Biomedical subjects

Y Okamoto

Publications and source records attributed to Y Okamoto.

At least 235 records · Page 13Linked to original sources

PubMed1998

Dominant negative ATF1 blocks cyclic AMP-induced neurite outgrowth in PC12D cells.

Extension of the neuronal process is a crucial step for establishment of the neuronal network. As CREB preferentially forms heterodimers with ATF1 in PC12D cells, we examined the roles of the CREB/ATF1 heterodimer on cyclic AMP (cAMP)-induced neurite extension, using originally constructed ATF1RL, which has a point mutation at the DNA binding domain of ATF1. Transient expression of ATF1RL suppressed the protein kinase A/CREB-induced expression of the CRE reporter gene as expected. Treatment with forskolin elicited a relatively poor mRNA induction for immediate early genes in PC12D-ATF1 RL cells, a PC12D cell line stably expressing ATF1RL, in comparison with the parental PC12D cells. Furthermore, the PC12D-ATF1RL cells were proved to be defective at cAMP-induced neurite outgrowth. In contrast, both the gene expression and the differentiation after nerve growth factor treatment noted in PC12D-ATF1RL cells were at the same levels as those in the parental cells. These data provide us the first evidence that links CREB/ATF1 to the cAMP-induced differentiation of PC12 cells.

Activating Transcription Factor 1↗

PubMed1998

Intra-apheresis recruitment of blood progenitor cells in children.

BACKGROUND: Determination of the optimal duration of apheresis requires a careful examination of blood progenitor cell (BPC) kinetics during apheresis. Intra-apheresis recruitment of BPCs should be evaluated. STUDY DESIGN AND METHODS: Twenty-six apheresis procedures were performed in 13 children with various malignant disorders (ages, 10 months to 17 years; median, 7 years) to collect BPCs for autologous transplant, using a blood cell separator with 2 to 5.2 blood volumes processed. The subjects were divided into three groups according to age: below 1 year (n = 4), 2 to 10 years (n = 5), and 11 to 20 years (n = 4). BPCs were mobilized by a combination of chemotherapy and granulocyte-colony-stimulating factor (G-CSF; 2-7.5 micrograms/kg/day intravenous drip). The levels of circulating CD34+ cells and colony-forming units-granulocyte-macrophage (CFU-GM) were monitored to examine intra-apheresis recruitment. For every 50 mL per kg or 2 L of processed blood, 5-mL blood samples were collected via a central line. RESULTS: In the first apheresis procedure, more CD34+ cells were mobilized by the procedure itself in the infant group than in the older groups, and the number of cells decreased with the subject's age. When the same analysis was made during the second apheresis procedure, performed 1 day later, the levels of both CD34+ cells and CFU-GM had decreased to below the preapheresis values in all of the populations. Cell yields in the second apheresis procedure were significantly lower than those in the first. CONCLUSION: Although several factors prevent a reliable analysis, the data suggest that the intra-apheresis recruitment of BPCs may be age-specific; the continuous and prolonged supply of cells from the bone marrow to peripheral blood that occurs during apheresis is more predominant in infants, which leads to the collection of proportionately more BPCs in younger children than in their older counterparts.

Adolescent↗

PubMed1998

Analysis of long-term results of our combination therapy for squamous cell cancer of the maxillary sinus.

Seventy-four patients between 1971 and 1982 in Period I and 32 patients between 1982 and 1987 in Period II with maxillary sinus squamous cell cancer were treated by combination therapy consisting of preoperative LINAC X-ray irradiation with 5-flourouracil intra-arterial chemotherapy followed by maxillectomy and primary reconstruction. In Period II, 21 patients received preoperative cisplatinum (CPPP) microcapsule chemoembolization and pepleomycin (PEP) i.m. and or postoperative CDDP i.v. with PEP i.m. in addition to the combination therapy administered in Period I depending on systemic conditions, tumor stage and histopathological type. Five and 10-year crude survival rates were 68.9% and 55.4%, respectively, for Period I and 71.9% and 56.3% for Period II, with no significant difference between the two trials. In 21 selected patients in Period II, who had additional chemotherapy with preoperative CDDP chemoembolization and/or postoperative i.v. infusion of CDDP with pepleomycin i.m., 5 and 10-year survival rates were 85.7% and 61.9%, respectively.

Antineoplastic Agents↗

PubMed1998

Analysis of factors affecting long-term treatment results of adenoid cystic carcinoma of the nose and paranasal sinuses.

At Akita University Hospital (from 1971 to 1987) and at Chiba University Hospital (from 1983 to 1988), 17 patients with adenoid cystic carcinoma of the nose and paranasal sinuses were treated by en bloc tumor resection followed by primary reconstruction of the maxilla. Pre- and postoperative radiation was combined in 5 and 6 patients, respectively. Ten-year cancer-free survival rates were 59.3% in the 12 patients with maxillary sinus tumors and 50% in the 4 patients with nasal tumors. One patient with a sphenoid sinus tumor died within 5 years. Ten-year cancer-free survival was affected markedly by grade of tumor extension. Among T1N0M0 and T2N0M0 patients (of which there were 1 and 7, respectively), only 1 died of unrelated causes, and 6 patients survived cancer-free for more than 10 years. However, 4 of the 6 T3N0M0 patients died, and the cause of death was distant metastasis in 2, intracranial tumor extension in 1, and unrelated causes in 1. All 3 T4N0M0 patients died, 2 due to intracranial tumor extension and 1 of unrelated causes. The cause of death was distant metastasis in 3, local recurrence in 3, 2 of whom had intracranial tumor extension, and unrelated causes in 2. Prevention of distant metastasis and intracranial tumor extension was considered to be crucial for improving treatment results after en bloc tumor resection. Preoperative radiation was thought to decrease incidence of distant metastasis. In 5 patients who had preoperative radiation. 4 survived cancer-free for more than 10 years, and only 1 patient died of unrelated cause. However. of the 6 patients who had postoperative radiation, 2 died of distant metastasis and another 2 died of intracranial tumor extension. Of the 6 patients who did not have radiation therapy, the causes of death were local recurrence in 1, distant metastasis in 1 and unrelated causes in 1. Preoperative radiation in 5 patients showed histopathologically moderate or marked degeneration and necrosis of tumors in all patients. Although the number of patients in this study is too small to allow statistical analysis of the data, our present modality of treatment for adenoid cystic carcinoma of the nose and paranasal sinuses is routine combination of preoperative full dose radiation, en bloc tumor resection and primary reconstruction, including en bloc resection of the cranial base in selected T4 patients.

Antineoplastic Agents↗

PubMed1998

Continuous monitoring of hematocrit values during apheresis for allogeneic peripheral blood stem cell collection.

Rapid changes in the circulating blood volume or hemoglobin level during apheresis may pose a risk for healthy individuals donating allogeneic PBSC. In this study, a real-time noninvasive monitor CRIT-LINE was used for continuous monitoring of hematocrit values in a total of 16 aphereses performed in 4 adult (median age 30 years) and 4 pediatric donors (4 years). Donors received recombinant G-CSF (10 microg/kg s.c. for 5 days) for mobilization of PBSC. A CS3000 plus blood cell separator (Baxter) was used in two different procedures. Adults donors were subjected to modified program 1-120 using a combination of the granulocyte chamber and the small volume collection chamber (SVCC), and pediatric donors were subjected to specialized program 4 with a combination of the newly developed small volume separation chamber holder (SVSCH) and SVCC. In all of the procedures for children, the extracorporeal line was primed with 400 ml leukocyte-depleted allogeneic RBC or 200 ml autologous RBC after regular priming with normal saline, whereas none of the adult donors received this treatment. We found a marked contrast in the hematocrit kinetics during apheresis in the two cohorts/procedures. In adults, the initiation of apheresis was followed by an immediate decline in the hematocrit value over the initial 10 min until a stable plateau level was reached (7% decrease). In children, the values decreased slowly but progressively throughout the entire procedure to finally reach a 9% decrease at the completion of apheresis. These data may suggest that the use of SVSCH plus SVCC or priming with RBC can eliminate the abrupt decline in blood hemoglobin levels that occurs during apheresis.

Adult↗

PubMed1998

Subcellular localization of myosin I in A10 smooth muscle cell.

We isolated and identified a 110-kDa myosin I from porcine aorta media smooth muscle [Y. Hasegawa et al. (1996) J. Biochem. 120, 971-976]. Partial peptide sequences of the 110-kDa myosin I fragments were homologous to amino acid sequences deduced from myosin Ibeta of bovine brain and adrenal gland. We investigated biochemically the distribution of the 110-kDa myosin I by cell fractionation methods. About 10% of myosin I present in whole cells could be extracted by treatment with 0.02% saponin, which does not liberate organelles, indicating that at least 10% of myosin I present in A10 cells is associated with neither organelles nor cytoskeleton. After treatment of A10 cells with 0.5% Triton X-100, the insoluble cytoskeleton contained 45% of myosin I present in whole cells. Treatment with MgATP extracted most of myosin I from the cytoskeleton, indicating that the distribution of myosin I is maintained by binding of the myosin I head to an actin filament. On the other hand, when the cell homogenate was fractionated on sucrose density step gradients, about 80% of myosin I was associated with membranes of various densities. An attempt to dissociate the myosin I from the membranes in the presence of MgATP was not successful. These results show that about 80% of total myosin I is associated directly with membranes, not through F-actin. The amounts of myosin I associated with membranes or cytoskeleton provide evidence that myosin I in A10 cells is associated in part with only membrane and in part with both cytoskeleton and membranes. Our results lead to conclusion that myosin I exist in several states: membrane-and-cytoskeleton-associated, membrane-associated, and membrane-and-cytoskeleton-free. These states may be in dynamic equilibrium, allowing myosin I to respond to the cellular requirements.

Amino Acid Sequence↗

PubMed1998

The transepidermal absorption of prostaglandin E1 as a topical ointment: an experimental study of application over a rat skin flap.

Prostaglandin E1 (PGE1) ointment has been shown to improve the survival of skin grafts. However, the mechanism of the effects of PGE1 through topical application is unknown. A rat skin flap model was used to determine whether PGE1 is absorbed through the intact skin. The prostaglandin concentrations in the flaps in the study group were greater than those in the controls. It is suggested that PGE1 is absorbed through the skin.

Administration, Cutaneous↗

PubMed1998

Cysteine residues in the carboxyl terminal domain of the endothelin-B receptor are required for coupling with G-proteins.

We demonstrate that the human endothelin-B (ETB) receptor incorporates [3H]palmitic acid. Mutation of three putative palmitoylated cysteine residues (amino acids 402, 403 and 405) in the carboxyl terminus into serine residues (C2/3/5S) completely prevented palmitoylation of ETB. When expressed in CHO cells, C2/3/5S was localized on the cell surface, retained high affinity for ET-1 and ET-3, and was rapidly internalized when bound to the ligand. However, unlike the wild-type ETB, C2/3/5S transmitted neither an inhibitory effect on adenylate cyclase nor a stimulatory effect on phospholipase C, indicating a critical role of palmitoylation in the coupling with G-proteins, regardless of the G-protein subtype. Truncation of the carboxyl terminus, including all or a part of the three cysteine residues, gave palmitoylation-negative and -positive deletion mutants, delta 402 and delta 403. Despite the absence of the cytoplasmic tail, both delta 402 and delta 403 showed essentially the same features as C2/3/5S, except that delta 403 did transmit a stimulatory effect on phospholipase C via a pertussis toxin-insensitive G-protein, most likely a member(s) of the Gq family. These results indicated a differential requirement for the carboxyl terminus downstream from the palmitoylation site in the coupling with G-protein subtypes, i.e., it is required for the coupling with Gi but not for that with Gq.

Animals↗

PubMed1998

Definition of the region on NS3 which contains multiple epitopes recognized by dengue virus serotype-cross-reactive and flavivirus-cross-reactive, HLA-DPw2-restricted CD4+ T cell clones.

The epitopes recognized by six CD4+ CD8- cytotoxic T lymphocyte (CTL) clones established from a dengue-3 virus-immune donor were defined. (i) Three CTL clones, JK10, JK34 and JK39, were cross-reactive for dengue virus types 1-4. (ii) One clone, JK28, was cross-reactive for dengue virus types 1-4 and West Nile virus. (iii) Two clones, JK26 and JK49, were cross-reactive for dengue virus types 1-4, West Nile virus and yellow fever virus. The clones, except for JK49, recognized the same epitope on NS3 in an HLA-DPw2-restricted fashion. The smallest synthetic peptide recognized by the five CTL clones was a 10 aa peptide which comprises aa 255-264 on dengue virus NS3. JK49 recognized the overlapping epitope which comprises aa 257-266 in an HLA-DPw2-restricted fashion. Analysis of T cell receptor (TCR) usage by these T cell clones revealed that (i) JK10 and JK34 use V alpha11, and JK34 and JK28 use V beta23, and (ii) the amino acid sequences of the V(D)J junctional region of the TCR were different among these five CTL clones. There were, however, single amino acid conservations among TCRs of some of these T cell clones. These results indicate that the region on NS3 which comprises aa 255-266 contains multiple epitopes recognized by dengue serotype-cross-reactive and flavivirus-cross-reactive CD4+ CTL in an HLA-DPw2-restricted fashion and that a single epitope can be recognized by T cells which have heterogeneous virus specificities.

Amino Acid Sequence↗

PubMed1998

Effect of transient cyclic AMP elevation on DNA synthesis in rat hepatocytes at G1 phase.

Maintaining high levels of intracellular cyclic AMP (cAMP) is known to inhibit the growth of various proliferating cells including hepatocytes. We show here that transient (30 min) elevations of cAMP induced by addition of 8-bromo-cAMP (1 mmol/L) to rat hepatocytes in primary culture at three time points (12 h, 16 h and 20 h) after seeding stimulated DNA synthesis. Sustained levels of cAMP stimulated DNA synthesis to a lesser degree at a lower concentration (1 mumol/L), but inhibited it at concentrations higher than 100 mumol/L. We also determined cyclin-dependent kinase 2 (cdk2) activity in the hepatocytes during this incubation period. The transient addition of 8-bromo-cAMP at the late G1 phase increased cdk2 activity. This suggests that transient cAMP elevation in hepatocytes at the late G1 phase has a growth stimulation effect. Up-regulation of cdk2 activity may have a role in this process.

Animals↗

PubMed1998

Body surface Laplacian mapping in patients with left or right ventricular bundle branch block.

Body surface Laplacian maps (BSLMs) have been previously reported to provide enhanced capability in localizing and resolving multiple spatially separate myocardial events. However, only a few studies have been reported on the clinical applications of BSLM. To test the clinical utility of BSLMs, BSLMs and body surface potential maps (BSPMs) during ventricular depolarization for complete right or left ventricular bundle branch block (CRBBB or CLBBB) were studied in ten patients in each group. As a control group, ten healthy subjects were also studied using the same procedure. One hundred and twenty-eight electrodes were placed uniformly over the entire chest and back of the subjects. BSLMs were computed from recorded potentials, using a numerical algorithm. The BSLMs showed multiple and more localized positive and negative activities compared with the BSPMs. In healthy subjects, the BSLMs showed multiple areas of positive activity overlying the RV, LV, and the RV outflow, and negative activity corresponding to RV free-wall breakthrough and LV anterolateral breakthrough sites, whereas the BSPMs could not separate RV and LV activities. In the patients with CRBBB, the BSLMs showed more localized areas of activity corresponding to the LV apex breakthrough and LV lateral breakthrough, and separated LV lateral and posterior activation. In the patients with CLBBB, the BSLMs showed multiple RV activation, and propagating activation of LV from lateral to posterior. The BSLMs appear to provide enhanced capability in detecting multiple ventricular electrical events associated with normal and abnormal conduction and a more detailed activation sequence of both ventricles in healthy subjects and in the patients with CRBBB and CLBBB. BSLM may provide an important alternative to other imaging modalities in localizing cardiac electrical activity noninvasively.

Action Potentials↗

PubMed1998

Retrograde multiple and multifiber accessory pathway conduction in the Wolff-Parkinson-White syndrome: potential precipitating factor of atrial fibrillation.

INTRODUCTION: The determinants of susceptibility to atrial fibrillation (AF) and the existence of accessory pathway conduction have remained unidentified in the Wolff-Parkinson-White (WPW) syndrome. We tested the hypothesis that excitation inputs into the atrium over a retrograde multiple or multifiber accessory pathway during AV reentrant tachycardia (AVRT) could precipitate initiation of AF. METHODS AND RESULTS: Two hundred fifty consecutive patients with WPW syndrome underwent electrophysiologic study and radiofrequency catheter ablation. The patients were classified into two groups according to the study results: 29 with retrograde multiple or multifiber accessory pathway (MP) and 221 with retrograde single accessory pathway (SP). Compared with the SP patients, the MP patients showed a significantly higher incidence of clinical AF (MP vs SP: 19/29 vs 51/221, P < 0.01), induced AF (12/29 vs 32/221, P < 0.01), and initiated AF during ventricular pacing and AVRT (10/12 vs 17/32, P < 0.05). There were no differences between the two groups in incidence of clinical and induced AVRT (24/29 vs 200/221 and 25/29 vs 206/221, respectively), mean cycle length of induced AVRT, or electrophysiologic parameters of the accessory pathway. AF inducibility during AVRT or ventricular pacing was eliminated by partial ablation in 7 of 10 patients with MP. After total ablation, the incidence of induced AF was similar between the two groups (MP vs SP: 1/29 vs 11/221). CONCLUSION: The existence of a retrograde multiple or multifiber accessory pathway in patients with WPW syndrome is associated with a higher incidence of clinical and induced AF. Successful ablation of the retrograde multiple or multifiber accessory pathway can eliminate the induction of both AVRT and AF.

Adult↗

PubMed1998

The novel insulinotropic mechanism of pimobendan: direct enhancement of the exocytotic process of insulin secretory granules by increased Ca2+ sensitivity in beta-cells.

Pimobendan is a new class of inotropic drug that augments Ca2+ sensitivity and inhibits phosphodiesterase (PDE) activity in cardiomyocytes. To examine the insulinotropic effect of pimobendan in pancreatic beta-cells, which have an intracellular signaling mechanism similar to that of cardiomyocytes, we measured insulin release from rat isolated islets of Langerhans. Pimobendan augmented glucose-induced insulin release in a dose-dependent manner, but did not increase cAMP content in pancreatic islets, indicating that the PDE inhibitory effects may not be important in beta-cells. This agent increased the intracellular Ca2+ concentration ([Ca2+]i) in the presence of 30 mM K+, 16.7 mM glucose, and 200 microM diazoxide, but failed to enhance the 30 mM K+-evoked [Ca2+]i rise in the presence of 3.3 mM glucose. Insulin release evoked by 30 mM K+ in 3.3 mM glucose was augmented. Then, the direct effects of pimobendan on the Ca2+-sensitive exocytotic apparatus were examined using electrically permeabilized islets in which [Ca2+]i can be manipulated. Pimobendan (50 microM) significantly augmented insulin release at 0.32 microM Ca2+, and a lower threshold for Ca2+-induced insulin release was apparent in pimobendan-treated islets. Moreover, 1 microM KN93 (Ca2+/calmodulin-dependent protein kinase II inhibitor) significantly suppressed this augmentation. Pimobendan, therefore, enhances insulin release by directly sensitizing the intracellular Ca2+-sensitive exocytotic mechanism distal to the [Ca2+]i rise. In addition, Ca2+/calmodulin-dependent protein kinase II activation may at least in part be involved in this Ca2+ sensitization for exocytosis of insulin secretory granules.

Androstadienes↗

PubMed1998

Studies on inhibitory activities of fukiic acid esters on germination, alpha-amylase and carboxypeptidase A.

Fukinolic acid (1) and cimicifugic acid A (2), caffeic acid analogs, as well as rosmarinic acid (3) and caffeic acid (4) showed inhibition on seed germination and seedling growth. The potency of 1 and 2 was comparable with that of 3. Compounds 1 and 2 also showed strong inhibitory activities as well as 3 and 4 on alpha-amylase. The activity of 1 was higher than that of acarbose used as a positive control, and its 50% inhibitory concentration (IC50) was 2.41 x 10(-5) M. Compounds 1 and 2 also showed inhibitory activities strong as 3 and stronger than 4 on carboxypeptidase A. The activities of 1 and 2 were higher than that of 1, 10-phenanthroline used as a positive control.

Caffeic Acids↗

PubMed1998

Spiro-substituted piperidines as neurokinin receptor antagonists. III. Synthesis of (+/-)-N-[2-(3,4-dichlorophenyl)-4-(spiro-substituted piperidin-1'-yl)butyl]-N-methylbenzamides and evaluation of NK1-NK2 dual antagonistic activities.

To discover a novel NK1-NK2 dual antagonist, we have synthesized a series of spiro-substituted piperidines utilizing YM-35375 as a lead compound, and evaluated affinities for NK1 and NK2 receptors. In the N-methylbenzamide moiety, introduction of methoxy groups increased affinity for the NK1 receptor without a significant loss of affinity for the NK2 receptor. We also found that a conformation in which the phenyl groups of the N-methylbenzamide and 3,4-dichlorophenyl moieties are close to each other through a cis-amide bond, may be favorable for showing high affinity for the NK1 receptor and that a hydrogen bond-accepting group in the spiro-substituted piperidine moiety may be crucial for exhibiting high affinity for the NK2 receptor. Among the compounds prepared, YM-44778 (31) showed high and well-balanced affinity for NK1 and NK2 receptors (IC50 values of 18 and 16 nM, respectively). This compound also exhibited potent antagonistic activities against both NK1 and NK2 receptors (IC50 values of 82 and 62 nM, respectively) in isolated tissues.

Animals↗

PubMed1998

Insecticidal and antifungal activities of aminorhodanine derivatives.

Aminorhodanine (1) showed strong insecticidal activity against Culex pipiens pallens and Musca domestica, with respective LD50 values of 0.21 microgram/insect and 0.87 microgram/insect. Compound 1 had antifungal activity against Aspergillus niger ATCC-16404, Trichophyton mentagrophytes IFO-32412, Candida albicans ATCC-10231, Hansenula anomala OPS-308 and Penicillium expansum IFO-8800. In particular, 1 had potent antifungal activity against Aspergillus niger ATCC-16404, its minimal inhibitory concentration (MIC) being 6.25 micrograms/ml. Both activities of 1 were much higher than those of rhodanine (4), suggesting that the introduction of an amino group into N-3 of 4 plays an important role in the biological activity of rhodanine-related compounds. On the other hand, N-acetylaminorhodanine (2) and N-benzoylaminorhodanine (3) did not show either activity, suggesting that the free amino group at N-3 of 1 is closely related to the inhibitory activity of rhodanine derivatives.

Animals↗

PubMed1998

Scanning electron microscopic and cytochemical analyses of alveolar and peritoneal macrophages of mice, dogs and cats.

Alveolar and peritoneal macrophages (MPs) of mouse, dog and cat were compared in relation to their scanning electron microscopic features and the lysosomal activities of nonspecific esterase, acid phosphatase, and beta-glucuronidase. The long spindle shape of peritoneal MPs differed from the spherical form of alveolar MPs in all species. There was no difference in the morphological findings among the three animals. Murine alveolar and peritoneal MPs were strongly positive for all three enzymes. Canine and feline alveolar and peritoneal MPs were strongly positive for acid phosphatase and beta-glucuronidase, but weakly positive for nonspecific esterase. These results strongly suggest that acid phosphatase and beta-glucuronidase can be used as markers of the MPs in healthy dogs and cats.

Acid Phosphatase↗

PubMed1998

Central diabetes insipidus associated with a missense mutation in the arginine vasopressin gene that replaces Ala at the carboxyterminus of the signal peptide with Thr.

We report an 18-year-old male with a history of polyuria, polydipsia, and thirst since childhood. In a hypertonic saline infusion test, the patient's plasma vasopressin rose only to 0.28 pg/ml. In a water deprivation test, his urinary osmolality rose only to 189 mosmol/kg and then rose to 538 mosmol/kg by vasopressin administration. A T1-weighted magnetic resonance imaging (MRI) scan revealed a loss of the posterior pituitary bright spot. Sequencing of the vasopressin gene showed a heterozygous point mutation that replaced Ala at the carboxyterminus of the signal peptide with Thr. His father also had similar history, and we therefore diagnosed his illness as familial central diabetes insipidus.

Adolescent↗