Mechanisms of lipid extraction from skin lipid bilayers by sebum triglycerides

The skin surface, our first barrier against the external environment, is covered by the sebum oil, a lipid film composed of sebaceous and epidermal lipids, which is important in the regulation of the hydration level of our skin. Here, we investigate the pathways leading to the transfer of epidermal lipids from the skin lipid bilayer to the sebum. We show that the sebum triglycerides, a major component of sebum, interact strongly with the epidermal lipids and extract them from the bilayer. Using microsecond time scale molecular dynamics simulations, we identify and quantify the free energy associated with the skin lipid extraction process

Thermal transport across nanoparticle-fluid interfaces: the interplay of interfacial curvature and nanoparticle-fluid interactions

We investigate the general dependence of the thermal transport across nanoparticle–fluid interfaces using molecular dynamics computations. We show that the thermal conductance depends strongly both on the wetting characteristics of the nanoparticle–fluid interface and on the nanoparticle size. Strong nanoparticle–fluid interactions, leading to full wetting states in the host fluid, result in high thermal conductances and efficient interfacial transport of heat. Weak interactions result in partial drying or full drying states, and low thermal conductances. The variation of the thermal conductance with particle size is found to depend on the fluid–nanoparticle interactions. Strong interactions coupled with large interfacial curvatures lead to optimum interfacial heat transport. This complex dependence can be modelled using an equation that includes the interfacial curvature as a parameter. In this way, we rationalise the existing experimental and computer simulation results and show that the thermal transport across nanoscale interfaces is determined by the correlations of both interfacial curvature and nanoparticle–fluid interactions

COVID-19 infection in adult patients with hematological malignancies: a European Hematology Association Survey (EPICOVIDEHA)

Background: Patients with hematological malignancies (HM) are at high risk of mortality from SARS-CoV-2 disease 2019 (COVID-19). A better understanding of risk factors for adverse outcomes may improve clinical management in these patients. We therefore studied baseline characteristics of HM patients developing COVID-19 and analyzed predictors of mortality. Methods: The survey was supported by the Scientific Working Group Infection in Hematology of the European Hematology Association (EHA). Eligible for the analysis were adult patients with HM and laboratory-confirmed COVID-19 observed between March and December 2020. Results: The study sample includes 3801 cases, represented by lymphoproliferative (mainly non-Hodgkin lymphoma n = 1084, myeloma n = 684 and chronic lymphoid leukemia n = 474) and myeloproliferative malignancies (mainly acute myeloid leukemia n = 497 and myelodysplastic syndromes n = 279). Severe/critical COVID-19 was observed in 63.8% of patients (n = 2425). Overall, 2778 (73.1%) of the patients were hospitalized, 689 (18.1%) of whom were admitted to intensive care units (ICUs). Overall, 1185 patients (31.2%) died. The primary cause of death was COVID-19 in 688 patients (58.1%), HM in 173 patients (14.6%), and a combination of both COVID-19 and progressing HM in 155 patients (13.1%). Highest mortality was observed in acute myeloid leukemia (199/497, 40%) and myelodysplastic syndromes (118/279, 42.3%). The mortality rate significantly decreased between the first COVID-19 wave (March–May 2020) and the second wave (October–December 2020) (581/1427, 40.7% vs. 439/1773, 24.8%, p value < 0.0001). In the multivariable analysis, age, active malignancy, chronic cardiac disease, liver disease, renal impairment, smoking history, and ICU stay correlated with mortality. Acute myeloid leukemia was a higher mortality risk than lymphoproliferative diseases. Conclusions: This survey confirms that COVID-19 patients with HM are at high risk of lethal complications. However, improved COVID-19 prevention has reduced mortality despite an increase in the number of reported cases.EPICOVIDEHA has received funds from Optics COMMITTM (COVID-19 Unmet Medical Needs and Associated Research Extension) COVID-19 RFP program by GILEAD Science, United States (Project 2020-8223)

Understanding the interactions between sebum triglycerides and water: a molecular dynamics simulation study.

In recent years, sebum oil has been found to play a key role in the regulation of the hydration of the outermost layer of the skin, the stratum corneum. Understanding how a major component of the sebum oil, the triglyceride tri-cis-6-hexadecenoin (TG), interacts with water is an important step in gaining insight into the water regulation function of the sebum oil. Here we use molecular dynamics simulations to investigate the structural and interfacial properties of TG in bulk and at the air and water interface. Our model performs very well in reproducing experimental results, such as density, surface tensions and surface pressure area isotherms. We show that triglyceride molecules in the liquid phase assemble together, through the glycerol group, forming a single percolating network. TG-air interfaces orient the lipids with the interface enriched with the hydrophobic tails and the glycerol groups buried inside. When in contact with water, the TG molecules at the interface orient the glycerol group towards the water phase and adopt a characteristic trident conformation. Water is shown to penetrate the TG layer thanks to the interaction with the oxygen atoms of the TG molecules, which acts as a pathway for water diffusion. The activation energy for the passage of water is found to be ≈9.5kBT at 310 K, showing that the layer is permeable to water diffusion

Micafungin for Candida Albicans Pacemaker-Associated Endocarditis: A Case Report and Review of the Literature

We report on the treatment with micafungin of a pacemaker-associated endocarditis due to Candida albicans. Antifungal therapy was able to reduce vegetation size from 5 to 1 cm making possible the transvenous removal of the device without a high risk of pulmonary embolism. Noteworthy, a high micafungin concentration was documented into the lead vegetation (10 mu g/g of vegetation tissue) and this may have contributed to the striking size reduction of vegetation