The variable domain of heavy-chain antibody (VHH) has been developed widely in drug therapy, diagnosis, and research. Escherichia coli is the most popular expression system for VHH production, whereas low bioactivity occurs sometimes. Mammalian cells are one of the most ideal hosts for VHH expression at present. To improve the yield of VHH in Expi293F cells, we optimized the signal peptide (SP) and codons of VHH. Firstly, the fusion protein VHH1-Fc was used to screen SPs. The SP IFN-α2 showed the highest secretion as quantified by enzyme-linked immunosorbent assay (ELISA). Subsequently, codon optimization by improving GC3 and GC content doubled the yield of VHH1 and kept its binding activity to Senecavirus A (SVA). Finally, the mean yields of other 5 VHHs that fused with SP IFN-α2 and codon-optimized were over 191.6 mg/L, and these VHHs had high recovery and high purity in the culture supernatant. This study confirms that SP IFN-α2 and codon optimization could produce VHHs in Expi293F cells efficiently, which provides a reference for the large-scale production of VHHs.
Codon/genetics* ; Protein Sorting Signals/genetics* ; Escherichia coli/metabolism* ; Humans ; Recombinant Fusion Proteins/biosynthesis* ; Interferon-alpha/metabolism* ; Immunoglobulin Heavy Chains/immunology* ; Cell Line ; Immunoglobulin Variable Region/immunology*

Microwave thermal ablation technology is widely used in the treatment of liver tumors because of its minimal invasiveness and small side effects. The precise control of the thermal dose largely determines the therapeutic effect of microwave thermal ablation. However, the current magnetron-based microwave thermal ablation device has the disadvantages of poor power output stability and high operating voltage. In view of the above problems, this paper selected the microwave solid-state source as the core device of microwave output, and designed a dual-frequency microwave thermal ablation system based on 2 450 MHz and 433 MHz. The system used the power detection circuit to perform PID feedback control on the actual output power of the system. The experimental results show that the maximum output power of the system is less than 1 W. The PID algorithm further enhances the accuracy and stability of the system output power while improving the system security. The dual-frequency microwave thermal ablation system designed in this paper can provide a safe and reliable experimental platform for subsequent research.
Catheter Ablation ; instrumentation ; Humans ; Liver Neoplasms ; therapy ; Microwaves ; Radiofrequency Ablation

BACKGROUND:In recent years, pedicle internal fixation, spinal canal decompression and bone graft fusion have been used in the treatment of degenerative lumbar spondylolisthesis complicated by lumbar spinal stenosis and have achieved good results, which increase the fusion rate. However, there is a large difference between the therapeutic effects of different surgical methods. OBJECTIVE:To contrast the repair effect of posterior and transforaminal lumbar interbody fusion on degenerative lumbar spondylolisthesis complicated by lumbar spinal stenosis. METHODS:Forty patients with degenerative lumbar spondylolisthesis complicated by lumbar spinal stenosis were enroled, including 11 males and 29 females, aged 56-74 years. Al patients received the combined treatment of pedicle internal fixation, spinal canal decompression and bone graft fusion. The 19 of 40 patients received posterior lumbar interbody fusion and the rest 21 patients underwent transforaminal lumbar interbody fusion. Al the patients were folowed up for 6 months after treatment, and the visual analog scores, Oswestry function index, bone fusion rate, lumbar function score and complication occurrence were analyzed and
compared between the two groups. RESULTS AND CONCLUSION:The visual analog scores and Oswestry function index were both improved significantly in the two groups at 6 months after treatment (P < 0.05). No difference was found in the bone fusion rate, visual analog scores and Oswestry function index between the two groups. But compared with the posterior lumbar interbody fusion group, the lumbar functional recovery and incidence of complications were better in the transforaminal lumbar interbody fusion group (P < 0.05). These findings indicate that both posterior and transforaminal lumbar interbody fusions for degenerative lumbar spondylolisthesis complicated by lumbar spinal stenosis can achieve good results in the bone fusion rate, and however, the transforaminal lumbar interbody fusion is better to protect the nerve root and dural sac and to promote lumbar functional recovery.