Structure Based Affinity Maturation and Characterizing of SARS-CoV Antibody CR3022 against SARS-CoV-2 by Computational and Experimental Approaches

The COVID-19 epidemic is raging around the world. Neutralizing antibodies are powerful tools for the prevention and treatment of SARS-CoV-2 infection. Antibody CR3022, a SARS-CoV neutralizing antibody, was found to cross-react with SARS-CoV-2, but its affinity was lower than that of its binding with SARS-CoV, which greatly limited the further development of CR3022 against SARS-CoV-2. Therefore, it is necessary to improve its affinity to SARS-CoV-2 in vitro. In this study, the structure-based molecular simulations were utilized to virtually mutate the possible key residues in the complementarity-determining regions (CDRs) of the CR3022 antibody. According to the criteria of mutation energy, the mutation sites that have the potential to impact the antibody affinity were then selected. Then optimized CR3022 mutants with the enhanced affinity were further identified and verified by enzyme-linked immunosorbent assay (ELISA), surface plasma resonance (SPR) and autoimmune reactivity experiments. Finally, molecular dynamics (MD) simulation and binding free energy calculation (MM/PBSA) were performed on the wild-type CR3022 and its two double-site mutants to understand in more detail the contribution of these sites to the higher affinity. It was found that the binding affinity of the CR3022 antibody could be significantly enhanced more than ten times after the introduction of the S103F/Y mutation in HCDR–3 and the S33R mutation in LCDR–1. The additional hydrogen-bonding, hydrophobic interactions, as well as salt-bridges formed between the modified double-site mutated antibody and SARS-CoV-2 RBD were identified. The computational and experimental results clearly demonstrated that the affinity of the modified antibody has been greatly enhanced. This study indicates that CR3022 as a neutralizing antibody recognizing the conserved region of RBD against SARS-CoV with cross-reactivity with SARS-CoV-2, a different member in a large family of coronaviruses, could be improved by the computational and experimental approaches which provided insights for developing antibody drugs against SARS-CoV-2.     

Updated review of genetic reticulate pigmentary disorders

Reticulate pigmentary disorders are a group of disorders characterized by hyper‐ and/or hypopigmented macules with varying sizes and amounts of pigment. Some of the disorders are heritable, such as Dowling‐Degos disease, dyschromatosis universalis hereditaria, dyschromatosis symmetrica hereditaria, reticulate acropigmentation of Kitamura and X‐linked reticulate pigmentary disorder. Although each condition possesses unique phenotypic characteristics and the prognosis for each is somewhat different, there is a large degree of overlap between the disorders and therefore they are difficult to differentiate in the clinical setting. This updated review provides a clinical and molecular delineation of these genetic reticulate pigmentary disorders and aims to establish a concise diagnostic strategy to allow clinical dermatologists to make an accurate diagnosis, as well as to provide useful information for clinical and genetic counselling.     

Backscatter coefficient measurements using a reference phantom to extract depth-dependent instrumentation factors

In previous work, we demonstrated that accurate backscatter coefficient measurements are obtained with a data reduction method that explicitly accounts for experimental factors involved in recording echo data. An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here. This method involves comparison of echo data from a sample with data recorded from a reference phantom whose backscatter and attenuation coefficients are known. A time domain processing technique is used to extract depth and frequency dependent signal ratios for the sample and the reference phantom. The attenuation coefficient and backscatter coefficient of the sample are found from these ratios. The method is tested using tissue-mimicking phantoms with known scattering and attenuation properties.     

Genetic variants in telomere-maintenance genes and bladder cancer risk

Telomere maintenance genes play an important role in maintaining the integrity of the telomere structure that protects chromosome ends, and telomere dysfunction may lead to tumorigenesis. Genetic variation in telomere maintenance genes has been confirmed. Cumulative evidence shows that the difference of telomere length and stability among the indi- vidual depends on the genetic variants of telomere maintenance genes. Genetic variants in telomere maintenance genes may affect telomere length and stability, thus the increased cancer risk. This review intends to summarize the association of genetic variants in telomere maintenance genes with bladder cancer risk.     

缺氧对牙周炎大鼠龈沟液中可溶性细胞间黏附分子-1变化的影响

目的研究平原常氧和模拟高原缺氧条件下慢性牙周炎SD大鼠模型龈沟液(GCF)中可溶性细胞间黏附分子-1(sICAM-1)浓度的变化,以探讨sICAM-1与高原牙周炎的关系。方法选取40只SD大鼠,雌雄各半,分为平原对照组(A组)、平原牙周炎组(B组)、缺氧对照组(C组)、缺氧牙周炎组(D组),每组10只。B、D组大鼠分别建立平原、高原牙周炎模型,A、C组分别作为平原、高原对照组。8周后采用ELISA法检测4组大鼠GCF中sICAM-1浓度变化,并进行比较。结果A、B、C、D组GCF中sICAM-1浓度分别为21.98±2.93、32.20±3.80、23.44±3.81、36.64±2.64ng/ml,B组与A组、D组与C组、C组与A组、D组与B组比较,差异均有统计学意义(P<0.05),其中D组显著高于其他三组(P<0.05)。结论缺氧牙周炎组大鼠GCF中的sICAM-1水平高于平原牙周炎组,提示高原缺氧环境对机体的免疫黏附能力有一定影响。     

血管生成抑制剂Rg3对胃癌生长和转移抑制作用的实验研究

目的：研究血管生成抑制剂Rg3对胃癌生长和转移的抑制作用。方法：完整组织块SCID鼠胃壁原位种植,建立类似于临床的胃癌转移模型。移植后第7天开始灌胃给药,Rg3剂量为0、2．5,5．0,10．0mg/kg,每日1次,共6周,移植后第8周末处死动物,测定原位肿瘤重量,观察转移情况,并采用抗CD31抗体的标记链霉亲和素－生物素免疫组化方法检测肿瘤内微血管密度。结果：Rg3对原位肿瘤的生长和转移均有抑制作用,2．5,5．0,10．0mg/kg剂量组的抑瘤率分别为52．3％,63．3％和71．6％,肝转移抑制率分别为37．8％,68．9％和84．4％,腹膜转移抑制率分别为36．4％,74．6％和74．6％,Rg3治疗后,肿瘤内微血管密度明显降低,结论：Rg3对胃癌的生长和转移有明显抑制作用。     

Computed tomography of aortoiliac atherosclerosis

Twenty-three patients with atherosclerotic peripheral vascular disease underwent angiography and CT of the aortoiliac segment within a 72-hour interval. Examinations were evaluated for depiction of disease in the aortic and iliac segments in five categories: stenosis, plaque morphology, vascular ectasia, calcification, and other pathologic conditions. Angiography and CT were equally accurate in their depiction of the degree of aortic stenosis or occlusion and in identification of aortic ectasia. Angiography proved superior to CT in the display of plaque morphology in 57% of aortic lesions and 74% of iliac abnormalities. Angiography also showed clear superiority over CT in quantification of iliac stenosis in 75% of patients with abnormalities, as well as in identification of iliac ectasia. CT detected both intimal calcification and incidental disease or congenital abnormalities better than angiography, including an unsuspected chronic contained aortic rupture. Overall, CT compared favorably with angiography in the identification of all types of aortic disease but major disadvantages of CT were evident in the iliac segment because of vessel tortuosity or heavy calcification. CT cannot replace arteriography in detecting atherosclerotic disease of the aortoiliac segment but can help to clarify angiographic findings in selected groups of patients.     

Association between the expression of mast cell chymase and intraperitoneal adhesion formation in mice

BACKGROUND: Adhesion formation is a major source of postoperative morbidity and mortality. Mast cells and their major protease, chymase, have been shown to participate in the healing process as well as in tissue remodeling. We aimed to identify the role of mast cells in intraperitoneal adhesion formation and to assess whether there is an association between the expression of mast cell chymase and adhesion formation. MATERIALS AND METHODS: Both mast cell-deficient W/W(V) mice and congenic +/+ mice received a standardized lesion produced by cecal scraping and the application of 95% ethanol. Adhesions were assessed blindly 1 week later using a standardized scale. In addition, histamine content, mast cell numbers, and chymase activity in cecum as well as at the healing sites were evaluated before and 7 days after surgical injury. RESULTS: A significant reduction in adhesion formation was seen in mast cell-deficient W/W(V) mice (P < 0.05). In the normal cecum, histamine content did not significantly differ between W/W(V) and +/+ mice. Chymase activity in cecum was detected in control +/+ mice, but not in W/W(V) mice. Mast cell numbers and chymase activity levels at the healing sites of +/+ mice were significantly increased 7 days after surgery. CONCLUSIONS: Our results indicate that mast cells contribute to intraperitoneal adhesion formation in mice, and suggest that chymase originating from mast cells is important in the development of adhesions.