Attacking Latent HIV with convertibleCAR-T Cells, a Highly Adaptable Killing Platform.

Current approaches to reducing the latent HIV reservoir entail first reactivating virus-containing cells to become visible to the immune system. A critical second step is killing these cells to reduce reservoir size. Endogenous cytotoxic T-lymphocytes (CTLs) may not be adequate because of cellular exhaustion and the evolution of CTL-resistant viruses. We have designed a universal CAR-T cell platform based on CTLs engineered to bind a variety of broadly neutralizing anti-HIV antibodies. We show that this platform, convertibleCAR-T cells, effectively kills HIV-infected, but not uninfected, CD4 T cells from blood, tonsil, or spleen and only when armed with anti-HIV antibodies. convertibleCAR-T cells also kill within 48 h more than half of the inducible reservoir found in blood of HIV-infected individuals on antiretroviral therapy. The modularity of convertibleCAR-T cell system, which allows multiplexing with several anti-HIV antibodies yielding greater breadth and control, makes it a promising tool for attacking the latent HIV reservoir.

A proliferative burst during preadolescence establishes the final cardiomyocyte number.

It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases.

RNA Pol II-dependent transcription efficiency fine-tunes A-to-I editing levels.

A-to-I RNA editing is a widespread epitranscriptomic phenomenon leading to the conversion of adenosines to inosines, which are primarily interpreted as guanosines by cellular machines. Consequently, A-to-I editing can alter splicing or lead to recoding of transcripts. As misregulation of editing can cause a variety of human diseases, A-to-I editing requires tight regulation of the extent of deamination, particularly in protein-coding regions. The bulk of A-to-I editing occurs cotranscriptionally. Thus, we studied A-to-I editing regulation in the context of transcription and pre-mRNA processing. We show that stimulation of transcription impacts editing levels. Activation of the transcription factor MYC leads to an up-regulation of A-to-I editing, particularly in transcripts that are suppressed upon MYC activation. Moreover, low pre-mRNA synthesis rates and low pre-mRNA expression levels support high levels of editing. We also show that editing levels greatly differ between nascent pre-mRNA and mRNA in a cellular system, as well as in mouse tissues. Editing levels can increase or decrease from pre-mRNA to mRNA and can vary across editing targets and across tissues, showing that pre-mRNA processing is an important layer of editing regulation. Several lines of evidence suggest that the differences emerge during pre-mRNA splicing. Moreover, actinomycin D treatment of primary neuronal cells and editing level analysis suggests that regulation of editing levels also depends on transcription.

Tyrosine-1 of RNA Polymerase II CTD Controls Global Termination of Gene Transcription in Mammals.

The carboxy-terminal domain (CTD) of RNA polymerase (Pol) II is composed of a repetition of YSPTSPS heptads and functions as a loading platform for protein complexes that regulate transcription, splicing, and maturation of RNAs. Here, we studied mammalian CTD mutants to analyze the function of tyrosine1 residues in the transcription cycle. Mutation of 3/4 of the tyrosine residues (YFFF mutant) resulted in a massive read-through transcription phenotype in the antisense direction of promoters as well as in the 3' direction several hundred kilobases downstream of genes. The YFFF mutant shows reduced Pol II at promoter-proximal pause sites, a loss of interaction with the Mediator and Integrator complexes, and impaired recruitment of these complexes to chromatin. Consistent with these observations, Pol II loading at enhancers and maturation of snRNAs are altered in the YFFF context genome-wide. We conclude that tyrosine1 residues of the CTD control termination of transcription by Pol II.

TGFß/activin-dependent activation of Torso controls the timing of the metamorphic transition in the red flour beetle Tribolium castaneum.

Understanding the mechanisms governing body size attainment during animal development is of paramount importance in biology. In insects, a crucial phase in determining body size occurs at the larva-pupa transition, marking the end of the larval growth period. Central to this process is the attainment of the threshold size (TS), a critical developmental checkpoint that must be reached before the larva can undergo metamorphosis. However, the intricate molecular mechanisms by which the TS orchestrates this transition remain poor understood. In this study, we investigate the role of the interaction between the Torso and TGFß/activin signaling pathways in regulating metamorphic timing in the red flour beetle, Tribolium castaneum. Our results show that Torso signaling is required specifically during the last larval instar and that its activation is mediated not only by the prothoracicotropic hormone (Tc-Ptth) but also by Trunk (Tc-Trk), another ligand of the Tc-Torso receptor. Interestingly, we show that while Tc-Torso activation by Tc-Ptth determines the onset of metamorphosis, Tc-Trk promotes growth during the last larval stage. In addition, we found that the expression of Tc-torso correlates with the attainment of the TS and the decay of juvenile hormone (JH) levels, at the onset of the last larval instar. Notably, our data reveal that activation of TGFß/activin signaling pathway at the TS is responsible for repressing the JH synthesis and inducing Tc-torso expression, initiating metamorphosis. Altogether, these findings shed light on the pivotal involvement of the Ptth/Trunk/Torso and TGFß/activin signaling pathways as critical regulatory components orchestrating the TS-driven metamorphic initiation, offering valuable insights into the mechanisms underlying body size determination in insects.

Reward-Mediated, Model-Free Reinforcement-Learning Mechanisms in Pavlovian and Instrumental Tasks Are Related.

Model-free and model-based computations are argued to distinctly update action values that guide decision-making processes. It is not known, however, if these model-free and model-based reinforcement learning mechanisms recruited in operationally based instrumental tasks parallel those engaged by pavlovian-based behavioral procedures. Recently, computational work has suggested that individual differences in the attribution of incentive salience to reward predictive cues, that is, sign- and goal-tracking behaviors, are also governed by variations in model-free and model-based value representations that guide behavior. Moreover, it is not appreciated if these systems that are characterized computationally using model-free and model-based algorithms are conserved across tasks for individual animals. In the current study, we used a within-subject design to assess sign-tracking and goal-tracking behaviors using a pavlovian conditioned approach task and then characterized behavior using an instrumental multistage decision-making (MSDM) task in male rats. We hypothesized that both pavlovian and instrumental learning processes may be driven by common reinforcement-learning mechanisms. Our data confirm that sign-tracking behavior was associated with greater reward-mediated, model-free reinforcement learning and that it was also linked to model-free reinforcement learning in the MSDM task. Computational analyses revealed that pavlovian model-free updating was correlated with model-free reinforcement learning in the MSDM task. These data provide key insights into the computational mechanisms mediating associative learning that could have important implications for normal and abnormal states.SIGNIFICANCE STATEMENT Model-free and model-based computations that guide instrumental decision-making processes may also be recruited in pavlovian-based behavioral procedures. Here, we used a within-subject design to test the hypothesis that both pavlovian and instrumental learning processes were driven by common reinforcement-learning mechanisms. Sign-tracking and goal-tracking behaviors were assessed in rats using a pavlovian conditioned approach task, and then instrumental behavior was characterized using an MSDM task. We report that sign-tracking behavior was associated with greater model-free, but not model-based, learning in the MSDM task. These data suggest that pavlovian and instrumental behaviors may be driven by conserved reinforcement-learning mechanisms.

Decreased Ventral Tegmental Area CB1R Signaling Reduces Sign Tracking and Shifts Cue-Outcome Dynamics in Rat Nucleus Accumbens.

Sign-tracking (ST) rats show enhanced cue sensitivity before drug experience that predicts greater discrete cue-induced drug seeking compared with goal-tracking or intermediate rats. Cue-evoked dopamine in the nucleus accumbens (NAc) is a neurobiological signature of sign-tracking behaviors. Here, we examine a critical regulator of the dopamine system, endocannabinoids, which bind the cannabinoid receptor-1 (CB1R) in the ventral tegmental area (VTA) to control cue-evoked striatal dopamine levels. We use cell type-specific optogenetics, intra-VTA pharmacology, and fiber photometry to test the hypothesis that VTA CB1R receptor signaling regulates NAc dopamine levels to control sign tracking. We trained male and female rats in a Pavlovian lever autoshaping (PLA) task to determine their tracking groups before testing the effect of VTA → NAc dopamine inhibition. We found that this circuit is critical for mediating the vigor of the ST response. Upstream of this circuit, intra-VTA infusions of rimonabant, a CB1R inverse agonist, during PLA decrease lever and increase food cup approach in sign-trackers. Using fiber photometry to measure fluorescent signals from a dopamine sensor, GRABDA (AAV9-hSyn-DA2m), we tested the effects of intra-VTA rimonabant on NAc dopamine dynamics during autoshaping in female rats. We found that intra-VTA rimonabant decreased sign-tracking behaviors, which was associated with increases in NAc shell, but not core, dopamine levels during reward delivery [unconditioned stimulus (US)]. Our results suggest that CB1R signaling in the VTA influences the balance between the conditioned stimulus-evoked and US-evoked dopamine responses in the NAc shell and biases behavioral responding to cues in sign-tracking rats.SIGNIFICANCE STATEMENT Substance use disorder (SUD) is a chronically relapsing psychological disorder that affects a subset of individuals who engage in drug use. Recent research suggests that there are individual behavioral and neurobiological differences before drug experience that predict SUD and relapse vulnerabilities. Here, we investigate how midbrain endocannabinoids regulate a brain pathway that is exclusively involved in driving cue-motivated behaviors of sign-tracking rats. This work contributes to our mechanistic understanding of individual vulnerabilities to cue-triggered natural reward seeking that have relevance for drug-motivated behaviors.

CLUH granules coordinate translation of mitochondrial proteins with mTORC1 signaling and mitophagy.

Mitochondria house anabolic and catabolic processes that must be balanced and adjusted to meet cellular demands. The RNA-binding protein CLUH (clustered mitochondria homolog) binds mRNAs of nuclear-encoded mitochondrial proteins and is highly expressed in the liver, where it regulates metabolic plasticity. Here, we show that in primary hepatocytes, CLUH coalesces in specific ribonucleoprotein particles that define the translational fate of target mRNAs, such as Pcx, Hadha, and Hmgcs2, to match nutrient availability. Moreover, CLUH granules play signaling roles, by recruiting mTOR kinase and the RNA-binding proteins G3BP1 and G3BP2. Upon starvation, CLUH regulates translation of Hmgcs2, involved in ketogenesis, inhibits mTORC1 activation and mitochondrial anabolic pathways, and promotes mitochondrial turnover, thus allowing efficient reprograming of metabolic function. In the absence of CLUH, a mitophagy block causes mitochondrial clustering that is rescued by rapamycin treatment or depletion of G3BP1 and G3BP2. Our data demonstrate that metabolic adaptation of liver mitochondria to nutrient availability depends on a compartmentalized CLUH-dependent post-transcriptional mechanism that controls both mTORC1 and G3BP signaling and ensures survival.

Comparison of outcomes and required tools between transvenous extraction of pacemaker and implantable cardioverter defibrillator leads: Insight from single high-volume center experience.

INTRODUCTION: Reports of comparison with procedural outcomes for implantable cardioverter defibrillator (ICD) and pacemaker (PM) transvenous lead extraction (TLE) are old and limited. We sought to compare the safety, efficacy, and procedural properties of ICD and PM TLE and assess the impact of lead age. METHODS: The study cohort included all consecutive patients with ICD and PM TLE in the Cleveland Clinic Prospective TLE Registry between 2013 and 2022. Extraction success, complications, and failure employed the definitions described in the HRS 2017 TLE guidelines. RESULTS: A total of 885 ICD leads, a median implant duration of 8 (5-11) years in 810 patients, and 1352 PM leads of 7 (3-13) years in 807 patients were included. Procedural success rates in ICD patients were superior to those of PM in >20 years leads but similar in ≤20 years leads. In the PM group, the complete success rate of TLE decreased significantly according to the increase of lead age, but not in the ICD group. ICD TLE required more extraction tools compared with PM TLE but cases with older leads required non-laser sheath extraction tools in both groups. The most common injury site in major complication cases differed between ICD and PM TLE, although major complication rates showed no difference in both groups (2.7% vs. 1.6%, p = .12). CONCLUSION: The procedural success rate by TLE is greater for ICD patients than PM patients with leads >20 years old but requires more extraction tools. Common vascular complication sites and the impact of lead age on procedural outcomes and required tools differed between ICD and PM TLE.

Persistence of significant secondary mitral regurgitation post-cardiac resynchronization therapy and survival: a systematic review and meta-analysis : Mitral regurgitation and mortality post-CRT.

Cardiac resynchronization therapy (CRT) significantly reduces secondary mitral regurgitation (MR) in patients with severe left ventricular systolic dysfunction. However, uncertainty remains as to whether improvement in secondary MR correlates with improvement with mortality seen in CRT. We conducted a meta-analysis to determine the association of persistent unimproved significant secondary MR (defined as moderate or moderate-to-severe or severe MR) compared to improved MR (no MR or mild MR) post-CRT with all-cause mortality, cardiovascular mortality, and heart failure hospitalization. A systematic search of PubMed, EMBASE, and Cochrane Library databases till July 31, 2022 identified studies reporting clinical outcomes by post-CRT secondary MR status. In 12 prospective studies of 4954 patients (weighted mean age 66.8 years, men 77.8%), the median duration of follow-up post-CRT at which patients were re-evaluated for significant secondary MR was 6 months and showed significant relative risk reduction of 30% compared to pre-CRT. The median duration of follow-up post-CRT for ascertainment of main clinical outcomes was 38 months. The random effects pooled hazard ratio (95% confidence interval) of all-cause mortality in patients with unimproved secondary MR compared to improved secondary MR was 2.00 (1.57-2.55); p < 0.001). There was insufficient data to evaluate secondary outcomes in a meta-analysis, but limited data that examined the relationship showed significant association of unimproved secondary MR with increased cardiovascular mortality and heart failure hospitalization. The findings of this meta-analysis suggest that lack of improvement in secondary MR post-CRT is associated with significantly elevated risk of all-cause mortality and possibly cardiovascular mortality and heart failure hospitalization. Future studies may investigate approaches to address persistent secondary MR post-CRT to help improved outcome in this population.

Intraoperative physician assessment during total hip arthroplasty correlates with DXA parameters.

PURPOSE: Orthopedic surgeons can assess bone status intraoperatively and recommend skeletal health evaluation for patients with poor bone quality. Intraoperative physician assessment (IPA) at the time of total knee arthroplasty correlates with preoperative DXA-measured bone mineral density (BMD). This study evaluated IPA during total hip arthroplasty (THA) as a quantitative measure of bone status based on tactile assessment. METHODS: This retrospective analysis identified 60 patients (64 hips) undergoing primary THA who had IPA recorded in the operative report and a DXA within 2 years before surgery. Intraoperatively, two surgeons assessed bone quality on a 5-point scale (1 = excellent; 5 = poor). IPA score was compared to DXA BMD and T-score, 3D Shaper measurements, WHO classification, FRAX scores, radiographic Dorr classification, and cortical index. RESULTS: There was a strong correlation between the IPA score and lowest T-score, WHO classification, and FRAX major and hip fracture scores (r = ± 0.485-0.622, all p < 0.001). There was a moderate correlation between IPA score and total hip BMD and 3D Shaper measurements, including trabecular volumetric BMD, cortical surface BMD, and cortical thickness (r = ± 0.326-0.386, all p < 0.01). All patients with below-average IPA scores had osteopenia or osteoporosis by DXA. CONCLUSION: IPA during THA is a simple, valuable tool for quantifying bone status based on tactile feedback. This information can be used to identify patients with poor bone quality that may benefit from skeletal status evaluation and treatment and provide intraoperative guidance for implant selection. Orthopedic surgeons can assess bone health at the time of surgery. Intraoperative physician assessment (IPA) is a bone quality score based on surgeons' tactile assessment that correlates strongly with the lowest T-score, WHO classification, and FRAX fracture risk. IPA can guide surgical decision-making and future bone health treatment.

Tet enzymes are essential for early embryogenesis and completion of embryonic genome activation.

Mammalian development begins in transcriptional silence followed by a period of widespread activation of thousands of genes. DNA methylation reprogramming is integral to embryogenesis and linked to Tet enzymes, but their function in early development is not well understood. Here, we generate combined deficiencies of all three Tet enzymes in mouse oocytes using a morpholino-guided knockdown approach and study the impact of acute Tet enzyme deficiencies on preimplantation development. Tet1-3 deficient embryos arrest at the 2-cell stage with the most severe phenotype linked to Tet2. Individual Tet enzymes display non-redundant roles in the consecutive oxidation of 5-methylcytosine to 5-carboxylcytosine. Gene expression analysis uncovers that Tet enzymes are required for completion of embryonic genome activation (EGA) and fine-tuned expression of transposable elements and chimeric transcripts. Whole-genome bisulfite sequencing reveals minor changes of global DNA methylation in Tet-deficient 2-cell embryos, suggesting an important role of non-catalytic functions of Tet enzymes in early embryogenesis. Our results demonstrate that Tet enzymes are key components of the clock that regulates the timing and extent of EGA in mammalian embryos.

Evolution and prognosis of tricuspid and mitral regurgitation following cardiac implantable electronic devices: a systematic review and meta-analysis.

AIMS: Significant changes in tricuspid regurgitation (TR) and mitral regurgitation (MR) post-cardiac implantable electronic devices (CIEDs) are increasingly recognized. However, uncertainty remains as to whether the risk of CIED-associated TR and MR differs with right ventricular pacing (RVP) via CIED with trans-tricuspid RV leads, compared with cardiac resynchronization therapy (CRT), conduction system pacing (CSP), and leadless pacing (LP). The study aims to synthesize extant data on risk and prognosis of significant post-CIED TR and MR across pacing strategies. METHODS AND RESULTS: We searched PubMed, EMBASE, and Cochrane Library databases published until 31 October 2023. Significant post-CIED TR and MR were defined as ≥ moderate. Fifty-seven TR studies (n = 13 723 patients) and 90 MR studies (n = 14 387 patients) were included. For all CIED, the risk of post-CIED TR increased [pooled odds ratio (OR) = 2.46 and 95% CI = 1.88-3.22], while the risk of post-CIED MR reduced (OR = 0.74, 95% CI = 0.58-0.94) after 12 and 6 months of median follow-up, respectively. Right ventricular pacing via CIED with trans-tricuspid RV leads was associated with increased risk of post-CIED TR (OR = 4.54, 95% CI = 3.14-6.57) and post-CIED MR (OR = 2.24, 95% CI = 1.18-4.26). Binarily, CSP did not alter TR risk (OR = 0.37, 95% CI = 0.13-1.02), but significantly reduced MR (OR = 0.15, 95% CI = 0.03-0.62). Cardiac resynchronization therapy did not significantly change TR risk (OR = 1.09, 95% CI = 0.55-2.17), but significantly reduced MR with prevalence pre-CRT of 43%, decreasing post-CRT to 22% (OR = 0.49, 95% CI = 0.40-0.61). There was no significant association of LP with post-CIED TR (OR = 1.15, 95% CI = 0.83-1.59) or MR (OR = 1.31, 95% CI = 0.72-2.39). Cardiac implantable electronic device-associated TR was independently predictive of all-cause mortality [pooled hazard ratio (HR) = 1.64, 95% CI = 1.40-1.90] after median of 53 months. Mitral regurgitation persisting post-CRT independently predicted all-cause mortality (HR = 2.00, 95% CI = 1.57-2.55) after 38 months. CONCLUSION: Our findings suggest that, when possible, adoption of pacing strategies that avoid isolated trans-tricuspid RV leads may be beneficial in preventing incident or deteriorating atrioventricular valvular regurgitation and might reduce mortality.

Acute post-procedural inducibility is a poor predictor of clinical outcomes in high-risk patients (PAINESD > 17) undergoing scar-related ventricular tachycardia ablation.

AIMS: Ventricular tachycardia (VT) non-inducibility in response to programmed ventricular stimulation (PVS) is a widely used procedural endpoint for VT ablation despite inconclusive evidence with respect to clinical outcomes in high-risk patients. The aim is to determine the utility of acute post-ablation VT inducibility as a predictor of VT recurrence, mortality, or mortality equivalent in high-risk patients. METHODS AND RESULTS: We conducted a retrospective analysis of high-risk patients (defined as PAINESD > 17) who underwent scar-related VT ablation at our institution between July 2010 and July 2022. Patients' response to PVS (post-procedure) was categorized into three groups: Group A, no clinical VT or VT with cycle length > 240 ms inducible; Group B, only non-clinical VT with cycle length > 240 ms induced; and Group C, all other outcomes (including cases where no PVS was performed). The combined primary endpoint included death, durable left ventricular assist device placement, and cardiac transplant (Cox analysis). Ventricular tachycardia recurrence was considered a secondary endpoint (competing risk analysis). Of the 1677 VT ablation cases, 123 cases met the inclusion criteria for analysis. During a 19-month median follow-up time (interquartile range 4-43 months), 82 (66.7%) patients experienced the composite primary endpoint. There was no difference between Groups A and C with respect to the primary [hazard ratio (HR) = 1.21 (0.94-1.57), P = 0.145] or secondary [HR = 1.18 (0.91-1.54), P = 0.210] outcomes. These findings persisted after multivariate adjustments. The size of Group B (n = 13) did not permit meaningful statistical analysis. CONCLUSION: The results of post-ablation PVS do not significantly correlate with long-term outcomes in high-risk (PAINESD > 17) VT ablation patients.

Iron Chelation in Soil: Scalable Biotechnology for Accelerating Carbon Dioxide Removal by Enhanced Rock Weathering.

Enhanced rock weathering (EW) is an emerging atmospheric carbon dioxide removal (CDR) strategy being scaled up by the commercial sector. Here, we combine multiomics analyses of belowground microbiomes, laboratory-based dissolution studies, and incubation investigations of soils from field EW trials to build the case for manipulating iron chelators in soil to increase EW efficiency and lower costs. Microbial siderophores are high-affinity, highly selective iron (Fe) chelators that enhance the uptake of Fe from soil minerals into cells. Applying RNA-seq metatranscriptomics and shotgun metagenomics to soils and basalt grains from EW field trials revealed that microbial communities on basalt grains significantly upregulate siderophore biosynthesis gene expression relative to microbiomes of the surrounding soil. Separate in vitro laboratory incubation studies showed that micromolar solutions of siderophores and high-affinity synthetic chelator (ethylenediamine-N,N'-bis-2-hydroxyphenylacetic acid, EDDHA) accelerate EW to increase CDR rates. Building on these findings, we develop a potential biotechnology pathway for accelerating EW using the synthetic Fe-chelator EDDHA that is commonly used in agronomy to alleviate the Fe deficiency in high pH soils. Incubation of EW field trial soils with potassium-EDDHA solutions increased potential CDR rates by up to 2.5-fold by promoting the abiotic dissolution of basalt and upregulating microbial siderophore production to further accelerate weathering reactions. Moreover, EDDHA may alleviate potential Fe limitation of crops due to rising soil pH with EW over time. Initial cost-benefit analysis suggests potassium-EDDHA could lower EW-CDR costs by up to U.S. $77 t CO2 ha-1 to improve EW's competitiveness relative to other CDR strategies.

Superficial versus deep parasternal intercostal plane blocks: cadaveric evaluation of injectate spread.

BACKGROUND: Deep and superficial parasternal intercostal plane blocks provide anterior chest wall analgesia for both breast and cardiac surgery. Our primary objective of this cadaveric study was to describe the parasternal spread of deep and superficial parasternal intercostal plane blocks. Our secondary objectives were to describe needle proximity to the internal mammary artery when performing deep parasternal intercostal plane blocks, and compare lateral injectate spread and extension into the rectus sheath. METHODS: We performed ultrasound-guided deep and superficial parasternal intercostal plane blocks 2 cm from the sternum at the T3-4 interspace in four fresh frozen cadavers as described in clinical studies. RESULTS: Parasternal spread of injectate was greater with the deep parasternal intercostal plane injection than with the superficial parasternal intercostal plane injection. The internal mammary artery was ∼3 mm away from the needle trajectory in cadaver #1 and ∼5 mm from the internal mammary artery in cadaver #2. Lateral spread extended to the midclavicular line for all deep parasternal intercostal plane blocks and beyond the midclavicular line for all superficial parasternal intercostal plane blocks. Neither block extended to the rectus sheath. CONCLUSIONS: A greater number of parasternal interspaces were covered with the deep parasternal intercostal plane block than with the superficial parasternal intercostal plane block when one injection was performed at the T3-4 interspace. However, considering proximity to the internal mammary artery, and potential devastating consequences of an arterial injury, we propose that the deep parasternal intercostal plane block be classified as an advanced block and that future studies focus on optimising superficial parasternal intercostal plane parasternal spread.

Laparoscopic cholecystectomy critical view of safety (LC-CVS): a multi-national validation study of an objective, procedure-specific assessment using video-based assessment (VBA).

BACKGROUND: A novel 6-item objective, procedure-specific assessment for laparoscopic cholecystectomy incorporating the critical view of safety (LC-CVS OPSA) was developed to support trainee formative and summative assessments. The LC-CVS OPSA included two retraction items (fundus and infundibulum retraction) and four CVS items (hepatocystic triangle visualization, gallbladder-liver separation, cystic artery identification, and cystic duct identification). The scoring rubric for retraction consisted of poor (frequently outside of defined range), adequate (minimally outside of defined range) and excellent (consistently inside defined range) and for CVS items were "poor-unsafe", "adequate-safe", or "excellent-safe". METHODS: A multi-national consortium of 12 expert LC surgeons applied the OPSA-LC CVS to 35 unique LC videos and one duplicate video. Primary outcome measure was inter-rater reliability as measured by Gwet's AC2, a weighted measure that adjusts for scales with high probability of random agreement. Analysis of the inter-rater reliability was conducted on a collapsed dichotomous scoring rubric of "poor-unsafe" vs. "adequate/excellent-safe". RESULTS: Inter-rater reliability was high for all six items ranging from 0.76 (hepatocystic triangle visualization) to 0.86 (cystic duct identification). Intra-rater reliability for the single duplicate video was substantially higher across the six items ranging from 0.91 to 1.00. CONCLUSIONS: The novel 6-item OPSA LC CVS demonstrated high inter-rater reliability when tested with a multi-national consortium of LC expert surgeons. This brief instrument focused on safe surgical practice was designed to support the implementation of entrustable professional activities into busy surgical training programs. Instrument use coupled with video-based assessments creates novel datasets with the potential for artificial intelligence development including computer vision to drive assessment automation.

A multi-national, video-based qualitative study to refine training guidelines for assigning an "unsafe" score in laparoscopic cholecystectomy critical view of safety.

BACKGROUND: The critical view of safety (CVS) was incorporated into a novel 6-item objective procedure-specific assessment for laparoscopic cholecystectomy (LC-CVS OPSA) to enhance focus on safe completion of surgical tasks and advance the American Board of Surgery's entrustable professional activities (EPAs) initiative. To enhance instrument development, a feasibility study was performed to elucidate expert surgeon perspectives regarding "safe" vs. "unsafe" practice. METHODS: A multi-national consortium of 11 expert LC surgeons were asked to apply the LC-CVS OPSA to ten LC videos of varying surgical difficulty using a "safe" vs. "unsafe" scale. Raters were asked to provide written rationale for all "unsafe" ratings and invited to provide additional feedback regarding instrument clarity. A qualitative analysis was performed on written responses to extract major themes. RESULTS: Of the 660 ratings, 238 were scored as "unsafe" with substantial variation in distribution across tasks and raters. Analysis of the comments revealed three major categories of "unsafe" ratings: (a) inability to achieve the critical view of safety (intended outcome), (b) safe task completion but less than optimal surgical technique, and (c) safe task completion but risk for potential future complication. Analysis of reviewer comments also identified the potential for safe surgical practice even when CVS was not achieved, either due to unusual anatomy or severe pathology preventing safe visualization. Based upon findings, modifications to the instructions to raters for the LC-CVS OPSA were incorporated to enhance instrument reliability. CONCLUSIONS: A safety-based LC-CVS OPSA has the potential to significantly improve surgical training by incorporating CVS formally into learner assessment. This study documents the perspectives of expert biliary tract surgeons regarding clear identification and documentation of unsafe surgical practice for LC-CVS and enables the development of training materials to improve instrument reliability. Learnings from the study have been incorporated into rater instructions to enhance instrument reliability.