Resetting of the Human Circadian Melatonin Rhythm by Ambient Hypoxia.

Circadian clocks in the body drive daily cycles in physiology and behavior. A master clock in the brain maintains synchrony with the environmental day-night cycle and uses internal signals to keep clocks in other tissues aligned. Work in cell cultures uncovered cyclic changes in tissue oxygenation that may serve to reset and synchronize circadian clocks.

Superior transseptal versus left atriotomy approaches in isolated mitral valve surgery.

Objective: The superior transseptal approach to mitral valve surgery offers improved exposure compared with left atriotomy; however, concerns remain regarding postoperative arrhythmias and pacemaker placement. This study investigates intraoperative parameters and postoperative outcomes in these approaches.

Methods: Retrospective review of 259 adults undergoing isolated mitral valve repair or replacement over a 10-year period was performed.

Effect of magnetic field strength and segmentation variability on the reproducibility and repeatability of radiomic texture features in cardiovascular magnetic resonance parametric mapping.

Our study aims to assess the robustness of myocardial radiomic texture features (RTF) to segmentation variability and variations across scanners with different field strengths, addressing concerns about reliability in clinical practices. We conducted a retrospective analysis on 45 pairs of CMR T1 maps from 15 healthy volunteers using 1.5 T and 3 T Siemens scanners.

Temperature Induced Unfolding and Compaction of Cytochrome in the Same Aqueous Solutions.

Most conventional methods used to measure protein melting temperatures reflect changes in structure between different conformational states and are typically fit to a two-state model. Population abundances of distinct conformations were measured using variable-temperature electrospray ionization ion mobility mass spectrometry to investigate the thermally induced unfolding of the model protein cytochrome . Nineteen conformers formed at high temperature have elongated structures, consistent with unfolded forms of this protein.