Ephrin-B1 regulates the adult diastolic function through a late postnatal maturation of cardiomyocyte surface crests

The rod-shaped adult cardiomyocyte (CM) harbors a unique architecture of its lateral surface with periodic crests, relying on the presence of subsarcolemmal mitochondria (SSM) with unknown role. Here, we investigated the development and functional role of CM crests during the postnatal period. We found in rodents that CM crest maturation occurs late between postnatal day 20 (P20) and P60 through both SSM biogenesis, swelling and crest-crest lateral interactions between adjacent CM, promoting tissue compaction. At the functional level, we showed that the P20-P60 period is dedicated to the improvement of relaxation. Interestingly, crest maturation specifically contributes to an atypical CM hypertrophy of its short axis, without myofibril addition, but relying on CM lateral stretching. Mechanistically, using constitutive and conditional CM-specific knock-out mice, we identified ephrin-B1, a lateral membrane stabilizer, as a molecular determinant of P20-P60 crest maturation, governing both the CM lateral stretch and the diastolic function, thus highly suggesting a link between crest maturity and diastole. Remarkably, while young adult CM-specific Efnb1 KO mice essentially exhibit an impairment of the ventricular diastole with preserved ejection fraction and exercise intolerance, they progressively switch toward systolic heart failure with 100% KO mice dying after 13 months, indicative of a critical role of CM-ephrin-B1 in the adult heart function. This study highlights the molecular determinants and the biological implication of a new late P20-P60 postnatal developmental stage of the heart in rodents during which, in part, ephrin-B1 specifically regulates the maturation of the CM surface crests and of the diastolic function.

Gunshot residue detection in stagnant water: SEM-EDX or ICP-MS? A preliminary study

The identification of gunshot residue (GSR) on wounds enables the differentiation of entry and exit wounds. Unfortunately, studies analyzing GSR on degraded bodies have been poorly documented, and no data exist regarding GSR detection after stagnant water immersion. The aim of this preliminary experimental study was to detect GSR on wounds altered in stagnant water, using scanning electron microscopy coupled with energy-dispersive X (SEM-EDX) and inductively coupled plasma mass spectrometry (ICP-MS). Shots were performed on sheep limbs with a 22LR at a distance of 20 cm. The limbs were then submerged in stagnant water and analyzed on days 0, 6, and 14. SEM-EDX was performed on previously dehydrated wounds. For ICP-MS analysis, the wounds were rubbed with a cotton swab that was then analyzed. In the SEM studies, a higher number of particles were detected in entry wounds compared to exit wounds under every set of experimental conditions. Unfortunately, SEM-EDX failed to detect GSR particles, even on day 0. ICP-MS enabled the detection of Pb, Sb, and Ba at every stage with higher quantities on entry than in exit. These elements remained detectable following limb immersion. ICP-MS enabled differentiate entry from exit wounds, even after immersion in stagnant water. Nevertheless, when manually swabbing the wounds, quantities of matter collected is highly variable. ICP-MS is a more suitable technique than SEM-EDX for GSR identification of wounds after decomposition in stagnant water; however, standardization is needed.

Finding of Hyperostosis Frontalis Interna During the Autopsy Procedure: Forensic Issues

Hyperostosis frontalis interna is a common phenomenon, which may have been overrated in its significance in the past, and may, currently be underrated in its significance. We present three cases of hyperostosis frontalis interna found during medicolegal autopsies and discuss their forensic considerations. The patients were all middle-aged women with metabolic and endocrine manifestations and psychiatric ailments; thickening of the inner table of the frontal bone of the skull was found during each autopsy. We describe the relationship between hyperostosis frontalis interna, metabolic manifestations, and neuropsychiatric symptoms as part of Morgagni-Stewart-Morel syndrome. There is still considerable disagreement in the scientific community as to whether this syndrome is a clinical entity. Nonetheless, awareness of Morgagni-Stewart-Morel syndrome can be of help in understanding the circumstances surrounding death. In some other cases, hyperostosis frontalis interna could be used by forensic pathologists as criteria for sexing and aging a skeleton.