Publications by authors named "Yuuki Shimizu"

60 Publications

LPL/AQP7/GPD2 promotes glycerol metabolism under hypoxia and prevents cardiac dysfunction during ischemia.

FASEB J 2021 Dec;35(12):e22048

Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan.

In the heart, fatty acid is a major energy substrate to fuel contraction under aerobic conditions. Ischemia downregulates fatty acid metabolism to adapt to the limited oxygen supply, making glucose the preferred substrate. However, the mechanism underlying the myocardial metabolic shift during ischemia remains unknown. Here, we show that lipoprotein lipase (LPL) expression in cardiomyocytes, a principal enzyme that converts triglycerides to free fatty acids and glycerol, increases during myocardial infarction (MI). Cardiomyocyte-specific LPL deficiency enhanced cardiac dysfunction and apoptosis following MI. Deficiency of aquaporin 7 (AQP7), a glycerol channel in cardiomyocytes, increased the myocardial infarct size and apoptosis in response to ischemia. Ischemic conditions activated glycerol-3-phosphate dehydrogenase 2 (GPD2), which converts glycerol-3-phosphate into dihydroxyacetone phosphate to facilitate adenosine triphosphate (ATP) synthesis from glycerol. Conversely, GPD2 deficiency exacerbated cardiac dysfunction after acute MI. Moreover, cardiomyocyte-specific LPL deficiency suppressed the effectiveness of peroxisome proliferator-activated receptor alpha (PPARα) agonist treatment for MI-induced cardiac dysfunction. These results suggest that LPL/AQP7/GPD2-mediated glycerol metabolism plays an important role in preventing myocardial ischemia-related damage.
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http://dx.doi.org/10.1096/fj.202100882RDOI Listing
December 2021

DJ-1 attenuates the glycation of mitochondrial complex I and complex III in the post-ischemic heart.

Sci Rep 2021 Sep 30;11(1):19408. Epub 2021 Sep 30.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, 101 Woodruff Circle, Atlanta, GA, 30322, USA.

DJ-1 is a ubiquitously expressed protein that protects cells from stress through its conversion into an active protease. Recent work found that the active form of DJ-1 was induced in the ischemic heart as an endogenous mechanism to attenuate glycative stress-the non-enzymatic glycosylation of proteins. However, specific proteins protected from glycative stress by DJ-1 are not known. Given that mitochondrial electron transport proteins have a propensity for being targets of glycative stress, we investigated if DJ-1 regulates the glycation of Complex I and Complex III after myocardial ischemia-reperfusion (I/R) injury. Initial studies found that DJ-1 localized to the mitochondria and increased its interaction with Complex I and Complex III 3 days after the onset of myocardial I/R injury. Next, we investigated the role DJ-1 plays in modulating glycative stress in the mitochondria. Analysis revealed that compared to wild-type control mice, mitochondria from DJ-1 deficient (DJ-1 KO) hearts showed increased levels of glycative stress following I/R. Additionally, Complex I and Complex III glycation were found to be at higher levels in DJ-1 KO hearts. This corresponded with reduced complex activities, as well as reduced mitochondrial oxygen consumption ant ATP synthesis in the presence of pyruvate and malate. To further determine if DJ-1 influenced the glycation of the complexes, an adenoviral approach was used to over-express the active form of DJ-1(AAV9-DJ1ΔC). Under I/R conditions, the glycation of Complex I and Complex III were attenuated in hearts treated with AAV9-DJ1ΔC. This was accompanied by improvements in complex activities, oxygen consumption, and ATP production. Together, this data suggests that cardiac DJ-1 maintains Complex I and Complex III efficiency and mitochondrial function during the recovery from I/R injury. In elucidating a specific mechanism for DJ-1's role in the post-ischemic heart, these data break new ground for potential therapeutic strategies using DJ-1 as a target.
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http://dx.doi.org/10.1038/s41598-021-98722-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8484662PMC
September 2021

Treatment with adipose-derived regenerative cells enhances ischemia-induced angiogenesis via exosomal microRNA delivery in mice.

Nagoya J Med Sci 2021 Aug;83(3):465-476

Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan.

Adipose-derived regenerative cells (ADRCs), mesenchymal stem/progenitor cells from subcutaneous adipose tissue, have been shown to stimulate angiogenesis in hind limb ischemia, an effect attributed to paracrine action on endothelial cells (ECs) in mice. Despite promising therapeutic effects, the relevant molecules promoting neovascularization in this setting have not been fully elucidated. Extracellular vesicles, crucial mediators of intercellular communication, are recognized as a new therapeutic modality for regenerative medicine. Here, we found that GW4869, an exosome biogenesis inhibitor targeting neutral sphingomyelinase, impaired ADRCs-mediated angiogenesis and improvement of blood perfusion in a murine hind limb ischemia model. In addition, while the supernatant of ADRCs induced murine EC migration, this effect was attenuated by pre-treatment with GW4869. RNA analysis revealed that treatment of ADRCs with GW4869 reduced the expression of microRNA-21 (miR-21), miR-27b, miR-322, and let-7i in ADRCs-derived exosomes. Furthermore, the exosomes derived from GW4869-treated ADRCs induced the expression of the miR-21 targets and , and the miR-322 target , in ECs. These findings suggest that several miRNAs in ADRCs-derived exosomes contribute to angiogenesis and improvement of blood perfusion in a murine hind limb ischemia model.
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http://dx.doi.org/10.18999/nagjms.83.3.465DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8438007PMC
August 2021

Adverse Effect of Circadian Rhythm Disorder on Reparative Angiogenesis in Hind Limb Ischemia.

J Am Heart Assoc 2021 08 5;10(16):e020896. Epub 2021 Aug 5.

Department of Cardiology Nagoya University Graduate School of Medicine Nagoya Japan.

Background Circadian rhythm disorders, often seen in modern lifestyles, are a major social health concern. The aim of this study was to examine whether circadian rhythm disorders would influence angiogenesis and blood perfusion recovery in a mouse model of hind limb ischemia. Methods and Results A jet-lag model was established in C57BL/6J mice using a light-controlled isolation box. Control mice were kept at a light/dark 12:12 (12-hour light and 12-hour dark) condition. Concentrations of plasma vascular endothelial growth factor and circulating endothelial progenitor cells in control mice formed a circadian rhythm, which was diminished in the jet-lag model (<0.05). The jet-lag condition deteriorated tissue capillary formation (<0.001) and tissue blood perfusion recovery (<0.01) in hind limb ischemia, which was associated with downregulation of vascular endothelial growth factor expression in local ischemic tissue and in the plasma. Although the expression of clock genes (ie, , , and ) in local tissues was upregulated after ischemic injury, the expression levels of cryptochrome (Cry) 1 and Cry2 were inhibited by the jet-lag condition. Next, and double-knockout mice were examined for blood perfusion recoveries and a reparative angiogenesis. and double-knockout mice revealed suppressed capillary density (<0.001) and suppressed tissue blood perfusion recovery (<0.05) in the hind limb ischemia model. Moreover, knockdown of in human umbilical vein endothelial cells was accompanied by increased expression of and decreased expression of . This was associated with decreased proliferative capacity, migration ability, and tube formation ability of human umbilical vein endothelial cells, respectively, leading to impairment of angiogenesis. Conclusions Our data suggest that circadian rhythm disorder deteriorates reparative ischemia-induced angiogenesis and that maintenance of circadian rhythm plays an important role in angiogenesis.
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http://dx.doi.org/10.1161/JAHA.121.020896DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8475022PMC
August 2021

Omentin attenuates angiotensin II-induced abdominal aortic aneurysm formation in apolipoprotein-E knockout mice.

Cardiovasc Res 2021 May 29. Epub 2021 May 29.

Department of Molecular Medicine and Cardiology, Nagoya University Graduate School of Medicine.

Aims: Abdominal aortic aneurysm (AAA) is an increasing and life-threatening disease. Obesity contributes to an increased risk of AAA. Omentin is a circulating adipokine, which is downregulated in obese complications. Here we examined whether omentin could modulate angiotensin (Ang) II-induced AAA formation in apolipoprotein-E knockout (apoE-KO) mice.

Methods And Results: ApoE-KO mice were crossed with transgenic mice expressing the human omentin gene in fat tissue (OMT-Tg mice) to generate ApoE-KO/OMT-Tg mice. ApoE-KO/OMT-Tg and apoE-KO mice were subjected to continuous Ang II infusion by using osmotic mini pumps. ApoE-KO/OMT-Tg mice exhibited a lower incidence of AAA formation and a reduced maximal diameter of AAA compared with apo-E KO mice. ApoE-KO/OMT-Tg mice showed attenuated disruption of medial elastic fibers in response to Ang II compared with apo-E KO mice. ApoE-KO/OMT-Tg mice also displayed reduced expression levels of matrix metalloproteinase (MMP) 9, MMP2 and pro-inflammatory genes in aortic walls compared with apo-E KO mice. Furthermore, systemic administration of omentin also attenuated AAA formation and disruption of medial elastic fibers in response to Ang II in apoE-KO mice. Treatment of human monocyte-derived macrophages with omentin protein attenuated expression of MMP9 and pro-inflammatory mediators, and MMP9 activation after stimulation with lipopolysaccharide (LPS). Treatment of human vascular smooth muscle cells with omentin protein reduced expression and activation of MMP2 after stimulation with tumor necrosis factor α. Omentin treatment increased phosphorylation levels of Akt in human macrophages and vascular smooth muscle cells. The suppressive effects of omentin on MMP9 and MMP2 expression were reversed by inhibition of integrin-αVβ3/PI3-kinase/Akt signaling in macrophages and vascular smooth muscle cells, respectively.

Conclusion: These data suggest that omentin acts as an adipokine that can attenuate Ang II-induced development of AAA through suppression of MMP9 and MMP2 expression and inflammatory response in the vascular wall.
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http://dx.doi.org/10.1093/cvr/cvab179DOI Listing
May 2021

Important Role of Concomitant Lymphangiogenesis for Reparative Angiogenesis in Hindlimb Ischemia.

Arterioscler Thromb Vasc Biol 2021 06 29;41(6):2006-2018. Epub 2021 Apr 29.

Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (Z.P., Y.S., K.T., J.S., R.H., K.K., Y.F., K.U., K.O., M.T., Y.K.B., N.O., R.S., T.M.).

[Figure: see text].
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http://dx.doi.org/10.1161/ATVBAHA.121.316191DOI Listing
June 2021

Rationale and Design of Therapeutic Angiogenesis by Cell Transplantation Using Adipose-Derived Regenerative Cells in Patients With Critical Limb Ischemia - TACT-ADRC Multicenter Trial.

Circ Rep 2020 Aug 8;2(9):531-535. Epub 2020 Aug 8.

Department of Cardiology, Nagoya University Graduate School of Medicine Nagoya Japan.

Despite the growing knowledge regarding optimal treatments for critical limb ischemia (CLI), there are still a considerable number of patients who have to undergo major limb amputation. Intramuscular injection of autologous adipose-derived regenerative cells (ADRCs) in these patients has shown therapeutic potential in improving tissue ischemia, in both preclinical and initial pilot studies. Here, we present a clinical protocol for ADRCs use in a multicenter trial. The TACT-ADRC multicenter trial is a prospective, interventional, single-arm, open-labeled study at 8 hospitals in Japan, investigating the safety and feasibility of intramuscular injections of ADRCs and testing the hypothesis that this treatment promotes neovascularization and improves major amputation-free survival rates in patients with CLI who have no other treatment option. 40 patients with CLI will be enrolled and followed up from November 2015 to November 2020. Freshly isolated autologous ADRCs will be injected into the target ischemic limbs. Survival rate, adverse events, major limb amputation, ulcer size, 6-min walking distance, numerical rating scale, ankle-brachial pressure index, skin perfusion pressure and digital subtraction angiography will be evaluated at baseline and during 6 months' follow-up. This trial will demonstrate whether implantation of autologous ADRCs is a safe and effective method for therapeutic angiogenesis, resulting in an improvement in major amputation-free survival rates in patients with CLI.
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http://dx.doi.org/10.1253/circrep.CR-20-0055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7819646PMC
August 2020

No influence on tumor growth by intramuscular injection of adipose-derived regenerative cells: safety evaluation of therapeutic angiogenesis with cell therapy.

Am J Physiol Heart Circ Physiol 2021 01 13;320(1):H447-H457. Epub 2020 Nov 13.

Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Therapeutic angiogenesis with autologous stem/progenitor cells is a promising novel strategy for treatment of severe ischemic diseases. Human clinical trials utilizing autologous adipose-derived regenerative cells (ADRCs) have not reported treatment-related critical adverse effects thus far. However, there is still a large knowledge gap regarding whether treatment of ischemic diseases with angiogenic therapy using ADRCs would promote unfavorable angiogenesis associated with tumors in vivo. Herein, we addressed this clinical question using a mouse hindlimb ischemia (HLI) and simultaneous remote tumor implantation model. C57BL/6J background wild-type mice were injected with murine B16F10 melanoma cells on their back, 1 day before ischemic surgery. These mice were subjected to surgical unilateral hindlimb ischemia, followed by ADRC implantation or PBS injection into the hindlimb ischemic muscles on the next day. Intramuscular implantation of ADRCs enhanced tissue capillary density and blood flow examined by a laser Doppler blood perfusion analysis in hind limb. However, this therapeutic regimen for ischemic limb using ADRCs did not affect remote melanoma growth nor the density of its feeder artery, angiogenesis, and lymphatic vessels compared with the PBS group. In addition, no distant metastases were detected in any of the mice regardless of the group. In conclusion, local implantation of ADRCs promotes angiogenesis in response to tissue ischemia in the hindlimb without promoting remote tumor growth and related angio/lymphangiogenesis. Therapeutic angiogenesis to the ischemic hindlimb using ADRCs seems to be safe regarding remote tumor growth. In this study, we demonstrated that local injection of ADRCs can promote angiogenesis in response to tissue ischemia without promoting remote tumor growth in a mouse model. Our findings indicate that therapeutic angiogenesis to the ischemic hindlimb using ADRCs seems to be safe regarding remote tumor growth.
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http://dx.doi.org/10.1152/ajpheart.00564.2020DOI Listing
January 2021

Therapeutic angiogenesis using autologous adipose-derived regenerative cells in patients with critical limb ischaemia in Japan: a clinical pilot study.

Sci Rep 2020 09 29;10(1):16045. Epub 2020 Sep 29.

Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.

Adipose-derived regenerative cell (ADRC) is a promising alternative source of autologous somatic stem cells for the repair of damaged tissue. This study aimed to assess the safety and feasibility of autologous ADRC implantation for therapeutic angiogenesis in patients with critical limb ischaemia (CLI). A clinical pilot study-Therapeutic Angiogenesis by Cell Transplantation using ADRCs (TACT-ADRC) study-was initiated in Japan. Adipose tissue was obtained by ordinary liposuction method. Isolated ADRCs were injected into the ischaemic limb. We performed TACT-ADRC procedure in five patients with CLI. At 6 months, no adverse events related to the TACT-ADRC were observed. No patients required major limb amputation, and ischaemic ulcers were partly or completely healed during the 6-month follow-up. In all cases, significant clinical improvements were seen in terms of rest pain and 6-min walking distance. Numbers of circulating CD34 and CD133 cells markers of progenitor cell persistently increased after ADRC implantation. The ratio of VEGF-Ab (an anti-angiogenic isoform of VEGF) to total VEGF-A in plasma significantly decreased after ADRC implantation. In vitro experiments, cultured with ADRC-conditioned media (CM) resulted in increased total VEGF-A and decreased VEGF-Ab in C2C12 cells, but not in macrophages. ADRC-CM also increased CD206 cells expression and decreased TNF-α in macrophages. Autologous ADRC implantation was safe and effective in patients with CLI and could repair damaged tissue via its ability to promote angiogenesis and suppress tissue inflammation.
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http://dx.doi.org/10.1038/s41598-020-73096-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7525513PMC
September 2020

Conditional Survival and Time of Biochemical Recurrence of Localized Prostate Cancer in Japanese Patients Undergoing Laparoscopic Radical Prostatectomies.

Ann Surg Oncol 2021 Feb 10;28(2):1247-1253. Epub 2020 Jul 10.

Department of Urology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa, 259-1193, Japan.

Purpose: Using conditional survival (CS) analysis, we investigated whether the duration of survival without biochemical recurrence (BCR) of prostate cancer after laparoscopic radical prostatectomies (LRP) affected the BCR rate. We also investigated the impact of well-known risk factors for BCR.

Methods: Between 2002 and 2014, 627 consecutive patients underwent LRPs at our institution. Prostate-specific antigen (PSA) concentrations above 0.2  ng/mL were defined as BCR. Conditional BCR-free survival rates were determined through Kaplan-Meier analysis. Assessment of potential BCR risk factors was performed using a Cox proportional hazard analysis.

Results: The 10-year BCR-free rates after LRP increased to 82.4%, 84.5%, 86.6%, 90.1%, and 94.7% in patients surviving 1, 2, 3, 5, and 7.5 years without BCR, respectively. Multivariate analyses of age, PSA concentrations, neoadjuvant therapy, and pathological findings were performed for all patients. In all patients, positive surgical margins (PSM) and Gleason Grade Groups (GG) ≥ 4 were independent risk factors for BCR (p < 0.001, hazard ratio [HR] = 2.45; and p < 0.001, HR = 2.83, respectively,). Similarly, PSM and GG ≥ 4 were significant risk factors in patients surviving 1-5 years without BCR. No clear risk factors were observed in patients surviving > 5 years without BCR after LRPs.

Conclusions: The BCR-free rate increased with time after LRP. It is recommended that patients with PSM, GG ≥ 4, or with both factors are strictly monitored for 5 years postoperatively. CS analysis is particularly useful for predicting the postoperative course of patients.
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http://dx.doi.org/10.1245/s10434-020-08770-6DOI Listing
February 2021

Role of DJ-1 in Modulating Glycative Stress in Heart Failure.

J Am Heart Assoc 2020 02 13;9(4):e014691. Epub 2020 Feb 13.

Division of Cardiothoracic Surgery Department of Surgery Carlyle Fraser Heart Center Emory University School of Medicine Atlanta GA.

Background DJ-1 is a ubiquitously expressed protein typically associated with the development of early onset Parkinson disease. Recent data suggest that it also plays a role in the cellular response to stress. Here, we sought to determine the role DJ-1 plays in the development of heart failure. Methods and Results Initial studies found that DJ-1 deficient mice (DJ-1 knockout; male; 8-10 weeks of age) exhibited more severe left ventricular cavity dilatation, cardiac dysfunction, hypertrophy, and fibrosis in the setting of ischemia-reperfusion-induced heart failure when compared with wild-type littermates. In contrast, the overexpression of the active form of DJ-1 using a viral vector approach resulted in significant improvements in the severity of heart failure when compared with mice treated with a control virus. Subsequent studies aimed at evaluating the underlying protective mechanisms found that cardiac DJ-1 reduces the accumulation of advanced glycation end products and activation of the receptor for advanced glycation end products-thus, reducing glycative stress. Conclusions These results indicate that DJ-1 is an endogenous cytoprotective protein that protects against the development of ischemia-reperfusion-induced heart failure by reducing glycative stress. Our findings also demonstrate the feasibility of using a gene therapy approach to deliver the active form of DJ-1 to the heart as a therapeutic strategy to protect against the consequences of ischemic injury, which is a major cause of death in western populations.
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http://dx.doi.org/10.1161/JAHA.119.014691DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7070196PMC
February 2020

Protein Kinase N Promotes Stress-Induced Cardiac Dysfunction Through Phosphorylation of Myocardin-Related Transcription Factor A and Disruption of Its Interaction With Actin.

Circulation 2019 11 30;140(21):1737-1752. Epub 2019 Sep 30.

Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan.

Background: Heart failure is a complex syndrome that results from structural or functional impairment of ventricular filling or blood ejection. Protein phosphorylation is a major and essential intracellular mechanism that mediates various cellular processes in cardiomyocytes in response to extracellular and intracellular signals. The RHOA-associated protein kinase (ROCK/Rho-kinase), an effector regulated by the small GTPase RHOA, causes pathological phosphorylation of proteins, resulting in cardiovascular diseases. RHOA also activates protein kinase N (PKN); however, the role of PKN in cardiovascular diseases remains unclear.

Methods: To explore the role of PKNs in heart failure, we generated tamoxifen-inducible, cardiomyocyte-specific PKN1- and PKN2-knockout mice by intercrossing the αMHC-CreERT2 line with and mice and applied a mouse model of transverse aortic constriction- and angiotensin II-induced heart failure. To identify a novel substrate of PKNs, we incubated GST-tagged myocardin-related transcription factor A (MRTFA) with recombinant GST-PKN-catalytic domain or GST-ROCK-catalytic domain in the presence of radiolabeled ATP and detected radioactive GST-MRTFA as phosphorylated MRTFA.

Results: We demonstrated that RHOA activates 2 members of the PKN family of proteins, PKN1 and PKN2, in cardiomyocytes of mice with cardiac dysfunction. Cardiomyocyte-specific deletion of the genes encoding and (cmc-PKN1/2 DKO) did not affect basal heart function but protected mice from pressure overload- and angiotensin II-induced cardiac dysfunction. Furthermore, we identified MRTFA as a novel substrate of PKN1 and PKN2 and found that MRTFA phosphorylation by PKN was considerably more effective than that by ROCK in vitro. We confirmed that endogenous MRTFA phosphorylation in the heart was induced by pressure overload- and angiotensin II-induced cardiac dysfunction in wild-type mice, whereas cmc-PKN1/2 DKO mice suppressed transverse aortic constriction- and angiotensin II-induced phosphorylation of MRTFA. Although RHOA-mediated actin polymerization accelerated MRTFA-induced gene transcription, PKN1 and PKN2 inhibited the interaction of MRTFA with globular actin by phosphorylating MRTFA, causing increased serum response factor-mediated expression of cardiac hypertrophy- and fibrosis-associated genes.

Conclusions: Our results indicate that PKN1 and PKN2 activation causes cardiac dysfunction and is involved in the transition to heart failure, thus providing unique targets for therapeutic intervention for heart failure.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.119.041019DOI Listing
November 2019

Cardiomyocytes capture stem cell-derived, anti-apoptotic microRNA-214 via clathrin-mediated endocytosis in acute myocardial infarction.

J Biol Chem 2019 08 19;294(31):11665-11674. Epub 2019 Jun 19.

Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan, 65 Tsurumai, Showa, Nagoya 466-8550, Japan

Extracellular vesicles (EVs) have emerged as key mediators of intercellular communication that have the potential to improve cardiac function when used in cell-based therapy. However, the means by which cardiomyocytes respond to EVs remains unclear. Here, we sought to clarify the role of exosomes in improving cardiac function by investigating the effect of cardiomyocyte endocytosis of exosomes from mesenchymal stem cells on acute myocardial infarction (MI). Exposing cardiomyocytes to the culture supernatant of adipose-derived regenerative cells (ADRCs) prevented cardiomyocyte cell damage under hypoxia , the injection of ADRCs into the heart simultaneous with coronary artery ligation decreased overall cardiac infarct area and prevented cardiac rupture after acute MI. Quantitative RT-PCR-based analysis of the expression of 35 known anti-apoptotic and secreted microRNAs (miRNAs) in ADRCs revealed that ADRCs express several of these miRNAs, among which miR-214 was the most abundant. Of note, miR-214 silencing in ADRCs significantly impaired the anti-apoptotic effects of the ADRC treatment on cardiomyocytes and To examine cardiomyocyte endocytosis of exosomes, we cultured the cardiomyocytes with ADRC-derived exosomes labeled with the fluorescent dye PKH67 and found that hypoxic culture conditions increased the levels of the labeled exosomes in cardiomyocytes. Chlorpromazine, an inhibitor of clathrin-mediated endocytosis, significantly suppressed the ADRC-induced decrease of hypoxia-damaged cardiomyocytes and also decreased hypoxia-induced cardiomyocyte capture of both labeled EVs and extracellular miR-214 secreted from ADRCs. Our results indicate that clathrin-mediated endocytosis in cardiomyocytes plays a critical role in their uptake of circulating, exosome-associated miRNAs that inhibit apoptosis.
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http://dx.doi.org/10.1074/jbc.RA119.007537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6682734PMC
August 2019

Impact of Lymphangiogenesis on Cardiac Remodeling After Ischemia and Reperfusion Injury.

J Am Heart Assoc 2018 10;7(19):e009565

1 Division of Cardiothoracic Surgery Department of Surgery Carlyle Fraser Heart Center Emory University School of Medicine Atlanta GA.

Background Lymphatic vessels interconnect with blood vessels to form an elaborate system that aids in the control of tissue pressure and edema formation. Although the lymphatic system has been known to exist in a heart, little is known about the role the cardiac lymphatic system plays in the development of heart failure. Methods and Results Mice (C57 BL /6J, male, 8 to 12 weeks of age) were subjected to either myocardial ischemia or myocardial ischemia and reperfusion for up to 28 days. Analysis revealed that both models increased the protein expression of vascular endothelial growth factor C and VEGF receptor 3 starting at 1 day after the onset of injury, whereas a significant increase in lymphatic vessel density was observed starting at 3 days. Further studies aimed to determine the consequences of inhibiting the endogenous lymphangiogenesis response on the development of heart failure. Using 2 different pharmacological approaches, we found that inhibiting VEGF receptor 3 with MAZ -51 and blocking endogenous vascular endothelial growth factor C with a neutralizing antibody blunted the increase in lymphatic vessel density, blunted lymphatic transport, increased inflammation, increased edema, and increased cardiac dysfunction. Subsequent studies revealed that augmentation of the endogenous lymphangiogenesis response with vascular endothelial growth factor C treatment reduced inflammation, reduced edema, and improved cardiac dysfunction. Conclusions These results suggest that the endogenous lymphangiogenesis response plays an adaptive role in the development of ischemic-induced heart failure and supports the emerging concept that therapeutic lymphangiogenesis is a promising new approach for the treatment of cardiovascular disease.
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http://dx.doi.org/10.1161/JAHA.118.009565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6404883PMC
October 2018

Hydrogen sulfide regulates cardiac mitochondrial biogenesis via the activation of AMPK.

J Mol Cell Cardiol 2018 03 3;116:29-40. Epub 2018 Feb 3.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, GA, USA. Electronic address:

Background: Hydrogen sulfide (HS) is an important regulator of mitochondrial bioenergetics, but its role in regulating mitochondrial biogenesis is not well understood. Using both genetic and pharmacological approaches, we sought to determine if HS levels directly influenced cardiac mitochondrial content.

Results: Mice deficient in the HS-producing enzyme, cystathionine γ-lyase (CSE KO) displayed diminished cardiac mitochondrial content when compared to wild-type hearts. In contrast, mice overexpressing CSE (CSE Tg) and mice supplemented with the orally active HS-releasing prodrug, SG-1002, displayed enhanced cardiac mitochondrial content. Additional analysis revealed that cardiac HS levels influenced the nuclear localization and transcriptional activity of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) with higher levels having a positive influence and lower levels having a negative influence. Studies aimed at evaluating the underlying mechanisms found that HS required AMP-activated protein kinase (AMPK) to induce PGC1α signaling and mitochondrial biogenesis. Finally, we found that restoring HS levels with SG-1002 in the setting of heart failure increased cardiac mitochondrial content, improved mitochondrial respiration, improved ATP production efficiency, and improved cardiac function.

Conclusions: Together, these results suggest that hydrogen sulfide is an important regulator of cardiac mitochondrial content and establishes that exogenous hydrogen sulfide can induce mitochondrial biogenesis via an AMPK-PGC1α signaling cascade.
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http://dx.doi.org/10.1016/j.yjmcc.2018.01.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5845802PMC
March 2018

Gut microbial metabolite short-chain fatty acids and obesity.

Biosci Microbiota Food Health 2017 25;36(4):135-140. Epub 2017 Aug 25.

Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo 183-8509, Japan.

Over the past decade, the gut microbiota has emerged as an essential mediator in the pathophysiology of obesity and related metabolic disorders. In this context, the reciprocal interactions of the gut microbiota structure and their metabolite profiles with host metabolism predisposing to a range of pathological conditions (e.g., insulin resistance) related to energy homeostasis have been increasingly discussed in various animal models and human cohorts. Remarkably, as the role of gut microbial metabolites as critical signaling molecules that function through the complementary host receptors has come to be appreciated, tremendous attention has been focused on the proposed diet-gut microbiota-host homeostasis axis, entailing extensive cross-disciplinary efforts in medical, pharmaceutical, and agricultural sciences. This review will discuss the recent advances in understanding the mechanisms whereby the gut microbiota modulates the effects of diet and shapes the host metabolism either towards or away from obesity and related metabolic conditions. In particular, the interactions of short chain fatty acids (SCFAs), a subset of key gut microbial metabolites, with their specific receptors will be reviewed in relation to host energy homeostatic regulation and evaluated for potential as novel therapeutic targets for diet-induced obesity.
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http://dx.doi.org/10.12938/bmfh.17-010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5633527PMC
August 2017

Exercise training provides cardioprotection by activating and coupling endothelial nitric oxide synthase a β-adrenergic receptor-AMP-activated protein kinase signaling pathway.

Med Gas Res 2017 Jan-Mar;7(1):1-8. Epub 2017 Mar 30.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, GA, USA.

Exercise training confers sustainable protection against ischemia/reperfusion injury. However, the mechanism by which this process occurs is not fully understood. Previously, it was shown that β-adrenergic receptors (β-ARs) play a critical role in regulating the activation of endothelial nitric oxide synthase (eNOS) in response to exercise and play a critical role in exercise-mediated cardioprotection. Intriguingly, a deficiency in β-ARs led to increased myocardial injury following exercise training. The purpose of the current study was to determine mechanisms by which β-ARs are linked to eNOS activation and to determine the mechanism responsible for the exacerbated ischemia/reperfusion injury displayed by β-AR deficient (β-AR KO) mice after exercise training. Wild-type ( = 37) and β-AR KO ( = 40) mice were subjected to voluntary wheel running for 4 weeks. Western blot analysis revealed that neither protein kinase B nor protein kinase A linked β-ARs to eNOS following exercise training. However, analysis revealed a role for AMP-activated protein kinase (AMPK). Specifically, exercise training increased the phosphorylation of AMPK in the hearts of wild-type mice, but failed to do so in the hearts of β-AR KO mice. Additional studies revealed that exercise training rendered eNOS less coupled and increased NOS-dependent superoxide levels in β-AR KO mice. Finally, supplementing β-AR KO mice with the eNOS coupler, tetrahydrobiopterin, during the final week of exercise training reduced myocardial infarction. These findings provide important information that exercise training protects the heart in the setting of myocardial ischemia/reperfusion injury by activating and coupling eNOS the stimulation of a β-AR-AMPK signaling pathway.
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http://dx.doi.org/10.4103/2045-9912.202904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5402342PMC
March 2017

Diallyl Trisulfide Augments Ischemia-Induced Angiogenesis via an Endothelial Nitric Oxide Synthase-Dependent Mechanism.

Circ J 2017 May 17;81(6):870-878. Epub 2017 Feb 17.

Department of Cardiology, Nagoya University Graduate School of Medicine.

Background: Hydrogen sulfide (HS) exerts beneficial actions against the development of cardiovascular disease. Diallyl trisulfide (DATS) is an organic polysulfide found in garlic oil that liberates HS under physiological conditions. This study investigated whether DATS modulates endothelial cell function, as well as revascularization processes in a mouse model of hind-limb ischemia.Methods and Results:Wild-type (WT), endothelial nitric oxide synthase-deficient (eNOS-KO) and Akt1-heterogenic deficient (Akt-Het) mice were subjected to unilateral hindlimb ischemia (HLI). DATS or a vehicle control was injected into the abdomen of mice for up to 10 days following HLI induction. Treatment with DATS enhanced blood flow recovery and capillary density in the ischemic limbs of WT mice. This was accompanied by a reduction in apoptotic activity and oxidative stress in the ischemic muscles. DATS also increased the phosphorylation of Akt and eNOS in ischemic muscles. In contrast to WT mice, DATS did not improve blood flow of eNOS-KO and Akt-Het mice. In cultured human umbilical vein endothelium cells, DATS decreased apoptotic activity and oxidative stress under hypoxic conditions, and stimulated the phosphorylation of Akt and eNOS. Inhibition of Akt or NOS signaling reversed DATS-stimulated eNOS phosphorylation and blocked the effects of DATS on apoptosis and oxidative stress.

Conclusions: These observations suggest that DATS promotes revascularization in response to HLI through its ability to stimulate the Akt-eNOS signaling pathway.
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http://dx.doi.org/10.1253/circj.CJ-16-1097DOI Listing
May 2017

Point vortex interactions on a toroidal surface.

Proc Math Phys Eng Sci 2016 Jul;472(2191):20160271

Department of Mathematics , Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.

Owing to non-constant curvature and a handle structure, it is not easy to imagine intuitively how flows with vortex structures evolve on a toroidal surface compared with those in a plane, on a sphere and a flat torus. In order to cultivate an insight into vortex interactions on this manifold, we derive the evolution equation for -point vortices from Green's function associated with the Laplace-Beltrami operator there, and we then formulate it as a Hamiltonian dynamical system with the help of the symplectic geometry and the uniformization theorem. Based on this Hamiltonian formulation, we show that the 2-vortex problem is integrable. We also investigate the point vortex equilibria and the motion of two-point vortices with the strengths of the same magnitude as one of the fundamental vortex interactions. As a result, we find some characteristic interactions between point vortices on the torus. In particular, two identical point vortices can be locally repulsive under a certain circumstance.
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http://dx.doi.org/10.1098/rspa.2016.0271DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4971253PMC
July 2016

Recycling KATP channels for cardioprotection.

Am J Physiol Heart Circ Physiol 2016 06 3;310(11):H1381-2. Epub 2016 May 3.

Carlyle Fraser Heart Center of Emory University Hospital Midtown, Atlanta, Georgia; and Division of Cardiothoracic Surgery, Department of Surgery, Emory University School of Medicine, Atlanta Georgia

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http://dx.doi.org/10.1152/ajpheart.00309.2016DOI Listing
June 2016

DJ-1 protects the heart against ischemia-reperfusion injury by regulating mitochondrial fission.

J Mol Cell Cardiol 2016 08 22;97:56-66. Epub 2016 Apr 22.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, GA, USA. Electronic address:

Recent data indicates that DJ-1 plays a role in the cellular response to stress. Here, we aimed to examine the underlying molecular mechanisms mediating the actions of DJ-1 in the heart following myocardial ischemia-reperfusion (I/R) injury. In response to I/R injury, DJ-1 KO mice displayed increased areas of infarction and worsened left ventricular function when compared to WT mice, confirming a protective role for DJ-1 in the heart. In an effort to evaluate the potential mechanism(s) responsible for the increased injury in DJ-1 KO mice, we focused on SUMOylation, a post-translational modification process that regulates various aspects of protein function. DJ-1 KO hearts after I/R injury were found to display enhanced accumulation of SUMO-1 modified proteins and reduced SUMO-2/3 modified proteins. Further analysis, revealed that the protein expression of the de-SUMOylation enzyme SENP1 was reduced, whereas the expression of SENP5 was enhanced in DJ-1 KO hearts after I/R injury. Finally, DJ-1 KO hearts were found to display enhanced SUMO-1 modification of dynamin-related protein 1, excessive mitochondrial fission, and dysfunctional mitochondria. Our data demonstrates that the activation of DJ-1 in response to myocardial I/R injury protects the heart by regulating the SUMOylation status of Drp1 and attenuating excessive mitochondrial fission.
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http://dx.doi.org/10.1016/j.yjmcc.2016.04.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5002379PMC
August 2016

Sodium Sulfide Attenuates Ischemic-Induced Heart Failure by Enhancing Proteasomal Function in an Nrf2-Dependent Manner.

Circ Heart Fail 2016 Apr;9(4):e002368

From the Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center (Y.S., C.K.N., J.P.L., L.A.B., N.K., D.H., J.W.C.), Department of Medicine, Division of Cardiology (L.T., A.H., N.N.), and Department of Pediatrics (J.M.H.), Emory University School of Medicine, Atlanta, GA; and Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.).

Background: Therapeutic strategies aimed at increasing hydrogen sulfide (H2S) levels exert cytoprotective effects in various models of cardiovascular injury. However, the underlying mechanism(s) responsible for this protection remain to be fully elucidated. Nuclear factor E2-related factor 2 (Nrf2) is a cellular target of H2S and facilitator of H2S-mediated cardioprotection after acute myocardial infarction. Here, we tested the hypothesis that Nrf2 mediates the cardioprotective effects of H2S therapy in the setting of heart failure.

Methods And Results: Mice (12 weeks of age) deficient in Nrf2 (Nrf2 KO; C57BL/6J background) and wild-type littermates were subjected to ischemic-induced heart failure. Wild-type mice treated with H2S in the form of sodium sulfide (Na2S) displayed enhanced Nrf2 signaling, improved left ventricular function, and less cardiac hypertrophy after the induction of heart failure. In contrast, Na2S therapy failed to provide protection against heart failure in Nrf2 KO mice. Studies aimed at evaluating the underlying cardioprotective mechanisms found that Na2S increased the expression of proteasome subunits, resulting in an increased proteasome activity and a reduction in the accumulation of damaged proteins. In contrast, Na2S therapy failed to enhance the proteasome and failed to attenuate the accumulation of damaged proteins in Nrf2 KO mice. Additionally, Na2S failed to improve cardiac function when the proteasome was inhibited.

Conclusions: These findings indicate that Na2S therapy enhances proteasomal activity and function during the development of heart failure in an Nrf2-dependent manner and that this enhancement leads to attenuation in cardiac dysfunction.
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http://dx.doi.org/10.1161/CIRCHEARTFAILURE.115.002368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4826721PMC
April 2016

Adipose-Derived Regenerative Cells for Cardiovascular Regeneration--A Novel Therapy for the Cardiac Conduction System.

Circ J 2015 5;79(12):2555-6. Epub 2015 Nov 5.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine.

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http://dx.doi.org/10.1253/circj.CJ-15-1106DOI Listing
August 2016

Effects of Defecation Strain at Various Bed Reclining Angles on Intrarectal Pressure and Cardiovascular Responses.

Nurs Res 2015 Nov-Dec;64(6):413-21

Mika Imai, RN, MS, is Assistant Professor, Department of Nursing, Ogaki Women's College, and Department of Nursing, Nagoya University School of Health Sciences, Japan. Yuko Kuwahara, DVM, PhD, is Research Associate, Department of Physiology, Aichi Medical University, Nagakute, Japan. Makoto Hirai, MD, PhD, is Professor, Department of Nursing, Nagoya University School of Health Sciences, Japan. Rumiko Nishimura, MS, is PhD Candidate; Naoki Nishimura, PhD, is Assistant Professor; and Yuuki Shimizu, PhD, is Assistant Professor, Department of Physiology, Aichi Medical University, Nagakute, Japan. Tetsuya Fujii, RN, PhD, is Professor, Department of Nursing, Seirei Christopher University, Hamamatsu, Japan. Satoshi Iwase, MD, PhD, is Professor, Department of Physiology, Aichi Medical University, Nagakute, Japan.

Background: There is no clear information about the optimal bed reclining angle for promoting efficient and safe defecation in bedfast patients.

Objective: The aim of this study was to examine the optimal bed reclining angle for facilitating increases in intrarectal pressure without causing marked cardiovascular changes in order to develop an efficient and safe defecation position for bedfast patients.

Methods: Twelve healthy men participated in this study. The subjects were required to strain for 15 seconds at the end stage of inspiration while their bed was reclined at 0° (supine), 15°, 30°, or 60°. During straining, the subjects were asked to maintain (a) an intrarectal pressure of 20 mm Hg or (b) the maximal intrarectal pressure. Intrarectal pressure, blood pressure, heart rate, and abdominal muscle activity (electromyographic activity) were recorded continuously throughout the study period.

Results: During straining, intrarectal pressure increased with the reclining angle, and a significant linear correlation was detected between the sine of the reclining angle of the bed and intrarectal pressure (η = .57, p < .01). When subjects were straining with the aim of maintaining maximal intrarectal pressure, the extent of the observed changes (delta) in blood pressure and heart rate did not differ significantly across the reclining angles. When subjects were straining with the aim of maintaining an intrarectal pressure of 20 mm Hg, the delta blood pressure decreased as the reclining angle increased 0°: M = 23.7, SD = 15.3 mm Hg, 95% CI [11.9, 35.4]; 15°: M = 25.9, SD = 10.8 mm Hg, 95% CI [17.6, 34.2]; 30°: M = 17.7, SD = 9.4 mm Hg, 95% CI [10.4, 24.9]; 60°: M = 15.5, SD = 9.5 mm Hg, 95% CI [8.1, 22.8]; 15° versus 30°: p < .05; 15° versus 60°: p < .05. The amount of muscle activity observed during straining decreased as the reclining angle increased.

Discussion: In bedfast patients, it is suggested that higher reclining angles may enable safer and more efficient defecation, because it decreases the amount of muscle activity required to increase the intrarectal pressure and reduces the potentially deleterious effects of straining on the cardiovascular system to develop an efficient and safe defecation position for bedfast patients.
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http://dx.doi.org/10.1097/NNR.0000000000000118DOI Listing
February 2016

Hydrogen sulfide attenuates high fat diet-induced cardiac dysfunction via the suppression of endoplasmic reticulum stress.

Nitric Oxide 2015 Apr 6;46:145-56. Epub 2015 Jan 6.

Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, GA, USA. Electronic address:

Diabetic cardiomyopathy is a significant contributor to the morbidity and mortality associated with diabetes and metabolic syndrome. However, the underlying molecular mechanisms that lead to its development have not been fully elucidated. Hydrogen sulfide (H2S) is an endogenously produced signaling molecule that is critical for the regulation of cardiovascular homeostasis. Recently, therapeutic strategies aimed at increasing its levels have proven cardioprotective in models of acute myocardial ischemia-reperfusion injury and heart failure. The precise role of H2S in the pathogenesis of diabetic cardiomyopathy has not yet been established. Therefore, the goal of the present study was to evaluate circulating and cardiac H2S levels in a murine model of high fat diet (HFD)-induced cardiomyopathy. Diabetic cardiomyopathy was produced by feeding mice HFD (60% fat) chow for 24 weeks. HFD feeding reduced both circulating and cardiac H2S and induced hallmark features of type-2 diabetes. We also observed marked cardiac dysfunction, evidence of cardiac enlargement, cardiac hypertrophy, and fibrosis. H2S therapy (SG-1002, an orally active H2S donor) restored sulfide levels, improved some of the metabolic perturbations stemming from HFD feeding, and attenuated HFD-induced cardiac dysfunction. Additional analysis revealed that H2S therapy restored adiponectin levels and suppressed cardiac ER stress stemming from HFD feeding. These results suggest that diminished circulating and cardiac H2S levels play a role in the pathophysiology of HFD-induced cardiomyopathy. Additionally, these results suggest that H2S therapy may be of clinical importance in the treatment of cardiovascular complications stemming from diabetes.
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http://dx.doi.org/10.1016/j.niox.2014.12.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4361249PMC
April 2015

Arousal electrical stimuli evoke sudomotor activity related to P300, and skin vasoconstrictor activity related to N140 in humans.

Clin Neurophysiol 2015 May 15;126(5):933-42. Epub 2014 Sep 15.

Department of Physiology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.

Objective: Arousal stimuli evoke bursts of skin sympathetic nerve activity (SSNA). SSNA usually contains sudomotor and vasoconstrictor neural spikes. The aim of this study was to elucidate which components of event-related potentials (ERPs) are related to sudomotor and vasoconstrictor responses comprising arousal SSNA bursts.

Methods: We recorded SSNA from the tibial nerve by microneurography, with corresponding sympathetic skin response (SSR), sympathetic flow response (SFR), and ERPs in 10 healthy subjects. Electrical stimulation of the median nerve was used to induce arousal responses. ERPs were classified by the occurrence of SSR and SFR.

Results: SSNA bursts followed by SSR were associated with larger P300 than SSNA bursts followed by no SSR. For N140, no difference in the amplitude was found between SSNA bursts with and without SSR. SSNA bursts followed by SFR were associated with larger N140 than SSNA bursts followed by no SFR. However, there were no differences in the amplitude of P300 between SSNA bursts with and without SFR.

Conclusions: Sudomotor and skin vasoconstrictor responses to arousal stimuli were differently associated with distinct ERP components.

Significance: The possibility that sudomotor and skin vasoconstrictor activities comprising arousal SSNA reflect different stages of the cognitive process is suggested.
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http://dx.doi.org/10.1016/j.clinph.2014.08.018DOI Listing
May 2015

Characterisation of the LH2 spectral variants produced by the photosynthetic purple sulphur bacterium Allochromatium vinosum.

Biochim Biophys Acta 2014 Nov 8;1837(11):1849-1860. Epub 2014 Aug 8.

Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, UK.

This study systematically investigated the different types of LH2 produced by Allochromatium (Alc.) vinosum, a photosynthetic purple sulphur bacterium, in response to variations in growth conditions. Three different spectral forms of LH2 were isolated and purified, the B800-820, B800-840 and B800-850 LH2 types, all of which exhibit an unusual split 800 peak in their low temperature absorption spectra. However, it is likely that more forms are also present. Relatively more B800-820 and B800-840 are produced under low light conditions, while relatively more B800-850 is produced under high light conditions. Polypeptide compositions of the three different LH2 types were determined by a combination of HPLC and TOF/MS. The B800-820, B800-840 and B800-850 LH2 types all have a heterogeneous polypeptide composition, containing multiple types of both α and β polypeptides, and differ in their precise polypeptide composition. They all have a mixed carotenoid composition, containing carotenoids of the spirilloxanthin series. In all cases the most abundant carotenoid is rhodopin; however, there is a shift towards carotenoids with a higher conjugation number in LH2 complexes produced under low light conditions. CD spectroscopy, together with the polypeptide analysis, demonstrates that these Alc. vinosum LH2 complexes are more closely related to the LH2 complex from Phs. molischianum than they are to the LH2 complexes from Rps. acidophila.
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http://dx.doi.org/10.1016/j.bbabio.2014.07.022DOI Listing
November 2014

Vildagliptin stimulates endothelial cell network formation and ischemia-induced revascularization via an endothelial nitric-oxide synthase-dependent mechanism.

J Biol Chem 2014 Sep 6;289(39):27235-27245. Epub 2014 Aug 6.

Department of Cardiology, Nagoya University Graduate School of Medicine, 466-8550 Nagoya, Japan,. Electronic address:

Dipeptidyl peptidase-4 inhibitors are known to lower glucose levels and are also beneficial in the management of cardiovascular disease. Here, we investigated whether a dipeptidyl peptidase-4 inhibitor, vildagliptin, modulates endothelial cell network formation and revascularization processes in vitro and in vivo. Treatment with vildagliptin enhanced blood flow recovery and capillary density in the ischemic limbs of wild-type mice, with accompanying increases in phosphorylation of Akt and endothelial nitric-oxide synthase (eNOS). In contrast to wild-type mice, treatment with vildagliptin did not improve blood flow in ischemic muscles of eNOS-deficient mice. Treatment with vildagliptin increased the levels of glucagon-like peptide-1 (GLP-1) and adiponectin, which have protective effects on the vasculature. Both vildagliptin and GLP-1 increased the differentiation of cultured human umbilical vein endothelial cells (HUVECs) into vascular-like structures, although vildagliptin was less effective than GLP-1. GLP-1 and vildagliptin also stimulated the phosphorylation of Akt and eNOS in HUVECs. Pretreatment with a PI3 kinase or NOS inhibitor blocked the stimulatory effects of both vildagliptin and GLP-1 on HUVEC differentiation. Furthermore, treatment with vildagliptin only partially increased the limb flow of ischemic muscle in adiponectin-deficient mice in vivo. GLP-1, but not vildagliptin, significantly increased adiponectin expression in differentiated 3T3-L1 adipocytes in vitro. These data indicate that vildagliptin promotes endothelial cell function via eNOS signaling, an effect that may be mediated by both GLP-1-dependent and GLP-1-independent mechanisms. The beneficial activity of GLP-1 for revascularization may also be partially mediated by its ability to increase adiponectin production.
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http://dx.doi.org/10.1074/jbc.M114.557835DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175356PMC
September 2014

Cardiac myocyte-derived follistatin-like 1 prevents renal injury in a subtotal nephrectomy model.

J Am Soc Nephrol 2015 Mar 28;26(3):636-46. Epub 2014 Jul 28.

Molecular Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan;

Heart disease contributes to the progression of CKD. Heart tissue produces a number of secreted proteins, also known as cardiokines, which participate in intercellular and intertissue communication. We recently reported that follistatin-like 1 (Fstl1) functions as a cardiokine with cardioprotective properties. Here, we investigated the role of cardiac Fstl1 in renal injury after subtotal nephrectomy. Cardiac-specific Fstl1-deficient (cFstl1-KO) mice and wild-type mice were subjected to subtotal (5/6) nephrectomy. cFstl1-KO mice showed exacerbation of urinary albumin excretion, glomerular hypertrophy, and tubulointerstitial fibrosis after subtotal renal ablation compared with wild-type mice. cFstl1-KO mice also exhibited increased mRNA levels of proinflammatory cytokines, including TNF-α and IL-6, NADPH oxidase components, and fibrotic mediators, in the remnant kidney. Conversely, systemic administration of adenoviral vectors expressing Fstl1 (Ad-Fstl1) to wild-type mice with subtotal nephrectomy led to amelioration of albuminuria, glomerular hypertrophy, and tubulointerstitial fibrosis, accompanied by reduced expression of proinflammatory mediators, NADPH oxidase components, and fibrotic markers in the remnant kidney. In cultured human mesangial cells, treatment with recombinant FSTL1 attenuated TNF-α-stimulated expression of proinflammatory cytokines. Treatment of mesangial cells with FSTL1 augmented the phosphorylation of AMP-activated protein kinase (AMPK), and inhibition of AMPK activation abrogated the anti-inflammatory effects of FSTL1. These data suggest that Fstl1 functions in cardiorenal communication and that the lack of Fstl1 production by myocytes promotes glomerular and tubulointerstitial damage in the kidney.
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http://dx.doi.org/10.1681/ASN.2014020210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4341480PMC
March 2015

Therapeutic angiogenesis by autologous adipose-derived regenerative cells: comparison with bone marrow mononuclear cells.

Am J Physiol Heart Circ Physiol 2014 Sep 25;307(6):H869-79. Epub 2014 Jul 25.

Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.

Transplantation of adipose-derived regenerative cell (ADRC) enhances ischemia-induced angiogenesis, but the underlying mechanism remains unknown. Here, we compared the efficacy between ADRC and bone marrow mononuclear cell (BM-MNC) transplantation in rabbits model of hindlimb ischemia and examined the possible roles of alternative phenotypic macrophages polarization in ADRC-mediated angiogenesis using mice model of hindlimb ischemia. ADRCs and BM-MNCs were isolated from New Zealand White rabbits and C57BL/6J mice. In rabbit studies, our data showed that ADRCs could incorporate into the endothelial vasculature in vitro and in vivo. Both ADRC-conditioned media (CM) and BM-MNC-CM enhanced the migratory ability and interrupted the process of apoptosis in human umbilical vein endothelial cells. Four weeks after cell transplantation, augmentation of postnatal neovascularization was observed in the ischemic muscle injected with either ADRCs or BM-MNCs. In mice studies, we presented that ADRCs polarized into the IL-10-releasing M2 macrophages through PGE2-EP2/4 axis and suppressed the expressions of TNF-α and IL-6 in the ischemic muscle. Gene expressions of several angiogenic cytokines were amplified in the macrophages cultured in ADRC-CM rather than BM-MNC-CM. Blockade of IL-10 using neutralizing MAb attenuated the ADRC-mediated angiogenesis and caused muscle apoptosis in vivo. In conclusion, ADRC transplantation harvested similar effect of neovascularization augmentation compared with BM-MNC in experimental rabbit model of hindlimb ischemia; ADRC displayed a unique immunoregulatory manner of accelerating IL-10-releasing M2 macrophages polarization through the PGE2-EP2/4 axis.
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http://dx.doi.org/10.1152/ajpheart.00310.2014DOI Listing
September 2014
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