Chest Pain With Significantly Elevated Troponins: Be Wary of False Positives.

High-sensitivity cardiac troponins are considered a gold standard for diagnosing acute myocardial infarction and myocardial injury. However, the occurrence of false positives needs to be kept in mind.  We describe the clinical challenges in diagnosing a 45-year-old woman who repeatedly presented to the emergency department with atypical chest pain and extremely elevated high sensitivity troponin I (HsTnI), despite normal imaging including cardiac MRIs and invasive coronary angiograms, on multiple occasions.

High sensitivity direct magnetic field detection based metrology for ultra-thin magnetic films and Li-ion cells.

Ultra-low magnetic field sensing is emerging as a tool for materials' diagnostics, particularly for the operando studies of electrochemical systems. A magnetic metrology system having the capability of sensing fields as low as ∼1.88 pT has been setup for such studies using a commercial atomic magnetometer.

An integrated picture of the structural pathways controlling the heart performance.

The regulation of heart function is attributed to a dual filament mechanism: i) the Ca-dependent structural changes in the regulatory proteins of the thin, actin-containing filament making actin available for myosin motor attachment, and ii) the release of motors from their folded (OFF) state on the surface of the thick filament allowing them to attach and pull the actin filament. Thick filament mechanosensing is thought to control the number of motors switching ON in relation to the systolic performance, but its molecular basis is still controversial. Here, we use high spatial resolution X-ray diffraction data from electrically paced rat trabeculae and papillary muscles to provide a molecular explanation of the modulation of heart performance that calls for a revision of the mechanosensing hypothesis.

Load-dependence of the activation of myosin filaments in heart muscle.

Contraction of heart muscle requires activation of both the actin and myosin filaments. The mechanism of myosin filament activation is unknown, but the leading candidate hypothesis is direct mechano-sensing by the filaments. Here, we tested this hypothesis by activating intact trabeculae from rat heart by electrical stimulation under different loads and measuring myosin filament activation by X-ray diffraction.