Current Perspectives of Mitochondria in Sepsis-Induced Cardiomyopathy.

Sepsis-induced cardiomyopathy (SICM) is one of the leading indicators for poor prognosis associated with sepsis. Despite its reversibility, prognosis varies widely among patients. Mitochondria play a key role in cellular energy production by generating adenosine triphosphate (ATP), which is vital for myocardial energy metabolism. Over recent years, mounting evidence suggests that severe sepsis not only triggers mitochondrial structural abnormalities such as apoptosis, incomplete autophagy, and mitophagy in cardiomyocytes but also compromises their function, leading to ATP depletion. This metabolic disruption is recognized as a significant contributor to SICM, yet effective treatment options remain elusive. Sepsis cannot be effectively treated with inotropic drugs in failing myocardium due to excessive inflammatory factors that blunt ß-adrenergic receptors. This review will share the recent knowledge on myocardial cell death in sepsis and its molecular mechanisms, focusing on the role of mitochondria as an important metabolic regulator of SICM, and discuss the potential for developing therapies for sepsis-induced myocardial injury.

A case of repeated Kounis syndrome after anaphylactic shock: A note for disease management.

Background: Kounis syndrome (KS) is an underdiagnosed disease. The management of the disease remains elusive because of its infrequency. Case Presentation: A 78-year-old man with anaphylactic shock was admitted to our hospital 2 h after multiple bee stings. After recovering from an anaphylactic reaction, he presented with chest pain with ST elevation. We diagnosed him with KS. After a continuous intravenous infusion of vasodilators, his chest pain and ST elevation improved. However, chest pain with ST-segment elevation recurred the next day. Coronary angiography revealed severe stenosis in the middle left anterior descending coronary artery, and drug-eluting stents were implanted. The patient was discharged on foot after treatment for heart failure. Conclusion: KS, in which anaphylaxis and acute coronary syndrome occur simultaneously, can recur repeatedly after an initial anaphylactic reaction; however, it could be delayed or it could present simultaneously with the anaphylactic reaction. Therefore, long-term observation is important.

A case of toxic epidermal necrolysis comorbid with severe burns.

Toxic epidermal necrolysis (TEN) and severe burns both have high mortality rates, but coexistence is extremely rare. The specificity of developing TEN in burn patients is not well understood and its treatment strategy is not established. Case Presentation: A 68-year-old man was carried to our hospital with severe burns covering 35% of his body surface area. He developed bacteremia during treatment of burns and required antimicrobial therapy. However, erythema appeared on the trunk and upper limbs and rapidly spread to the extremities, leading to a diagnosis of TEN. The rash gradually improved after terminating antimicrobial therapy and administrating of 1,000 mg/day methylprednisolone for 3 days. The rash caused by TEN was confined to non-burned areas, suggesting that TEN may less likely occur at burn sites. Conclusion: It is necessary to pay attention because burn patients can develop TEN concomitantly. Corticosteroids therapy may be effective for TEN even in severe burn patients.

A case of COVID-19-associated fulminant myocarditis successfully treated with mechanical circulatory support.

A 49-year-old man, who had not been vaccinated against COVID-19 visited the hospital for fever and cough, and a PCR test for COVID-19 was positive on the Day X. Initially, there was no decrease in oxygen saturation and the patient was under observation as a mild case without medication. Five days after the onset (Day X + 5), chest pain appeared. Electrocardiogram showed widespread ST-segment elevation, and blood tests showed high levels of troponin I. However, given that there was no stenotic lesion on coronary computed tomography, myocarditis was suspected, and he was transferred to our hospital on the Day X + 6. We started treatment with lemdesivir and dexamethasone. On the Day X + 7, the patient developed decreased left ventricular ejection fraction, hypotension, and hyperlactatemia. We decided that mechanical circulatory support was necessary and an Impella 5.0 was inserted under ventilator management. The patient was successfully weaned from the Impella 5.0 on the Day X + 17, was transferred to the general ward on the Day X + 24, continued rehabilitation, and was discharged home on the Day X + 39 with no heart failure symptoms. In this case, we performed daily bedside echocardiography and chose the Impella 5.0 instead of extra corporeal membrane oxygenation (ECMO) because there were no findings of severe pneumonia or right heart failure. The Impella 5.0 device was inserted via an axillary artery approach, given that it provides more assisted flow than the Impella CP inserted through the inguinal route. Furthermore, early rehabilitation was possible due to the lack of restriction of the lower body.

Efficacy and safety of tolvaptan in acute heart failure patients during long-distance transportation.

AIMS: Treating patients with acute heart failure is difficult at the local hospitals in medically depopulated areas where cardiologists are generally absent. These patients require long-distance and time-consuming transportation to the intensive care units. It is well known that tolvaptan is effective for the treatment of congestive heart failure, but the effect of prehospital tolvaptan use in patients is not well evaluated. The aim of this study was to evaluate the efficacy and safety of prehospital tolvaptan use in patients with acute congestive heart failure who require long-distance and time-consuming transportation. METHODS: This retrospective study included 30 patients who were newly diagnosed with acute heart failure at Wakkanai City Hospital and transported to Nayoro City General Hospital between January 2013 and May 2020. The patients were classified into those who received tolvaptan (tolvaptan group, n = 18) and did not receive tolvaptan (control group, n = 12). RESULTS: The percentage of patient survival at discharge did not show a statistically significant difference between the groups (100% [tolvaptan] vs. 91% [control], p = 0.414). During transportation, the percentage of patients in the tolvaptan group who required increased oxygen doses was statistically significantly lower than that in the control group (0% vs. 36%, p = 0.0181). Patients in the tolvaptan group had statistically significantly shorter intensive care unit stays (median: 2 days vs. 6 days, p = 0.0376), less days to discontinuation of oxygen (median: 2.8 days vs. 6.9 days, p < 0.00125), and less days to ambulation (median: 1.5 days vs. 7.5 days, p = 0.0362) compared with the control group. In the tolvaptan group, blood pressure was not different; however, heart rate was statistically significantly reduced (99 ± 21 vs. 88 ± 21 beats per minute, p = 0.016) during transportation. CONCLUSION: The use of tolvaptan in patients with acute heart failure requiring long-distance transport is safe and may show better clinical course compared with conventional therapies.

Cardiac Metabolism in Sepsis.

The mechanism of sepsis-induced cardiac dysfunction is believed to be different from that of myocardial ischemia. In sepsis, chemical mediators, such as endotoxins, cytokines, and nitric oxide, cause metabolic abnormalities, mitochondrial dysfunction, and downregulation of ß-adrenergic receptors. These factors inhibit the production of ATP, essential for myocardial energy metabolism, resulting in cardiac dysfunction. This review focuses on the metabolic changes in sepsis, particularly in the heart. In addition to managing inflammation, interventions focusing on metabolism may be a new therapeutic strategy for cardiac dysfunction due to sepsis.

ß3-Adrenergic receptor blockade reduces mortality in endotoxin-induced heart failure by suppressing induced nitric oxide synthase and saving cardiac metabolism.

The ß3-adrenergic receptor (ß3AR) is related to myocardial fatty acid metabolism and its expression has been implicated in heart failure. In this study, we investigated the role of ß3AR in sepsis-related myocardial dysfunction using lipopolysaccharide (LPS)-induced endotoxemia as a model of cardiac dysfunction. We placed mice into three treatment groups and treated each with intraperitoneal injections of the ß3AR agonist CL316243 (CL group), the ß3AR antagonist SR59230A (SR group), or normal saline (NS group). Survival rates were significantly improved in the SR group compared with the other treatment groups. Echocardiography analyses revealed cardiac dysfunction within 6-12 h of LPS injections, but the outcome was significantly better for the SR group. Myocardial ATP was preserved in the SR group but was decreased in the CL-treated mice. Additionally, quantitative PCR analysis revealed that expression levels of genes associated with fatty acid oxidation and glucose metabolism were significantly higher in the SR group. Furthermore, the expression levels of mitochondrial membrane protein complexes were preserved in the SR group. Electron microscope studies showed significant accumulation of lipid droplets in the CL group. Moreover, inducible nitric oxide synthase (iNOS) protein expression and nitric oxide were significantly reduced in the SR group. The in vitro study demonstrated that ß3AR has an independent iNOS pathway that does not go through the nuclear factor-κB pathway. These results suggest that blockading ß3AR improves impaired energy metabolism in myocardial tissues by suppressing iNOS expression and recovers cardiac function in animals with endotoxin-induced heart failure.NEW & NOTEWORTHY Nitric oxide production through stimulation of ß3-adrenergic receptor (ß3AR) may improve cardiac function in cases of chronic heart failure. We demonstrated that the blockade of ß3AR improved mortality and cardiac function in endotoxin-induced heart failure. We also determined that LPS-induced inducible nitric oxide synthase has a pathway that is independent of nuclear factor-κB, which worsened cardiac metabolism and mortality in the acute phase of sepsis. Treatment with the ß3AR antagonist had a favorable effect. Thus, the blockade of ß3AR could offer a novel treatment for sepsis-related heart failure.

Cerebral Microbleeds Remain for Nine Years: A Prospective Study with Yearly Magnetic Resonance Imaging.

BACKGROUND: Cerebral microbleeds (CMBs) are refined neuroimaging findings detected on T2*-weighted gradient echo (GRE) magnetic resonance imaging (MRI) and are widely accepted as an important marker of the vulnerability of cerebral small vessels. It is necessary to further clarify the natural history of CMBs by a longitudinal study. This study aimed to reveal the natural history of CMBs and find a better way to track CMBs by a prospective long-term observation. METHODS: We performed yearly brain MRI assessments for 7 or more years in 8 nonvalvular atrial fibrillation Japanese outpatients with CMBs detected in the baseline MRI. We began to use a 3.0T MRI scanner from 2012 as well. RESULTS: We followed up 3 patients for 9 years, 2 for 8 years, and 3 for 7 years. In all patients, the CMBs at baseline did not disappear during the follow-up period. Importantly, the CMB in 1 patient seemed to disappear during the sixth imaging using 1.5T T2*-weighted GRE but was detected again during the seventh imaging with 3.0T susceptibility weighted imaging and ninth imaging with 3.0T T2* GRE. Moreover, in a patient implanted with a pacemaker, which is only applicable for 1.5T MRI at present, the CMB seemed to disappear and appeared once again with a 1.5T T2*-weighted GRE at a slice thickness of 2.5 mm instead of 5 mm. CONCLUSIONS: From this prospective study, we obtained 2 absolutely new findings that CMBs remained for as long as 9 years and a high-field or thin-slice MRI can detect concealed CMBs.

Attenuation of teratoma formation by p27 overexpression in induced pluripotent stem cells.

BACKGROUND: Pluripotent stem cells, such as embryonic stem cells or induced pluripotent stem cells, have a great potential for regenerative medicine. Induced pluripotent stem cells, in particular, are suitable for replacement of tissue by autologous transplantation. However, tumorigenicity is a major risk in clinical application of both embryonic stem cells and induced pluripotent stem cells. This study explores the possibility of manipulating the cell cycle for inhibition of tumorigenicity. METHODS: We genetically modified mouse induced pluripotent stem cells (miPSCs) to overexpress p27 tumor suppressor and examined their proliferation rate, gene expression, cardiac differentiation, tumorigenicity, and therapeutic potential in a mouse model of coronary artery ligation. RESULTS: Overexpression of p27 inhibited cell division of miPSCs, and that inhibition was dependent on the expression level of p27. p27 overexpressing miPSCs had pluripotency characteristics but lost stemness earlier than normal miPSCs during embryoid body and teratoma formation. These cellular characteristics led to none or smaller teratoma when the cells were injected into nude mice. Transplantation of both miPSCs and p27 overexpressing miPSCs into the infarcted mouse heart reduced the infarction size and improved left ventricular function. CONCLUSIONS: The overexpression of p27 attenuated tumorigenicity by reducing proliferation and earlier loss of stemness of miPSCs. The overexpression of p27 did not affect pluripotency and differentiation characteristics of miPSC. Therefore, regulation of the proliferation rate of miPSCs offers great therapeutic potential for repair of the injured myocardium.

Blockade of senescence-associated microRNA-195 in aged skeletal muscle cells facilitates reprogramming to produce induced pluripotent stem cells.

The low reprogramming efficiency in cells from elderly patients is a challenge that must be overcome. Recently, it has been reported that senescence-associated microRNA (miR)-195 targets Sirtuin 1 (SIRT1) to advance cellular senescence. Thus, we hypothesized that a blockade of miR-195 expression could improve reprogramming efficiency in old skeletal myoblasts (SkMs). We found that miR-195 expression was significantly higher in old SkMs (24 months) isolated from C57BL/6 mice as compared to young SkMs (2 months, 2.3-fold). Expression of SIRT1 and telomerase reverse transcriptase (TERT) was downregulated in old SkMs, and transduction of old SkMs with lentiviral miR-195 inhibitor significantly restored their expression. Furthermore, quantitative in situ hybridization analysis demonstrated significant telomere elongation in old SkMs transduced with anti-miR-195 (1.7-fold increase). It is important to note that blocking miR-195 expression markedly increased the reprogramming efficiency of old SkMs as compared to scramble (2.2-fold increase). Transduction of anti-miR-195 did not alter karyotype or pluripotency marker expression. Induced pluripotent stem cells (iPSCs) from old SkMs transduced with anti-miR-195 successfully formed embryoid bodies that spontaneously differentiated into three germ layers, indicating that deletion of miR-195 does not affect pluripotency in transformed SkMs. In conclusion, this study provided novel evidence that the blockade of age-induced miR-195 is a promising approach for efficient iPSC generation from aging donor subjects, which has the potential for autologous transplantation of iPSCs in elderly patients.

Abrogation of Age-Induced MicroRNA-195 Rejuvenates the Senescent Mesenchymal Stem Cells by Reactivating Telomerase.

Previously, we reported that a novel subpopulation of young mesenchymal stem cells (YMSCs) existed in old bone marrow, which possessed high antiaging properties as well as excellent efficacy for cardiac repair. MicroRNAs (miRNAs) have emerged as key regulators in post-transcriptional gene expression programs, and however, it is unknown whether miRNAs directly control stem cell senescence. Here we present the first evidence that miR-195 overexpressed in old MSCs (OMSCs) induces stem cell senescence deteriorating their regenerative ability by directly deactivating telomerase reverse transcriptase (Tert), and abrogation of miR-195 can reverse stem cell aging. MiRNAs profiling analysis in YMSCs and OMSCs by microarray showed that miR-140, miR-146a/b, and miR-195 were significantly upregulated in OMSCs, which led us to hypothesize that these are age-induced miRNAs involved in stem cell senescence. Of these miRNAs, we found miR-195 directly targeted 3'-untranslated region of Tert gene by computational target prediction analysis and luciferase assay, and knockdown of miR-195 significantly increased Tert expression in OMSCs. Strikingly, miR-195 inhibition significantly induced telomere relengthening in OMSCs along with reduced expression of senescence-associated ß-galactosidase. Moreover, silencing miR-195 in OMSCs by transfection of miR-195 inhibitor significantly restored antiaging factors expression including Tert and Sirt1 as well as phosphorylation of Akt and FOXO1. Notably, abrogation of miR-195 markedly restored proliferative abilities in OMSCs. Transplantation of OMSCs with knocked out miR-195 reduced infarction size and improved LV function. In conclusion, rejuvenation of aged stem cells by miR-195 inhibition would be a promising autologous therapeutic strategy for cardiac repair in the elderly patients.

Report of a case: Retroperitoneal mucinous cystadenocarcinoma with rapid progression.

INTRODUCTION: Retroperitoneal mucinous cystic neoplasms are uncommon, and little is known about the etiology of the disease. Malignant forms of these are extremely rare. Here, we report a case of primary retroperitoneal mucinous cystadenocarcinoma (PRMC), which demonstrated unexpectedly aggressive progression despite finding only a limited area of adenocarcinoma. PRESENTATION OF CASE: A 62-year-old woman with a complaint of abdominal discomfort was admitted to the hospital. Abdominal CT and MRI showed multiple large retroperitoneal cysts dislocating the right kidney nearly to the center of the abdomen. Transabdominal resection of the cysts was performed. Those cysts contained 1100ml of mucinous fluids in total. Cytological examination of those fluids revealed no malignant cells. The cyst wall was lined with mucinous epithelial cells, and contained some ovarian-type stroma. Also, there was a focal area of adenocarcinoma in the cyst wall, and the lesion was diagnosed as primary retroperitoneal mucinous cystadenocarcinoma. Eight months later, the patient developed lumbar bone metastasis. Chemotherapy with S-1, an oral fluoropyrimidine, and docetaxel had been begun immediately; however, the disease had rapidly spread in the retroperitoneum. Eventually, the patient died of the disease 15 months after surgery. DISCUSSION: Retroperitoneal mucinous cystic neoplasms are considered to be metaplasia of embryonal coelomic epithelium. Complete excision without rupture is essential. However, variance of biological aggressiveness might exist in PRMCs. CONCLUSION: Retroperitoneal mucinous cystadenocarcinoma is a rare tumor, and it is urgently necessary to elucidate the etiology of an effective therapy for the disease.

Laparoscopic resection of schwannoma of the ascending colon.

Schwannomas of the colon are rare and difficult to diagnose preoperatively. We report a case of schwannoma of the ascending colon that was resected laparoscopically. A 64-year-old woman was referred to our hospital by her local clinic for further evaluation and management of a submucosal tumor of the ascending colon. A definitive preoperative diagnosis could not be reached despite examinations. Gastrointestinal stromal tumor, leiomyoma and lymphoma were the differential diagnoses. We performed a laparoscopic right hemicolectomy with D2 lymph node dissection. Histological findings with hematoxylin-eosin staining revealed spindle-like tumor cells, and immunohistochemical analysis showed that the tumor was positive for S-100 but negative for c-kit, CD34, smooth muscle actin and desmin, with a Ki-67 index of <5%. Thus, the diagnosis in this case was benign schwannoma of the ascending colon.

Impaired glutathione redox system paradoxically suppresses angiotensin II-induced vascular remodeling.

BACKGROUND: Angiotensin II (AII) plays a central role in vascular remodeling via oxidative stress. However, the interaction between AII and reduced glutathione (GSH) redox status in cardiovascular remodeling remains unknown. METHODS: In vivo: The cuff-induced vascular injury model was applied to Sprague Dawley rats. Then we administered saline or a GSH inhibitor, buthionine sulfoximine (BSO, 30 mmol/L in drinking water) for a week, subsequently administered 4 more weeks by osmotic pump with saline or AII (200 ng/kg/minute) to the rats. In vitro: Incorporation of bromodeoxyuridine (BrdU) was measured to determine DNA synthesis in cultured rat vascular smooth muscle cells (VSMCs). RESULTS: BSO reduced whole blood GSH levels. Systolic blood pressure was increased up to 215 ± 4 mmHg by AII at 4 weeks (p<0.01), which was not affected by BSO. Superoxide production in vascular wall was increased by AII and BSO alone, and was markedly enhanced by AII+BSO. The left ventricular weight to body weight ratio was significantly increased in AII and AII+BSO as compared to controls (2.52 ± 0.08, 2.50 ± 0.09 and 2.10 ± 0.07 mg/g respectively, p<0.05). Surprisingly, the co-treatment of BSO totally abolished these morphological changes. Although the vascular circumferential wall stress was well compensated in AII, significantly increased in AII+BSO. The anti-single-stranded DNA staining revealed increasing apoptotic cells in the neointima of injured arteries in BSO groups. BrdU incorporation in cultured VSMCs with AII was increased dose-dependently. Furthermore it was totally abolished by BSO and was reversed by GSH monoethyl ester. CONCLUSIONS: We demonstrated that a vast oxidative stress in impaired GSH redox system totally abolished AII-induced vascular, not cardiac remodeling via enhancement of apoptosis in the neointima and suppression of cell growth in the media. The drastic suppression of remodeling may result in fragile vasculature intolerable to mechanical stress by AII.

Gastric cancer with multiple intramural metastases and metastasis to the small intestine which eventually developed Trousseau's syndrome: report of a case.

Here we report a rare case of Trousseau's syndrome in a patient with gastric cancer with multiple intramural metastases and metastasis to the small intestine. A 70 year-old male complaining of appetite loss and weight loss of 7 kg within 3 months was admitted to hospital. Esophagogastroduodenal endoscopy revealed an advanced gastric cancer at the pylorus almost occluding the outlet of the stomach, and multiple ulcerative lesions throughout the stomach. A biopsy showed poorly differentiated adenocarcinoma. The patient underwent total gastrectomy. During surgery, part of the distal ileum was found to be abnormally firm and approximately 1 m of the ileum with the cecum colon was resected. Pathologic examination confirmed poorly differentiated adenocarcinoma at the pylorus and multiple intramural metastases in most other areas of the stomach. Lymph node metastases were confirmed in 12 out of 40 harvested regional lymph nodes including one positive paraaortic lymph node. The resected ileum contained multiple tumors with ulceration. Massive lymphatic invasion in the stomach and the small intestine was observed, which strongly suggested lymphatic spread of the gastric cancer. The patient was discharged on post-operative day 21; however, 2 months after surgery, he developed multiple cerebral thromboembolisms and died 2 weeks later.

Cardiac stem cells with electrical stimulation improve ischaemic heart function through regulation of connective tissue growth factor and miR-378.

AIMS: In this study, we investigated whether pre-conditioning (PC) by electrical stimulation (EleS) induces cytoprotective effect on cardiac stem cells (CSCs) and determined its underlying molecular mechanisms. METHODS AND RESULTS: Sca-1(+) CSCs were isolated from male C57BL6 mice (12 weeks) hearts. PC of CSCs with EleS ((EleS)CSCs) was carried out for 3 h at 1.5 V followed by exposure to 300 µM H2O2 for 5 h. Cytoprotective effects and cell adhesion ability were significantly increased by EleS as evaluated by transferase-mediated dUTP nick-end labelling (TUNEL), lactate dehydrogenase (LDH) release assay, and adhesion assay. EleS increased phosphorylation of AKT, focal adhesion kinase (FAK), and glycogen synthase kinase (GSK3ß), as well as decreased caspase-3 cleavage. Interestingly, inhibition of AKT or FAK abolished the pro-survival effects of EleS. We found that connective tissue growth factor (Ctgf) was responsible for EleS-induced CSC survival and adhesion.The survival rate of (EleS)CSCs after transplantation in the infarcted myocardium was significantly increased together with improvement in cardiac function. Importantly, knockdown of Ctgf abolished EleS-induced cytoprotective effects and recovery of cardiac function. Furthermore, we identified miR-378 as a potential Ctgf regulator in (EleS)CSCs. CONCLUSION: EleS enhanced CSC survival in vitro and in vivo as well as functional recovery of the ischaemic heart through an AKT/FAK/CTGF signalling pathway. It is suggested that Ctgf and miR-378 are novel therapeutic targets for stem cell-based therapy.

Identification of small juvenile stem cells in aged bone marrow and their therapeutic potential for repair of the ischemic heart.

Stem cell-mediated cardiac regeneration is impaired with age. In this study, we identified a novel subpopulation of small juvenile stem cells (SJSCs) isolated from aged bone marrow-derived stem cells (BMSCs) with high proliferation and differentiation potential. SJSCs expressed mesenchymal stem cell markers, CD29(+)/CD44(+)/CD59(+)/CD90(+), but were negative for CD45(-)/CD117(-) as examined by flow cytometry analysis. SJSCs showed higher proliferation, colony formation, and differentiation abilities compared with BMSCs. We also observed that SJSCs significantly expressed cardiac lineage markers (Gata-4 and myocyte-specific enhancer factor 2C) and pluripotency markers (octamer-binding transcription factor 4, sex-determining region Y box 2, stage-specific embryonic antigen 1, and Nanog) as well as antiaging factors such as telomerase reverse transcriptase and sirtuin 1. Interestingly, SJSCs either from young or aged animals showed significantly longer telomere length as well as lower senescence-associated ß-galactosidase expression, suggesting that SJSCs possess antiaging properties, whereas aged BMSCs have limited potential for proliferation and differentiation. Furthermore, transplantation of aged SJSCs into the infarcted rat heart significantly reduced the infarction size and improved left ventricular function, whereas transplantation of aged BMSCs was less effective. Moreover, neovascularization as well as cardiomyogenic differentiation in the peri-infarcted area were significantly increased in the SJSC-transplanted group compared with the BMSC-transplated group, as evaluated by immunohistochemical analysis. Taken together, these findings demonstrate that SJSCs possess characteristics of antiaging, pluripotency, and high proliferation and differentiation rates, and, therefore, these cells offer great therapeutic potential for repair of the injured myocardium.

Knockout of the Na,K-ATPase α2-isoform in cardiac myocytes delays pressure overload-induced cardiac dysfunction.

The α2-isoform of the Na,K-ATPase (α2) is the minor isoform of the Na,K-ATPase expressed in the cardiovascular system and is thought to play a critical role in the regulation of cardiovascular hemodynamics. However, the organ system/cell type expressing α2 that is required for this regulation has not been fully defined. The present study uses a heart-specific knockout of α2 to further define the tissue-specific role of α2 in the regulation of cardiovascular hemodynamics. To accomplish this, we developed a mouse model using the Cre/loxP system to generate a tissue-specific knockout of α2 in the heart using ß-myosin heavy chain Cre. We have achieved a 90% knockout of α2 expression in the heart of the knockout mice. Interestingly, the heart-specific knockout mice exhibit normal basal cardiac function and systolic blood pressure, and in addition, these mice develop ACTH-induced hypertension in response to ACTH treatment similar to control mice. Surprisingly, the heart-specific knockout mice display delayed onset of cardiac dysfunction compared with control mice in response to pressure overload induced by transverse aortic constriction; however, the heart-specific knockout mice deteriorated to control levels by 9 wk post-transverse aortic constriction. These results suggest that heart expression of α2 does not play a role in the regulation of basal cardiovascular function or blood pressure; however, heart expression of α2 plays a role in the hypertrophic response to pressure overload. This study further emphasizes that the tissue localization of α2 determines its unique roles in the regulation of cardiovascular function.

Prostacyclin stimulated integrin-dependent angiogenic effects of endothelial progenitor cells and mediated potent circulation recovery in ischemic hind limb model.

BACKGROUND: Prostacyclin (PGI2) enhances angiogenesis, especially in cooperation with bone marrow (BM)-derived endothelial progenitor cells (EPCs). However, the mechanisms of PGI2 in EPC-mediated angiogenesis in vivo remain unclear. The purpose of this study was to clarify the role of PGI2 in EPC-mediated angiogenesis using BM-specific IP deletion mice. METHODS AND RESULTS: Hind limb ischemia (HLI) was induced in wild-type (WT) mice transplanted with IP-deleted BM (WT/BM(IP(-/-)). Recovery of blood flow (RBF) in WT/BM(IP(-/-)) was impaired for 28 days after HLI, whereas RBF in IP(-/-)/BM(WT) was attenuated for up to 7 days compared with WT/BM(WT). The impaired RBF in WT/BM(IP(-/-)) was completely recovered by intramuscular injection of WT EPCs but not IP(-/-) EPCs. The impaired effects of IP(-/-) EPCs were in accordance with reduced formation of capillary and arterioles in ischemic muscle. An ex vivo aortic ring assay revealed that microvessel formation was enhanced by accumulation/adhesion of EPCs to perivascular sites as pericytes. IP(-/-)EPCs, in which expression of integrins was decreased, had impaired production of angiogenic cytokines, adhesion to neovessels and their angiogenic effects. The small-interfering RNA (siRNA)-mediated knockdown of integrin ß1 in WT EPCs attenuated adhesion to microvessels and their in vivo and in vitro angiogenic effects. CONCLUSIONS: PGI2 may induce persistent angiogenic effects in HLI through adhesion of EPCs to perivascular sites of neovessels via integrins in addition to paracrine effects.

Spontaneous resolution of an accidental total coronary occlusion.

In December 2007, a woman was involved in a traffic accident. At first, her vital signs were normal, but electrocardiogram showed ST-segment elevation in the inferior leads. She was diagnosed as a blunt chest trauma-induced myocardial infarction. Her right coronary angiography showed total occlusion. She underwent an emergency coronary artery bypass surgery; 64-multi-detector-row computed tomography (64-MDCT) demonstrated an intravascular protruding lesion, which suggested subintimal hematoma. One month later, repeat coronary angiogram showed spontaneous recanalization, and 64-MDCT showed no discontinuous vessel wall. Coronary artery occlusion secondary to blunt chest trauma is rare, and it's even rarer to have spontaneous recanalization.