Experimental proof of the reciprocal relation between spin Peltier and spin Seebeck effects in a bulk YIG/Pt bilayer.

We verify for the first time the reciprocal relation between the spin Peltier and spin Seebeck effects in a bulk YIG/Pt bilayer. Both experiments are performed on the same YIG/Pt device by a setup able to accurately determine heat currents and to separate the spin Peltier heat from the Joule heat background. The sample-specific value for the characteristics of both effects measured on the present YIG/Pt bilayer is (6.2 ± 0.4) × 10-3 KA-1. In the paper we also discuss the relation of both effects with the intrinsic and extrinsic parameters of YIG and Pt and we envisage possible strategies to optimize spin Peltier refrigeration.

Cross-modality Accuracy of Dual-step, Prospectively Electrocardiography-triggered Dual-source Computed Tomorgaphy Compared With Same-day Echocardiography and Cardiac Magnetic Resonance Imaging in the Follow-up of Heart-transplant Patients.

PURPOSE: An accurate evaluation of left ventricular volumes, mass, and ejection fraction (EF) and an early exclusion or detection of significant coronary artery disease or cardiac allograft vasculopathy are mandatory for clinical management and prognosis assessment of heart-transplanted patients (HTP). The purpose of this article was to evaluate the role of dual-step prospective electrocardiography-triggered Dual-Source CT (pECGdual-step-DSCT) in HTP for the assessment of left-ventricular function, in comparison with echocardiography (echo) and cardiac magnetic resonance (CMR) performed on the same day, and of the coronary arteries as well. MATERIALS AND METHODS: Left-ventricular EF, end-diastolic volume, end-systolic volume, stroke volume, cardiac output (CO), and mass were assessed in 11 HTP by pECGdual-step-DSCT in comparison with CMR and echo performed on the same day. During all the examinations, the heart rate was recorded. CT coronary artery assessment was also performed. RESULTS: Heart rate was lower during DSCT (75.6±7.8 bpm; P<0.001). EF resulted slightly lower for DSCT (55.7%±5.0%; P≥0.05) in comparison with CMR (57.8%±5.3%; P≥0.05) and echo (59.2%±5.6%; P≥0.05). DSCT showed statistically significant higher end-diastolic volume (153.7±24.2 mL), end-systolic volume (67.8±11.5 mL), and stroke volume (85.9±17.6 mL) (P<0.01 up to 0.001) than CMR, but with a high correlation (P<0.001). Cardiac output was almost similar for DSCT versus CMR, with a very high correlation coefficient (r=0.914; P<0.001). DSCT showed higher mass values than CMR (P<0.001), but with a high correlation (r=0.866; P<0.001). DSCT versus echo results were less correlated. No significant coronary artery disease was detected. CONCLUSION: pECGdual-step-DSCT allows reliable assessment of left-ventricular function in HTP, with good agreement and correlation with CMR, within a global diagnostic approach including coronary artery evaluation in one single-volume acquisition.

[QT dispersion and myonecrosis after stent percutaneous coronary intervention]. / Dispersione dell'intervallo QT e miocardionecrosi dopo stenting coronarico.

BACKGROUND: QT dispersion (QTd) is the difference between the maximum and the minimum QT interval in the 12-lead ECG. There is currently no information on the relationship between QTd and creatine kinase (CK)-MB release in patients undergoing percutaneous coronary intervention (PCI). METHODS: Among 118 patients undergoing successful PCI stenting, QTd and corrected QTd (QTdc) were measured at standard 12-lead ECG before PCI and at 6 and 18 hours after PCI. The median of QTdc variation (deltaQTdc = baseline QTdc - QTdc at 6 hours) was 9.5 ms (range -48 / +89 ms). Patients were divided into two groups according to deltaQTdc: group A "recoverers" (deltaQTdc > 9.5 ms, n = 59, 50%), group B "non-recoverers" (deltaQTdc < 9.5 ms, n = 59, 50%). CK-MB release was compared in the two groups. RESULTS: Eighty-three percent of patients were male, with mean age of 62 years (range 41-80 years). Unstable angina was present in 35% of cases, with similar distribution in the two groups. PCI was performed in 1.94 lesions/patient with the implantation of 1.6 stent/patient. Compared to baseline, a reduction in both QTc and QTdc was documented at 6 and 18 hours after PCI (p < 0.05). Periprocedural variations (CK-MB > 2 upper limit of normal) was detected in 4 patients (7%) of group A and 12 patients (20%) in group B (p = 0.06). Peak CK-MB release was significantly lower in group A (13 +/- 14.3 IU/l) compared to group B (23.2 +/- 35 IU/l, p < 0.05). CONCLUSIONS: After successful coronary stenting there is a rapid normalization of QTd and QTdc. The lack of recovery of both QTd and QTdc is related to minor elevations of CK-MB and may therefore be further explored as a useful non-invasive marker of heterogeneous reperfusion after PCI.

Modulation of aspirin-insensitive eicosanoid biosynthesis by 6-methylprednisolone in unstable angina.

BACKGROUND: The evidence that inflammation plays a pivotal role in the pathophysiology of acute coronary syndromes prompted us to investigate the effects of glucocorticoid treatment on leukotriene (LT) C4 and thromboxane (TX) A2 biosynthesis in unstable angina. METHODS AND RESULTS: Urinary LTE4 and 11-dehydro-TXB2 were significantly higher in 12 patients with unstable angina than in 12 patients with stable angina and 12 patients with nonischemic chest pain. Furthermore, we randomized the unstable angina patients to receive intravenous 6-methylprednisolone (6-MP; 1 mg/kg BID for 2 days) or matching placebo and collected 12 consecutive 6-hour urine samples before and during the infusions. LTE4 excretion showed a time-dependent decrease in the 6-MP group but did not decrease during placebo. Furthermore, during myocardial ischemia, LTE4 was significantly higher before 6-MP infusion than during steroid therapy. In contrast, 11-dehydro-TXB2 did not differ significantly during 6-MP versus placebo. Myocardial ischemia elicited by stress test in the stable angina patients was not accompanied by any change in LTE4 and 11-dehydro-TXB2, thus ruling out a role of ischemia per se in the induction of increased eicosanoid production. CONCLUSIONS: Increased production of vasoactive LT and TX may occur in unstable angina despite conventional antithrombotic and antianginal treatment. Glucocorticoids can suppress LTC4 biosynthesis in the short term and may provide an interesting tool to explore the pathophysiological significance of inflammatory cell activation in this setting.