Intracoronary electrocardiogram detects coronary microvascular dysfunction and ischemia in patients with no obstructive coronary arteries disease.

BACKGROUND: Coronary microvascular dysfunction (CMD) is the leading cause of ischemia with no obstructive coronary arteries disease (INOCA) disease. Diagnosis of CMD relies on surrogate physiological indices without objective proof of ischemia. OBJECTIVES: Intracoronary electrocardiogram (icECG) derived hyperemic indices may accurately and objectively detect CMD and reversible ischemia in related territory. METHODS: INOCA patients with proven ischemia by myocardial perfusion scan (MPS) and completely normal coronary arteries underwent simultaneous intracoronary electrophysiological (icECG) and physiological (intracoronary Doppler) assessment in all 3 coronary arteries during rest and under adenosine induced hyperemia. RESULTS: Sixty vessels in 21 patients were included in the final analysis. All patients had at least one vessel with abnormal CFR. 41 vessels had CMD (CFR < 2.5), of which 26 had increased microvascular resistance (structural CMD, HMR > 1.9 mmHg.cm-1.s) and 15 vessels had CMD (CFR < 2.5) with normal microvascular resistance (functional CMD, HMR <= 1.9 mmHg.cm-1.s). Only one-third of the patients (n = 7) had impaired CFR < 2.5 in all 3 epicardial arteries. Absolute ST shift between hyperemia and rest (∆ST) has shown the best diagnostic performance for ischemia (cut-off 0.10 mV, sensitivity: 95%, specificity: 72%, accuracy: 80%, AUC: 0.860) outperforming physiological indices (CFR: 0.623 and HMR: 0.653 DeLong's test P = .0002). CONCLUSIONS: In INOCA patients, CMD involves coronary artery territories heterogeneously. icECG can accurately detect CMD causing perfusion abnormalities in patients with INOCA outperforming physiological CMD markers, by demonstrating actual ischemia instead of predicting the likelihood of inducible ischemia based on violated surrogate thresholds of blunted flow reserve or increased minimum microvascular resistance. CONDENSED ABSTRACT: In 21 INOCA patients with coronary microvascular dysfunction (CMD) and myocardial perfusion scan proved ischemia, hyperemic indices of intracoronary electrocardiogram (icECG) have accurately detected vessel-specific CMD and resulting perfusion abnormalities & ischemia, outperforming invasive hemodynamic indices. Absolute ST shift between hyperemia and rest (∆ST) has shown the best classification performance for ischemia in no Obstructive Coronary Arteries (AUC: 0.860) outperforming Doppler derived CMD indices (CFR: 0.623 and HMR: 0.653 DeLong's test P = .0002).icECG can be used to diagnose CMD causing perfusion defects by demonstrating actual reversible ischemia at vessel-level during the initial CAG session, obviating the need for further costly ischemia tests. CLINICALTRIALS: GOV: NCT05471739.

Coronary microcirculation in nonculprit vessel territory in reperfused acute myocardial infarction.

BACKGROUND: There is an ongoing debate on the extension of reperfusion-related microvascular damage (MVD) throughout the remote noninfarcted myocardial regions in patients with ST-elevation myocardial infarction (STEMI) that undergo primary percutaneous intervention (pPCI). The aim of this study was to elucidate the impact of reperfusion on remote microcirculatory territory by analyzing hemodynamic alterations in the nonculprit-vessel in relation to reperfusion. METHODS: A total of 20 patients with STEMI undergoing pPCI were included. Peri-reperfusion temporal changes in hemodynamic parameters were obtained in angiographically normal nonculprit vessels before and 1-h after reopening of the culprit vessel. Intracoronary pressure and flow velocity data were compared using pairwise analyses (before and 1-h after reperfusion). RESULTS: In the non-culprit vessel, compared to the pre-reperfusion state, mean resting average peak velocity (33.4 ± 9.4 to 25.0 ± 4.9 cm/s, P < 0.001) and mean hyperemic average peak velocity (53.5 ± 14.4 to 42.1 ± 10.66 cm/s, P = 0.001) significantly decreased; whereas baseline (3.2 ± 1.0 to 4.0 ± 1.0 mmHg.cm-1.s, P < 0.001) and hyperemic microvascular resistance (HMR) (1.9 ± 0.6 to 2.4 ± 0.7 mmHg.cm-1.s, P < 0.001) and mean zero flow pressure (Pzf) values (32.5 ± 6.9 to 37.6 ± 8.3 mmHg, P = 0.003) significantly increased 1-h after reperfusion. In particular, the magnitude of changes in HMR and Pzf values following reperfusion were more prominent in patients with larger infarct size and with higher extent of MVD in the culprit vessel territory. CONCLUSION: Reperfusion-related microvascular injury extends to involve remote myocardial territory in relation to the magnitude of the adjacent infarction and infarct-zone MVD. (GUARD Clinical TrialsNCT02732080).

The Interplay between Features of Plaque Vulnerability and Hemodynamic Relevance of Coronary Artery Stenoses.

Fractional flow reserve (FFR) may not be immune from hemodynamic perturbations caused by both vessel and lesion related factors. The aim of this study was to investigate the impact of plaque- and vessel wall-related features of vulnerability on the hemodynamic effect of intermediate coronary stenoses. Methods and Results: In this cross-sectional study, patients referred to catheterization laboratory for clinically indicated coronary angiography were prospectively screened for angiographically intermediate stenosis (50-80%). Seventy lesions from 60 patients were evaluated. Mean angiographic stenosis was 62.1 ± 16.3%. After having performed FFR assessment, intravascular ultrasound (IVUS) was performed over the FFR wire. Virtual histology IVUS was used to identify the plaque components and thin cap fibroatheroma (TCFA). TCFA was significantly more frequent (65 vs. 38%, p = 0.026), and necrotic core volume (26.15 ± 14.22 vs. 16.21 ± 8.93 mm3, p = 0.04) was significantly larger in the positively remodeled than non-remodeled vessels. Remodeling index correlated with necrotic core volume (r = 0.396, p = 0.001) and with FFR (r = -0. 419, p = 0.001). With respect to plaque components, only necrotic core area (r = -0.262, p = 0.038) and necrotic core volume (r = -0.272, p = 0.024) were independently associated with FFR. In the multivariable model, presence of TCFA was independently associated with significantly lower mean FFR value as compared to absence of TCFA (adjusted, 0.71 vs. 0.78, p = 0.034). Conclusion: The current study demonstrated that for a given stenosis geometry, features of plaque vulnerability such as necrotic core volume, TCFA, and positive remodeling may influence the hemodynamic relevance of intermediate coronary stenoses.

Validation of the adjusted global antiphospholipid syndrome score in a single centre cohort of APS patients from Turkey.

The adjusted global antiphospholipid syndrome score (aGAPSS) is a recently developed thrombotic risk assessment score that considers the antiphospholipid antibody (aPL) profile and conventional cardiovascular risk factors. In this retrospective study, we aimed to evaluate the validity of the aGAPSS in predicting clinical manifestations (criteria and extra-criteria) of antiphospholipid syndrome (APS) in a single centre cohort of patients. Ninety-eight patients with APS ± systemic lupus erythematosus (SLE) were classified according to clinical manifestations as vascular thrombosis (VT), pregnancy morbidity (PM) or both (VT + PM). The aGAPSS was calculated for each patient as previously defined. Mean aGAPSS of the cohort was calculated as 10.2 ± 3.8. Significantly higher aGAPSS values were seen in VT (n = 58) and VT + PM (n = 29) groups when compared to PM (n = 11) group (10.6 ± 3.7 vs 7.4 ± 2.9, P = 0.005; 10.7 ± 4 vs 7.4 ± 2.9, P = 0.008, respectively), mainly due to lower frequencies of cardiovascular risk factors in PM. Higher aGAPPS values were also associated with recurrent thrombosis (11.6 ± 3.7 vs 9.9 ± 3.6, P = 0.04). Regarding extra-criteria manifestations, patients with livedo reticularis (n = 11) and APS nephropathy (n = 9) had significantly higher aGAPSS values (12.9 ± 3.4 vs 9.9 ± 3.7, P = 0.02; 12.4 ± 2.9 vs 10 ± 3.8, P = 0.04, respectively). The computed AUC demonstrated that aGAPSS values ≥10 had the best diagnostic accuracy for thrombosis. Our results suggest that patients with higher aGAPSS values are at higher risk for developing vascular thrombosis (either first event or recurrence) and extra-criteria manifestations, especially livedo reticularis and APS nephropathy.

Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI.

BACKGROUND: Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR. METHODS: We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk. RESULTS: At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001). CONCLUSIONS: Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .).

Redox induced protonation of heme propionates in cytochrome c oxidase: Insights from surface enhanced resonance Raman spectroscopy and QM/MM calculations.

Understanding the coupling between heme reduction and proton translocation in cytochrome c oxidase (CcO) is still an open problem. The propionic acids of heme a3 have been proposed to act as a proton loading site (PLS) in the proton pumping pathway, yet this proposal could not be verified by experimental data so far. We have set up an experiment where the redox states of the two hemes in CcO can be controlled via external electrical potential. Surface enhanced resonance Raman (SERR) spectroscopy was applied to simultaneously monitor the redox state of the hemes and the protonation state of the heme propionates. Simulated spectra based on QM/MM calculations were used to assign the resonant enhanced CH2 twisting modes of the propionates to the protonation state of the individual heme a and heme a3 propionates respectively. The comparison between calculated and measured H2OD2O difference spectra allowed a sound band assignment. In the fully reduced enzyme at least three of the four heme propionates were found to be protonated whereas in the presence of a reduced heme a and an oxidized heme a3 only protonation of one heme a3 propionates was observed. Our data supports the postulated scenario where the heme a3 propionates are involved in the proton pathway.

[Microvascular obstruction due to thrombosis and fibrin deposition in myocardial infarction]. / Miyokart enfarktüsünde tromboz ve fibrin olusumu ile mikrovasküler tikanmanin gösterilmesi.

OBJECTIVE: It is widely known that myocardial damage is not immediately terminated after the elimination of epicardial occlusion in cases of myocardial infarction. In situ thrombosis during epicardial occlusion might contribute to poor myocardial perfusion after reperfusion of an occluded epicardial artery. In the current study, we sought to determine the effects of ischemia and reperfusion on microvascular thrombotic occlusion. METHODS: Thirty male Wistar rats were included in the study. After the rats had been anesthetized and thoracotomized, the left coronary artery was occluded for 30 minutes in the first group, and it was occluded for 30 minutes and reperfused for an additional 20 minutes in the second group. Ten rats were used as a sham-operated control group. After completion of the study protocol, excised heart preparations were analyzed by immunohistochemistry and electron microscopy. RESULTS: A significant difference was found between the infarction plus reperfusion group and the other 2 groups, with respect to microvascular fibrin and thrombocyte deposition in immunohistochemistry analysis. These results were confirmed by morphological examination with electron microscopy. CONCLUSION: In situ fibrin formation accompanies microvascular obstruction in acute myocardial infarction. Our results indicate that additional therapeutic approaches are needed in order to achieve better tissue perfusion in contemporary treatment of acute myocardial infarction after successful reopening of the infarct-related artery.

NirN protein from Pseudomonas aeruginosa is a novel electron-bifurcating dehydrogenase catalyzing the last step of heme d1 biosynthesis.

Heme d1 plays an important role in denitrification as the essential cofactor of the cytochrome cd1 nitrite reductase NirS. At present, the biosynthesis of heme d1 is only partially understood. The last step of heme d1 biosynthesis requires a so far unknown enzyme that catalyzes the introduction of a double bond into one of the propionate side chains of the tetrapyrrole yielding the corresponding acrylate side chain. In this study, we show that a Pseudomonas aeruginosa PAO1 strain lacking the NirN protein does not produce heme d1. Instead, the NirS purified from this strain contains the heme d1 precursor dihydro-heme d1 lacking the acrylic double bond, as indicated by UV-visible absorption spectroscopy and resonance Raman spectroscopy. Furthermore, the dihydro-heme d1 was extracted from purified NirS and characterized by UV-visible absorption spectroscopy and finally identified by high-resolution electrospray ionization mass spectrometry. Moreover, we show that purified NirN from P. aeruginosa binds the dihydro-heme d1 and catalyzes the introduction of the acrylic double bond in vitro. Strikingly, NirN uses an electron bifurcation mechanism for the two-electron oxidation reaction, during which one electron ends up on its heme c cofactor and the second electron reduces the substrate/product from the ferric to the ferrous state. On the basis of our results, we propose novel roles for the proteins NirN and NirF during the biosynthesis of heme d1.

Spectroscopic Observation of Calcium-Induced Reorientation of Cellobiose Dehydrogenase Immobilized on Electrodes and its Effect on Electrocatalytic Activity.

Cellobiose dehydrogenase catalyzes the oxidation of various carbohydrates and is considered as a possible anode catalyst in biofuel cells. It has been shown that the catalytic performance of this enzyme immobilized on electrodes can be increased by presence of calcium ions. To get insight into the Ca(2+) -induced changes in the immobilized enzyme we employ surface-enhanced vibrational (SERR and SEIRA) spectroscopy together with electrochemistry. Upon addition of Ca(2+) ions electrochemical measurements show a shift of the catalytic turnover signal to more negative potentials while SERR measurements reveal an offset between the potential of heme reduction and catalytic current. Comparing SERR and SEIRA data we propose that binding of Ca(2+) to the heme induces protein reorientation in a way that the electron transfer pathway of the catalytic FAD center to the electrode can bypass the heme cofactor, resulting in catalytic activity at more negative potentials.

Role of daytime polysomnography in the diagnosis of sleep apnea syndrome.

INTRODUCTION: Diagnosis of sleep apnea syndrome (SAS) depends on nocturnal polysomnography (nPSG), but waiting time for the test is long. Although, performing PSG in patients with excessive daytime sleepiness (EDS) at daytime (dPSG) was questioned, role and methods are not clear. The aim of the study was to assess the role of dPSG in the diagnosis of SAS, and the correlation between nPSG and dPSG. PATIENTS AND METHODS: Forty eight subjects, who were referred to our sleep laboratory with EDS were included to a cross-over study. Half of the patients underwent nPSG after dPSG, vice versa. Seven subjects excluded due to lack of participation. The rest (n= 41) had nPSG and dPSG. PSG recordings and analysis were performed according to AASM 2007 guideline. Results were analyzed for sleep efficiency, respiratory disturbance index (RDI), oxygen desaturation index (ODI), SAS severity and correlation between dPSG and nPSG. RESULTS: Total 41 subjects were analyzed. All patients had diagnosis of SAS. Sleep efficiency was higher at nPSG (86%), however also enough at dPSG (80%). Sleep stages of dPSG and nPSG were similar except stage 3 sleep, which was longer at nPSG. Undergoing dPSG or nPSG first did not correlate with sleep efficiency, respiratory disturbance (RDI) index, oxygen desaturation index (ODI) or severity of SAS. Despite BMI, neck circumference was closely related with RDI, ODI and severity. CONCLUSION: Daytime PSG, when performed appropriately, is an effective tool for diagnosing sleep disorders in patients with EDS. dPSG may decrease the amount of times that patients must wait to undergo PSG.

Distinct structural and redox properties of the heme active site in bacterial dye decolorizing peroxidase-type peroxidases from two subfamilies: resonance Raman and electrochemical study.

Spectroscopic data of dye decolorizing peroxidases (DyPs) from Bacillus subtilis (BsDyP), an A subfamily member, and Pseudomonas putida (PpDyP), a B subfamily enzyme, reveal distinct heme coordination patterns of the respective active sites. In solution, both enzymes show a heterogeneous spin population, with the six-coordinated low-spin state being the most populated in the former and the five-coordinated quantum mechanically mixed-spin state in the latter. We ascribe the poor catalytic activity of BsDyP to the presence of a catalytically incompetent six-coordinated low-spin population. The spin populations of the two DyPs are sensitively dependent on the pH, temperature, and physical, i.e., solution versus crystal versus immobilized, state of the enzymes. We observe a redox potential for the Fe(2+)/Fe(3+) couple in BsDyP (-40 mV) at pH 7.6 substantially more positive than those reported for the majority of other peroxidases, including PpDyP (-260 mV). Furthermore, we evaluate the potential of the studied enzymes for biotechnological applications on the basis of electrochemical and spectroelectrochemical data.

Anticoagulation with otamixaban and ischemic events in non-ST-segment elevation acute coronary syndromes: the TAO randomized clinical trial.

IMPORTANCE: The optimal anticoagulant for patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) managed with an invasive strategy remains controversial. OBJECTIVE: To compare the clinical efficacy and safety of otamixaban, a novel intravenous direct factor Xa inhibitor, with that of unfractionated heparin plus downstream eptifibatide in patients with NSTE-ACS undergoing a planned early invasive strategy. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, active-controlled superiority trial that enrolled 13,229 patients with NSTE-ACS and a planned early invasive strategy, at 568 active sites in 55 countries and conducted between April 2010 and February 2013. A planned interim analysis was conducted for otamixaban dose selection. INTERVENTIONS: Eligible participants were randomized to otamixaban (bolus and infusion, at 1 of 2 doses) or unfractionated heparin plus, at the time of percutaneous coronary intervention, eptifibatide. The otamixaban dose selected at interim analysis was an intravenous bolus of 0.080 mg/kg followed by an infusion of 0.140 mg/kg per hour. MAIN OUTCOMES AND MEASURES: The primary efficacy outcome was the composite of all-cause death or new myocardial infarction through day 7. RESULTS: Rates of the primary efficacy outcome were 5.5% (279 of 5105 patients) randomized to receive otamixaban and 5.7% (310 of 5466 patients) randomized to receive unfractionated heparin plus eptifibatide (adjusted relative risk, 0.99 [95% CI, 0.85-1.16]; P = .93). There were no differences for the secondary end points, including procedural thrombotic complications. The primary safety outcome of Thrombosis in Myocardial Infarction major or minor bleeding through day 7 was increased by otamixaban (3.1% vs 1.5%; relative risk, 2.13 [95% CI, 1.63-2.78]; P < .001). Results were consistent across prespecified subgroups. CONCLUSIONS AND RELEVANCE: Otamixaban did not reduce the rate of ischemic events relative to unfractionated heparin plus eptifibatide but did increase bleeding. These findings do not support the use of otamixaban for patients with NSTE-ACS undergoing planned early percutaneous coronary intervention. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01076764.

[The frequency and properties of REM related obstructive sleep apnea among the patients with mild related obstructive sleep apnea]. / Hafif obstrüktif uyku apneli hastalarda REM ile iliskili obstrüktif uyku apne sikligi ve özellikleri.

INTRODUCTION: The question if REM related obstructive sleep apnea (OSA) is a specific clinical entity or if it is an early sign of severe sleep disordered breathing as there is high occurrence of REM OSA in mild and moderate cases, recently have attracted the investigators. In this study, we aimed to see the frequency of REM related OSA among patients with mild OSA; and also to evaluate relation between apnea and daytime sleepiness among REM related OSA patients. MATERIALS AND METHODS: One hundred thirty four patients with mild OSA [Apnea hipopnea index (AHI)= 5-15] among 1267 patients with polysomnography examination at sleep laboratory of Bezmialem University Hospital between 1st August 2010 and 29th February 2012 were retrospectively evaluated. Patients having REM AHI/non-REM AHI ≥ 2 and non-REM AHI < 15 are considered as REM related OSA. RESULTS: Eighty (59%) of 134 patients with mild OSA were considered as REM related OSA. When REM related OSA and non REM OSA are compared for age, gender, daytime sleepiness, body mass index, neck surround and aditional diseases; mean age of REM related OSA group was found only significantly lower. Number of AHI in REM was over 15 at 87.3% of REM related OSA group and over 30 at 39.3% of them. There was no relation between REM AHI and daytime sleepiness symptom (p= 0.81). CONCLUSION: We may consider the result of lower mean age in REM related OSA group as a supporting result for early sign of severe sleep disordered breathing. We consider to follow up this group of patients to answer the question about subject.

[Relationship between symptoms of obstructive sleep apnea syndrome and traffic accidents in the city drivers]. / Sehir içi araç kullanan soförlerde obstrüktif uyku apne sendromu semptomlari ve trafik kazasi iliskisi.

INTRODUCTION: There is a high tendency for traffic accidents in patients with obstructive sleep apnea syndrome (OSAS). Thus it's recommended to investigate OSAS symptoms before certification of professional drivers. However, to what degree OSAS symptoms predict traffic accidents is not clear. We aimed to investigate the relationship between OSAS symptoms and traffic accidents. MATERIALS AND METHODS: Five hundred twenty bus drivers working at Istanbul Electricity, Tramway and Tunnel (IETT) general management were randomly selected. Berlin questionnaire was applied which included demographic data, accident ratios, total duration in profession, duration of working in a day and OSAS symptoms. Epworth sleepiness score (ESS) test was applied to assess day time slepiness. RESULTS: All drivers were male. Snoring were present in 324 (65.7%) of participants. Traffic accident history were present in 259 (49.7%) of drivers. Significant relationship was present between traffic accident and only daytime sleepiness among the OSAS symptoms. The mean of accident/year ratio of all participants were 0.092. Mean of ESS was 7.3 ± 3.2 for all participants. There is a positive correlation between ESS and accident/year ratio (r= 0.57, p= 0.012). CONCLUSION: Only daytime sleepiness among OSAS symptoms is related with traffic accident. The questioning of OSAS symptoms alone is inadequate to estimate traffic accident risk. Thus further consideration more than symptom questioning is needed at phase of authorization of professional drivers to detect OSAS.

Primary versus iatrogenic (post-PCI) coronary microvascular dysfunction: a wire-based multimodal comparison.

BACKGROUND: Although there are studies examining each one separately, there are no data in the literature comparing the magnitudes of the iatrogenic, percutaneous coronary intervention (PCI)-induced, microvascular dysfunction (Type-4 CMD) and coronary microvascular dysfunction (CMD) in the setting of ischaemia in non-obstructed coronary arteries (INOCA) (Type-1 CMD). OBJECTIVES: We aimed to compare the characteristics of Type-1 and Type-4 CMD subtypes using coronary haemodynamic (resistance and flow-related parameters), thermodynamic (wave energy-related parameters) and hyperemic ECG changes. METHODS: Coronary flow reserve (CFR) value of <2.5 was defined as CMD in both groups. Wire-based multimodal perfusion markers were comparatively analysed in 35 patients (21 INOCA/CMD and 14 CCS/PCI) enrolled in NCT05471739 study. RESULTS: Both groups had comparably blunted CFR values per definition (2.03±0.22 vs 2.11±0.37; p: 0.518) and similar hyperemic ST shift in intracoronary ECG (0.16±0.09 vs 0.18±0.07 mV; p: 0.537). While the Type-1 CMD was characterised with impaired hyperemic blood flow acceleration (46.52+12.83 vs 68.20+28.63 cm/s; p: 0.017) and attenuated diastolic microvascular decompression wave magnitudes (p=0.042) with higher hyperemic microvascular resistance (p<0.001), Type-4 CMD had blunted CFR mainly due to higher baseline flow velocity due to post-occlusive reactive hyperemia (33.6±13.7 vs 22.24±5.3 cm/s; p=0.003). CONCLUSIONS: The perturbations in the microvascular milieu seen in CMD in INOCA setting (Type-1 CMD) seem to be more prominent than that of seen following elective PCI (Type-4 CMD), although resulting reversible ischaemia is equally severe in the downstream myocardium.

Analyzing the catalytic processes of immobilized redox enzymes by vibrational spectroscopies.

Analyzing the structure and function of redox enzymes attached to electrodes is a central challenge in many fields of fundamental and applied life science. Electrochemical techniques such as cyclic voltammetry which are routinely used do not provide insight into the molecular structure and reaction mechanisms of the immobilized proteins. Surface-enhanced infrared absorption (SEIRA) and surface-enhanced resonance Raman (SERR) spectroscopy may fill this gap, if nanostructured Au or Ag are used as conductive support materials. In this account, we will first outline the principles of the methodology including a description of the most important strategies for biocompatible protein immobilization. Subsequently, we will critically review SERR and SEIRA spectroscopic approaches to characterize the protein and active site structure of the immobilized enzymes. Special emphasis is laid on the combination of surface-enhanced vibrational spectroscopies with electrochemical methods to analyze equilibria and dynamics of the interfacial redox processes. Finally, we will assess the potential of SERR and SEIRA spectroscopy for in situ investigations on the basis of the first promising studies on human sulfite oxidase and hydrogenases under turnover conditions.

Adsorption of sulfite oxidase on self-assembled monolayers from molecular dynamics simulations.

Sulfite oxidase (SO) is an enzyme catalyzing the terminal step of the metabolism of sulfur-containing amino acids that is essential for almost all living organisms. The catalytic activity of SO in vertebrates strongly depends on the efficiency of the intramolecular electron transfer (IET) between the catalytic Moco domain and the cytochrome b5 (cyt b5) domain. The IET process is assumed to be mediated by large domain motions of the cyt b5 domains within the enzyme. Thus, the interaction of SO with charged surfaces may affect the mobility of the cyt b5 domain required for IET and consequently hinder SO activation. In this study, we present a molecular dynamics approach to investigating the ionic strength dependence of the initial surface adsorption of SO in two different conformations-the crystallographic structure and the model structure for an activated SO-onto mixed amino- and hydroxyl-terminated SAMs. The results show for both conformations at low ionic strengths a strong adsorption of the cyt b5 units onto the SAM, which inhibits the domain motion event required for IET. Under higher ion concentrations, however, the interaction with the surface is weakened by the negatively charged ions acting as a buffer and competing in adsorption with the cathodic cyt b5 domains. This competition prevents the immobilization of the cytochrome b5 units onto the surface, allowing the intramolecular domain motions favoring IET. Our predictions support the interpretation of recent experimental spectroelectrochemical studies on SO.

Design of a peptidic turn with high affinity for Hg(II).

A four amino acid peptide containing the ß-turn template dPro-Pro in the middle and two cysteines (Cys) in the terminal positions (CdPPC) has been synthesized and its mercury(II) coordination properties studied using different spectroscopic methods. The UV-vis, CD, (199m)Hg PAC, and Raman spectroscopic studies indicate the binding of Hg(II) to the two Cys, forming the dithiolatemercury(II) complex Hg(CdPPC). Electrospray ionization mass spectrometry corroborates the 1:1 complex formation. A log K = 40.0 was determined for the formation constant of the Hg(CdPPC) complex using competition potentiometric studies. Replacement of the dPro-Pro motif by a Pro-Pro unit generated a peptide (CPPC) capable of forming a similar species [Hg(CPPC)] but showing a lower affinity for Hg(II) (at least 3-3.5 orders of magnitude lower). The introduction of the dPro-Pro motif is crucial to induce the folding of the CdPPC peptide into a ß-turn, preorganizing the two Cys for mercury(II) coordination. While the simple dPro-Pro unit mimics the overall preorganization achieved by the protein scaffold in metalloproteins containing the conserved metal ion chelation unit CXXC, the high thiophilicity of this metal stabilizes the final complex in a wide pH range (1.1-10). Using computational modeling, the structures of two conformers for Hg(CdPPC) have been optimized that differ mainly in the orientation of the plane containing S-Hg-S with respect to the anchoring C atoms.

Gradual Versus Abrupt Reperfusion During Primary Percutaneous Coronary Interventions in ST-Segment-Elevation Myocardial Infarction (GUARD).

Background Intramyocardial edema and hemorrhage are key pathological mechanisms in the development of reperfusion-related microvascular damage in ST-segment-elevation myocardial infarction. These processes may be facilitated by abrupt restoration of intracoronary pressure and flow triggered by primary percutaneous coronary intervention. We investigated whether pressure-controlled reperfusion via gradual reopening of the infarct-related artery may limit microvascular injury in patients undergoing primary percutaneous coronary intervention. Methods and Results A total of 83 patients with ST-segment-elevation myocardial infarction were assessed for eligibility and 53 who did not meet inclusion criteria were excluded. The remaining 30 patients with totally occluded infarct-related artery were randomized to the pressure-controlled reperfusion with delayed stenting (PCRDS) group (n=15) or standard primary percutaneous coronary intervention with immediate stenting (IS) group (n=15) (intention-to-treat population). Data from 5 patients in each arm were unsuitable to be included in the final analysis. Finally, 20 patients undergoing primary percutaneous coronary intervention who were randomly assigned to either IS (n=10) or PCRDS (n=10) were included. In the PCRDS arm, a 1.5-mm balloon was used to achieve initial reperfusion with thrombolysis in myocardial infarction grade 3 flow and, subsequently, to control distal intracoronary pressure over a 30-minute monitoring period (MP) until stenting was performed. In both study groups, continuous assessment of coronary hemodynamics with intracoronary pressure and Doppler flow velocity was performed, with a final measurement of zero flow pressure (primary end point of the study) at the end of a 60-minute MP. There were no complications associated with IS or PCRDS. PCRDS effectively led to lower distal intracoronary pressures than IS over 30 minutes after reperfusion (71.2±9.37 mm Hg versus 90.13±12.09 mm Hg, P=0.001). Significant differences were noted between study arms in the microcirculatory response over MP. Microvascular perfusion progressively deteriorated in the IS group and at the end of MP, and hyperemic microvascular resistance was significantly higher in the IS arm as compared with the PCDRS arm (2.83±0.56 mm Hg.s.cm-1 versus 1.83±0.53 mm Hg.s.cm-1, P=0.001). The primary end point (zero flow pressure) was significantly lower in the PCRDS group than in the IS group (41.46±17.85 mm Hg versus 76.87±21.34 mm Hg, P=0.001). In the whole study group (n=20), reperfusion pressures measured at predefined stages in the early reperfusion period showed robust associations with zero flow pressure values measured at the end of the 1-hour MP (immediately after reperfusion: r=0.782, P<0.001; at the 10th minute: r=0.796, P<0.001; and at the 20th minute: r=0.702, P=0.001) and peak creatine kinase MB level (immediately after reperfusion: r=0.653, P=0.002; at the 10th minute: r=0.597, P=0.007; and at the 20th minute: r=0.538, P=0.017). Enzymatic myocardial infarction size was lower in the PCRDS group than in the IS group with peak troponin T (5395±2991 ng/mL versus 8874±1927 ng/mL, P=0.006) and creatine kinase MB (163.6±93.4 IU/L versus 542.2±227.4 IU/L, P<0.001). Conclusions In patients with ST-segment-elevation myocardial infarction, pressure-controlled reperfusion of the culprit vessel by means of gradual reopening of the occluded infarct-related artery (PCRDS) led to better-preserved coronary microvascular integrity and smaller myocardial infarction size, without an increase in procedural complications, compared with IS. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02732080.