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Biomedical subjects

Y Nakase

Publications and source records attributed to Y Nakase.

At least 19 recordsLinked to original sources
PubMed2001

The Schizosaccharomyces pombe spo20(+) gene encoding a homologue of Saccharomyces cerevisiae Sec14 plays an important role in forespore membrane formation.

The Schizosaccharomyces pombe spo20-KC104 mutation was originally isolated in a screen for sporulation-deficient mutants, and the spo20-KC104 mutant exhibits temperature-sensitive growth. Herein, we report that S. pombe, spo20(+) is essential for fission yeast cell viability and is constitutively expressed throughout the life cycle. We also demonstrate that the spo20(+) gene product is structurally homologous to Saccharomyces cerevisiae Sec14, the major phosphatidylinositol transfer protein of budding yeast. This structural homology translates to a significant degree of functional relatedness because reciprocal complementation experiments demonstrate that each protein is able to fulfill the essential function of the other. Moreover, biochemical experiments show that, like Sec14, Spo20 is a phosphatidylinositol/phosphatidylcholine-transfer protein. That Spo20 is required for Golgi secretory function in vegetative cells is indicated by our demonstration that the spo20-KC104 mutant accumulates aberrant Golgi cisternae at restrictive temperatures. However, a second phenotype observed in Spo20-deficient fission yeast is arrest of cell division before completion of cell separation. Consistent with a direct role for Spo20 in controlling cell septation in vegetatively growing cells, localization experiments reveal that Spo20 preferentially localizes to the cell poles and to sites of septation of fission yeast cells. We also report that, when fission yeasts are challenged with nitrogen starvation, Spo20 translocates to the nucleus. This nuclear localization persists during conjugation and meiosis. On completion of meiosis, Spo20 translocates to forespore membranes, and it is the assembly of forespore membranes that is abnormal in spo20-KC104 cells. In such mutants, a considerable fraction of forming prespores fail to encapsulate the haploid nucleus. Our results indicate that Spo20 regulates the formation of specialized membrane structures in addition to its recognized role in regulating Golgi secretory function.

Amino Acid Sequence↗
PubMed2001

[A case of multiple liver metastases from breast cancer successfully treated with intra-arterial administration of paclitaxel].

A 57-year-old woman underwent modified radical mastectomy for left breast cancer (T4bN1M1: stage IV) in September 1999. Four-cycle CAF therapy had been administered as adjuvant therapy, but multiple recurrent tumors in the liver had grown bigger and the tumor marker (CEA) increased in value. Because CAF therapy was not effective, we tried to treat the patient with systemic and intra-arterial chemotherapy using paclitaxel. The side effects of this treatment were mild nausea and appetite loss, which required no treatments. This treatment reduced the multiple liver metastases on an abdominal CT and was thought to produce a partial response (PR). The time to response was the 101st day and PR has been continued.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Selective thermocoagulation of unresectable pancreatic cancers by using radiofrequency capacitive heating.

Recent investigations indicated that hyperthermia has antitumor effects. Several interstitial hyperthermic techniques were developed, and their clinical usefulness and safety were evaluated. However, few authors have attempted to study the use of interstitial hyperthermia for the treatment of pancreatic carcinomas. Therefore the efficacy of local selective thermocoagulation by radiofrequency was evaluated in 20 patients with unresectable carcinomas of the pancreas. A laparotomy and radiofrequency heating were performed in 20 patients with unresectable pancreatic carcinomas after informed consent. Local heat coagulation was induced by a 13.56-MHz radiofrequency pulse, produced by the heating apparatus. Four 2-cm needle electrodes were placed in the tumor, in a square array, at intervals of 2 cm. The heat was then administered for 15 min at a controlled temperature of 50 degrees C in the radiofrequency field (2x2x2 cc). All the patients were evaluated by computed tomographic scanning. Tumor markers in the blood also were assayed before and after the heating. Follow-up computed tomographic scans demonstrated that the tumor mass was enhanced heterogeneously, and after selective thermocoagulation, images revealed a change to a homogeneous low-density area. The blood levels of tumor markers decreased to below pretreatment values in 15 patients. Of the 20 cases treated with thermocoagulation, two had critical complications. One patient had septic shock, and another had gastrointestinal bleeding. The other 18 patients had no significant complications. These observations suggest that the selective thermocoagulation of tumor tissues using this equipment was relatively safe. These results justify further clinical trials for the treatment of patients with unresectable tumors without metastasis, or patients with benign pancreatic tumors such as insulinomas.

Adenocarcinoma↗
PubMed1999

Selective ablation of porcine and rabbit liver tissue using radiofrequency: preclinical study.

Temperature changes and their distribution induced by 13.56-MHz radiofrequency (RF) heating of agar phantom and porcine and rabbit liver were investigated. It was possible to produce selective local heating of approximately 50 degrees C in the RF field of 2 x 2 x 2 cm(3) of the pig or rabbit liver. Coagulation necrosis after heating became pronounced and the margin between the coagulated lesion and normal tissue became clearer with time. Within 1 week after RF heating at 50 degrees C for 20 min, the coagulated area was replaced selectively and totally by necrotic tissue.

Animals↗
PubMed1996

[Selective thermocoagulation of unresectable malignant tumors using radiofrequency].

Based on our experimental findings on porcine liver, we have been conducting a clinical trial of selective hyperthermia by radiofrequency (RF) capacitive heating with laparotomy for patients with unresectable malignant tumors. In 10 patients with malignant tumors (8 carcinoma of the pancreas, 2 carcinoma of the gallbladder), laparotomy and RF heating were performed after informed consent. The local heat coagulation was produced by heating equipment using 13.56 MHz radiofrequency produced by Omron Corporation, Japan. Four 2-cm electrode needles were placed in the tumor in a square array at intervals of 2.0 cm. Hyperthermia was given for 30 min with a controlled temperature of 50 degrees C in the RF field (2 x 2 x 2 cm3). That of the surrounding area was maintained at less than 40 degrees C. The calculated volume treated by RF ranged between (2 x 2 x 2 cm3) x 1 and (2 x 2 x 2 cm3) x 6. We followed all patients by computed tomographic (CT) scan 2 weeks after coagulation. Tumor markers in the blood were assayed before and 14 days after heating. Follow-up CT scans demonstrated that after the tumor mass had been heterogeneously enhanced, it changed to a homogeneous low-density area in 6 of 10 patients. The levels of tumor markers decreased to lower than the pre-treatment values in 9 of 10 patients. In all patients, the changes in CT scans and/or decrease in the markers were confirmed. Complications such as bleeding or abscess formation were not observed. It was suggested that the selective hyperthermia was safely produced by this equipment. The encouraging results in these patients justify further clinical trials.

Biomarkers, Tumor↗
PubMed1995

Extensive tissue oxygenation associated with mitochondrial DNA mutations.

Extensive tissue oxygenation in the mitochondrial myopathy patients caused by the mitochondrial DNA mutations was first demonstrated noninvasively by a tissue oxymeter measuring near infrared light. The extent of oxygenation of the tissue due to dysfunction of mitochondria correlated with the seriousness of mitochondrial DNA mutations resulting in defects in oxidative phosphorylation system, and causing suppressed oxygen utilization. Such oxygen stress furthers mitochondrial DNA mutations during the progressive course of the disease. This noninvasive diagnosis will find useful application in the diagnosis and management of patients of advanced age.

Adult↗
PubMed1994

Purification and characterization of Bordetella calmodulin-like protein.

Bordetella calmodulin-like protein was purified from culture supernatant fluid of B. pertussis, B. parapertussis and B. bronchiseptica by successive chromatography on hydroxyapatite, Toyopearl HW-50F and QAE-Toyopearl 550C columns. The purified calmodulin-like protein appeared to be homogeneous by SDS-polyacrylamide gel electrophoresis. The apparent molecular mass of calmodulin-like protein on SDS-polyacrylamide gel electrophoresis was 10 kDa, which was smaller than bovine brain calmodulin (17 kDa). The purified calmodulin-like protein activated both Bordetella adenylate cyclase and mammalian phosphodiesterase in a Ca(2+)-dependent manner. This activation was inhibited by calmodulin antagonists. The calmodulin-like protein, like calmodulin, was retained by a hydrophobic resin in the presence of Ca2+ and eluted by the addition of EDTA. These results indicated that the Bordetella calmodulin-like protein is closely related to calmodulin. As a putative calmodulin the extracellular calmodulin may be involved in Bordetella pathogenesis.

Adenylyl Cyclases↗
PubMed1994

Color Doppler imaging of orbital venous flow in dysthyroid optic neuropathy.

Color Doppler imaging was performed to evaluate the venous stasis in 39 orbits, including 9 optic neuropathy orbits, of 20 patients with dysthyroid ophthalmopathy and 22 orbits of 11 healthy subjects. The superior ophthalmic vein (SOV) was detected in 26 dysthyroid ophthalmopathy orbits and in 13 control orbits. The blood flow in the SOV was in the anteroposterior direction in 20 dysthyroid ophthalmopathy orbits and in 13 control orbits. Reversed flow, ie, the flow in the posteroanterior direction, was seen in 6 dysthyroid ophthalmopathy orbits and in none of the control orbits. In dysthyroid ophthalmopathy orbits, the blood flow in the SOV was reversed in 5 (36%) of the 14 orbits with apical orbital crowding observed on computed tomography, which means there was compression of the optic nerve by enlarged extraocular muscles, as compared to in 1 (4%) of the 25 orbits without apical orbital crowding (P < 0.05). The percentage of the orbits having reversed flow in SOV was 44% of dysthyroid ophthalmopathy orbits with optic neuropathy as opposed to 7% of those without optic neuropathy (P < 0.05). Reversed blood flow in the SOV strongly supported the existence of severe venous stasis in the orbits, which may be related to the development of dysthyroid optic neuropathy.

Adolescent↗
PubMed1992

Bordetella heat-labile toxin causes release of radioactivity from smooth muscle cells labeled with [14C]arachidonic acid.

The effect of Bordetella heat-labile toxin (HLT) on cultured vascular or tracheal smooth cells labeled with [14C]arachidonic acid for 3 h was examined. At 37 degrees C, in the presence of Ca2+, HLT induced the release of radioactive substances from the cells in a dose-dependent manner but HLT had no effect on release of radioactivity from cells at 0 degrees C or in the absence of Ca2+. After cells were exposed to HLT, a 2-h lag period occurred before release of radioactivity was detected. The substances released from cells by HLT were identified as arachidonic acid and phosphatidylcholine.

Animals↗
PubMed1992

Heat-labile toxin from Bordetella parapertussis induces contraction of smooth muscle cells in culture.

The ability of Bordetella heat-labile toxin (HLT) to contract various types of cells in culture was examined. HLT from B. parapertussis induced contraction of cultured smooth muscle cells from trachea, intestine, uterus and vas deferens as well as from aorta. The time required for contraction decreased as the dose of B. parapertussis HLT increased from 3 to 100 MID/ml. Upon exposure of cells to concentrations of toxin greater than 100 MID/ml, at least 2 hr was required for contraction. HLT from B. parapertussis did not affect cultured cardiac or skeletal muscle cells within 8 hr after the exposure to HLT (100 MID/ml). No effect on other types of primary culture cells or established cells such as Chinese hamster ovary (CHO) cells has been described. These data indicate that the primary target cells for HLT might be smooth muscle cells.

Animals↗
PubMed1992

Cytotoxic effects of antitumor agents on mouse tracheal organ cultures at ultrastructural level.

A cytotoxic effect of antitumor agents (mitomycin C;MMC, adriamycin;ADM, bleomycin;BLM, 5-fluorouracil;5-FU, and cisplatin;CDDP) on ciliated epithelial cells of mouse tracheal organ cultures was studied in transmission electron microscopy. Mouse tracheal rings incubated with each agent in a concentration of 1 microgram/ml or 10 micrograms/ml were observed after 1, 2, and 20 hr of the incubation. After 2 hr, the ciliated epithelial with MMC or ADM of 1 microgram/ml exhibited appearance of lipid droplets in the nonciliated cells and the swelling of mitochondria and epithelial cells. Further incubation of 20 hr with those agents resulted in the pronounced degeneration including the ciliary subsidence into intracellular spaces, balloon-like ciliary swelling, and cellular destruction. Whereas, the ciliated epithelia with 5-Fu, BLM or CDDP did not show any notable change within 2 hr. After 20 hr, these exhibited the swelling of mitochondria, cilia and epithelial cells. The ciliated epithelia incubated with MMC or ADM of a greater concentration of 10 micrograms/ml showed remarkable cytotoxic effects after 1 hr of the incubation. The morphological changes in the epithelial cells with 1 hr incubation were almost similar to those of 20 hr incubation with the 1 microgram/ml. After 20 hr, the cellular degeneration proceeded to extremely flattened epithelial cells with disappearance of cilia and appearance of numerous vacuoles. Those with 5-FU, BLM or CDDP of 10 micrograms/ml exhibited ciliary swelling after 2 hr, but the morphological changes of 5-FU were more remarkable than those of BLM or CDDP. After 20 hr, the pronounced degeneration was observed, and it was similar to one of MMC or ADM of 2 hr incubation.

Animals↗
PubMed1991

Role of rectus muscle enlargement in clinical profile of dysthyroid ophthalmopathy.

Using logistic regression analysis, a correlation between enlargement patterns of the 4 rectus muscles and the occurrence of a variety of dysthyroid ophthalmopathy-associated ocular symptoms were analyzed in 698 eyes of 349 patients with this disorder. The condition of each rectus muscle was evaluated by computed tomography, and the various ocular symptoms were classified according to the Inoue classification system. The enlargement pattern, particularly when involving the inferior and medial recti, was found to have a strong statistical correlation with the occurrence of individual ocular symptoms. Additionally, the probabilities of the occurrence of most of the ocular symptoms were generally greater in those eyes with 2-, 3- or 4-muscle enlargement patterns than in those eyes with one or no enlarged rectus muscle.

Adult↗
PubMed1990

Development of a cell culture assay for Bordetella parapertussis heat-labile toxin.

A cell culture assay for heat-labile toxin isolated from Bordetella parapertussis has been developed. In this assay, the ability of heat-labile toxin to induce contraction of vascular smooth muscle cells is measured. The method allows for detection of as little as 0.6 ng/ml of the toxin. The results obtained from this in vitro assay correlated well with those obtained with in vivo assays indicating that the cell culture assay may be a useful alternative to animal assays.

Animals↗
PubMed1990

Inhibition of heat-labile toxin from Bordetella parapertussis by fatty acids.

The ability of heat-labile toxin (HLT) from Bordetella parapertussis to induce skin lesions in guinea pigs was found to be inhibited by lipids isolated from skin layers of adult mice, which are refractory to the lesion-inducing activity of HLT. These lipids were identified as linoleic and oleic acids. Other long-chain unsaturated fatty acids were also found to inhibit HLT; however, fatty alcohols, neutral lipids, phospholipids, cholesterol, prostaglandin, and leukotriene had no measurable effects on HLT action. The data presented in this report indicate that the ability of HLT to induce skin lesions in animals may depend, at least in part, on the free fatty acid content of the skin layer.

Animals↗