Ancestral genetic components are consistently associated with the complex trait landscape in European biobanks.

The genetic structure in Europe was mostly shaped by admixture between the Western Hunter-Gatherers, Early European Farmers and Steppe Bronze Age ancestral components. Such structure is regarded as a confounder in GWAS and follow-up studies, and gold-standard methods exist to correct for it. However, it is still poorly understood to which extent these ancestral components contribute to complex trait variation in present-day Europe. In this work we harness the UK Biobank to address this question. By extensive demographic simulations, exploiting data on siblings and incorporating previous results we obtained from the Estonian Biobank, we carefully evaluate the significance and scope of our findings. Heart rate, platelet count, bone mineral density and many other traits show stratification similar to height and pigmentation traits, likely targets of selection and divergence across ancestral groups. We show that the reported ancestry-trait associations are not driven by environmental confounders by confirming our results when using between-sibling differences in ancestry. The consistency of our results across biobanks further supports this and indicates that these genetic predispositions that derive from post-Neolithic admixture events act as a source of variability and as potential confounders in Europe as a whole.

Chronic osteoarthritis caused by Propionibacterium australiense infection in a captive sand gazelle.

Osteoarthritis is a common cause of morbidity and mortality in geriatric gazelles. Propionibacterium australiense has been reported as a cause of systemic granulomas in cattle, but there are no descriptions of this bacteria infecting other species nor causing osteoarthritis, to our knowledge. An 8-y-old, castrated male, sand gazelle (Gazella leptoceros leptoceros) was managed for chronic, intermittent, progressive osteoarthritis of the right tarsus. Serial biopsies revealed pyogranulomatous dermatitis with intralesional bacteria. Serial diagnostic imaging identified osseous and soft tissue proliferation with draining tracts. Treatments over 1 y included broad-spectrum antibiotics, anti-inflammatories, joint debridement, and infusion with platelet-rich plasma and stem cells. Despite therapy, lameness persisted, azotemia developed, and subsequently, the animal was euthanized. On postmortem examination, the periarticular tissue of the right tarsus was markedly expanded by pyogranulomas and fibrosis. Histologically, the synovium, joint capsule, and overlying soft tissues were markedly expanded by pyogranulomas and numerous gram-positive and acid-fast-negative filamentous bacteria surrounded by Splendore-Hoeppli material. Within the joint, there was regionally extensive cartilage ulceration, osteonecrosis, osteolysis, and pannus formation. PCR assay of affected formalin-fixed, paraffin-embedded tissue amplified segments of 16S rRNA and ß subunit of bacterial RNA polymerase (rpoB) genes with 99.7% and 95.6% identity to P. australiense. This bacterium should be considered a differential for chronic pyogranulomatous osteoarthritis in gazelles.

A phenome-wide association and factorial Mendelian randomization study on the repurposing of uric acid-lowering drugs for cardiovascular outcomes.

Uric acid has been linked to various disease outcomes. However, it remains unclear whether uric acid-lowering therapy could be repurposed as a treatment for conditions other than gout. We first performed both observational phenome-wide association study (Obs-PheWAS) and polygenic risk score PheWAS (PRS-PheWAS) to identify associations of uric acid levels with a wide range of disease outcomes. Then, trajectory analysis was conducted to explore temporal progression patterns of the observed disease outcomes. Finally, we investigated whether uric acid-lowering drugs could be repurposed using a factorial Mendelian randomization (MR) study design. A total of 41 overlapping phenotypes associated with uric acid levels were identified by both Obs- and PRS- PheWASs, primarily cardiometabolic diseases. The trajectory analysis illustrated how elevated uric acid levels contribute to cardiometabolic diseases, and finally death. Meanwhile, we found that uric acid-lowering drugs exerted a protective role in reducing the risk of coronary atherosclerosis (OR = 0.96, 95%CI: 0.93, 1.00, P = 0.049), congestive heart failure (OR = 0.64, 95%CI: 0.42, 0.99, P = 0.043), occlusion of cerebral arteries (OR = 0.93, 95%CI: 0.87, 1.00, P = 0.044) and peripheral vascular disease (OR = 0.60, 95%CI: 0.38, 0.94, P = 0.025). Furthermore, the combination of uric acid-lowering therapy (e.g. xanthine oxidase inhibitors) with antihypertensive treatment (e.g. calcium channel blockers) exerted additive effects and was associated with a 6%, 8%, 8%, 10% reduction in risk of coronary atherosclerosis, heart failure, occlusion of cerebral arteries and peripheral vascular disease, respectively. Our findings support a role of elevated uric acid levels in advancing cardiovascular dysfunction and identify potential repurposing opportunities for uric acid-lowering drugs in cardiovascular treatment.

Fast and facile synthesis of amidine-incorporated degradable lipids for versatile mRNA delivery in vivo.

Lipid nanoparticles (LNPs) are widely used for mRNA delivery, with cationic lipids greatly affecting biodistribution, cellular uptake, endosomal escape and transfection efficiency. However, the laborious synthesis of cationic lipids limits the discovery of efficacious candidates and slows down scale-up manufacturing. Here we develop a one-pot, tandem multi-component reaction based on the rationally designed amine-thiol-acrylate conjugation, which enables fast (1 h) and facile room-temperature synthesis of amidine-incorporated degradable (AID) lipids. Structure-activity relationship analysis of a combinatorial library of 100 chemically diverse AID-lipids leads to the identification of a tail-like amine-ring-alkyl aniline that generally affords efficacious lipids. Experimental and theoretical studies show that the embedded bulky benzene ring can enhance endosomal escape and mRNA delivery by enabling the lipid to adopt a more conical shape. The lead AID-lipid can not only mediate local delivery of mRNA vaccines and systemic delivery of mRNA therapeutics, but can also alter the tropism of liver-tropic LNPs to selectively deliver gene editors to the lung and mRNA vaccines to the spleen.

Sequence and origin of the Streptomyces intergenetic-conjugation helper plasmid pUZ8002.

Conjugation of plasmids from Escherichia coli is essential for the genetic manipulation of Streptomyces spp. To facilitate intergeneric conjugation from E. coli to Streptomyces the conjugative machinery required for genetic transfer is usually provided by the non-transferable helper plasmid, pUZ8002. Here we present the complete nucleotide sequence of pUZ8002, describe the previously undocumented creation process, and provide details of the sequence relative to the parental pUZ8 plasmid and another previously published pUZ8002 sequence.

Modulation of AAV9 Galactose Binding Yields Novel Gene Therapy Vectors and Predicts Cross-Species Differences in Glycan Avidity.

Effective use of adeno-associated viruses (AAVs) for clinical gene therapy is limited by their propensity to accumulate in and transduce the liver. This natural liver tropism is associated with severe adverse events at the high doses that can be necessary for achieving therapeutic transgene expression in extrahepatic tissues. To improve the safety and cost of AAV gene therapy, capsid engineering efforts are underway to redirect in vivo AAV biodistribution away from the liver toward disease-relevant peripheral organs such as the heart. Building on previous work, we generated a series of AAV libraries containing variations at three residues (Y446, N470, and W503) of the galactose-binding pocket of the AAV9 VP1 protein. Screening of this library in mice identified the XRH family of variants (Y446X, N470R, and W503H), the strongest of which, HRH, exhibited a 6-fold reduction in liver RNA expression and a 10-fold increase in cardiac RNA expression compared with wild-type AAV9 in the mouse. Screening of our library in a nonhuman primate (NHP) revealed reduced performance of AAV9 and two closely related vectors in the NHP liver compared with the mouse liver. Measurement of the galactose-binding capacity of our library further identified those same three vectors as the only strong galactose binders, suggesting an altered galactose presentation between the mouse and NHP liver. N-glycan profiling of these tissues revealed a 9% decrease in exposed galactose in the NHP liver compared with the mouse liver. In this work, we identified a novel family of AAV variants with desirable biodistribution properties that may be suitable for targeting extrahepatic tissues such as the heart. These data also provide important insights regarding species- and tissue-specific differences in glycan presentation that may have implications for the development and translation of AAV gene therapies.

Plasma Proteomics of Exercise Blood Pressure and Incident Hypertension.

Importance: Blood pressure response during acute exercise (exercise blood pressure [EBP]) is associated with the future risk of hypertension and cardiovascular disease (CVD). Biochemical characterization of EBP could inform disease biology and identify novel biomarkers of future hypertension. Objective: To identify protein markers associated with EBP and test their association with incident hypertension. Design, Setting, and Participants: This study assayed 4977 plasma proteins in 681 healthy participants (from 763 assessed) of the Health, Risk Factors, Exercise Training and Genetics (HERITAGE; data collection from January 1993 to December 1997 and plasma proteomics from January 2019 to January 2020) Family Study at rest who underwent 2 cardiopulmonary exercise tests. Individuals were free of CVD at the time of recruitment. Individuals with resting SBP ≥160 mm Hg or DBP ≥100 mm Hg or taking antihypertensive drug therapy were excluded from the study. The association between resting plasma protein levels to both resting BP and EBP was evaluated. Proteins associated with EBP were analyzed for their association with incident hypertension in the Framingham Heart Study (FHS; n = 1177) and validated in the Jackson Heart Study (JHS; n = 772) and Multi-Ethnic Study of Atherosclerosis (MESA; n = 1367). Proteins associated with incident hypertension were tested for putative causal links in approximately 700 000 individuals using cis-protein quantitative loci mendelian randomization (cis-MR). Data were analyzed from January 2023 to January 2024. Exposures: Plasma proteins. Main Outcomes and Measures: EBP was defined as the BP response during a fixed workload (50 W) on a cycle ergometer. Hypertension was defined as BP ≥140/90 mm Hg or taking antihypertensive medication. Results: Among the 681 participants in the HERITAGE Family Study, the mean (SD) age was 34 (13) years; 366 participants (54%) were female; 238 (35%) were self-reported Black and 443 (65%) were self-reported White. Proteomic profiling of EBP revealed 34 proteins that would not have otherwise been identified through profiling of resting BP alone. Transforming growth factor ß receptor 3 (TGFBR3) and prostaglandin D2 synthase (PTGDS) had the strongest association with exercise systolic BP (SBP) and diastolic BP (DBP), respectively (TGFBR3: exercise SBP, ß estimate, -3.39; 95% CI, -4.79 to -2.00; P = 2.33 × 10-6; PTGDS: exercise DBP ß estimate, -2.50; 95% CI, -3.29 to -1.70; P = 1.18 × 10-9). In fully adjusted models, TGFBR3 was inversely associated with incident hypertension in FHS, JHS, and MESA (hazard ratio [HR]: FHS, 0.86; 95% CI, 0.75-0.97; P = .01; JHS, 0.87; 95% CI, 0.77-0.97; P = .02; MESA, 0.84; 95% CI, 0.71-0.98; P = .03; pooled cohort, 0.86; 95% CI, 0.79-0.92; P = 6 × 10-5). Using cis-MR, genetically predicted levels of TGFBR3 were associated with SBP, hypertension, and CVD events (SBP: ß, -0.38; 95% CI, -0.64 to -0.11; P = .006; hypertension: odds ratio [OR], 0.99; 95% CI, 0.98-0.99; P < .001; heart failure with hypertension: OR, 0.86; 95% CI, 0.77-0.97; P = .01; CVD: OR, 0.84; 95% CI, 0.77-0.92; P = 8 × 10-5; cerebrovascular events: OR, 0.77; 95% CI, 0.70-0.85; P = 5 × 10-7). Conclusions and Relevance: Plasma proteomic profiling of EBP identified a novel protein, TGFBR3, which may protect against elevated BP and long-term CVD outcomes.

A prospective cohort study of factors associated with the digital cushion thickness in dairy cattle.

Key factors such as stage of lactation, parity and body fat reserves have been associated with the digital cushion thickness, however, there are discrepancies between the results of previously published studies. The objective of this study was to examine the association of stage of lactation, body fat reserves, parity, and lesion incidence with the digital cushion thickness (DCT) in a large cohort of intensively monitored cows. Across 4 UK farms, 2,352 cows were prospectively enrolled and assessed at 4 time points; before calving (T1-Precalving), immediately post-calving (T2-Calving), in early lactation (T3-Early) and late lactation (T4-Late). At each time point body condition score was recorded, the presence of sole lesions (sole ulcers and sole hemorrhage) and white line lesions were assessed by veterinarians, and an ultrasound image was taken to retrospectively measure the back-fat thickness in the pelvic (BFT) region and the digital cushion on the hind left lateral claw. Mixed effects multivariable linear regression models, with the cow as a random effect were fit to examine the association between explanatory variables and the DCT. Explanatory variables tested were farm, parity, stage of lactation, body condition score, BFT, height, the presence of a lesion at the time of measurement, the chronicity of a lesion during early lactation, predicted maximum daily milk yield and the rate of milk production rise in early lactation. Stage of lactation and farm were both associated with the DCT, however an interaction was present and this DCT pattern of change was farm dependent. Two distinct patterns emerged; one indicated the nadir to occur shortly after calving, the other indicated the nadir to occur during early lactation. Neither back fat thickness nor BCS were significantly associated with the DCT. Heifers displayed thinner digital cushions compared with multiparous cows, however, this effect was dependent on the stage of lactation, with heifers having a thinner digital cushion up until late lactation, by which time the DCT was commensurate with multiparous animals. Sole lesions and white line lesions at the time of measurement were associated with the DCT (sole lesion; Estimate: -0.07mm, 95% CI: -0.14-0.00, P = 0.039, white line lesion; Estimate: 0.28mm, 95% CI: 0.15-0.42, P < 0.001).

A parametric bootstrap approach for computing confidence intervals for genetic correlations with application to genetically determined protein-protein networks.

Genetic correlation refers to the correlation between genetic determinants of a pair of traits. When using individual-level data, it is typically estimated based on a bivariate model specification where the correlation between the two variables is identifiable and can be estimated from a covariance model that incorporates the genetic relationship between individuals, e.g., using a pre-specified kinship matrix. Inference relying on asymptotic normality of the genetic correlation parameter estimates may be inaccurate when the sample size is low, when the genetic correlation is close to the boundary of the parameter space, and when the heritability of at least one of the traits is low. We address this problem by developing a parametric bootstrap procedure to construct confidence intervals for genetic correlation estimates. The procedure simulates paired traits under a range of heritability and genetic correlation parameters, and it uses the population structure encapsulated by the kinship matrix. Heritabilities and genetic correlations are estimated using the close-form, method of moment, Haseman-Elston regression estimators. The proposed parametric bootstrap procedure is especially useful when genetic correlations are computed on pairs of thousands of traits measured on the same exact set of individuals. We demonstrate the parametric bootstrap approach on a proteomics dataset from the Jackson Heart Study.

Blood transfusion in the care of patients with visceral leishmaniasis: a review of practices in therapeutic efficacy studies.

Blood transfusion remains an important aspect of patient management in visceral leishmaniasis (VL). However, transfusion triggers considered are poorly understood. This review summarises the transfusion practices adopted in VL efficacy studies using the Infectious Diseases Data Observatory VL clinical trials library. Of the 160 studies (1980-2021) indexed in the IDDO VL library, description of blood transfusion was presented in 16 (10.0%) (n=3459 patients) studies. Transfusion was initiated solely based on haemoglobin (Hb) measurement in nine studies, combining Hb measurement with an additional condition (epistaxis/poor health/clinical instability) in three studies and the criteria was not mentioned in four studies. The Hb threshold range for triggering transfusion was 3-8 g/dL. The number of patients receiving transfusion was explicitly reported in 10 studies (2421 patients enrolled, 217 underwent transfusion). The median proportion of patients who received transfusion in a study was 8.0% (Interquartile range: 4.7% to 47.2%; range: 0-100%; n=10 studies). Of the 217 patients requiring transfusion, 58 occurred before VL treatment initiation, 46 during the treatment/follow-up phase and the time was not mentioned in 113. This review describes the variation in clinical practice and is an important initial step in policy/guideline development, where both the patient's Hb concentration and clinical status must be considered.

Genome-wide analysis in over 1 million individuals of European ancestry yields improved polygenic risk scores for blood pressure traits.

Hypertension affects more than one billion people worldwide. Here we identify 113 novel loci, reporting a total of 2,103 independent genetic signals (P < 5 × 10-8) from the largest single-stage blood pressure (BP) genome-wide association study to date (n = 1,028,980 European individuals). These associations explain more than 60% of single nucleotide polymorphism-based BP heritability. Comparing top versus bottom deciles of polygenic risk scores (PRSs) reveals clinically meaningful differences in BP (16.9 mmHg systolic BP, 95% CI, 15.5-18.2 mmHg, P = 2.22 × 10-126) and more than a sevenfold higher odds of hypertension risk (odds ratio, 7.33; 95% CI, 5.54-9.70; P = 4.13 × 10-44) in an independent dataset. Adding PRS into hypertension-prediction models increased the area under the receiver operating characteristic curve (AUROC) from 0.791 (95% CI, 0.781-0.801) to 0.826 (95% CI, 0.817-0.836, ∆AUROC, 0.035, P = 1.98 × 10-34). We compare the 2,103 loci results in non-European ancestries and show significant PRS associations in a large African-American sample. Secondary analyses implicate 500 genes previously unreported for BP. Our study highlights the role of increasingly large genomic studies for precision health research.

Genetic predisposition, modifiable lifestyles, and their joint effects on human lifespan: evidence from multiple cohort studies.

OBJECTIVE: To investigate the associations across genetic and lifestyle factors with lifespan. DESIGN: A longitudinal cohort study. SETTING: UK Biobank. PARTICIPANTS: 353 742 adults of European ancestry, who were recruited from 2006 to 2010 and were followed up until 2021. EXPOSURES: A polygenic risk score for lifespan with long (highest quintile) risk categories and a weighted healthy lifestyle score, including no current smoking, moderate alcohol consumption, regular physical activity, healthy body shape, adequate sleep duration, and a healthy diet, categorised into favourable, intermediate, and unfavourable lifestyles. MAIN OUTCOME MEASURES: Lifespan defined as the date of death or the censor date minus the date of birth. RESULTS: Of the included 353 742 participants of European ancestry with a median follow-up of 12.86 years, 24 239 death cases were identified. Participants were grouped into three genetically determined lifespan categories including long (20.1%), intermediate (60.1%), and short (19.8%), and into three lifestyle score categories including favourable (23.1%), intermediate (55.6%), and unfavourable (21.3%). The hazard ratio (HR) of death for individuals with a genetic predisposition to a short lifespan was 1.21 (95% CI 1.16 to 1.26) compared to those with a genetic predisposition to a long lifespan. The HR of death for individuals in the unfavourable lifestyle category was 1.78 (95% CI 1.71 to 1.85), compared with those in the favourable lifestyle category. Participants with a genetic predisposition to a short lifespan and an unfavourable lifestyle had 2.04 times (95% CI 1.87 to 2.22) higher rates of death compared with those with a genetic predisposition to a long lifespan and a favourable lifestyle. No multiplicative interaction was detected between the polygenic risk score of lifespan and the weighted healthy lifestyle score (p=0.10). The optimal combination of healthy lifestyles, including never smoking, regular physical activity, adequate sleep duration, and a healthy diet, was derived to decrease risk of premature death (death before 75 years). CONCLUSION: Genetic and lifestyle factors were independently associated with lifespan. Adherence to healthy lifestyles could largely attenuate the genetic risk of a shorter lifespan or premature death. The optimal combination of healthy lifestyles could convey better benefits for a longer lifespan, regardless of genetic background.

Daily Injection of the ß2 Adrenergic Agonist Clenbuterol Improved Muscle Glucose Metabolism, Glucose-Stimulated Insulin Secretion, and Hyperlipidemia in Juvenile Lambs Following Heat-Stress-Induced Intrauterine Growth Restriction.

Stress-induced fetal programming diminishes ß2 adrenergic tone, which coincides with intrauterine growth restriction (IUGR) and lifelong metabolic dysfunction. We determined if stimulating ß2 adrenergic activity in IUGR-born lambs would improve metabolic outcomes. IUGR lambs that received daily injections of saline or the ß2 agonist clenbuterol from birth to 60 days were compared with controls from pair-fed thermoneutral pregnancies. As juveniles, IUGR lambs exhibited systemic inflammation and robust metabolic dysfunction, including greater (p < 0.05) circulating TNFα, IL-6, and non-esterified fatty acids, increased (p < 0.05) intramuscular glycogen, reduced (p < 0.05) circulating IGF-1, hindlimb blood flow, glucose-stimulated insulin secretion, and muscle glucose oxidation. Daily clenbuterol fully recovered (p < 0.05) circulating TNFα, IL-6, and non-esterified fatty acids, hindlimb blood flow, muscle glucose oxidation, and intramuscular glycogen. Glucose-stimulated insulin secretion was partially recovered (p < 0.05) in clenbuterol-treated IUGR lambs, but circulating IGF-1 was not improved. Circulating triglycerides and HDL cholesterol were elevated (p < 0.05) in clenbuterol-treated IUGR lambs, despite being normal in untreated IUGR lambs. We conclude that deficient ß2 adrenergic regulation is a primary mechanism for several components of metabolic dysfunction in IUGR-born offspring and thus represents a potential therapeutic target for improving metabolic outcomes. Moreover, benefits from the ß2 agonist were likely complemented by its suppression of IUGR-associated inflammation.

Adeno-associated virus-mediated trastuzumab delivery to the central nervous system for human epidermal growth factor receptor 2+ brain metastasis.

Trastuzumab improves overall survival for HER2+ breast cancer, but its short half-life in the cerebrospinal fluid (~2-4 days) and delivery limitations restrict the ability to target HER2+ central nervous system (CNS) disease. We developed an adeno-associated virus (AAV) vector expressing a codon-optimized, ubiquitin C (UbC)-promoter-driven trastuzumab sequence (AAV9.UbC.trastuzumab) for intrathecal administration. Transgene expression was evaluated in adult Rag1 knockout mice and rhesus nonhuman primates (NHPs) after a single intracerebroventricular (ICV) or intra-cisterna magna (ICM) AAV9.UbC.trastuzumab injection, respectively, using real-time PCR, ELISA, Western blot, in situ hybridization, single-nucleus RNA sequencing, and liquid chromatography-mass spectrometry; antitumor efficacy was evaluated in brain xenografts using HER2+ breast cancer cell lines (BT-474, MDA-MB-453). Transgene expression was detected in brain homogenates of Rag1 knockout mice following a single ICV injection of AAV9.UbC.trastuzumab (1 × 1011 vector genome copies [GC]/mouse) and tumor progression was inhibited in xenograft models of breast-to-brain metastasis. In NHPs, ICM delivery of AAV9.UbC.trastuzumab (3 × 1013 GC/animal) was well tolerated (36-37 days in-life) and resulted in transgene expression in CNS tissues and cerebrospinal fluid at levels sufficient to induce complete tumor remission in MDA-MB-453 brain xenografts. With AAV9's proven clinical safety record, this gene therapy may represent a viable approach for targeting HER2 + CNS malignancies.

Safety of bone marrow derived mesenchymal stem cell extracellular vesicle injection for lumbar facet joint pain.

Aim: A 3-month pilot study to evaluate the safety of injecting a bone marrow-derived mesenchymal stem cell extracellular vesicle advanced investigational product (IP) into the lumbar facet joint space as a treatment for chronic low back pain. Methods: 20 healthy adults were treated with IP injections (0.5 ml/joint) and evaluated by three functional assessments 1, 3, 7, 14, 30, 60 and 90 days later. Results: No adverse effects or complications occurred across the 3-month follow-up. There were no reports of worsening pain. After 3 months group average scores improved significantly (p < 0.0001) in the Severity Index (65.04%), Interference Index (72.09%) and Oswestry Disability Index (58.43%) assessments. Conclusion: IP injections were safe and associated with significant functional improvements.

What is this article about? Bone marrow mesenchymal stem cell derived extracellular vesicles (BM-MSC EV), a novel biologic therapeutic candidate, are a safe and promising therapeutic intervention for patients with lumbar facet joint pain, a malady that manifests as persistent low back pain (LBP). 20 adult subjects with lumbar facet joint pain received a single injection of BM-MSC EV investigational product in the lumbar facet joint space. What were the results? Follow-up was conducted through in-office and virtual visits that included outcome measures to determine the safety and efficacy of this therapy. By the 3-month end point, follow-up was successful, and no complications or adverse events were noted. Significant improvements in all three assessments of pain and disability occurred throughout the study. What do the results of the study mean? The results are promising and suggest that BM-MSC EV may represent a revolutionary treatment option with durable efficacy and minimal safety risks. Randomized, controlled clinical studies into the application of BM-MSC EV in lumbar facet joint pain should be pursued to confirm the potential benefits of this novel intervention.

Electrophysiological Characterization of Subclinical and Overt Hypertrophic Cardiomyopathy by Magnetic Resonance Imaging-Guided Electrocardiography.

BACKGROUND: Ventricular arrhythmia in hypertrophic cardiomyopathy (HCM) relates to adverse structural change and genetic status. Cardiovascular magnetic resonance (CMR)-guided electrocardiographic imaging (ECGI) noninvasively maps cardiac structural and electrophysiological (EP) properties. OBJECTIVES: The purpose of this study was to establish whether in subclinical HCM (genotype [G]+ left ventricular hypertrophy [LVH]-), ECGI detects early EP abnormality, and in overt HCM, whether the EP substrate relates to genetic status (G+/G-LVH+) and structural phenotype. METHODS: This was a prospective 211-participant CMR-ECGI multicenter study of 70 G+LVH-, 104 LVH+ (51 G+/53 G-), and 37 healthy volunteers (HVs). Local activation time (AT), corrected repolarization time, corrected activation-recovery interval, spatial gradients (GAT/GRTc), and signal fractionation were derived from 1,000 epicardial sites per participant. Maximal wall thickness and scar burden were derived from CMR. A support vector machine was built to discriminate G+LVH- from HV and low-risk HCM from those with intermediate/high-risk score or nonsustained ventricular tachycardia. RESULTS: Compared with HV, subclinical HCM showed mean AT prolongation (P = 0.008) even with normal 12-lead electrocardiograms (ECGs) (P = 0.009), and repolarization was more spatially heterogenous (GRTc: P = 0.005) (23% had normal ECGs). Corrected activation-recovery interval was prolonged in overt vs subclinical HCM (P < 0.001). Mean AT was associated with maximal wall thickness; spatial conduction heterogeneity (GAT) and fractionation were associated with scar (all P < 0.05), and G+LVH+ had more fractionation than G-LVH+ (P = 0.002). The support vector machine discriminated subclinical HCM from HV (10-fold cross-validation accuracy 80% [95% CI: 73%-85%]) and identified patients at higher risk of sudden cardiac death (accuracy 82% [95% CI: 78%-86%]). CONCLUSIONS: In the absence of LVH or 12-lead ECG abnormalities, HCM sarcomere gene mutation carriers express an aberrant EP phenotype detected by ECGI. In overt HCM, abnormalities occur more severely with adverse structural change and positive genetic status.

In situ combinatorial synthesis of degradable branched lipidoids for systemic delivery of mRNA therapeutics and gene editors.

The ionizable lipidoid is a key component of lipid nanoparticles (LNPs). Degradable lipidoids containing extended alkyl branches have received tremendous attention, yet their optimization and investigation are underappreciated. Here, we devise an in situ construction method for the combinatorial synthesis of degradable branched (DB) lipidoids. We find that appending branch tails to inefficacious lipidoids via degradable linkers boosts mRNA delivery efficiency up to three orders of magnitude. Combinatorial screening and systematic investigation of two libraries of DB-lipidoids reveal important structural criteria that govern their in vivo potency. The lead DB-LNP demonstrates robust delivery of mRNA therapeutics and gene editors into the liver. In a diet-induced obese mouse model, we show that repeated administration of DB-LNP encapsulating mRNA encoding human fibroblast growth factor 21 alleviates obesity and fatty liver. Together, we offer a construction strategy for high-throughput and cost-efficient synthesis of DB-lipidoids. This study provides insights into branched lipidoids for efficient mRNA delivery.