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M Tokunaga

Publications and source records attributed to M Tokunaga.

At least 91 records · Page 5Linked to original sources
PubMed1998

Epstein-Barr virus involvement in gastric cancer: biomarker for lymph node metastasis.

EBV involvement in gastric cancer is characterized by episomal monoclonality, high antibody titers, EBV encoded small RNA and EBV nuclear antigen 1 expression in all tumor cells, and in the intramucosal stage, by a unique morphology. EBV involvement varies by population (approximately 7% of gastric cancers in Japan and >15% in Western countries), sex, histological type, and tumor location. The present study compares frequency of lymph node metastasis (LNM) between 170 EBV-positive and 1590 EBV-negative gastric cancer cases in Japan by level of invasiveness. Frequency of LNM increased with increasing depth of invasiveness but was consistently and significantly greater for EBV-negative cases (P = 0.0018). In particular, there were no instances of LNM among 75 EBV-positive cases as compared with 53 among 562 EBV-negative cases restricted to the mucosa and submucosa (odds ratio, 0; 95% confidence limits, 0-0.20). The finding suggests that genetic control of metastasis may differ between EBV-related and other gastric cancers. Also, the possibility that EBV-positive, noninvasive gastric cancers may not require lymph node dissection suggests that routine assay of biopsy specimens for EBV involvement could be important in populations, like that of Japan, where early gastric cancers are seen frequently.

Herpesviridae Infections↗
PubMed1998

[Analysis of 18 breast cancer patients with hypercalcemia].

A total of 91 breast cancer patients died of advanced and recurrent breast cancer at the Osaka Teishin Hospital from 1986 to 1996. There were 18 cases (19.8%) among them showing hypercalcemia (serum corrected Ca > or = 11.0 mg/dl). These 18 cases were analyzed to determine the incidence of hypercalcemia and to find a more effective treatment. All these patients had multiple bone metastases during their clinical course, and six patients (33.3%) had pathologic bone fracture just before the occurrence of hypercalcemia. Their common symptoms were general fatigue, gastrointestinal symptoms, renal dysfunction or neurological symptoms. There was no definitive correlation between clinical signs and serum calcium values. Among various therapies, the use of pamidronate disodium (Aredia) in combination with hydration, steroid and calcitonin was found to be the most effective treatment for hypercalcemia. The survival time from the diagnosis of hypercalcemia in the patients undergoing treatment with Aredia was significantly better than without it (p < 0.01). This suggests that Aredia should be effective and useful for advanced breast cancer patients with hypercalcemia.

Adult↗
PubMed1997

Epstein-Barr-virus-associated gastric cancer in Russia.

The present investigation was carried out to estimate the prevalence of EBV-associated cases among gastric carcinoma (GC) patients of Russia and the Republics of the former Soviet Union (FSU). With this aim, formalin-fixed paraffin-embedded blocks from 206 gastric carcinomas obtained from patients of the Cancer Research Center, Moscow, were investigated by EBV-encoded RNA-1 (EBER-1) in situ hybridization applied to paraffin sections. As a result, 18 GC cases (8.7%) revealed uniform EBER-1 expression restricted to the carcinoma cells. Hybridized signals not detected in non-neoplastic gastric epithelium. EBV involvement was significantly more frequent among males, especially in tumors of less differentiated types (moderately differentiated tubular adenocarcinomas and poorly differentiated solid adenocarcinomas) and located in the upper stomach (cardia and middle). Most EBV-positive GCs were characterized by strong lymphoid-compartment involvement. Our findings concerning the distribution of EBV-positive GCs by sex, site and hystological type are similar to those in Japan, however, EBV-positive rate of GC cases in Russia is higher than in Japan and lower than in USA.

Adenocarcinoma↗
PubMed1997

PTH-related peptide-like immunoreactivity in the median emminence, paraventricular and supraoptic nuclei in colchicine-treated rats.

The existence of PTH-related peptide (PTHrP) in the hypothalamus was examined by immunohistochemistry in colchicine-treated rats. Two days after intracerebroventricular administration of colchicine dense PTHrP-like immunoreactivity (LI) was observed in the external zone of the median emminence (ME). PTHrP-LI cells were found in the paraventricular nucleus, the supraoptic nucleus and the periventricular region of the third ventricule. The effects of PTHrP on intracellular Ca2+ concentrations ([Ca2+]i) were examined by a Ca2+ imaging method using fura-2 in perifused preparations of isolated rat anterior pituitary cells. The rise in [Ca2+]i induced by PTHrP was found in approximately 17% of the cells examined. These results suggest that PTHrP-LI cells in the hypothalamus may project to the ME and contribute to the anterior pituitary function.

Animals↗
PubMed1997

Asymmetric catalysis with water: efficient kinetic resolution of terminal epoxides by means of catalytic hydrolysis.

Epoxides are versatile building blocks for organic synthesis. However, terminal epoxides are arguably the most important subclass of these compounds, and no general and practical method exists for their production in enantiomerically pure form. Terminal epoxides are available very inexpensively as racemic mixtures, and kinetic resolution is an attractive strategy for the production of optically active epoxides, given an economical and operationally simple method. Readily accessible synthetic catalysts (chiral cobalt-based salen complexes) have been used for the efficient asymmetric hydrolysis of terminal epoxides. This process uses water as the only reagent, no added solvent, and low loadings of a recyclable catalyst (<0.5 mole percent), and it affords highly valuable terminal epoxides and 1, 2-diols in high yield with high enantiomeric enrichment.

Catalysis↗
PubMed1997

Purification and characterization of a GroEL homologue from the moderately eubacterial halophile Pseudomonas sp. #43.

We have purified to apparent homogeneity and characterized a molecular chaperonin GroEL homologue (hpGroEL) from a moderately halophilic eubacterium, Pseudomonas sp. #43. Although this halophilic bacterium requires 1-2 M NaCl for growth, hpGroEL did not require a high concentration of salt for its stability, ATPase activity and refold-promoting activity for denatured protein. The ATPase activity was even more halo-sensitive than that of GroEL from Escherichia coli. The hpGroEL protein promotes Mg(2+)-ATP-dependent refolding of urea-denatured alpha-glucosidase in the presence of E. coli-GroES, indicating that chaperonins 60 and 10 isolated from halophilic and nonhalophilic eubacteria, respectively, can cooperate with each other.

Adenosine Triphosphatases↗
PubMed1997

Molecular epidemiology of Epstein-Barr virus (EBV) in EBV-related malignancies.

The prevalent strain of Epstein-Barr virus (EBV) in EBV-related malignancies and in healthy adults in Southern Japan was examined by means of polymerase chain reaction (PCR) and/or restriction fragment length polymorphism (RFLP) analysis. In EBV-related gastric cancers, 51/73 cases were subtype A, 4 were subtype B and the EBNA-2 region was not amplified in 18 cases. Sixty-three were wild-type F, and only one was variant "f". Sixty-one cases had type C and 2 type D. EBNA-2 subtype A was found in 10/12 EBV-related T/NK-cell lymphomas, and 11 samples harbored the wild-type F. Neither subtype B nor the "f" variant was detected. Type C EBV was found in 8 cases and type D in 3 specimens. Two Japanese nasopharyngeal carcinomas (NPC) harbored subtype A with wild-type F and type C. Throat washings from healthy adults harbored wild-type F virus in 60/153 cases, and 25 of these samples were EBNA-2 subtype A. Type C viruses were detected in 92% of cases and type D in 7.4%. Therefore, the prevalent strain in EBV-related malignancies in Southern Japan was the same as in the healthy population in this geographical region.

Adult↗
PubMed1997

Secretion of mouse alpha-amylase from Kluyveromyces lactis.

We constructed two mouse alpha-amylase secretion vectors for Kluyveromyces lactis using the well-characterized signal sequence of the pGKL 128 kDa killer precursor protein. Both PHO5 and PGK expression cassettes from Saccharomyces cerevisiae directed the expression of mouse alpha-amylase in YPD medium at a similar level of efficiency. K. lactis transformants secreted glycosylated and non-glycosylated alpha-amylase into the culture medium and both species were enzymatically active. The K. lactis/S. cerevisiae shuttle secretion vector pMI6 was constructed, and K. lactis MD2/1(pMI6) secreted about four-fold more alpha-amylase than S. cerevisiae YNN27 harboring the same plasmid, indicating that K. lactis is an efficient host cell for the secretion and production of recombinant proteins.

Animals↗
PubMed1997

Single molecule imaging of fluorophores and enzymatic reactions achieved by objective-type total internal reflection fluorescence microscopy.

Imaging of single fluorescent molecules has been achieved in a relatively simple manner using objective-type total internal reflection fluorescence microscopy (TIRFM). Switching from epi-fluorescence microscopy to objective-type TIRFM was achieved by translation of a single mirror in the system. Clear images of single molecules of an orange fluorescent dye, Cy3, were obtained with a fluorescence-to-background ratio of 12, using a conventional high aperture objective (PlanApo, 100 x, NA 1.4) with ordinary coverslips and immersion oil. This method allowed visualization of single molecules under scanning probe microscopes. Taking advantage of the technique of single molecule imaging, individual ATP turnovers have been visualized with a fluorescent ATP analogue, Cy3-ATP, using a simple experimental strategy. Clear on/off signals were obtained that correspond to the association and dissociation of single Cy3-ATP/ADP molecules with a single myosin head molecule. This method will allow a variety of single-molecular assays of biomolecular functions to be performed using fluorescently labeled substrates, ligands, messengers, and biologically active molecules. Thus, the present technique provides a simple yet powerful and universal tool for researchers to probe the events of single molecules.

Adenosine Triphosphatases↗
PubMed1997

Single molecular assay of individual ATP turnover by a myosin-GFP fusion protein expressed in vitro.

Fusion proteins of a truncated mutant of myosin subfragment-1 (S1dC) and green fluorescent protein (GFP) were expressed in vitro by T7 RNA polymerase and rabbit reticulocyte lysate. Single S1dC-GFP fusion proteins were clearly seen and their individual ATP turnovers were directly monitored using low background total internal reflection fluorescence microscopy (LBTIRFM), recently developed by our laboratory. LBTIRFM using GFP as a fluorescent tag allowed us to assay functions of single protein molecules expressed in vitro. Thus, the results suggested that this method may be particularly useful to analyze functions of proteins that cannot be produced in an active form and/or in large quantities in conventional heterologous expression systems.

Adenosine Triphosphate↗
PubMed1997

Salivary gland tumors among atomic bomb survivors, 1950-1987.

BACKGROUND: Malignant and benign tumors of the salivary glands have been associated with exposure to ionizing radiation from various sources, including the atomic bombings in Hiroshima and Nagasaki. However, questions remain unanswered regarding the nature and size of the risk and specific types of tumors involved. METHODS: The incidence and pathology of malignant and benign tumors of the salivary glands was studied in the Life Span Study cohort of atomic bomb survivors followed by the Radiation Effects Research Foundation (RERF) in Hiroshima and Nagasaki, Japan. Incident cases diagnosed during the period 1950-1987 were ascertained from the tumor and tissue registries of Hiroshima and Nagasaki and supplemented by additional case findings from autopsy, biopsy, and surgical specimens maintained at RERF and other institutions. Pathology slides and medical documents were reviewed by a panel of four pathologists who classified tumors using the World Health Organization classification scheme. Analyses were performed of histologic features associated with radiation exposure. RESULTS: Of 145 tumors of the salivary glands identified (119 of the major and 26 of the minor salivary glands), 120 (83%) were histologically confirmed by the current investigators. Among 41 malignant tumors, the frequency of mucoepidermoid tumor was disproportionately high at high radiation doses (P = 0.04); among 94 benign tumors, the frequency of Warthin's tumor increased with increasing radiation dose (P = 0.06). The nature of the tumor was undetermined for the remaining ten cases. Mortality from malignant tumors of the salivary gland was inversely related to radiation dose, reflecting the predominance of mucoepidermoid carcinoma at high dose levels in this series. In one case with high radiation exposure, mucoepidermoid carcinoma of the parotid gland was accompanied by a preexisting or coexisting Warthin's tumor. CONCLUSIONS: These findings, supported by population-based analyses in a companion study reported elsewhere, suggest a causal role for ionizing radiation in salivary gland tumorigenesis, particularly for mucoepidermoid carcinoma, and in the induction of one type of benign tumor (Warthin's tumor).

Adult↗
PubMed1997

Subpiconewton intermolecular force microscopy.

We refined scanning probe force microscopy to improve the sensitivity of force detection and control of probe position. Force sensitivity was increased by incorporating a cantilever with very low stiffness, 0.1 pN/ nm, which is over 1000-fold more flexible than is typically used in conventional atomic force microscopy. Thermal bending motions of the cantilever were reduced to less than 1 nm by exerting feed-back positioning with laser radiation pressure. The system was tested by measuring electrostatic repulsive forces or hydrophobic attractive forces in aqueous solutions. Subpiconewton intermolecular forces were resolved at controlled gaps in the nanometer range between the probe and a material surface. These levels of force and position sensitivity meet the requirements needed for future investigations of intermolecular forces between biological macromolecules such as proteins, lipids and DNA.

Eyeglasses↗
PubMed1997

Myosin subfragment-1 is fully equipped with factors essential for motor function.

The sliding velocity of actin filaments propelled by chicken skeletal myosin subfragment-1 (S1) was measured when the tail end of S1 was specifically bound to the glass surface. To achieve the specific binding, a regulatory light chain was replaced by a recombinant fusion protein of biotin-dependent transcarboxylase (BDTC) and chicken gizzard smooth muscle regulatory light chain (cgmRLC). The BDTC-cgmRLC of S1 was then attached to the glass surface using a biotin-avidin system. The velocity of actin filaments caused by S1 bound to the surface in this manner was 6.8 +/- 0.6 microm/sec at 29 degrees C, which was 3.5-fold greater than that (1.9 +/- 0.3 microm/sec) when bound directly to the surface as in previous studies, but similar to that caused by native chicken skeletal myosin (6.5 +/- 0.6 microm/sec). The actin-activated Mg-ATPase activity was similar to that of S1 before the RLC of S1 was exchanged for BDTC-cgmRLC. The results indicate that S1 can produce a normal fast movement of actin filaments as well as hydrolyse ATP and generate force.

Animals↗
PubMed1997

Imaging and nano-manipulation of single biomolecules.

We have developed a new technique for imaging single fluorescent dye molecules by refining epifluorescence and total internal reflection fluorescence microscopies. In contrast to previously reported single fluorescent molecule imaging methods, in which specimens were immobilized on an air-dried surface, our method enables video-rate imaging of single molecules in aqueous solution. This approach enabled us to directly image the processive movement of individual fluorescently labeled kinesin molecules along a microtubule. This method was also used to visualize individual ATP turnover reactions of single myosin molecules. The method can be combined with molecular manipulation using an optical trap. A single kinesin molecule attached to a polystyrene bead was brought into contact with a microtubule adsorbed onto the glass surface. The lifetime of bound Cy3-nucleotide in the absence or presence of the microtubule was 10 s or 0.08 s, respectively, showing that ATPase activity of the kinesin is strongly activated by microtubules. As the present system is equipped with a nanometer sensor, elemental steps of a single kinesin molecule can also be measured. By simultaneously measuring the individual ATP turnovers and elementary mechanical events of a single kinesin molecule, we will be able to obtain a clear answer to the fundamental problem of how the mechanical events are coupled to the ATPase reaction.

Adenosine Triphosphate↗
PubMed1997

Inositol 1,4,5-trisphosphate and cyclic ADP-ribose mobilize Ca2+ in a protist, Euglena gracilis.

Inositol 1,4,5-trisphosphate (InsP3) and cyclic ADP-ribose (cADPR) released Ca2+ from microsome fraction prepared from Euglena gracilis in dose-dependent manners. Caffeine, which also induced Ca2+ release from the microsomes, caused desensitization of the Ca2+ response to cADPR, although the Ca2+ response to InsP3 was not affected by caffeine. Further, ruthenium red inhibited the Ca2+ release induced by cADPR, but not by InsP3. These results suggest that cADPR functions as an endogenous messenger to activate a caffeine-sensitive, Ca(2+)-release mechanism, whereas InsP3 induces Ca2+ release by a distinct mechanism in E. gracilis.

Adenosine Diphosphate Ribose↗
PubMed1997

Oculopharyngeal muscular dystrophy in Japan.

Oculopharyngeal muscular dystrophy (OPMD) in the European population has been frequently diagnosed, but except for one black family, the occurrence in other ethnic groups is uncertain. We identified two unrelated OPMD Japanese families, including 34 affected individuals. Major clinical manifestations were bilateral ptosis and dysphagia starting after age 40. Histologic studies of limb muscles revealed mild myogenic changes, occasional rimmed vacuoles, and small angulated fibers. By contrast, cricopharyngeal muscle showed a marked loss of fibers and massive proliferation of connective tissue. Intranuclear tubulofilamentous inclusions (ITFI) of 8.5 nm outer diameter were observed in 2-5% of the nuclei in four different biopsied muscles. One patient with recurrent aspirations underwent successful cricopharyngeal myotomy. Aerodynamic examination was useful to evaluate velopharyngeal closure function. Our investigations revealed that OPMD is a geographically widespread disorder, and ITFI may be the specific morphologic hallmark.

Biopsy↗
PubMed1997

Dual-colour microscopy of single fluorophores bound to myosin interacting with fluorescently labelled actin using anti-Stokes fluorescence.

We have refined prismless total internal reflection fluorescence microscopy with extremely low background to visualize single fluorophores attached to protein molecules interacting with a filamentous biopolymer labelled with different colour fluorophores. By using Stokes and anti-Stokes fluorescence, two different colour fluorescences from two different colour fluorophores excited with a single wavelength laser can be observed simultaneously. This microscopy was applied to visualize motor proteins, actin and myosin molecules. Single myosin molecules labelled with a tetramethylrhodamine-5-iodoacetamide interacting with a BODIPY FL-labelled actin filament, a filamentous polymer of actin molecules, were observed clearly and simultaneously in aqueous solution. Individual hydrolysis reactions of Cy3-labelled ATP by single myosin molecules and sliding of a BODIPY FL-labelled actin filament along the myosin molecules could also be observed simultaneously. Thus, this technique is useful for observing single molecular processes of proteins interacting with a biological macromolecule such as an actin filament and a DNA.

Actins↗