The recent discovery of heterozygous human mutations that truncate full-length titin (TTN, an abundant structural, sensory, and signaling filament in muscle) as a common cause of end-stage dilated cardiomyopathy (DCM) provides new prospects for improving heart failure management. However, realization of this opportunity has been hindered by the burden of TTN truncating variants (TTNtv) in the general population and uncertainty about their consequences in health or disease. To elucidate the effects of TTNtv, we coupled TTN gene sequencing with cardiac phenotyping in 5,267 individuals across the spectrum of cardiac physiology, and integrated these data with RNA and protein analyses of human heart tissues. We report diversity of TTN isoform expression in the heart, define the relative inclusion of TTN exons in different isoforms, and demonstrate that these data, coupled with TTNtv position, provide a robust strategy to discriminate pathogenic from benign TTNtv. We show that TTNtv is the most common genetic cause for DCM in ambulant patients in the community, identify clinically important manifestations of TTNtv-positive DCM, and define the penetrance and outcomes of TTNtv in the general population. By integrating genetic, transcriptome, and protein analyses we provide evidence for a length-dependent, dominant negative mechanism of disease. These data inform diagnostic criteria and management strategies for TTNtv-positive DCM patients and for TTNtv that are identified as incidental findings.

Variations in the treatment of polymyxin B and polymyxin E (colistin) with formaldehyde and sodium bisulphite produce sulphomethyl derivatives which differ quantitatively in acute toxicity and in antibacterial activities in vitro and in vivo. The acute intravenous LD50 values of some sixty samples of these derivatives range from six-to more than eighty-fold those of the parent antibiotics; the in vitro antibacterial activities range from 2 to 12% and the in vivo activities from 20 to 50% of those of the parent antibiotics, with the most toxic derivatives showing the highest activities. When short and prolonged incubation methods are used, assays of the derivatives in solutions of different ages and of blood collected from man and dog after intramuscular injection, show that the antibacterial activities of these sulphomethyl derivatives depend on reversion to the unsubstituted form, and that the differences in the activities are due to variations in stability. These conclusions are supported by comparison of these sulphomethyl derivatives with stable acetyl derivatives. The lower in vivo activity is due, at least partly, to the high renal excretion of the substituted form. Electrophoresis shows that the derivatives are composite, the components corresponding to mono-to pentasulphomethyl polymyxin. Pain at the injection site is the most troublesome side-effect of polymyxin therapy, and this is avoided with these derivatives. In rats injected with quantities some twenty-times the usual human dose, the derivatives cause transitory decrease in urinary output and transitory proteinuria. After intramuscular injection of these derivatives into dogs, no antibiotic is detectable in the cerebrospinal fluid and concentrations present in the bile are not significantly different from those after injection of the parent antibiotic. When injected intracisternally into these animals, derivatives are less toxic than the parent compounds. These studies show that acute intravenous toxicity is a useful index of therapeutic efficiency and that derivatives with intravenous LD50 values of about 100 mg/kg are the most satisfactory ones. Because activity depends on reversion to the parent antibiotic, the use of these derivatives for topical application is contraindicated.

Substituted benzaldehydes have been designed to bind preferentially to the oxy conformation of human haemoglobin at a site between the amino terminal residues of the α‐subunits. Such compounds should stabilize the oxygenated form of haemoglobin and thereby increase its oxygen affinity. The compounds produce the expected effect, left‐shifting the oxygen saturation curve of dilute haemoglobin solutions and of whole blood, although the binding pattern to haemoglobin is more complex than envisaged by the design hypothesis. The predicted best compound is also a potent inhibitor, at low oxygen pressure, of the sickling of erythrocytes from patients homozygous for sickle cell disease, and may prove to be a clinically useful anti‐sickling agent.

(ACMG) are generic and require disease-specific refinement. Here we developed CardioClassifier (http://www.cardioclassifier.org), a semiautomated decision-support tool for inherited cardiac conditions (ICCs).Methods: CardioClassifier integrates data retrieved from multiple sources with user-input case-specific information, through an interactive interface, to support variant interpretation. Combining disease-and gene-specific knowledge with variant observations in large cohorts of cases and controls, we refined 14 computational ACMG criteria and created three ICC-specific rules.Results: We benchmarked CardioClassifier on 57 expertly curated variants and show full retrieval of all computational data, concordantly activating 87.3% of rules. A generic annotation tool identified fewer than half as many clinically actionable variants (64/219 vs. 156/219, Fisher's P = 1.1 × 10 − 18 ), with important false positives, illustrating the critical importance of disease and gene-specific annotations. CardioClassifier identified putatively disease-causing variants in 33.7% of 327 cardiomyopathy cases, comparable with leading ICC laboratories. Through addition of manually curated data, variants found in over 40% of cardiomyopathy cases are fully annotated, without requiring additional userinput data. Conclusion:CardioClassifier is an ICC-specific decision-support tool that integrates expertly curated computational annotations with case-specific data to generate fast, reproducible, and interactive variant pathogenicity reports, according to best practice guidelines.