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Makoto Tanaka

Publications and source records attributed to Makoto Tanaka.

At least 19 recordsLinked to original sources

A high glycolytic flux supports the proliferative potential of murine embryonic stem cells.

Embryonic stem (ES) cells are immortal and present the ability to self-renew while retaining their ability to differentiate. In contrast, most primary cells possess a limited proliferative potential, and when this is exhausted, undergo an irreversible growth arrest termed senescence. In primary cells, senescence can be also triggered by a variety of stress to which ES cells are highly refractory. Here the authors report that the proliferative capacity of murine ES cells closely correlates with high activity of different glycolytic enzymes, elevated glycolytic flux, and low mitochondrial oxygen consumption. The direct relation between glycolytic flux and the ability of ES cells to proliferate is further remarked in experiments where glycolysis or ES cell self-renewal was specifically inhibited. It was previously reported that the upregulation of glycolysis in primary cells results in life span extension. The authors hypothesize that the naturally high glycolytic flux observed in murine ES cells can be responsible for their unlimited proliferative potential.

Animals↗

Essential role of Hand2 in interventricular septum formation and trabeculation during cardiac development.

Interventricular septum (IVS) formation is one of the key events in the development of a four-chambered heart. We previously showed that the basic helix-loop-helix transcription factor Hand1 plays an important role in the formation of the IVS. Here, we found that the other Hand gene, Hand2, regulated expansion, trabeculation, and IVS formation in the embryonic heart. In transgenic embryos expressing Hand2 in the whole ventricles, the boundary region between the left and right ventricles expanded outwards, resulting in complete absence of the IVS. Moreover, trabecular formation was observed even in a region where the IVS was expected to form. In some transgenic embryos with heterogeneous expression of the transgene, a muscular septum did not form in a region where Hand2 was expressed, but an incomplete septum was identifiable in a region where Hand2 was not expressed, suggesting that septum formation was strictly regulated by the expression domain of Hand2. Furthermore, expression of trabecular markers including ANF, BNP, and connexin40 was significantly up-regulated in the ventricles of Hand2 transgenic embryos as well as in H9c2 cells over-expressing Hand2. These results suggested that the absence of Hand2 expression in the interventricular boundary region inhibits expansion and trabeculation in this area, contributing to the proper formation of the IVS.

Animals↗

Effect of propofol on ropivacaine metabolism in human liver microsomes.

A combination of the general anesthetic propofol and epidural anesthesia with a local anesthetic is widely used. The metabolism of ropivacaine and that of lidocaine are mediated by similar P450 isoforms. Previously, propofol was found to inhibit the metabolism of lidocaine in vitro. Here we investigated whether propofol inhibits the metabolism of ropivacaine using human liver microsomes in vitro. Ropivacaine (6.0 micromol.l(-1)) as the substrate and propofol (1-100 micromol.l(-1)) were reacted together using human microsomes. The concentrations of ropivacaine and its major metabolite 2',6'-pipecoloxylidide (PPX) were measured using high-performance liquid chromatography. The metabolic activity of ropivacaine was reflected in the production of PPX. The inhibitory effects of propofol on ropivacaine metabolism were observed to be dose-dependent. The IC50 of propofol was 34.9 micromol.l(-1). Propofol shows a competitive inhibitory effect on the metabolism of ropivacaine (i.e., PPX production mediated by CYP3A4) in human CYP systems in vitro.

Amides↗

Effect of vasoconstrictor coupling factor 6 on gene expression profile in human vascular endothelial cells: enhanced release of asymmetric dimethylarginine.

BACKGROUND: Coupling factor 6 (CF6), a component of ATP synthase, inhibits phospholipase A2 and induces vasoconstriction. However, because arachidonic acid acts in the widespread fields of vascular biology, CF6 might exert profound effects in addition to vasoconstriction. We investigated the effect of CF6 on the gene expression profile in human umbilical vein endothelial cells. METHODS AND RESULTS: The increased gene expression after 24-h exposure to CF6 at 10 mol/l, assessed by cDNA microarray (n = 3), included neuregulin-1 (1.84 +/- 0.07 fold compared with control, P < 0.05) and relaxin-1 (1.74 +/- 0.20, P < 0.05), both relating to congestive heart failure, urokinase type plasminogen activator receptor (1.77 +/- 0.24, P = 0.06) and estrogen receptor beta (1.74 +/- 0.36, P = 0.08), both relating to vascular inflammation and cell infiltration, and protein arginine methyltransferase (PRMT-1; 1.73 +/- 0.20, P < 0.05). Out of these genes, the enzyme relating to the synthesis (PRMT-1) of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), was further examined concomitantly with the degradation enzyme, dimethylarginine dimethylaminohydrolase 2 (DDAH-2). The ratio of PRMT-1 to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA, measured by real-time quantitative reverse transcription-polymerase chain reaction, was increased by 9 +/- 2% (n = 10, P < 0.01) at 48 h after CF6 at 10 mol/l, whereas the ratio of DDAH-2 to GAPDH was decreased by 12 +/- 2% (n = 8, P < 0.01). DDAH-2 protein and activity were decreased by 28 +/- 5% (n = 5, P < 0.01) and 19 +/- 2% (n = 6, P < 0.01) by CF6, respectively. ADMA release was enhanced by 20 +/- 8% and NOS activity was decreased by 13 +/- 1% (both n = 8, P < 0.05) by CF6. CONCLUSIONS: CF6 changes the gene expression profile to be proatherogenic and functions as a novel stimulator for ADMA release by enhancing its synthesis and suppressing its degradation.

Amidohydrolases↗

Effects of sevoflurane anesthesia on carotid-cardiac baroreflex responses in humans.

Sevoflurane depresses cardio-vagal baroreflex gain (ability of vagally mediated R-R interval response to arterial blood pressure change). We examined the effects of sevoflurane anesthesia on maximum buffering capacity of vagally mediated hemodynamic control (baroreflex range) by examining the entire stimulus-response baroreflex relation. Electrocardiogram and invasive arterial blood pressure were monitored in 11 healthy volunteers. Carotid-cardiac baroreflex responses were elicited by increasing neck chamber pressure (external pressure applied over the bilateral carotid sinuses) to 40 mm Hg for 5 heartbeats followed by decreasing chamber pressure by successive 15-mm Hg R-wave triggered decrements to -65 mm Hg during held expiration. R-R intervals were plotted as functions of preceding carotid distending pressure. Range, maximum gain, and operational point (relative position of the resting set point within the entire baroreflex response curve) were determined at conscious baseline, during 2% (end-tidal) sevoflurane anesthesia, without and with phenylephrine infusion to maintain conscious arterial blood pressure, and at 30, 60, 120, and 180 min after emergence from anesthesia. Sevoflurane anesthesia significantly depressed maximum gain (from 3.84 +/- 0.99 to 1.04 +/- 0.40 ms/mm Hg [mean +/- sd]; P < 0.001) and range (from 207 +/- 43 to 52 +/- 19 ms; P < 0.001) of the reflex relation, both of which recovered at 120 and 180 min after emergence. Phenylephrine infusion only partially restored these variables. The operational point was unchanged throughout the study. Our results indicate that maximum cardio-vagal compensatory response to buffer hemodynamic perturbation is depressed during sevoflurane anesthesia. Sevoflurane-induced hypotension, which produced vagal withdrawal, did not play an important role in depressing cardio-vagal reflex function.

Adult↗

[Collaboration between university hospitals and local medical communities in Japan evaluated by a questionnaire among doctors].

AIM AND METHODS: To provide quality medical service in a society with many elderly, university hospitals should clearly define their roles and contribute to the establishment of an integrated, comprehensive medical system. In this study, we conducted a questionnaire survey of doctors working at Kyoto University Hospital and at private practices in Kyoto about their attitude toward collaboration between the university hospital and private practices and asked their opinions on the role of university hospitals in the local medical community. RESULTS: The survey showed that doctors both at the university hospital and in private practice regarded close collaboration as important, but also highlighted obstacles and problems that block collaboration. CONCLUSION: Overcoming these problems and constructing collaboration models will be a key for university hospitals to fully contribute to the establishment of a quality medical system.

Attitude of Health Personnel↗

Endothelin-1 activates Homer 1alpha expression via mitogen-activated protein kinase in cardiac myocytes.

Homer proteins are a family of scaffolding proteins which may play an important role in calcium signaling by facilitating the assembly of signaling complexes in neuronal cells. Among the three splice variants of Homer 1, Homer 1alpha is rapidly up-regulated by neural stimulation and may regulate the disassembly of signaling complexes mediated by Homer proteins. In spite of its potential importance in calcium signaling, the regulation of Homer 1alpha expression in cardiac myocytes has never been investigated. In this study, we examined the regulation of Homer 1alpha expression in cardiac myocytes. Homer 1alpha was significantly up-regulated by several hypertrophic agonists, including endothelin-1 (ET-1), phenylephrine, isoprotenerol and angiotensin-II, and ET-1 most strikingly induced Homer 1alpha expression. The induction of Homer 1alpha expression by ET-1 peaked at 2 h and inhibitors for mitogen-activated/extracellular signal regulated kinase (MEK) significantly suppressed the induction of Homer 1alpha. This study first clarified the regulation of Homer 1alpha expression in cardiac myocytes and demonstrated that ET-1 induced Homer 1alpha expression through the mitogen-activated protein kinase pathway.

Angiotensin II↗

Redirecting differentiation of hematopoietic progenitors by a transcription factor, GATA-2.

GATA-2 is a zinc finger transcription factor essential for differentiation of immature hematopoietic cells. We analyzed the function of GATA-2 by a combined method of tetracycline-dependent conditional gene expression and in vitro hematopoietic differentiation from mouse embryonic stem (ES) cells using OP9 stroma cells (OP9 system). In the presence of macrophage colony-stimulating factor (M-CSF), the OP9 system induced macrophage differentiation. GATA-2 expression in this system inhibited macrophage differentiation and redirected the fate of hematopoietic differentiation to other hematopoietic lineages. GATA-2 expression commencing at day 5 or day 6 induced megakaryocytic or erythroid differentiation, respectively. Expression levels of PU.1, a hematopoietic transcription factor that interferes with GATA-2, appeared to play a critical role in differentiation to megakaryocytic or erythroid lineages. Transcription of PU.1 was affected by histone acetylation induced by binding of GATA-2 to the PU.1 promoter region. This study demonstrates that the function of GATA-2 is modified in a context-dependent manner by expression of PU.1, which in turn is regulated by GATA-2.

Animals↗

Intracellular signaling for vasoconstrictor coupling factor 6: novel function of beta-subunit of ATP synthase as receptor.

Coupling factor 6 (CF6), a component of adenosine triphosphate (ATP) synthase, is circulating and functions as an endogenous vasoconstrictor by inhibiting cytosolic phospholipase A2. We showed a high plasma level of CF6 in human hypertension. The present study focused on the identification and characterization of a receptor for CF6 and its post-receptor signaling pathway. Incubation of human umbilical vein endothelial cells (HUVECs) with an excess of free CF6 reduced by 50% the immunoreactivity for the antibody to beta-subunit of ATP synthase at the cell surface, but unaffected that for the alpha-subunit antibody. A significant displacement of radioligand was observed at 3x10(-9) through 10(-7) M unlabeled CF6, and the Kd was 7.6 nM. Adenosine diphosphate (ADP) at 10(-7) M and beta-subunit antibody suppressed the binding of (125)I-CF6 by 81.3+/-9.7% and 32.0+/-2.0%, respectively, whereas the alpha-subunit antibody unaffected it. The hydrolysis activity of ATP to ADP was increased by 1.6-fold by CF6 at 10(-7) M, and efrapeptin at 10(-5) M, an inhibitor of ATP synthase, blocked it. CF6 at 10(-7) M decreased intracellular pH in 2',7'-bis(carboxyethyl-5 (6))-carboxyfluorescein-loaded HUVEC. Amyloride at 10(-4) M augmented the pH decrease in response to CF6, whereas efrapeptin at 10(-5) M blocked it. Arachidonic acid release was suppressed by CF6, and it was reversed by efrapeptin at 10(-5) M or beta-subunit antibody or ADP at 10(-7) M. The beta-subunit antibody suppressed coupling factor 6-induced increase in blood pressure. These indicate that membrane-bound ATP synthase functions as a receptor for CF6 and may have a previously unsuspected role in the genesis of hypertension by modulating the concentration of intracellular hydrogen.

Arachidonic Acid↗

Prostaglandin D2 and prostaglandin E2 accelerate the recovery of cutaneous barrier disruption induced by mechanical scratching in mice.

The role of prostaglandins in mechanical scratching-induced cutaneous barrier disruption in mice was investigated. Skin prostaglandins contents were measured after cutaneous barrier function was disrupted by scratching using a stainless-steal wire brush (mechanical scratching), then effects of prostanoids on recovery of cutaneous barrier functions were examined. This mechanical scratching increased transepidermal water loss and skin prostaglandins (prostaglandin D2, prostaglandin E2, 6-keto-prostaglandin F1alpha and prostaglandin F2alpha) contents, count-dependently. Topical application of indomethacin immediately after cutaneous barrier disruption delayed the recovery period of cutaneous barrier disruption. We examined effects of several prostanoids (prostaglandin D2, prostaglandin E2, prostaglandin F2alpha, prostaglandin I2 and U46619) on delay of the recovery process of mechanical scratching-induced cutaneous barrier disruption with treatment of indomethacin. Topically applied prostaglandin D2 and prostaglandin E2 accelerated the recovery of cutaneous barrier disruption and topical application of prostaglandin J2, limaprost, sulprostone and ONO-4819, but not 13,14-dihydro-15-keto-prostaglandin D2, 15-deoxy-Delta(12,14)-prostaglandin J2, 17-phenyl-trinor-prostaglandin E2 or butaprost had effects on recovery of the cutaneous barrier. These results suggest that prostaglandin D2 and prostaglandin E2 accelerate the recovery process of cutaneous barrier disruption caused by mechanical scratching, via specific prostanoid DP1, EP3 and EP4 receptors.

6-Ketoprostaglandin F1 alpha↗

CXCL16 is a novel angiogenic factor for human umbilical vein endothelial cells.

CXCL16 is a unique chemokine with characteristics as a receptor for phosphatidylserine and oxidized low density lipoproteins in macrophages, and is involved in the accumulation of cellular cholesterol during atherosclerotic lesion development. In this study, we report a new function of CXCL16 as a novel angiogenic factor in human umbilical vein endothelial cells (HUVEC). CXCL16 stimulated proliferation and chemotaxis of HUVEC in a dose-dependent manner, reaching a maximum at 1 nM. CXCL16 also significantly induced tube formation of HUVEC on Matrigel. Further, exposure of HUVEC to CXCL16 led to a time- and dose-dependent activation of mitogen-activated protein kinase (ERK1/2), which was completely inhibited by a mitogen-activated protein kinase kinase inhibitor, PD98059. Proliferation and tube formation in response to CXCL16 were also blocked by the pretreatment with PD98059, but not CXCL16-induced chemotaxis. Thus, our data indicate that CXCL16 may act as a novel angiogenic factor for HUVEC and that ERK is involved as an important signaling molecule to mediate its angiogenic effects.

Cell Movement↗

Expression of IL-31 gene transcripts in NC/Nga mice with atopic dermatitis.

To search for the pruritogen of atopic dermatitis, a characteristic symptom in atopic dermatitis patients, we examined interleukin-31 (IL-31) mRNA expression in NC/Nga mice as an animal model of atopic dermatitis. The expression of IL-31 mRNA in the skin of NC/Nga mice with scratching behavior was significantly higher than that in NC/Nga mice without scratching behavior. Our findings suggest that IL-31 may participate in the cause of itch sensation and promote scratching behavior in NC/Nga mice with atopic dermatitis.

Animals↗

Prostaglandin D2 inhibits IgE-mediated scratching by suppressing histamine release from mast cells.

Effects of prostaglandin (PG) D(2), PGE(2), and PGI(2) on itch-associated scratching responses of mice and histamine release from the rat basophilic leukemia cell line RBL-2H3 were examined. PGD(2) and ketotifen but not PGE(2) and PGI(2) suppressed the scratching caused by ovalbumin injected into ovalbumin-sensitized mice. Ketotifen also suppressed compound 48/80-induced scratching but not PGD(2), PGE(2), and PGI(2). In vitro, PGD(2) suppressed the antigen-induced histamine release from RBL-2H3 cells, but PGE(2) and PGI(2) did not. These findings suggest that PGD(2) specifically suppressed IgE-mediated scratching by inhibiting IgE-mediated histamine release from mast cells.

Animals↗

Acyl glucuronidation of fluoroquinolone antibiotics by the UDP-glucuronosyltransferase 1A subfamily in human liver microsomes.

Acyl glucuronidation is an important metabolic pathway for fluoroquinolone antibiotics. However, it is unclear which human UDP-glucuronosyltransferase (UGT) enzymes are involved in the glucuronidation of the fluoroquinolones. The in vitro formation of levofloxacin (LVFX), grepafloxacin (GPFX), moxifloxacin (MFLX), and sitafloxacin (STFX) glucuronides was investigated in human liver microsomes and cDNA-expressed recombinant human UGT enzymes. The apparent Km values for human liver microsomes ranged from 1.9 to 10.0 mM, and the intrinsic clearance values (calculated as Vmax/Km) had a rank order of MFLX > GPFX > STFX > > LVFX. In a bank of human liver microsomes (n = 14), the glucuronidation activities of LVFX, MFLX, and STFX correlated highly with UGT1A1-selective beta-estradiol 3-glucuronidation activity, whereas the glucuronidation activity of GPFX correlated highly with UGT1A9-selective propofol glucuronidation activity. Among 12 recombinant UGT enzymes, UGT1A1, 1A3, 1A7, and 1A9 catalyzed the glucuronidation of these fluoroquinolones. Results of enzyme kinetics studies using the recombinant UGT enzymes indicated that UGT1A1 most efficiently glucuronidates MFLX, and UGT1A9 most efficiently glucuronidates GPFX. In addition, the glucuronidation activities of MFLX and STFX in human liver microsomes were potently inhibited by bilirubin with IC50 values of 4.9 microM and 4.7 microM, respectively; in contrast, the glucuronidation activity of GPFX was inhibited by mefenamic acid with an IC50 value of 9.8 microM. These results demonstrate that UGT1A1, 1A3, and 1A9 enzymes are involved in the glucuronidation of LVFX, GPFX, MFLX, and STFX in human liver microsomes, and that MFLX and STFX are predominantly glucuronidated by UGT1A1, whereas GPFX is mainly glucuronidated by UGT1A9.

Animals↗

An increase of oxidized coenzyme Q-10 occurs in the plasma of sporadic ALS patients.

We have compared plasma redox status of coenzyme Q-10 in 20 sporadic amyotrophic lateral sclerosis (sALS) patients with those in 20 healthy age/sex-matched controls. A significant increase in the oxidized form of coenzyme Q-10 (sALS=109.3+/-95.2 nM; controls=23.3+/-7.5 nM, P=0.0002) and in the ratio of oxidized form of coenzyme Q-10 to total coenzyme Q-10 (%CoQ-10) (sALS=12.0+/-9.3%; controls=3.2+/-0.9%, P<0.0001) were observed. Moreover, %CoQ-10 correlated significantly with the duration of illness (rho=0.494, P=0.0315). Our finding suggests systemic oxidative stress in the pathogenesis of sALS.

Adult↗

Appraisal of surgical treatment for pulmonary metastasis from hepatocellular carcinoma.

The outcome of pulmonary metastasectomy of hepatocellular carcinoma (HCC) was appraised in this study. Twenty patients with pulmonary metastasis from HCCs undergoing pulmonary resection between 1990 and 2003 were included in this study. They had undergone curative treatment for the primary lesion and were candidates for a pulmonary metastasectomy for complete resection. Among the 20 patients, 13 died: 5 from hepatic failure, 5 from respiratory failure, and 2 from brain metastasis due to recurrence of the HCC. One patient died from cardiac failure without HCC recurrence. At the latest observation, three of the seven survivors were doing well without HCC recurrence, and others survived with recurrence. The overall survival rates after the initial lung surgery were 45.3% at 1 year and 23.8% at 3 years, respectively. The survival rates without recurrence were 32.4% at 1 year and 21.6% at 3 years, respectively. A Kaplan-Meier analysis showed that multiple lung surgeries and a negative histologic finding of the liver cut surface were favorable characteristics for survival without recurrence. In conclusion, the selected patients were Candidates for pulmonary metastasectomy after a curative hepatectomy for HCC and could benefit from the complete resection. Also, repeated pulmonary resections through thoracoscopy could result in the long-term survival of patients with pulmonary recurrence of HCC.

Adult↗

Landiolol attenuates the cardiovascular response to tracheal intubation.

PURPOSE: The objective of this prospective study was to compare the cardiovascular responses with or without landiolol to the induction of general anesthesia and tracheal intubation. METHODS: Twenty-two patients were randomly allocated to receive a loading dose of landiolol 125 microg kg(-1) min(-1) for 1 min followed by an infusion at 40 microg kg(-1) min(-1) for 4 min, or placebo. Four minutes after landiolol or placebo was started, propofol and succinylcholine were administered. Laryngoscopy and tracheal intubation were performed 1 min after the administration of succinylcholine. Heart rate and blood pressure were measured noninvasively every minute. RESULTS: A significant attenuation of the heart rate and blood pressure response were seen in the landiolol group for 3 min after intubation. Heart rate and systolic blood pressure in the landiolol group were decreased for 2 min before intubation and just before intubation compared with baseline, respectively. CONCLUSION: Continuous administration of landiolol before tracheal intubation results in the attenuation of cardiovascular response for tracheal intubation.

Adrenergic beta-Antagonists↗

Coccidioidomycosis of the lung contracted abroad.

Coccidioides immitis is endemic in the southwestern United States. Coccidioidomycosis is rare in Japan, but the number of coccidioidomycosis cases from overseas is expected to increase markedly in the near future. A 33-year-old Japanese man with coccidioidomycosis who had lived in Arizona presented to our hospital. We performed wedge resection of the lung by video-assisted thoracoscopic surgery (VATS), and were able to completely remove the lesion. VATS wedge resection of the lung is effective in treating localized coccidioidomycosis. Before the operation, we could not confirm the existence of satellite lesions, but microscopically the main lesion was accompanied by several daughter lesions. It is very important that the surgical margin be sufficient to achieve complete resection.

Adult↗