Publications by authors named "Toshiyuki Chisaka"

21 Publications

  • Page 1 of 1

Surgical Unroofing for Intramural Aortic Course of Left Main Coronary Artery Leading Reverse Vessel Remodeling.

Circ Cardiovasc Imaging 2020 11 10;13(11):e010740. Epub 2020 Nov 10.

Department of Regional Pediatrics and Perinatology (Y.A., T.C., T.H., M.E.), Ehime University Graduate School of Medicine, Toon, Japan.

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http://dx.doi.org/10.1161/CIRCIMAGING.120.010740DOI Listing
November 2020

Brain Abscess Associated with Polymicrobial Infection after Intraoral Laceration: A Pediatric Case Report.

Case Rep Pediatr 2020 9;2020:8304302. Epub 2020 Mar 9.

Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.

Brain abscesses, infections within the brain parenchyma, can arise as complications of various conditions including infections, trauma, and surgery. However, brain abscesses due to polymicrobial organisms have rarely been reported in children. We herein report a case of a 9-year-old girl with unresolved congenital cyanotic heart disease (CCHD) presenting with right hemiplegia who was diagnosed with brain abscess caused by , , and after oropharyngeal injury. She was treated with intravenous antimicrobial therapy, drainage under craniotomy, and antiedema therapy with glycerol and goreisan, which led to the improvement of right hemiplegia to baseline; she was discharged following eight weeks of intravenous antimicrobial therapy. The clinical diagnosis of the brain abscess was difficult due to the nonspecific presentation, highlighting the importance of cranial imaging without haste in patients at increased risk for brain abscesses such as those with CCHD, presenting with fever in the absence of localizing symptoms or fever, accompanied with abnormal neurological findings.
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http://dx.doi.org/10.1155/2020/8304302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7085370PMC
March 2020

Deficiency of angiotensin-converting enzyme 2 causes deterioration of cognitive function.

NPJ Aging Mech Dis 2016 20;2:16024. Epub 2016 Oct 20.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Ehime, Japan.

The classical renin-angiotensin system (RAS), known as the angiotensin (Ang)-converting enzyme (ACE)/Ang II/Ang II type 1 (AT1) receptor axis, induces various organ damages including cognitive decline. On the other hand, the ACE2/Ang-(1-7)/Mas receptor axis has been highlighted as exerting antagonistic actions against the classical RAS axis in the cardiovascular system. However, the roles of the ACE2/Ang-(1-7)/Mas axis in cognitive function largely remain to be elucidated, and we therefore examined possible roles of ACE2 in cognitive function. Male, 10-week-old C57BL6 (wild type, WT) mice and ACE2 knockout (KO) mice were subjected to the Morris water maze task and Y maze test to evaluate cognitive function. ACE2KO mice exhibited significant impairment of cognitive function, compared with that in WT mice. Superoxide anion production increased in ACE2KO mice, with increased mRNA levels of NADPH oxidase subunit, p22, p40, p67, and gp91 in the hippocampus of ACE2KO mice compared with WT mice. The protein level of SOD3 decreased in ACE2KO mice compared with WT mice. The AT1 receptor mRNA level in the hippocampus was higher in ACE2KO mice compared with WT mice. In contrast, the AT2 receptor mRNA level in the hippocampus did not differ between the two strains. Mas receptor mRNA was highly expressed in the hippocampus compared with the cortex. Brain-derived neurotrophic factor (BDNF) mRNA and protein levels were lower in the hippocampus in ACE2KO mice compared with WT mice. Taken together, ACE2 deficiency resulted in impaired cognitive function, probably at least in part because of enhanced oxidative stress and a decrease in BDNF.
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http://dx.doi.org/10.1038/npjamd.2016.24DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5515001PMC
October 2016

Installation of multiple automated external defibrillators to prevent sudden death in school-aged children.

Pediatr Int 2016 Dec 10;58(12):1261-1265. Epub 2016 Nov 10.

Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.

Background: Recently, a student died of idiopathic ventricular fibrillation in a school where an automated external defibrillator (AED) had been installed. The tragedy could not be prevented because the only AED in the school was installed in the teachers' office, far from the school ground where the accident took place. This prompted establishment of a multiple AED system in schools. The aim of this study was to analyze the efficacy of the multiple AED system to prevent sudden death in school-aged children.

Methods: Assumed accident sites consisted of the school ground, gymnasium, Judo and Kendo hall, swimming pool, and classrooms on the first and the fourth floor. Multiple AED were installed in the teachers' office, gymnasium, some classrooms, and also provided as a portable AED in a rucksack. The time from the accident site to the teachers' office for single AED, and from the accident site to the nearest AED for multiple AED, was calculated.

Results: The AED retrieval time was significantly shorter in 55 elementary schools and in 29 junior high schools when multiple AED were installed compared with single AED. Except for the classroom on the fourth floor, the number of people who took >120 s to bring the AED to the accident site was lower when multiple AED were installed compared with the single AED.

Conclusion: Multiple AED provided in appropriate sites can reduce the time to reach the casualty and hence prevent sudden death in school-aged children.
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http://dx.doi.org/10.1111/ped.13143DOI Listing
December 2016

Diabetic mice exhibited a peculiar alteration in body composition with exaggerated ectopic fat deposition after muscle injury due to anomalous cell differentiation.

J Cachexia Sarcopenia Muscle 2016 05 2;7(2):213-24. Epub 2015 Jun 2.

Department of Molecular Cardiovascular Biology and Pharmacology Ehime University, Graduate School of Medicine Tohon Ehime 791-0295 Japan.

Background: Sarcopenic obesity, age-related muscle loss, which is compensated by an increase in fat mass, impairs quality of life in elderly people. Although the increase in intramuscular fat is associated with decreased insulin sensitivity and increased metabolic risk factors, the origin of diabetes-associated intramuscular fat has not been elucidated. Here, we investigated intramuscular fat deposition using a muscle injury model in type 2 diabetic mice.

Methods: Male 8-week-old C57BL/6 and 8-week-old and 26-week-old KKAy underwent intramuscular injection of cardiotoxin (Ctx) (100 μL/10 μM) into the tibialis anterior (TA) muscles. After 2 weeks, the muscles were removed and evaluated.

Results: KKAy exhibited impaired muscle regeneration and ectopic fat deposition. Such impairment was more marked in older KKAy. These changes were also observed in another diabetic mouse model, db/db and diet-induced obese mice but not in streptozocin-induced diabetic mice. Deposited fat was platelet-derived growth factor (PDGF) receptor alpha positive and its cytoskeleton was stained with Masson's trichrome, indicating it to be of fibro-adipocyte progenitor cell origin. Expression of a myogenic marker, myoD, was lower and that of PDGF receptor alpha and CCAAT/enhancer binding protein (CEBP) alpha was higher in Ctx-injured TA of KKAy compared with that of C57BL/6. Peroxisome proliferator-activated receptor γ (PPARγ) was highly expressed in fat-forming lesions in older KKAy. Treatment with all-trans retinoic acid prevented the formation of intramuscular fat; however, treatment with GW9662, a PPARγ antagonist, increased the fibrotic change in muscle.

Conclusions: Diabetic mice showed impaired muscle regeneration with fat deposition, suggesting that diabetes may enhance sarcopenic obesity through a mechanism involving anomalous fibro-adipocyte progenitor cell differentiation.
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http://dx.doi.org/10.1002/jcsm.12044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864245PMC
May 2016

Angiotensin II Type 2 Receptor Inhibits Vascular Intimal Proliferation With Activation of PPARγ.

Am J Hypertens 2016 06 15;29(6):727-36. Epub 2015 Oct 15.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Tohon, Ehime, Japan;

Background: Angiotensin II type 2 (AT2) receptor stimulation could exert beneficial effects on vascular remodeling. Previously, we reported that AT2 receptor stimulation ameliorated insulin resistance in diabetic mice accompanied by PPARγ activation which also plays a variety of crucial roles in the vasculature. Therefore, this study aimed to investigate the vascular protective effect of the AT2 receptor with activation of PPARγ involving AT2 receptor-interacting protein (ATIP).

Methods And Results: Vascular injury was induced by polyethylene-cuff placement around the femoral artery in C57BL/6J mice. Treatment with compound 21 (C21), an AT2 receptor agonist, decreased neointimal formation, cell proliferation, and the mRNA levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF)-α, and interleukin-1β, and phosphorylation of nuclear factor-kappa B, and increased PPARγ DNA-binding activity in the injured artery, whereas these inhibitory effects of C21 were attenuated by co-treatment with a PPARγ antagonist, GW9662. Treatment of vascular smooth muscle cells (VSMC) with C21 prepared from smAT2 transgenic mice, which highly express the AT2 receptor in VSMC, increased both PPARγ activity and its DNA-binding activity determined by dual-luciferase assay and electrophoresis mobility shift assay (EMSA), respectively. We observed that ATIP was involved in PPARγ complex formation, and that transfection of siRNA of ATIP1 attenuated the AT2 receptor-mediated increase in PPARγ activity in VSMC. In response to AT2 receptor stimulation, ATIP was translocated from the plasma membrane to the nucleus.

Conclusions: Our results suggest a new mechanism by which AT2 receptor stimulation activates PPARγ, thereby resulting in amelioration of vascular intimal proliferation, and that ATIP plays an important role in AT2 receptor-mediated PPARγ activation.
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http://dx.doi.org/10.1093/ajh/hpv168DOI Listing
June 2016

Pre-treatment with LCZ696, an orally active angiotensin receptor neprilysin inhibitor, prevents ischemic brain damage.

Eur J Pharmacol 2015 Sep 6;762:293-8. Epub 2015 Jun 6.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University Graduate School of Medicine, Tohon, Ehime 791-0295, Japan.

Angiotensin II receptor blockers (ARBs) are known to prevent ischemic brain damage after stroke. Natriuretic peptides, which are increased by a neprilysin inhibitor, are also reported to protect against brain damage. Therefore, we investigated the possible protective effect of valsartan (VAL) compared with LCZ696 (VAL+ neprilysin inhibitor; 1:1) after middle cerebral artery (MCA) occlusion. Eight-week-old male C57BL/6J mice were treated with VAL (3mg/kg per day) or LCZ696 (6mg/kg per day) for 2 weeks before MCA occlusion. Blood pressure and heart rate were measured by telemetry. Cerebral blood flow (CBF) was determined by laser-Doppler flowmetry. Ischemic area was evaluated by triphenytetrasodium chloride staining, and oxidative stress was determined by dihydroethidium staining. Blood pressure and heart rate were not significantly different before and after treatment. Pre-treatment with LCZ696 or VAL reduced the ischemic area, and this effect of LCZ696 was more marked than that of VAL pre-treatment. The decrease in CBF in the peripheral region of the ischemic area was significantly attenuated by pre-treatment with LCZ696 or VAL, without any significant effect on CBF in the core region. VAL or LCZ696 pre-treatment significantly decreased the increase of superoxide anion production in the cortex on the ischemic side. However, no significant difference in CBF and superoxide anion production was observed between VAL and LCZ696 pre-treatment. The preventive effect of LCZ696 on ischemic brain damage after stroke was more marked than that of VAL. LCZ696 could be used as a new approach to prevent brain damage after stroke. (246 words).
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http://dx.doi.org/10.1016/j.ejphar.2015.05.059DOI Listing
September 2015

Successful treatment by coil embolization for infantile hemangioma with Kasabach-Meritt syndrome of newborn.

Pediatr Int 2015 Aug 4;57(4):738-41. Epub 2015 Jun 4.

Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.

Infantile hemangioma (IH) is the most common tumor of infancy, and it sometimes associated with Kasabach-Meritt syndrome (KMS) characterized by anemia, intraperitoneal hemorrhage secondary to rupture, coagulopathy, jaundice, and vascular malformations involving the brain, skin, gut, and other organs. Here, we report two newborn patients having IH with KMS at birth. The first patient had a giant hemangioma in the liver, which was successfully treated with i.v. corticosteroid and coil embolization. The second patient had a large hemangioma of the right axillary region, which was also successfully treated with i.v. corticosteroid, beta-blocker, coil embolization and local irradiation. All symptoms were controlled without any side-effects in both patients. According to these findings, combination therapy including coil embolization and corticosteroid is effective for IH patients with KMS. The indications for and timing of coil embolization should be determined further cases have been accumulated.
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http://dx.doi.org/10.1111/ped.12618DOI Listing
August 2015

Low-Protein Diet-Induced Fetal Growth Restriction Leads to Exaggerated Proliferative Response to Vascular Injury in Postnatal Life.

Am J Hypertens 2016 Jan 22;29(1):54-62. Epub 2015 May 22.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Tohon, Ehime, Japan;

Background: We investigated the effects of fetal growth restriction (FGR) induced by maternal protein restriction on inflammatory vascular remodeling using a cuff-induced vascular injury mouse model.

Methods: Dams (C57BL/6J strain mice) were fed an isocaloric diet containing 20% protein (normal protein; NP) or 8% protein (low protein; LP) from 10 weeks of age until delivery. On the day of delivery, all dams were returned to the NP diet. After weaning, offspring were fed the NP diet. When offspring were 10 weeks of age, vascular injury was induced by polyethylene cuff placement around the femoral artery.

Results: Birth weight in offspring from dams fed LP until delivery (LPO) was significantly lower, but body weight was the same at 2 weeks after birth compared with that in NP offspring (NPO). Arterial blood pressure at 12 weeks of age did not differ between LPO and NPO. Neointima formation was exaggerated in LPO compared with NPO and associated with an increase in cell proliferation assessed by proliferating cell nuclear antigen (PCNA) staining index. Moreover, LPO showed enhanced expression of monocyte chemotactic protein-1, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and production of superoxide anion in the injured artery. Moreover, mRNA expression of isoforms of NAD(P)H oxidase subunits such as p22phox, p40phox, p47phox, p67phox, gp91phpx, and Rac1 in the injured arteries were enhanced in LPO. Furthermore, HIF-1α expression was increased in LPO compared with that in NPO.

Conclusions: These results suggest that maternal low-protein diet-induced FGR increases susceptibility of the vasculature to postnatal injury.
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http://dx.doi.org/10.1093/ajh/hpv072DOI Listing
January 2016

Angiotensin II type 2 receptor signaling affects dopamine levels in the brain and prevents binge eating disorder.

J Renin Angiotensin Aldosterone Syst 2015 Dec 9;16(4):749-57. Epub 2015 Mar 9.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University Graduate School of Medicine, Japan.

Introduction: Binge eating disorder (BED) is associated with dopaminergic activation as food reward, resulting in metabolism-related disorders. Stimulation of angiotensin type 2 (AT2) receptor is reported to inhibit dopamine synthesis. We investigated the possible roles of AT2 receptor-mediated dopamine regulation in the pathogenesis of BED.

Materials And Methods: Male C57BL/6 mice, type 2 diabetic (KKAy) mice and AT2 receptor-null (AT2KO) mice at eight weeks old were treated with AT2 receptor agonist, compound 21 (C21) or saline for two weeks. Mice were subjected to fasting for two days followed by re-feeding for seven days.

Results: Treatment with C21 attenuated the rebound proportion of body weight, food intake and water intake in KKAy mice, but not in C57BL/6 and AT2KO mice. Dopamine concentration in the striatum was further increased by fasting in KKAy and AT2KO mice. Administration of C21 significantly attenuated this fasting-induced increase in dopamine level only in KKAy mice. Dopamine receptor D1, D2 expression in the substantia nigra were markedly lower in KKAy mice compared with C57BL/6 mice, while administration of C21 increased their expression in KKAy mice.

Conclusions: Our study suggests that AT2 receptor stimulation may be a new therapeutic approach to improve eating disorder associated with dopamine resistance.
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http://dx.doi.org/10.1177/1470320315573680DOI Listing
December 2015

Direct angiotensin II type 2 receptor stimulation by compound 21 prevents vascular dementia.

J Am Soc Hypertens 2015 Apr 24;9(4):250-6. Epub 2015 Jan 24.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Tohon, Ehime, Japan. Electronic address:

Angiotensin II type 2 (AT(2)) receptor activation has been reported to play a role in cognitive function, although its detailed mechanisms and pathologic significance are not fully understood. We examined the possibility that direct AT(2) receptor stimulation by compound 21 (C21) could prevent cognitive decline associated with hypoperfusion in the brain.We employed a bilateral common carotid artery stenosis (BCAS) model in mice as a model of vascular dementia. The Morris water maze task was performed 6 weeks after BCAS operation. Azilsartan (0.1 mg/kg/day) or C21 (10 μg/kg/day) was administered from 1 week before BCAS. Cerebral blood flow (CBF) and inflammatory cytokine levels were also determined. Wild-type (WT) mice showed significant prolongation of escape latency after BCAS, and this cognitive impairment was attenuated by pretreatment with azilsartan. Cognitive impairment was more marked in AT(2) receptor knockout (AT(2)KO) mice, and the preventive effect of azilsartan on cognitive decline was weaker in AT(2)KO mice than in WT mice, suggesting that the improvement of cognitive decline by azilsartan may involve stimulation of the AT(2) receptor. The significant impairment of spatial learning after BCAS in WT mice was attenuated by C21 treatment. The decrease in CBF in the BCAS-treated group was blunted by C21 treatment, and the increase in TNF-α and MCP-1 mRNA expression after BCAS was attenuated by C21 treatment. These findings indicate that direct AT(2) receptor stimulation attenuates ischemic vascular dementia induced by hypoperfusion at least in part through an increase in CBF, and a reduction of inflammation.
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http://dx.doi.org/10.1016/j.jash.2015.01.010DOI Listing
April 2015

Drinking citrus fruit juice inhibits vascular remodeling in cuff-induced vascular injury mouse model.

PLoS One 2015 18;10(2):e0117616. Epub 2015 Feb 18.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Tohon, Ehime, Japan.

Citrus fruits are thought to have inhibitory effects on oxidative stress, thereby attenuating the onset and progression of cancer and cardiovascular disease; however, there are few reports assessing their effect on vascular remodeling. Here, we investigated the effect of drinking the juice of two different citrus fruits on vascular neointima formation using a cuff-induced vascular injury mouse model. Male C57BL6 mice were divided into five groups as follows: 1) Control (water) (C), 2) 10% Citrus unshiu (CU) juice (CU10), 3) 40% CU juice (CU40), 4) 10% Citrus iyo (CI) juice (CI10), and 5) 40% CI juice (CI40). After drinking them for 2 weeks from 8 weeks of age, cuff injury was induced by polyethylene cuff placement around the femoral artery. Neointima formation was significantly attenuated in CU40, CI10 and CI40 compared with C; however, no remarkable preventive effect was observed in CU10. The increases in levels of various inflammatory markers including cytokines such as monocyte chemotactic protein-1, interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in response to vascular injury did not differ significantly between C, CU10 and CI10. The increases in cell proliferation and superoxide anion production were markedly attenuated in CI10, but not in CU10 compared with C. The increase in phosphorylated ERK expression was markedly attenuated both in CU10 and CI10 without significant difference between CU10 and CI10. Accumulation of immune cells did not differ between CU10 and CI10. These results indicate that drinking citrus fruit juice attenuates vascular remodeling partly via a reduction of oxidative stress. Interestingly, the preventive efficacy on neointima formation was stronger in CI than in CU at least in part due to more prominent inhibitory effects on oxidative stress by CI.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117616PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334235PMC
November 2015

Procalcitonin as a marker of respiratory disorder in neonates.

Pediatr Int 2015 Apr 11;57(2):263-8. Epub 2014 Dec 11.

Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.

Background: Serum procalcitonin (PCT) increases in various respiratory disorders such as acute respiratory distress syndrome. Elevated PCT is also observed in healthy neonates. In this study, we investigated whether PCT is a good marker of respiratory disorder in neonates.

Methods: A total of 155 neonates with or without respiratory disorder, were eligible for the study. PCT was measured on electrochemiluminescence immunoassay. Each neonate was allocated to the non-respiratory disorder (control) group (n = 95), or a respiratory disorder group (n = 60). PCT was compared between the groups, and association with other markers, including C-reactive protein (CRP) and white blood cell (WBC) count, was analyzed.

Results: Of the 60 neonates in the respiratory disorder group, 39, 10, five, one, two, two, and one neonates had transient tachypnea of the newborn, respiratory distress syndrome, air leak syndrome, meconium aspiration syndrome, 18-trisomy, neonatal asphyxia, and congenital diaphragmatic hernia, respectively. Mean PCT, CRP and WBC count in the respiratory disorder group were 9.01 ng/mL, 0.26 mg/dL, and 16,100 cells/μL, respectively. The area under the curve obtained for PCT in distinguishing between the respiratory disorder and control groups was 0.85 (sensitivity, 66.7%; specificity, 93.0%; optimum cut-off, 3.73 ng/mL), that for CRP was 0.72 (sensitivity, 75.0%; specificity, 64.6%; optimum cut-off, 0.14 mg/dL), and for WBC it was 0.44 (sensitivity, 60.0%; specificity, 29.6%; optimum cut-off, 15,000 cells/μL).

Conclusions: PCT is more susceptible, as a diagnostic parameter of infection, to the effect of respiratory disturbance than CRP and WBC.
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http://dx.doi.org/10.1111/ped.12505DOI Listing
April 2015

Role of angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis in the hypotensive effect of azilsartan.

Hypertens Res 2014 Jul 6;37(7):616-20. Epub 2014 Mar 6.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Shitsukawa, Ehime, Japan.

The possible counteracting effect of angiotensin (Ang)-converting enzyme (ACE)2/Ang-(1-7)/Mas axis against the ACE/Ang II/Ang II type 1 (AT1) receptor axis in blood pressure control has been previously described. We examined the possibility that this pathway might be involved in the anti-hypertensive effect of a newly developed AT1 receptor blocker (ARB), azilsartan, and compared azilsartan's effects with those of another ARB, olmesartan. Transgenic mice carrying the human renin and angiotensinogen genes (hRN/hANG-Tg) were given azilsartan or olmesartan. Systolic and diastolic blood pressure, as determined by radiotelemetry, were significantly higher in hRN/hANG-Tg mice than in wild-type (WT) mice. Treatment with azilsartan or olmesartan (1 or 5 mg kg(-1) per day) significantly decreased systolic and diastolic blood pressure, and the blood pressure-lowering effect of azilsartan was more marked than that of olmesartan. The urinary Na concentration decreased in an age-dependent manner in hRN/hANG-Tg mice. Administration of azilsartan or olmesartan increased urinary Na concentration, and this effect was weaker with olmesartan than with azilsartan. Azilsartan decreased ENaC-α mRNA expression in the kidney and decreased the ratio of heart to body weight. Olmesartan had a similar but less-marked effect. ACE2 mRNA expression was lower in the kidneys and hearts of hRN/hANG-Tg mice than in WT mice. This decrease in ACE2 mRNA expression was attenuated by azilsartan, but not by olmesartan. These results suggest that the hypotensive and anti-hypertrophic effects of azilsartan may involve activation of the ACE2/Ang-(1-7)/Mas axis with AT1 receptor blockade.
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http://dx.doi.org/10.1038/hr.2014.49DOI Listing
July 2014

Direct stimulation of angiotensin II type 2 receptor initiated after stroke ameliorates ischemic brain damage.

Am J Hypertens 2014 Aug 26;27(8):1036-44. Epub 2014 Feb 26.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University Graduate School of Medicine, Tohon, Ehime, Japan.

Background: Stroke is a leading cause of death and disability; however, meta-analysis of randomized controlled trials of blood pressure-lowering drugs in acute stroke has shown no definite evidence of a beneficial effect on functional outcome. Accumulating evidence suggests that angiotensin II type 1 receptor blockade with angiotensin II type 2 (AT2) receptor stimulation could contribute to protection against ischemic brain damage. We examined the possibility that direct AT2 receptor stimulation by compound 21 (C21) initiated even after stroke can prevent ischemic brain damage.

Methods: Stroke was induced by middle cerebral artery (MCA) occlusion, and the area of cerebral infarction was measured by magnetic resonant imaging. C21 (10 µg/kg/day) treatment was initiated immediately after MCA occlusion by intraperitoneal injection followed by treatment with C21 once daily.

Results: We observed that ischemic area was enlarged in a time dependent fashion and decreased on day 5 after MCA occlusion. Treatment with C21 initiated after MCA occlusion significantly reduced the ischemic area, with improvement of neurological deficit in a time-dependent manner without affecting blood pressure. The decrease of cerebral blood flow after MCA occlusion was also ameliorated by C21 treatment. Moreover, treatment with C21 significantly attenuated superoxide anion production and expression of proinflammatory cytokines, monocyte chemoattractant protein 1, and tumor necrosis factor α. Interestingly, C21 administration significantly decreased blood-brain barrier permeability and cerebral edema on the ischemic side.

Conclusions: These results provide new evidence that direct AT2 receptor stimulation with C21 is a novel therapeutic approach to prevent ischemic brain damage after acute stroke.
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http://dx.doi.org/10.1093/ajh/hpu015DOI Listing
August 2014

Possible role of angiotensin-converting enzyme 2 and activation of angiotensin II type 2 receptor by angiotensin-(1-7) in improvement of vascular remodeling by angiotensin II type 1 receptor blockade.

Hypertension 2014 Mar 30;63(3):e53-9. Epub 2013 Dec 30.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Shitsukawa, Tohon, Ehime 791-0295, Japan.

Cross talk between the angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis and the ACE2/Ang-(1-7)/Mas axis plays a role in the pathogenesis of cardiovascular remodeling. Furthermore, possible stimulation of the Ang II type 2 (AT2) receptor by Ang-(1-7) has been highlighted as a new pathway. Therefore, we examined the possibility of whether the ACE2/Ang-(1-7)/Mas axis and Ang-(1-7)/AT2 receptor axis are involved in the inhibitory effects of AT1 receptor blockers on vascular remodeling. Wild-type, Mas-knockout, and AT2 receptor knockout mice were used in this study. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. Some mice were treated with azilsartan, an AT1 receptor blocker, or Ang-(1-7). Neointimal formation 2 weeks after cuff placement was more marked in Mas-knockout mice compared with wild-type mice. Treatment with azilsartan or Ang-(1-7) attenuated neointimal area, vascular smooth muscle cell proliferation, increases in the mRNA levels of monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-1β, and superoxide anion production in the injured artery; however, these inhibitory effects of azilsartan and Ang-(1-7) were less marked in Mas-knockout mice. Administration of azilsartan or Ang-(1-7) attenuated the decrease in ACE2 mRNA and increased AT2 receptor mRNA but did not affect AT1 receptor mRNA or the decrease in Mas mRNA. The inhibitory effect of Ang-(1-7) on neointimal formation was less marked in AT2 receptor knockout mice compared with wild-type mice. These results suggest that blockade of the AT1 receptor by azilsartan could enhance the activities of the ACE2/Ang-(1-7)/Mas axis and ACE2/Ang-(1-7)/AT2 receptor axis, thereby inhibiting neointimal formation.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.113.02426DOI Listing
March 2014

Possible synergistic effect of direct angiotensin II type 2 receptor stimulation by compound 21 with memantine on prevention of cognitive decline in type 2 diabetic mice.

Eur J Pharmacol 2014 Feb 18;724:9-15. Epub 2013 Dec 18.

Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University Graduate School of Medicine, Tohon, Ehime 791-0295, Japan. Electronic address:

Type 2 diabetes mellitus (T2DM) is known to be associated with increased risk of cognitive impairment including Alzheimer disease. Recent studies have suggested an interaction between angiotensin II and N-methyl-d-aspartic acid (NMDA) glutamate receptors. We previously reported that stimulation of the angiotensin II type 2 (AT2) receptor exerts brain protective effects. A newly developed AT2 receptor agonist, compound 21 (C21), has enabled examination of the direct effect of AT2 receptor stimulation in vivo. Accordingly, we examined the possible synergistic effect of C21 and memantine on cognitive impairment in T2DM mice, KKAy. KKAy were divided into four groups; (1) control, (2) treatment with C21 (10 μg/kg/day), (3) treatment with memantine (20mg/kg/day), and (4) treatment with both for 4 weeks, and subjected to Morris water maze tasks. Treatment with C21 or memantine alone at these doses tended to shorten escape latency compared to that in the control group. C21 treatment increased cerebral blood flow (CBF), but memantine did not influence CBF. Treatment with C21 or C21 plus memantine increased hippocampal field-excitatory postsynaptic potential (f-EPSP). Moreover, treatment with memantine or C21 increased acetylcholine level, which was lower in KKAy than in wild-type mice, and C21 plus memantine treatment enhanced memantine or C21-induced acetylcholine secretion. This study provides an insight into new approaches to understand the interaction of angiotensin II and neurotransmitters. We can anticipate a new therapeutic approach against cognitive decline using C21 and memantine.
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http://dx.doi.org/10.1016/j.ejphar.2013.12.015DOI Listing
February 2014

Pulmonary artery banding for neonates and early infants with low body weight.

Tohoku J Exp Med 2011 12;225(4):255-62

Department of Surgery, Division of Pediatric Cardiovascular Surgery, Ehime University School of Medicine, Ehime, Japan.

Open heart surgery for infants with low body weight (BW) remains still a challenge. Pulmonary artery banding (PAB) is a useful surgical palliation for small neonates and early infants with excessive pulmonary blood flow who are unable to withstand a heart surgery. This study retrospectively reviewed neonates and infants who underwent PAB to assess the surgical results and the validity of our PAB. We selected 38 acyanotic infants and neonates and divided them into 2 groups: low BW (< 2.5 kg, n = 15, group L) and normal or high BW (≥ 2.5 kg, n = 23, group NH). The average BW at the time of PAB was 2.8 ± 1.1 kg (range, 1.2-5.8 kg), and the average age at the time of PAB was 41.8 ± 44.8 days (range, 2-151 days). Using a 3-mm-wide polyester tape, we tightened the main pulmonary artery to obtain the circumference of (19 mm + 1 mm for each kg of BW). There was no early death but one late death in each group. Postoperative BW continuously increased 1 month after PAB in both groups, although BW was significantly lower in group L than in group NH. Intracardiac repair (ICR) was accomplished in 31 patients (13 in group L and 18 in group NH) at average ages of 1.5 years, while the remaining 5 patients are awaiting ICR. In conclusion, PAB using our formula for the infants even weighing < 2.5 kg has low mortality and is effective as a bridge to ICR.
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http://dx.doi.org/10.1620/tjem.225.255DOI Listing
December 2011

Novel dominant-negative mutant of GATA3 in HDR syndrome.

J Mol Med (Berl) 2011 Jan 1;89(1):43-50. Epub 2010 Dec 1.

Department of Neonatology, Maternity & Perinatal Care Unit, Ehime University Hospital, Shitsukawa, Toon, Matsuyama, Ehime, 791-0295, Japan.

HDR syndrome is an autosomal dominant disorder characterized by hypoparathyroidism, sensorineural deafness, and renal anomaly caused by mutation of the GATA3 gene located at chromosome 10p15. We report the case of a neonate with HDR syndrome and a novel GATA3 mutation. We performed genetic and functional analysis of GATA3 in this patient and identified a novel heterozygous 1516G> C missense mutation in exon 5, resulting in a cysteine-to-serine substitution at codon 321 (Cys321Ser). Mutated and wild-type GATA3 proteins were expressed at a similar level in vitro, indicating that the mutated GATA3 protein was stable. Luciferase assay revealed that the Cys321Ser-mutated GATA3 lacked transactivation activity due to loss of DNA-binding activity as confirmed by gel shift assay. Moreover, mutated GATA3 exerted a dominant-negative effect over the transactivation activity of wild-type GATA3. These findings indicate that not only haploinsufficiency of GATA3 but also the dominant-negative effect of Cys321Ser-mutated GATA3 might have been responsible for the HDR syndrome phenotype of our patient.
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http://dx.doi.org/10.1007/s00109-010-0702-6DOI Listing
January 2011

Use of a hand-made balloon-expandable covered stent for native coarctation of the aorta in an adult patient: a report of a first case in Japan.

J Cardiol 2010 Nov 21;56(3):287-90. Epub 2010 Aug 21.

Department of Pediatric Cardiology, Stroke & Cardiovascular Center, Ehime University Hospital, Ehime, Japan.

In western countries, the use of a balloon-expandable covered stent is recommended for the treatment of native coarctation of the aorta (CoA) in adult patients because endovascular bare stents cannot completely prevent complications such as aneurysms or aortic rupture. However, such a product that is appropriate and officially approved is not available in Japan. We developed and used a handmade balloon-expandable covered stent in a 32-year-old patient with native CoA and achieved a good outcome. A Palmaz-Schatz stent (XL 10-series 4010; Johnson & Johnson, Warren, NJ, USA) was covered with an Ube woven-graft (WST series; 18 mm across; Ube Junken Medical, Tokyo, Japan). Because the stent shortens when dilated, one end of the graft was firmly sutured to one end of the stent, whereas the other end of the graft was stitched loosely to the other end of the stent so that it could slide along the struts of the stent to accommodate foreshortening. After meticulous in vitro simulations, the covered stent was implanted with right ventricular overdrive pacing. No complications were observed, and the pressure gradient disappeared. These results indicate that angioplasty using a balloon-expandable covered stent is highly safe and effective for correcting native CoA in adult patients and hopefully in children.
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http://dx.doi.org/10.1016/j.jjcc.2010.06.005DOI Listing
November 2010

Successful stenting of the ductus venosus in 2 neonates with asplenia syndrome complicated by infracardiac type total anomalous pulmonary venous connection.

J Cardiol Cases 2010 Jun 3;1(3):e129-e132. Epub 2009 Dec 3.

Department of Pediatrics, Ehime University Graduate School of Medicine, Ehime, Japan.

In the neonatal period, the surgical mortality of palliation is extremely high for asplenia syndrome complicated by single ventricle combined with total anomalous pulmonary venous connection (TAPVC). Recently, stent implantation for the pulmonary venous drainage route soon after birth has been used instead of surgery to prevent pulmonary venous occlusion and to maintain stable hemodynamics in the neonatal period or in early infancy. Here, we successfully implanted stents in the ductus venosus (DV) in 2 neonates with asplenia syndrome complicated by infracardiac type TAPVC. The first patient was a 3-day-old male neonate with severe cyanosis. Immediately after TAPVC was diagnosed, we implanted a stent in the DV. The second patient was a 0-day-old female neonate. She was diagnosed as TAPVC by fetal echocardiogram. After the scheduled delivery, a stent was successfully implanted. We believe that stent implantation in the DV in the neonatal period is effective and less invasive than surgery in patients with infracardiac type TAPVC.
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http://dx.doi.org/10.1016/j.jccase.2009.10.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6264943PMC
June 2010