COVID-19 severity in relation to sociodemographics and vitamin D use.

Most COVID-19 cases are treated as outpatients, while the majority of studies on COVID-19 focus on inpatients. Little is known about the self-reporting and self-rating of the disease's symptoms, and the associations of prophylactic use of dietary supplements with COVID-19 severity have not been addressed. The aims of this study are to evaluate COVID-19 severity and to relate them to sociodemographic characteristics and prophylactic dietary supplements. An observational patient-based study conducted through an online questionnaire on recovered COVID-19 patients. The patients were assessed for several severity parameters, sociodemographic parameters, and prophylactic dietary supplement use. A total of 428 patients were evaluated. Age and presence of comorbidities had positive associations with the severity parameters. The severe infection group had the highest proportion of patients stressed about COVID-19 (P < 0.05). Cigarette, but not hookah, smoking was significantly associated with less severe symptoms. Vitamin D negatively predicted disease severity (P < 0.05). In conclusion, stress, age, and presence of comorbidities were the most important positive predictors of COVID-19 severity, while prophylactic vitamin D use and smoking were significant negative predictors. The use of protective measures and other prophylactic dietary supplements was not significantly associated with symptom severity.

Fluorescence Approaches to Image and Quantify the Demarcation Membrane System in Living Megakaryocytes.

The demarcation membrane system (DMS) develops to provide additional surface membrane for the process of platelet production. The DMS is an invagination of the plasma membrane that can extend throughout the extranuclear volume of mature megakaryocytes and its lumen is continuous with the extracellular solution. DMS ultrastructure in fixed samples has been extensively studied using transmission electron microscopy (TEM) and more recently with focused ion beam scanning EM. In addition, whole cell patch clamp membrane capacitance provides a direct measurement of DMS content in living megakaryocytes. However, fluorescence methods to image and quantify the DMS in living megakaryocytes provide several advantages. For example, confocal fluorescence microscopy is easier to use compared to EM or electrophysiological methods and the required equipment is more readily available. In addition, use of living cells avoids artifacts known to occur during the fixation, dehydration, or embedding steps used to prepare EM samples. Here we describe the use of styryl dyes such as FM 1-43 or di-8-ANEPPS and impermeant fluorescent indicators of the extracellular space as simple approaches for imaging and quantification of the DMS.

Detachment of surface membrane invagination systems by cationic amphiphilic drugs.

Several cell types develop extensive plasma membrane invaginations to serve a specific physiological function. For example, the megakaryocyte demarcation membrane system (DMS) provides a membrane reserve for platelet production and muscle transverse (T) tubules facilitate excitation:contraction coupling. Using impermeant fluorescent indicators, capacitance measurements and electron microscopy, we show that multiple cationic amphiphilic drugs (CADs) cause complete separation of the DMS from the surface membrane in rat megakaryocytes. This includes the calmodulin inhibitor W-7, the phospholipase-C inhibitor U73122, and anti-psychotic phenothiazines. CADs also caused loss of T tubules in rat cardiac ventricular myocytes and the open canalicular system of human platelets. Anionic amphiphiles, U73343 (a less electrophilic U73122 analogue) and a range of kinase inhibitors were without effect on the DMS. CADs are known to accumulate in the inner leaflet of the cell membrane where they bind to anionic lipids, especially PI(4,5)P2. We therefore propose that surface detachment of membrane invaginations results from an ability of CADs to interfere with PI(4,5)P2 interactions with cytoskeletal or BAR domain proteins. This establishes a detubulating action of a large class of pharmaceutical compounds.