In AF, the effects of DOACs vs. warfarin on death and stroke/systemic embolism vary by baseline CrCl level.

SOURCE CITATION: Harrington J, Carnicelli AP, Hua K, et al. Direct oral anticoagulants versus warfarin across the spectrum of kidney function: patient-level network meta-analyses from COMBINE AF. Circulation. 2023;147:1748-1757. 37042255.

In healthy older adults, low-dose aspirin increased incident anemia at a median 4.7 y.

SOURCE CITATION: McQuilten ZK, Thao LT, Pasricha SR, et al. Effect of low-dose aspirin versus placebo on incidence of anemia in the elderly: a secondary analysis of the Aspirin in Reducing Events in the Elderly trial. Ann Intern Med. 2023;176:913-921. 37335992.

The clot thickens-enhanced integration of stroke and thrombosis training.

There is significant overlap between knowledge and its clinical application in stroke and thrombosis & vascular medicine. Formal integration of training is, however, not standard. After the hyperacute phase of management, personalized medical decisions are often needed regarding antithrombotics and anticoagulants that leverage clinical practice parameters from both disciplines with a unique emphasis on minimizing neurologic treatment complications. We completed an ad hoc survey of adult thrombosis fellowships at several North American centers. We discovered that direct integration of training programs is not prevalent, suggesting a role for more deliberate integration of training programs. We provide a framework and resources for consideration that directly improve, by design, integrated clinical experiences during training, harnessing the strengths in both stroke and thrombosis programs.

Characterization of the catalytic signature of Scabin toxin, a DNA-targeting ADP-ribosyltransferase.

Scabin was previously identified as a novel DNA-targeting mono-ADP-ribosyltransferase (mART) toxin from the plant pathogen 87.22 strain of Streptomyces scabies Scabin is a member of the Pierisin-like subgroup of mART toxins, since it targets DNA. An in-depth characterization of both the glycohydrolase and transferase enzymatic activities of Scabin was conducted. Several protein variants were developed based on an initial Scabin·DNA molecular model. Consequently, three residues were deemed important for DNA-binding and transferase activity. Trp128 and Trp155 are important for binding the DNA substrate and participate in the reaction mechanism, whereas Tyr129 was shown to be important only for DNA binding, but was not involved in the reaction mechanism. Trp128 and Trp155 are both conserved within the Pierisin-like toxins, whereas Tyr129 is a unique substitution within the group. Scabin showed substrate specificity toward double-stranded DNA containing a single-base overhang, as a model for single-stranded nicked DNA. The crystal structure of Scabin bound to NADH - a competitive inhibitor of Scabin - was determined, providing important insights into the active-site structure and Michaelis-Menten complex of the enzyme. Based on these results, a novel DNA-binding motif is proposed for Scabin with substrate and the key residues that may participate in the Scabin·NAD(+) complex are highlighted.

Scabin, a Novel DNA-acting ADP-ribosyltransferase from Streptomyces scabies.

A bioinformatics strategy was used to identify Scabin, a novel DNA-targeting enzyme from the plant pathogen 87.22 strain of Streptomyces scabies Scabin shares nearly 40% sequence identity with the Pierisin family of mono-ADP-ribosyltransferase toxins. Scabin was purified to homogeneity as a 22-kDa single-domain enzyme and was shown to possess high NAD(+)-glycohydrolase (Km (NAD) = 68 ± 3 µm; kcat = 94 ± 2 min(-1)) activity with an RSQXE motif; it was also shown to target deoxyguanosine and showed sigmoidal enzyme kinetics (K0.5(deoxyguanosine) = 302 ± 12 µm; kcat = 14 min(-1)). Mass spectrometry analysis revealed that Scabin labels the exocyclic amino group on guanine bases in either single-stranded or double-stranded DNA. Several small molecule inhibitors were identified, and the most potent compounds were found to inhibit the enzyme activity with Ki values ranging from 3 to 24 µm PJ34, a well known inhibitor of poly-ADP-ribosyltransferases, was shown to be the most potent inhibitor of Scabin. Scabin was crystallized, representing the first structure of a DNA-targeting mono-ADP-ribosyltransferase enzyme; the structures of the apo-form (1.45 Å) and with two inhibitors (P6-E, 1.4 Å; PJ34, 1.6 Å) were solved. These x-ray structures are also the first high resolution structures of the Pierisin subgroup of the mono-ADP-ribosyltransferase toxin family. A model of Scabin with its DNA substrate is also proposed.

Factor XI inhibition in cardiovascular disease.

Cardiovascular disease remains the leading cause of mortality worldwide, with the World Health Organization estimating 17.9 million attributable deaths each year. Anticoagulants are commonly used to prevent and treat thromboembolism but currently available agents, including heparins, fondaparinux, vitamin K antagonists (VKAs), and direct oral anticoagulants (DOACs) possess inherent bleeding risks which may limit or preclude their use in patients at highest risk of bleeding. The development of a new class of anticoagulants that target factor XI (FXI) has been hailed as a potential solution to mitigate bleeding while providing effective anticoagulation. In this paper, we examine the rationale for the development of anticoagulants that target FXI and their potential future role. Specifically, we review the agents currently under clinical investigation, the available evidence regarding their efficacy and safety, the implications of recent trial discontinuations, and unresolved issues.

Anticoagulation for stroke prevention in atrial fibrillation and treatment of venous thromboembolism and portal vein thrombosis in cirrhosis: guidance from the SSC of the ISTH.

While advanced liver disease was previously considered to be an acquired bleeding disorder, there is increasing recognition of an associated prothrombotic state with patients being at higher risk of atrial fibrillation (AF) and stroke and venous thromboembolism (VTE) including portal vein thrombosis (PVT). We review the available literature on epidemiology, pathophysiology, and risk factors and provide guidance on anticoagulant management of these conditions in adults with cirrhosis. In patients with Child-Pugh A or B cirrhosis and AF, we recommend anticoagulation with standard-dose direct oral anticoagulants (DOACs) in accordance with cardiology guideline recommendations for patients without liver disease. In those with Child-Pugh C cirrhosis, there is inadequate evidence with respect to the benefit and risk of anticoagulation for stroke prevention in AF. In patients with cirrhosis and acute deep vein thrombosis or pulmonary embolism, we recommend anticoagulation and suggest use of either a DOAC or low-molecular-weight heparin (LMWH)/vitamin K antagonist (VKA) in Child-Pugh A or B cirrhosis and LMWH alone (or as a bridge to VKA in patients with a normal baseline international normalized ratio) in Child-Pugh C cirrhosis. We recommend anticoagulation for patients with cirrhosis and symptomatic PVT. We suggest anticoagulation for those with asymptomatic, progressing PVT and recommend continuing extended anticoagulation for liver transplant candidates with PVT.

Drug-drug interactions between direct oral anticoagulants and anticonvulsants and clinical outcomes: A systematic review.

Background: Direct oral anticoagulants (DOACs) are widely used in patients with atrial fibrillation and venous thromboembolism. However, DOACs have important potential drug-drug interactions (DDIs) with several classes of drugs. In particular, antiepileptic (AE) drugs may induce cytochrome P450 3A4 or P-glycoprotein. Co-administration of DOACs and AE drugs may result in lower DOAC drug levels and reduced DOAC efficacy. However, the clinical significance of such DDIs is uncertain. Objectives: The aim of this systematic review was to generate an updated review of these DDIs and their clinical relevance, given the rapidly evolving knowledge relating to DOAC and AE DDIs. Methods: We searched the MEDLINE and Embase databases for studies reporting clinical adverse outcomes (thrombotic events, bleeding events, and all-cause mortality) in patients concomitantly taking DOACs and AE drugs. Results: We retrieved 874 studies of which 15 were deemed eligible for this review, including 4 congress abstracts, 3 case reports, 2 letters to the editor, 5 retrospective cohorts, and 1 prospective cohort study. No randomized clinical trials were found. Most of the included studies reported thrombotic events, 3 studies reported major bleeding, and one study reported all-cause mortality associated with DOAC and AE drug administration. Substantial differences in the study designs did not allow for a meta-analysis to be performed. Conclusion: The current literature assessing these adverse clinical outcomes from DOAC and AE drug co-administration is limited. Although the available data point to a possible increased risk of thrombotic events, they are insufficient to draw definitive conclusions. Well-designed clinical studies are of utmost importance.

Dual pathway inhibition for atherosclerotic cardiovascular disease: Recent advances.

Atherosclerotic cardiovascular disease (ASCVD), which includes coronary artery disease (CAD), cerebrovascular disease, and peripheral arterial disease (PAD) is associated with significant morbidity, mortality, and healthcare costs. Antiplatelet therapy has long been the mainstay of antithrombotic therapy for the prevention of first-ever and recurrent ASCVD events. More recently, however, randomized trials have demonstrated the benefits and cost-effectiveness of a dual pathway inhibition (DPI) strategy in acute and chronic ASCVD. When used in combination, aspirin and low-dose rivaroxaban work synergistically to inhibit platelet activation and thrombin generation, thereby preventing thrombus formation. Among patients with recent acute coronary syndrome (ACS), those with positive cardiac biomarkers or ST-segment elevation myocardial infarction, or a history of heart failure derive the greatest absolute benefits. Among patients with chronic ASCVD, those with involvement of two or more vascular beds, heart failure, chronic kidney disease, or diabetes derive the greatest absolute benefits. Additional trials are underway to assess the impact of DPI therapy in other populations of interest, including patients with ACS at high risk of left ventricular thrombus formation, intracranial atherosclerotic disease with recent transient ischemic attack or stroke, peripheral arterial disease with limiting claudication or post lower extremity revascularization, and advanced chronic kidney disease with ASCVD or risk factors for ASCVD. Further work is required to assess the possible added benefit of combining rivaroxaban with clopidogrel or ticagrelor instead of aspirin.

De novo phosphatidylcholine synthesis in the small intestinal epithelium is required for normal dietary lipid handling and maintenance of the mucosal barrier.

Cytidine triphosphate:phosphocholine cytidylyltransferase-α (CTα) is the rate limiting enzyme in the major pathway for de novo phosphatidylcholine (PC) synthesis. When CTα is deleted specifically in intestinal epithelial cells of adult mice (CTαIKO mice) fed a high-fat diet they present with weight loss, lipid malabsorption, and high postprandial GLP-1 levels. The current study aimed to characterize the changes that occur in the small intestines of CTαIKO mice using transcriptomics and to determine whether intestinal function could be rescued in CTαIKO mice. We found that impaired de novo PC synthesis in the gut is linked to lower abundance of transcripts related to lipid metabolism and higher abundance of transcripts related to ER stress and cell death, together with loss of goblet cells from the small intestinal epithelium. Furthermore, impaired movement of fatty acids from the intestinal lumen into enterocytes was observed in isolated intestinal sacs derived from CTαIKO mice, a model that excludes factors such as bile, gastric emptying, the nervous system, and circulating hormones. Antibiotic treatment prevented acute weight loss and normalized jejunum TG concentrations after refeeding but did not prevent ER stress or loss of goblet cells in CTαIKO mice. Dietary PC supplementation partially prevented loss of goblet cells but was unable to normalize jejunal TG concentrations after refeeding in CTαIKO mice. High postprandial plasma GLP-1 levels were present in CTαIKO mice regardless of antibiotic treatment, dietary PC content, or dietary fat content. Together, these data show that there is a specific requirement from de novo PC synthesis in maintaining small intestinal homeostasis, including dietary lipid uptake, normal hormone secretion, and barrier function.

Direct oral anticoagulant dose selection: Challenging cases.

Direct oral anticoagulants (DOACs) are given in fixed doses without routine laboratory monitoring of their anticoagulant effect based on the results of pivotal phase III trials. In some of these trials, patients were randomly allocated to receive a higher or lower dose of a DOAC, whereas in others, most patients were given a standard dose and only a subset deemed to be at risk of drug accumulation was given a lower dose. Treatment guidelines recommend dosing DOACs according to the way that they were tested in the trials, but for some patients, the optimal dosing remains uncertain. One example is patients with atrial fibrillation who are thought to have an unacceptably high risk of bleeding but do not meet the guideline criteria for dose reduction. A second is patients with venous thromboembolism who have completed 3 to 6 months of anticoagulation and are eligible for extended treatment with a standard or reduced dose of DOAC. In this review, we present a case-based approach to DOAC dose selection in these two settings.

Initiation of anticoagulation in atrial fibrillation by primary care physicians: Results of a telephone survey.

BACKGROUND: Direct oral anticoagulants (DOACs) are prescribed for over 80% of patients who start anticoagulant therapy for a new diagnosis of atrial fibrillation (AF). Inappropriate DOAC prescriptions are associated with increased mortality. However, limited data exist as to what proportion of primary care physicians (PCPs) initiate anticoagulation in patients with new AF and the extent of their DOAC knowledge. MATERIAL AND METHODS: We conducted a telephone survey of randomly selected PCPs in Ontario, Canada. Our primary objective was to determine the percentage of PCPs who initiate anticoagulation in new AF patients and the proportion of patients they initiate on DOACs. Our secondary objectives were to assess PCPs' knowledge about DOACs and to identify educational opportunities to address any knowledge gaps. RESULTS: Our survey included 50 respondents. After making a new AF diagnosis, 66% of PCPs stated that they usually initiate anticoagulation themselves and 84% prescribed a DOAC at least 75% of the time. Potential DOAC knowledge gaps included: administration considerations, off-label dosing, concomitant use of acetylsalicylic acid (ASA) in stable coronary artery disease (CAD) and use in valvular AF. CONCLUSION: Most PCPs initiate anticoagulants for AF and prescribe DOACs for the vast majority of new patients. PCPs were well versed in certain aspects of DOAC prescribing, however, a number of knowledge gaps were identified. PCPs may benefit from targeted education in these areas to improve patient outcomes in AF.

Mild Choline Deficiency and MTHFD1 Synthetase Deficiency Interact to Increase Incidence of Developmental Delays and Defects in Mice.

Folate and choline are interconnected metabolically. The MTHFD1 R653Q SNP is a risk factor for birth defects and there are concerns that choline deficiency may interact with this SNP and exacerbate health risks. 80-90% of women do not meet the Adequate Intake (AI) for choline. The objective of this study was to assess the effects of choline deficiency on maternal one-carbon metabolism and reproductive outcomes in the MTHFD1-synthetase deficient mouse (Mthfd1S), a model for MTHFD1 R653Q. Mthfd1S+/+ and Mthfd1S+/- females were fed control (CD) or choline-deficient diets (ChDD; 1/3 the amount of choline) before mating and during pregnancy. Embryos were evaluated for delays and defects at 10.5 days gestation. Choline metabolites were measured in the maternal liver, and total folate measured in maternal plasma and liver. ChDD significantly decreased choline, betaine, phosphocholine, and dimethylglycine in maternal liver (p < 0.05, ANOVA), and altered phosphatidylcholine metabolism. Maternal and embryonic genotype, and diet-genotype interactions had significant effects on defect incidence. Mild choline deficiency and Mthfd1S+/- genotype alter maternal one-carbon metabolism and increase incidence of developmental defects. Further study is required to determine if low choline intakes contribute to developmental defects in humans, particularly in 653QQ women.

Intestinal Phospholipid Disequilibrium Initiates an ER Stress Response That Drives Goblet Cell Necroptosis and Spontaneous Colitis in Mice.

BACKGROUND & AIMS: Patients with ulcerative colitis have low concentrations of the major membrane lipid phosphatidylcholine (PC) in gastrointestinal mucus, suggesting that defects in colonic PC metabolism might be involved in the development of colitis. To determine the precise role that PC plays in colonic barrier function, we examined mice with intestinal epithelial cell (IEC)-specific deletion of the rate-limiting enzyme in the major pathway for PC synthesis: cytidine triphosphate:phosphocholine cytidylyltransferase-α (CTαIKO mice). METHODS: Colonic tissue of CTαIKO mice and control mice was analyzed by histology, immunofluorescence, electron microscopy, quantitative polymerase chain reaction, Western blot, and thin-layer chromatography. Histopathologic colitis scores were assigned by a pathologist blinded to the experimental groupings. Intestinal permeability was assessed by fluorescein isothiocyanate-dextran gavage and fecal microbial composition was analyzed by sequencing 16s ribosomal RNA amplicons. Subsets of CTαIKO mice and control mice were treated with dietary PC supplementation, antibiotics, or 4-phenylbutyrate. RESULTS: Inducible loss of CTα in the intestinal epithelium reduced colonic PC concentrations and resulted in rapid and spontaneous colitis with 100% penetrance in adult mice. Colitis development in CTαIKO mice was traced to a severe and unresolving endoplasmic reticulum stress response in IECs with altered membrane phospholipid composition. This endoplasmic reticulum stress response was linked to the necroptotic death of IECs, leading to excessive loss of goblet cells, formation of a thin mucus barrier, increased intestinal permeability, and infiltration of the epithelium by microbes. CONCLUSIONS: Maintaining the PC content of IEC membranes protects against colitis development in mice, showing a crucial role for IEC phospholipid equilibrium in colonic homeostasis. SRA accession number: PRJNA562603.

A Step-by-Step Guide to Building a Complex Care Coordination Program in a Small Setting.

Children with medical complexity comprise a growing population that stresses existing models of pediatric care. This report will describe a care support project that delivered shared plans of care to providers and families of children with medical complexity. This program was built around carefully constructed care support teams where each member had clearly defined roles and responsibilities. The teams worked collaboratively to improve provider communication, create SMART (Specific, Measurable, Assignable, Realistic, and Timely) goals, and perform task tracking. This process created a scaffolding to support community physicians, allowing patients to remain in their local medical homes and to access services closer to home and reducing hospital admissions and emergency room overutilization.