The SARS-CoV2 envelope differs from host cells, exposes procoagulant lipids, and is disrupted in vivo by oral rinses.

The lipid envelope of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an essential component of the virus; however, its molecular composition is undetermined. Addressing this knowledge gap could support the design of antiviral agents as well as further our understanding of viral-host protein interactions, infectivity, pathogenicity, and innate immune system clearance. Lipidomics revealed that the virus envelope comprised mainly phospholipids (PLs), with some cholesterol and sphingolipids, and with cholesterol/phospholipid ratio similar to lysosomes. Unlike cellular membranes, procoagulant amino-PLs were present on the external side of the viral envelope at levels exceeding those on activated platelets. Accordingly, virions directly promoted blood coagulation. To investigate whether these differences could enable selective targeting of the viral envelope in vivo, we tested whether oral rinses containing lipid-disrupting chemicals could reduce infectivity. Products containing PL-disrupting surfactants (such as cetylpyridinium chloride) met European virucidal standards in vitro; however, components that altered the critical micelle concentration reduced efficacy, and products containing essential oils, povidone-iodine, or chlorhexidine were ineffective. This result was recapitulated in vivo, where a 30-s oral rinse with cetylpyridinium chloride mouthwash eliminated live virus in the oral cavity of patients with coronavirus disease 19 for at least 1 h, whereas povidone-iodine and saline mouthwashes were ineffective. We conclude that the SARS-CoV-2 lipid envelope i) is distinct from the host plasma membrane, which may enable design of selective antiviral approaches; ii) contains exposed phosphatidylethanolamine and phosphatidylserine, which may influence thrombosis, pathogenicity, and inflammation; and iii) can be selectively targeted in vivo by specific oral rinses.

Revised sample preparation for the analysis of oxysterols by enzyme-assisted derivatisation for sterol analysis (EADSA).

Sterols, and specifically oxysterols, play important roles in the biosynthesis of bile acids and steroid hormones as well as possessing biological activities in their own right. Analysis of oxysterols is complicated due to their low abundance in biological systems and poor ionisation characteristics in mass spectrometry. Over the past decade, we have developed a liquid chromatography-mass spectrometry method termed enzyme-assisted derivatisation for sterol analysis (EADSA). Our derivatisation procedure relies on two solid-phase extraction steps to (i) separate cholesterol from oxysterols and (ii) remove excess derivatisation reagents. Recent inter-batch variation in C18 reversed-phase cartridges has led us to experiment with alternative columns. Here, we present our findings and report an improved sample preparation procedure using polymeric hydrophilic-lipophilic balanced reversed-phase cartridges.

Reactivation of herpes simplex virus after liver transplantation.

Reactivation of herpes simplex virus (HSV) after liver transplantation occurs but the incidence and clinical significance are unknown. We recruited 12 consecutive male patients listed for liver transplantation and positive for HSV antibody. HSV polymerase chain reaction was performed on mouth and penile swabs before and at days 5 and 10 after transplant. Data were recorded regarding clinical evidence of HSV infection, degree of immune suppression, length of intensive care stay, and use of antiviral agents. Five out of twelve patients (42%) had evidence of oral reactivation after transplant although only one had clinical manifestations. Genital reactivation was not seen. Reactivation did not correlate with immune suppression but duration of intensive care stay was a possible risk factor. Ganciclovir prescribed for cytomegalovirus prophylaxis in one patient was ineffective. Oral reactivation of HSV after liver transplantation is common; although clinical significance appears low in this small series, routine testing could be implemented readily.

A retrospective study assessing fully covered metal stents as first-line management for malignant biliary strictures.

OBJECTIVES: Fully covered self-expanding metal stents (FCSEMS) constitute the first type of metal stent that can easily be removed endoscopically and/or intraoperatively, which may be advantageous in the management of distal malignant biliary strictures (DMBS). To assess the efficacy of FCSEMS as first-line treatment for DMBS, we compared patency, survival and complication rates between FCSEMS, uncovered self-expanding metal stents (USEMS) and plastic stents (PS). METHODS: This was a multicentre retrospective study of 315 consecutive patients with DMBS, who underwent endoscopic retrograde cholangiopancreatography and stenting (FCSEMS, USEMS or PS) at two hospitals between 1 January 2007 and 31 December 2013. Stent patency and patient survival were compared using the Kaplan-Meier method; complication rates were compared using Fisher's exact test; and Cox regression analysis was used to screen for confounding factors. RESULTS: FCSEMS were associated with prolonged stent patency (median=145 days) compared with USEMS (median=110 days, P<0.003) and PS (median=34 days, P<0.001). Biliary sepsis rates were lower for FCSEMS compared with PS (4.7 vs. 17.8%, P=0.02), whereas pancreatitis rates were higher for FCSEMS compared with USEMS (7.8 vs. 1.0%, P=0.04), but not PS (2.6%, P=NS). CONCLUSION: The use of FCSEMS as first-line management for DMBS is associated with longer patency and reduced complication rates compared with the use of PS. However, the higher rate of pancreatitis compared with USEMS requires further evaluation in a large randomized controlled trial.

Observation of an intact noncovalent homotrimer of detergent-solubilized rat microsomal glutathione transferase-1 by electrospray mass spectrometry.

Microsomal glutathione transferase-1 (MGST1) is a membrane-bound enzyme involved in the detoxification of xenobiotics and the protection of cells against oxidative stress. The proposed active form of the enzyme is a noncovalently associated homotrimer that binds one substrate glutathione molecule/trimer. In this study, this complex has been directly observed by electrospray mass spectrometry analysis of active rat liver MGST1 reconstituted in a minimum amount of detergent. The measured mass of the homotrimer is 53 kDa, allowing for the mass of three MGST molecules in complex with one glutathione molecule. Collision-induced dissociation of the trimer complex resulted in the formation of monomer and homodimer ion species. Two distinct species of homodimer were observed, one unliganded and one identified as a homodimer.glutathione complex. Activation of the enzyme by N-ethylmaleimide through modification of Cys(49) (Svensson, R., Rinaldi, R., Swedmark, S., and Morgenstern, R. (2000) Biochemistry 39, 15144-15149) was monitored by the observation of an appropriate increase in mass in both the denatured monomeric and native trimeric forms of MGST1. Together, the data correspond well with the proposed functional organization of MGST1. These results also represent the first example of direct electrospray mass spectrometry analysis of a detergent-solubilized multimeric membrane protein complex in its native state.