Application of self-supervised approaches to the classification of X-ray diffraction spectra during phase transitions.

Spectroscopy and X-ray diffraction techniques encode ample information on investigated samples. The ability of rapidly and accurately extracting these enhances the means to steer the experiment, as well as the understanding of the underlying processes governing the experiment. It improves the efficiency of the experiment, and maximizes the scientific outcome. To address this, we introduce and validate three frameworks based on self-supervised learning which are capable of classifying 1D spectral curves using data transformations preserving the scientific content and only a small amount of data labeled by domain experts. In particular, in this work we focus on the identification of phase transitions in samples investigated by x-ray powder diffraction. We demonstrate that the three frameworks, based either on relational reasoning, contrastive learning, or a combination of the two, are capable of accurately identifying phase transitions. Furthermore, we discuss in detail the selection of data augmentation techniques, crucial to ensure that scientifically meaningful information is retained.

Improvement of Left Ventricular Graft Function Using an Iron-Chelator-Supplemented Bretschneider Solution in a Canine Model of Orthotopic Heart Transplantation.

Demand for organs is increasing while the number of donors remains constant. Nevertheless, not all organs are utilized due to the limited time window for heart transplantation (HTX). Therefore, we aimed to evaluate whether an iron-chelator-supplemented Bretschneider solution could protect the graft in a clinically relevant canine model of HTX with prolonged ischemic storage. HTX was performed in foxhounds. The ischemic time was standardized to 4 h, 8 h, 12 h or 16 h, depending on the experimental group. Left ventricular (LV) and vascular function were measured. Additionally, the myocardial high energy phosphate and iron content and the in-vitro myocyte force were evaluated. Iron chelator supplementation proved superior at a routine preservation time of 4 h, as well as for prolonged times of 8 h and longer. The supplementation groups recovered quickly compared to their controls. The LV function was preserved and coronary blood flow increased. This was also confirmed by in vitro myocyte force and vasorelaxation experiments. Additionally, the biochemical results showed significantly higher adenosine triphosphate content in the supplementation groups. The iron chelator LK614 played an important role in this mechanism by reducing the chelatable iron content. This study shows that an iron-chelator-supplemented Bretschneider solution effectively prevents myocardial/endothelial damage during short- as well as long-term conservation.

How to report incidental findings from population whole-body MRI: view of participants of the German National Cohort.

OBJECTIVES: In the German National Cohort (GNC), 30,000 individuals are examined with whole-body MRI (wbMRI), of which about 3000 participants are expected to receive an incidental finding (IF) disclosure. In order to get feedback from participants and to evaluate the IF-management procedure of the wbMRI substudy, a follow-up questionnaire was developed. This single-center pilot trial was aimed to get a first impression on feasibility reproducibility and validity of such a survey in order to take necessary adjustments before initiating the survey among several thousand participants. METHODS: The questionnaires were sent out in test-retest manner to 86 participants who received a wbMRI examination in January-February 2016 at the imaging center in Neubrandenburg. The ratio of participants with and without IF notification was 1:1. Descriptive statistics was performed. RESULTS: A first response of 94% and completion proportion of 99% were achieved. Participants were satisfied with the examination procedure. Ninety-five percent of participants considered it very important to receive notification of IFs. Participants reported minimal stress levels while waiting for a possible IF notification letter, but high stress levels when an IF letter was received. Phrasing of the IF reports was rated in 97% as well understandable and in 55% as beneficial to health status. CONCLUSIONS: This questionnaire will serve researchers within the GNC as a fundamental instrument not only for quality management analyses but also for the investigation of still unacknowledged scientific and ethical questions contributing to evidence-based guidelines concerning the complex approach to IFs in future population-based imaging. KEY POINTS: • Evidence-based guidelines for reporting incidental findings in population whole-body MRI are lacking. • Pilot-testing of a questionnaire for the evaluation of practical and ethical aspects of the procedure to report incidental findings in the German National Cohort shows a high level of acceptance and high return rate by participants. • Participants reported minimal stress levels while waiting for a possible incidental finding notification letter, which increased significantly, when such a letter was received.

Is internal thoracic artery resistant to reperfusion injury? Evaluation of the storage of free internal thoracic artery grafts.

OBJECTIVES: The in situ internal thoracic artery (ITA) is recognized as the best conduit for coronary artery bypass surgery. The ITA-if it is used as an in situ graft-has a much higher late patency rate than any other arterial graft, including a free ITA graft. We sought to determine if the use of the ITA as an in situ/free graft and its storage in preservation solutions, have an effect on endothelial function. METHODS: The ITA was harvested as either a free or in situ graft in a porcine model. Free grafts were stored in different preservation solutions (saline, Custodiol and Tiprotec [both Köhler Chemie GmbH, Bensheim, Germany]). The ITA was anastomosed off pump to the left anterior descending artery (as in situ/free graft). Freshly harvested ITA served as a control. After 2 hours of reperfusion, the implanted grafts were harvested. The assessment of endothelial function, histopathological analysis, and gene expression were performed. RESULTS: Endothelial function and integrity were severely impaired after reperfusion in the free ITA groups, however, it was partially preserved in the Tiprotec group. Reperfusion injury resulted in increased nitro-oxidative stress, DNA breakage, vascular cell adhesion protein 1, intercellular adhesion molecule-1, and caspase-3 scores, and a decreased endothelial nitric oxide synthase score in the free ITA groups. The in situ ITA graft showed no signs of injury. mRNA levels were significantly altered among the groups. CONCLUSIONS: An early, severe endothelial dysfunction of the stored, free ITA as described, could be completely prevented by the use of an in situ ITA graft. Tiprotec might be a feasible option for storage of free arterial grafts during coronary artery bypass grafting.

Myocardial reverse remodeling after pressure unloading is associated with maintained cardiac mechanoenergetics in a rat model of left ventricular hypertrophy.

Pressure unloading represents the only effective therapy in increased afterload-induced left ventricular hypertrophy (LVH) as it leads to myocardial reverse remodeling (reduction of increased left ventricular mass, attenuated myocardial fibrosis) and preserved cardiac function. However, the effect of myocardial reverse remodeling on cardiac mechanoenergetics has not been elucidated. Therefore, we aimed to provide a detailed hemodynamic characterization in a rat model of LVH undergoing pressure unloading. Pressure overload was induced in Sprague-Dawley rats by abdominal aortic banding for 6 (AB 6th wk) or 12 wk (AB 12th wk). Sham-operated animals served as controls. Aortic debanding procedure was performed after the 6th experimental week (debanded 12th wk) to investigate the regression of LVH. Pressure unloading resulted in significant reduction of LVH (heart weight-to-tibial length ratio: 0.38 ± 0.01 vs. 0.58 ± 0.02 g/mm, cardiomyocyte diameter: 18.3 ± 0.1 vs. 24.1 ± 0.8 µm debanded 12th wk vs. AB 12th wk, P < 0.05), attenuated the extracellular matrix remodeling (Masson's score: 1.37 ± 0.13 vs. 1.73 ± 0.10, debanded 12th wk vs. AB 12th wk, P < 0.05), provided protection against the diastolic dysfunction, and reversed the maladaptive contractility augmentation (slope of end-systolic pressure-volume relationship: 1.39 ± 0.24 vs. 2.04 ± 0.09 mmHg/µl, P < 0.05 debanded 12th wk vs. AB 6th wk, P < 0.05). In addition, myocardial reverse remodeling was also associated with preserved ventriculoarterial coupling and increased mechanical efficiency (50.6 ± 2.8 vs. 38.9 ± 2.5%, debanded 12th wk vs. AB 12th wk, P < 0.05), indicating a complete functional and mechanoenergetic recovery. According to our best knowledge, this is the first study demonstrating that the regression of LVH is accompanied by maintained cardiac mechanoenergetics.

Oral treatment with a zinc complex of acetylsalicylic acid prevents diabetic cardiomyopathy in a rat model of type-2 diabetes: activation of the Akt pathway.

BACKGROUND: Type-2 diabetics have an increased risk of cardiomyopathy, and heart failure is a major cause of death among these patients. Growing evidence indicates that proinflammatory cytokines may induce the development of insulin resistance, and that anti-inflammatory medications may reverse this process. We investigated the effects of the oral administration of zinc and acetylsalicylic acid, in the form of bis(aspirinato)zinc(II)-complex Zn(ASA)2, on different aspects of cardiac damage in Zucker diabetic fatty (ZDF) rats, an experimental model of type-2 diabetic cardiomyopathy. METHODS: Nondiabetic control (ZL) and ZDF rats were treated orally with vehicle or Zn(ASA)2 for 24 days. At the age of 29-30 weeks, the electrical activities, left-ventricular functional parameters and left-ventricular wall thicknesses were assessed. Nitrotyrosine immunohistochemistry, TUNEL-assay, and hematoxylin-eosin staining were performed. The protein expression of the insulin-receptor and PI3K/AKT pathway were quantified by Western blot. RESULTS: Zn(ASA)2-treatment significantly decreased plasma glucose concentration in ZDF rats (39.0 ± 3.6 vs 49.4 ± 2.8 mM, P < 0.05) while serum insulin-levels were similar among the groups. Data from cardiac catheterization showed that Zn(ASA)2 normalized the increased left-ventricular diastolic stiffness (end-diastolic pressure-volume relationship: 0.064 ± 0.008 vs 0.084 ± 0.014 mmHg/µl; end-diastolic pressure: 6.5 ± 0.6 vs 7.9 ± 0.7 mmHg, P < 0.05). Furthermore, ECG-recordings revealed a restoration of prolonged QT-intervals (63 ± 3 vs 83 ± 4 ms, P < 0.05) with Zn(ASA)2. Left-ventricular wall thickness, assessed by echocardiography, did not differ among the groups. However histological examination revealed an increase in the cardiomyocytes' transverse cross-section area in ZDF compared to the ZL rats, which was significantly decreased after Zn(ASA)2-treatment. Additionally, a significant fibrotic remodeling was observed in the diabetic rats compared to ZL rats, and Zn(ASA)2-administered ZDF rats showed a similar collagen content as ZL animals. In diabetic hearts Zn(ASA)2 significantly decreased DNA-fragmentation, and nitro-oxidative stress, and up-regulated myocardial phosphorylated-AKT/AKT protein expression. Zn(ASA)2 reduced cardiomyocyte death in a cellular model of oxidative stress. Zn(ASA)2 had no effects on altered myocardial CD36, GLUT-4, and PI3K protein expression. CONCLUSIONS: We demonstrated that treatment of type-2 diabetic rats with Zn(ASA)2 reduced plasma glucose-levels and prevented diabetic cardiomyopathy. The increased myocardial AKT activation could, in part, help to explain the cardioprotective effects of Zn(ASA)2. The oral administration of Zn(ASA)2 may have therapeutic potential, aiming to prevent/treat cardiac complications in type-2 diabetic patients.

Dimethyloxalylglycine treatment of brain-dead donor rats improves both donor and graft left ventricular function after heart transplantation.

OBJECTIVE: Hypoxia inducible factor (HIF)-1 pathway signalling has a protective effect against ischemia/reperfusion injury. The prolyl-hydroxylase inhibitor dimethyloxalylglycine (DMOG) activates the HIF-1 pathway by stabilizing HIF-1α. In a rat model of brain death (BD)-associated donor heart dysfunction we tested the hypothesis that pre-treatment of brain-dead donors with DMOG would result in a better graft heart condition. METHODS: BD was induced in anesthetized Lewis rats by inflating a subdurally placed balloon catheter. Controls underwent sham operations. Then, rats were injected with an intravenous dose of DMOG (30 mg/kg) or an equal volume of physiologic saline. After 5 hours of BD or sham operation, hearts were perfused with a cold (4°C) preservation solution (Custodiol; Dr. Franz Köhler Chemie GmbH; Germany), explanted, stored at 4°C in Custodiol, and heterotopically transplanted. Graft function was evaluated 1.5 hours after transplantation. RESULTS: Compared with control, BD was associated with decreased left ventricular systolic and diastolic function. DMOG treatment after BD improved contractility (end-systolic pressure volume relationship E'max: 3.7 ± 0.6 vs 3.1 ± 0.5 mm Hg/µ1; p < 0.05) and left ventricular stiffness (end-diastolic pressure volume relationship: 0.13 ± 0.03 vs 0.31 ± 0.06 mm Hg/µ1; p < 0.05) 5 hours later compared with the brain-dead group. After heart transplantation, DMOG treatment of brain-dead donors significantly improved the altered systolic function and decreased inflammatory infiltration, cardiomyocyte necrosis, and DNA strand breakage. In addition, compared with the brain-dead group, DMOG treatment moderated the pro-apoptotic changes in the gene and protein expression. CONCLUSIONS: In a rat model of potential brain-dead heart donors, pre-treatment with DMOG resulted in improved early recovery of graft function after transplantation. These results support the hypothesis that activation of the HIF-1 pathway has a protective role against BD-associated cardiac dysfunction.

TiProtec preserves endothelial function in a rat model.

BACKGROUND: Coronary artery bypass surgery provides excellent patency rates; however, the early and/or late graft failure reduces the long-term benefit of myocardial revascularization. We investigated the effectiveness of generally used saline, Custodiol solutions and a new solution (TiProtec) at preserving endothelium after cold ischemia and warm reperfusion injury. MATERIALS AND METHODS: Aortic transplantations were performed in Lewis rats. Aortic arches were stored in saline, Custodiol, and TiProtec solutions for 2 h then were transplanted into the abdominal aorta. Two, 24 hours and 1 week after transplantation, the implanted grafts were harvested. Endothelium-dependent and -independent vasorelaxations were investigated in organ bath. DNA strand breaks were assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-method, messenger RNA expressions by quantitative real-time polymerase chain reaction, and the expression of CD-31 and alpha smooth muscle actin by immunochemistry. RESULTS: Severely impaired endothelial function and integrity of implanted aortic grafts were shown after 2 h in the saline, Custodiol group (maximal vasorelaxation to acetylcholine: control: 91 ± 2%, saline: 26 ± 5%, Custodiol: 24 ± 5%, CD-31-positive area control: 96 ± 2%, saline: 35 ± 13% Custodiol: 54 ± 5%, P < 0.05, respectively); however, a preserved endothelial function was observed in the TiProtec group when compared with the saline and Custodiol group (maximal vasorelaxation: 46 ± 7%, CD-31-positive area: 54 ± 10%, P < 0.05). After 1 wk, endothelial function was partially recovered in all groups; however, it was significantly better in the TiProtec group (maximal vasorelaxation to acetylcholine: saline: 42 ± 3%, Custodiol: 48 ± 3%, TiProtec: 56 ± 3%, CD-31-positive area: saline: 56 ± 5%, Custodiol: 54 ± 4%; TiProtec: 83 ± 6%, P < 0.05, respectively). In addition, messenger RNA levels of Bax, B-cell lymphoma-2, endothelial NOS, vascular endothelial growth factor 2, and caspase-3 were significantly altered in both groups. CONCLUSIONS: TiProtec appears to be superior for the preservation of endothelial- and smooth muscle cells of bypass graft after cold storage and warm reperfusion in our murine model.

Administration of zinc complex of acetylsalicylic acid after the onset of myocardial injury protects the heart by upregulation of antioxidant enzymes.

We recently demonstrated that the pre-treatment of rats with zinc and acetylsalicylic acid complex in the form of bis(aspirinato)zinc(II) [Zn(ASA)2] is superior to acetylsalicylic acid in protecting the heart from acute myocardial ischemia. Herein, we hypothesized that Zn(ASA)2 treatment after the onset of an acute myocardial injury could protect the heart. The rats were treated with a vehicle or Zn(ASA)2 after an isoproterenol injection. Isoproterenol-induced cardiac damage [inflammatory infiltration into myocardial tissue, DNA-strand breakage evidenced by TUNEL-assay, increased 11-dehydro thromboxane (TX)B2-levels, elevated ST-segment, widened QRS complex and prolonged QT-interval] was prevented by the Zn(ASA)2 treatment. In isoproterenol-treated rats, load-independent left ventricular contractility parameters were significantly improved after Zn(ASA)2. Furthermore, Zn(ASA)2 significantly increased the myocardial mRNA-expression of superoxide dismutase-1, glutathione peroxidase-4 and decreased the level of Na(+)/K(+)/ATPase. Postconditioning with Zn(ASA)2 protects the heart from acute myocardial ischemia. Its mechanisms of action might involve inhibition of pro-inflammatory prostanoids and upregulation of antioxidant enzymes.

Mild Type 2 Diabetes Mellitus Reduces the Susceptibility of the Heart to Ischemia/Reperfusion Injury: Identification of Underlying Gene Expression Changes.

Despite clinical studies indicating that diabetic hearts are more sensitive to ischemia/reperfusion injury, experimental data is contradictory. Although mild diabetes prior to ischemia/reperfusion may induce a myocardial adaptation, further research is still needed. Nondiabetic Wistar (W) and type 2 diabetic Goto-Kakizaki (GK) rats (16-week-old) underwent 45 min occlusion of the left anterior descending coronary artery and 24 h reperfusion. The plasma glucose level was significantly higher in diabetic rats compared to the nondiabetics. Diabetes mellitus was associated with ventricular hypertrophy and increased interstitial fibrosis. Inducing myocardial infarction increased the glucose levels in diabetic compared to nondiabetic rats. Furthermore, the infarct size was smaller in GK rats than in the control group. Systolic and diastolic functions were impaired in W + MI and did not reach statistical significance in GK + MI animals compared to the corresponding controls. Among the 125 genes surveyed, 35 genes showed a significant change in expression in GK + MI compared to W + MI rats. Short-term diabetes promotes compensatory mechanisms that may provide cardioprotection against ischemia/reperfusion injury, at least in part, by increased antioxidants and the upregulation of the prosurvival PI3K/Akt pathway, by the downregulation of apoptotic genes, proinflammatory cytokine TNF-α, profibrogenic TGF-ß, and hypertrophic marker α-actin-1.

Mild type 2 diabetes mellitus improves remote endothelial dysfunction after acute myocardial infarction.

AIMS: Myocardial infarction (MI) is a common cause of mortality in patients with diabetes mellitus (DM) and vascular dysfunction is a major component of diabetic cardiomyopathy. We investigated the systemic influence of acute MI on the diabetes-induced pathogenic changes in the rat aorta. METHODS: Nondiabetic Wistar (W) and type-2 diabetic Goto-Kakizaki (GK) rats underwent 45min of left anterior descending coronary artery occlusion followed by 24h of reperfusion. Isometric force was measured using organ bath. RESULTS: Plasma glucose-levels were significantly higher in diabetic rats (GK+sham: 13±2mM; GK+MI: 19±2mM) compared to nondiabetic rats (W+sham: 8±0mM; W+MI: 8±1mM). Acetylcholine-induced relaxation was significantly weaker in rings from W+MI and GK+MI rats compared to corresponding sham-operated animals. Myocardial reperfusion injury was smaller in GK+MI than W+MI rats, and the concentration-response curves to acetylcholine were significantly enhanced in rings from GK+MI than W+MI rats. Nevertheless, the relaxation response to acetylcholine was similar in W+sham and GK+sham. Densitometric analysis of bands for endothelial nitric oxide synthase showed a significant decrease in W+MI rats compared to W+sham and GK+sham animals. Aortas from both GK+sham and GK+MI rats showed impaired contractile responses to phenylephrine in comparison with the nondiabetics. CONCLUSIONS: For the first time we showed that short-term and mild type-2 DM improved remote endothelial dysfunction after reperfused acute MI.

Endothelial dysfunction of bypass graft: direct comparison of in vitro and in vivo models of ischemia-reperfusion injury.

BACKGROUND: Although, ischemia/reperfusion induced vascular dysfunction has been widely described, no comparative study of in vivo- and in vitro-models exist. In this study, we provide a direct comparison between models (A) ischemic storage and in-vitro reoxygenation (B) ischemic storage and in vitro reperfusion (C) ischemic storage and in-vivo reperfusion. METHODS AND RESULTS: Aortic arches from rats were stored for 2 hours in saline. Arches were then (A) in vitro reoxygenated (B) in vitro incubated in hypochlorite for 30 minutes (C) in vivo reperfused after heterotransplantation (2, 24 hours and 7 days reperfusion). Endothelium-dependent and independent vasorelaxations were assessed in organ bath. DNA strand breaks were assessed by TUNEL-method, mRNA expressions (caspase-3, bax, bcl-2, eNOS) by quantitative real-time PCR, proteins by Western blot analysis and the expression of CD-31 by immunochemistry. Endothelium-dependent maximal relaxation was drastically reduced in the in-vivo models compared to ischemic storage and in-vitro reperfusion group, and no difference showed between ischemic storage and control group. CD31-staining showed significantly lower endothelium surface ratio in-vivo, which correlated with TUNEL-positive ratio. Increased mRNA and protein levels of pro- and anti-apoptotic gens indicated a significantly higher damage in the in-vivo models. CONCLUSION: Even short-period of ischemia induces severe endothelial damage (in-vivo reperfusion model). In-vitro models of ischemia-reperfusion injury can be limitedly suited for reliable investigations. Time course of endothelial stunning is also described.

Graft preservation with heparinized blood/saline solution induces severe graft dysfunction.

OBJECTIVES: Vascular grafts are often stored in cold physiological saline/heparinized blood preservation solution. Until now, only in vitro studies investigated the effect of the aforementioned preservation solutions on endothelial function. The main goal of our study was to compare the storage effect of physiological saline and heparinized blood after short-time cold storage and warm reperfusion in a rat model of aortic transplantation. METHODS: Aortic abdominal transplantations (n = 6-8/group) were performed in Lewis rats. The donor aortic arches were placed in cold physiological saline and heparinized blood solutions and stored for 2 h. After the 2 h ischaemia, the aortic arches were transplanted into the abdominal aorta of the recipient. Two, 24 h or 1 week after transplantation, implanted grafts were harvested. Endothelium-dependent (acetylcholine) and -independent (sodium nitroprusside) vasorelaxation were investigated in organ bath experiments. DNA strand breaks were assessed by transferase-mediated dUTP nick-end labelling-method and mRNA expression by quantitative real-time polymerase chain reaction. In addition, the expression of CD-31 was also investigated by immunochemistry. RESULTS: Severely impaired endothelial function and integrity of grafts were shown after 2 and 24 h reperfusion in both groups (maximal vasorelaxation control: 94 ± 1%, heparinized blood: 27 ± 4 and 17 ± 3%, saline 34 ± 5% and 28 ± 5%; CD-31 positive area control: 96 ± 1% blood: 38 ± 8% and 41 ± 6%, saline: 35 ± 12% and 41 ± 7%, respectively P < 0.05). After 1 week, endothelial function and integrity were partially recovered (maximal vasorelaxation: heparinized blood: 46 ± 4%, saline: 46 ± 2%, CD-31 positive area blood: 35 ± 4%; saline: 56 ± 5%, P < 0.05). In addition, mRNA levels of Bax, Bcl-2 and caspase-3 were significantly altered and DNA stand breaks were observed. CONCLUSIONS: Storage with the generally used physiological saline and heparinized blood solutions is unable to protect the endothelium against cold ischaemia and warm reperfusion injury. A similar weak preservation effect was observed.

Superiority of zinc complex of acetylsalicylic acid to acetylsalicylic acid in preventing postischemic myocardial dysfunction.

The pathophysiology of ischemic myocardial injury involves cellular events, reactive oxygen species, and an inflammatory reaction cascade. The zinc complex of acetylsalicylic acid (Zn(ASA)2) has been found to possess higher anti-inflammatory and lower ulcerogenic activities than acetylsalicylic acid (ASA). Herein, we studied the effects of both ASA and Zn(ASA)2 against acute myocardial ischemia. Rats were pretreated with ASA (75 mg/kg) or Zn(ASA)2 (100 mg/kg) orally for five consecutive days. Isoproterenol (85 mg/kg, subcutaneously [s.c.]) was applied to produce myocardial infarction. After 17-22 h, animals were anesthetized with sodium pentobarbital (60 mg/kg, intraperitoneally [i.p.]) and both electrical and mechanical parameters of cardiac function were evaluated in vivo. Myocardial histological and gene expression analyses were performed. In isoproterenol-treated rats, Zn(ASA)2 treatment normalized significantly impaired left-ventricular contractility index (Emax 2.6 ± 0.7 mmHg/µL vs. 4.6 ± 0.5 mmHg/µL, P < 0.05), increased stroke volume (30 ± 3 µL vs. 50 ± 6 µL, P < 0.05), decreased systemic vascular resistance (7.2 ± 0.7 mmHg/min/mL vs. 4.2 ± 0.5 mmHg/min/mL, P < 0.05) and reduced inflammatory infiltrate into the myocardial tissues. ECG revealed a restoration of elevated ST-segment (0.21 ± 0.03 mV vs. 0.09 ± 0.02 mV, P < 0.05) and prolonged QT-interval (79.2 ± 3.2 ms vs. 69.5 ± 2.5 ms, P < 0.05) by Zn(ASA)2. ASA treatment did not result in an improvement of these parameters. Additionally, Zn(ASA)2 significantly increased the mRNA-expression of superoxide dismutase 1 (+73 ± 15%), glutathione peroxidase 4 (+44 ± 12%), and transforming growth factor (TGF)-ß1 (+102 ± 22%). In conclusion, our data demonstrate that oral administration of zinc and ASA in the form of bis(aspirinato)zinc(II) complex is superior to ASA in preventing electrical, mechanical, and histological changes after acute myocardial ischemia. The induction of antioxidant enzymes and the anti-inflammatory cytokine TGF-ß1 may play a pivotal role in the mechanism of action of Zn(ASA)2.

Transplantation of donor hearts after circulatory or brain death in a rat model.

BACKGROUND: Heart transplantation represents the only curative treatment for end-stage heart failure. Presently, the donor pool is restricted to brain-dead donors. Based on the lack of suitable donors and the increasing number of patients, we investigated some molecular pathomechanisms of the potential use of hearts after circulatory determination of death (DCDD) in transplantation. MATERIALS AND METHODS: Rats were either maintained brain death for 5 h by inflation of a subdurally placed balloon catheter (n = 6) or subjected to cardiac arrest by exsanguinations (n = 6). Additionally, a control group was used (n = 9). Then the hearts were perfused with a cold preservation solution (Custodiol), explanted, stored at 4°C in Custodiol, and heterotopically transplanted. RESULTS: Brain death was associated with decreased left-ventricular contractility (dP/dtmax: 4895 ± 505 versus 8037 ± 565 mm Hg/s; ejection fraction: 27 ± 5 versus 44 ± 5%; Emax: 2.2 ± 0.3 versus 4.2 ± 0.3 mm Hg/µL; preload recruitable stroke work: 59 ± 5 versus 96 ± 6 mm Hg; 5 h after brain death versus before brain death; P < 0.05) and impaired cardiac relaxation (dP/dtmin: -4734 ± 575 versus -9404 ± 550 mm Hg/s and prolonged Tau, P < 0.05) compared with controls. After transplantation, significantly decreased systolic function and prolonged Tau were observed in brain-dead and DCDD groups compared with those in controls. Tumor necrosis factor-alpha, cyclooxygenase-2, nuclear factor-κB, inducible-NOS, and caspase-3 messenger RNA and protein-levels were significantly increased in the brain-dead compared with both control and DCDD groups. Additionally, marked myocardial inflammatory cell infiltration, edema, necrosis, and DNA-strand breaks were observed in the brain-dead group. CONCLUSIONS: Our results show that despite the similar functional outcome in DCDD and brain-dead groups, brain-dead hearts showed marked myocardial inflammatory cell infiltration, edema, necrosis, DNA-strand breaks, and increased transcriptional and posttranscriptional expression for markers of apoptosis and inflammatory signaling pathways.

Short- and long-term effects of brain death on post-transplant graft function in a rodent model.

OBJECTIVES: Heart transplantation has become the most effective treatment for end-stage heart failure. Donors after brain death (BD) are currently the only reliable source for cardiac transplants. However, haemodynamic instability and cardiac dysfunction have been demonstrated in brain-dead donors and this could therefore also affect post-transplant graft function. We studied the effects of BD on cardiac function and its short-term (1 h) or long-term (5 h) impacts on graft function. METHODS: In Lewis rats, BD was induced by inflation of a subdurally placed balloon catheter (n = 7). Sham-operated rats served as controls (n = 9). We continuously assessed cardiac function by left ventricular (LV) pressure-volume analysis. Then, 1 or 5 h after BD or sham operation, hearts were perfused with a cold preservation solution (Custodiol), then explanted, stored at 4°C in Custodiol and heterotopically transplanted. We evaluated graft function 1.5 h after transplantation. RESULTS: BD was associated with decreased left ventricular contractility (ejection fraction: 37 ± 6 vs 57 ± 5%; maximum rate of rise of LV pressure dP/dtmax: 4770 ± 197 vs 7604 ± 348 mmHg/s; dP/dtmax-end-diastolic volume: 60 ± 7 vs 74 ± 2 mmHg/s; slope Emax of the end-systolic pressure-volume relationship: 2.4 ± 0.1 vs 4.4 ± 0.3 mmHg/µl; preload recruitable stroke work: 47 ± 9 vs 78 ± 3 mmHg; P <0.05) and relaxation (maximum rate of fall of left ventricular pressure dP/dtmin: -6638 ± 722 vs -11 285 ± 539 mmHg/s; time constant of left ventricular pressure decay Tau: 12.6 ± 0.7 vs 10.5 ± 0.4 ms; end-diastolic pressure-volume relationship: 0.22 ± 0.05 vs 0.09 ± 0.03 mmHg/µl, P <0.05) 45 min after its initiation and for the rest of 5 h compared with controls. Moreover, after transplantation, graft systolic and diastolic functions were impaired in the 5-h brain-dead group, while they were identical in the 1-h brain-dead group compared with the corresponding controls. CONCLUSIONS: We established a well-characterized in vivo rat model to examine the influence of BD on cardiac function using a miniaturized technology for pressure-volume analysis. These results demonstrate that impaired donor cardiac function after short-term BD is reversible after transplantation and long-term BD renders hearts more susceptible to ischaemia/reperfusion injury.

TiO2-Mediated Photocatalytic Mineralization of a Non-Ionic Detergent: Comparison and Combination with Other Advanced Oxidation Procedures.

Triton X-100 is one of the most widely-applied man-made non-ionic surfactants. This detergent can hardly be degraded by biological treatment. Hence, a more efficient degradation method is indispensable for the total mineralization of this pollutant. Application of heterogeneous photocatalysis based on a TiO2 suspension is a possible solution. Its efficiency may be improved by the addition of various reagents. We have thoroughly examined the photocatalytic degradation of Triton X-100 under various circumstances. For comparison, the efficiencies of ozonation and treatment with peroxydisulfate were also determined under the same conditions. Besides, the combination of these advanced oxidation procedures (AOPs) were also studied. The mineralization of this surfactant was monitored by following the TOC and pH values, as well as the absorption and emission spectra of the reaction mixture. An ultra-high-performance liquid chromatography (UHPLC) method was developed and optimized for monitoring the degradation of Triton X-100. Intermediates were also detected by GC-MS analysis and followed during the photocatalysis, contributing to the elucidation of the degradation mechanism. This non-ionic surfactant could be efficiently degraded by TiO2-mediated heterogeneous photocatalysis. However, surprisingly, its combination with the AOPs applied in this study did not enhance the rate of the mineralization. Moreover, the presence of persulfate hindered the photocatalytic degradation.

Bis (aspirinato) zinc (II) complex successfully inhibits carotid arterial neointima formation after balloon-injury in rats.

PURPOSE: Neointima formation following angioplasty is a serious consequence of endothelial damage in arteries. Inflammatory mediators and lack of endothelial regulatory mechanisms lead to migration and proliferation of smooth-muscle cells and thus to restenosis. This study examines the effect of the novel bis (aspirinato) zinc (II) complex on neointima formation in a rat model of carotid balloon-injury. METHODS: Rats underwent balloon-injury of the right common carotid artery, then received PEG400 vehicle (untreated-group), acetylsalicylic-acid (ASA-group), zinc-chloride (Zn-group) and bis (aspirinato) zinc (II) complex (Zn(ASA) 2-group) orally for 18 consecutive days. From harvested carotid arteries, histology, immunohistochemistry and mRNA expression analysis were performed. RESULTS: Compared to the untreated-group, Zn (ASA) 2-treatment significantly lowered stenosis ratio (54.0 ± 5.8% to 25.5 ± 3.9%) and reduced neointima/media ratio (1.5 ± 0.2 to 0.5 ± 0.1). Significantly higher alpha smooth muscle actin mRNA and protein expression were measured after Zn (ASA)2 and Zn-treatment in comparison with the untreated and ASA-groups while the expression of matrix-metalloproteinase-9 was significantly higher in these groups compared to Zn (ASA)2. The presence of collagen in media was significantly decreased in all treated groups. mRNA expressions of nuclear factor kappa-b, transforming growth-factor-ß and proliferating cell nuclear antigen were significantly down-regulated, whereas a20 was up-regulated by Zn (ASA)2 treatment compared to the untreated and ASA-groups. CONCLUSION: This study proves the effectivity of the novel bis (aspirinato) zinc complex in reducing neointima formation and restenosis after balloon-injury and supports the hypothesis that inhibition of smooth-muscle transformation/proliferation plays a key role in the prevention of restenosis.

Provocation of an autoimmune response to cardiac voltage-gated sodium channel NaV1.5 induces cardiac conduction defects in rats.

OBJECTIVES: This study sought to test the hypothesis that inducing an autoimmune response against the cardiac sodium channel (NaV1.5) induces arrhythmias. BACKGROUND: Sporadic evidence supports the concept that autoantibodies may cause cardiac arrhythmias but substantial experimental investigations using in vivo models have been lacking to date. The NaV1.5 is essential for cardiac impulse propagation and its dysfunction has been linked to conduction disease. METHODS: Rats were immunized with a peptide sequence derived from the third extracellular loop of the first domain of NaV1.5. After 28 days, we evaluated in vivo both the electrical and mechanical parameters of cardiac function. Histopathology, myocardial gene and protein expression were assessed. Whole-cell patch-clamp was used to measure sodium current (INa) density in isolated cardiomyocytes. RESULTS: NaV1.5-immunized rats had high titers of autoantibodies against NaV1.5. On ECG recording, NaV1.5-immunized animals showed significantly prolonged PR-intervals. During Holter ECG-monitoring we observed repeated prolonged episodes of third-degree atrioventricular and sinoatrial block in every NaV1.5-immunized animal, but not in controls. Immunization had no effect on cardiac function. In comparison to controls, myocardial NaV1.5 mRNA and protein levels were decreased in immunized rats. INa density was reduced in cardiomyocytes incubated with sera from NaV1.5-immunized rats and from patients with idiopathic atrioventricular block (AVB) in comparison to sera from respective controls. In patients with idiopathic AVB, we observed autoantibodies against NaV1.5 that were absent in sera from healthy controls. CONCLUSIONS: Provocation of an autoimmune response against NaV1.5 induces conductance defects probably caused by a reduced expression level and an inhibition of NaV1.5 by autoantibodies, resulting in decreased INa.

Q50, an iron-chelating and zinc-complexing agent, improves cardiac function in rat models of ischemia/reperfusion-induced myocardial injury.

BACKGROUND: Reperfusion of ischemic myocardium may contribute to substantial cardiac tissue damage, but the addition of iron chelators, zinc or zinc complexes has been shown to prevent heart from reperfusion injury. We investigated the possible beneficial effects of an iron-chelating and zinc-complexing agent, Q50, in rat models of ischemia/reperfusion (I/R)-induced myocardial infarction and on global reversible myocardial I/R injury after heart transplantation. METHODS AND RESULTS: Rats underwent 45-min myocardial ischemia by left anterior descending coronary artery ligation followed by 24h reperfusion. Vehicle or Q50 (10 mg/kg, IV) were given 5 min before reperfusion. In a heart transplantation model, donor rats received vehicle or Q50 (30 mg/kg, IV) 1h before the onset of ischemia. In myocardial infarcted rats, increased left ventricular end-systolic and end-diastolic volumes were significantly decreased by Q50 post treatment as compared with the sham group. Moreover, in I/R rat hearts, the decreased dP/dtmax and load-independent contractility parameters were significantly increased after Q50. However, Q50 treatment did not reduce infarct size or have any effect on increased plasma cardiac troponin-T-levels. In the rat model of heart transplantation, 1h after reperfusion, decreased left ventricular systolic pressure, dP/dt(max), dP/dt(min) and myocardial ATP content were significantly increased and myocardial protein expression of superoxide dismutase-1 was upregulated after Q50 treatment. CONCLUSIONS: In 2 experimental models of I/R, administration of Q50 improved myocardial function. Its mechanisms of action implicate in part the restoration of myocardial high-energy phosphates and upregulation of antioxidant enzymes.