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The development of electric resistance is a key factor affecting the performance of conductive concrete, especially the electrical-thermal performance. In this work, the effects of different influencing factors (including the water-to-binder ratio, coarse aggregate content and carbon fiber (CF) content) on the electric resistance of conductive concrete were systematically investigated. At the same time, ohmic heating (OH) curing was applied to fabricate CF-reinforced conductive concrete (CFRCC) under a negative temperature environment at -20 °C. The effects of different factors on the electrothermal properties (curing temperature and conductive stability) of the samples were studied. The mechanical strengths of the CFRCC cured by different curing conditions were also tested, and the feasibility of OH curing for preparing CFRCC in a negative-temperature environment was verified at various electric powers. This work aims to give new insights into the effects of multiple factors on the performance of CFRCC for improved concrete construction in winter.
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Water electrolysis driven by "green electricity" is an ideal technology to realize energy conversion and store renewable energy into hydrogen. With the development of proton exchange membrane (PEM), water electrolysis in acidic media suitable for many situations with an outstanding advantage of high gas purity has attracted significant attention. Compared with hydrogen evolution reaction (HER) in water electrolysis, oxygen evolution reaction (OER) is a kinetic sluggish process that needs a higher overpotential. Especially in acidic media, OER process poses higher requirements for the electrocatalysts, such as high efficiency, high stability and low costs. This review focuses on the acidic OER electrocatalysis, reaction mechanisms, and critical parameters used to evaluate performance. Especially the modification strategies applied in the design and construction of new-type electrocatalysts are also summarized. The characteristics of traditional noble metal-based electrocatalysts and the noble metal-free electrocatalysts developed in recent decades are compared and discussed. Finally, the current challenges for the most promising acidic OER electrocatalysts are presented, together with a perspective for future water electrolysis.
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This randomized, double-blind study evaluated the short-term effects and safety of perioperative retrograde autologous priming (RAP) for cardiopulmonary bypass (CPB) in patients with cardiac replacement surgery to determine if this approach is a better substitute for crystal liquids priming in patients with valvular heart disease. We observed that RAP significantly decreased the actual priming volume, preserved the hematocrit and hemoglobin level during CPB to a certain degree, and decreased lactate accumulation in CPB period. Moreover, RAP lowered the volume of transfusion and dosage blood products. Thus, our results showed that RAP approach effectively improved tissue perfusion and lowered intraoperative Lac levels, by reducing the hemodilution, which safely and reliably improve the microcirculation perfusion.
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Puente Cardiopulmonar , Enfermedades de las Válvulas Cardíacas/cirugía , Adulto , Pérdida de Sangre Quirúrgica , Transfusión Sanguínea , Método Doble Ciego , Femenino , Hematócrito , Hemodilución , Hemoglobinas/metabolismo , Humanos , Ácido Láctico/metabolismo , Cristales Líquidos/química , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
After the publication of the article, the authors decided they wished to retract their manuscript for the following reasons. We wish to retract our research article entitled 'Generation of induced pluripotent stem cells using skin fibroblasts from patients with myocardial infarction under feeder-free conditions' published on the Molecular Medicine Reports 9: 837-842, 2014. In this article, we generated human iPSCs from skin fibroblasts from myocardial infarction patients in feeder-independent conditions. However, in subsequent researches, all of the cells generated and believed to be iPSCs showed negative expression of the pluripotent markers, Nanog and Rex1, and the cell surface marker, SSEA-1 and SSEA-4. Therefore we think the established iPS cells might not be real pluripotent stem cells. Based on the above mentioned, we ascertained that there must have some serious disadvantages in our design of experiment fundamentally. As a result, all authors involved unanimously agreed to retract this article and redesign our experiment. We deeply apologize to the readers for any inconvenience caused by this retraction. [the original article was published in the Molecular Medicine Reports 9: 837-842, 2014 DOI: 10.3892/mmr.2014.1885].
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Myocardial infarction (MI) is an increasing medical problem; however, its pathogenesis has yet to be elucidated and more effective treatment strategies are required. Induced pluripotent stem cells (iPSCs) were recently successfully generated using human somatic cells transfected with four transcription factors. The present study aimed to generate iPSCs from cells from patients with myocardial infarction. Six patients who had been diagnosed with myocardial infarction were enrolled in this study. The fibroblast cells from the biopsied skin were reprogrammed using octamer-binding transcription factor 4 (Oct4), SRY-related HMG-box gene 2 (Sox2), Kruppel-like factor 4 (Klf4) and cellular myelocytomatosis oncogene (cMyc) transcription factors. The generated cells were identified by karyotyping, in vitro and in vivo differentiation ability and staining for specific markers. These human MIiPSCs expressed pluripotent genes and cell surface markers, and exhibited normal proliferation. The iPSCs also showed in vivo and in vitro differentiation ability, as indicated by teratoma and embryoid body formation, respectively. Moreover, the iPSCs differentiated into cardiomyocytes and neuronal cells. In conclusion, human iPSCs were successfully generated from skin fibroblasts from patients with MI under feederindependent conditions, which increases their potential suitability for clinical applications. These results may encourage further study of MI pathogenesis and facilitate the development of safe downstream clinical applications of iPSCbased cell therapies.
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AIM: It has previously been reported that ISLET1 (ISL1) plays a fundamental role in cardiac morphogenesis. This study investigated the possible association between variants in the ISL LIM homeobox 1 (ISL1) gene and congenital ventricular septal defect (VSD) in a Chinese cohort. METHODS: A total of 512 congenital VSD patients and 612 unrelated age- and sex-matched healthy control subjects were enrolled in this study. Genotypes for three variants in ISL1 (rs3762977, IVS1+17C>T, and rs1017) were determined. RESULTS: We found that the rs3762977 and IVS+17C>T variants were closely associated with the risk of developing VSD. Carriers of the GG genotype of rs3762977 and the TT genotype of IVS+17C>T were less likely to have VSD, whereas variants in rs1701 did not affect the VSD risk. The haplotypes rs3762977G-rs1017A-IVS+17T and rs3762977G-rs1017T-IVS+17T represented a protective effect against VSD. None of these ISL1 variants showed any association with VSD type according to defect location and VSD severity according to defect size. CONCLUSION: These findings suggest that ISL1 genetic polymorphisms are associated with occurrence of VSD, thus they may be useful as molecular markers for prediction of VSD.
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Defectos del Tabique Interventricular/genética , Proteínas con Homeodominio LIM/genética , Factores de Transcripción/genética , Adolescente , Adulto , Pueblo Asiatico , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Predisposición Genética a la Enfermedad/genética , Genotipo , Humanos , Lactante , Masculino , Adulto JovenRESUMEN
OBJECTIVE: Clinical trials of cardiac cell therapy have indicated limited benefits in aging patients, even though preclinical studies using young animals consistently reported significant improvements. Animal studies have demonstrated reduced efficacy of donor cells isolated from older individuals. Here, we evaluated the effects of donor age on the function of human mesenchymal stem cells (hMSCs) in the context of cell therapy for ischemic cardiomyopathy. METHODS: In vitro, we compared the growth and clonogenic potential of hMSCs isolated from young or old patients (1-5 vs. 50-70 years old). In vivo, we injected young or old hMSCs (2.0 x 10(6)) (or medium) into the infarcted myocardia of immunosuppressed rats immediately after coronary artery ligation (myocardial infarction [MI]). We assessed cardiac function (echocardiography) at 1, 2, and 4 weeks after MI, and myocardial matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) levels at 1 week. RESULTS: In vitro, growth and colony-forming unit fibroblast (CFU-F) formation were markedly diminished in old hMSCs (p < 0.001 and p < 0.05, respectively, vs. young). In vivo, compared with old hMSCs or medium, young hMSCs best preserved ejection fraction, fractional shortening (p < 0.05), and left ventricular end-diastolic and end-systolic volumes (p < 0.01). Recipients of young hMSCs also exhibited increases in vascular density and TIMP-3 protein levels and activity (p < 0.05), and decreases in MMP protein levels and activity (p < 0.05). CONCLUSIONS: The regenerative capacity of hMSCs was significantly influenced by age. Transplanting young hMSCs improved functional outcomes after an MI by preventing matrix degradation and promoting angiogenesis. The clinical implication is that aged patients require an optimized source of stem cells for treatment.
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Factores de Edad , Células Madre Mesenquimatosas/citología , Infarto del Miocardio/cirugía , Trasplante de Células Madre , Anciano , Animales , Secuencia de Bases , Preescolar , Cartilla de ADN , Ecocardiografía , Humanos , Técnicas In Vitro , Lactante , Masculino , Persona de Mediana Edad , Infarto del Miocardio/fisiopatología , Neovascularización Fisiológica , Ratas , Ratas Wistar , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
This study assessed the potential therapeutic efficacy of adipose-derived stem cells (ASCs) on infarcted hearts. Myocardial infarction was induced in rat hearts by occlusion of the left anterior descending artery (LAD). One week after LAD occlusion, the rats were divided into three groups and subjected to transplantation of ASCs or transplantation of cell culture medium (CCM) or remained untreated. During a 1-mo recovery period, magnetic resonance imaging showed that the ASC-treated hearts had a significantly greater left ventricular (LV) ejection fraction and LV wall thickening than did the CCM-treated and untreated hearts. The capillary density in infarct border zone was significantly higher in the ASC-treated hearts than in the CCM-treated and untreated hearts. However, only 0.5% of the ASCs recovered from the ASC-treated hearts were stained positive for cardiac-specific fibril proteins. It was also found that ASCs under a normal culture condition secreted three cardiac protective growth factors: vascular endothelial growth factor, hepatocyte growth factor, and insulin-like growth factor-1. Results of this study suggest that ASCs were able to improve cardiac function of infarcted rat hearts. Paracrine effect may be the mechanism underlying the improved cardiac function and increased capillary density.
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Insuficiencia Cardíaca/terapia , Imagen por Resonancia Magnética , Miocitos Cardíacos/citología , Trasplante de Células Madre/métodos , Células Madre/citología , Grasa Subcutánea/citología , Animales , Biomarcadores/metabolismo , Capilares/fisiología , Diferenciación Celular , Circulación Coronaria/fisiología , Modelos Animales de Enfermedad , Femenino , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/prevención & control , Factor de Crecimiento de Hepatocito/genética , Factor I del Crecimiento Similar a la Insulina/genética , Proteínas de la Membrana/metabolismo , Infarto del Miocardio/patología , Infarto del Miocardio/terapia , Miocitos Cardíacos/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas Lew , Células Madre/metabolismo , Factor A de Crecimiento Endotelial Vascular/genética , Función Ventricular Izquierda , Remodelación Ventricular/fisiologíaAsunto(s)
Defectos del Tabique Interatrial/cirugía , Revascularización Miocárdica/efectos adversos , Complicaciones Posoperatorias/etiología , Adulto , Remoción de Dispositivos , Falla de Equipo , Femenino , Migración de Cuerpo Extraño/cirugía , Humanos , Revascularización Miocárdica/instrumentaciónRESUMEN
OBJECTIVE: To investigate the value of ischemic myocardial viability assessment using interleaved T1-T2* magnetic resonance imaging. METHODS: The left anterior descending coronary arteries (LAD) were occluded for 2 hours, followed by 1-hour reperfusion in 7 pigs. The hearts were then removed and perfused with a mixture of pig blood and crystalloid solution in 1:1 ratio. T1 relaxation times of the myocardium were measured with a TurboFLASH inversion-recovery sequence. The contrast agent, Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was then injected as a bolus into the aortic perfusion line (0.05 mmol/kg body wt). The first pass of the contrast agent through the heart was followed using the interleaved T1-T2* imaging sequence. Once the concentration of Gd-DTPA was in an equilibrium state, T1 relaxation times were measured again. RESULTS: The percentage recovery of T2* intensity (PRT2*) at the maximum T1 intensity measured during the first pass of the contrast agent with the interleaved T1-T2* imaging was statistically different in normal myocardium (37 +/- 11)%, infarct rim (90 +/- 15)% and infarct core (100 +/- 5)%, F = 66.585, P = 0.000. Moreover, the infarcted regions shown on PR(T2)* maps matched well with the infarcted myocardium measured by TTC staining. The median of T(1) relaxation time in normal region, infarct rim and infarct core was 531 ms, 541 ms and 1298 ms, respectively (H = 6.284, P = 0.043). However, normal region could not be differentiated from infarct rim with T1 relaxation times (q = 0.082, P = 0.775). CONCLUSION: Infarcted myocardium and ischemic myocardial viability can be correctly identified and evaluated by the interleaved T1-T2* magnetic resonance imaging in this model.
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Imagen por Resonancia Magnética/métodos , Infarto del Miocardio/diagnóstico , Animales , Modelos Animales de Enfermedad , Femenino , Masculino , Contracción Miocárdica , Isquemia Miocárdica/diagnóstico , Miocardio/patología , PorcinosRESUMEN
BACKGROUND AND AIM OF THE STUDY: Simultaneous antegrade/retrograde cardioplegia (SARC) has been employed frequently during cardiac surgery to preserve the jeopardized myocardium. However, retrograde perfusion of SARC may interfere with myocardial drainage and disrupt myocardial fluid homeostasis, which may affect the myocardial energy metabolism and contractile function. The study was, therefore, designed to assess the effects of SARC on myocardial fluid homeostasis, cellular volumes, and energy metabolism. METHODS: Eight isolated pig hearts were subjected to a protocol consisting of a 20-minute control perfusion, 120-minute SARC, and 20-minute reperfusion. The myocardial water content was monitored using near-infrared spectroscopy. Phosphorus-31 magnetic resonance ((31)P MR) spectroscopy was used to monitor the volumes of both intracellular and extracellular compartments and assess myocardial energy metabolism. RESULTS: The near-infrared spectra showed that the 120-min SARC resulted in a 60 +/- 12% increase in the myocardial water content. (31)P MR spectra showed a 36 +/- 4% increase in the intracellular compartment and a 54 +/- 8% increase in the extracellular compartment during SARC relative to their initial volumes measured during control perfusion (100%). However, the myocardial energy metabolites (adenosine triphosphate [ATP] and phosphocreatine [PCr]) remained unchanged during the 120-minute SARC. Moreover, during reperfusion, the hearts showed an almost complete recovery in the left ventricular-developed pressure. CONCLUSIONS: A prolonged SARC resulted in water accumulation in both extracellular and intracellular compartments in the normal myocardium. Although its detrimental effect on tissue fluid homeostasis did not jeopardize the myocardial energy metabolism, a prolonged use of SARC should be avoided, particularly in the diseased hearts.