Effects of Amyloid Beta (Aß) Oligomers on Blood-Brain Barrier Using a 3D Microfluidic Vasculature-on-a-Chip Model.

The disruption of the blood-brain barrier (BBB) in Alzheimer's Disease (AD) is largely influenced by amyloid beta (Aß). In this study, we developed a high-throughput microfluidic BBB model devoid of a physical membrane, featuring endothelial cells interacting with an extracellular matrix (ECM). This paper focuses on the impact of varying concentrations of Aß1-42 oligomers on BBB dysfunction by treating them in the luminal. Our findings reveal a pronounced accumulation of Aß1-42 oligomers at the BBB, resulting in the disruption of tight junctions and subsequent leakage evidenced by a barrier integrity assay. Additionally, cytotoxicity assessments indicate a concentration-dependent increase in cell death in response to Aß1-42 oligomers (LC50 ~ 1 µM). This study underscores the utility of our membrane-free vascular chip in elucidating the dysfunction induced by Aß with respect to the BBB.

Near-Infrared Spectroscopy (NIRS) for Cerebral and Tissue Oximetry: Analysis of Evolving Applications.

THE USE OF NEAR-INFRARED SPECTROSCOPY (NIRS) has increased significantly worldwide in the past decade. This technology, first described more than 40 years ago, is based on the fact that near-infrared light is able to penetrate biologic tissue and can obtain real-time, noninvasive information on tissue oxygenation and metabolism. In the clinical setting, NIRS has been able to provide clinicians potentially valuable information in patients with impaired microcirculations (systemic and cerebral). Near-infrared spectroscopy has progressed beyond assessment of brain oxygenation to monitor local tissue and muscle oxygenation and perfusion. This review analyzes the published data and provides the clinician a comprehensive account of the perioperative utility of NIRS in cardiac, vascular and thoracic surgery, as well as its increasing role in tissue/muscle oxygenation monitoring.

Nontransvenous Cardiovascular Implantable Electronic Device Technology-A Review for the Anesthesiologist.

There has been a recent shift in bradycardia pacing and defibrillation therapy to leadless pacemakers and extrathoracic cardioverter-defibrillator technology due to complications associated with transvenous devices. These innovations have implications for anesthesia care, as these novel devices have design and functionality features different from transvenous devices. Current perioperative guidelines do not address management of leadless pacemakers and the subcutaneous implantable cardioverter-defibrillator, although implantation rates are increasing globally. This article addresses the features and capabilities of nontransvenous cardiac implantable electronic devices, such as the Micra and the subcutaneous implantable cardioverter-defibrillator, and provides guidance for perioperative management.

The Year in Electrophysiology: Selected Highlights From 2020.

This article is the third in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the Editor-in-Chief Dr. Kaplan, the Associate Editor-in-Chief Dr. Augoustides, and the editorial board for the opportunity to continue this series; namely, the highlights of the year that pertain to electrophysiology in relation to cardiothoracic and vascular anesthesia. This third article focuses on the convergent procedure, His-bundle pacing, a comparison of subcutaneous and transvenous defibrillator therapies, the 2020 practice advisory update for the perioperative management of patients with cardiac implantable electronic devices, and a technology update regarding the Micra AV (Medtronic, Moundsview, MN), the EMPOWER leadless pacemaker (Boston Scientific, Marlborough, MA), WiSE-CRT (EBR Systems, Sunnyvale, CA), the Extravascular Implantable Cardioverter Defibrillator (Medtronic, Moundsview, MN), and the BAROSTIM NEO (CVRx Inc, Minneapolis, MN).

Abnormal platelet aggregation in idiopathic pulmonary arterial hypertension: role of nitric oxide.

Idiopathic pulmonary arterial hypertension (IPAH) is a rare and progressive disease. Several processes are believed to lead to the fatal progressive pulmonary arterial narrowing seen in IPAH including vasoconstriction, cellular proliferation inflammation, vascular remodeling, abnormalities in the lung matrix, and in situ thrombosis. Nitric oxide (NO) produced by NO synthases (NOS) is a potent vasodilator and plays important roles in many other processes including platelet function. Reduced NO levels in patients with IPAH are known to contribute to the development of pulmonary hypertension and its complications. Platelet defects have been implied in IPAH, but original research supporting this hypothesis has been limited. Normal platelets are known to have NOS activity, but little is known about NOS expression and NO production by platelets in patients with IPAH. Here we characterized the phenotype of the platelets in IPAH and show a defect in their ability to be activated in vitro by thrombin receptor activating protein but not adenosine diphosphate. We also show that endothelial NOS (eNOS) levels in these platelets are reduced and demonstrate that NO is an important regulator of platelet function. Thus reduced levels of eNOS in platelets could impact their ability to regulate their own function appropriately.