Detection of a Kinetically Competent Compound-I Intermediate in the Vancomycin Biosynthetic Enzyme OxyB.

Cytochrome P450 enzymes are abundantly encoded in microbial genomes. Their reactions have two general outcomes, one involving oxygen insertion via a canonical "oxygen rebound" mechanism and a second that diverts from this pathway and leads to a wide array of products, notably intramolecular oxidative cross-links. The antibiotic of-last-resort, vancomycin, contains three such cross-links, which are crucial for biological activity and are installed by the P450 enzymes OxyB, OxyA, and OxyC. The mechanisms of these enzymes have remained elusive in part because of the difficulty in spectroscopically capturing transient intermediates. Using stopped-flow UV/visible absorption and rapid freeze-quench electron paramagnetic resonance spectroscopies, we show that OxyB generates the highly reactive compound-I intermediate, which can react with a model vancomycin peptide substrate in a kinetically competent fashion to generate product. Our results have implications for the mechanism of OxyB and are in line with the notion that oxygen rebound and oxidative cross-links share early steps in their catalytic cycles.

Study of heart function in PRE-Eclampsia during and after PreGnancy (SHePREG): The pilot cohort.

BACKGROUND: Pre-eclampsia with severe features (severe PreE) is associated with heart dysfunction, yet the impact beyond pregnancy, including its association with cardiomyopathic genetic polymorphisms, remains poorly understood. OBJECTIVE: We aimed to characterize the temporal impact of severe PreE on heart function through the 4th trimester in women with and without deleterious cardiomyopathic genetic variants. METHODS: Pregnant women were enrolled to undergo transthoracic echocardiography (TTE) in late pregnancy and 3 months postpartum. In women with severe PreE a targeted approach to identify pathogenic cardiomyopathic genetic polymorphisms was undertaken, and heart function was compared in carriers and noncarriers. RESULTS: Pregnant women (32 ± 4 years old, severe PreE = 14, control = 8) were enrolled between 2019 - 2021. Women with severe PreE displayed attenuated myocardial relaxation (mitral e' = 11.0 ± 2.2 vs 13.2 ± 2.3 cm/sec, P < .05) in late pregnancy, and on in-silico analysis, deleterious cardiomyopathic variants were found in 58%. At 103 ± 33 days postpartum, control women showed stability in myocardial relaxation (Mitral e' Entry: 13.2 ± 2.3 vs Postpartum: 13.9 ± 1.7cm/sec, P = .464), and genetic negative severe PreE women (G-) demonstrated recovery of diastolic function to control level (Mitral e' Entry: 11.0 ± 3.0 vs Postpartum 13.7 ± 2.8cm/sec, P < .001), unlike their genetic positive (G+) counterparts (Mitral e' Entry: 10.5 ± 1.7 vs Postpartum 10.8 ± 2.4cm/sec, P = .853). CONCLUSIONS: Postpartum recovery of heart function after severe PreE is attenuated in women with deleterious cardiomyopathic genetic polymorphisms.

Catheter ablation of atrial fibrillation in patients with cor triatriatum sinister; case series and review of literature.

INTRODUCTION: Cor triatriatum sinister (CTS) is a rare congenital heart defect characterized by fibromuscular septation of the left atrium associated with atrial fibrillation (AF). The incidence of hemodynamically insignificant CTS in the AF ablation population and effect on ablation success are not known. Furthermore, little is known about the potential effect of CTS on arrhythmogenic substrate. OBJECTIVE: We define the incidence of hemodynamically insignificant CTS in patients undergoing AF ablation with RF and cryoballoon ablation, the technical challenges created by the left atrial partitioning, and the potentially arrhythmogenic effects of the membrane. We also review the literature of CA in patients with CTS. METHODS: First-time AF ablation cases at our institution over a 10-year period were screened to identify patients with CTS. Retrospective review was performed to obtain clinical characteristics and ablation data. RESULTS: Of the 3953 consecutive patients undergoing initial AF ablation during the study period, four patients (0.10%) had CTS. Ablation was successful acutely in all patients. One patient had recurrent AF and required repeat ablation for a single procedure success rate of 75% and multi-procedure success rate of 100%. The CTS membrane was associated with low voltage zones in the two patients in whom it was measured and with substrate for macro-reentrant atrial tachycardia in one of these patients. CONCLUSION: The incidence of hemodynamically insignificant CTS in patients undergoing CA for AF is very low, but does not serve as a significant barrier to successful ablation as long as directed access to the superoposterior chamber is obtained.

Effect of redox-responsive DTSSP crosslinking on poly(l-lysine)-grafted-poly(ethylene glycol) nanoparticles for delivery of proteins.

Therapeutic proteins are utilized in a variety of clinical applications, but side effects and rapid in vivo clearance still present hurdles. An approach that addresses both drawbacks is protein encapsulation within in a polymeric nanoparticle, which is effective but introduces the additional challenge of destabilizing the nanoparticle shell in clinically relevant locations. This study examined the effects of crosslinking self-assembled poly(l-lysine)-grafted-poly(ethylene glycol) nanoparticles with redox-responsive 3,3'-dithiobis(sulfosuccinimidyl propionate) (DTSSP) to achieve nanoparticle destabilization in a reductive environment. The polymer-protein nanoparticles (DTSSP NPs) were formed through electrostatic self-assembly and crosslinked with DTSSP, which contains a glutathione-reducible disulfide. As glutathione is upregulated in various cancers, DTSSP NPs could display destabilization within cancer cells. A library of DTSSP NPs was formed with varying copolymer to protein (C:P) and crosslinker to protein (X:P) mass ratios and characterized by size and encapsulation efficiency. DTSSP NPs with a 7:1 C:P ratio and 2:1 X:P ratio were further characterized by stability in the presence proteases and reducing agents. DTSSP NPs fully encapsulated the model protein and displayed 81% protein release when incubated with 5 mM dithiothreitol for 12 hr. This study contributes to understanding stimulus-responsive crosslinking of polymeric nanoparticles and could be foundational to clinical administration of therapeutic proteins.

Treatment of chemotherapy-associated cardiomyopathy.

PURPOSE OF REVIEW: The number of cancer survivors is increasing, and cardiovascular events are a significant cause of morbidity and mortality in these patients. Preexisting cardiovascular conditions as well as the development of cancer therapeutics-related cardiac dysfunction (CTRCD), in particular left ventricular dysfunction and heart failure, limit the options for cancer therapies for these patients and contribute to reduced cancer survival. RECENT FINDINGS: Recent guidelines and position statements from various cardiology and oncology societies provide an outline for the practicing physician for the management of CTRCD. However, this is largely based on data extrapolated from the general heart failure population (including patients without cancers) and is not based on strong evidence. There is now emerging evidence for the prevention and treatment of heart failure related to certain established chemotherapeutic drugs, whereas there is lack of trials for specific cardioprotective strategies to reduce cardiotoxicity of newer targeted cancer therapies. SUMMARY: In this article, we discuss the most recent literature for the management of asymptomatic left ventricular dysfunction and heart failure related to chemotherapy, from prevention to the use of goal-directed medical therapies as well as discuss the role for advanced heart failure treatment in this population.

Ethical Considerations in the Long-Term Ventricular Assist Device Patient.

PURPOSE OF REVIEW: As the heart failure population continues to age, the need for definitive therapies such as ventricular assist devices (VADs) to extend life and alleviate suffering from end-stage disease directly increases. The goal of this article is to examine the ethical principles of autonomy, beneficence, non-maleficence, and justice within the context of long-term VAD patients. RECENT FINDINGS: Survival rates in VAD-implanted patients have improved in parallel with modernization of device design and surgical technique, reaching that of cardiac transplantation at 1 year post-procedure. Even the sickest patients, those once deemed transplant-ineligible, have been proven to benefit from device implantation and in some cases to a point of becoming eligible for cardiac transplantation. Nevertheless, VAD implantation remains a high-risk procedure with in-hospital mortality rates reaching up to 27% post-procedure and requires intensive upkeep even after successful implantation. Furthermore, end-of-life decisions are complicated by consideration of device deactivation in patients who may not die immediately from an otherwise lethal pathophysiology. Ethical considerations in selection of patients, goals of implantation, and length of therapy become important to preserve the efficacy of treatment and maximize resource utilization. Advanced directives, shared decision-making, and multi-disciplinary approach to treatment have been shown to improve outcomes with respect to both survival and quality of life.

Mustard baffle obstruction and leak - How successful are percutaneous interventions in adults?

Atrial switch operations for D-Transposition of the great arteries (D-TGA) were performed until the late 20th century. These patients have substantial rates of re-operation, particularly for baffle related complications. This study sought to analyze the efficacy of percutaneous transcatheter intervention (PTI) for baffle leak and/or stenosis in adult atrial switch patients. Adult patients with a prior atrial switch operation who underwent heart catheterization (2002-2014) at a tertiary adult congenital heart disease referral center were retrospectively analyzed. In 58 adults (30 ± 8 years, 75% men, 14% New York Heart Association (NYHA) functional class ≥2) who underwent 79 catheterizations, PTI was attempted in 50 (baffle leak (n = 10, 20%), stenosis (n = 27, 54%), or both (n = 13, 26%)). PTI was successful in 45 and 5 were referred for surgery due to complex anatomy. A total of 40 bare metal stents, 18 covered stents, 16 occlusion devices, 2 angioplasties, and 1 endovascular graft were deployed. In isolated stenosis, there was improvement in NYHA functional class after PTI (8 vs. 0 patients were NYHA FC > 2, p = 0.004), which was matched by improvement in maximal oxygen consumption on exercise testing (VO2) (25.1 ± 5.4 mL/kg/min vs. 27.9 ± 9 mL/kg/min, p = 0.03). There were no procedure-related deaths or emergent surgeries in this cohort. This single-center cohort is the largest reported series of adult atrial switch operation patients who have undergone PTI for baffle stenosis and/or leak. We demonstrate that PTI with an expert multi-disciplinary team is a safe and effective alternative to surgery in adult patients with an atrial switch operation.

Exercise is associated with better erectile function in men under 40 as evaluated by the International Index of Erectile Function.

INTRODUCTION: Studies have shown an association between erectile dysfunction and sedentary lifestyle in middle-aged men, with a direct correlation between increased physical activity and improved erectile function. Whether or not this relationship is present in young, healthy men has yet to be demonstrated. AIM: The aim of this study was to assess the association between physical activity and erectile function in young, healthy men. MAIN OUTCOME MEASURES: The primary end points for our study were: (i) differences in baseline scores of greater than one point per question for the International Index of Erectile Function (IIEF); (ii) differences in baseline scores of greater than one point per question for each domain of the IIEF; (iii) exercise energy expenditure; and (iv) predictors of dysfunction as seen on the IIEF. METHODS: The participants were men between the ages of 18 and 40 years old at an academic urology practice. Patients self-administered the Paffenbarger Physical Activity Questionnaire and the IIEF. Patients were stratified by physical activity into two groups: a sedentary group (≤1,400 calories/week) and an active group (>1,400 calories/week). Men presenting for the primary reason of erectile dysfunction or Peyronie's disease were excluded. RESULTS: Seventy-eight patients had complete information in this study: 27 patients (34.6%) in the sedentary group (≤1,400 kcal/week) and 51 patients (65.4%) in the active group (>1,400 kcal/week). Sedentary lifestyle was associated with increased dysfunction in the following domains of the IIEF: erectile function (44.4% vs. 21.6%, P = 0.04), orgasm function (44.4% vs. 17.7%, P = 0.01), intercourse satisfaction (59.3% vs. 35.3%, P = 0.04), and overall satisfaction (63.0% vs. 35.3%, P = 0.02). There was a trend toward more dysfunction in the sedentary group for total score on the IIEF (44.4% vs. 23.5%, P = 0.057), while sexual desire domain scores were similar in both groups (51.9% vs. 41.2%, P = 0.37). CONCLUSIONS: We have demonstrated that increased physical activity is associated with better sexual function measured by a validated questionnaire in a young, healthy population. Further studies are needed on the long-term effects of exercise, or lack thereof, on erectile function as these men age.

Novel Technique of Surgical Management of Scimitar Syndrome.

Scimitar syndrome is a rare congenital abnormality resulting from right-sided pulmonary venous return to the inferior vena cava rather than to the left atrium. It is usually detected in early childhood with symptoms of recurrent chest infection and finding of pulmonary hypertension due to left to right shunt. We report a case of a 40-year-old woman with scimitar syndrome discovered on chest X-ray during evaluation of recurrent pneumonia. Surgical correction was achieved with a novel technique of using a synthetic graft connecting the scimitar vein across the right atrium to the left atrium along with ligation of the scimitar vein connection to the inferior vena cava. The patient continues to do well 10 years after surgery, and the shunt graft shows good flow on echocardiogram. We present her clinical and imaging data and details of the surgical technique along with a brief review of surgical literature.

Percutaneous Coronary Intervention in an 8-Month-Old Infant for Ostial Stenosis of a Reimplanted Left Main Coronary Artery.

Percutaneous coronary intervention (PCI) is a routine procedure undertaken in adult patients. In children, the procedure remains rare and challenging due to a multitude of factors including but not limited to complex congenital heart disease anatomy, catheter and stent to patient size mismatch, and lack of data for post-PCI antiplatelet therapy. We present a case of PCI in an 8-month-old infant with anomalous left coronary artery from pulmonary artery (ALCAPA) who developed severe ostial kinking of the left main coronary artery (LMCA) after surgical reimplantation of the anomalous coronary. A 3.5 × 8 mm Vision bare metal stent was successfully placed into the LMCA and postdilated with excellent results. Follow-up echocardiography at 6 months post-PCI demonstrated a patent stent with normal Doppler flow signals. Despite initial success, the infant developed severe heart failure and was listed for orthotopic heart transplantation at age 20 months, one year after PCI. Given the paucity of published data regarding PCI and outcomes in infants with ALCAPA after surgical reimplantation, we describe our case and present a review of the available literature.

Management of recurrent urethral strictures after hypospadias repair: is there a role for repeat dilation or endoscopic incision?

OBJECTIVE: Urethral strictures are among the most common complications after hypospadias repair. We report our 10-year experience with endoscopic incision or dilation of urethral strictures after hypospadias repair, to determine the best management technique. METHODS: All cases of urethral strictures after hypospadias repair treated with direct vision internal urethrotomy (DVIU), dilation or urethroplasty at our institution from 1997 to 2007 were included. Records were reviewed and clinical parameters analyzed. Data were statistically analyzed to identify risk factors for stricture recurrence after initial or subsequent treatment(s). RESULTS: Of 2273 patients, 73 were treated for a postoperative urethral stricture and 15 others were referred for stricture treatment. Of these 88 patients, 39 were treated with initial dilation or DVIU and 49 underwent urethroplasty or reoperative hypospadias repair. Fifteen (38%) of the patients treated with initial DVIU or dilation showed no recurrence. Of the patients that did have a recurrence, a repeat DVIU or dilation had a success rate of 17% with no difference in success between these two groups. Choice of therapy between repeat dilation/DVIU and urethroplasty at the second procedure showed a statistically significant higher success rate in the urethroplasty group (67% vs 17%, P=0.03). CONCLUSION: Although numbers are small, our data suggest that if there is recurrent stricture after initial DVIU/dilation then a formal urethroplasty has a significantly higher success rate than repeat DVIU/dilation.