PM-IRRAS Studies of DMPC Bilayers Supported on Au(111) Electrodes Modified with Hydrophilic Monolayers of Thioglucose.

A phospholipid bilayer composed of 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine (d54-DMPC) was deposited onto the Au(111) electrode modified with a self-assembled monolayer of 1-thio-ß-d-glucose (ß-Tg) via the Langmuir-Blodgett and Langmuir-Schaefer (LB-LS) techniques. Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) measurements were used to characterize structural and orientational changes in this model biological membrane on a hydrophilic surface modified gold electrode. The results of the spectroscopic measurements showed that the tilt angle of acyl chains obtained for deuterated DMPC bilayers supported on the ß-Tg-modified gold is significantly lower than that reported previously for DMPC bilayers deposited directly on Au(111) electrodes. Moreover, tilt angles of ∼18° were obtained for d54-DMPC bilayers on ß-Tg self-assembled monolayers (SAMs) at positive potentials, which are similar to the values calculated for h-DMPC deposited on bare gold in the desorbed state and to those observed for a stack of hydrated DMPC bilayers. This data confirms that the ß-thioglucose SAM promotes the formation of a water cushion that separates the phospholipid bilayer from the metal surface. As a result, the DMPC polar heads are not in direct contact with the electrode and can adopt a zigzag configuration, which strengthens the chain-chain interactions and allows for an overall decrease in the tilt of the acyl chains. These novel supported model membranes may be especially useful in studies pertaining to the incorporation of peptides and proteins into phospholipid bilayers.

Massive biventricular thrombi complicating new-onset heart failure in a patient with suspected COVID-19.

The World Health Organization nominated SARS-CoV-2 as the cause of the Coronavirus Disease 2019 (COVID-19) and has been granted as a pandemic. COVID-19 is an emerging threat due to the risk of microvascular, venous, and arterial thrombosis, thereby exacerbating organ injury and mortality. Although the exact mechanism of extensive thromboembolism and myocardial injury caused by SARS-CoV-2 is not illuminated, it is clear that COVID-19 related hypercoagulation increasing the fatality of the disease. Herein, we reported a patient with extensive biventricular thrombi along with the new-onset severe systolic dysfunction as an unusual catastrophic presentation of COVID-19. In our patient, there was both a right atrial "clot in transit" from his DVT as well as extensive muralized biventricular thrombus from severe global hypokinesis. We believe that the hypercoagulable state of his COVID-19 infection, along with severe systolic dysfunction, caused this unusual presentation. Although the hypercoagulable state of COVID-19 is well recognized, there have not been any reported cases of extensive de-novo intracardiac thrombus as of yet. We urge awareness of severe and potentially fatal extensive thrombosis and cardiac failure as the initial clinical presentation of possible SARS-CoV-2. .

Intracranial Tuberculoma Mimicking Neurosarcoidosis: A Clinical Challenge.

Central nervous system (CNS) tuberculosis is a rare manifestation of all tuberculosis presentations. The incidence of brain tuberculoma is increasing in developed countries due to HIV infection and immigration from tuberculosis-endemic countries. Symptoms and radiologic findings of CNS tuberculosis can be non-specific and lead to misdiagnosis or mistreatment. Intracranial tuberculoma can present with a seizure, intracranial hypertension, or focal neurologic symptoms. In our case, the diagnosis was challenging between neurosarcoidosis and intracranial tuberculoma due to inconclusive results of stereotactic brain biopsy and clinical presentation. The pathology result of the open brain biopsy revealed non-caseating granuloma. Finally, we were able to diagnose intracranial tuberculoma following acid-fast bacilli culture results of open brain biopsy. This report highlights the importance of including intracranial tuberculoma in the differential diagnosis of cerebral space-occupying lesions, even in patients with negative laboratory findings of tuberculosis.