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The novel coronavirus 2019 (COVID-19) pandemic represents one of the biggest global health threats in the last two decades, so researchers around the world are searching for solutions and treatments for COVID-19. At the time of writing, there are no specific drugs that have demonstrated suitable effectiveness in treating COVID-19. The current challenge involves designing tools for the prevention, rapid and accurate diagnosis, drug delivery, and effective treatment of this novel coronavirus. In this short review, we discuss how nanotechnology offers new ways to combat COVID-19, and how nanomaterials can be applied to control the COVID-19 outbreak. We also summarize relevant studies regarding the use of nanomaterials for preventing viral spread, preparing vaccines, and diagnosing coronavirus, as well as studies that show how nanoparticles can be used as drug delivery systems for the treatment of viral infections. Research on nanotechnology-based diagnosis, drug delivery, and antiviral therapy is currently in the early stages. However, the unique chemical properties of some nanomaterials highlight the broad prospect of nanomaterials in the future, and we propose that they will play an important role in the fight against COVID-19.新型冠状病毒-2019(COVID-19)大流行是过去20年最大的全球健康威胁之一, 因此世界各地的研究人员正在寻找COVID-19的解决方案和治疗方法。截至到撰写本文的时候, 研究人员发现还没有有效治疗COVID-19的特定药物。现阶段研究人员所面临的主要挑战是设计预防这种新型冠状病毒、快速准确诊断、药物传递和有效治疗的纳米工具。我们在这篇简短的综述中讨论了纳米技术如何为抗击COVID-19提供新方法, 还讨论了纳米材料如何应用于控制COVID-19爆发。同时, 我们还总结了纳米材料在预防COVID-19病毒传播、制备疫苗、诊断冠状病毒等方面的相关研究, 以及纳米材料作为药物递送系统治疗该病毒感染的研究。现阶段, 基于纳米技术的诊断、药物传递和抗病毒治疗的研究还处于早期阶段。然而, 一些纳米材料独特的化学性质凸显了纳米材料在未来的广阔前景, 我们认为它们将在抗击COVID-19中发挥十分重要的作用。.

Group A Streptococcus (GAS) is a strict human pathogen causing more than 700 million infections globally each year. The majority of the disease-causing GAS are encapsulated, which greatly guarantees survival and dissemination in the host. Emergence of the capsule-negative GAS, such as M4 GAS, in recent epidemiologic surveillance alarms the necessity to elucidate the virulence determinants of these pathogens. Here, we found that M4 pili play an important role in promoting M4 GAS adherence and cytotoxicity to human pharyngeal epithelial cells and keratinocytes. The same molecule also significantly enhanced M4 GAS survival and replication in human whole blood and experimental murine infection. T4 antigen, which composes the backbone of M4 pili, was able to sequester the very abundant serum protein haptoglobin to further confer M4 GAS resistance to antibacterial substances released by neutrophils and platelets., Streptococcus pyogenes (group A Streptococcus [GAS]) is an important human pathogen causing a broad spectrum of diseases and associated with significant global morbidity and mortality. Almost all GAS isolates express a surface hyaluronic acid capsule, a virulence determinant that facilitates host colonization and impedes phagocyte killing. However, recent epidemiologic surveillance has reported a sustained increase in both mucosal and invasive infections caused by nonencapsulated GAS, which questions the indispensable role of hyaluronic acid capsule in GAS pathogenesis. In this study, we found that pilus of M4 GAS not only significantly promotes biofilm formation, adherence, and cytotoxicity to human upper respiratory tract epithelial cells and keratinocytes, but also promotes survival in human whole blood and increased virulence in murine models of invasive infection. T4 antigen, the pilus backbone protein of M4 GAS, binds haptoglobin, an abundant human acute-phase protein upregulated upon infection and inflammation, on the bacterial surface. Haptoglobin sequestration reduces the susceptibility of nonencapsulated M4 GAS to antimicrobial peptides released from activated neutrophils and platelets. Our results reveal a previously unappreciated virulence-promoting role of M4 GAS pili, in part mediated by co-opting the biology of haptoglobin to mitigate host antimicrobial defenses.

Although many studies have shown the antitumor properties of Cordyceps militaris (artificial cultivated from Bombyx mori pupa) polysaccharides, little is known regarding the mechanism of its effects. This study was conducted to determine the mechanism of antitumor effects of C. militaris polysaccharide extract by evaluating apoptosis rate and cell cycle progression status in human liver cancer cell SMMC-7721, stomach cancer cell BGC-823 and breast cancer cell MCF-7. Results showed that C. militaris polysaccharides inhibited proliferation of SMMC-7721, BGC-823 and MCF-7 cells with an IC 50 of 192 ± 23.2 μg/mL, 237 ± 12.7 μg/mL and 165 ± 16.3 μg/mL, respectively. We also found that C. militaris polysaccharides at increasing concentrations induced apoptosis dose dependently in those cancer cells: apoptosis rates were 48.3%, 59.4% and 70.9% for SMMC-7721, 41.3% and 57.0%, 72.2% for BGC-823 and 61.3%, 66.9% and 80.6% for MCF-7 at 110, 156 and 323 mg/mL of C. militaris polysaccharides, respectively. C. militaris polysaccharides arrested SMMC-7721, BGC-823 and MCF-7 cells at G 0 /G 1 and G 2 /M phases with corresponding decrease in S-phase. This study suggests that C. militaris polysaccharides may exert its antitumor effects in those cancer cells by suppressing its growth, arresting the G 0 /G 1 -phase, reducing DNA synthesis and inducing apoptosis.

As a key component of heavy five-axis linkage CNC machine tools, the existing mechanical biaxial rotary milling heads are usually driven by worm gear, timing belt, or multi-stage gears. Worm gear is inefficiency to transmit motion, hard to maintain the accuracy and difficult to eliminate all clearance; Timing belt can be seriously worn and cannot maintain good accuracy; and multi-stage gears transmission has defects such as long chain, low transmission stiffness. This paper aims at designing a biaxial rotary milling head with large output torque of 3000Nm, high precision and high rigidity. So a new design for biaxial rotary milling head with mechanical spindle, gear transmission and swinging fork structure is proposed. An integral supporting axis is applied to increase the rigidity of A-axis; through the closed numerical loop control based on precise encoder and the decoupling technology of feed motion of A/C axis, the contradiction between large reduction ratio and high precision transmission is solved, and then the requirement of high positioning accuracy (10") is met. Theoretical calculation and simulated analysis shown, the new design not only can guarantee transmission accuracy and dynamic characteristics of biaxial rotary milling head, but also can improve its structural stiffness and meet the high demands of large torque, high precision and high rigidity.

Telomeres form the ends of eukaryotic chromosomes and serve as protective caps that keep chromosomes structure independency and completeness. The first plant telomere DNA was isolated from Arabidopsis thaliana and was shown to have tandemly repeated sequence 5′-TTTAGGG-3′. The Arabidopsis -type telomere has been found in many plants, but several reports indicate that this sequence is absent in some plants. Up to now, no research has been conducted on the telomere of cotton. In this paper, the Arabidopsis -type telomere sequence was amplified and cloned using the primers designed based on the fragment containing telomere sequence in an Arabidopsis bacterial artificial chromosome (BAC). Fluorescence in situ hybridization (FISH) with cotton metaphase chromosomes using the Arabidopsis-type telomere sequence as probes indicated that the signals were located at all chromosome ends of seven diploid and two tetraploid cotton species with different signal intensities among chromosome complements of different cotton species, even between long and short arms of the same chromosome. To identify the signals of FISH, the genome DNA of Xinhai 7, a cultivar of Gossypium barbadense , digested by BAL-31 nuclease was introduced in this study. The result of BAL-31 digestion indicated that the hybridization signals of FISH represent the outermost DNA sequence of each cotton chromosomes. So we first proved that the telomeric repeats of cotton cross-hybridize with that of Arabidopsis. The results of terminal restriction fragment (TRF) showed significant variation in telomere length among cotton species. The telomere length of cultivated cotton was close to 20 kb and was larger than those of wild cotton species whose telomere length ranged from 6 to 20 kb.

Objective To determine the effects of increased ultrasound probe pressure and maternal Valsalva maneuver (VM) on the middle cerebral artery (MCA) Doppler ultrasonography in fetuses. Methods A total of 120 healthy pregnant women in second and third trimesters were enrolled in the study. MCA blood flow was measured by pulsed Doppler sonography in 60 fetuses (24 and 40 weeks' gestation) before and after the application of increased ultrasound probe pressure. In the other 60 fetuses (32 and 36 weeks' gestation), sonography was performed before and after maternal VM. Statistical analysis was performed by paired t-test. Results The pressure induced by the ultrasound probe induced a significant increase in the pulsatility index (PI), resistance index (RI), and peak systolic velocity (PSV); however, a significant decrease was found in the end-diastolic velocity (EDV) (p < 0.05). No statistically significant difference was found in the mean flow velocity (MFV). Moreover, maternal VM did not have any effect on the PI, RI, EDV, or MFV. Conclusion Fetal MCA Doppler assessment is affected by increased probe pressure but not by maternal VM. Thus, the application of the MCA Doppler sonography should be undertaken in the head of fetuses without any probe pressure and without maternal VM. Copyright © 2010 John Wiley & Sons, Ltd.

Background: Many plants possess antioxidants that exhibit additive or synergistic activities. Objective: In this study, an ethanol-extracted flavonoid extracted from mulberry fruit (FEM) was evaluated for the antioxidant activity in vitro and the hemolysis in red blood cell (RBC) and lipid peroxidation in liver in vivo. Materials and Methods: Antioxidant activities in vitro were measured by quantifying its 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, reducing power, and Fe2+-chelating ability. FEM inhibits hemolysis in RBCs and effects of lipid peroxidation in the liver were estimated. Results: The total content of flavonoid compounds was 187.23 mg of quercetin equivalents per grams dried material. In the in vitro assays, FEM demonstrated a strong antioxidant effect, especially in DPPH scavenging activity and reducing power. Mouse RBC hemolysis induced by H2O2 was significantly inhibited by FEM in a dose- and time-dependent manner. The effects of FEM on lipid peroxidation in liver, mitochondria, and microsome were investigated. The percentage of inhibition at high concentration (100 μg/mL) of FEM was 45.51%, 39.36%, and 42.78% for liver, mitochondria, and microsomes, respectively. These results suggest that the FEM possesses a strong antioxidant activity both in vivo and in vitro. SUMMARY The total content of flavonoid compounds in mulberry fruit was 187.23 mg/g dried materialFEM showed a strong antioxidant effect, especially in 2,2-diphenyl-1-picrylhydrazyl scavenging activity and reducing powerMouse red blood cell hemolysis induced by H2O2 was significantly inhibited by FEM in a dose- and time-dependent mannerThe inhibition percentage at high concentration of FEM was 45.51%, 39.36%, and 42.78% for mouse’s liver, mitochondrial, and microsomes, respectively. Abbreviations used: FEM: Flavonoid Extracted from Mulberry fruit, H2O2: Hydrogen peroxide, DPPH: 2,2-diphenyl-1-picrylhydrazyl, EDTA: Ethylene diamine tetraacetic acid, MDA: malondialdehyde, TBA: 2-thiobarbituric acid, RBC: Red blood cells, DNJ: 1-deoxynojirimycin, LDL: low density lipoprotein, ROS: reactive oxygen species, EDTA2Na: Ethylenediaminetetraacetic acid disodium salt.

Background The differential diagnosis for hereditary ataxia encompasses a variety of diseases characterized by both autosomal dominant and recessive inheritance. There are no curative treatments available for these neurodegenerative conditions. This open label treatment study used human umbilical cord blood-derived mononuclear cells (CBMC) combined with rehabilitation training as potential disease modulators. Methods 30 patients suffering from hereditary ataxia were treated with CBMCs administered systemically by intravenous infusion and intrathecally by either cervical or lumbar puncture. Primary endpoint measures were the Berg Balance Scale (BBS), serum markers of immunoglobulin and T-cell subsets, measured at baseline and pre-determined times post-treatment. Results A reduction of pathological symptoms and signs was shown following treatment. The BBS scores, IgG, IgA, total T cells and CD3+CD4 T cells all improved significantly compared to pre-treatment values (P < 0.01~0.001). There were no adverse events. Conclusion The combination of CBMC infusion and rehabilitation training may be a safe and effective treatment for ataxia, which dramatically improves patients' functional symptoms. These data support expanded double blind, placebo-controlled studies for these treatment modalities.