Retraction: On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre.

Retraction of 'On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre' by Nora Bergmann et al., Phys. Chem. Chem. Phys., 2010, 12, 4827-4832.

Atrioesophageal fistula following ablation procedures for atrial fibrillation: systematic review of case reports.

BACKGROUND: Atrioesophageal fistula (AEF) is a rare but serious adverse event of atrial fibrillation (AF) ablation. OBJECTIVE: To identify the clinical characteristics of AEF following ablation procedures for AF and determine the associated mortality. METHODS: A systematic review of observational cases of AEF following ablation procedures for AF was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement protocol. RESULTS: 53 cases were identified. Mean age was 54±13 years; 73% (39/53) of cases occurred in males. Mean interval between procedure and presentation was 20±12 days, ranging from 2 to 60 days. AEF was observed in 12 patients who underwent surgical radiofrequency ablation (RFA) and in 41 patients with percutaneous RFA. Fever was the most common presenting symptom (n=44) followed by neurological deficits (n=27) and haematemesis (n=19). CT of the chest (n=27) was the preferred diagnostic test. Patients who did not receive a primary esophageal repair were more likely to have a deadly outcome (34% vs 83%; p<0.05). No difference in mortality rate was found between patients who underwent surgical RFA when compared with percutaneous RFA (58% vs 56%; p=0.579). No association was found between onset of symptoms and mortality (19±10 vs 23±14 days; p=0.355). CONCLUSIONS: AEF following ablation procedures for AF is a serious complication with high mortality rates. Presenting symptoms most often include a triad of fever, neurological deficit and/or haematemesis within 60 days of procedure. The preferred diagnostic test is CT of the chest. The treatments of choice is surgical repair.

Assistance of the iron porphyrin ligands to the binding interaction between the Fe center and small molecules in solution.

Solute-solvent electronic structure interactions of iron porphyrin at very low concentration in dichloromethane (CH2Cl2) liquid solution are reported. Two iron porphyrin complexes are investigated here-iron octaethylporphyrin chloride (FeOEP-Cl) and iron tetraphenylporphyrin chloride (FeTPP-Cl)-using X-ray absorption and emission spectroscopy at the Fe L2,3 edge, and spectra are interpreted with the help of density functional theory/restricted open-shell configuration interaction singles (DFT/ROCIS) calculations. It is argued that the Fe center of FeOEP-Cl is more capable of binding small solvent molecules, exemplified here for Cl2CH2, than FeTPP-Cl in solution. The proposed binding mechanism is through the assistance of the dipole interaction between the porphyrin-ligand system and the solvent molecule, in a situation where the ligand structure and arrangement maximize the binding interactions. Our studies demonstrate that even small ligands, depending on their structure and arrangement, can have considerable effects on porphyrin's metal center chemistry in liquid solution.

Ligand discrimination of myoglobin in solution: an iron L-edge X-ray absorption study of the active centre.

Iron L-edge X-ray absorption spectra of the active centre of myoglobin in the met-form, in the reduced form and upon ligation to O2, CO, NO and CN are presented. The strength of ligation with the iron centre is finger-printed through the variation of the L3 : L2 intensity ratio. Charge Transfer Multiplet calculations are performed and give qualitative information about oxidation states as well as charge transfer.

Implementing a pathway for the management of acute coronary syndrome leads to improved compliance with guidelines and a decrease in angina symptoms.

We describe our experience with the Advanced Cardiac Admission Program (ACAP) at our institution. The ACAP program is a hospital-wide implementation of critical pathways-based management of all cardiac patients. Data review of patients admitted for acute coronary syndromes from the ACAP-PAIN database and a comparative study of outcomes before and after implementation of the pathways-based assessment and treatment protocols. In the pre-ACAP and post-ACAP patient groups, antiplatelet use at admission improved from 50% to 75% (p<.01), ACE-I use improved from 32% to 54% (p<.0001), statins use increased from 35% to 62% (p<.0001), and smoking cessation awareness increased from 15% to 86% (p<.0001). At 1-year follow-up, 84% of patients with CAD were treated with statins, and 47% had LDL cholesterol <100 mg/dL, compared with 20% and 9%, respectively, with conventional treatment before ACAP implementation (p<.0001). Recurrent angina symptoms and nonfatal myocardial infarction rates decreased from 28.5% to 13% (p = .02), and 15% to 5% (p = 0.03), respectively. Pathway-based programs like ACAP significantly enhance administration of guidelines-based cardioprotective medications both during hospital stay and at 1-year follow-up.

Malnutrition as assessed by nutritional risk index is associated with worse outcome in patients admitted with acute decompensated heart failure: an ACAP-HF data analysis.

Malnutrition is common at hospital admission and tends to worsen during hospitalization. This controlled population study aimed to determine if serum albumin or moderate and severe nutritional depletion by Nutritional Risk Index (NRI) at hospital admission are associated with increased length of hospital stay (LOS) in patients admitted with acute decompensated heart failure (ADHF). Serum albumin levels and lymphocyte counts were retrospectively determined at hospital admission in 1740 consecutive patients admitted with primary and secondary diagnosis of ADHF. The Nutrition Risk Score (NRI) developed originally in AIDS and cancer populations was derived from the serum albumin concentration and the ratio of actual to usual weight, as follows: NRI = (1.519 × serum albumin, g/dL) + {41.7 × present weight (kg)/ideal body weight(kg)}. Patients were classified into four groups as no, mild, moderate or severe risk by NRI. Multiple logistic regressions were used to determine the association between nutritional risk category and LOS.Three hundred and eighty-one patients (34%) were at moderate or severe nutritional risk by NRI score. This cohort had lower BMI (24 ± 5.6 kg/m(2)), albumin (2.8±0.5 g/dL), mean NRI (73.5±9) and lower eGFR (50±33 mL/min per 1.73 m(2)). NRI for this cohort, adjusted for age, was associated with LOS of 10.1 days. Using the Multiple Logistic regression module, NRI was the strongest predictor for LOS (OR 1.7, 95% CI: 1.58-1.9; P=0.005), followed by TIMI Risk Score [TRS] (OR 1.33, 95% CI: 1.03-1.71; P=0.02) and the presence of coronary artery disease (OR 2.29, 95%CI: 1.03-5.1; P=0.04). Moderate and severe NRI score was associated with higher readmission and death rates as compared to the other two groups.Nutritional depletion as assessed by Nutritional Risk Index is associated with worse outcome in patients admitted with ADHF. Therefore; we recommend adding NRI to further risk stratify these patients.

On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre.

Catalase and methaemoglobin have very similar haem groups, which are both ferric, yet catalase decomposes hydrogen peroxide to water and oxygen very efficiently, while methaemoglobin does not. Structural studies have attributed this behaviour to their different distal environments. Here we present Fe L(2,3)-edge X-ray absorption spectra of these proteins in physiological solutions, which reveal clear differences in their electronic structures, in that pi back-donation of the Fe atom occurs in catalase, which confers on it a partial ferryl (Fe(4+)) character, while this is not the case in methaemoglobin. The origin of the Fe(4+) character stems from the proximal tyrosine residue. We also find that both systems are in a high spin state. Temperature effects influence the spectra of catalase only weakly, in agreement with previous studies of its chemical activity. We conclude that the high activity of catalase is not only determined by its distal environment but also by its partial ferryl character.

Strategies for the prevention and treatment of sudden cardiac death.

Cardiovascular diseases account for 40% of all deaths in the West. Sudden cardiac death (SCD) is a major health problem affecting over 300,000 patients annually in the United States alone. Presence of coronary artery disease (CAD), usually in the setting of diminished left ventricular ejection fraction, is still the single major risk factor for SCD. Additionally, acute myocardial ischemia, structural cardiac defects, anomalous coronary arteries, cardiomyopathies, genetic mutations, and ventricular arrhythmias are all attributed to SCD, demonstrating the perplexity of this condition. With the recent advancements in cardiovascular medicine, the incidence of SCD is expected to increase steeply as the prevalence of CAD and heart failure is uprising in general population. Considering SCD, the major challenge confronting contemporary cardiology, multiple strategies for prevention against SCD have been developed. ß-blockers have been shown to reduce the risk of SCD, whereas implantable cardioverter-defibrillator devices are found to be effective at terminating the malignant arrhythmias. In recent years, multiple clinical trials were carried out to identify patients who may benefit from preventive intervention, including medical therapy and automatic cardioverter-defibrillator implantations. This review article provides insight into the advanced strategies for the prevention and treatment of SCD based on the data available in medical literature to date.

Solvent effect of alcohols at the L-edge of iron in solution: X-ray absorption and multiplet calculations.

The local electronic structure of Fe(III) and Fe(II) ions in different alcohol solutions (methanol, ethanol, propan-1-ol) is investigated by means of soft X-ray absorption spectroscopy at the iron L 2,3-edge. The experimental spectra are compared with ligand field multiplet simulations. The solvated Fe(III) complex is found to exhibit octahedral symmetry, while a tetragonal symmetry is observed for Fe(II). A decrease in the solvent polarity increases the charge transfer from the oxygen of the alcohol to the iron ions. This conclusion is supported by Hartree-Fock calculations of the Mulliken charge distribution on the alcohols. A larger charge transfer is further observed from the solvent to Fe(III) compared to Fe(II), which is connected to the higher positive charge state of the former. Finally, iron ions in solution are found to prefer the high-spin configuration irrespective of their oxidation state.

Electronic rearrangement upon the hydrolyzation of aqueous formaldehyde studied by core-electron spectroscopies.

We have combined near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) to study the electronic rearrangement associated with the hydrolyzation of formaldehyde to methanediol in aqueous solution. The spectra are contrasted against those of aqueous formamide and urea, which are structurally similar but do not undergo hydrolysis in solution. We have recently demonstrated that the hydrolyzation of formaldehyde is manifested in the oxygen 1s NEXAFS spectrum by the disappearance of the oxygen 1s --> pi* absorption line. This is a characteristic signature that the C=O double bond has been broken. In the present study we extend our investigation to include carbon 1s NEXAFS and XPS spectra of the three solutions. The carbon NEXAFS spectra show the C 1s --> pi* absorption line for each solute except for formaldehyde. Moreover, the carbon 1s photoelectron spectra exhibit a single peak for each solute. These observations point to a near complete hydrolyzation of formaldehyde, whereas formamide and urea remain intact in the solution. The analysis is further supported by density functional theory (DFT) calculations, showing a C 1s chemical shift of approximately 1.0 eV between hydrolyzed and nonhydrolyzed forms, which would give distinguishable features in the photoemission spectrum, if coexisting forms were present in the solutions.

Novel approach in radionuclide tumor therapy: dose enhancement by high Z-element contrast agents.

PURPOSE: The aim of this study was to first calculate the dose-enhancement effect from internalized radiation by the presence of exogenous contrast media using Monte Carlo simulations, and then provide in vitro proof-of-concept for this novel method of radiation-dose enhancement. MATERIALS AND METHODS: The Monte Carlo program EGSnrc (Electron Gamma Shower) was used to simulate the interaction of internalizing radiation with iodine (I) or gadolinium (Gd) containing contrast media. Experimentally, the doseenhancement effect induced by I or Gd was evaluated in cell culture assays using internalizing peptides chelated with beta- emitting radionuclides and clinically available contrast media. RESULTS: Monte Carlo simulations predicted significant enhancement (approximately 70-340%) of radiation dose in the presence of high Zelement contrast media. This enhancement is radiation and Z-element dependent. Calculations showed that in the presence of contrast media, low-energy radionuclides favor localization of secondary particles, whereas higher energy beta- emitters localize radiation by reducing the pathway of the primary beta-particle. The dose enhancement was verified in vitro in two cell lines. CONCLUSIONS: Monte Carlo simulations in parallel with in vitro studies provide proof-of-principle for dose enhancement that occurs when utilizing an internalized source of radiation followed by the addition of exogenous contrast media. This dose enhancement is both radiation and Z-element dependent.