Increased inflammatory mediators levels are associated with clinical outcomes and prolonged illness in severe COVID-19 patients.

OBJECTIVE: The purpose of this study was to identify potential predictors of clinical outcome in severe COVID-19 patients and to investigate the relationship between immunological parameters and duration of illness. METHODS: This single-center study retrospectively recruited 73 patients with severe or critical COVID-19. Immunological indicators include white blood cell count, neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio, and circulating inflammatory mediators were observed for their association with disease severity, mortality and duration of illness of COVID-19. RESULTS: Serum inflammatory mediators levels of C-reactive protein (P = 0.015), interleukin 6 (IL-6) (P < 0.001), CX3CL1 (P < 0.001), D-dimer (P < 0.001) and procalcitonin (PCT) (P < 0.001) were increased in critical illness patients compared to those severe COVID-19 patients. CX3CL1 has the highest C-index (0.75) to predict in-hospital mortality in patients with COVID-19. Furthermore, this study shows for the first time that the duration of illness in severe COVID-19 patients is associated with serum levels of CX3CL1 (P = 0.037) and D-dimer (P = 0.014). CONCLUSION: CX3CL1, D-dimer, PCT, and IL-6 could effectively predict mortality in severe COVID-19 patients. In addition, only the circulating levels of CX3CL1 and D-dimer were significantly associated with duration of illness.

Phase behavior, rheological property, and transmutation of vesicles in fluorocarbon and hydrocarbon surfactant mixtures.

We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(α) two-phase region, and a single L(α) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(α) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(α) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by (19)F NMR as well as (31)P NMR measurements. Upon replacement of NFDA by DEHPA, the signal from the (19)F atoms adjacent to the hydrophilic headgroup disappears and that from the (19)F atoms on the main chain becomes sharper. This could be interpreted as an increase of microfluidity in the mixed vesicle bilayers at higher content of DEHPA, whose alkyl chains are expected to have a lower chain melting point. Our results provide basic knowledge on vesicle formation and their structural evolution in salt-free catanionic surfactant systems containing mixed ion pairs, which may contribute to a deeper understanding of the rules governing the formation and properties of surfactant self-assembly.