Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2B2C

We present a local probe study of the magnetic superconductor, ErNi$_2$B$_2$C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi$_2$B$_2$C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth $\lambda$ and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. In addition, we estimate the absolute pinning force of Abrikosov vortices, which shows a position- and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation

TRAIL Enhances Apoptosis of Human Hepatocellular Carcinoma Cells Sensitized by Hepatitis C Virus Infection: Therapeutic Implications

Hepatitis C virus (HCV) infection causes chronic liver diseases leading to hepatocellular carcinoma (HCC) and liver failure. We have previously shown that HCV sensitizes hepatocytes to mitochondrial apoptosis via the TRAIL death receptors DR4 and DR5. Although TRAIL and its receptors are selective targets for cancer therapy, their potential against HCC with chronic HCV infection has not been explored yet. Here we show that HCV induces DR4/DR5-dependent activation of caspase-8 leading to elevation of apoptotic signaling in infected cells and also present TRAIL effect in HCV-induced apoptotic signaling. HCV induced proteolytic cleavage of caspase-9 by stimulating DR4 and DR5, resulting in subsequent cleavage of caspase-3. Further, HCV-induced proteolytic cleavage in caspase-8, caspase-9, and caspase-3 was enhanced in the presence of recombinant TRAIL. HCV-induced cleavage in caspase-9 and increase in caspase-3/7 activity was completely suppressed by silencing of either DR4 or DR5. Perturbing DR4/DR5-caspase-8 signaling complex by silencing DR4 and DR5 or by chemical inhibitor specific to caspase-8 led to decrease of HCV-induced cleavage of poly(ADP-ribose) polymerase (PARP), a substrate for caspase-3 during apoptosis, indicating the functional role of caspase-8 in HCV-induced apoptotic signaling network. Furthermore, TRAIL enhanced PARP cleavage in apoptotic response induced by HCV infection, indicating the effect of TRAIL for the induction of selective apoptosis of HCC cells infected with HCV. Given the importance of apoptosis in HCC development, our data suggest that HCV-induced DR4 and DR5 may be considered as an attractive target for TRAIL therapy against HCC with chronic HCV infection

Pulmonary artery banding before the Damus-Kaye-Stansel procedure

Subaortic stenosis (SAS) in a single ventricle leads to myocardial hypertrophy and compromises Fontan results. Moreover, controversy exists concerning the optimal surgical strategy for relieving SAS. We have applied pulmonary artery banding (PAB) before the Damus-Kaye-Stansel procedure (DKS), and here we analyze factors that influence systemic ventricular compliance. Thirteen patients underwent PAB before DKS. Median PAB duration was 5.5 months (range, 20 days to 17.7 months). Procedures administered concomitantly with DKS were Blalock-Taussig shunt (n = 6), bidirectional cavopulmonary shunt (n = 5), and Fontan operation (n = 2). All survived and were doing well after a median follow-up 2.7 years. Cardiac catheterization before DKS showed that the mean pressure gradient across the systemic ventricular outflow tract and PAB were 20.6 +/- 10.1 and 67.4 +/- 10.2 mmHg, respectively. After DKS, systemic ventricular end diastolic pressure (SVEDP) was significantly correlated with PAB duration (r = 0.65, p = 0.022), but not with PAB or systemic ventricle outflow tract pressure gradients. After DKS, SVEDP decreased or fell to within the range in patients with PAB duration less than 7 months (p < 0.05). Seven patients had a successful Fontan operation, and 6 without risk factors are waiting operation. SVEDP was found to be correlated with PAB duration, and our findings indicate that short-term PAB can be considered a safe option in patients with a single ventricle and SAS

Midterm follow-up of the status of Gore-Tex graft after extracardiac conduit Fontan procedure

OBJECTIVE: Extracardiac conduit Fontan procedure has some theoretical advantages over other types of Fontan procedures, such as optimized flow dynamics, a lower frequency of arrhythmias, and technical ease of procedure. However, lack of growth potential and thrombogenicity of the artificial conduit is the main concern and can possibly lead to reoperation for the conduit stenosis. In this study, we investigated the change and the status of the Gore-Tex graft used in extracardiac conduit Fontan procedure. METHODS: Between 1996 and 2005, 154 patients underwent extracardiac conduit Fontan procedure using Gore-Tex graft. Among these, 46 patients underwent cardiac catheterization during follow-up period. We measured the internal diameter of the conduit and inferior vena cava angiographically. RESULTS: Mean follow-up duration was 36.1+/-19.7 months. The conduit diameter used was 16 mm in 10 patients, 18 mm in 16, 20 mm in 14, 22 mm in 4, and 24 mm in 2 patients. The mean conduit-to-inferior vena cava cross-sectional area ratio was 1.25+/-0.33. According to the conduit size used, this ratio was 1.03+/-0.17 for 16 mm conduits, 1.33+/-0.37 for 18 mm, 1.33+/-0.36 for 20 mm, 1.28+/-0.26 for 22 mm, and 1.05+/-0.06 for 24 mm conduits (p<0.05, 16 mm vs 18 mm and 20 mm). The mean percent decrease of the conduit cross-sectional area was 14.3+/-8.5%, and this did not differ significantly according to the conduit size (p=0.82). Follow-up duration and the percent decrease of the conduit cross-sectional area did not show significant correlation (r=0.22, p=0.14). There was no reoperation due to conduit stenosis. CONCLUSIONS: During midterm follow-up of about 3 years, the conduit cross-sectional area decreased by 14%, and this did not differ according to the conduit size used. The extent of decrease of the conduit cross-sectional area remained stable irrespective of the follow-up duration. Sixteen millimeters conduit showed no evidence of clinically significant stenosis, but careful follow-up is warranted because of the possible conduit stenosis relative to the patients' somatic growth

One-stage total repair of aortic arch anomaly using regional perfusion

OBJECTIVE: Primary repair of aortic arch obstructions and associated cardiac anomalies is a surgical challenge in neonates and infants. Deep hypothermic circulatory arrest prolongs myocardial ischemia and might induce cerebral and myocardial dysfunction. METHODS: From March 2000 to December 2005, 69 neonates or infants with aortic arch anomaly underwent one-stage biventricular repair with continuous cerebral perfusion in the presence of a nonworking beating heart using the dual perfusion technique on the innominate artery and aortic root. Preoperative diagnoses of arch anomaly comprised aortic coarctation (n=54) or an interrupted aortic arch (n=15). Combined anomalies were ventricular septal defect (n=52), anomalous origin of the right pulmonary artery from ascending aorta (n=3), hypoplastic left heart syndrome (n=2), truncus arteriosus (n=2), atrioventricular septal defect (n=2), double outlet right ventricle (n=1), total anomalous pulmonary venous return (n=1), partial anomalous pulmonary venous return (n=1), and aortic stenosis (n=1). RESULTS: The mean regional perfusion time was 27.8+/-9.8 min. There was no operative mortality. Postoperative low cardiac output was present in four patients (5.8%). A neurologic complication was noted in one patient (1.5%) who developed transient chorea, but recovered completely. During 32.8+/-17.5 months of follow-up, one late death (1.5%) occurred. There was neither reoperation associated with arch anomaly nor recoarctation except in one patient. One patient developed left main bronchial compression necessitating aortopexy. CONCLUSIONS: One-stage total arch repair using our regional perfusion technique is an excellent method that may minimize neurologic and myocardial complications without mortality. Our surgical strategy for arch anomaly has a low rate of residual and recurrent coarctation when performed in neonates and infants

Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2 B2 C

We present a local probe study of the magnetic superconductor ErNi2B2C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi2B2C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth λ and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. In addition, we estimate the absolute pinning force of Abrikosov vortices, which shows a position dependence and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation. © 2015 American Physical Society. ©2015 American Physical Society1551sciescopu

Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2 B2C

We present a local probe study of the magnetic superconductor ErNi2B2C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi2B2C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth λ and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. In addition, we estimate the absolute pinning force of Abrikosov vortices, which shows a position dependence and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation.This article is published as Wulferding, Dirk, Ilkyu Yang, Jinho Yang, Minkyung Lee, Hee Cheul Choi, Sergey L. Bud'ko, Paul C. Canfield, Han Woong Yeom, and Jeehoon Kim. "Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2B2C." Physical Review B 92, no. 1 (2015): 014517. DOI: 10.1103/PhysRevB.92.014517. Posted with permission.</p