Discovery of thiazole salt AChE inhibitors and development of thiamine disulfide prodrugs targeting the central nervous system.

The selective AChE inhibitor donepezil has been approved by the FDA as a first-line drug for the treatment of mild to moderate AD. However, many peripheral side effects were observed in patients taking donepezil. Our main objective here is to provide insight into the opportunities and challenges associated with development of AChE inhibitors with high brain exposure and low peripheral side effects. In this study, we have for the first time revealed a series of novel thiazole salt AChE inhibitors, which exhibit a nanomolar inhibitory effect on human AChE. We further developed thiamine disulfide prodrugs based on optimized thiazole salt AChE inhibitors, which are reduced in the brain to form thiazole salt AChE inhibitors. In vivo experiments have confirmed that the representative prodrug Tap4 (i.p., 10 mg/kg) can be converted into the thiazole salt AChE inhibitor Tat2 and shows high brain exposure, reaching 500 ng/g. Further, the inhibitory effect of the prodrug Tap4 on AChE is obviously stronger in the brain than that on intestinal AChE of ICR mice. Our study provides a possible basis for centrally targeted thiazole salt inhibitors in the treatment of neurodegenerative diseases.

Effectiveness and Safety of Baidu Jieduan Granules for COVID-19: A Retrospective Observational Multicenter Study.

OBJECTIVE: To evaluate the effectiveness and safety of Baidu Jieduan Granules (BDJDG) to treat common type coronavirus disease 2019 (COVID-19). METHODS: This multicenter, retrospective, and observational clinical trial included 230 common COVID-19 patients in Leishenshan, Huangshi, and Laohekou Hospitals in Wuhan from January 21 to March 26, 2020. The included patients were further divided into two subgroups according to the use of supplemental oxygen, mild and moderate groups. During the first 14 d of hospitalization, all patients were administered BDJDG combined with conventional Western medicine, and observed for continuous 28 d. Primary outcomes were disease progression rate and discharge rate. Secondary outcomes included negative conversion time of nucleic acid, hospitalization duration, clinical symptom subsidence time, and symptom regression rate. RESULTS: A total of 230 common COVID-19 patients were analyzed (138 in moderate group and 92 in mild group). By day 28, the disease progression rate was 4.3% and the discharge rate was 95.7%. All mild cases recovered and were discharged from hospital. The median negative conversion time of nucleic acid of all 230 COVID-19 patients was 12 d [inter-quartile range (IQR) 3.5-17], the median hospitalization duration was 15 d (IQR 12-20). The median time to fever, cough, and fatigue recovery was 4 d (IQR 2-6), 8 d (IQR 5-12), and 8 d (IQR 5-11). The recovery rate of fever, cough, and fatigue was 94.6%, 90.5%, and 93.5%. The median time to clinical improvement was 12 d (IQR 10-17). Compared with the baseline, total leukocyte counts, neutrophil counts, lymphocyte counts, and platelet counts were increased significantly on days 7 and 14 (P<0.01). C-reactive protein markedly increased on day 3 and significantly decreased on days 7 and 14 (P<0.01). No serious adverse events occurred during treatment. CONCLUSION: BDJDG may be effective and safe for treatment of common type COVID-19. (Registration No. ChiCTR2000030836).

Kinetics of coupling water and cryoprotectant transport across cell membranes and applications to cryopreservation.

Thermodynamic and kinetic models can provide a wealth of information on the physical response of living cells and tissues experiencing cryopreservation procedures. Both isothermal and nonisothermal models have been proposed so far, accompanied by experimental verification and cryoapplications. But the cryoprotective solution is usually assumed to be dilute and ideal in the models proposed in the literature. Additionally, few nonisothermal models are able to couple the transmembrane transport of water and cryoprotectant during cooling and warming of cells. To overcome these limitations, this study develops a whole new set of equations that can quantify the cotransport of water and cryoprotectant across cell membranes in the nondilute and nonideal solution during the freezing and thawing protocols. The new models proposed here can be simplified into ones consistent with the classic models if some specific assumptions are included. For cryobiological practice, they are applied to predict the volumetric change for imprinting control region (ICR) mouse spermatozoa and human corneal keratocytes in the freezing protocol. The new models can determine the intracellular concentration of cryoprotectant more precisely than others by abandoning the assumptions such as dilute and ideal solutions and nonpermeability of membranes to cryoprotectant. Further, the findings in this study will offer new insights into the physical response of cells undergoing cryopreservation.

Molecular dynamics study of effects of temperature and concentration on hydrogen-bond abilities of ethylene glycol and glycerol: implications for cryopreservation.

The state of intracellular water is important in all phases of cryopreservation. Intracellular water can be transported out of the cell, transferred into its solid phase, or blocked by cryoprotectants and proteins in the cytoplasm. The purpose of the present study is to determine the amount of hydrogen-bonded water in aqueous ethylene glycol and glycerol solutions. The effects of temperature and concentration on the density and the hydrogen bonding characteristics of the solution are evaluated quantitatively in this study. To achieve these aims, a series of molecular dynamics simulations of ethylene glycol/water and glycerol/water mixtures of molalities ranging from 1 to 5 m are conducted at 1 atm and at 273, 285, and 298 K, respectively. The simulation results show that temperature and concentration have variable effects on solution density. The proportion of the hydrogen-bonded water by solute molecules increases with rising molality. The ability of the solute molecules to hydrogen bond with water molecules weakens as the solution becomes more concentrated. Moreover, it turns out that the solution concentration can influence the hydrogen bonding characteristics more greatly than the temperature. The glycerol molecule should be a stronger "water blocker" than the ethylene glycol molecule corresponding to the same conditions. These findings provide insight into the cryoprotective mechanisms of ethylene glycol and glycerol in aqueous solutions, which will confer benefits on the cryopreservation.

Two applications of the thermogram of the alcohol/water binary system with compositions of cryobiological interests.

Quantitative analyses of the bound water content in the alcohol aqueous solution and its osmotic behavior should be cryobiologically significant. This paper has presented two applications of the thermogram of the alcohol/water system recorded by differential scanning calorimeter (DSC). Both applications are: (1) generating the quantitative relationship between the bound water content and the solution composition; (2) calculating the osmotic virial coefficients for alcohols. Five alcohols including methanol, ethanol, ethylene glycol, propylene glycol and glycerol are investigated. In the present study, partial binary phase diagrams of these five alcohol solutions are determined in the first place. The bound water contents in these solutions are quantitatively evaluated by three criteria afterwards. In the end, the osmotic virial coefficients for these alcohols are calculated according to the osmotic virial equation. It is turned out that the bound water fraction out of the total water content increases with a rising molality. The ability of the solute to restrict water molecules can be weakened when the solution becomes more concentrated. The results also indicate that propylene glycol should be the strongest "water-blocker" while methanol the weakest one. These findings can deepen our understanding of the cryoprotective properties of the alcohols from the perspectives of their roles in binding free water and promoting the osmotic efflux of cell water.

Kinetics of osmotic water flow across cell membranes in non-ideal solutions during freezing and thawing.

Cryopreservation requires quantitatively analytical models to simulate the biophysical responses of biomaterials during cryopreservation. The Mazur model and other improved ones, such as Karlsson model concerning solutions containing cryoprotectants (CPA), are somehow precluded by some minor points, particularly, the assumption of ideal solutions. To avoid the ideal solution assumption, in this study a new method is developed to simulate water transport across cell membranes in non-ideal solutions during cooling and thawing. The comparison between osmolalities calculated by the linear freezing-point depression used in this new method and other non-ideal ones is conducted and a good agreement is achieved. In addition, in an ideal case, besides a theoretical agreement, this new approach has been validated by its numerical simulation results. Comparisons between this new approach and the traditional ones with an ideal solution assumption have been conducted based on a spherical hypothetical cell. The main results are (1) the predicted non-ideal intracellular water content is larger than the ideal results; (2) the concentration of CPA solutions is directly proportional to the deviation between the non-ideal and ideal curves. In the end, this study presents a direct description of the degree of subcooling of the protoplasm during dynamic cooling. This study demonstrates that our experimental data-based method is a valid one with clear physical interpretations, convenient expressions and a more extensive application room than traditional ones.

Thermal analysis of tertiary butyl alcohol/sucrose/water ternary system.

The purpose of this work is to investigate the freezing properties of tertiary butyl alcohol (TBA)/sucrose/water ternary system. Differential scanning calorimetry (DSC) is employed to determine the glass transition temperature of the maximally freeze-concentrated solution Tg' and the crystallization (or devitrification) temperature Tr. DSC measurements show that the presence of sucrose hinders the crystallization of TBA during cooling. The residual TBA in the glassy state will cause a decrease in Tg' and will crystallize during heating. An increase in the cooling rate causes a decrease in Tg'. For 10% TBA/10% sucrose/water ternary system, the critical heating rate is approximately 250 degrees C/min. Annealing treatment at temperatures below Tg' causes the crystallization of TBA, which indicates that TBA molecules still have appreciable mobility even at temperatures below Tg'. When the ratio of TBA to sucrose is less than 0.2, TBA cannot crystallize during cooling.