Contribution of calcium ligands in substrate binding and product release in the Acetovibrio thermocellus glycoside hydrolase family 9 cellulase CelR.

Enzymatic deconstruction of lignocellulosic biomass is crucial to establishment of the renewable biofuel and bioproduct economy. Better understanding of these enzymes, including their catalytic and binding domains, and other features offer potential avenues for improvement. Glycoside hydrolase family 9 (GH9) enzymes are attractive targets because they have members that exhibit exo- and endo-cellulolytic activity, processivity of reaction, and thermostability. This study examines a GH9 from Acetovibrio thermocellus ATCC 27405, AtCelR containing a catalytic domain and a carbohydrate binding module (CBM3c). Crystal structures of the enzyme without substrate, bound to cellohexaose (substrate) or cellobiose (product), show the positioning of ligands to calcium and adjacent residues in the catalytic domain that may contribute to substrate binding and facilitate product release. We also investigated the properties of the enzyme engineered to contain an additional carbohydrate binding module (CBM3a). Relative to the catalytic domain alone, CBM3a gave improved binding for Avicel (a crystalline form of cellulose), and catalytic efficiency (kcat/KM) was improved 40× with both CBM3c and CBM3a present. However, because of the molecular weight added by CBM3a, the specific activity of the engineered enzyme was not increased relative to the native construct consisting of only the catalytic and CBM3c domains. This work provides new insight into a potential role of the conserved calcium in the catalytic domain and identifies contributions and limitations of domain engineering for AtCelR and perhaps other GH9 enzymes.

Temporary mechanical support in the peripartum patient as a bridge to postpartum recovery: A report of three cases.

Cardiogenic shock (CS) is a severe complication of peripartum cardiomyopathy (PPCM). Patients with deteriorating CS often require temporary mechanical circulatory support. In PPCM, this can be used as a bridge to postpartum recovery or bridge to decision. The outcomes are unclear, especially if prolonged utilization is required. We present a case series of three patients with PPCM in deteriorating CS who were successfully supported with a ventricular assist device or veno-arterial extracorporeal membrane oxygenation as a bridge to postpartum recovery.

Exploratory structural equation modeling: a streamlined step by step approach using the R Project software.

Confirmatory Factor Analysis (CFA) has been a popular yet limited approach to assessing latent factor structures. Despite items rarely loading exclusively on one latent factor in multifactorial scales, CFA assumes all indicators/items should load uniquely on their allocated latent dimensions. To address this weakness, Exploratory Structural Equation Modeling (ESEM) combines exploratory factor analyses (EFA) and CFA procedures, allowing cross-loadings to occur when assessing hypothesized models. Although such advantages have enhanced ESEM popularity, its adoption is often limited by software rigidity and complex coding difficulties. To address these obstacles, the current tutorial presents a streamlined, step-by-step approach using the open-source software R while providing both R and Mplus ESEM syntax. The tutorial demonstrates the sequence of the ESEM stages by examining the frequently debated Strengths and Difficulties Questionnaire (SDQ) factor structure, using openly accessible data from the Longitudinal Study of Australian Children (LSAC). As ESEM may allow a better understanding of the complex associations in multidimensional scales, this tutorial may optimize the epidemiological and clinical assessment of common yet multifaceted psychiatric presentations.

Impact of Laparoscopic Sleeve Gastrectomy on Cardiovascular Pharmacotherapy in Left Ventricular Assist Device Patients.

ABSTRACT: Left ventricular assist device (LVAD) implantation is increasingly utilized in patients with advanced heart failure and morbid obesity. Laparoscopic sleeve gastrectomy (LSG) can facilitate weight loss in this population and can ultimately change the pharmacokinetics of heart failure therapeutics. In this study, we aimed to explore the changes in cardiovascular pharmacotherapy post LSG intervention. We conducted a retrospective observational cohort study of morbidly obese LVAD patients between 2013 and 2019 at the University of Florida with available pharmacotherapeutic data at 1 and 6 months. Thirteen post-LSG patients and 13 control subjects were included in the final analysis. In the post-LSG group, the mean body mass index decreased significantly (44 ± 5 vs. 34 ± 4.9, P < 0.001), and 7 patients were successfully bridged to cardiac transplantation. Only 3 patients required adjustment of their LVAD speed. Mean return to flow decreased by 8 mm Hg, despite a 45% reduction in the mean number of vasodilators per patient (1.2 vs. 0.7, P = 0.03). Mean weekly warfarin dose decreased by 35% after 6 months (32.9 ± 20.9 vs. 50.7 ± 26.6, P = 0.01). The use of diuretics, vasodilators, and beta-blockers was significantly reduced by 50%, 45%, and 35%, respectively. None of these changes were observed in the control group at 6-month follow-up post LVAD. In this single-center experience, weight loss post LSG is associated with decreased vasodilator, diuretic, and anticoagulant medication requirements in LVAD patients.

Triple therapy temporary mechanical circulatory support as a bridge to triple-organ transplantation.

Temporary mechanical circulatory support (MCS) systems are indicated to stabilize hemodynamically decompensating patients in cardiogenic shock refractory to medical management. These devices are currently used as short-term hemodynamic support to facilitate organ recovery or bridge to definitive therapy with durable MCS or heart transplantation. We present the sequential use of intra-aortic balloon pump, Impella 5.5®, and venoarterial extracorporeal membrane oxygenation as a bridge to heart-liver-kidney transplantation. The patient was supported for 78 days on Impella 5.5 and 95 days total temporary MCS. He had an uncomplicated postoperative course after triple-organ transplantation and was stable with no signs of rejection at 1-, 3-, 6-, and 12-month follow-up.

Hemodynamic effects of ivabradine use in combination with intravenous inotropic therapy in advanced heart failure.

Intravenous inotropic therapy can be used in patients with advanced heart failure, as palliative therapy or as a bridge to cardiac transplantation or mechanical circulatory support, as well as in cardiogenic shock. Their use is limited to increasing cardiac output in low cardiac output states and reducing ventricular filling pressures to alleviate patient symptoms and improve functional class. Many advanced heart failure patients have sinus tachycardia as a compensatory mechanism to maintain cardiac output. However, excessive sinus tachycardia caused by intravenous inotropes can increase myocardial oxygen consumption, decrease coronary perfusion, and at extreme heart rates decrease ventricular filling and stroke volume. The limited available hemodynamic studies support the hypothesis that adding ivabradine, a rate control agent without negative inotropic effect, may blunt inotrope-induced tachycardia and its associated deleterious effects, while optimizing cardiac output by increasing stroke volume. This review analyzes the intriguing pathophysiology of combined intravenous inotropes and ivabradine to optimize the hemodynamic profile of patients in advanced heart failure. Graphical abstract Illustration of the beneficial and deleterious hemodynamic effects of intravenous inotropes in advanced heart failure, and the positive effects of adding ivabradine.

A mini-thoracotomy approach for walking veno-arterial extracorporeal membranous oxygenation.

Fulminant myocarditis is a rapidly progressive myocardial inflammation that commonly requires advanced circulatory support therapies. We report our management of a 36-year-old gentleman with fulminant myocarditis who we managed with extracorporeal membranous oxygenation (ECMO) and subsequently durable bi-ventricular assist devices as a bridge to heart transplantation. The patient was admitted after a 1-week history of malaise with severe lethargy, jugular venous distension to greater than 10 cm, and troponin elevation to greater than 27 K. He was taken immediately for a heart catheterization which showed no obstructive coronary disease, and hemodynamics consistent with bi-ventricular failure. We proceeded with ECMO for hemodynamic support, utilizing a mini-thoracotomy for cannulation. A Protek Duo Rapid Deployment (LivaNova) was inserted via a modified Seldinger technique through the left ventricular apex, terminating in the ascending aorta. Percutaneous right IJ bicaval via a y-ed Avalon Elite (Getinge) was employed for venous drainage. This case highlights an alternate strategy for central walking veno-arterial ECMO in a patient presenting with fulminant myocarditis with a platform that minimizes upper/lower extremity over/under perfusion complications, while providing sternal sparring antegrade arterial flow with simultaneous ventricular unloading/venting.

Pulmonary Artery Proportional Pulse Pressure (PAPP) Index Identifies Patients With Improved Survival From the CardioMEMS Implantable Pulmonary Artery Pressure Monitor.

BACKGROUND: Pulmonary artery proportional pulse pressure (PAPP) was recently shown to have prognostic value in heart failure (HF) with reduced ejection fraction (HFrEF) and pulmonary hypertension. We tested the hypothesis that PAPP would be predictive of adverse outcomes in patients with implantable pulmonary artery pressure monitor (CardioMEMS™ HF System, St. Jude Medical [now Abbott], Atlanta, GA, USA). METHODS: Survival analysis with Cox proportional hazards regression was used to evaluate all-cause deaths and HF hospitalisation (HFH) in CHAMPION trial1 patients who received treatment with the CardioMEMS device based on the PAPP. RESULTS: Among 550 randomised patients, 274 had PAPP ≤ the median value of 0.583 while 276 had PAPP>0.583. Patients with PAPP≤0.583 (versus PAPP>0.583) had an increased risk of HFH (HR 1.40, 95% CI 1.16-1.68, p=0.0004) and experienced a significant 46% reduction in annualised risk of death with CardioMEMS treatment (HR 0.54, 95% CI 0.31-0.92) during 2-3 years of follow-up. This survival benefit was attributable to the treatment benefit in patients with HFrEF and PAPP≤0.583 (HR 0.50, 95% CI 0.28-0.90, p<0.05). Patients with PAPP>0.583 or HF with preserved EF (HFpEF) had no significant survival benefit with treatment (p>0.05). CONCLUSION: Lower PAPP in HFrEF patients with CardioMEMS constitutes a higher mortality risk status. More studies are needed to understand clinical applications of PAPP in implantable pulmonary artery pressure monitors.

Leadless pacemaker use in a patient with a durable left ventricular assist device.

There is limited known safety and efficacy of leadless pacemaker device use in patients with durable left ventricular assist devices (LVADs). We present a case of a pacemaker-dependent LVAD patient with infection of permanent transvenous pacemaker who underwent successful implantation of Micra transcatheter pacing system (Medtronic).

Utilizing the index for mortality prediction after cardiac transplantation risk score to predict hospital resource consumption.

OBJECTIVE: The index for mortality prediction after cardiac transplantation (IMPACT) risk score incorporates 12 preoperative recipient-specific variables, and has been validated as an accurate predictor of short- and long-term mortality after orthotopic heart transplantation (OHTx). We believe it can also be used to predict hospital costs, and we hypothesize that higher preoperative IMPACT risk scores are associated with increased hospital resource consumption. METHODS: All OHTx patients ≥18 years of age at our institution were reviewed from 1 January 2000 to 31 December 2014. Total index hospitalization costs post-transplant were extracted and presented in 2014 consumer price index inflation-adjusted US dollars. Patients were stratified into quartiles (Q) according to IMPACT risk scores. Logarithmic transformation normalized cost data, and linear regression assessed for correlation. A comparison of cost between Q of IMPACT risk score was performed using rank-sum and Kruskal-Wallis tests. Survival was estimated using the Kaplan-Meier method. RESULTS: Three hundred fifty-six (n = 356) OHTx were performed during the study period. The median IMPACT score for the cohort was five (interquartile range [IQR] 3-6). Eight (2.2%) patients died within 30-days and 1-year Kaplan-Meier survival was 88.3%. The median length of stay (LOS) was 16 (IQR 14-24) days. The median hospital cost for index admission was $222 200 (IQR:$169 200-$313 700). Median LOS was longer in Q4 vs Q1 (18 days vs 15 days, P = .01) and index hospital costs in Q4 were significantly higher compared to Q1 patients ($280 400 vs $205 000, P < .01). There was a significant positive correlation between IMPACT risk score and cost (regression coefficient .04, P < .01). CONCLUSION: This is the first study in adult cardiac transplantation to identify a positive correlation between hospital cost and recipient risk using the IMPACT risk score. Cost and resource consumption for the index admission after OHTx were significantly higher in the highest IMPACT risk Q compared with patients in the lowest Q.

Early versus standard renal replacement therapy after left ventricular assist device implantation.

OBJECTIVES: Renal function may improve after left ventricular assist device (LVAD) implant, however, some patients develop postoperative acute kidney injury (AKI). Randomized trials showed benefit for early renal replacement therapy (RRT) in critically ill patients with AKI, but this practice has not been studied in LVAD patients. METHODS: We performed a single-center, retrospective cohort study of all adults (>18 years) who underwent LVAD placement from 1/2010 to 12/2018. We collected preoperative, hemodynamic, echocardiographic, intraoperative, and postoperative data. AKI was defined according to Kidney Disease: Improving Global Outcomes definition. Early (E) RRT was considered treatment at AKI stage II or below. Standard (S) RRT was considered treatment at AKI stage III. Outcomes and Kaplan-Meier analysis were compared between groups. RESULTS: A total of 184 patients were included (mean age 56.10 years, 81% males, 30.4% African-American race). A total of 71 (38.6%) developed AKI and 17 (9.24%) needed RRT (11 E vs 6 S). A total of 11 remained hemodialysis-dependent at discharge (5 [45.5%] in E vs 6 [100%] in S, P = .043). There was a trend toward shorter intensive care unit stay and ventilation time in E group, and overall hospital stay was significantly less in the E group (48.18 ± 25.95 vs 94.00 ± 53.07 days, P = .028). Thirty-day mortality was similar between groups (E 18% vs S 16%, P = .9), but there was a trend toward improved overall survival in the E group. CONCLUSION: This is the first study to examine early initiation of RRT after LVAD implant. Early RRT was associated with shorter hospital stay, lower need for permanent RRT, and a trend toward improved survival. This practice may provide significant cost savings and should be examined further.

Increased Pulmonary-Systemic Pulse Pressure Ratio Is Associated With Increased Mortality in Group 1 Pulmonary Hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is characterised by remodelling of the pulmonary vasculature leading to right ventricular (RV) failure. The failing RV, through interventricular uncoupling, deleteriously impacts the left ventricle and overall cardiac efficiency. We hypothesised that the ratio of the pulmonary artery pulse pressure to the systemic pulse pressure ("pulmonary-systemic pulse pressure ratio", or PS-PPR) would be associated with mortality in PAH. METHODS: We conducted a retrospective analysis of 262 patients in the National Institute of Health Primary Pulmonary Hypertension Registry (NIH-PPH). We evaluated the association between the PS-PPR and mortality after adjustment for the Pulmonary Hypertension Connection (PHC) risk equation. RESULTS: Among 262 patients (mean age 37.5±15.8years, 62.2% female), median PS-PPR was 1.04 (IQR 0.79-1.30). In the Cox proportional hazards regression model, each one unit increase in the PS-PPR was associated with more than a two-fold increase in mortality during follow-up (HR 2.06, 95% CI 1.40-3.02, p=0.0002), and this association of PS-PPR with mortality remained significant in the multivariable Cox model adjusted for the PHC risk equation, mean pulmonary artery pressure, and body mass index (BMI) (adjusted HR 1.81, 95% CI 1.13-2.88, p=0.01). Furthermore, PS-PPR in the upper quartile (>1.30) versus quartiles 1-3 was associated with a 68% increase in mortality after adjustment for these same covariates (adjusted HR 1.68, 95% CI 1.13-2.50, p=0.01). CONCLUSIONS: Pulmonary-systemic pulse pressure ratio, a marker of biventricular efficiency, is associated with survival in PAH even after adjustment for the PHC risk equation. Further studies are needed on the wider applications of PS-PPR in PAH patients.

AMPK activation protects from neuronal dysfunction and vulnerability across nematode, cellular and mouse models of Huntington's disease.

The adenosine monophosphate activated kinase protein (AMPK) is an evolutionary-conserved protein important for cell survival and organismal longevity through the modulation of energy homeostasis. Several studies suggested that AMPK activation may improve energy metabolism and protein clearance in the brains of patients with vascular injury or neurodegenerative disease. However, in Huntington's disease (HD), AMPK may be activated in the striatum of HD mice at a late, post-symptomatic phase of the disease, and high-dose regiments of the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide may worsen neuropathological and behavioural phenotypes. Here, we revisited the role of AMPK in HD using models that recapitulate the early features of the disease, including Caenorhabditis elegans neuron dysfunction before cell death and mouse striatal cell vulnerability. Genetic and pharmacological manipulation of aak-2/AMPKα shows that AMPK activation protects C. elegans neurons from the dysfunction induced by human exon-1 huntingtin (Htt) expression, in a daf-16/forkhead box O-dependent manner. Similarly, AMPK activation using genetic manipulation and low-dose metformin treatment protects mouse striatal cells expressing full-length mutant Htt (mHtt), counteracting their vulnerability to stress, with reduction of soluble mHtt levels by metformin and compensation of cytotoxicity by AMPKα1. Furthermore, AMPK protection is active in the mouse brain as delivery of gain-of-function AMPK-γ1 to mouse striata slows down the neurodegenerative effects of mHtt. Collectively, these data highlight the importance of considering the dynamic of HD for assessing the therapeutic potential of stress-response targets in the disease. We postulate that AMPK activation is a compensatory response and valid approach for protecting dysfunctional and vulnerable neurons in HD.

Validation of clinical prognostic scores for patients treated with curative-intent for recurrent colorectal liver metastases.

BACKGROUND: Scoring systems were developed to stratify patients with colorectal liver metastases considered for liver resection into different risk groups. Such scores have never been evaluated in recurrent liver metastases. The aim of this study was to evaluate whether these scores are applicable to patients with recurrent colorectal liver metastases and treated with curative intent. METHODS: We retrospectively analyzed data from 375 consecutive patients who underwent liver surgery for colorectal liver metastases between June 2010 and August 2015. Seventy-three patients developed liver-limited recurrence treated with curative intent. The predictive value of 6 scores (Fong, Sofocleous, Nagashima, Nordlinger, Konopke, and the Basingstoke index) was assessed in this set of patients. RESULTS: Median follow-up was 36.2 months. Overall survival and progression-free survival were 33.6 and 5.6 months, respectively. When scores were applied for OS, none showed a significant stratification between patients, although Nagashima's score showed a significant difference in overall survival between patients from the low-risk group and those from the intermediate- and high-risk groups (40.8 vs 30.5 months, P = 0.039). For PFS, only Fong's score showed a statistically significant stratification (6.6 vs 4.7 months, P = 0.027). CONCLUSION: Scoring systems are of limited-value in stratifying patients operated on for recurrent colorectal liver metastases.

Genetic variants in novel pathways influence blood pressure and cardiovascular disease risk.

Blood pressure is a heritable trait influenced by several biological pathways and responsive to environmental stimuli. Over one billion people worldwide have hypertension (≥140 mm Hg systolic blood pressure or ≥90 mm Hg diastolic blood pressure). Even small increments in blood pressure are associated with an increased risk of cardiovascular events. This genome-wide association study of systolic and diastolic blood pressure, which used a multi-stage design in 200,000 individuals of European descent, identified sixteen novel loci: six of these loci contain genes previously known or suspected to regulate blood pressure (GUCY1A3-GUCY1B3, NPR3-C5orf23, ADM, FURIN-FES, GOSR2, GNAS-EDN3); the other ten provide new clues to blood pressure physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke and coronary artery disease, but not kidney disease or kidney function. We also observed associations with blood pressure in East Asian, South Asian and African ancestry individuals. Our findings provide new insights into the genetics and biology of blood pressure, and suggest potential novel therapeutic pathways for cardiovascular disease prevention.

Development of suicide postvention guidelines for secondary schools: a Delphi study.

BACKGROUND: Suicide of school-aged adolescents is a significant problem, with serious implications for students and staff alike. To date, there is a lack of evidence regarding the most effective way for a secondary school to respond to the suicide of a student, termed postvention [(Crisis 33:208-214, 2012), (Crisis 34:164-182, 2013)]. The aim of this study was to employ the expert consensus (Delphi) methodology to the development of a set of guidelines, to assist English-speaking secondary schools to develop a plan to respond to a student suicide, or to respond to a suicide in the absence of a predetermined plan. METHODS: The Delphi methodology was employed, which involved a two-stage process. Firstly, medical and research databases, existing postvention guidelines developed for schools, and lay literature were searched in order to identify potential actions that school staff could carry out following the suicide of a student. Based on this search, an online questionnaire was produced. Secondly, 40 experts in the area of suicide postvention from English-speaking countries were recruited and asked to rate each action contained within this questionnaire, in terms of how important they felt it was to be included in the postvention guidelines. A set of guidelines was developed based on these responses. In total, panel members considered 965 actions across three consensus rounds. RESULTS: Five hundred fourty-eight actions were endorsed for inclusion into the postvention guidelines based on an 80% consensus agreement threshold. These actions were groups according to common themes, which are presented in the following sections: 1. Developing an Emergency Response Plan; 2. Forming an Emergency Response Team; 3. Activating the Emergency Response Team; 4. Managing a suspected suicide that occurs on school grounds; 5. Liaising with the deceased student's family; 6. Informing staff of the suicide; 7. Informing students of the suicide; 8. Informing parents of the suicide; 9. Informing the wider community of the suicide; 10. Identifying and supporting high-risk students; 11. Ongoing support of students; 12. Ongoing support of staff; 13. Dealing with the media; 14. Internet and social media; 15. The deceased student's belongings; 16. Funeral and memorial; 17. Continued monitoring of students and staff; 18. Documentation; 19. Critical Incident Review and annual review of the ER Plan; 20. Future prevention. Panel members frequently commented on every suicide being 'unique', and the need for flexibility in the guidelines, in order to accommodate the resources available, and the culture of the school community. CONCLUSION: In order to respond effectively and safely to the suicide of a student, schools need to undertake a variety of postvention actions. These are the first set of postvention guidelines produced worldwide for secondary schools that are based on expert opinion using the Delphi method.

Mechanisms of Visceral Organ Crosstalk: Importance of Alterations in Permeability in Rodent Models.

PURPOSE: The pathophysiology of painful bladder syndrome is poorly understood. However, there is evidence of female predominance and comorbidity with irritable bowel syndrome. Our hypothesis is that cross-sensitization between bladder and colon is due to altered permeability in 1 organ, which affects the other organ. MATERIALS AND METHODS: Experiments were performed in anesthetized, ovariectomized female rats. In separate groups protamine sulfate was infused in the bladder or trinitrobenzene sulfonic acid was infused in the colon. Untreated rats served as controls. Bladder and colonic tissue were harvested from all rats 1, 3 and 5 days after treatment. Permeability was assessed in vitro in Ussing chambers by measuring transepithelial electrical resistance and macromolecular flux of fluorescein isothiocyanate-dextran. RESULTS: Exposing the bladder to protamine sulfate induced a significant decrease in bladder transepithelial electrical resistance and an increase in the translocation of fluorescein isothiocyanate across the tissue compared to controls at 1 and 3 days (p <0.05). Colonic tissue from rats with enhanced bladder permeability showed a significant decrease in transepithelial electrical resistance and increase in fluorescein isothiocyanate compared to untreated controls at all time points (p <0.05). Conversely when colonic permeability was increased with trinitrobenzene sulfonic acid, we observed an increase in bladder permeability in the absence of any changes to the bladder urothelium. CONCLUSIONS: Changes in epithelial permeability may represent a novel mechanism for visceral organ crosstalk. It may explain the overlapping symptomology of painful bladder syndrome and irritable bowel syndrome.

Left ventricular assist device implantation outcomes in patients with subcutaneous implantable cardioverter-defibrillators: A case series.

Background: Left ventricular assist devices (LVADs) may induce electromagnetic interference (EMI) affecting implanted cardiac devices, including more novel subcutaneous implantable cardiac defibrillators (S-ICDs). Methods: In this case series, the authors retrospectively reviewed courses of 6 patients with S-ICDs who underwent LVAD implantation at a single center. Results: Of the 6 patients reviewed, 4 experienced inappropriate ICD shocks, of which 3 resulted from EMI. Five of the 6 patients ultimately had S-ICD therapies disabled. Conclusions: Due to EMI resulting in inappropriate shocks and improved tolerability of malignant arrhythmias, deactivation or removal of S-ICDs should be considered in patients undergoing LVAD implantation.