Refined polysaccharide from Dendrobium devonianum resists H1N1 influenza viral infection in mice by activating immunity through the TLR4/MyD88/NF-κB pathway.

Dendrobium polysaccharide exhibits multiple biological activities, such as immune regulation, antioxidation, and antitumor. However, its resistance to viral infection by stimulating immunity is rarely reported. In this study, we explored the effect and mechanism of DVP-1, a novel polysaccharide from Dendrobium devonianum, in the activation of immunity. After being activated by DVP-1, the ability of mice to prevent H1N1 influenza virus infection was investigated. Results of immune regulation showed that DVP-1 significantly improved the immune organ index, lymphocyte proliferation, and mRNA expression level of cytokines, such as IL-1ß, IL-4, IL-6, and TNF-α in the spleen. Immunohistochemical results showed that DVP-1 obviously promoted the mucosal immunity in the jejunum tissue. In addition, the expression levels of TLR4, MyD88, and TRAF6 and the phosphorylation levels of TAK1, Erk, JNK, and NF-κB in the spleen were upregulated by DVP-1. The virus infection results showed that the weight loss of mice slowed down, the survival rate increased, the organ index of the lung reduced, and the virus content in the lung decreased after DVP-1 activated immunity. By activating immunity with DVP-1, the production of inflammatory cells and inflammatory factors in BALF, and alveolar as well as peribronchiolar inflammation could be prevented. The results manifested that DVP-1 could resist H1N1 influenza virus infection by activating immunity through the TLR4/MyD88/NF-κB pathway.

The heterogeneous mixing model of COVID-19 with interventions.

The emergence of mutant strains of COVID-19 reduces the effectiveness of vaccines in preventing infection, but remains effective in preventing severe illness and death. This paper established a heterogeneous mixing model of age groups with pharmaceutical and non-pharmaceutical interventions by analyzing the transmission mechanism of breakthrough infection caused by the heterogeneity of protection period under the action of vaccine-preventable infection with the original strain. The control reproduction number Rc of the system is analyzed, and the existence and stability of equilibrium are given by the comparison principle. Numerical simulation was conducted to evaluate the vaccination program and intervention measures in the customized scenario, demonstrating that the group-3 coverage rate p3 plays a key role in Rc. It is proposed that accelerating the rate of admission and testing is conducive to epidemic control by further fitting data of COVID-19 transmission in real scenarios. The findings provide a general modeling idea for the emergence of new vaccines to prevent infection by mutant strains, as well as a solid theoretical foundation for mainland China to formulate future vaccination strategies for new vaccines. This manuscript was submitted as part of a theme issue on "Modelling COVID-19 and Preparedness for Future Pandemics".

The effectiveness of pedicle screw immersion in vancomycin and ceftriaxone solution for the prevention of postoperative spinal infection: A prospective comparative study.

OBJECTIVE: The aim of this study was to evaluate the efficacy of the local application of vancomycin hydrochloride (HCl)-ceftriaxone disodium hemiheptahydrate onto implants before using them to prevent postoperative infection. METHODS: The study included 239 patients (153 women and 86 men; mean age: 48.23 ± 16.77 years) who had thoracolumbar stabilization with transpedicular screws. All surgeries were performed by the same surgeon. Patients were divided into two groups. In the group 1 (n = 104), implants were bathed in a solution of local prophylactic antibiotics for 5 seconds just before implantation. In the group 2 (n = 135), implants were not bathed before implantation. Local antibiotics used in the study was effective against gram positive bacteria (including methicillin resistant Staphylococcus aureus) and gram negative bacteria. The rate of surgical site infection and wound healing time were compared between the groups. RESULTS: A total of 10 patients (4.1%) had deep wound infection and 20 (8.4%) had superficial infection. The most common bacteria was Staphylococcus aureus. One patient died 21 days after the surgery because of sepsis. The wound healed in a mean of 9.66 ± 2.04 days in patients who had no infection and in 32.33 ± 19.64 days in patients with infection (p < 0.001). The patients in group 1 had significantly less deep infection than the patients in group 2 (p < 0.05). However, there was no statistically significant difference between the groups for superficial infection. Patients with vertebral fracture had significantly lower deep infection rate in group 1. The deep infection rate of group 1 patients with diabetes, with bleeding of more than 2000 mL, transfused with blood transfusions above 3 units and with dural injury was significantly lower than those in the group 2. None of the patients had allergic reactions to the drugs used for local prophylaxis. CONCLUSIONS: This study shown that bathing implants in antibiotics solution was an effective local prophylactic method to prevent deep infections in spinal surgeries with instrumentation. LEVEL OF EVIDENCE: Level III, Therapeutic study.