate was measured by radioimmunoassay. RESULTS: Halothane significantly suppressed aggregation ratios at 5 min compared with those in controls (89 +/- 7%) to 71 +/- 10% (1.0 mM) and 60 +/- 11% (1.5 mM) and the increase in intracellular calcium concentration (controls, 821 +/- 95 nM vs. 440 +/- 124 nM [1.0 mM] or 410 +/- 74 nM [1.5 mM]). Halothane also significantly inhibited release of calcium from the dense tubular system (controls, 220 +/- 48 nM vs. 142 +/- 31 nM [1.0 mM]). Neither sevoflurane nor isoflurane produced a net change in aggregation ratios, intracellular calcium concentration, or calcium mobilization. Halothane (1 mM) significantly suppressed inositol 1,4,5-triphosphate concentrations, whereas neither 1 mM isoflurane nor 1 mM sevoflurane had any effect. CONCLUSIONS: Although sevoflurane has been reported to inhibit human platelet aggregation induced by weak agonists such as adenosine diphosphate, it does not inhibit human platelet aggregation induced by strong agonists such as thrombin.

Anesthetics, Inhalation↗
PubMed2000

Scaling behaviors of branched polymers

We study the thermodynamic behavior of branched polymers. We first study random walks in order to clarify the thermodynamic relation between the canonical ensemble and the grand canonical ensemble. We then show that correlation functions for branched polymers are given by those for straight phi(3) theory with a single mass insertion, not those for the straight phi(3) theory themselves. In particular, the two-point function behaves as 1/p(4), not as 1/p(2), in the scaling region. This behavior is consistent with the fact that the Hausdorff dimension of the branched polymer is 4. In the appendixes we derive the exact two-point correlation function at finite (but large) system size N, which is consistent with the analysis in the body of the paper.

Journal Article↗
PubMed2000

Hepatitis C virus core protein interacts with 14-3-3 protein and activates the kinase Raf-1.

Persistent hepatitis C virus (HCV) infection is a major cause of chronic liver dysfunction in humans and is epidemiologically closely associated with the development of human hepatocellular carcinoma. Among HCV components, core protein has been reported to be implicated in cell growth regulation both in vitro and in vivo, although mechanisms explaining those effects are still unclear. In the present study, we identified that members of the 14-3-3 protein family associate with HCV core protein. 14-3-3 protein bound to HCV core protein in a phosphoserine-dependent manner. Introduction of HCV core protein caused a substantial increase in Raf-1 kinase activity in HepG2 cells and in a yeast genetic assay. Furthermore, the HCV core-14-3-3 interaction was essential for Raf-1 kinase activation by HCV core protein. These results suggest that HCV core protein may represent a novel type of Raf-1 kinase-activating protein through its interaction with 14-3-3 protein and may contribute to hepatocyte growth regulation.

14-3-3 Proteins↗
PubMed2000

Analysis of prognostic and survival factors related to treatment of low-grade astrocytomas in adults.

Prognostic factors for low-grade astrocytomas have been proposed, but optimal treatment remains controversial. Eighty-eight consecutive adult patients with supratentorial low-grade astrocytomas were retrospectively reviewed to determine specific factors influencing outcome. All underwent craniotomy (43 radical resections, 45 nonradical resections). Sex, age at diagnosis, preoperative Karnofsky performance status (KPS), tumor location, estimated extent of resection, radiation, chemotherapy, histological type, p53 status, MIB-1 staining and the apoptotic index were assessed as parameters for prognostic significance. KPS (p = 0.03), tumor location (p < 0.001), extent of surgical resection (p < 0.001) and radiotherapy (p = 0.01) were significantly associated with longer survival rates by univariate analysis. Multivariate analysis also showed a significant correlation between radiation therapy after surgical removal and survival time (p < 0.001). p53 status was not of importance in determining the necessity for radiotherapy. Radical surgical removal is the most important factor in the management of low-grade astrocytomas. Radiation therapy appears to be effective in improving the prognosis regardless of the extent of surgical resection or the p53 status.

Adult↗
PubMed2000

Peptide bond synthesis: function of the efp gene product.

The efp gene encodes a protein that is essential for the growth and for the viability of Escherichia coli cells. Interruption of this gene results in cell death due to a defect in protein synthesis. We report here that the EFP protein, encoded by the efp gene, is required for in vitro reconstitution of polypeptide synthesis in a system programmed by a native template which contains each of the purified initiation factors, IF1, IF2, IF3; the elongation factors, EFTu, EFTs and EFG, and a protein called W that is required to eject tRNAs from ribosomes. The EFP protein is required for enhancing the rate and the extent of synthesis in the presence of all of the above factors. The EFP protein stimulates synthesis of poly(Phe) programmed with poly(rU) only if N-acetyl Phe-tRNA initiates the reactions under conditions that foster the dissociation of the 70S ribosome. Study of the ability of the ribosome to synthesize a number of fMet-initiated dipeptides from CCA amino acyl acceptors suggests that EFP acts to promote synthesis with acceptors that are poor donors for the the reconstituted peptidyl transferase.

Bacterial Proteins↗
PubMed2000

A case of acute myocardial infarction: intracoronary thrombus formation at a previously provoked vasospasm site.

A 58-year-old Japanese man with variant angina developed acute myocardial infarction (AMI). Emergency coronary angiography demonstrated thrombotic occlusion in the proximal site of the left anterior descending artery. The occluded region appeared to be coincident with the area in which severe vasospasm had been provoked by intracoronary administration of acetylcholine 1.5 years before the onset of AMI. This case may give us a unique opportunity to consider the role of vasospasm in the etiology of AMI.

Coronary Angiography↗
PubMed2000

Elongation factor-1alpha as a homologous complement activator of Jurkat cells.

Although increasing evidence exist suggesting that apoptotic cells activate homologous complement, the homologous complement activators are only poorly characterized. We found that cell lysate of Jurkat cells contained a homologous complement activator of 50 kDa. Digestion of the 50 kDa activator with lysylendopeptidase yielded peptide fragments, with sequences identical to those of EF-1alpha. The 50 kDa activator was removed by immunoadsorption with anti-EF-1alpha, suggesting that the 50 kDa activator is EF-1alpha. The homologous complement activation did not proceed with EGTA-serum. In addition, C4b, a fragment produced by activation of the classical or lectin pathways was found to bind with EF-1alpha. These results suggest that EF-1alpha activates the homologous complement through the classical or lectin pathway.

Amino Acid Sequence↗
PubMed2000

[Effectiveness of docetaxel plus cisplatin in large cell lung cancer showing little response to prior chemotherapy with MVP].

The present patient was a 53-year-old male who had large cell lung cancer of c-T4N1M0. We administered multi-drug regimen including mitomycin C, vindesine and cisplatin (CDDP) because of cancer invasion into the great vessels seen on a chest CT. After 3 courses, the cancer showed no change in size. Therefore, we adopted chemotherapy of docetaxel (Taxotere: TXT) and CDDP. After 4 courses, the size of the mass had decreased (partial response). The only major toxic defect was grade 3 neutropenia. A good response to TXT and CDDP could lead to complete resection of lung cancer. It is suggested that TXT is effective in the treatment of large cell lung cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Evaluation of endoscopic mucosal resection for superficial esophageal carcinoma.

Esophageal superficial carcinoma safely can be resected surgically or endoscopically. We evaluated indications for endoscopic mucosal resection (EMR) and optimal treatment modality for superficial carcinoma of the esophagus based on clinical and pathologic analyses. Between January 1, 1984, and September 30, 1999, 113 patients with superficial cancer of the esophagus underwent surgical or endoscopic resection (n = 33 patients, 36 lesions). The two-channel method, esophageal EMR-tube method or EMR cap-fitted panendoscope was used. Mucosal and submucosal cancers were classified to be epithelial layer (m1), proper mucosal layer (m2), muscularis mucosae (m3), upper third of the submucosal level (sm1), middle third of the submucosal layer (sm2), or the lower third of the submucosal level (sm3) cancers, according to criteria of the Japanese Society for Esophageal Disease. Absolute indication for EMR was restricted to m1 or m2 cancers, and relative indications for EMR included m3 or sm1 lesions. In our department, indications for EMR were not related to size or circumference of lesions. Lymph vessel invasion and lymph node metastasis markedly increased in lesions that infiltrated the lamina muscularis mucosa (m3). All lesions resected with use of EMR were 0-II (flat), and the depth of invasion in 10 0-IIa or 0-IIb lesions was m1 or m2. Twenty-one 0-IIc lesions were distributed widely from m1 to sm1. All 0-IIa+IIc lesions were m3 or sm1. Preoperative diagnosis accurately was established preoperatively in 61% of patients. Complications related to EMR were detected in 21% of patients and included perforation, stenosis, and hemorrhage. Ten patients also received radiotherapy, chemotherapy, or esophagectomy with lymph node dissection after use of EMR. No such combination therapy was administered in six patients with m3 lesions, but without lymph vessel invasion. All patients treated with use of EMR, including patients with m3 cancer who did not receive additional treatment, are living without recurrence. Local resection with use of EMR could be regarded to be the preferred treatment of superficial esophageal cancers limited to the lamina propria mucosae. Endoscopic mucosal resection also could be regarded to be the preferred treatment of m3 cancer without lymph vessel invasion. Use of additional therapy, such as radiotherapy, allows the use of EMR for m3 cancer with lymph vessel invasion or sm1 cancers.

Aged↗
PubMed2000

Crystal chemistry of hydroxyapatite deposited on titanium by sputtering technique.

Crystalline hydroxyapatite (HA) powder was coated on titanium substrate by radio frequency (RF) magnetron sputtering. The coating was homogeneous thin film and the thickness was 1microm. Crystallinity of the HA coating was low and Ca/P ratio was high as 3.0. Particle sizes were 40 to approximately 100 nm, and the crystallite size was calculated by 30 to approximately 50 nm using an X-ray diffractometry (XRD) and a transmission electron microscopy (TEM). When the coating was heated at 800 degrees C for 1 h, the low crystalline HA grew up crystalline HA, and a diffraction pattern of CaO appeared. When the coating was immersed in pH 7.4 of bovine serum for 1 week, c-axis of HA increased.

Animals↗