Survival of SARS-CoV-2 in artificial seawater and on the surface of inanimate materials.

There is a potential risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread through human contact with seafood and the inanimate materials contaminated by the virus. In this study, we examined the stability of the virus in artificial seawater (ASW) and on the surface of selected materials. SARS-CoV-2 (3.75 log10 TCID50 ) in ASW at 22℃ maintained infectious about 3 days and at 4℃ the virus survived more than 7 days. It should be noticed that viable virus at high titer (5.50 log10 TCID50 ) may survive more than 20 days in ASW at 4℃ and for 7 days at 22℃. SARS-CoV-2 on stainless steel and plastic bag maintained infectious for 3 days, and on nonwoven fabric for 1 day at 22℃. In addition, the virus remained infectious for 9 days on stainless steel and non-woven fabric, and on plastic bag for 12 days at 4℃. It is important to highlight the role of inanimate material surfaces as a source of infection and the necessity for surface decontamination and disinfection.

Mechano-Informed Biomimetic Polymer Scaffolds by Incorporating Self-Powered Zinc Oxide Nanogenerators Enhance Motor Recovery and Neural Function.

Piezoelectric materials can produce electrical power from the mechanical stimulation and thus, they may accelerate electroactive tissue healing as a promising treatment for traumatic peripheral nerve injuries. In this study, a piezoelectric zinc oxide nanogenerator scaffold is manufactured by 3D injectable multilayer biofabrication. The piezoelectric polymeric scaffold displays desirable mechanical and physical characteristics, such as aligned porosity, high elasticity, scaffold stiffness, surface energy, and excellent shear behavior. In addition, its biocompatibility supplies Schwann cells with an adhesive, proliferative, and angiogenic interface, as is reflected by higher expression of functional proteins including nerve growth factor (NGF) and vascular endothelial growth factor (VEGF). In vivo mechanical stimuli by treadmill practice contribute to the comprehensive reparative therapy. The piezoelectric conduit accelerates nerve conducting velocity, promotes axonal remyelination, and restores motor function by recovering endplate muscles. Moreover, the piezoelectric nanogenerator scaffold creates biomimetic electrically conductive microenvironment without causing noticeable toxicity to functioning organs and improves peripheral nerve restoration by the multifunctional characteristics. Therefore, the mechano-informed biomimetic piezoelectric scaffold may have enormous potential in the neuroengineering for regenerative medicine.

3D melatonin nerve scaffold reduces oxidative stress and inflammation and increases autophagy in peripheral nerve regeneration.

Peripheral nerve defect is a common and severe kind of injury in traumatic accidents. Melatonin can improve peripheral nerve recovery by inhibiting oxidative stress and inflammation after traumatic insults. In addition, it triggers autophagy pathways to increase regenerated nerve proliferation and to reduce apoptosis. In this study, we fabricated a melatonin-controlled-release scaffold to cure long-range nerve defects for the first time. 3D manufacture of melatonin/polycaprolactone nerve guide conduit increased Schwann cell proliferation and neural expression in vitro and promoted functional, electrophysiological and morphological nerve regeneration in vivo. Melatonin nerve guide conduit ameliorated immune milieu by reducing oxidative stress, inflammation and mitochondrial dysfunction. In addition, it activated autophagy to restore ideal microenvironment, to provide energy for nerves and to reduce nerve cell apoptosis, thus facilitating nerve debris clearance and neural proliferation. This innovative scaffold will have huge significance in the nerve engineering.

The aflatoxin-detoxifizyme specific expression in mouse parotid gland.

The aflatoxin-detoxifizyme (ADTZ) gene derived from Armillariella tabescens was cloned into parotid gland-specific expression vector (pPSPBGPneo) to construct the parotid gland-specific vector expressing ADTZ (pPSPBGPneo-ADTZ). Transgenic mice were generated by microinjection and identified by using PCR and Southern blotting analysis. PCR and Southern blotting analysis showed that total six transgenic mice carried the ADTZ gene were generated. RT-PCR analysis indicated that the expression of ADTZ mRNA could be detected only in parotid glands of the transgenic mice. The ADTZ activity in the saliva was found to be 3.72 ± 1.64 U/mL. After feeding a diet containing aflatoxin B1 (AFB1) for 14 days, the effect of ADTZ on serum biochemical indexes and AFB1 residues in serum and liver of mice were evaluated. The results showed that total protein and globulin contents in the test treatment (transgenic mice) produced ADTZ were significantly higher than that of the positive control, while alanine aminotransferase and aspartate aminotransferase activity in serum of the test treatment (transgenic mice) were remarkably lower compared to that of the positive control (P < 0.05). Moreover, AFB1 residues in serum and liver of the test treatment (transgenic mice) were significantly lower compared with that of the positive control (P < 0.05). These results in the study confirmed that ADTZ produced in transgenic mice could reduce, even eliminate the negative effects of AFB1 on mice.

Special Distribution of Nanoplastics in the Central Nervous System of Zebrafish during Early Development.

There is growing concern about the distribution of nanoplastics (NPs) in the central nervous system (CNS), whereas intrusion is poorly understood. In this study, fluorescent-labeled polystyrene NPs (PS-NPs) were microinjected into different areas of zebrafish embryo to mimic different routes of exposure. PS-NPs were observed in the brain, eyes, and spinal cord through gametal exposure. It indicated that maternally derived PS-NPs were specially distributed in the CNS of zebrafish during early development. Importantly, these NPs were stranded in the CNS but not transferred to other organs during development. Furthermore, using neuron GFP-labeled transgenic zebrafish, colocalization between NPs and the neuron cells revealed that NPs were mostly enriched in the CNS surrounded but not the neurons. Even so, the intrusion of NPs into the CNS induced the significant upregulation of some neurotransmitter receptors, leading to an inhibited effect on the movement of zebrafish larvae. This work provides insights into understanding the intrusion and distribution of NPs in the CNS and the subsequent potential adverse effects.

[Serial reconstruction strategy for severe cervical cicatrix deformity].

OBJECTIVE: To explore serial reconstruction strategy for severe cervical cicatrix deformity. METHODS: A total of 24 cases, III or IV degree cervical contracture deformity, were treated in Shanghai Ninth People's Hospital from January 2006 to December 2011. There were 18 males and 6 females with an average age of 35.4 years. The etiologies included burns, chemical injuries and scalding. Three evaluation indices of mental cervical angle (MCA) including soft tissue MCA, osseous MCA and dynamic MCA were measured before treatment and during follow-ups. The first-stage treatment was comprised of cervical cicatrix resection, contracture release, lift of dual direction platysma flap, reconstruction of MCA and skin grafting. At Months 3-6, second-stage treatment was performed, including lower mandible scar resection, correction of lower lip eversion, lower mandible region reconstruction with free (para-) scapular skin flap. After two-stage treatment, the patients underwent periodical re-evaluations for gross appearance, function and measurement of MCA. RESULTS: Twenty-two patients completing two-stage reconstruction were followed up. Notable improvement of cervical mobilization and contour were achieved. Soft tissue MCA decreased from 130° ± 34° to 110° ± 24°, osseous MCA increased from 71° ± 23° to 95° ± 19° and dynamic MCA increased from 25° ± 18° to 80° ± 26°. CONCLUSIONS: The serial treatment strategy is effective. In comparisons with reconstruction with skin graft only or skin flap only, the strategy possesses many advantages.

Nitric Oxide-Releasing Silicone Oil with Tunable Payload for Antibacterial Applications.

Bacterial infections are a hurdle to the application of medical devices, and in the United States alone, more than one million infection cases are reported annually from indwelling medical devices. Infections not only affect the function of medical devices but also risk the lives and health of patients. Nitric oxide (NO) has been used as an antibacterial therapy that kills bacteria without causing resistance and provides many therapeutic effects such as anti-inflammation, antithrombosis, and angiogenesis. Silicone oils have been widely utilized in manufacturing consumer goods, healthcare products, and medical products. Specifically, liquid silicone oils are used as a medical lubricant that creates lubricated interfaces between medical devices and the exterior physiological environment to improve the performance of medical devices. Herein, we report the first primary S-nitrosothiol-based NO-releasing silicone oil (RSNO-Si) that exhibits proactive antibacterial effects. S-nitrosothiol silicone oils (RSNO-Si) were synthesized and the NO payloads ranged from 34.0 to 603.9 µM. The increased NO payload induced higher-viscosity RSNO-Si oils, as RSNO0.1-Si, RSNO0.5-Si, and RSNO1-Si had viscosities of 12.8 ± 0.1 cP, 32.0 ± 0.2 cP, and 35.1 ± 0.3 cP, respectively. RSNO-Si-SR interfaces were fabricated by infusing silicone rubber (SR) in RSNO-Si oil, and the resulting RSNO-Si-SR disks demonstrated NO release without NO donor leaching. RSNO0.1-Si-SR, RSNO0.5-Si-SR, and RSNO1-Si-SR exhibited maximum NO flux at 0.8, 6.5, and 21.5 × 10 -10 mol cm-2 min-1 in 24 h, respectively. RSNO-Si-SR disks also demonstrated 97.45, 95.40, and 96.08% of inhibition against S. aureus in a 4 h bacterial adhesion assay. Considering the easy synthesis, simple fabrication of non-leaching NO-releasing interfaces, tunable payloads, NO flux levels, and antimicrobial effects, RSNO-Si oils exhibited their potential use as platform chemicals for creating antimicrobial medical device surfaces and other antibacterial materials.

Biomimetic multilayer polycaprolactone/sodium alginate hydrogel scaffolds loaded with melatonin facilitate tendon regeneration.

Tendon injury is one of the most common musculoskeletal diseases in the world, severely challenging the public health care system. Electrospinning technique using polymer materials (i.e. polycaprolactone (PCL)) and hydrogels (i.e. sodium alginate (ALG)) contribute to the development and application of smart composite scaffolds in the tendon tissue engineering by advantageously integrating mechanical properties and biocompatibility. As a potential natural antioxidant, melatonin (MLT) represents the potential to promote tendon repair. Here, we develop an MLT-loaded PCL/ALG composite scaffold that effectively promotes tendon injury repair in vivo and in vitro via a controlled release of MLT, possibly mechanically relying on an antioxidant stress pathway. This biomimetic composite scaffold will be of great significance in the tendon tissue engineering.

Graphene Family Nanomaterials for Stem Cell Neurogenic Differentiation and Peripheral Nerve Regeneration.

Stem cells play a critical role in peripheral nerve regeneration. Nerve scaffolds fabricated by specific materials can help induce the neurogenic differentiation of stem cells. Therefore, it is a potential strategy to enhance therapeutic efficiency. Graphene family nanomaterials are widely applied in repairing peripheral nerves. However, the mechanism underlying the pro-regeneration effects remains elusive. In this review, we first discuss the properties of graphene family nanomaterials, including monolayer and multilayer graphene, few-layer graphene, graphene oxide, reduced graphene oxide, and graphene quantum dots. We also introduce their applications in regulating stem cell differentiation. Then, we review the potential mechanisms of the neurogenic differentiation of stem cells facilitated by the materials. Finally, we discuss the existing challenges in this field to advance the development of nerve biomaterials.

Electroactive nanomaterials in the peripheral nerve regeneration.

Severe peripheral nerve injuries are threatening the life quality of human beings. Current clinical treatments contain some limitations and therefore extensive research and efforts are geared towards tissue engineering approaches and development. The biophysical and biochemical characteristics of nanomaterials are highly focused on as critical elements in the design and fabrication of regenerative scaffolds. Recent studies indicate that the electrical properties and nanostructure of biomaterials can significantly affect the progress of nerve repair. More importantly, these studies also demonstrate the fact that electroactive nanomaterials have substantial implications for regulating the viability and fate of primary supporting cells in nerve regeneration. In this review, we summarize the current knowledge of electroconductive and piezoelectric nanomaterials. We exemplify typical cellular responses through cell-material interfaces, and the nanomaterial-induced microenvironment rebalance in terms of several key factors, immune responses, angiogenesis and oxidative stress. This work highlights the mechanism and application of electroactive nanomaterials to the development of regenerative scaffolds for peripheral nerve tissue engineering.

Nanoparticles based on polymers modified with pH-sensitive molecular switch and low molecular weight heparin carrying Celastrol and ferrocene for breast cancer treatment.

Triple negative breast cancer (TNBC) metastasis is still one of the obstacles in clinical treatment, while highly-effective cancer drugs usually cannot be used for their hydrophobicity and comprehensive system toxicity. This study built a kind of pH-sensitive nanoparticles (PP/H NPs) constructed by poly (lactic-co-glycolic acid) modified with ß-cyclodextrin (PLGA-ß-CD), polyethyleneimine grafted with benzimidazole (PEI-BM) and low molecular weight heparin (LMWH) to delivery Celastrol (Cela) and ferrocene (Fc) for breast cancer therapy. PLGA-ß-CD and PEI-BM were synthesized by amidation reaction, the amphipathic polymer nanoparticles with 108.37 ± 1.02 nm were self-assembled in water. After PP/H NPs treatment, the half maximal inhibitory concentration (IC50) decreased by 91% compared with Cela, and ROS level was also elevated. PP/H NPs led to substantial tumor inhibiting rate (TIR, 65.86%), utilized LMWH to strengthen the anti-metastasis effect of PP/H NPs. PP/H NPs took advantage of exogenous chemotherapeutics and endogenous ROS to inhibit tumor growth, and combined with LMWH to hinder breast cancer metastasis.

Biological and biocompatible characteristics of fullerenols nanomaterials for tissue engineering.

Fullerenes, as hydrophobic molecules, are limited in biomedical function due to their very low solubility. But taking C60(OH)ₓ as an example, the properties of fullerenols were analyzed. It was found that fullerenols had good stability, water solubility, good biocompatibility and low cytotoxicity by adding a hydroxyl group to carbon atoms. In the biomedical field, it has been found that fullerene C60 can be used as a powerful free radical scavenger, with antioxidant activity, with antibacterial and inhibitory effects on cancer cells. Fullerenols inherit the good properties of fullerenes, and are better used in cancer treatment, including loading drug therapy and directly as an anticancer drug. In addition, fullerenols are also used in the repair of myocardial injury, the treatment of myocardial infarction and neuroprotection. With the development of tissue engineering technology, the preparation of nerve scaffolds which can improve ischemia, hypoxia and oxidative stress after nerve injury has become a research hotspot. The electron absorption and reduction characteristics of fullerenols in biomedical research bring new ideas for the treatment of oxidative stress in the repair of peripheral nerve defects. It seems that the research on fullerenols loaded neural scaffold has great prospects.

Elastase-triggered H2S delivery from polymer hydrogels.

We report an elastase-responsive, H2S-releasing hydrogel prepared by covalently crosslinking a mixture of carboxymethylcellulose and poly(ethylene glycol) with an elastase-degradable peptide functionalized with an H2S-releasing S-aroylthiooxime (SATO) unit. Addition of elastase triggered a gel-to-sol transition, which exposed SATOs, leading to more and longer H2S release compared to untriggered gels.

(-)-Epigallocatechin gallate-loaded polycaprolactone scaffolds fabricated using a 3D integrated moulding method alleviate immune stress and induce neurogenesis.

OBJECTIVES: In peripheral neuropathy, the underlying mechanisms of nerve and muscle degeneration include chronic inflammation and oxidative stress in fibrotic tissues. (-)-Epigallocatechin gallate (EGCG) is a major, active component in green tea and may scavenge free radical oxygen and attenuate inflammation. Conservative treatments such as steroid injection only deal with early, asymptomatic, peripheral neuropathy. In contrast, neurolysis and nerve conduit implantation work effectively for treating advanced stages. MATERIALS AND METHODS: An EGCG-loaded polycaprolactone (PCL) porous scaffold was fabricated using an integrated moulding method. We evaluated proliferative, oxidative and inflammatory activity of rat Schwann cells (RSCs) and rat skeletal muscle cells (RSMCs) cultured on different scaffolds in vitro. In a rat radiation injury model, we assessed the morphological, electrophysiological and functional performance of regenerated sciatic nerves and gastrocnemius muscles, as well as oxidative stress and inflammation state. RESULTS: RSCs and RSMCs exhibited higher proliferative, anti-oxidant and anti-inflammatory states in an EGCG/PCL scaffold. In vivo studies showed improved nerve and muscle recovery in the EGCG/PCL group, with increased nerve myelination and muscle fibre proliferation and reduced macrophage infiltration, lipid peroxidation, inflammation and oxidative stress indicators. CONCLUSIONS: The EGCG-modified PCL porous nerve scaffold alleviates cellular oxidative stress and repairs peripheral nerve and muscle structure in rats. It attenuates oxidative stress and inflammation in vivo and may provide further insights into peripheral nerve repair in the future.

PLGA microsphere-mediated growth hormone release hormone expression induces intergenerational growth.

To improve animal growth, growth hormone-releasing hormone (GHRH) expression vectors that maintain constant GHRH expression can be directly injected into muscles. To deliver the GHRH expression vectors, biodegradable microspheres have been used as a sustained release system. Although administering GHRH through microspheres is a common practice, the intergenerational effects of this delivery system are unknown. To investigate the intergenerational effects of polylactic-co-glycolic acid (PLGA) encapsulated plasmid-mediated GHRH supplements, pCMV-Rep-GHRH microspheres were injected into pregnant mice. Growth and expression of GHRH were measured in the offspring. RT-PCR and immunohistochemistry reveal GHRH expression 3-21 days post-injection. The proportion of GH-positive cells in the GHRH treated offspring was 48.2% higher than in the control group (P < 0.01). The GHRH treated offspring were 6.15% (P < 0.05) larger than the control offspring. At day 49 post-injection, IGF-I serum levels were significantly higher in the treatment group than in the control group. This study confirms that intramuscular expression of GHRH mediated by PLGA microspheres significantly enhances intergenerational growth.

[A study on the development of English teaching model of stomatology].

With the development of China's economy, the field of stomatology has also made considerable progress. With the increase of people's demand for dental medical support, it is urgent to cultivate stomatological professionals with a more international perspective and international communication and competition in the field of production, teaching and research. Through literature search, this paper addressed the significance and role of English teaching in stomatology, explored the characteristics and advantages of different teaching modes, in order to provide ideas on how to carry out English teaching in stomatology more effectively.

An integrated multi-layer 3D-fabrication of PDA/RGD coated graphene loaded PCL nanoscaffold for peripheral nerve restoration.

As a conductive nanomaterial, graphene has huge potentials in nerve function restoration by promoting electrical signal transduction and metabolic activities with unique topological properties. Polydopamine (PDA) and arginylglycylaspartic acid (RGD) can improve cell adhesion in tissue engineering. Here we report an integrated 3D printing and layer-by-layer casting (LBLC) method in multi-layered porous scaffold fabrication. The scaffold is composed of single-layered graphene (SG) or multi-layered graphene (MG) and polycaprolactone (PCL). The electrically conductive 3D graphene scaffold can significantly improve neural expression both in vitro and in vivo. It promotes successful axonal regrowth and remyelination after peripheral nerve injury. These findings implicate that graphene-based nanotechnology have great potentials in peripheral nerve restoration in preclinical and clinical application.

One-pot construction of a twice-condensed pDNA polyplex system for peripheral nerve crush injury therapy.

Non-viral vector gene delivery is generally limited by its potential toxicity problems, poor transfection abilities, serum stability, or relatively complex construction processes of modified polyplexes. Thus, we develop an efficient and stable polyplex system through convenient construction methods. Here, polyethyleneimine (PEI) 1.8 kDa and glutaraldehyde (GA) are used to construct a novel twice-condensed pDNA polyplex system using a one-pot construction method, including pH-responsive C[double bond, length as m-dash]N linkages by which different PEI molecules on one single polyplex can link with each other. In this system, smaller particle sizes, higher zeta potentials and better serum stabilities are achieved without PEGylation or other chemical modifications using lyophobic segments, but via pH-responsive linkages that ensure the escape of nucleic acids. This polyplex system is used to deliver the pDNA of vascular endothelial growth factor (VEGF) whose half-life period in vivo is only around 30 minutes. Compared with polyplexes prepared using PEI 25 kDa, cells and rats treated with twice-condensed VEGF pDNA polyplexes express significantly more VEGF or myelin basic protein (MBP), and this new polyplex system showed fewer adverse effects in vitro and in vivo. In addition, revascularization and neurogenesis are also discovered in the rat sciatic nerve crush injury model.

[The therapeutic effects of pegasys in chronic hepatitis B patients with low-level ALT].

OBJECTIVE: To observe the therapeutic effects of Pegasys (pegylated interferon alpha-2a) in chronic hepatitis B (CHB) patients with low-level alanine transaminase (ALT) < 2 x upper limit of normal (ULN). METHODS: One hundred and seven CHB patients were randomized enrolled including 52 with ALT < 2 x ULN and liver tissues inflammation activity > or = G2 as observational group and 55 with ALT > 2 x ULN as control group. All the enrolled patients received pegasys treatment for 48 weeks and the responses between two groups were compared. Measurement data were analyzed using t test and numeration data were analyzed using chi square test. RESULTS: The reductions of HBV DNA in observational group at different time points were all less than control group (all P < 0.05). At the end of treatment, the HBV DNA negative rate, HBeAg seroconversion rate and HBsAg loss rate in the observational group were 51.9%, 48.8% and 1.9% , respectively, which were all lower than control group (67.3% , 66.7% and 7. 3% , respectivley) ( all P <0. 05). The ALT normalization rates of two groups were 75% and 76.4% (P > 0. 05). CONCLUSION: Pegasys is efficient for CHB patients with ALT < 2 x ULN and liver tissues inflammation activity > or = G2, while it is still inferior to those with ALT > 2 x ULN.