Biomedical subjects

H Yamada

Publications and source records attributed to H Yamada.

At least 19 recordsLinked to original sources

PubMed2006

Increase in transforming growth factor-beta in the brain during infection is related to fever, not depression of spontaneous motor activity.

When viral infection occurs, this information is transmitted to the brain, and symptoms such as fever and tiredness are induced. One of the causes of these symptoms is the secretion of proinflammatory cytokines in blood and the brain. In this study, the i.p. administration of polyinosinic:polycytidylic acid (poly I:C), a synthetic double-stranded RNA, to rats was used as an infection model. Poly I:C decreased spontaneous motor activity (SMA) 2 h after i.p. administration, and this decrease was maintained thereafter. The concentration of active transforming growth factor-beta (TGF-beta) in cerebrospinal fluid (CSF) increased 1 h after the administration. This increase occurred earlier than those in the concentrations of other proinflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), in serum. The intracisternal administration of an anti-TGF-beta antibody partially inhibited fever induced by poly I:C administration; however, this treatment did not affect the decrease in SMA. Furthermore, intracisternal administration of TGF-beta raised the body temperature. These results indicate that TGF-beta in the brain, which was increased by poly I:C administration, is associated with fever but not with a decrease in SMA.

Animals↗

PubMed2006

SIRT2, a tubulin deacetylase, acts to block the entry to chromosome condensation in response to mitotic stress.

We previously identified SIRT2, an nicotinamide adenine dinucleotide (NAD)-dependent tubulin deacetylase, as a protein downregulated in gliomas and glioma cell lines, which are characterized by aneuploidy. Other studies reported SIRT2 to be involved in mitotic progression in the normal cell cycle. We herein investigated whether SIRT2 functions in the mitotic checkpoint in response to mitotic stress caused by microtubule poisons. By monitoring chromosome condensation, the exogenously expressed SIRT2 was found to block the entry to chromosome condensation and subsequent hyperploid cell formation in glioma cell lines with a persistence of the cyclin B/cdc2 activity in response to mitotic stress. SIRT2 is thus a novel mitotic checkpoint protein that functions in the early metaphase to prevent chromosomal instability (CIN), characteristics previously reported for the CHFR protein. We further found that histone deacetylation, but not the aberrant DNA methylation of SIRT2 5'untranslated region is involved in the downregulation of SIRT2. Although SIRT2 is normally exclusively located in the cytoplasm, the rapid accumulation of SIRT2 in the nucleus was observed after treatment with a nuclear export inhibitor, leptomycin B and ionizing radiation in normal human fibroblasts, suggesting that nucleo-cytoplasmic shuttling regulates the SIRT2 function. Collectively, our results suggest that the further study of SIRT2 may thus provide new insights into the relationships among CIN, epigenetic regulation and tumorigenesis.

Cell Line, Tumor↗

PubMed2006

Sendai virus infection up-regulates trypsin I and matrix metalloproteinase-9, triggering viral multiplication and matrix degradation in rat lungs and lung L2 cells.

To elucidate the virus-host cell interaction, we analyzed quantitatively the expression of various cellular proteases and tumor necrosis factor-alpha (TNF-alpha) after Sendai virus infection in rat lungs and lung L2 cells. After infection, TNF-alpha mRNA levels increased rapidly to a peak on day one, and then trypsin I and matrix metalloproteinase (MMP)-9, but not MMP-2, were significantly up-regulated with a peak on day 2 in vivo. These up-regulations were confirmed in L2 cells. Up-regulation of proMMP-9 and its active convertase trypsin I seems to synergistically enhance virus multiplication and the destruction of lung matrix, resulting in the progression of pneumonia.

Animals↗

PubMed2006

Stimulating effect of Japanese herbal (kampo) medicine, hochuekkito on upper respiratory mucosal immune system.

Japanese herbal (Kampo) medicine, Hochuekkito (Bu-Zhong-Yi-Qi-Tang in Chinese, TJ-41) and Juzentaihoto (Shi-Quan-Da-Bu-Tang in Chinese, TJ-48) are well-known Kampo formulas used as tonic. Although these medicines have separately been applied to the patients clinically depending on their symptoms, the differences of the pharmacological activities for these medicines have not been fully understood. TJ-48 and TJ-41 were compared for their effects on antibody response in upper respiratory mucosal immune system in vivo. Oral administration of TJ-41 (100 mg kg(-1) per day) to early aged BALB/c mice, which were nasally sensitized with influenza hemagglutinin vaccine, significantly enhanced influenza virus-specific IgA and IgG antibody titers in nasal cavity and sera, respectively. However, oral administration of TJ-48 (100 mg kg(-1) per day) failed to show the enhancing activity. TJ-41 increased not only influenza virus-specific IgA antibody titer but also total IgA antibody titer in nasal cavity. The stimulating activity of TJ-41 disappeared after treatment with methotrexate. The present study strongly suggests that TJ-41 can stimulate the mucosal immune system of upper respiratory tract, and results in enhancement of antigen-specific antibody response in upper respiratory mucosal and systemic immune systems.

Journal Article↗

PubMed2006

Theory and characteristics of transition radiation emitted by low-energy storage-ring synchrotrons for use in X-ray lithography.

Existing theory is developed further for description of transition radiation (TR) emitted by low-energy storage-ring synchrotrons. It takes into account the fact that the dielectric constant of the TR target material is a complex function, introduces an expression for the number of passes of an injected electron through the target, and accounts more precisely for the absorption of TR. It is shown that the consideration of the complexity of the dielectric constant results in notable changes of the TR spectrum for emitted photons with energies close to the ionization energies of the target material. Since such TR is used mostly for performing X-ray lithography (XRL), the sensitivity of the photoresist used in XRL is formulated. Maximization of this resist sensitivity can be used for designing optimum targets for XRL. Study of the transmission of TR through a commonly used XRL mask, and its partial absorption in a common photoresist, illustrates that TR emission with E = [490, 1860] eV is most useful for performing such XRL, while E approximately equal to 1 keV is best. It is shown that, for a particular target material, a target consisting of only one foil emits the most TR energy. Optimization of an Al target, based on maximization of the resist sensitivity, indicates that a target containing one Al foil with a thickness of about 200 nm would be best for performing XRL by our low-energy storage-ring synchrotron MIRRORCLE-20SX.

Computer Simulation↗

PubMed2006

Clinical outcome and risk factors for recurrence in borderline ovarian tumours.

We investigated the long-term prognosis of borderline ovarian tumours and determined risk factors for recurrence. One hundred and twenty-one borderline ovarian tumours treated between 1994 and 2003 at the participating institutions in the Tohoku Gynecologic Cancer Unit were retrospectively investigated for clinical stage, histopathological subtype, surgical technique, postoperative chemotherapy, the presence or absence of recurrence, and prognosis. The median follow-up period was 57 months (1-126 months). One hundred and nine cases (90.6%) were at clinical stage I. The histopathological subtypes consisted of 91 cases of mucinous tumour (75.2%), 27 cases of serous tumour (22.3%), and three cases of endometrioid tumour. Conservative surgery was used in 53 cases (43.8%), radical surgery in 68 cases (56.2%), a staging laparotomy in 43 cases (35.5%), and postoperative adjuvant therapy in 30 cases (24.8%). Recurrence was found in eight cases, but no tumour-related deaths were reported. Although no significant difference in disease-free survival rate was seen between different clinical stages, the difference in disease-free survival rate between serous and non-serous (mucinous and endometrioid) types was significant (P<0.05). The 10-year disease-free survival rate was 89.1% for the radical surgery group and 57.4% for the conservative surgery group -- this difference was significant (P<0.05). In the conservative surgery group, cystectomy and serous tumour were independent risk factors for recurrence. Although recurrence was observed, the long-term prognosis of borderline ovarian tumour was favourable, without tumour-related deaths. Considering the favourable prognosis, conservative surgery can be chosen as far as the patient has a non-serous tumour and receive adnexectomy. However, in cases of serous type and/or receiving cystectomy special care should be given as relative risk rates of recurrence elevate by 2-4-folds.

Adult↗

PubMed2006

Intravenous cyclophosphamide therapy for progressive interstitial pneumonia in patients with polymyositis/dermatomyositis.

OBJECTIVES: To study the efficacy and safety of monthly intravenous pulse cyclophosphamide (IVCYC) therapy for progressive interstitial pneumonia in polymyositis/dermatomyositis (PM/DM). METHODS: Seventeen patients with PM/DM/amyopathic DM (mean age 51.4 +/- 10.4, mean follow-up 32 months) who received IVCYC for progressive interstitial pneumonia between August 1993 and October 2002 were studied. Nine patients had failed to respond to previous treatment with high-dose steroid and/or immunosuppressant. Cyclophosphamide (300-800 mg/m2) was given at least six times every 4 weeks. Oral prednisolone (0.5-1 mg/kg/day) was administered for the first 2 weeks and was gradually tapered. Response to treatment was evaluated based on the degree of exertional dyspnea, pulmonary function test and high-resolution computed tomography (HRCT). RESULTS: Eleven of 17 patients showed improvement in their dyspnea; six out of seven patients who had required oxygen treatment before IVCYC no longer did so after IVCYC. Eight of 17 patients had >or=10% improvement of vital capacity (VC)% and 9/17 had >or=10 point reduction in their HRCT score. Twelve patients had exhibited at least one result. Two patients with anti-Jo-1 antibodies showed a flare-up of interstitial pneumonia or myositis. After the IVCYC therapy, mean VC% improved by 15% (from 68 to 83%, P = 0.0034). The extent of abnormal lesions in HRCT was reduced from 24 to 13% (P = 0.0055). There was neither death nor severe toxicities observed. CONCLUSIONS: In this open-label study, IVCYC improved symptoms, pulmonary function tests and HRCT findings in patients with PM/DM. Longitudinal controlled studies are required to further confirm the efficacy of IVCYC.

Adult↗

PubMed2006

Phase I/II study of S-1 combined with irinotecan for metastatic advanced gastric cancer.

A dose-escalation study of irinotecan (CPT-11) combined with S-1, an oral dihydropyrimidine dehydrogenase inhibitory fluoropyrimidine, was performed to determine the maximum-tolerated dose (MTD), recommended dose (RD), dose-limiting toxicities (DLTs), and objective response rate (RR) in advanced gastric cancer (AGC). S-1 was administered orally at 80 mg m-2 day-1 from day 1 to 14 of a 28-day cycle and CPT-11 was given intravenously on day 1 and 8 at an initial dose of 70 mg m-2 day-1, stepping up to 100 mg m-2. The treatment was repeated every 4 weeks, unless disease progression was observed. In the phase I portion, the MTD of CPT-11 was presumed to be 100 mg m-2, because 66.6% of patients (two of three) developed DLTs. All three patients at the initial RD of CPT-11 (90 mg m-2) experienced grade 4 haematological or grade 3 nonhaematological toxicities at second course, followed by the dose reduction of CPT-11 from the third course. Considering safety and the ability to continue treatment, the final RD was determined to be 80 mg m-2. In the phase II portion, 42 patients including seven patients in the final RD phase I portion were evaluated. The median treatment course was five (range: 1-13). The incidences of severe (grade 3-4) haematological and nonhaematological toxicities were 19 and 10%, respectively, but all were manageable. The RR was 62% (26 of 42, 95% confidence interval: 47.2-76.6%), and the median survival time was 444 days. Our phase I/II trial showed S-1 combined with CPT-11 is effective for AGC and is well tolerated, with acceptable toxicity.

Administration, Oral↗

PubMed2006

Slow transition of energy transport in high-temperature plasmas.

A new slow transition process for energy transport in magnetically confined plasmas is reported. The slow transition is characterized by the change between two metastable transport conditions characterized by a weak and a strong electron temperature (Te) dependence of normalized heat flux. These two branches are found to merge at the critical gradient. In metastable transport, the derivative of normalized heat flux to the Te gradient, [EQUATION: SEE TEXT], is positive, while it becomes negative during the transition phase. The time for the transition increases as the normalized Te gradient is increased and exceeds the transport time scale characterized by the global energy confinement time.

Journal Article↗

PubMed2006

G-Quadruplex stabilization by telomestatin induces TRF2 protein dissociation from telomeres and anaphase bridge formation accompanied by loss of the 3' telomeric overhang in cancer cells.

Inhibition of telomerase activity by telomerase inhibitors induces a gradual loss of telomeres, and this in turn causes cancer cells to enter to a crisis stage. Here, we report the telomerase inhibitor telomestatin, which is known to stabilize G-quadruplex structures at 3' single-stranded telomeric overhangs (G-tails), rapidly dissociates TRF2 from telomeres in cancer cells within a week, when given at a concentration that does not cause normal cells to die. The G-tails were dramatically reduced upon short-term treatment with the drug in cancer cell lines, but not in normal fibroblasts and epithelial cells. In addition, telomestatin also induced anaphase bridge formation in cancer cell lines. These effects of telomestatin were similar to those of dominant negative TRF2, which also causes a prompt loss of the telomeric G-tails and induces an anaphase bridge. These results indicate that telomestatin exerts its anticancer effect not only through inhibiting telomere elongation, but also by rapidly disrupting the capping function at the very ends of telomeres. Unlike conventional telomerase inhibitors that require long-term treatments, the G-quadruplex stabilizer telomestatin induced prompt cell death, and it was selectively effective in cancer cells. This study also identifies the TRF2 protein as a therapeutic target for treating many types of cancer which have the TRF2 protein at caps of the telomere DNA of each chromosome.

Anaphase↗

PubMed2006

In vivo protein transduction to the CNS.

Proteins and peptides are useful research and therapeutic tools, however applications are limited because delivery to the desired location is not easily achievable. There are two hurdles in protein/peptide delivery to the brain: the blood-brain barrier and intracellular penetration. Penetration to both brain and the intracellular space can be achieved by adjusting hydrophilicity, and small molecule pharmacological agents have been successfully developed using this approach. But with proteins and peptides, it is difficult to modify the hydrophilicity without influencing biological functions. Trans-acting factor protein from the human immunodeficiency virus contains a highly conserved cationic peptide sequence necessary for transduction across the cell membrane. While trans-acting factor peptide has been used for in vitro protein transduction, its in vivo application is very limited because it is rapidly degraded by proteolysis. Polyethylenimine is a chemically synthesized small molecule cationization agent; the charge density is greater than a peptide-based cationic cluster such as trans-acting factor, and it is resistant to proteolysis in vivo. We first tested intracellular protein transduction following direct brain injection in mice using polyethylenimine-conjugated green fluorescence protein and beta-galactosidase (molecular weights 29 and 540 kDa, respectively). Polyethylenimine-conjugates penetrated to the intracellular space immediately surrounding the injection site within one hour. We further tested polyethylenimine-mediated protein transduction following intranasal administration, which bypasses the blood-brain barrier. Polyethylenimine-conjugates in pH 7.5 solution did not reach the brain, probably because the polyethylenimine-conjugates penetrated into the intracellular space where first exposed to the tissue, i.e. at the nasal mucosae. We temporarily reduced the electrostatic interaction between cationized polyethylenimine-conjugates and cellular surfaces by adjusting the pH to 4.5; solution rapidly reached the brain and penetrated to the intracellular space. This study suggests that polyethylenimine is a useful protein transduction agent in the brain in vivo, and adjusting cationic charge interaction can determine the extent of brain penetration.

Administration, Intranasal↗

PubMed2006

Antidepressant-like activity of a Kampo (Japanese herbal) medicine, Koso-san (Xiang-Su-San), and its mode of action via the hypothalamic-pituitary-adrenal axis.

Koso-san (Xiang-Su-San in Chinese), a Kampo (Japanese herbal) medicine, is used clinically in East Asia for the treatment of depression-like symptoms associated with the initial stage of the common cold, allergic urticaria due to food ingestion, irritable bowel syndrome, chronic fatigue syndrome, insomnia, and autonomic imbalance. However, the antidepressant-like activity of Koso-san has never been evaluated scientifically. In this study, ddY mice subjected to a combination of forced swimming and chronic mild stresses were termed depression-like model mice. The degree of the depression-like state was measured by the animal's duration of immobility using the forced swimming test (FST). Oral administration of Koso-san (1.0 g/kg/body wt./day, 9 days) significantly shortened the duration of immobility of the depression-like model mice in the FST; however, locomotor activity was not affected. Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis plays an important role in the pathophysiology of depression. Levels of corticotropin-releasing hormone mRNA expression in the hypothalamus and proopiomelanocortin mRNA expression in the pituitary were significantly increased, and glucocorticoid receptor protein expression in the hypothalamus paraventricular nucleus was downregulated in the depression-like model mice. However, Koso-san ameliorated these alterations to the normal conditions. The results of this study suggest that Koso-san shows the antidepressant-like effect through suppressing the hyperactivity of the HPA axis in depression-like model mice.

Animals↗

PubMed2006

Morphology control of poly(vinylidene fluoride) thin film made with electrospray.

Thin polymer films of poly(vinylidene fluoride) were prepared with electrospray. Effects of solvent, initial spray concentration, temperature, solution conductivity, and polymer size on the film morphology were studied with AFM. The two main factors controlling polymer film morphology are the droplet size of the spray and the viscosity of the solution at deposition. These factors determine the flow of the polymer-solvent mixture over the substrate, the density of the film, and its smoothness. The solvent is a key parameter of the entire process. It affects spray stability, polymer solubility, droplet size of the spray, and viscosity of the solution at deposition. Solvents with a low vapor pressure provide a wider window for optimization of other parameters and are therefore preferred over solvents with high vapor pressure. The viscosity at deposition is mainly controlled with the initial spray concentration, polymer size, temperature, and droplet size. The droplet size is best controlled by the conductivity of the solution and the flow rate of the spray.

Journal Article↗

PubMed2006

The presence of natural human antibodies reactive against pharmacologically active pectic polysaccharides from herbal medicines.

Direct ELISA was performed using normal human sera and human colostrum, to analyse the presence of antibodies which react with pharmacologically active pectic polysaccharides isolated from plants used in traditional Japanese herbal (Kampo) medicine. All sera and colostrum were shown to contain IgM, IgG, IgA and secretory IgA class antibodies which react with the active pectic polysaccharides to different degrees. The reacting IgG antibody in normal human serum recognized the ramified regions (rhamnogalacturonan core with carbohydrate side-chains) of the pharmacologically active pectic polysaccharides as the active sites for complement-activating activity. Correlation analysis indicated that a significant and positive correlation was observed between reactivity with the reacting antibody of IgG class and the degree of complement-activating activity of the active polysaccharides. The reacting IgG class antibody, which was purified from normal human serum by affinity chromatography on bupleuran 2IIc (a pharmacologically active pectic polysaccharide from the roots of Bupleurum falcatum)-immobilized Sepharose, showed cross-reactivity not only with some other pharmacologically active pectic polysaccharides from other medicinal herbs but also with autoantigens such as single-strand DNA, myosin and tublin from mammals.

Angelica↗

PubMed2006

Screening of Thai medicinal plant extracts and their active constituents for in vitro antimalarial activity.

To discover antimalarial substances from plants cultivated in Thailand 80%-EtOH extracts from selected plants were screened for in vitro antimalarial activity against the drug resistant K1 strain of Plasmodium falciparum. In total, 86 Thai medicinal plant samples representing 48 species from 35 genera in 16 families were screened and two species (Polyalthia viridis and Goniothalamus marcanii) were found to show notable antimalarial activity (IC50: 10.0 and 6.3 microg/mL). Marcanine A and 16-hydroxycleroda-3,13(14)Z-dien-15,16-olide were identified as the respective major active constituents in P. viridis and G. marcanii, respectively.

Animals↗

PubMed2006

Antiproliferative and apoptotic effects of butyrolactone lignans from Arctium lappa on leukemic cells.

In the course of screening for pharmacologically active substances from extracts of crude drugs used traditionally in Sino-Japanese herbal medicines, it was found that the 70 % ethanol extract from the fruits of Arctium lappa L. (Compositae) showed potent antiproliferative activity against B cell hybridoma cell, MH60. By bioassay-guided purification, a new lignan, (+)-7,8-didehydroarctigenin, together with the known lignans (-)-arctigenin and (-)-matairesinol were isolated as the active ingredients from an aqueous ethanolic extract of the fruits of A. lappa. Of these active compounds, (-)-arctigenin showed the most potent antiproliferative activity against MH60 cells (IC (50) : 1.0 microM), and the activity was suggested to be due to apoptosis.

Antineoplastic Agents, Phytogenic↗

PubMed2006

Role of Th1-stimulating cytokines in bacillus Calmette-Guérin (BCG)-induced macrophage cytotoxicity against mouse bladder cancer MBT-2 cells.

Previously, we have demonstrated that macrophages exhibited cytotoxicity toward mouse bladder cancer MBT-2 cells upon bacille Calmette-Guérin (BCG) stimulation. In this study, we have investigated the role of Th1-stimulating cytokines in BCG-induced macrophage cytotoxicity. Thioglycollate-elicited peritoneal exudate cells (PECs) were used as a conventional source for macrophages and the induction of PEC effector functions (cytolytic activity and cytokine production) by BCG was evaluated in vitro. The BCG-activated PECs showed potent cytotoxicity and killed MBT-2 cells in a dose-dependent manner. Depletion of T cells, natural killer (NK) cells, or both, in PEC preparations exhibited a marginal or small reduction of MBT-2 cell killing, suggesting that macrophages played a primary role in PEC cytotoxicity. Transwell assays indicated that the maximal PEC cytotoxicity required both direct cell-cell contact and soluble factors such as interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha. Neutralizing endogenous cytokines interleukin (IL)-12, IL-18, IFN-gamma or TNF-alpha reduced PEC cytotoxicity by 38%, 22%, 15% and 94%, respectively. Supplementation of BCG with recombinant (r)IL-2, rIL-12 or rIL-18 increased PEC cytotoxicity by approximately twofold. Compared with control BCG for PEC stimulation, rBCGs expressing IL-2 or IL-18 showed enhanced MBT-2 cell killing by PECs. Increased cytokine production (IFN-gamma, TNF-alpha and IL-6) was also observed in rBCG-stimulated PEC cultures. Taken together, these results suggest that Th1-stimulating cytokines play an important role in BCG-induced macrophage cytotoxicity and that combination of BCG with selected Th1-stimulating cytokines, either supplemented or expressed by BCG, may enhance the effect of BCG in the treatment of bladder cancer patients.

Animals↗

PubMed2006

Propofol acts at the sigma-1 receptor and inhibits pentazocine-induced c-Fos expression in the mouse posterior cingulate and retrosplenial cortices.

BACKGROUND: The sigma-1 receptor is functionally linked with psychotomimetic effects of various drugs. A sigma-1 receptor agonist enhances bradykinin-induced intracellular Ca(2+) concentration ([Ca(2+)]i) increase and induces c-Fos expression in a part of the brain. The aim of this study was to investigate the effects of several intravenous anaesthetics on the sigma-1 receptor. METHODS: First, using Wistar rat brains, (+)[(3)H]SKF-10,047, a selective sigma-1 receptor agonist was displaced by propofol, dexmedetomidine, droperidol, and thiopental. Second, Fura-2 loaded NG-108 cells were incubated with (+)pentazocine, a selective sigma-1 receptor agonist, and propofol and then its fluorescence was observed after stimulation with bradykinin. Third, male ICR mice received Intrafat or propofol intraperitoneally (i.p.), followed by pentazocine i.p. Brain slices were prepared and Fos-like immunoreactivity was detected using an immunohistochemical method. results: Propofol, droperidol, and dexmedetomidine displaced (+)[(3)H]SKF-10,047 binding in a concentration-dependent manner with Ki50s of 10.2 +/- 0.6, 0.17 +/- 0.03, 5.73 +/- 1.2 microM, respectively. Thiopental sodium was practically ineffective. Propofol produced a statistically significant reduction in the maximal binding capacity (Bmax) but did not affect the dissociation constant (K(d)). (+)Pentazocine significantly enhanced bradykinin-induced [Ca(2+)]i increases, but propofol did not affect it. Pentazocine induced marked Fos-LI positive cells in the posterior cingulate and retrosplenial cortices (PC/RS), which was significantly reduced by propofol. CONCLUSIONS: These results suggest that propofol may be a sigma-1 receptor antagonist, and that various effects of propofol on the brain may be mediated, at least partly, by the sigma-1 receptor.

Analgesics, Opioid↗