Accurate Determination of the Degree of Deacetylation of Chitosan Using UPLC-MS/MS.

The mole fraction of deacetylated monomeric units in chitosan (CS) molecules is referred to as CS's degree of deacetylation (DD). In this study, 35 characteristic ions of CS were detected using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). The relative response intensity of 35 characteristic ion pairs using a single charge in nine CS samples with varying DDs was analyzed using 30 analytical methods. There was a good linear relationship between the relative response intensity of the characteristic ion pairs determined using ultrahigh performance (UP) LC-MS/MS and the DD of CS. The UPLC-MS/MS method for determining the DD of CS was unaffected by the sample concentration. The detection instrument has a wide range of application parameters with different voltages, high temperatures, and gas flow conditions. This study established a detection method for the DD of CS with high sensitivity, fast analysis, accuracy, stability, and durability.

Bioavailability Enhancement of Cepharanthine via Pulmonary Administration in Rats and Its Therapeutic Potential for Pulmonary Fibrosis Associated with COVID-19 Infection.

Cepharanthine (CEP) has excellent anti-SARS-CoV-2 properties, indicating its favorable potential for COVID-19 treatment. However, its application is challenged by its poor dissolubility and oral bioavailability. The present study aimed to improve the bioavailability of CEP by optimizing its solubility and through a pulmonary delivery method, which improved its bioavailability by five times when compared to that through the oral delivery method (68.07% vs. 13.15%). An ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS) method for quantification of CEP in rat plasma was developed and validated to support the bioavailability and pharmacokinetic studies. In addition, pulmonary fibrosis was recognized as a sequela of COVID-19 infection, warranting further evaluation of the therapeutic potential of CEP on a rat lung fibrosis model. The antifibrotic effect was assessed by analysis of lung index and histopathological examination, detection of transforming growth factor (TGF)-ß1, interleukin-6 (IL-6), α-smooth muscle actin (α-SMA), and hydroxyproline level in serum or lung tissues. Our data demonstrated that CEP could significantly alleviate bleomycin (BLM)-induced collagen accumulation and inflammation, thereby exerting protective effects against pulmonary fibrosis. Our results provide evidence supporting the hypothesis that pulmonary delivery CEP may be a promising therapy for pulmonary fibrosis associated with COVID-19 infection.

A novel method to quantify chitosan in aqueous solutions by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

In this study, a novel and accurate quantitative analysis method for the direct determination of chitosan (CS) in aqueous solutions using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is presented. By detecting the mass spectrum response intensity of a series of CS characteristic ion pairs, the sample concentration (abscissa) was linearly fitted with the total ion current (TIC) response intensity of its characteristic ion pairs (ordinate). A reliable standard curve was derived for quantifying CS in the range of 125-4000 ng/mL. Under the detection conditions, this CS quantification method yielded acceptable specificity (no interference peak), linearity (with correlation coefficient (r2) values >0.999), precision (acceptable limit RSDr < 3 %, RSDR < 6 %), accuracy (RE within the acceptable limits of ±5 %), and stability (acceptable limit RE within ±5 %, RSDr < 3 %). Moreover, the applicability of measurement was verified when a series of substrates did not interact with CS in the solution. Results have verified the applicability of this method for determining CS content in different composites. This study provides a method for determining CS content with significant practical value and economic benefit.

Blocking TRAIL-DR5 signaling pathway with soluble death receptor 5 fusion protein mitigates radiation-induced injury.

The increasing application of nuclear technology, the high fatality of acute radiation syndrome (ARS) and its complex mechanism make ARS a global difficulty that requires urgent attention. Here we reported that the death receptor 5 (DR5), as well as its ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), were both significantly upregulated after irradiation in mice with 6 Gy γ-ray single radiation. And by intravenously administrated with soluble DR5 fusion protein (sDR5-Fc), the competitive antagonist of DR5, the excessive apoptosis in the radiation-sensitive tissues such as spleen and thymus were significantly inhibited and the radiation-induced damage of spleen and thymus were mitigated, while the expression of apoptosis-inhibiting proteins such as Bcl-2 was also significantly upregulated. The biochemical indicators such as serum ALP, AST, ALT, TBIL, K, and Cl levels that affected by radiation, were improved by sDR5-Fc administration. sDR5-Fc can also regulate the number of immune cells and reduce blood cell death. For in vitro studies, it had been found that sDR5-Fc effectively inhibited apoptosis of human small intestinal mucosal epithelial cells and IEC-6 cells using flow cytometry. Finally, survival studies showed that mice administrated with sDR5-Fc after 9 Gy γ-ray single whole body radiation effectively increased the 30-day survival and was in a significant dose-dependent manner. Overall, the findings revealed that DR5/TRAIL-mediated apoptosis pathway had played important roles in the injury of ARS mice, and DR5 probably be a potential target for ARS therapeutics. And the DR5 apoptosis antagonist, sDR5 fusion protein, probably is a promising anti-ARS drug candidate which deserves further investigation.

Single-Atom Pt+ Derived from the Laser Dissociation of a Platinum Cluster: Insights into Nonoxidative Alkane Conversion.

In this study, we construct a 193 nm ultraviolet laser dissociation high-resolution mass spectrometry (HRMS) platform to produce Pt+ cations with high efficiency, which is in situ applied for monitoring the "Pt+ + alkanes" reactions (where alkanes include methane, ethane, and propane). The conversion intermediates and products could be accurately determined by an orbitrap detector with high resolution (up to 150 000). Importantly, methane conversion by Pt+ cations yields [Pt + ethane]+ and [Pt + ethylene]+ as the sole products formed via the cross-coupling reaction of the Pt-CH2 intermediate with gaseous methane. However, the Pt+ cations promote only the nonoxidative dehydrogenation of ethane and propane to give the corresponding [Pt + alkenes]+ and [Pt + alkynes]+. The details of the reaction mechanism are corroborated by density functional theory (DFT) calculations. These results highlight the power of HRMS with the laser dissociation of metal clusters in the generation and reaction characterization of metal ions.

Development of a novel DNA sequencing method not only for hepatitis B virus genotyping but also for drug resistant mutation detection.

BACKGROUND: In HBV-infected patients, different genotypes of the hepatitis B virus influence liver disease progression and response to antiviral therapy. Moreover, long-term antiviral therapy will eventually select for drug-resistant mutants. Detection of mutations associated to antiviral therapy and HBV genotyping are essential for monitoring treatment of chronic hepatitis B patients. RESULTS: In this study, a simple method of partial-S gene sequencing using a common PCR amplification was established for genotyping clinical HBV isolates sensitively, which could detect the drug-resistant mutations successfully at the same time. CONCLUSIONS: The partial S gene sequencing assay developed in this study has potential for application in HBV genotyping and drug resistant mutation detection. It is simpler and more convenient than traditional S gene sequencing, but has nearly the same sensitivity and specificity when compared to S gene sequencing.

[Effects of Astragalus Membranaceus Injection on TNF-alpha-induced release of inflammatory factors from HUVECs and the molecular mechanisms].

OBJECTIVE: To investigate the protective effect of Astragalus Membranaceus Injection on human umbilical vein endothelial cells (HUVECs) against tumor necrosis factor alpha (TNF-alpha). METHODS: Cultured passage 2 HUVECs were stimulated with TNF-alpha with or without a 2-h Astragalus Membranaceus Injection treatment. The expression of nuclear factor-kappaB (NF-kappaB) subunit p65 were evaluated by immuncytochemistical method, and the levels of p65 in the nuclei and the protein Ikappabetaalpha in the cytoplasm were evaluated by Western blotting. The levels of interleukin-6 (IL-6) and soluble intracellular adhesion molecule-1 (sICAM-1) in the cell culture were determined with ELISA. RESULTS: TNF-alpha induced the activation of NF-kappaB and increased the expressions of IL-6 and sICAM-1 in HUVECs. The activation of NF-kappabeta by TNF-alpha was suppressed by Astragalus Membranaceus Injection in a dose-dependent manner. CONCLUSION: Astragalus Membranaceus Injection can inhibit the TNF-alpha-induced expression of IL-6 and sICAM-1 by suppressing NF-kappabeta activation, suggesting its protective effect on the endothelial function.