Biomedical subjects

Hiroyuki Tanaka

Publications and source records attributed to Hiroyuki Tanaka.

At least 127 records · Page 7Linked to original sources

PubMed2004

Endocannabinoid system modulates relapse to methamphetamine seeking: possible mediation by the arachidonic acid cascade.

We clarified the modulating action of the endocannabinoid system, and its possible mediation by the arachidonic acid cascade, on the reinstatement of methamphetamine (METH)-seeking behavior, using the intravenous self-administration paradigm in rats. Following 12 days of self-administration of METH, the replacement of METH with saline resulted in a gradual decrease in lever press responses (extinction). Under extinction conditions, METH-priming or re-exposure to cues previously paired with METH infusion markedly increased the responses (reinstatement of drug-seeking). The cannabinoid CB1 receptor antagonist, SR141716A, blocked this behavior. Although the cannabinoid agonist, Delta8-tetrahydrocannabinol (THC), had no effects by itself, coadministration of the agonist and METH at small doses reinstated the drug-seeking behavior. THC attenuated the effects of the reinstatement-inducing dose of METH, but enhanced the effect of cues. Either given repeatedly during the extinction or singly, 24 h before the first METH-priming or cues challenge, THC suppressed the reinstatement. In another set of experiments, we found that diclofenac, a cyclooxygenase inhibitor, also attenuated the reinstatement induced by exposure to cues or drug-priming. These results suggest that the endocannabinoid system, through possible mediation by the arachidonic acid cascade, serves as a modulator of the reinstating effects of METH-priming and cues. Extending the current view on the treatment of drug dependence, these results indicate that endocannabinoid-activating substances as well as cyclooxygenase inhibitors may be promising as antirelapse agents.

Amphetamine-Related Disorders↗

PubMed2004

Regeneration of injured intestinal mucosa is impaired in hepatocyte growth factor activator-deficient mice.

BACKGROUND AND AIMS: Hepatocyte growth factor activator (HGFA) is a serum proteinase that specifically converts an inactive single-chain form of hepatocyte growth factor (HGF) into an active 2-chain form. HGFA is produced in its precursor form and then activated in injured tissues. To address the precise role of HGFA and to investigate the mechanisms of HGF activation in injured tissues, we generated mice deficient in HGFA. METHODS: HGFA-deficient mice were generated using targeted gene disruption. The regenerating process of intestinal mucosa damaged by oral administration of dextran sodium sulfate (DSS) or by rectal administration of acetic acid was examined in both HGFA-deficient and control mice. HGF processing activity was analyzed using Western blotting and an HGF activation assay. RESULTS: Homozygous mutant mice were viable and fertile without obvious abnormalities. When mice were treated with 3% DSS in drinking water for 6 days followed by distilled water without DSS, 72% of HGFA-deficient mice died through day 12 while 75% of control mice survived injury. Similar results were also observed in the acetic acid-induced intestinal injury; the survival rate was 36.6% in HGFA-deficient mice and 84.2% in control mice. In HGFA-deficient mice, the injured mucosa was not sufficiently covered by regenerated epithelium and the activation of HGF was impaired in the injured colon. CONCLUSIONS: These results indicate that HGFA is required for repair of injured intestinal mucosa but is not essential for normal development during embryogenesis or after birth.

Animals↗

PubMed2004

Resveratrol inhibits the release of mediators from bone marrow-derived mouse mast cells in vitro.

Resveratrol is a natural phytoalexin occurring in grapes, vines and peanuts and possesses both antitumor and antioxidation capabilities. Its chemoprotective actions are attributed partially to its anti-inflammation effect. The present study is aimed at checking the inhibitory actions of resveratrol on the release of mediators from bone marrow-derived mouse mast cells (BMMC) in vitro. Mast cells were prepared by isolating bone marrow cells from intact mice femora and culturing them for 4 weeks in the presence of IL-3 and FCS. The release reaction was triggered by IgE or calcium ionophore (A23187). Mediated by IgE, the release of histamine and tumor necrosis factor-alpha was significantly inhibited by resveratrol at a concentration of 100 microM; IgE-mediated release of leukotrienes and prostaglandin D (2) was also strongly suppressed at concentrations of 100 and 10 microM. Also, A23187-mediated release of histamine and leukotrienes release was strongly reduced by resveratrol at concentrations of 100 and 10 microM, respectively. Resveratrol exhibited its behavior without a significant cytotoxic activity against mast cells. In conclusion, resveratrol is a potent non-selective inhibitor of mediator release from activated mast cells and deserves further investigation of its biological modulations.

Animals↗

PubMed2004

Quantitative structure-activity relationship for the cleavage of C3/C4-substituted catechols by a prototypal extradiol catechol dioxygenase with broad substrate specificity.

Catechol 2,3-dioxygenase [EC 1.13.11.2] from Pseudomonas putida mt-2 (Mpc) catalyzes the extradiol cleavage of catechol to produce 2-hydroxymuconate semialdehyde. The K(m) values for the catecholic substrate (K(mA)) and O(2) (K(mO2)), and catalytic constants (k(cat)) were kinetically determined for eight C3/C4-substituted catechols at 25 degrees C and pH 6.5 or 7.5. The first pK(a) values (pK(1)) were determined for eleven catechols (pK(1) = 7.26-9.47), correlated with Hammett substituent constants, and electron-withdrawing substituents significantly stabilized the monoanionic species of free catechols. Mpc preferred catechols with non-ionic substituents at the C3 or C4 position. 3-Phenylcatechol, a biphenyl, was cleaved, while 4-tert-butylcatechol was not. The logarithm of k(cat)/K(mA) (substrate specificity constant) exhibited a good linear correlation with pK(1), with the exception of those for 4-halocatechols. The logarithm of k(cat)/K(mO2) showed a good linear correlation with pK(1), with the exception of that of 3-phenylcatechol. These results demonstrate that catechol binding to the Mpc active site, the following O(2) binding, and the activation of the bound O(2) are all sensitive to electronic effects of the substituents. However, k(cat) did not correlate significantly with pK(1). The present study distinguishes clearly between the electronic and the steric effects of catecholic substrates in the reactivity of Mpc, and provides important insight into the mechanistic basis for a vast range of substrate specificities of extradiol dioxygenases.

Binding Sites↗

PubMed2004

Expression and function of Ets-1 during experimental acute renal failure in rats.

The Ets family of transcription factors is defined by a conserved DNA-binding Ets domain that forms a winged helix-turn-helix structure motif. The Ets family is involved in a diverse array of biologic functions, including cellular growth, migration, and differentiation. The hypothesis in this study was that Ets-1 is re-expressed during regeneration after acute renal failure (ARF) and plays a key role in the transcriptional regulation of cyclin D1 and the cell cycle progression in renal tubular cells. For clarifying the significance of Ets-1 in ARF, a rat ARF model in vivo and LLC-PK1 cells as an in vitro model were used. After the left rat renal artery was clamped for 1 h, the whole kidney homogenate was examined and total RNA was extracted at 6, 12, 24, 48, and 72 h after reperfusion by Western blot analysis and real-time reverse transcription-PCR. Ets-1 mRNA and protein expression were strongly increased at 6 to 24 h after the ischemia, respectively. The expression of hypoxia-inducible factor-1alpha was increased dramatically as early as 6 h after ischemia-reperfusion and decreased at 48 and 72 h after ischemia-reperfusion. In the immunohistologic examination, Ets-1 was expressed in the proximal tubules and coexpressed with proliferating cell nuclear antigen (PCNA). Furthermore, overexpression of Ets-1 promoted the cell cycle and increased the promoter activity and protein expression of cyclin D1 in LLC-PK1 cells. Ets-1 promoter activity increased between 3 and 6 h in hypoxia, and hypoxia also induced changes in the Ets-1 protein level in LLC-PK1 cells. The Ets-1 induction by hypoxia was abolished by the transfection of dominant-negative hypoxia-inducible factor-1alpha. A gel shift assay demonstrated that Ets-1 binds to the ets-1 binding site of the cyclin D1 promoter in the ischemia-reperfusion condition. Overexpression of Ets-1 did not significantly change the caspase 3 activity or the value of cell death ELISA in LLC-PK1 cells. Taken together, these data suggest that Ets-1 plays a key role in the cell-cycle progression of renal tubules in ARF. The Ets-1 pathway may regulate the transcription of cyclin D1 and control the regeneration of renal tubules in ARF.

Acute Kidney Injury↗

PubMed2004

Paradoxically enhanced immunoreactivity of hepatocyte growth factor activator inhibitor type 1 (HAI-1) in cancer cells at the invasion front.

We have previously demonstrated significantly decreased immunoreactivity of hepatocyte growth factor activator inhibitor type 1 (HAI-1), an integral membrane protein that exhibits potent inhibitory activity against hepatocyte growth factor activator (HGFA) and matriptase, in colorectal adenocarcinomas. In this report, we describe further detailed analysis of HAI-1 expression in colorectal adenocarcinoma by using three kinds of anti-HAI-1 antibodies, each of which recognizes a distinct epitope of the HAI-1 molecule, and also by in-situ hybridization for HAI-1 mRNA. The results indicated that the decreased immunoreactivity of HAI-1 in colorectal carcinoma cells is largely a result of enhanced ectodomain shedding of HAI-1 in these cells. In contrast, immunoreactivity of mature membrane-form HAI-1 was paradoxically en-hanced in cancer cells at the invasion front, showing intense cell-stroma interactions and/or sprouting invasion. This finding indicates that these invading cells showed decreased ectodomain shedding of HAI-1 and consequently might require the existence of the membrane-form HAI-1. Of particular interest was the observation of a possible inverse correlation between paradoxical up-regulation of membrane-form HAI-1 expression and membrane-associated E-cadherin in these cells. These membrane-form HAI-1-positive sprouting cancer cells were also negative for MIB-1 immunohistochemically, indicating a low-proliferating population. All these results suggest that HAI-1 may mediate diverse functions in regard to the progression of colorectal carcinomas, and the immunoreactivity of membrane-form HAI-1 may serve as a marker of invading cancer cells.

Adenocarcinoma↗

PubMed2004

Effect of MX-68 on airway inflammation and hyperresponsiveness in mice and guinea-pigs.

MX-68 is a newly synthesized antifolate, which is a derivative of methotrexate (MTX). In this paper, the effect of MX-68 on allergic airway responses in mice and guinea-pigs was studied. In the first experiment, antigen-induced airway inflammation and airway hyperresponsiveness (AHR) to acetylcholine in mice were examined and compared with the effects of classical antifolate methotrexate and prednisolone. Mice were sensitized with ovalbumin as an antigen and challenged with ovalbumin inhalation three times. After the last inhalation, AHR and airway inflammation were observed. An increase in Th2 cytokines (IL-4 and IL-5) and a decrease in a Th1 cytokine (IFN-gamma) in the bronchoalveolar lavage fluid (BALF), as well as an elevation of the immunoglobulin level in serum, were observed in sensitized mice. Oral administration of MX-68 had no effect on changes of body weight, but prednisolone reduced body weight during the experiment. The antigen-induced AHR and increases in the number of eosinophils and lymphocytes in BALF were significantly inhibited by MX-68. MX-68 interfered with the elevation of IL-4 and IL-5 levels in BALF, but had no effect on the decrease in IFN-gamma. Moreover, MX-68 significantly inhibited the elevation of serum IgE and IgG levels. In the guinea-pig model for bronchial asthma, biphasic increases in airway resistance (immediate asthmatic response, IAR, and late asthmatic response, LAR), as well as accumulated inflammatory cells in BALF, were observed after repeated antigen challenge. These asthmatic responses and inflammatory signs were significantly decreased by administration of MX-68. These results suggest that MX-68 obviously has an anti-inflammatory effect in an animal model of asthma and would be useful clinically for the treatment of bronchial asthma.

2-Aminoadipic Acid↗

PubMed2004

The effect of a newly synthesized indazole compound, TAS-3-124, on experimental autoimmune disease.

The effects of a newly synthesized compound, 6-acetoamido-1-acetyl-1-indazole (TAS-3-124), on autoimmune diseases were studied. We used animal models of collagen-induced arthritis (CIA) in mice and experimental autoimmune encephalomyelitis (EAE) in rats to evaluate the efficacy of TAS-3-124. TAS-3-124 at doses of 100 and 300 mg/kg p.o. inhibited the development of CIA, decreasing the swelling of fore- and hind-limbs and bone destruction in knee joints. This agent also suppressed the delayed type hypersensitivity reaction (DTH) against type II collagen. These effects were confirmed by histopathological examination and measurement of the expression of mRNA of proinflammatory cytokines in the knee joint. In addition, TAS-3-124 at a dose of 300 mg/kg inhibited the development of EAE and the DTH to myelin basic protein (MBP) in rats. Moreover, TAS-3-124 inhibited the production of proinflammatory cytokines including interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 but not T cell derived cytokines in mice. These demonstrate the efficacy of TAS-3-124 against experimental autoimmune disease, probably due to the suppression of the production of proinflammatory cytokines in the pathological lesion.

Acetamides↗

PubMed2004

Establishment of allergic dermatitis in NC/Nga mice as a model for severe atopic dermatitis.

Mite antigen has been suggested to play important roles in the onset and/or development of atopic dermatitis, and mite antigen-induced dermatitis models appear beneficial for the basic study of atopic dermatitis. In the present study therefore, we attempted to establish an allergic dermatitis model in mice using Dermatophagoides farinae crude extract as an antigen. Mite antigen solution at a concentration of 1 or 10 mg/ml was painted 5 times repeatedly at an interval of 7 d onto the ear of NC/Nga or BALB/c mice with or without simultaneous tape-stripping. Apparent biphasic ear swelling was observed after the 4th and 5th antigen applications in both strains of mice treated with 10 mg/ml of antigen solution. Thickening of the epidermis, fibrosis of the dermis, and the accumulation of inflammatory cells were also observed after the 5th application. The inflammatory changes were more evident in NC/Nga mice than in BALB/c mice and potentiated by tape-stripping. The ear swelling was accompanied by increased serum IgE, increased expression of interleukin-4 mRNA and decreased expression of interferon-gamma mRNA in cervical lymph nodes and ears. These results indicate that ear swelling caused by repeated mite antigen application with simultaneous tape-stripping has a Th2-dominant background and that the inflammatory responses are expressed more potently in NC/Nga mice than in BALB/c mice. The dermatitis caused by mite antigen in NC/Nga mice appears to be a useful model for the basic study of atopic dermatitis.

Animals↗

PubMed2004

Development of an assay system for saikosaponin a using anti-saikosaponin a monoclonal antibodies.

For immunization, saikosaponin a (SSa) was conjugated with bovine serum albumin (BSA). The hapten number in an antigen conjugate was determined to be eleven by matrix-assisted laser adsorption/ionization time-of-flight mass spectrometry (MALDI-TOF Mass). Hybridomas secreting monoclonal antibodies (MAb) against SSa were produced by fusing splenocytes immunized with SSa-BSA conjugate and a hypoxanthine-aminopterin-thymidine-sensitive (HAT) mouse myeloma cell line, P3-X63-Ag8-653. A high specific MAb against SSa was selected from hybridomas using enzyme-linked immunosorbent assay (ELISA) analysis. Weak cross-reactivities occurred with saikosaponin c, b(2) and d, which are stereochemical and/or functional isomers of SSa, but no cross-reactivities were observed with other related steroidal glycosides. The full range of the assay extends 26 ng/ml to 1.5 microg/ml of SSa. Good correlation of SSa concentrations in a crude extract of Bupleuri radix between ELISA and HPLC methods was obtained after hydrolysis of acyl saikosaponins by treatment with a mild alkaline solution. The newly established ELISA has been applied for the quantitative assay of SSa in the Bupleuri radix and the Kampo medicines (TCM) prescribed with Bupleuri radix.

Animals↗

PubMed2004

Left ventricular outflow tract obstruction due to anomalous insertion of papillary muscle.

A 56-year-old man who complained of quadrantic hemianopsia was admitted to determine its etiology. Cerebral angiography revealed no organic stenosis. Echocardiography showed clear direct continuity between a hypertrophied anterolateral papillary muscle and the anterior mitral leaflet, and the left ventricular (LV) outflow tract (LVOT) was narrowed by the presence of an accessory papillary muscle. The LVOT obstruction caused an intra-LV pressure overload that resulted in LV concentric hypertrophy. Arrhythmia, such as paroxysmal atrial fibrillation (PAF), was thought to have caused a cerebral embolism. Mitral valve replacement (MVR), septal myectomy, and myectomy of the abnormal papillary muscle were performed, and complete release of the LVOT obstruction was accomplished. Anomalous insertion of papillary muscle is a rare cause of LVOT obstruction. Echocardiography was useful in identifying the papillary muscle malformation, and surgery was completely curative.

Cerebral Infarction↗

PubMed2004

Double primary left ventricular and aortic valve papillary fibroelastoma.

Papillary fibroelastomas of the heart are relatively rare benign tumors and although they can be symptom free, symptoms such as cerebral ischemia and cardiac infarction can be lethal. It is important to diagnose this tumor using echocardiography, because lethal embolisms can be prevented by surgical resection. Recurrence of this tumor has not been reported and multiple tumors are rare. The present report is a case of double primary aortic valve fibroelastoma with aortic regurgitation diagnosed 4 years after surgery for a left ventricular fibroelastoma with mitral valvular disease.

Aortic Valve↗

PubMed2004

Clinical evaluation of recombinant human growth hormone in Noonan syndrome.

The objective of this study was to investigate the effect of administration of recombinant human growth hormone (hGH) in patients with Noonan syndrome. hGH was administered (0.5 IU/kg/week) to 15 patients with Noonan syndrome over a 2 year period. Average patient age prior to therapy was 7.5 +/- 2.5 (mean +/- SD) yr, the height SD score was -2.8 +/- 0.7, and the pretreatment height velocity and bone age were 4.8 +/- 1.0 cm/yr and 5.8 +/- 2.1 yr, respectively. The height velocity in the year prior to treatment, and 0-12 and 12-24 months after commencing treatment was 4.8 +/- 1.0 cm/yr, 7.0 +/- 1.2 cm/yr, and 5.5 +/- 0.6 cm/yr, respectively. The height velocity in the first year of treatment was significantly greater (P = 0.0001, n = 14) than the pretreatment value, but there was no significant difference in the second year. The height SD scores at the commencement of treatment, and after 12 and 24 months of treatment were -2.8 +/- 0.7, -2.4 +/- 0.7, and -2.2 +/- 0.5, respectively. Bone age advanced by 1.1 +/- 0.5 yr in the 12 months after commencing treatment. We conclude that the use of hGH may be beneficial in the treatment of Noonan syndrome, although further research is required.

Age Determination by Skeleton↗

PubMed2004

Association of heavy metals with metallothionein and other proteins in hepatic cytosol of marine mammals and seabirds.

Distribution of Cu, Zn, Cd, Ag, Hg, and Se were determined in hepatocytosol of northern fur seals (Callorhinus ursinus), black-footed albatrosses (Diomedea nigripes), and Dall's porpoises (Phocoenoides dalli). Copper, Zn, and Cd were accumulated preferentially in metallothionein (MT) fraction and their contents in MT fraction increased with the amounts in the hepatocytosol. Silver was bound to both high-molecular-weight substances (HMWS) and MT in the hepatocytosol for all three species, whereas the distribution of Ag in the cytosol was different among the three species. In northern fur seals, Ag mainly was bound to MT, whereas it mainly was associated with HMWS in Dall's porpoises. In contrast, Ag was distributed almost equally in both HMWS and MT for black-footed albatrosses. Mercury content in HMWS and Se content in HMWS and low-molecular-weight substances (LMWS) increased with their contents in hepatocytosol for all the three species. A significant positive correlation was found between Se and Hg contents in high-molecular weight (HMW) fraction in cytosol. The molar ratio of Hg and Se was close to unity in HMW fraction of the specimens with high Hg concentration in cytosol, implying that the Hg-Se complex was bound to the HMWS. Analysis of metals in the hepatocytosol by high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) suggests that multiple isoforms of MT are present in hepatocytosol of the three species and that the metal profiles in hepatocytosols are different among the species. To our knowledge, this is the first report on the association of Ag with HMWS and MT in hepatocytosol of marine mammals and seabirds. Also, distribution and interaction of Hg and Se were investigated for the first time in hepatocytosol of the higher trophic marine animals.

Animals↗

PubMed2004

Acrosome reaction in spermatozoa from the amphioxus Branchiostoma belcheri (Cephalochordata, Chordata).

The formation of an acrosomal process at acrosomal exocytosis in spermatozoa of the amphioxus was described in the present report for the first time. A non-reacted acrosome was located in front of the nucleus, where a cup-shaped acrosomal vesicle covered a conical accumulation of subacrosomal material. When naturally spawned spermatozoa were treated with a calcium ionophore, ionomycin, the acrosomal vesicle opened at the apex and an acrosomal process was projected. The process exhibited a filamentous structure. The reaction followed the mode typically seen in marine invertebrates. These observations suggest that the features and function of the acrosome of amphioxus, whose position is on the border between invertebrates and vertebrates, reflect their ecological adaptation and phylogenic position.

Acrosome Reaction↗

PubMed2004

Sensitive detection of glycyrrhizin and evaluation of the affinity constants by a surface plasmon resonance-based immunosensor.

A sensitive and selective determination of glycyrrhizin (GC) based on surface plasmon resonance (SPR) was performed by using an anti-GC monoclonal antibody (GC-MAb) and GC-bovine serum albumin (GC-BSA) conjugate (antigen). GC-BSA was immobilized on an Au thin film of the SPR sensor chip by physical adsorption, and GC determinations were performed by an indirect competitive method. The addition of GC into the GC-MAb solution (5 microg/ml) was found to decrease the incident-angle shift sharply because of an inhibition effect of GC. The RSDs (n = 3) of each point were less than 4%. The lowest detection limit for GC by SPR was almost the same as that by ELISA, 60-75 ng/ml. An evaluation of the affinity constant between GC-MAb and GC using the data from ELISA and those from SPR measurements was performed. The values of the association constant (KA) from three different analyses of ELISA data and from SPR measurements are discussed in detail. As a whole, the affinity constant (KA) between GC-MAb and GC was on the order of 10(7) M(-1).

Adsorption↗

PubMed2004

Coronary artery bypass in patients 80 years and older: comparison with a younger age group.

Octogenarians are at increased risk for perioperative morbidity and mortality following coronary artery bypass grafting (CABG). We compared the perioperative outcome after CABG from March 1997 to June 2003, between patients 80 years and older (n=15), and those aged 70 to 79 years (n=64). In comparison with younger patients, more octogenarians had congestive heart failure (40% vs. 9% in patients aged 70 to 79 years, p=0.003) and underwent off-pump CABG more frequently (80% vs. 42%, p=0.008). There were no significant differences in the incidence of emergent surgery (27% vs. 28%) and number of bypass grafts (2.3+/-0.7 vs. 2.5+/-0.9) between the two groups. Octogenarians had less complete revascularization compared to the younger group (67% vs. 81%, not significant). There was no mediastinitis, and no stroke in either groups. Octogenarians had more minor wound complications (20% vs. 3%, p=0.01). There were no operative deaths in octogenarians, while the mortality rate of the younger group was high (6%). Surgical myocardial revascularization in octogenarians can be performed with acceptable mortality and morbidity using off-pump CABG.

Age Factors↗

PubMed2004

[Low oxygen saturation during early postoperative period in adult patients receiving opioids by intravenous patient-controlled analgesia].

BACKGROUND: Patient-controlled analgesia (PCA) provides effective postoperative analgesia. However, there are few reports concerning the adverse outcome of respiratory depression. METHODS: We measured arterial oxygen saturation (SpO2) continuously during early postoperative period in 38 adult patients receiving opioids by intravenous PCA. We assessed the severity and incidence of desaturation, defined as SpO2 below 90% for more than 10 seconds. RESULTS: Nine patients showed desaturation and were studied after the surgery of the extremities, body surfaces, thorax or abdomen. Two patients showed desaturation with combination of surgery of long duration and obesity. Six patients, all of whom with liver cirrhosis, underwent thoracic and abdominal procedures, and showed desaturation because of respiratory dysfunction and hypoxemia caused by the surgery itself. One patient showed respiratory depression due to the opioids. CONCLUSIONS: We conclude that careful monitoring with a pulse oximeter and giving oxygen are essential to prevent desaturation during early postoperative period.

Adult↗