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Biomedical subjects

H Tsutsui

Publications and source records attributed to H Tsutsui.

At least 91 records · Page 5Linked to original sources
PubMed1998

Regulation of interferon-gamma production by IL-12 and IL-18.

IL-18 (interferon-inducing factor) and IL-12 exhibit a marked synergism in interferon-gamma induction in T cells. Investigations into the mechanism of this synergism have revealed that IL-12 upregulates expression of the IL-18 receptor on cells producing interferon-gamma. Although IL-18 does not induce the development of Th1 cells, it is essential for the effective induction and activation of Th1 cells by IL-12. As for natural killer cells, IL-18 seems to activate them independently of IL-12. Although IL-12 and IL-18 activate both innate and acquired immunity, their excessive production by activated macrophages may induce multiple organ disorders including disruption of the immune system.

Animals↗
PubMed1998

Defective NK cell activity and Th1 response in IL-18-deficient mice.

IL-18 is a cytokine that is secreted from activated macrophages and induces IFNgamma production. To investigate the in vivo role of IL-18, we generated IL-18-deficient mice. In Propionibacterium acnes (P. acnes)-primed IL-18-deficient mice, LPS-induced IFNgamma production was markedly reduced, despite normal IL-12 induction. Natural killer cell activity was significantly impaired. Th1 cell response after injection of P. acnes or Mycobacterium bovis (bacillus Calmette-Guerin [BCG]) was significantly reduced. Similar results were observed in IL-12-deficient mice. Interestingly, Th1 response was induced after BCG infection in IL-12-deficient mice. We therefore generated mice lacking both IL-18 and IL-12. In these mice, NK activity and Th1 response were further impaired. This demonstrates the important role of both IL-18 and IL-12 in NK activity, as well as in in vivo Th1 response.

Animals↗
PubMed1998

Targeted disruption of the MyD88 gene results in loss of IL-1- and IL-18-mediated function.

MyD88, originally isolated as a myeloid differentiation primary response gene, is shown to act as an adaptor in interleukin-1 (IL-1) signaling by interacting with both the IL-1 receptor complex and IL-1 receptor-associated kinase (IRAK). Mice generated by gene targeting to lack MyD88 have defects in T cell proliferation as well as induction of acute phase proteins and cytokines in response to IL-1. Increases in interferon-gamma production and natural killer cell activity in response to IL-18 are abrogated. In vivo Th1 response is also impaired. Furthermore, IL-18-induced activation of NF-kappaB and c-Jun N-terminal kinase (JNK) is blocked in MyD88-/- Th1-developing cells. Taken together, these results demonstrate that MyD88 is a critical component in the signaling cascade that is mediated by IL-1 receptor as well as IL-18 receptor.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Role of SR Ca2+-ATPase in contractile dysfunction of myocytes in tachycardia-induced heart failure.

Sarcoplasmic reticulum (SR) Ca2+-ATPase gene expression is reduced in the failing myocardium. However, the functional relevance of these changes to myocardial contractility is not yet established. We assessed myocardial contractile function by analyzing sarcomere motion of isolated myocytes and also quantified SR Ca2+ regulatory protein gene expression by Northern blot analysis in the same hearts obtained from 10 dogs with pacing-induced heart failure (HF; 240 beats/min, 4 wk) and 7 control dogs. Sarcomere-shortening velocity was depressed in HF myocytes, accompanied by the prolongation of intracellular Ca2+ concentration ([Ca2+]i) transient measured by indo 1 fluorescence ratio. SR Ca2+-ATPase mRNA levels (normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA) were significantly depressed in HF, and calsequestrin mRNA was increased. For control and HF dogs, sarcomere-shortening velocity correlated positively with Ca2+-ATPase mRNA levels (r = 0.73, n = 17, P < 0.01) but not with calsequestrin mRNA. Ca2+-ATPase mRNA levels were correlated with 45Ca2+ uptake rate by SR, which was also reduced in HF. Moreover, the inhibition of SR Ca2+-ATPase with thapsigargin or cyclopiazonic acid reproduced in normal myocytes the abnormalities observed in HF myocytes, such as depressed contractility and the prolonged [Ca2+]i transient duration. A downregulation of Ca2+-ATPase gene expression and a resultant decrease in Ca2+ uptake by SR may be responsible for the contractile dysfunction and the alterations of [Ca2+]i transient in HF.

Animals↗
PubMed1998

Microtubules are involved in early hypertrophic responses of myocardium during pressure overload.

Mechanical overloading to cardiac muscle causes fetal contractile protein gene expression and acceleration of protein synthesis. Myocyte microtubules might be involved in these pressure overload-induced hypertrophic responses. We assessed c-fos and fetal contractile protein genes such as beta-myosin heavy chain (MHC) and alpha-skeletal actin using Northern blot analysis and quantified total cardiac protein, DNA, and RNA content in the left ventricular myocardium obtained from four groups of rats: sham-operated rats; sham-operated rats treated with colchicine, which depolymerized microtubules; rats in which acute pressure overload was imposed by abdominal aortic constriction for 3 days (AoC); and AoC rats treated with colchicine (AoC + colchicine). Systolic arterial pressure was elevated to a similar degree in AoC and AoC + colchicine rats. c-fos and beta-MHC mRNA levels were significantly upregulated in AoC rats, which was attenuated by microtubule inhibition. Both RNA content and RNA-to-DNA ratio, the index of the protein synthesis capacity, were increased in AoC rats, which effect was also abolished by colchicine. Furthermore, induction of nonfunctioning microtubules by taxol or deuterium oxide exerted the same inhibitory effects. Thus the hypertrophic responses of the myocardium during pressure overload might depend on the integrity of myocyte microtubules.

Actins↗
PubMed1998

Synthesis and quantitative structure-activity relationships of N-(3-oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbonyl)guanidines as Na/H exchange inhibitors.

N-(3-Oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbonyl)guanidines 4 were prepared and tested for Na/H exchange inhibitory activities in order to clarify the structure-activity relationship (SAR). Quantitative SAR (QSAR) analysis of 6-carbonylguanidines 4 indicated that the length of the 4-substituent was parabolically related to activity and that the calculated optimum 4-substituents were propyl, ethyl and isopropyl groups. This SAR was similar to the SAR of the 2- and 4-substituents of 7-carbonylguanidine derivatives 3, although the position relative to the essential guanidinocarbonyl group was different. Larger 2-substituents, such as a phenyl group were unfavorable. The most potent derivative in this series was N-(4-isopropyl-2,2-dimethyl-3-oxo-3,4-dihydro- 2H-benzo[1,4]oxazine-6-carbonyl)guanidine 4 g, with an IC50 value of 0.12 microM. The methanesulfonate salt (KB-R9032) of 4g had excellent water-solubility and showed anti-arrhythmia activity against a rat acute myocardial infarction model. KB-R9032 was selected for further investigation as a therapy for ischemia-reperfusion induced injury.

Animals↗
PubMed1997

Negative inotropic effect of basic fibroblast growth factor on adult rat cardiac myocyte.

BACKGROUND: Basic fibroblast growth factor (bFGF) is highly expressed in the myocardium in some cardiac disorders, such as ischemia-reperfusion and cardiac allograft rejection. However, whether bFGF has any effects on myocardial contraction is unknown. METHODS AND RESULTS: We examined the effects of bFGF on myocardial contractility using isolated adult rat cardiac myocyte preparations. bFGF exerted a direct negative inotropic effect that was concentration and time dependent. The pretreatment of myocytes with a neutralizing anti-bFGF antibody (100 ng/mL) abolished the negative inotropic effects of bFGF (100 ng/mL). Platelet-derived growth factor (12.5 ng/mL) and transforming growth factor-beta (1 ng/mL) did not exert such effects, which indicated that bFGF-induced negative inotropism was considered to be specific for this growth factor. bFGF decreased the peak intracellular Ca2+ transient by 46% during systole. The enhanced production of nitric oxide was unlikely to be responsible for the bFGF-induced negative inotropic effect. CONCLUSIONS: bFGF, primarily a potent growth promoter, produced acute negative inotropic effects in the adult cardiac myocyte that could have resulted from alterations in intracellular Ca2+ homeostasis. The negative inotropic effect of bFGF may contribute to myocardial dysfunction associated with ischemia-reperfusion injury and heart transplant rejection.

Animals↗
PubMed1997

IL-18 accounts for both TNF-alpha- and Fas ligand-mediated hepatotoxic pathways in endotoxin-induced liver injury in mice.

When LPS is administered to heat-killed Propionibacterium acnes-primed BALB/c nude mice, they develop endotoxin-induced liver injury. As previously reported, this liver injury can be prevented by treatment with an Ab against IL-18, a novel cytokine with the ability to induce IFN-gamma production and up-regulate functional Fas ligand (FasL) expression. To identify the pathologic role of IL-18 in this liver injury, we investigated the hepatic cytokine network and FasL induction after LPS challenge. After LPS challenge to BALB/c nude mice, their livers expressed IL-12 mRNA, followed by the induction of IFN-gamma and FasL mRNA and then by the late elevation of TNF-alpha mRNA, but stably expressed IL-18 mRNA. The TNF-alpha induction curve had two peaks. The first peak was the result of the direct reaction to LPS, and the late peak might have been induced, since P. acnes-elicited Kupffer cells showed one-peak TNF-alpha kinetics in response to LPS stimulation in vitro. LPS-activated P. acnes-elicited Kupffer cells secreted both IL-12 and IL-18, as determined by ELISA and bioassay, respectively. The in vivo administration of anti-IL-18 just before an LPS challenge suppressed not only the induction of IFN-gamma and the late TNF-alpha elevation, but also the FasL induction, resulting in the total prevention of liver injury, whereas such an anti-IL-12 treatment did not. Anti-IFN-gamma treatment reduced the late increase in TNF-alpha, but not FasL, resulting in a partial prevention of the liver injury. The administration of anti-TNF-alpha just before elevation of the late TNF-alpha peak also markedly, but incompletely, suppressed the LPS-induced liver injury. These data suggested that IL-18 activates both TNF-alpha- and FasL-mediated hepatocytotoxic pathways in endotoxin-induced liver injury.

Animals↗
PubMed1997

MAZ, a Myc-associated zinc finger protein, is essential for the ME1a1-mediated expression of the c-myc gene during neuroectodermal differentiation of P19 cells.

To investigate whether MAZ (Myc-associated zinc finger protein) affects the expression of the c-myc gene during the retinoic acid-induced (RA-induced) neuroectodermal differentiation of P19 embryonal carcinoma (EC) cells, we introduced a CAT reporter construct, human c-myc promoter/CAT (pMyc2CAT), and a mutant CAT derivative that lacked an ME1a1 site (pMyc1CAT) into P19EC cells to monitor the promoter activity of the c-myc gene. The expression of CAT in pMyc2CAT-transformed cells declined fivefold after 24 h in the presence of RA, returned to the normal level within 48 h, and decreased again to below 20% of the normal level after 96 h. By contrast, the expression of CAT in pMyc1CAT-transformed cells did not return to the normal level after 48 h in the presence of RA. In addition, an electrophoretic mobility shift assay (EMSA) with ME1a1 DNA as probe demonstrated that the kinetics of the DNA-binding activity of MAZ were closely correlated with the changes in the expression of CAT from the c-myc promoter/CAT gene during the differentiation of P19EC cells. Taken together, these results suggest that MAZ plays a key role in the transient increase in the expression of the c-myc gene after 48 h of exposure to RA during the neuroectodermal differentiation of P19EC cells.

Animals↗
PubMed1997

Propionibacterium acnes treatment diminishes CD4+ NK1.1+ T cells but induces type I T cells in the liver by induction of IL-12 and IL-18 production from Kupffer cells.

LPS injection into normal mice does not induce liver injury, while the same treatment of Propionibacterium acnes-primed mice induces severe liver injury, indicating that P. acnes treatment renders the mice susceptible to LPS. Since IFN-gamma sensitizes macrophages to LPS, we investigated the mechanism of induction and activation of IFN-gamma-producing (type 1) T cells by P. acnes. Twenty percent of liver lymphocytes of C57BL/6 mice are CD4+ NK1.1+ T cells that promptly produce IL-4 in response to anti-CD3 in vitro. However, P. acnes treatment diminished these lymphocytes. Therefore, liver lymphocytes from P. acnes-primed mice showed reduced IL-4 production. Furthermore, P. acnes treatment induced CD4- type 1 T cells in the liver. Isolated P. acnes-elicited Kupffer cells produced IL-12 and to a lesser degree IL-18 in vitro. Injection of anti-IL-12 Ab totally abrogated these actions of P. acnes, while injection of anti-IL-18 Ab caused only partial abrogation. Thus, administration of P. acnes diminished CD4+ NK1.1+ T cells, but induced type 1 T cells in the liver by induction of IL-12 and IL-18 production. Injection of IL-12 (approximately 1,000 ng) dose dependently diminished CD4+ NK1.1+ T cells, but induced type 1 T cells. In contrast, injection of IL-18 (approximately 1,000 ng) failed, although injection of a much larger dose of IL-18 (10,000 ng) or IL-18 (approximately 1,000 ng) with suboptimal doses of IL-12 (1-100 ng) diminished CD4+ NK1.1+ T cells in a dose-dependent manner. Thus, P. acnes treatment renders the mice highly susceptible to LPS by induction and activation of type 1 T cells.

Animals↗
PubMed1997

Intravascular ultrasonic evidence for importance of plaque distribution (eccentric vs circumferential) in determining distensibility of the left anterior descending artery.

Although previous studies have shown that coronary atherosclerosis is accompanied by impaired vessel wall compliance, few data exist regarding the regional vessel distensibility that may be important in order to gain an insight into the mechanism of atherosclerotic plaque rupture. Therefore, we analyzed 45 coronary sites of the proximal left anterior descending artery from 40 patients. Using intravascular ultrasound, luminal area in diastole (A) and in systole was measured at the diseased sites. With the ratio of luminal area changes (dA) to coronary pressure changes (dP) during a cardiac cycle, the total distensibility index was obtained by the formula: [(dA/A)/dP] x 10(3). At the sites with noncircumferential disease perimeters in diastole (L) and in systole were measured at the normal and narrowed portions. Using the changes in perimeters (dL) during a cardiac cycle, the regional distensibility index was obtained by the formula: [(dL/L)/dP] x 10(3). In 22 sites with circumferential disease, the total distensibility index was 1.03 +/- 0.61/mm Hg (mean +/- SD), and significantly lower than that from 23 sites with noncircumferential disease that showed 1.45 +/- 0.89/mm Hg (p <0.05). In noncircumferential disease, the regional distensibility index at narrowed portions was significantly lower, 0.33 +/- 0.47/mm Hg, than that at normal portion, 1.11 +/- 0.75/mm Hg (p <0.01), suggesting the heterogenous distribution of regional wall distensibility in noncircumferential lesions. These results indicate that the heterogeneous regional wall distensibility exists at the sites with noncircumferential disease where the total vessel distensibility is preserved by the presence of the compliant normal portion.

Adult↗
PubMed1997

Regulation of fibrillar collagen gene expression and protein accumulation in volume-overloaded cardiac hypertrophy.

BACKGROUND: Interstitial collagen accumulation has been extensively demonstrated to be increased at both mRNA and protein levels in pressure-overloaded cardiac hypertrophy. However, few data are available regarding the effects of volume overload on myocardial collagens. METHODS AND RESULTS: To determine whether the alterations of collagens may occur in volume-overloaded cardiac hypertrophy, we measured collagen types I and III mRNA levels and protein accumulation in left ventricular (LV) myocardium of rats at 3, 7, and 28 days after the creation of an aortocaval (AC) shunt. Eccentric LV hypertrophy was produced in rats with AC shunting. Northern blot analysis on RNA extracted from LV tissue indicated that the steady state mRNA levels for both type I and III collagen were persistently upregulated in AC shunt rats compared with sham-operated operated control rats. In contrast, the biochemical collagen protein concentration and morphometric collagen volume fraction were comparable between sham-operated control and AC shunt rats at any study time point. Furthermore, the immunohistochemical staining of types I and III collagen and Sirius red staining on myocardial tissue sections revealed no significant alterations in the distribution or density of fibrillar collagens in AC shunt rats. Tissue collagenase activity was not different between control and AC shunt rats after 28 days. CONCLUSIONS: Cardiac volume overload increases LV collagen mRNA as does pressure overload. However, in contrast to pressure-overloaded hypertrophy, the upregulation of collagen transcriptional activity does not result in subsequent myocardial fibrosis in volume-overloaded hypertrophy due to AC shunting. Therefore, the upregulation of collagen gene expression and protein accumulation might be different in pressure-overloaded and volume overloaded hypertrophy.

Animals↗
PubMed1997

Role of myocyte nitric oxide in beta-adrenergic hyporesponsiveness in heart failure.

BACKGROUND: The positive inotropic response to beta-adrenergic stimulation is attenuated at the isolated myocyte level in heart failure. Nitric oxide (NO) has a negative inotropic effect and attenuates the response to isoproterenol. It has been suggested that NO synthesis is increased in failing myocytes. However, the pathophysiological consequences after induction of NO in myocyte contractility are less clear in the setting of heart failure. METHODS AND RESULTS: We examined the effects of an NO synthase (NOS) inhibitor on contractile function in myocytes isolated from 11 dogs with rapid pacing-induced heart failure (ejection fraction, 29 +/- 2%) and 8 control dogs (ejection fraction, 74 +/- 3%). Sarcomere shortening velocity was measured as an index of contractility under four experimental conditions: at baseline, after adding isoproterenol (ISO; 1 nmol/L), after an NOS inhibitor (N pi-nitro-L-arginine methyl ester [L-NAME], 0.1 nmol/L), and after L-NAME plus ISO. L-NAME alone had no effects on basal sarcomere shortening velocity in either control or heart failure myocytes. However, L-NAME significantly augmented the inotropic response to isoproterenol in heart failure myocytes (107.1 +/- 7.3% [ISO alone] versus 140.6 +/- 10.7% [ISO plus L-NAME] increase from baseline; P < .05) but not in control myocytes (135.5 +/- 9.9% [ISO alone] versus 137.1 +/- 11.4% [ISO plus L-NAME]; P = NS). Myocardial NOS activity measured by the conversion of arginine to citrulline was significantly increased in dogs with heart failure compared with that in control dogs. CONCLUSIONS: The increased NO induction in failing myocytes does not alter baseline sarcomere mechanics but attenuates the positive inotropic response to isoproterenol. Thus, myocyte NO plays an important role in the autocrine regulation of the contractile function of myocytes in congestive heart failure.

Adrenergic beta-Agonists↗
PubMed1997

Important role of tissue angiotensin-converting enzyme activity in the pathogenesis of coronary vascular and myocardial structural changes induced by long-term blockade of nitric oxide synthesis in rats.

The long-term administration of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthesis, produces coronary vascular remodeling and myocardial hypertrophy in animals. This study used a rat model to investigate the role of angiotensin I converting enzyme (ACE) in the pathogenesis of such changes. We studied the following groups, all of which received drug treatment in their drinking water: untreated controls, and those administered L-NAME, L-NAME, and an ACE inhibitor (ACEI), and L-NAME and hydralazine. Cardiovascular structural changes and tissue ACE activities were evaluated after the first, fourth, and eighth week of treatment. In rats treated with L-NAME alone, vascular remodeling was evident at the fourth and eighth week, and myocardial hypertrophy was present at the eighth week of treatment. The vascular and myocardial remodeling were characterized by increased tissue ACE activities and immunodetectable ACE in those tissues. These changes were markedly reduced by ACEI, but not by hydralazine treatment. Increased local ACE expression may thus be important in the pathogenesis of cardiovascular remodeling in this model.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Activation of interferon-gamma inducing factor mediated by interleukin-1beta converting enzyme.

The interleukin-1beta (IL-1beta) converting enzyme (ICE) processes the inactive IL-1beta precursor to the proinflammatory cytokine. ICE was also shown to cleave the precursor of interferon-gamma inducing factor (IGIF) at the authentic processing site with high efficiency, thereby activating IGIF and facilitating its export. Lipopolysaccharide-activated ICE-deficient (ICE-/-) Kupffer cells synthesized the IGIF precursor but failed to process it into the active form. Interferon-gamma and IGIF were diminished in the sera of ICE-/- mice exposed to Propionibacterium acnes and lipopolysaccharide. The lack of multiple proinflammatory cytokines in ICE-/- mice may account for their protection from septic shock.

Animals↗
PubMed1997

Induction of apoptosis in a human hepatocellular carcinoma cell line by a neutralizing antibody to transforming growth factor-alpha.

A cell line derived from a Japanese man with hepatocellular carcinoma was established in culture and designated OCUH-16. The cell line has the morphological and chromosomal features of hepatocellular carcinoma cells and has a short doubling time (approximately 33 h). OCUH-16 cells were shown to express transforming growth factor-alpha (TGF-alpha) in addition to albumin, DNA polymerase-alpha, c-JUN, and the retinoblastoma gene product. Electron microscopy revealed TGF-alpha immunoreactivity associated with the cell membrane, but TGF-alpha was not detected in medium conditioned by OCUH-16 cells by enzyme-linked immunosorbent assay. Reverse transcription and polymerase chain reaction analysis revealed the presence of TGF-alpha messenger RNA in these cells. Culture of OCUH-16 cells in the presence of a neutralizing antibody to TGF-alpha inhibited cell proliferation and induced many cells to undergo apoptosis (programmed cell death). These observations suggest that endogenous TGF-alpha is necessary for OCUH-16 cell growth.

Antibodies, Monoclonal↗
PubMed1997

Magnetic iron oxide particles coated with carboxydextran for parenteral administration and liver contrasting. Pre-clinical profile of SH U555A.

RATIONALE AND OBJECTIVES: To evaluate the physical and pharmacological profiles of SH U555A, a suspension of magnetic iron oxide particles that is designed to enhance the visualization of liver tumors and metastases. MATERIAL AND METHODS: Chemical and physical methods were used to characterize the size and structure of these magnetic iron oxide particles in aqueous solution. The biodistribution and pharmacokinetics of the particles were studied in mice, rats and dogs. The imaging efficacy of the particles was demonstrated by MR imaging in rat liver tumors RESULTS: The SH U555A particles consist of low-molecular-weight carboxydextran-coated iron oxides predominantly of the gamma-Fe2O3 form with a hydrodynamic diameter ranging from 57-59 nm and strong T2 relaxivity of 164 liters x mmol(-1) x s(-1) (water, 0.47 T). In rats the particles exhibited a dose-dependent half-life of between 2 and 3 days in the liver at a dose of 20 micromol Fe/kg and a shorter half-life at lower doses. No major side effects were found. In a rat tumor model the tumor-to-liver contrast was markedly improved after i.v. administration of SH U555A. At a dose of 14 micromol Fe/kg the half-maximal contrast-effect was obtained even in nonoptimized T1-weighted spin-echo images. CONCLUSION: SH U555A is a superparamagnetic MR contrast agent for i.v. administration and has substantial potential for the demarcation of liver tumors.

Animals↗