Prospective derivation of a living organoid biobank of colorectal cancer patients.

In Rspondin-based 3D cultures, Lgr5 stem cells from multiple organs form ever-expanding epithelial organoids that retain their tissue identity. We report the establishment of tumor organoid cultures from 20 consecutive colorectal carcinoma (CRC) patients. For most, organoids were also generated from adjacent normal tissue. Organoids closely recapitulate several properties of the original tumor. The spectrum of genetic changes within the "living biobank" agrees well with previous large-scale mutational analyses of CRC. Gene expression analysis indicates that the major CRC molecular subtypes are represented. Tumor organoids are amenable to high-throughput drug screens allowing detection of gene-drug associations. As an example, a single organoid culture was exquisitely sensitive to Wnt secretion (porcupine) inhibitors and carried a mutation in the negative Wnt feedback regulator RNF43, rather than in APC. Organoid technology may fill the gap between cancer genetics and patient trials, complement cell-line- and xenograft-based drug studies, and allow personalized therapy design. PAPERCLIP.

The Environmental Sensor AHR Protects from Inflammatory Damage by Maintaining Intestinal Stem Cell Homeostasis and Barrier Integrity.

The epithelium and immune compartment in the intestine are constantly exposed to a fluctuating external environment. Defective communication between these compartments at this barrier surface underlies susceptibility to infections and chronic inflammation. Environmental factors play a significant, but mechanistically poorly understood, role in intestinal homeostasis. We found that regeneration of intestinal epithelial cells (IECs) upon injury through infection or chemical insults was profoundly influenced by the environmental sensor aryl hydrocarbon receptor (AHR). IEC-specific deletion of Ahr resulted in failure to control C. rodentium infection due to unrestricted intestinal stem cell (ISC) proliferation and impaired differentiation, culminating in malignant transformation. AHR activation by dietary ligands restored barrier homeostasis, protected the stem cell niche, and prevented tumorigenesis via transcriptional regulation of of Rnf43 and Znrf3, E3 ubiquitin ligases that inhibit Wnt-ß-catenin signaling and restrict ISC proliferation. Thus, activation of the AHR pathway in IECs guards the stem cell niche to maintain intestinal barrier integrity.

Diabetes risk gene and Wnt effector Tcf7l2/TCF4 controls hepatic response to perinatal and adult metabolic demand.

Most studies on TCF7L2 SNP variants in the pathogenesis of type 2 diabetes (T2D) focus on a role of the encoded transcription factor TCF4 in ß cells. Here, a mouse genetics approach shows that removal of TCF4 from ß cells does not affect their function, whereas manipulating TCF4 levels in the liver has major effects on metabolism. In Tcf7l2(-/-) mice, the immediate postnatal surge in liver metabolism does not occur. Consequently, pups die due to hypoglycemia. By combining chromatin immunoprecipitation with gene expression profiling, we identify a TCF4-controlled metabolic gene program that is acutely activated in the postnatal liver. In concordance, adult liver-specific Tcf7l2 knockout mice show reduced hepatic glucose production during fasting and display improved glucose homeostasis when maintained on high-fat diet. Furthermore, liver-specific TCF4 overexpression increases hepatic glucose production. These observations imply that TCF4 directly activates metabolic genes and that inhibition of Wnt signaling may be beneficial in metabolic disease.

Wnt signaling through inhibition of ß-catenin degradation in an intact Axin1 complex.

Degradation of cytosolic ß-catenin by the APC/Axin1 destruction complex represents the key regulated step of the Wnt pathway. It is incompletely understood how the Axin1 complex exerts its Wnt-regulated function. Here, we examine the mechanism of Wnt signaling under endogenous levels of the Axin1 complex. Our results demonstrate that ß-catenin is not only phosphorylated inside the Axin1 complex, but also ubiquinated and degraded via the proteasome, all within an intact Axin1 complex. In disagreement with current views, we find neither a disassembly of the complex nor an inhibition of phosphorylation of Axin1-bound ß-catenin upon Wnt signaling. Similar observations are made in primary intestinal epithelium and in colorectal cancer cell lines carrying activating Wnt pathway mutations. Wnt signaling suppresses ß-catenin ubiquitination normally occurring within the complex, leading to complex saturation by accumulated phospho-ß-catenin. Subsequently, newly synthesized ß-catenin can accumulate in a free cytosolic form and engage nuclear TCF transcription factors.

ZAKß is activated by cellular compression and mediates contraction-induced MAP kinase signaling in skeletal muscle.

Mechanical inputs give rise to p38 and JNK activation, which mediate adaptive physiological responses in various tissues. In skeletal muscle, contraction-induced p38 and JNK signaling ensure adaptation to exercise, muscle repair, and hypertrophy. However, the mechanisms by which muscle fibers sense mechanical load to activate this signaling have remained elusive. Here, we show that the upstream MAP3K ZAKß is activated by cellular compression induced by osmotic shock and cyclic compression in vitro, and muscle contraction in vivo. This function relies on ZAKß's ability to recognize stress fibers in cells and Z-discs in muscle fibers when mechanically perturbed. Consequently, ZAK-deficient mice present with skeletal muscle defects characterized by fibers with centralized nuclei and progressive adaptation towards a slower myosin profile. Our results highlight how cells in general respond to mechanical compressive load and how mechanical forces generated during muscle contraction are translated into MAP kinase signaling.

Wnt and Src signals converge on YAP-TEAD to drive intestinal regeneration.

Wnt signalling induces a gradient of stem/progenitor cell proliferation along the crypt-villus axis of the intestine, which becomes expanded during intestinal regeneration or tumour formation. The YAP transcriptional co-activator is known to be required for intestinal regeneration, but its mode of regulation remains controversial. Here we show that the YAP-TEAD transcription factor is a key downstream effector of Wnt signalling in the intestine. Loss of YAP activity by Yap/Taz conditional knockout results in sensitivity of crypt stem cells to apoptosis and reduced cell proliferation during regeneration. Gain of YAP activity by Lats1/2 conditional knockout is sufficient to drive a crypt hyperproliferation response. In particular, Wnt signalling acts transcriptionally to induce YAP and TEAD1/2/4 expression. YAP normally localises to the nucleus only in crypt base stem cells, but becomes nuclear in most intestinal epithelial cells during intestinal regeneration after irradiation, or during organoid growth, in a Src family kinase-dependent manner. YAP-driven crypt expansion during regeneration involves an elongation and flattening of the Wnt signalling gradient. Thus, Wnt and Src-YAP signals cooperate to drive intestinal regeneration.

NEDD4 and NEDD4L regulate Wnt signalling and intestinal stem cell priming by degrading LGR5 receptor.

The intestinal stem cell (ISC) marker LGR5 is a receptor for R-spondin (RSPO) that functions to potentiate Wnt signalling in the proliferating crypt. It has been recently shown that Wnt plays a priming role for ISC self-renewal by inducing RSPO receptor LGR5 expression. Despite its pivotal role in homeostasis, regeneration and cancer, little is known about the post-translational regulation of LGR5. Here, we show that the HECT-domain E3 ligases NEDD4 and NEDD4L are expressed in the crypt stem cell regions and regulate ISC priming by degrading LGR receptors. Loss of Nedd4 and Nedd4l enhances ISC proliferation, increases sensitivity to RSPO stimulation and accelerates tumour development in Apcmin mice with increased numbers of high-grade adenomas. Mechanistically, we find that both NEDD4 and NEDD4L negatively regulate Wnt/ß-catenin signalling by targeting LGR5 receptor and DVL2 for proteasomal and lysosomal degradation. Our findings unveil the previously unreported post-translational control of LGR receptors via NEDD4/NEDD4L to regulate ISC priming. Inactivation of NEDD4 and NEDD4L increases Wnt activation and ISC numbers, which subsequently enhances tumour predisposition and progression.

Hallmarks of intestinal stem cells.

Intestinal stem cells (ISCs) are highly proliferative cells that fuel the continuous renewal of the intestinal epithelium. Understanding their regulatory mechanisms during tissue homeostasis is key to delineating their roles in development and regeneration, as well as diseases such as bowel cancer and inflammatory bowel disease. Previous studies of ISCs focused mainly on the position of these cells along the intestinal crypt and their capacity for multipotency. However, evidence increasingly suggests that ISCs also exist in distinct cellular states, which can be an acquired rather than a hardwired intrinsic property. In this Review, we summarise the recent findings into how ISC identity can be defined by proliferation state, signalling crosstalk, epigenetics and metabolism, and propose an update on the hallmarks of ISCs. We further discuss how these properties contribute to intestinal development and the dynamics of injury-induced regeneration.

Cell-type-specific signaling networks in heterocellular organoids.

Despite the widespread adoption of organoids as biomimetic tissue models, methods to comprehensively analyze cell-type-specific post-translational modification (PTM) signaling networks in organoids are absent. Here, we report multivariate single-cell analysis of such networks in organoids and organoid cocultures. Simultaneous analysis by mass cytometry of 28 PTMs in >1 million single cells derived from small intestinal organoids reveals cell-type- and cell-state-specific signaling networks in stem, Paneth, enteroendocrine, tuft and goblet cells, as well as enterocytes. Integrating single-cell PTM analysis with thiol-reactive organoid barcoding in situ (TOBis) enables high-throughput comparison of signaling networks between organoid cultures. Cell-type-specific PTM analysis of colorectal cancer organoid cocultures reveals that shApc, KrasG12D and Trp53R172H cell-autonomously mimic signaling states normally induced by stromal fibroblasts and macrophages. These results demonstrate how standard mass cytometry workflows can be modified to perform high-throughput multivariate cell-type-specific signaling analysis of healthy and cancerous organoids.

Characterization of thylakoid division using chloroplast dividing mutants in Arabidopsis.

Chloroplasts are double membrane bound organelles that are found in plants and algae. Their division requires a number of proteins to assemble into rings along the center of the organelle and to constrict in synchrony. Chloroplasts possess a third membrane system, the thylakoids, which house the majority of proteins responsible for the light-dependent reactions. The mechanism that allows chloroplasts to sort out and separate the intricate thylakoid membrane structures during organelle division remain unknown. By characterizing the sizes of thylakoids found in a number of different chloroplast division mutants in Arabidopsis, we show that thylakoids do not divide independently of the chloroplast division cycle. More specifically, we show that thylakoid division requires the formation of both the inner and the outer contractile rings of the chloroplast.

Arabidopsis calmodulin-like proteins CML13 and CML14 interact with proteins that have IQ domains.

In response to Ca2+ signals, the evolutionarily-conserved Ca2+ sensor calmodulin (CaM) regulates protein targets via direct interaction. Plants possess many CaM-like (CML) proteins, but their binding partners and functions are mostly unknown. Here, using Arabidopsis CML13 as 'bait' in a yeast two-hybrid screen, we isolated putative targets from three, unrelated protein families, namely, IQD proteins, calmodulin-binding transcriptional activators (CAMTAs) and myosins, all of which possess tandem isoleucine-glutamine (IQ) structural domains. Using the split-luciferase complementation assay in planta and the yeast 2-hybrid system, CML13 and CML14 showed a preference for interaction with tandem over single IQ domains. Relative to CaM, CML13 and CML14 displayed weaker signals when tested with the non-IQ, CaM-binding domain of glutamate decarboxylase or the single IQ domains of CNGC20 (cyclic-nucleotide gated channel-20) or IQM1 (IQ motif protein1). We examined IQD14 as a representative tandem IQ-protein and found that only CaM, CML13 and CML14 interacted with IQD14 among 12 CaM/CMLs tested. CaM, CML13 and CML14 bound in vitro to IQD14 in the presence or absence of Ca2+ . Binding affinities were in the nM range and were higher when two tandem IQ domains from IQD14 were present. Green fluorescent protein-tagged versions of CaM, CML13 and CML14 localized to both the cytosol and nucleus in plant cells but were partially relocalized to the microtubules when co-expressed with IQD14 tagged with mCherry. These and other data are discussed in the context of possible roles for these CMLs in gene regulation via CAMTAs and cytoskeletal activity via myosins and IQD proteins.

Acute promyelocytic leukaemia: population-based study of epidemiology and outcome with ATRA and oral-ATO from 1991 to 2021.

BACKGROUND: The epidemiology and treatment of acute promyelocytic leukaemia (APL) are changing. We have incorporated oral arsenic trioxide (oral-ATO) into induction/maintenance. METHODS: Newly-diagnosed APL from 1991 to 2021 divided into three 10-year periods were studied to define its epidemiology and how oral-ATO impacted on its outcome. Primary endpoints included APL incidence, early deaths (ED, first 30 days), and overall survival (OS). Secondary endpoints included post-30-day OS, relapse-free survival (RFS), and incidence of second cancers. RESULTS: APL occurred in 374 males and 387 females at a median age of 44 (1-97) years. Annual incidences increased progressively, averaging 0.32 per 100,000 people. All-trans retinoic acid (ATRA)-based and oral-ATO-based regimens were used in 469 and 282 patients. There were 144 EDs, occurring almost exclusively in ATRA-based inductions (N = 139), being more with males, age > 50 years, leucocyte > 10 × 109/L, diagnosis during 1991-2009 and fewer with oral-ATO-based regimens. After a median of 75 (interquartile range: 14-161) months, 5-year and 10-year OS were 68.1% and 63.3%, inferior with males, age > 50 years, leucocyte > 10 × 109/L, high-risk Sanz score and superior with oral-ATO-based regimens. Factoring out EDs, 5-year and 10-year post-30-day OS were 84.0% and 78.1%, inferior with males and superior with oral-ATO-based regimens. In 607 CR1 patients, the 5-year RFS was 83.8%, superior with diagnosis in 2010-2021 and oral-ATO-based regimens. Second cancers developed in 21 patients, unrelated to oral-ATO-based regimens. CONCLUSIONS: There was an increasing incidence of APL, and all survivals were superior with the use of oral-ATO-based regimens. This study formed part of the Acute Promyelocytic Leukaemia Asian Consortium Project (ClinicalTrials.gov identifier: NCT04251754).

Allogeneic haematopoietic stem cell transplantation for myelofibrosis: prognostic indicators and the role of JAK2V617F measurable-residual disease monitoring by droplet-digital polymerase chain reaction.

Relapse after allogeneic haematopoietic stem cell transplantation (HSCT) is one of the key determinants of outcome in myelofibrosis (MF) and remains an important unmet need. In this retrospective single-centre study, we evaluated 35 consecutive patients with MF receiving allogeneic HSCT. At 30 days post-HSCT, full donor chimerism was achieved in 31 patients (88.6%). The median time to neutrophil engraftment was 16.8 (10-42) days and the median time to platelet engraftment was 26 (12-245) days. Four patients (11.4%) experienced primary graft failure. With a median duration of follow-up of 33 (1-223) months, with the 5-year overall survival (OS) and progression-free survival (PFS) were 51.6% and 46.3%, respectively. Relapse after HSCT (P < 0.001), leucocyte count ≥ 18 × 109/L at HSCT (P = 0.003) and accelerated/blast phase disease at HSCT (P < 0.001) were significantly associated with worse OS. Age at HSCT ≥ 54 years (P = 0.01), mutated ETV6 (P = 0.03), leucocyte count ≥ 18 × 109/L (P = 0.02), accelerated/blast phase MF (P = 0.001), and grade 2-3 bone marrow reticulin fibrosis at 12 months post-HSCT (P = 0.002) were significantly associated with worse PFS. JAK2V617F MRD ≥ 0.047 [sensitivity 85.7%; positive predictive value (PPV) 100%; AUC 0.984; P = 0.001] at 6 months and JAK2V617F MRD ≥ 0.009 (sensitivity 100%; PPV 100%; AUC 1.0; P = 0.001) at 12 months were highly predictive of post-HSCT relapse. Inferior OS and PFS were significantly associated with detectable JAK2V617F MRD at 12 months (P = 0.003 and P = 0.0001, respectively).

Metabolic precision labeling enables selective probing of O-linked N-acetylgalactosamine glycosylation.

Protein glycosylation events that happen early in the secretory pathway are often dysregulated during tumorigenesis. These events can be probed, in principle, by monosaccharides with bioorthogonal tags that would ideally be specific for distinct glycan subtypes. However, metabolic interconversion into other monosaccharides drastically reduces such specificity in the living cell. Here, we use a structure-based design process to develop the monosaccharide probe N-(S)-azidopropionylgalactosamine (GalNAzMe) that is specific for cancer-relevant Ser/Thr(O)-linked N-acetylgalactosamine (GalNAc) glycosylation. By virtue of a branched N-acylamide side chain, GalNAzMe is not interconverted by epimerization to the corresponding N-acetylglucosamine analog by the epimerase N-acetylgalactosamine-4-epimerase (GALE) like conventional GalNAc-based probes. GalNAzMe enters O-GalNAc glycosylation but does not enter other major cell surface glycan types including Asn(N)-linked glycans. We transfect cells with the engineered pyrophosphorylase mut-AGX1 to biosynthesize the nucleotide-sugar donor uridine diphosphate (UDP)-GalNAzMe from a sugar-1-phosphate precursor. Tagged with a bioorthogonal azide group, GalNAzMe serves as an O-glycan-specific reporter in superresolution microscopy, chemical glycoproteomics, a genome-wide CRISPR-knockout (CRISPR-KO) screen, and imaging of intestinal organoids. Additional ectopic expression of an engineered glycosyltransferase, "bump-and-hole" (BH)-GalNAc-T2, boosts labeling in a programmable fashion by increasing incorporation of GalNAzMe into the cell surface glycoproteome. Alleviating the need for GALE-KO cells in metabolic labeling experiments, GalNAzMe is a precision tool that allows a detailed view into the biology of a major type of cancer-relevant protein glycosylation.

Assessment of the Short Grit Scale in patients with substance use disorder: Psychometric properties and patient characteristics.

Background: Recovery from substance use disorder requires sustained effort and perseverance. Hence, the resilience factor of grit may be important for people in recovery. Little research has been conducted on grit in patients with substance use disorder (SUD), especially in a large and varied sample.Objectives: To analyze the psychometric properties of the Short Grit Scale (Grit-S) in patients with SUD and to use demographic and clinical characteristics to predict variance in Grit-S scores.Methods: Participants completed the Grit-S and other self-report measures. Psychometric properties of the Grit-S were assessed in outpatients (N = 94, 77.7% male) and a hierarchical regression predicted Grit-S variance in inpatients (N = 1238, 65.0% male).Results: The Grit-S demonstrated good internal consistency (α=.75) and strong test-retest reliability (adjusted r = .79, p < .001). Mean Grit-S score was 3.15, lower than other clinical samples reported in the literature. Regression modeling indicated a moderate, statistically significant association between demographic and clinical characteristics and Grit-S scores (R2 = 15.5%, p < .001). Of particular interest, the positive factor of recovery protection showed the strongest association with Grit-S of all variables assessed (ß=.185 vs. ß = .052-.175 for the remaining significant independent variables).Conclusion: The psychometric properties of the Grit-S in patients with SUD support its use in this population. Moreover, the particularly low grit scores among inpatients with SUDs and the association of grit scores with substance use risk and recovery factors suggest that grit could be useful as a treatment target in this population.

Prognostic factors of overall survival in patients with recurrent disease following liver resection for colorectal cancer metastases: A multicenter external validation study.

BACKGROUND: The clinical course of patients experiencing recurrence following hepatectomy for colorectal cancer metastases (CRM) is poorly defined. Previous studies associated shorter time to recurrence (TTR) in months, node-positive primary tumor, and more than one site of recurrence with worse outcomes. METHODS: We conducted a retrospective cohort study across four Canadian institutions to externally validate previously established prognostic factors of overall survival (OS). We included consecutive adult patients who had a recurrence following curative-intent liver resection for CRM. Prognostic factors were explored using a multivariable Cox regression model. Risk group cutoffs were identified through recursive partitioning. OS between low- and high-risk groups was compared using the Kaplan-Meier method. RESULTS: This study included 471 patients. Shorter TTR in months (hazard ratio [HR]: 0.95, 95% confidence interval [CI]: 0.93-0.97), presence of extrahepatic disease at first hepatectomy (HR: 2.54, 95% CI: 1.18-5.50), and larger tumor size in millimetres (HR: 1.01, 95% CI: 1.00-1.02) were associated with worse OS. Median OS in the high- and low-risk groups were 40.5 (95% CI: 34.0-45.7 months) versus 64.7 months (95% CI: 57.9-72.3 months; p < 0.001), respectively. CONCLUSIONS: We externally validated the prognostic significance of shorter TTR (<8.5 months) as a predictor of worse OS in patients who recur the following hepatectomy for CRM.

Systolic and diastolic functional reserve of the subpulmonary and systemic right ventricles as assessed by pharmacologic and exercise stress: A systematic review.

We performed a systematic review of the literature on the assessment of subpulmonary and systemic right ventricular (RV) functional reserve during pharmacological and exercise stress in congenital heart patients and patients with pulmonary arterial hypertension (PAH). Literature search was conducted using PubMed, EMBASE, and MEDLINE from their inception up to August 2020. Of 913 records identified, 56 studies with a total of 1730 patients were included. Of the 56 studies, 23 assessed subpulmonary RV functional reserve in repaired tetralogy of Fallot patients, 19 assessed systemic RV reserve in patients with transposition of the great arteries (TGA) after atrial switch and those with congenitally corrected TGA, and 14 assessed subpulmonary RV research in patients with PAH. Pharmacological and exercise stress was used, respectively, in 22 and 34 studies. The main findings were (1) impairment of RV systolic and diastolic functional reserve, (2) associations between impaired functional reserve and worse baseline functional parameters, and (3) prognostic implications of RV systolic functional reserve on clinical outcomes in patients with volume and/or pressure-loaded subpulmonary and systemic right ventricles. Further studies are required to establish the incremental value of incorporating stress studies of RV systolic and diastolic function in the clinical management algorithm of congenital heart patients and patients with PAH.

Frailty Predicts Postoperative Complications following Pancreaticoduodenectomy.

INTRODUCTION: Frailty is a clinically recognizable state of decreased reserve and function across physiologic systems, characterized by an inability to cope with acute stressors. A validated modified frailty index (mFI) was used to evaluate the impact of frailty on postoperative complications following pancreaticoduodenectomy. METHODS: Data from consecutive patients undergoing pancreaticoduodenectomy from 2011 to 2020 were collected retrospectively at a high-volume tertiary care hepatopancreatobiliary hospital. Based on an 11-item mFI, patients were grouped by high (≥0.27) and low mFI. The main outcome was postoperative complications (Clavien-Dindo classification). The impact of frailty on complications was analyzed by evaluating baseline and operative characteristics using multivariable logistic regression. Secondary outcomes included postoperative mortality, length of hospital stay, and intensive care unit (ICU) admission, which were analyzed using univariable logistic regression. RESULTS: There were 64/554 patients (12%) with high mFI. Low and high mFI had similar characteristics, including proportion of pancreatic adenocarcinoma (low mFI = 247/490 [50%] vs. high mFI = 31/64 [48%], p = 0.767), intermediate or hard pancreatic texture (low mFI = 75/191 [39%] vs. high mFI = 6/19 [32%], p = 0.512), operative room time (low mFI = 370 min vs. high mFI = 368 min, p = 0.630), and drain placement (low mFI = 355/490 [72%] vs. high mFI = 48/64 [75%], p = 0.642). The mFI score was an independent predictor for the development of any type of postoperative complications (OR 1.44, 95% CI 1.02-2.10) and major postoperative complications (OR 1.44, 95% CI 1.05-1.98) by multivariable analysis. High mFI patients had a higher 90-day mortality rate (high mFI = 7/64 [11%] vs. low mFI = 20/490 [4.1%], p = 0.017), a longer median length of hospital stay (high mFI = 11 days vs. low mFI = 8 days, p = 0.016), and a higher rate of ICU admission (high mFI = 47/64 [73%] vs. low mFI = 211/490 [43%], p < 0.001). CONCLUSION: Among patients who are considered surgical candidates, the mFI can identify those at high risk of developing postoperative complications. This tool can be used to accurately discuss postoperative risk with patients undergoing pancreaticoduodenectomy.

Right Ventricular-Pulmonary Arterial Coupling in Repaired Tetralogy of Fallot.

We assessed right ventricular (RV)-pulmonary arterial (PA) coupling in patients with repaired tetralogy of Fallot (TOF). Sixty patients (34 males) aged 18.6 ± 8.3 years at 14.8 ± 7.4 years after repair and 60 controls were studied. Two-dimensional, tissue Doppler and speckle tracking echocardiography and colour flow mapping were performed to assess RV end-systolic (ESA) and -diastolic areas, tricuspid valve Doppler and myocardial velocities, left ventricular (LV) and RV deformation and pulmonary (PR), tricuspid regurgitation (TR), respectively. The ratios of RV area change to ESA and peak tricuspid annular systolic (s) velocity to RV ESA indexed to body surface area reflected RV-PA coupling. Patients had greater RV areas and reduced tricuspid annular and myocardial velocities, LV and RV myocardial mechanics compared to controls (all p < 0.05). Both RV area change/ESA ratio and peak tricuspid annular s velocity/indexed RV ESA ratio were reduced in patients (all p < 0.001). Sixty-one and 100% of patients had, respectively, RV area change/ESA ratio and peak tricuspid annular s velocity/indexed RV ESA ratio < -2SD of controls. Indices of RV-PA coupling correlated positively with tricuspid myocardial velocities, LV and RV deformation and inversely with PR and TR (all p < 0.05). Multivariate analysis showed RV systolic strain rate, PR and TR as independent predictors of both RV-PA coupling indices, whilst age, gender and LV systolic strain were also predictors of peak tricuspid annular s velocity/indexed RV ESA ratio (all p < 0.05). In conclusion, RV-PA coupling is impaired and is associated with RV and LV mechanics and severity of PR and TR in patients with repaired TOF.