High-Dimensional Single-Cell Multimodal Landscape of Human Carotid Atherosclerosis.

BACKGROUND: Atherosclerotic plaques are complex tissues composed of a heterogeneous mixture of cells. However, our understanding of the comprehensive transcriptional and phenotypic landscape of the cells within these lesions is limited. METHODS: To characterize the landscape of human carotid atherosclerosis in greater detail, we combined cellular indexing of transcriptomes and epitopes by sequencing and single-cell RNA sequencing to classify all cell types within lesions (n=21; 13 symptomatic) to achieve a comprehensive multimodal understanding of the cellular identities of atherosclerosis and their association with clinical pathophysiology. RESULTS: We identified 25 cell populations, each with a unique multiomic signature, including macrophages, T cells, NK (natural killer) cells, mast cells, B cells, plasma cells, neutrophils, dendritic cells, endothelial cells, fibroblasts, and smooth muscle cells (SMCs). Among the macrophages, we identified 2 proinflammatory subsets enriched in IL-1B (interleukin-1B) or C1Q expression, 2 TREM2-positive foam cells (1 expressing inflammatory genes), and subpopulations with a proliferative gene signature and SMC-specific gene signature with fibrotic pathways upregulated. Further characterization revealed various subsets of SMCs and fibroblasts, including SMC-derived foam cells. These foamy SMCs were localized in the deep intima of coronary atherosclerotic lesions. Utilizing cellular indexing of transcriptomes and epitopes by sequencing data, we developed a flow cytometry panel, using cell surface proteins CD29, CD142, and CD90, to isolate SMC-derived cells from lesions. Lastly, we observed reduced proportions of efferocytotic macrophages, classically activated endothelial cells, and contractile and modulated SMC-derived cells, while inflammatory SMCs were enriched in plaques of clinically symptomatic versus asymptomatic patients. CONCLUSIONS: Our multimodal atlas of cell populations within atherosclerosis provides novel insights into the diversity, phenotype, location, isolation, and clinical relevance of the unique cellular composition of human carotid atherosclerosis. These findings facilitate both the mapping of cardiovascular disease susceptibility loci to specific cell types and the identification of novel molecular and cellular therapeutic targets for the treatment of the disease.

A short mindfulness induction might increase women's mental rotation performance.

The study aimed to investigate the effects of an embodied mindfulness treatment on chronometric mental rotation. Forty-four women and 47 men participated and were randomly divided into two groups: a mindfulness induction group and a control group. They completed two sets of 150 mental rotation tasks with cube figures each. Subjective cognitive effort (measured after each block), reaction time, and accuracy were analyzed using linear mixed models with the factors of time, mindfulness, angular disparity, and gender. The significant finding was a three-way interaction between pre-post testing, mindfulness, and gender for reaction times. This interaction suggests that women might benefit more from the mindfulness induction, while men may benefit more from the control condition. The analysis of subjective cognitive effort indicates that women and men perceive the same cognitive effort when solving cube-figure tasks.

The structure of ice under confinement in periodic mesoporous organosilicas (PMOs).

We investigated the structure of ice under nanoporous confinement in periodic mesoporous organosilicas (PMOs) with different organic functionalities and pore diameters between 3.4 and 4.9 nm. X-ray scattering measurements of the system were performed at temperatures between 290 and 150 K. We report the emergence of ice I with both hexagonal and cubic characteristics in different porous materials, as well as an alteration of the lattice parameters when compared to bulk ice. This effect is dependent on the pore diameter and the surface chemistry of the respective PMO. Investigations regarding the orientation of hexagonal ice crystals relative to the pore wall using x-ray cross correlation analysis reveal one or more discrete preferred orientation in most of the samples. For a pore diameter of around 3.8 nm, stronger correlation peaks are present in more hydrophilically functionalized pores and seem to be connected to stronger shifts in the lattice parameters.

General quasi-equilibrium multivalent binding model to study diverse and complex drug-receptor interactions of biologics.

Pharmacokinetics and pharmacodynamics of many biologics are influenced by their complex binding to biological receptors. Biologics consist of diverse groups of molecules with different binding kinetics to its receptors including IgG with simple one-to-one drug receptor bindings, bispecific antibody (BsAb) that binds to two different receptors, and antibodies that can bind to six or more identical receptors. As the binding process is typically much faster than elimination (or internalization) and distribution processes, quasi-equilibrium (QE) binding models are commonly used to describe drug-receptor binding kinetics of biologics. However, no general QE modeling framework is available to describe complex binding kinetics for diverse classes of biologics. In this paper, we describe novel approaches of using differential algebraic equations (DAE) to solve three QE multivalent drug-receptor binding (QEMB) models. The first example describes the binding kinetics of three-body equilibria of BsAb that binds to 2 different receptors for trimer formation. The second example models an engineered IgG variant (Multabody) that can bind to 24 identical target receptors. The third example describes an IgG with modified neonatal Fc receptor (FcRn) binding affinity that competes for the same FcRn receptor as endogenous IgG. The model parameter estimates were obtained by fitting the model to all data simultaneously. The models allowed us to study potential roles of cooperative binding on bell-shaped drug exposure-response relationships of BsAb, and concentration-depended distribution of different drug-receptor complexes for Multabody. This DAE-based QEMB model platform can serve as an important tool to better understand complex binding kinetics of diverse classes of biologics.

The role of extracellular structures in Clostridioides difficile biofilm formation.

C. difficile infection (CDI) is a costly and increasing burden on the healthcare systems of many developed countries due to the high rates of nosocomial infections. Despite the availability of several antibiotics with high response rates, effective treatment is hampered by recurrent infections. One potential mechanism for recurrence is the existence of C. difficile biofilms in the gut which persist through the course of antibiotics. In this review, we describe current developments in understanding the molecular mechanisms by which C. difficile biofilms form and are stabilized through extracellular biomolecular interactions.

ADAMTS7: a Novel Therapeutic Target in Atherosclerosis.

PURPOSE OF REVIEW: Genome-wide association studies have repeatedly linked the metalloproteinase ADAMTS7 to coronary artery disease. Here we aim to highlight recent findings surrounding the human genetics of ADAMTS7, novel mouse models that investigate ADAMTS7 function, and potential substrates of ADAMTS7 cleavage. RECENT FINDINGS: Recent genome-wide association studies in coronary artery disease have replicated the GWAS signal for ADAMTS7 and shown that the signal holds true even across different ethnic groups. However, the direction of effect in humans remains unclear. A recent novel mouse model revealed that the proatherogenicity of ADAMTS7 is derived from its catalytic functions, while at the translational level, vaccinating mice against ADAMTS7 reduced atherosclerosis. Finally, in vitro proteomics approaches have identified extracellular matrix proteins as candidate substrates that may be causal for the proatherogenicity of ADAMTS7. ADAMTS7 represents an enticing target for therapeutic intervention. The recent studies highlighted here have replicated prior findings, confirming the genetic link between ADAMTS7 and atherosclerosis, while providing further evidence in mice that ADAMTS7 is a targetable proatherogenic enzyme.

Oxidation-Dependent Activation of Src Kinase Mediates Epithelial IL-33 Production and Signaling during Acute Airway Allergen Challenge.

The respiratory epithelium forms the first line of defense against inhaled pathogens and acts as an important source of innate cytokine responses to environmental insults. One critical mediator of these responses is the IL-1 family cytokine IL-33, which is rapidly secreted upon acute epithelial injury as an alarmin and induces type 2 immune responses. Our recent work highlighted the importance of the NADPH oxidase dual oxidase 1 (DUOX1) in acute airway epithelial IL-33 secretion by various airborne allergens associated with H2O2 production and reduction-oxidation-dependent activation of Src kinases and epidermal growth factor receptor (EGFR) signaling. In this study, we show that IL-33 secretion in response to acute airway challenge with house dust mite (HDM) allergen critically depends on the activation of Src by a DUOX1-dependent oxidative mechanism. Intriguingly, HDM-induced epithelial IL-33 secretion was dramatically attenuated by small interfering RNA- or Ab-based approaches to block IL-33 signaling through its receptor IL1RL1 (ST2), indicating that HDM-induced IL-33 secretion includes a positive feed-forward mechanism involving ST2-dependent IL-33 signaling. Moreover, activation of type 2 cytokine responses by direct airway IL-33 administration was associated with ST2-dependent activation of DUOX1-mediated H2O2 production and reduction-oxidation-based activation of Src and EGFR and was attenuated in Duox1 -/- and Src +/- mice, indicating that IL-33-induced epithelial signaling and subsequent airway responses involve DUOX1/Src-dependent pathways. Collectively, our findings suggest an intricate relationship between DUOX1, Src, and IL-33 signaling in the activation of innate type 2 immune responses to allergens, involving DUOX1-dependent epithelial Src/EGFR activation in initial IL-33 secretion and in subsequent IL-33 signaling through ST2 activation.

Computing optimal drug dosing with OptiDose: implementation in NONMEM.

Determining a drug dosing recommendation with a PKPD model can be a laborious and complex task. Recently, an optimal dosing algorithm (OptiDose) was developed to compute the optimal doses for any pharmacometrics/PKPD model for a given dosing scenario. In the present work, we reformulate the underlying optimal control problem and elaborate how to solve it with standard commands in the software NONMEM. To demonstrate the potential of the OptiDose implementation in NONMEM, four relevant but substantially different optimal dosing tasks are solved. In addition, the impact of different dosing scenarios as well as the choice of the therapeutic goal on the computed optimal doses are discussed.

Survival dependence of 3D-printed temporary materials on the filler content.

AIM: The aim of the present study was the evaluation of the in vitro performance and fracture force of 3D-printed anterior implant-supported temporary partial dentures (TPDs) with different filler content. MATERIALS AND METHODS: Identical anterior resin-based TPDs (tooth sites 11 to 13; n = eight per material) were 3D printed from methacrylate resins with different filler content. A cartridge polymethyl methacrylate (PMMA) material was used as a reference. After temporary cementation, combined thermal cycling and mechanical loading (TCML) was performed on all the restorations to mimic clinical application. Behavior during TCML and fracture force was determined, and failures were analyzed. Data were statistically investigated (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, Kaplan-Meier survival; α = 0.05). RESULTS: Failure during TCML varied between three failures and total failure during loading time. Mean survival time varied between 93 ± 206 x 103 cycles and 329 ± 84 x 103 cycles. Significantly different survival cycles between the individual materials could be determined (Mantel Cox log-rank test: chi-square: 21,861; degrees of freedom (df) = 4, P < 0.001). A correlation between filler level and survival cycles could be found (Pearson: 0.186, P = 0.065). Fracture values of the surviving TPDs varied between 499 and 835 N. Failures were characterized by fracture of the connector (n = 24) followed by fractures at the abutment (n = 10). CONCLUSIONS: TDPs showed different filler-dependent survival. Individual 3D-printed materials provided comparable or even better performance than a standard cartridge system and might be sufficient for temporary application of at least half a year.

Genetic and Epigenetic Fine Mapping of Complex Trait Associated Loci in the Human Liver.

Deciphering the impact of genetic variation on gene regulation is fundamental to understanding common, complex human diseases. Although histone modifications are important markers of gene regulatory elements of the genome, any specific histone modification has not been assayed in more than a few individuals in the human liver. As a result, the effects of genetic variation on histone modification states in the liver are poorly understood. Here, we generate the most comprehensive genome-wide dataset of two epigenetic marks, H3K4me3 and H3K27ac, and annotate thousands of putative regulatory elements in the human liver. We integrate these findings with genome-wide gene expression data collected from the same human liver tissues and high-resolution promoter-focused chromatin interaction maps collected from human liver-derived HepG2 cells. We demonstrate widespread functional consequences of natural genetic variation on putative regulatory element activity and gene expression levels. Leveraging these extensive datasets, we fine-map a total of 74 GWAS loci that have been associated with at least one complex phenotype. Our results reveal a repertoire of genes and regulatory mechanisms governing complex disease development and further the basic understanding of genetic and epigenetic regulation of gene expression in the human liver tissue.

Efficacy and safety of oral semaglutide by subgroups of patient characteristics in the PIONEER phase 3 programme.

AIMS: To evaluate the efficacy and safety of oral semaglutide versus comparators by patient characteristic subgroups in patients with type 2 diabetes. MATERIALS AND METHODS: Change from baseline in glycated haemoglobin (HbA1c) and body weight, and achievement of HbA1c <7.0% with oral semaglutide 7 mg, oral semaglutide 14 mg, flexibly dosed oral semaglutide (flex) and comparators were assessed across baseline subgroups (age, race, ethnicity, diabetes duration, body mass index and HbA1c) from the PIONEER programme. Treatment differences were analysed using a mixed model for repeated measurements for continuous variables and a logistic regression model for the binary endpoint. Pooled safety data were analysed descriptively. RESULTS: Changes from baseline in HbA1c and body weight, and the odds of achieving HbA1c <7.0%, were greater with oral semaglutide 14 mg/flex (n = 1934) and higher or similar with oral semaglutide 7 mg (n = 823) versus comparators (n = 2077) across most subgroups. Changes in HbA1c with oral semaglutide 14 mg/flex were greater for patients with higher baseline HbA1c (HbA1c >9.0%: -1.7% to -2.6%; HbA1c <8.0%: -0.7% to -1.2%). In some trials, Asian patients experienced greater HbA1c reductions with oral semaglutide 14 mg/flex (-1.5% to -1.8%) than other racial groups (-0.6% to -1.6%). The overall incidence of adverse events (AEs) with oral semaglutide was similar to that with comparators and was consistent across subgroups. More gastrointestinal AEs were observed with oral semaglutide, versus comparators, across subgroups. CONCLUSIONS: Oral semaglutide demonstrated consistently greater HbA1c and body weight reductions across a range of patient characteristics, with greater HbA1c reductions seen at higher baseline HbA1c levels.

Building Your Mentoring Network in Your Early Career.

The pursuit of knowledge, curiosity about the natural world, and a drive to better the human condition are several of the many motivations that encourage someone to further their education in the biological sciences. However noble the intentions, success in an academic graduate program, and perhaps more importantly, in the career options that follow, is not guaranteed. While it is often said that a trainee needs support from their mentors and network to succeed, the Arteriosclerosis, Thrombosis and Vascular Biology Early Career Committee has observed, through our many interactions, both face to face and in the virtual space, that many trainees do not appreciate that building their mentoring network is an active process, and the trainee has more agency in the relationship than perhaps they perceive. In the article below, we discuss our views on building relationships and identifying mentors at different levels and for different purposes. We also highlight events hosted by the Arteriosclerosis, Thrombosis and Vascular Biology Early Career Committee at Vascular Discoveries, Scientific Sessions, and in the virtual space that can help you at the critical career stage.

Pupillometry as a measure of cognitive load in mental rotation tasks with abstract and embodied figures.

We investigated sex differences in behavioral performance and cognitive load in chronometric mental rotation tasks with abstract and embodied figures. Eighty participants (44 females and 36 males) completed 126 items, which included cube figures, body postures, and human figures, which were all comparable in shape and color. Reaction time, accuracy, and cognitive load, measured by changes in pupil dilation, were analyzed. As a function of angular disparity, participants showed shorter reaction times and higher accuracy rates for embodied stimuli than cube figures. Changes in pupil dilation showed a similar pattern, indicating that mental rotation of embodied figures caused less cognitive load to solve the task. No sex differences appeared in any of the measurements.

Competing tissue-specific functions for the Tribbles-1 plasma lipid associated locus.

PURPOSE OF REVIEW: The pseudokinase Tribbles-1 (TRIB1) remains the focus of intense research since genome-wide association studies (GWAS) associated it with multiple cardiometabolic traits in humans, including plasma lipids and atherosclerosis. This review highlights recent advances in understanding the function of TRIB1 and what outstanding questions remain. RECENT FINDINGS: Studies performed in a myeloid-specific Trib1 mouse model show that Trib1 contributes to foam cell formation, underscoring the importance of continued research into tissue-specific functions of TRIB1. Investigations of TRIB1 function in a 3D hepatic organoid model demonstrate that hepatic TRIB1 functions elucidated in mouse models are recapitulated in these organoid systems. Lastly, a recent study showed berberine, an existing lipid-lowering drug, to be acting via a TRIB1-dependent mechanism, highlighting both a novel regulator of TRIB1 expression and the potential of studying TRIB1 through existing therapeutics. SUMMARY: TRIB1 remains one of the more fascinating loci to arise from cardiometabolic GWAS, given the constellation of traits it associates with. As genetic studies continue to link TRIB1 to metabolic phenotypes, more functional research on tissue-specific TRIB1, regulation of TRIB1 and its function in current therapies, as well as the reproduction of results from mice in human contexts are all necessary to increase our understanding of TRIB1 and its relevance.

Endothelial Foxp1 Suppresses Atherosclerosis via Modulation of Nlrp3 Inflammasome Activation.

RATIONALE: Endothelial dysfunction results in sustained and chronic vascular inflammation, which is central to atherosclerotic diseases. However, transcriptional regulation of vascular endothelial inflammation has not been well clarified. OBJECTIVE: This study aims to explore Foxp (forkhead box P) transcription factor 1 in regulation of endothelial homeostasis, atherogenesis, and its mechanisms. METHODS AND RESULTS: To assess the importance of Foxp1 in atherosclerosis, Foxp1 expression was analyzed in human coronary artery and mouse artery, and we observed significant downregulation of Foxp1 in atherosclerotic and atherosusceptible endothelium. Endothelial-specific Foxp1 knockout mice (Foxp1ECKO) were bred onto ApoeKO mice to generate endothelial Foxp1-deletion hyperlipidemic model Foxp1ECKO;ApoeKO, which displayed significant increases in atherosclerotic lesion formation in aortas and aortic roots with enhanced monocyte adhesion, migration, and infiltration into the vascular wall and formation of inflammatory lipid-laden macrophages. In contrast, endothelial-specific Foxp1 overexpression mice Foxp1ECTg;ApoeKO exhibited reduced atherosclerotic lesion formation with less monocyte infiltration. Foxp1 was further identified as a gatekeeper of vessel inflammation by direct regulation of endothelial inflammasome components, including Nlrp3 (NLR [nucleotide-binding and leucine-rich repeat immune receptors] family pyrin domain containing 3), caspase-1, and IL (interleukin)-1ß. Moreover, endothelial Foxp1 was found to be regulated by Klf2 (Kruppel-like factor 2). Oscillatory shear stress downregulated Foxp1 expression via repressing Klf2 expression in endothelium, and, therefore, promoted endothelial inflammasome activation, leading to atherosclerotic lesion formation. Simvastatin upregulated the reduced expression of Klf2 and Foxp1 in atherosusceptible vascular endothelium and alleviated vascular inflammation contributing to its inhibitory effect in atherosclerosis. CONCLUSIONS: These data are the first in vivo experimental validation of an atheroprotective role of endothelial Klf2 and Foxp1, which reveals a Klf2-Foxp1 transcriptional network in endothelial cells as a novel regulator of endothelial inflammasome activation for atherogenesis, therefore, provides opportunities for therapeutic intervention of atherosclerotic diseases and uncovers a novel atheroprotective mechanism for simvastatin.

Effects of oral semaglutide on energy intake, food preference, appetite, control of eating and body weight in subjects with type 2 diabetes.

AIM: To evaluate the effect of oral semaglutide on energy intake and appetite in subjects with type 2 diabetes (T2D). MATERIALS AND METHODS: In this randomized, double-blind, placebo-controlled, two-period cross-over trial, 15 subjects with T2D received 12 weeks of treatment with once-daily oral semaglutide (4-week dose escalation from 3 to 7 to 14 mg) followed by placebo, or vice versa. Energy intake was measured during an ad libitum lunch, evening meal and snack box after a standard breakfast. Appetite ratings were measured using a visual analogue scale after standard and fat-rich breakfasts. Other assessments included eating and craving control (using the Control of Eating Questionnaire), and changes in body weight and composition. RESULTS: Following a standard breakfast, total daily ad libitum energy intake was significantly lower (38.9%) with oral semaglutide versus placebo in 13 evaluable subjects (estimated treatment difference, -5096.0 kJ; 95% CI -7000.0, -3192.1; P = .0001). After a fat-rich breakfast, there were significant differences in favour of oral semaglutide versus placebo for measures of satiety, hunger and for overall appetite score, with no significant differences following a standard breakfast. Fewer food cravings and better eating control were seen with oral semaglutide versus placebo. Overall, mean body weight decreased by 2.7 kg with oral semaglutide and 0.1 kg with placebo, mostly attributable to body fat mass loss. CONCLUSION: After 12 weeks of treatment, ad libitum energy intake was lower with oral semaglutide versus placebo, resulting in reduced body fat mass, and was associated with increased satiety and fullness after a fat-rich breakfast, and improved eating control. TRIAL REGISTRATION NUMBER: NCT02773381.

Delay differential equations based models in NONMEM.

Delay differential equations (DDEs) are commonly used in pharmacometric models to describe delays present in pharmacokinetic and pharmacodynamic data analysis. Several DDE solvers have been implemented in NONMEM 7.5 for the first time. Two of them are based on algorithms already applied elsewhere, while others are extensions of existing ordinary differential equations (ODEs) solvers. The purpose of this tutorial is to introduce basic concepts underlying DDE based models and to show how they can be developed using NONMEM. The examples include previously published DDE models such as logistic growth, tumor growth inhibition, indirect response with precursor pool, rheumatoid arthritis, and erythropoiesis-stimulating agents. We evaluated the accuracy of NONMEM DDE solvers, their ability to handle stiff problems, and their performance in parameter estimation using both first-order conditional estimation (FOCE) and the expectation-maximization (EM) method. NONMEM control streams and excerpts from datasets are provided for all discussed examples. All DDE solvers provide accurate and precise solutions with the number of significant digits controlled by the error tolerance parameters. For estimation of population parameters, the EM method is more stable than FOCE regardless of the DDE solver.

Surrogate endpoint evaluation using data from one large global randomized controlled trial.

BACKGROUND: Robust identification of surrogate endpoints can help accelerate the development of pharmacotherapies for diseases traditionally evaluated using true endpoints associated with prolonged follow-up. The meta-analysis-based surrogate endpoint evaluation (SEE) integrates data from multiple, usually smaller, trials to statistically confirm a surrogate endpoint as a robust proxy for the true endpoint. To test the applicability of SEE when only a single, larger trial is available, we analysed the cardiovascular (CV) survival endpoint from the large multinational trial LEADER (9340 subjects) that confirmed the CV safety of a diabetes drug (liraglutide). We evaluated if using country as a trial unit adequately facilitated the meta-analysis and calculation of R2 by country group. METHODS: Data were grouped by country, ensuring at least 30 CV deaths (497 in total) in each of the nine resulting by-country groups. In a two-step SEE on the grouped dataset, we first fitted the group-specific Cox proportional hazard models; next, on the trial-level, we regressed the estimated hazard ratio (HR; liraglutide vs placebo) of the true endpoints (CV death: 497 events, or all-cause death: 828 events) on the HR of the surrogate endpoint (major CV adverse event [MACE]: 1302 events) and derived the group-specific R2 and its 95% confidence interval (CI). RESULTS: Group-level surrogacy of MACE was supported for CV death but not for all-cause death, with [Formula: see text] values of 0.85 [0.63;1.00]95% CI and 0.23 [0.00;0.67]95% CI, respectively. Sensitivity analyses using different grouping approaches (e.g. grouping by region) corroborated the robustness of the conclusions as well as the appropriateness of the data-grouping approaches. CONCLUSIONS: We derived a specific grouping approach to successfully apply SEE on data from a single trial. This may allow for the statistically robust identification and validation of surrogate endpoints based on the abundance of large monolithic outcome trials conducted as part of drug development programmes in, for example, diabetes.

In vitro performance and fracture resistance of interim conventional or CAD-CAM implant-supported screw- or cement-retained anterior fixed partial dentures.

STATEMENT OF PROBLEM: Interim restorations represent an essential clinical treatment step; however, limited information is available concerning the performance of computer-aided design and computer-aided manufacturing (CAD-CAM) interim materials. PURPOSE: The purpose of this in vitro study was to evaluate the performance and fracture load of resin anterior implant-supported interim fixed partial dentures (IFPDs). MATERIAL AND METHODS: Identical anterior resin IFPDs (maxillary central incisor to canine; n=16 per material) were milled from polymethylmethacrylate (PMMA) or di-methacrylate (DMA) systems with different filler content. The IFPD groups were split to simulate a chairside (cemented implant-supported prosthesis) or laboratory procedure (screw-retained implant-supported prosthesis). A cartridge DMA material served as a control. After interim cementation, combined thermocycling and mechanical loading (TCML) was performed on all restorations to approximate a maximum of 2.5 years of clinical function. Behavior during TCML and fracture force was determined, and failures were analyzed. The data were statistically investigated (Kolmogorov-Smirnov test, 1-way-ANOVA; post hoc Bonferroni, Kaplan-Meier survival, α=.05). RESULTS: Drop out during TCML varied between no failures and complete failure during loading. For most systems, failure occurred between 120 000 and 600 000 mechanical loading cycles. For IFPDs without a screw channel fracture, values varied between 644 ±263 N and 987 ±101 N. Those with a screw channel fracture failed between 493 ±89 N and 951 ±248 N. Individual IFPDs had significantly higher mean fracture loads (P<.002), but the mean fracture values between IFPDs with and without a screw channel were not significantly different (P>.137). Failures were characterized by fracture of the connector (n=53) followed by mixed failures (n=22) or fractures at the abutment (n=21). CONCLUSIONS: These interim materials are sufficiently fracture resistant for the fabrication of implant-supported anterior IFPDs and are expected to survive between 6 months and 2 years before failure. The stability of IFPDs depended on the type of material but not on the restoration design (with or without a screw channel).