Targeting the Complement Serine Protease MASP-2 as a Therapeutic Strategy for Coronavirus Infections

MASP-2, mannose-binding protein-associated serine protease 2, is a key enzyme in the lectin pathway of complement activation. Hyperactivation of this protein by human coronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2 has been found to contribute to aberrant complement activation in patients, leading to aggravated lung injury with potentially fatal consequences. This hyperactivation is triggered in the lungs through a conserved, direct interaction between MASP-2 and coronavirus nucleocapsid (N) proteins. Blocking this interaction with monoclonal antibodies and interfering directly with the catalytic activity of MASP-2, have been found to alleviate coronavirus-induced lung injury both in vitro and in vivo. In this study, a virtual library of 8736 licensed drugs and clinical agents has been screened in silico according to two parallel strategies. The first strategy aims at identifying direct inhibitors of MASP-2 catalytic activity, while the second strategy focusses on finding protein-protein interaction inhibitors (PPIs) of MASP-2 and coronaviral N proteins. Such agents could represent promising support treatment options to prevent lung injury and reduce mortality rates of infections caused by both present and future-emerging coronaviruses. Forty-six drug repurposing candidates were purchased and, for the ones selected as potential direct inhibitors of MASP-2, a preliminary in vitro assay was conducted to assess their interference with the lectin pathway of complement activation. Some of the tested agents displayed a dose-response inhibitory activity of the lectin pathway, potentially providing the basis for a viable support strategy to prevent the severe complications of coronavirus infections.     

Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.     

Evaluating the Tongue-Hold Maneuver Using High-Resolution Manometry and Electromyography

The tongue-hold maneuver is a widely used clinical technique designed to increase posterior pharyngeal wall movement in individuals with dysphagia. It is hypothesized that the tongue-hold maneuver results in increased contraction of the superior pharyngeal constrictor. However, an electromyographic study of the pharynx and tongue during the tongue-hold is still needed to understand whether and how swallow muscle activity and pressure may change with this maneuver. We tested eight healthy young participants using simultaneous intramuscular electromyography with high-resolution manometry during three task conditions including (a) saliva swallow without maneuver, (b) saliva swallow with the tongue tip at the lip, and (c) saliva swallow during the tongue-hold maneuver. We tested the hypothesis that tongue and pharyngeal muscle activity would increase during the experimental tasks, but that pharyngeal pressure would remain relatively unchanged. We found that the pre-swallow magnitude of tongue, pharyngeal constrictor, and cricopharyngeus muscle activity increased. During the swallow, the magnitude and duration of tongue and pharyngeal constrictor muscle activity each increased. However, manometric pressures and durations remained unchanged. These results suggest that increased superior pharyngeal constrictor activity may serve to maintain relatively stable pharyngeal pressures in the absence of posterior tongue movement. Thus, the tongue-hold maneuver may be a relatively simple but robust example of how the medullary swallow center is equipped to dynamically coordinate actions between tongue and pharynx. Our findings emphasize the need for combined modality swallow assessment to include high-resolution manometry and intramuscular electromyography to evaluate the potential benefit of the tongue-hold maneuver for clinical populations.     

Barriers and facilitators to linkage to care and ART initiation in the setting of high ART coverage in Botswana

ABSTRACT

We conducted a qualitative study using focus groups and in-depth interviews to explore barriers to and facilitators of linkage-to-care and antiretroviral treatment (ART) initiation in Botswana. Participants were selected from communities receiving interventions through the Ya Tsie Study. Fifteen healthcare providers and 49 HIV-positive individuals participated. HIV-positive participants identified barriers including stigma, discrimination and overcrowded clinics, and negative staff attitudes; personal factors, such as a lack of acceptance of one’s HIV status, non-disclosure, and gender differences; along with lack of social/family support, and certain religious beliefs. Healthcare providers cited delayed test results, poverty, and transport difficulties as additional barriers. Major facilitators were support from healthcare providers, including home visits, social support, and knowing the benefits of ART. Participants were highly supportive of universal ART as a personal health measure. Our results highlighted a persistent structural health facility barrier: HIV-positive patients expressed strong discontent with HIV care/treatment being delivered differently than routine healthcare, feeling inconvenienced and stigmatized by separately designated locations and days of service. This barrier was particularly problematic for highly mobile persons. Addressing this structural barrier, which persists even in the context of high ART uptake, could bring gains in willingness to initiate ART and improved adherence in Botswana and elsewhere.     

Blood pressure regulation VII. The “morning surge” in blood pressure: measurement issues and clinical significance

In keeping with this review-series theme, we question whether the morning surge in blood pressure (MSBP) is a benign response to the physiological challenges during the first 3 h after waking, or is it clinically important? Therefore, we scrutinise the circadian-related mechanisms, the measurement methods and the prognostic value of the MSBP. The MSBP is relatively small (<2 mmHg) under constant routine conditions. Nevertheless, the blood pressure response to exercise can be 8–14 mm Hg greater in the morning vs. afternoon, even when prior sleep is controlled. Systematic bias between MSBP methods can be >10 mmHg. The “sleep-trough” method provides the largest MSBP (≈25 mmHg), but the sensitivity of MSBP to a treatment/intervention depends largely on its repeatability. The repeatability standard deviation (SD) for most MSBP methods is ≈8 mm Hg. While the magnitude of this SD precludes the use of MSBP for diagnostic decisions on individual patients, sample sizes for future intervention studies may be feasible, depending on the minimal clinically important difference in MSBP. This difference is somewhat unclear given that a large MSBP has recently been reported to predict a reduced, rather than a higher, risk of cardiovascular disease, although this particular study has been criticised. The MSBP is also naturally correlated to changes in physical activity and nocturnal “dipping” status. Therefore, it is important to account for these potential confounders of the MSBP, so that more precise knowledge about its clinical significance is gained, thereby providing a sound rationale for physiological investigation and translational research.     

SUDEP classification: Discordances between forensic investigators and epileptologists

We compared sudden unexpected death in epilepsy (SUDEP) diagnosis rates between North American SUDEP Registry (NASR) epileptologists and original death investigators, to determine degree and causes of discordance. In 220 SUDEP cases with post-mortem examination, we recorded the epileptologist adjudications and medical examiner- and coroner- (ME/C) listed causes of death (CODs). COD diagnosis concordance decreased with NASR’s uncertainty in the SUDEP diagnosis: highest for Definite SUDEP (84%, n = 158), lower in Definite Plus (50%, n = 36), and lowest in Possible (0%, n = 18). Rates of psychiatric comorbidity, substance abuse, and toxicology findings for drugs of abuse were all higher in discordant cases than concordant cases. Possible SUDEP cases, an understudied group, were significantly older, and had higher rates of cardiac, drug, or toxicology findings than more certain SUDEP cases. With a potentially contributing or competing COD, ME/Cs favored non–epilepsy-related diagnoses, suggesting a bias toward listing CODs with structural or toxicological findings; SUDEP has no pathognomonic features. A history of epilepsy should always be listed on death certificates and autopsy reports. Even without an alternate COD, ME/Cs infrequently classified COD as “SUDEP.” Improved collaboration and communication between epilepsy and ME/C communities improve diagnostic accuracy, as well as bereavement and research opportunities.