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Biomedical subjects

H Tokunaga

Publications and source records attributed to H Tokunaga.

At least 19 recordsLinked to original sources
PubMed1998

Effect of preceding in vivo sublethal ischemia on the evoked potentials during secondary in vitro hypoxia evaluated with gerbil hippocampal slices.

We investigated the mechanism of 'ischemic tolerance phenomenon' by characterizing the physiological events, modified by preceding sublethal ischemia, during secondary hypoxia. Slices from brains after pretreatment of sublethal forebrain ischemia were subjected to a 70% reduction of PO2 (threshold hypoxia). Although evoked potentials disappeared completely in five of eight slices from sham-operated brain, they were sustained in 28/32 slices from pretreated brains. This study indicates that the maintenance of membrane function might be the mechanism of ischemic tolerance.

Animals↗
PubMed1998

Endothelin-1 inhibits endothelin-converting enzyme-1 expression in cultured rat pulmonary endothelial cells.

BACKGROUND: The lung expresses large amounts of endothelin-converting enzyme-1 (ECE-1), which catalyzes a step in the biosynthesis of potent vasoactive endothelin-1 (ET-1) from the inactive intermediate big ET-1. Because there has been no report concerning a possible relationship between ET-1 and ECE-1, we investigated the effects of ET-1 on ECE-1 expression in cultured rat pulmonary endothelial cells. METHODS AND RESULTS: ECE-1 messenger RNA (mRNA) and protein expression in cultured endothelial cells were assayed by Northern and Western blotting, respectively. Incubation with ET-1 for 6 hours caused a significant decrease in ECE-1 mRNA expression. The action of ET-1 on ECE-1 mRNA expression was antagonized by pretreatment with BQ788, a specific ETB receptor antagonist, but not by pretreatment with BQ123, a specific ETA receptor antagonist. The expression of ECE-1 protein was also inhibited at 6 hours after incubation with ET-1. The effects of ET-1 on ECE-1 mRNA and protein expression were shown to be mimicked by ionomycin, a calcium ionophore, but not by 12-O-tetradecanoylphorbol 13-acetate, a protein kinase C activator. CONCLUSIONS: The present results demonstrate that ET-1 suppressed ECE-1 protein levels by inhibiting ECE-1 mRNA expression through the ETB receptor, suggesting the existence of a feedback action of ET-1 on ECE-1 in pulmonary endothelial cells.

Animals↗
PubMed1998

Expression of RANTES by normal airway epithelial cells after influenza virus A infection.

The chemokine regulated on activation, normal T cells expressed and secreted (RANTES), is a C-C chemokine and a potent chemoattractant for monocytes, T lymphocytes, basophils, and eosinophils. Its expression by human airway epithelium has been demonstrated both in vitro and in vivo. We investigated whether RANTES is expressed by normal human airway epithelial cells after influenza viral infection and examined its bioactivity. Epithelial cells were obtained from bronchial tissue or nasal polyps of patients who had undergone lobectomy for lung cancer or polypectomy for nasal polyps. These cells were cultured by the outgrowth method. Cultured cells were infected with influenza virus A (subtype H3N2) after which the supernatants and the cells were collected 8 to 72 h after infection. RANTES mRNA (messenger RNA) was analyzed by the reverse transcriptase-polymerase chain reaction and Southern blot analysis of its product. Concentrations of RANTES in the supernatants were analyzed by enzyme-linked immunosorbent assay. RANTES protein and mRNA were not detected in the media of uninfected cells. PCR products for RANTES were clearly detected in nasal and bronchial epithelial cells 24 h after infection. Southern blot analysis confirmed that the PCR products were indeed specific for RANTES mRNA. Twenty-four to 72 h after infection, significant levels of RANTES protein were detected in culture media. We also investigated the chemotactic activity of the supernatant of cultured cells. The supernatant of the cells 48 h after infection had potent chemotactic activity for eosinophils, which was attenuated by the addition of anti-RANTES antibodies. These findings suggest that influenza virus infection may induce expression of bioactive RANTES by normal human bronchial and nasal epithelial cells.

Bronchi↗
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

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

Vascular endothelial growth factor is an essential molecule for mouse kidney development: glomerulogenesis and nephrogenesis.

Homeostasis of body fluid is maintained by the kidneys, which contain two million glomeruli for blood filtration. A glomerulus is formed by growth of Bowman's capsule harmonized with a capillary during kidney development. The vascular endothelial growth factor (VEGF) is an essential angiogenic cytokine, and VEGF deficiency is known to be fatal in mice in early embryonic stages. As secretions of VEGF from cultured kidneys vary according to developmental stages, the role of VEGF in kidney development was studied in vivo by blocking the endogenous VEGF activity with antibody in newborn mice, in which most organs are already developed but kidneys are still developing. The antibody-treated animals showed normal growth but systemic edema. Vessel formation in the superficial renal cortex was disturbed, nephrogenic areas were diminished, and the number of developing nephrons decreased significantly. Many abnormal glomeruli, lacking capillary tufts, were observed in the antibody-treated mice, and VEGF expression in their Bowman's capsule showed a compensatory increase. These results suggest that VEGF mediates communication between the Bowman's capsule and capillary endothelial cells for developing a glomerulus as well as promoting nephrogenesis. In conclusion, VEGF is likely to be an essential molecule for kidney development, and especially for glomerulogenesis.

Animals↗
PubMed1997

Death attributed to the toxic interaction of triazolam, amitriptyline and other psychotropic drugs.

A 71-year-old man was found dead in a car into which exhaust fumes had been introduced. His wife who was in the same car recovered consciousness following hospitalization. She claimed that they had both attempted suicide by taking a large number of sleeping pills. Autopsy revealed no significant external injuries or medical disorders that would have led to the husband's death. The concentrations of alcohol and carbon-monoxide hemoglobin in his whole blood were 0.26 mg/ml and < 10%, respectively. Therefore, poisoning by carbon monoxide from the exhaust fumes was ruled out, and further toxicological examinations were undertaken. Triazolam, pentobarbital, amitriptyline and bromazepam were all detected in the tissues of the victim; whole blood concentrations were 45.60, 386.4, 521.2 and 166.7 ng/g, respectively. Triazolam (7.350 ng/g) and pentobarbital (288.2 ng/g) were also detected in the whole blood of the wife, collected 17 h after admission to hospital. When evaluating these results in the light of existing literature, we concluded that the victim and his wife had indeed attempted suicide by taking triazolam and pentobarbital. However, only the man had died of triazolam poisoning due to its apparently lethal combination with amitriptyline and other psychotropic drugs which had been prescribed to treat his depression.

Aged↗
PubMed1997

Sensitive determination of sulpiride in human plasma by high-performance liquid chromatography.

We developed a simple, sensitive and reliable method for the determination of sulpiride, a specific antipsychotic drug, in human plasma using high-performance liquid chromatography. A structurally related benzamide, tiapride, was used as the internal standard. A Sep-Pak C18 cartridge was used to extract a sample from 1 ml of plasma. The extract was dissolved in methylene chloride, and then back-extracted with 0.01 M hydrochloric acid. The aqueous layer was put on a octadecylsilica column with a mobile phase of 50% acetonitrile in 0.01 M phosphate buffer (pH 3.0). A fluorescence detector with excitation at 300 nm and emission at 365 nm was used for detection. The calibration curve was linear in the concentration range of 10-1500 ng/ml, and the lower limit of detection was 1 ng/ml. We used this method to examine plasma levels of sulpiride in 14 inpatients being treated with sulpiride for 6 months. The determined plasma levels were 70.1-1121.2 ng/ml, and the correlation between daily dose and plasma concentration was positive. This simple, reliable method is expected to be put to good use in forensic and hospital laboratories.

Adult↗
PubMed1997

Selective determination of sultopride in human plasma using high-performance liquid chromatography with ultraviolet detection and particle beam mass spectrometry.

We developed a sensitive and selective method for determining levels of sultopride, a neuroleptic drug of the substituted benzamide, in human plasma using high-performance liquid chromatography (HPLC) combined with UV detection and particle beam mass spectrometry (PBMS). Sultopride was extracted with tert.-butylmethyl ether using a salting-out technique. Tiapride served as an internal standard (I.S.). Sultopride and I.S. were separated by HPLC on a silica column with a mobile phase of acetonitrile-0.1 M ammonium acetate (94:6, v/v). The calibration curves were linear over the concentration range from 5 to 1000 ng/ml by HPLC with UV detection and from 10 to 1000 ng/ml with PBMS detection. The limit of quantitation was 5 ng/ml with UV detection and 10 ng/ml with PBMS detection. The absolute recovery was 92% and the within-day coefficients of variation were 2.9-7.1% at plasma concentrations from 50 to 500 ng/ml, determined by HPLC with UV detection. Using this method, we measured the plasma concentrations of sultopride with replicate analyses in four hospitalized patients and steady-state plasma levels were determined to be 161.6 +/- 30.8, 321.1 +/- 93.7, 726.5 +/- 143.1 and 1273.6 +/- 211.2 ng/ml, respectively.

Adult↗
PubMed1997

Teacher consultation: impact on teachers' effectiveness and students' cognitive competence and achievement.

Teachers from six ethnically diverse inner-city schools participated in weekly mental health consultation for more than two years. Using a quasi-experimental design, a longitudinal sample of 91 teachers and 209 students was assessed periodically through multiple standardized measures. Results indicate that a low-cost, indirect intervention had a direct impact on teachers' sense of professional competence and was linked to positive changes in students' sense of cognitive competence and their academic achievement.

Achievement↗
PubMed1997

Combined carboplatin and cisplatin therapy in patients with advanced non-small cell lung cancer.

Combining cisplatin and carboplatin may eliminate some of the toxic effects of each agent and permit the use of higher doses, because these agents have different pharmacodynamics and dose-limiting toxicities. We investigated the safety and efficacy of these agents in combination. The toxicity profile was evaluated in a Phase I trial in 18 patients with advanced non-small cell lung cancer (NSCLC). Carboplatin was administered in doses ranging from 200 to 400 mg/m2 on day 1 and cisplatin at a dose of 80 mg/m2 on day 3. Only one cycle of chemotherapy was administered. Thrombocytopenia was the dose-limiting toxic effect. The maximal tolerated dose of carboplatin was 350 mg/m2. We then investigated the efficacy of the optimal dose of this combined chemotherapy in a Phase II trial in 13 patients. We used a carboplatin dose of 300 mg/m2 for safety in the Phase II trial. Three of 13 patients developed grade 3-4 hematologic toxicity, which was improved without major complications. A partial response was observed in 5 of 13 patients (38.5%). Combination chemotherapy with carboplatin (day 1, 300 mg/m2) and cisplatin (day 3, 80 mg/m2) showed promising effects in patients with advanced NSCLC.

Aged↗
PubMed1997

Induction of apoptosis in human eosinophilic leukemic cell line (EOL-1).

Exposure of human eosinophilic leukemic EOL-1 cells to H2O2, ascorbic acid derivatives, actinomycin D, low-molecular-weight polyphenols, UV irradiation, or hyperthermia resulted in nuclear fragmentation, but failed to induce internucleosomal DNA cleavage. The findings suggest that internucleosomal DNA fragmentation is not a universal biochemical hallmark of apoptosis. Removal of Ca2+ ions from the culture medium significantly reduced the cytotoxic activity of sodium ascorbate, but not that of H2O2. H2O2 significantly elevated the intracellular Ca2+ concentration, with or without Ca2+ in the culture medium. This suggests that sodium ascorbate and H2O2 initiate cell death by different mechanisms. Induction of apoptosis in in vitro systems might be useful in studying the pathogenesis of allergy or asthma.

Apoptosis↗
PubMed1997

Identification and NH2-terminal amino acid sequences of DnaK and groEL homologues in moderate eubacterial halophiles.

We have identified 2 DnaK and 3 GroEL homologues from moderately halophilic Acinetobacter, Pseudomonas, and Planococcus species by partial purification using an ATP-agarose column and by the analysis and similarity search of these NH2-terminal amino acid sequences. Although these bacteria required 1 to 2M NaCl for growth, these DnaK and GroEL homologues did not require high salt to bind to the ATP column, thus suggesting that these chaperones did not require high salts for their biochemically activities.

Acinetobacter↗
PubMed1997

Chronic effects of methylmercury in rats. II. Pathological aspects.

Chronic effects of methylmercury (MeHg) were examined pathologically in male Wistar rats fed on diet containing 0, 1 or 5 ppm Hg (as MeHg) for two years. Organs including the central nervous tissues were examined histopathologically using hematoxylin and eosin (H & E), Klüver-Barrera (KB), PAS or phenol-congo red stains. The peripheral nerve system tissues were also examined, using H & E and trichrome stains. Furthermore, immunoglobulins of renal specimens were demonstrated by direct immunofluorescence microscopy. Localization of mercury in the paraffin-embedded sections of the nervous tissue, kidney, liver, pancreas, spleen and testis was demonstrable by the photoemulsion histochemical method. In the 5 ppm group, mercury was readily detectable in tissues of the rats exposed for one year, one and half years, two years and two and half years. Mercury was detected in the cells of the brain such as neurons, neuroglial cells, and phagocytes, and also in most organs, particularly in the epithelium of renal tubules, liver cells, myocardium, in the macrophages of pancreas, spleen and testis. In the 1 ppm group, mercury was detectable in the epithelium of renal tubules and liver cells. Fibrosis of the glomeruli was found in the rat group given a high dose of methylmercury with all experimental methods. Granular IgG, IgM and C3 deposits were demonstrated in the glomeruli by direct immunofluorescence microscopy. The etiology of the pathological changes of glomeruli was suspected to be autoimmune glomerulopathy due to inorganic mercury filtration for a long time. It was difficult to determine the clinical signs and symptoms and pathological changes in the nervous system in spite of the deposition of mercury in the brain.

Administration, Oral↗
PubMed1997

Usefulness of elastica-van Gieson stain for the pathomorphological diagnosis of a cutaneous electric mark--a fatal electrocution case during arc welding.

Identification of an electric mark on a body is required for a precise diagnosis of electrocution at the time of forensic autopsy. We applied Elastica-van Gieson (EVG) stain as a means of obtaining the pathomorphological diagnosis of a cutaneous electric mark in relation to a fatal electrocution case. Using EVG stain, the characteristic findings of electric marks, such as elongation of basal-cell nuclei and vacuolation of cells within the epidermis, were clearly observed, while in addition, disarrangement of elastic fibers in the connective tissues within the dermis was also demonstrated. EVG staining was considered to be useful in enabling pathomorphological observations of a cutaneous electric mark to be made.

Accidents, Occupational↗
PubMed1997

[A case of complete remission of gastric endocrine cell carcinoma with multiple bone metastasis by combination chemotherapy and high-dose chemotherapy with autologous peripheral blood stem cell transplantation].

A 31-year-old man was admitted to our hospital complaining of epigastric discomfort and severe lumbago. An upper gastrointestinal endoscopy revealed several submucosallike tumors. Histologic examination of biopsy specimens confirmed the presence of endocrine cell carcinoma. Gallium scintigraphy and CT revealed multiple bone metastasis. He was treated with 6 cycles of combination chemotherapy consisting of CDDP, etoposide, CPA, EPI and VCR. Both gastric tumors and bone metastasis completely disappeared. After 7 cycles of the chemotherapy, he was treated with HDCT with PBSCT. There was no severe complication. This result suggested that the combination of conventional chemotherapy and HDCT with PBSCT was useful in cancer patients with poor prognoses, such as advanced gastric endocrine cell carcinoma.

Adult↗
PubMed1997

Plasma concentrations of antipsychotic drugs in psychiatric inpatients.

In current psychiatric therapy, two or more kinds of antipsychotic drugs are usually prescribed in Japan. However, there are few data on the therapeutic plasma concentrations of antipsychotic drugs or on the correlation between the daily dose and the plasma concentration, in cases where several antipsychotic drugs had been prescribed for each patient. We measured the therapeutic plasma concentrations of 9 antipsychotic drugs in 24 psychiatric inpatients during a 6-month period. They were treated with fixed dosages of antipsychotic drugs. Plasma samples were collected early in the morning once a month, and the concentrations of antipsychotic drugs were determined by gas chromatography with nitrogen phosphorus detection, high-performance liquid chromatography (HPLC) with fluorescence detection and HPLC with UV detection. The plasma levels of chlorpromazine, levomepromazine, thioridazine, haloperidol, bromperidol, zotepine, oxypertine, sulpiride and sultopride were 21.8-92.4, 31.7-156, 101-203, 16.4-56.2, 2.72-11.7, 13.6-84.0, 29.9-80.4, 70.1-1,120 and 35.7-2,990 ng/ml, respectively. A linear correlation between the daily dose and the plasma concentration was noted for sultopride, levomepromazine, sulpiride, haloperidol, chlorpromazine and zotepine.

Adult↗