RESUMEN
All subtypes of Clostridium perfringens (C. perfringens) produce the alpha toxin (CPA), which can cause enteritis or enterotoxemia in lambs, cattle, pigs, and horses, as well as traumatic clostridial myonecrosis in humans and animals. CPA acts on cell membranes, ultimately leading to endocytosis and cell death. Therefore, the neutralization of CPA is crucial for the prevention and treatment of diseases caused by C. perfringens. In this study, utilizing CPA as an antigen, a nanobody (CPA-VHH) with a half-life of 2.9 h, an affinity constant (KD) of 0.9 nmol/L, and good stability below 60 °C was prepared from a natural nanobody library from alpacas. The biological activity analysis of CPA-VHH revealed its ability to effectively neutralize the phospholipase and hemolytic activity of CPA at a 15-fold ratio. In Vero cells, 9.8 µg/mL CPA-VHH neutralized the cytotoxicity of CPA at two times the half-maximal inhibitory concentration (IC50). In a mouse model, 35.7 ng/g body weight (BW) of CPA-VHH neutralized 90% of the lethality caused by a 2× median lethal dose (LD50) of CPA. It was found that CPA-VHH protected 80% of mice within 30 min at 2 × LD50 CPA, but this dropped below 50% after 2 h and to 0% after 4 h. Rescue trials indicated that using CPA-VHH within 30 min post-infection with 2 × LD50 CPA achieved an 80% rescue rate, which decreased to 10% after 2 h. Furthermore, CPA-VHH effectively mitigated the reduction in the expression levels of zonula occludens-1 (ZO-1), Occludin, and Claudin-1, while also attenuating the upregulation of the pro-inflammatory cytokines interleukin-1ß (IL-1ß), interleukin-6 (IL-6), interleukin-7 (IL-7), interleukin-8 (IL-8), tumor necrosis factor α (TNF-α), and interferon-γ (IFN-γ) induced by CPA infection. Overall, this study has identified a specific nanobody, CPA-VHH, that effectively neutralizes CPA toxins in vitro and in animal models, providing a new tool for inhibiting the pathogenicity resulting from these toxins and laying an important foundation for the development of new anti-C. perfringens toxin-related therapeutic products.
RESUMEN
The gravity-aided inertial navigation system is a technique using geophysical information, which has broad application prospects, and the gravity-map-matching algorithm is one of its key technologies. A novel gravity-matching algorithm based on the K-Nearest neighbor is proposed in this paper to enhance the anti-noise capability of the gravity-matching algorithm, improve the accuracy of gravity-aided navigation, and reduce the application threshold of the matching algorithm. This algorithm selects K sample labels by the Euclidean distance between sample datum and measurement, and then creatively determines the weight of each label from its spatial position using the weighted average of labels and the constraint conditions of sailing speed to obtain the continuous navigation results by gravity matching. The simulation experiments of post processing are designed to demonstrate the efficiency. The experimental results show that the algorithm reduces the INS positioning error effectively, and the position error in both longitude and latitude directions is less than 800 m. The computing time can meet the requirements of real-time navigation, and the average running time of the KNN algorithm at each matching point is 5.87s. This algorithm shows better stability and anti-noise capability in the continuously matching process.
RESUMEN
This study characterized the properties of NaOH-modified grapefruit peel (MGP) and investigated its adsorption properties, specifically the adsorption of the synthetic dyes neutral red (NR) and malachite green (MG) onto MGP, in single and binary systems by means of batch techniques. The adsorption equilibrium data of NR onto MGP fit well with both the Langmuir and Koble-Corrigan models, while the Koble-Corrigan and Dubinin-Radushkevich models seemed to agree better with MG adsorption. The maximum equilibrium quantities of NR and MG from the Langmuir model were 640.3 and 314.9 mg/g at 298 K, respectively. The Elovich model was a better fit with the kinetic process, which suggested that ion exchange was one of the main mechanisms at work. The thermodynamic parameters of adsorption systems indicated spontaneous and endothermic processes. In the binary system experiments, NR and MG exhibited competitive adsorption. The quantity of MG adsorbed was more strongly influenced by NR, due to the higher affinity of MGP for the latter.