The cellular characterisation of SARS-CoV-2 spike protein in virus-infected cells using Receptor Binding Domain-binding specific human monoclonal antibodies.

A human monoclonal antibody panel (PD4, PD5, PD7, SC23 and SC29) was isolated from the B cells of convalescent patients and used to examine the S protein in SARS-CoV-2- infected cells. While all five antibodies bound conformational-specific epitopes within SARS-CoV-2 Spike (S) protein, only PD5, PD7, and SC23 were able to bind to the Receptor Binding Domain (RBD). Immunofluorescence microscopy was used to examine the S protein RBD in cells infected with the Singapore isolates SARS-CoV-2/0334 and SARS-CoV-2/1302. The RBD-binders exhibited a distinct cytoplasmic staining pattern that was primarily localised within the Golgi complex and was distinct from the diffuse cytoplasmic staining pattern exhibited by the non-RBD binders (PD4 and SC29). These data indicated that the S protein adopted a conformation in the Golgi complex that enabled the RBD recognition by the RBD-binders. The RBD-binders also recognised the uncleaved S protein indicating that S protein cleavage was not required for RBD recognition. Electron microscopy indicated high levels of cell-associated virus particles, and multiple cycle virus infection using RBD-binder staining provided evidence for direct cell-to-cell transmission for both isolates. Although similar levels of RBD-binder staining was demonstrated for each isolate, the SARS-CoV-2/1302 exhibited slower rates of cell-to-cell transmission. These data suggest that a conformational change in the S protein occurs during its transit through the Golgi complex that enables RBD recognition by the RBD-binders, and suggests that these antibodies can be used to monitor S protein RBD formation during the early stages of infection. ImportanceThe SARS CoV-2 spike (S) protein receptor binding domain (RBD) mediates the attachment of SARS CoV-2 to the host cell. This interaction plays an essential role in initiating virus infection and the S protein RBD is therefore a focus of therapeutic and vaccine interventions. However, new virus variants have emerged with altered biological properties in the RBD that can potentially negate these interventions. Therefore an improved understanding of the biological properties of the RBD in virus-infected cells may offer future therapeutic strategies to mitigate SARS CoV-2 infection. We used physiologically relevant antibodies that were isolated from the B cells of convalescent COVID19 patients to monitor the RBD in cells infected with SARS CoV-2 clinical isolates. These immunological reagents specifically recognise the correctly folded RBD and were used to monitor the appearance of the RBD in SARS CoV-2-infected cells and identified the site where the RDB first appears.

Three-dimensional EH composite artificial template for repairing cranial defect in 53 cases / 中国组织工程研究

OBJECTIVE: To observe effects of three-dimensional EH composite template on repairing cranial bone defect. METHODS: A total of 53 inpatients were analyzed retrospectively at the Department of Neurosurgery, Taixing People's Hospital from July 2004 to May 2007, comprising 31 males and 22 females, aged 19-68 years. They were in accordance with cranial repairing indication. Reasons for skull defect: traumatic brain injury (41 cases), hypertension (7 cases), intracranial cancer (3 cases), intracranial aneurysm (2 cases). Thirteen patients developed bilateral cranial defect. The defect region: frontal (5 slices, comprising 2 with severe orbital part defect), temporal (9 slices), frontotemporal (42 slices), temporoparietal (3 slices), parietoocipital (4 slices),frontoparietal (3 slices). The smallest single-chip defect size was 4 cm × 6 cm, and the largest one was 12 cm×18 cm. All the patients were mended by three-dimensional EH composite template using spiral CT (≤5 mm thickness) scanning, CAD three dimensional reconstruction, quickly modeling technique. Infection of incisional wound, rejection and complications were observed. RESULTS: A total of 53 patients were followed up, with an average follow-up period of 18 months, and all of them were satisfied with the shapes (100%). Mild collection of the fluid under the scalp was found in 2 cases 4 days and 1 week following surgery, and disappeared after suction and pressure dressing. No other frequent complications were observed after cranioplasty. CONCLUSION: Three-dimensional EH composite template is an ideal material for cranial bone defect, because of its good biocompatibility, easy operation, good postoperative shape and less complications.

Effects of chromium rutin on metabolism of blood lipid in rats / 中国临床药理学与治疗学

AIM: To study the effects of chromium rutin synthesized with rutin and chromium (Ⅲ) on metabolism of blood lipid. METHODS: The effects of chromium rutin on metabolism of blood lipid were evaluated by the changes of triglyceride, cholesterol, HDL cholesterol, and LDL cholesterol in normal rats and the rats with high blood lipid. RESULTS: Chromium rutin could increase the blood chromium, decrease the concentrations of triglyceride, cholesterlo and LDL cholestelol,and increase the concentration of HDL cholesterol in normal and the rats with high blood lipid rats. CONCLUSION: Chromium rutin has an effect on the blood lipid in rats.