Superoxide Radical-Mediated Self-Synthesized Au/MoO3-x Hybrids with Enhanced Peroxidase-like Activity and Photothermal Effect for Anti-MRSA Therapy.

A rapid increase in methicillin-resistant Staphylococcus aureus (MRSA) induced infection has been noticed in recent years and the biofilm formed by MRSA further delays wound healing, causing a high mortality rate. Hence, a safe and effective superoxide radical (O2•-) mediated self-synthesis strategy is developed to prepare Au-doped MoO3-x (Au/MoO3-x) plasmonic-semiconductor hybrid for the elimination of MRSA mediated wound infection. The synthesis mechanism of Au NPs is systematically investigated, proving that O2•- plays a key role in reduction of HAuCl4 into Au NPs in the presence of H2O and O2. Au-doped MoO3-x exhibits the improved photothermal conversion efficiency (∼52.40%) compared with MoO3-x (∼41.11%). Moreover, the peroxidase (POD)-like activity of Au/MoO3-x hybrid is higher than that of MoO3-x NPs, resulting in increased yield of highly toxic ·OH. In combination with the enhanced photothermal and POD-like properties, Au/MoO3-x hybrid achieves efficient elimination of MRSA bacteria with eradication ratio of ∼99.76%. Additionally, the as-prepared Au/MoO3-x NPs exhibit excellent biosafety, which is verified via in vitro and in vivo experiments. This study provides the basis for exploring MoO3-x-based hybrids via a green O2•--mediated self-synthesis approach.

Intracellular GSH/GST antioxidants system change as an earlier biomarker for toxicity evaluation of iron oxide nanoparticles.

Glutathione (GSH) and glutathione-S-transferases (GSTs) are two frontlines of cellular defense against both acute and chronic toxicity of xenobiotics-induced oxidative stress. The contribution of GSH and GST enzymes to signaling pathways and the regulation of GSH homeostasis play a central role in the detoxification of numerous environmental toxins and impurities. Iron oxide nanoparticles stemmed from traffic exhaust, steel manufacturing, or welding as a potential environmental pollution can lead to adverse respiratory outcomes and aggravate the risk of chronic health conditions via persistent oxidative stress. In this work, two kinds of acute exposure experiments of iron oxide (Fe2O3 and Fe3O4) nanoparticles in cells and in vivo were conducted to evaluate the GSH levels and GST activity. Our current research presented Fe3O4 nanoparticles at lower concentrations (≤100 µg/ml) seem to be more toxic to the human bronchial epithelial cells as their consumption of GSH and decrease of GST activity. The catalysis activity of Fe3O4 nanoparticles per se may contribute to the intracellular GSH consumption along with inhibition of glutathione-S-transferase class mu 1 and P (GSTM1 and GSTP1) active site and expression decrease of GSTM1 and GSTP1. Accordingly, the GSH consumption and decrease in GST activity directed to the further lipid peroxidation regarded as an earlier marker for toxicity evaluation of iron oxide nanoparticles, and relevant intervention may be effective for prevention of respiratory exposure induced damage from iron oxide nanoparticles.

Near-Infrared Regulated Nanozymatic/Photothermal/Photodynamic Triple-Therapy for Combating Multidrug-Resistant Bacterial Infections via Oxygen-Vacancy Molybdenum Trioxide Nanodots.

Bacterial infections have become a major danger to public health because of the appearance of the antibiotic resistance. The synergistic combination of multiple therapies should be more effective compared with the respective one alone, but has been rarely demonstrated in combating bacterial infections till now. Herein, oxygen-vacancy molybdenum trioxide nanodots (MoO3-x NDs) are proposed as an efficient and safe bacteriostatic. The MoO3-x NDs alone possess triple-therapy synergistic efficiency based on the single near-infrared irradiation (808 nm) regulated combination of photodynamic, photothermal, and peroxidase-like enzymatic activities. Therein, photodynamic and photothermal therapies can be both achieved under the excitation of a single wavelength light source (808 nm). Both the photodynamic and nanozyme activity can result in the generation of reactive oxygen species (ROS) to reach the broad-spectrum sterilization. Interestingly, the photothermal effect can regulate the MoO3-x NDs to their optimum enzymatic temperature (50 °C) to give sufficient ROS generation in low concentration of H2 O2 (100 µm). The MoO3-x NDs show excellent antibacterial efficiency against drug-resistance extended spectrum ß-lactamases producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Animal experiments further indicate that the MoO3-x NDs can effectively treat wounds infected with MRSA in living systems.

Aplysin Retards Pancreatic Necrosis and Inflammatory Responses in NOD Mice by Stabilizing Intestinal Barriers and Regulating Gut Microbial Composition.

Aplysin is a brominated sesquiterpene with an isoprene skeleton and has biological activities. The purpose of this study is to investigate the inhibitory effect of aplysin on spontaneous pancreatic necrosis in nonobese diabetic (NOD) mice and its potential mechanisms. Results showed that NOD mice at 12 weeks of age showed obvious spontaneous pancreatic necrosis, damaged tight junctions of intestinal epithelia, and widened gaps in tight and adherens junctions. Aplysin intervention was able to alleviate spontaneous pancreatic necrosis in NOD mice, accompanied with decreased serum endotoxin levels and downregulated expressions of Toll-like receptor 4 and its related molecules MyD88, TRAF-6, NF-κB p65, TRIF, TRAM, and IRF-3, as well as protein levels of interleukin-1ß and interferon-ß in pancreatic tissues. In addition, we observed obvious improvements of intestinal mucosal barrier function and changes of gut microbiota in the relative abundance at the phylum level and the genus level in aplysin-treated mice compared with control mice. Together, these data suggested that aplysin could retard spontaneous pancreatic necrosis and inflammatory responses in NOD mice through the stabilization of intestinal barriers and regulation of gut microbial composition.

High-content analysis of particulate matters-induced oxidative stress and organelle dysfunction in vitro.

Oxidative stress is usually considered to be a common mechanism by which particulate matter (PM) exposure induces adverse effects. However, the further biological events such as organelle dysfunction following oxidative stress remain to be explored. In this study, we applied high-content screening (HCS) technique to investigate the toxicological effects of carbon black (CB), diesel exhaust particle (DEP) and PM2.5 on oxidative stress and organelle function in human bronchial epithelial cell (16HBE), human embryo lung fibroblast cell (HELF) and human umbilical vein endothelial cell (HUVEC) which were used to represent distinct regions of the lung, and compared the toxicity impacts of different PMs and the sensitiveness of cell lines. We found three types of PMs induced mitochondrial dysfunction in three cell lines and lysosomal alkalinization in HUVEC while only CB triggered endoplasmic reticulum (ER) stress in 16HBE and HUVEC, and oxidative stress might mediate these processes. Moreover, CB basically exhibited more potent toxicity compared with DEP and PM2.5, which might be attributed to its less oxygen content. Finally, the finding that PMs-induced toxicity impacts exhibited a cell-type dependent manner might provide some information to help to understand the sensitivity of different tissue in the lung.

Tegillarca granosa extract Haishengsu inhibits tumor activity via a mitochondrial­mediated apoptotic pathway.

Haishengsu (HSS) is an active natural extract isolated from Tegillarca granosa, which has previously been demonstrated to inhibit the proliferation of several types of cancer cells in vitro. Our previous study indicated that HSS may induce apoptosis to suppress growth of human hepatocellular carcinoma BEL­7402 cells by activating Fas pathway. The present study demonstrated that HSS treatment induces the in vitro apoptosis of BEL­7402 cells via the mitochondrial­mediated apoptotic pathway detected by DNA fragmentation assay, caspase activity assay and transmission electron microscopy assay, and inhibits tumor xenograft growth in vivo. Alterations in apoptotic regulatory proteins were detected, including decreased expression of B­cell lymphoma2 (Bcl­2), upregulation of Bcl­2­associated X protein and mitochondrial cytochrome c release, and downstream activation of apoptotic signaling. Furthermore, apoptotic induction was caspase­dependent, as indicated by cleavage of the caspase substrate, poly (ADP­ribose) polymerase. Oral administration of 62.5­250 mg/kg HSS markedly educed the growth of hepatocellular carcinoma tumor xenografts in nude mice. In addition, immunohistochemical staining for caspase­3 protein and transmission electron microscopy further indicated the induction of apoptosis in these tumor tissues. Taken together, the present study demonstrated that HSS may effectively induce apoptosis to suppress the growth of BEL­7402 cells in vitro and in vivo, and therefore may hold promise for further development as a novel cancer therapy.

Antitumor effects of a polypeptide isolated from Tegillarca granosa linnaeus and the related molecular mechanism.

This study is to investigate the anticancer effects and mechanisms of Tegillarca granosa Linnaeus-1 (TG-1) on renal carcinoma OS-RC-2 cells in vitro. The proliferation of OS-RC-2 cells was evaluated under various concentrations of TG-1 using MTT assay. The apoptosis of OS-RC-2 cells was analyzed using acridine orange/ethidium bromide staining. And the cell cycle distribution of OS-RC-2 cells was detected by flow cytometry. In addition, the expression level of Ki67 mRNA was examined by RT-PCR and level of casepase-3 was examined by Western blot analysis. TG-1 incubation significantly inhibited the proliferation of renal carcinoma OS-RC-2 cells and arrested cells at G0/G1 phase (P <0.05). And TG-1 also significantly inhibited the expression of Ki67 mRNA (P<0.05). Additionally, TG-1 significantly promoted apoptosis and the expression of caspase-3 in cells (P<0.05). Moreover, the optimal effects of TG-1 was achieved at the concentration of 100 mg/L The results indicate that TG-1 has antitumor effects on renal carcinoma OS-RC-2 cells and that the underlying mechanisms may be acted through inhibiting proliferation and Ki67 mRNA expression, and promoting apoptosis and caspase-3 expression.

[Observation on the ultrastructure of Pneumocystis carinii].

OBJECTIVE: To study the life cycle and morphology of Pneumocystis carinii by ultrastructural observation. METHODS: Wistar rat model of P. carinii infection was established by subcutaneous injection with dexamethasone. Lung tissue of the infected rats was used for the transmission electron microscopical study. RESULTS: The organisms were mainly present in the lung alveolar cavity, and also in the alveolar septum, pulmonary macrophages and neutrophils. More trophozoites of P. carinii attached to the type I alveolar epithelial cells, and rarely to the type II alveolar epithelial cells. Most of these trophozoites showed pseudopodial evaginations on their pellicles. The nucleus-associated organelle and spindle microtubules were observed in some trophozoites. The precyst phase was in three forms: early, intermediate and late form. Synaptonemal complexes indicating meiotic nuclear divisions and a clump of mitochondria were also observed in the precyst. The pellicle of the cyst has a thickened portion with a pore. There were nucleus with nucleolus, mitochondrion, vesicles, endoplasmic reticulum and numerous ribosomes in the organisms, and tubular expansions on its surface. CONCLUSION: The life cycle of P. carinii consists of trophozoite, precyst and cyst stages. The presence of a single pore in the cyst wall reveals that pore formation may be a mode of excystation for intracystic bodies of P. carinii.