Recently,a fast developing new technology for gene modification named as CRISPR-Cas9 which based on CRISPR-Cas9 system composed of clustered regulatory interspaced short palindromic repeat(CRISPR) and Cas9 nuclease(CRISPR associated system 9,Cas9)has been developed. CRISPR-Cas9 system is a kind of immune mechanism widely found in bacteria and archaea. This mechanism can help bacteria and archaea against exogenous DNA by the approach of specifically breaking DNA. Later,this mechanism was found to be useful for gene modification and gene deletion. At present,this technology has been applied to gene modification and therapy. Many studies have shown that the technology,compared with other genetic technology,has higher efficiency and accuracy,and it has promoted genetic engineering progress. Summarized here is the principle and application advance of CRISPR-Cas9.

Objective To investigate the effect of calpeptin on diaphragmatic injury and atrophy under controlled mechanical ventilation in rats.Methods A total of 24 SPF Sprague-Dawley (SD) rats were randomly divided into anesthetized control group (CON group),24-hour controlled mechanical ventilation group (CMV group),and 24-hour CMV + treatment with calpeptin group (CMVC group),with 8 rats in each group.Animals in the CON group received an intraperitoneal injection of pentobarbital sodium without CMV and continuous infusion of pentobarbital sodium.A small-animal ventilator was used for 24 hours in rats of CMV group.Rats of CMVC were treated with a specific calpain inhibitor calpeptin (4 mg/kg).The drug was injected subcutaneously 2 hours before and 8,15 and 23 hours after mechanical ventilation.Changes in diaphragm ultrastructure,light microscopic picture,and myosin heavy chain (MHC) expression were observed.Results ① Alignment of myofilaments and normal Z-band,and the shape of mitochondria were maintained in CON group as revealed by electron microscope.The signs of misalignment of myofibrils,disruption of Z-band and vacuolar mitochondria were found in CMV group,and they were obviously improved in CMVC group.The density of muscle injury (× 10-2/μm2) in CMV group was significantly higher than that in control group (36.8 ± 13.7 vs.6.4 ± 6.3,t=6.373,P=0.001),and that in CMVC group was significantly lowered (17.6 ± 9.1 vs.36.8 ± 13.7,t=3.694,P=0.002).② In CON group,the diaphragm fibers appeared regular in cross section without pathologic change under light microscopy.Fuzzy muscle striations,irregular muscle fibers,centralized nuclei and swelling of capillary endothelial cells were observed in CMV group,while pathological changes in the CMVC group were milder significantly.③ In CMV group,the density of MHCslow and MHCfast was lower compared with that of CON group,and the gray value was lowered by 61.1％ (t=8.138,P=0.001) and 77.1％ (t=8.844,P=0.001),respectively,especially in MHCfast.However,the gray values of MHCslow and MHCfast were increased by 1.51 folds (t=4.601,P=0.010),and 1.33 folds (t=2.859,P=0.011),respectively,after treatment with calpeptin,and the elevation was more significantly in MHCslow.Conclusions Diaphragmatic injury and atrophy were found after CMV for 24 hour.Calpeptin could reverse the detrimental effects of CMV,and it suggested that calpain plays an important role in modulating the ventilator-induced dysfunction of the diaphragm.

AIM: To observe the clinical and multimodal imaging features of retinopathy associated with novel coronavirus disease 2019(COVID-19)infection, investigate the related risk factors, and analyze the treatment and prognosis.METHODS: A total of 7 patients(7 eyes)with clinically confirmed COVID-19-associated retinopathy in Tianjin Medical University General Hospital from December 13, 2022 to January 13, 2023 were included in the study. All patients underwent color fundus photography, IR, spectral-domain optical coherence tomography(SD-OCT), fundus autofluorescein(FAF)and other ophthalmic examination and serological examination.RESULTS: Among the included patients, 2 cases(2 eyes)of central retinal vein occlusion(CRVO)appeared differently from previous CRVO. The hemorrhagic features of CRVO were round or fusiform shape hemorrhagic spots with white centers. One of them, the von Willebrand factor antigen(vWF: Ag)level was increased to 161.8%. The other case was positive in serologic test for lupus anticoagulant. In 2 cases(2 eyes)of multiple evanescent white dot syndrome(MEWDS), FAF showed that dots of high spontaneous fluorescence were scattered in the posterior pole. The prognosis of 2 MEWDS were good after the treatment of glucocorticoids. The 3 cases(3 eyes)of acute macular neuroretinopathy(AMN)showed reddened brown lesions in the macular area, hyporeflective lesions with clear boundaries on IR, and high signal intensity in the ONL and ELM, EZ/IZ signal fracture on SD-OCT.CONCLUSION: COVID-19 may cause inflammatory storm, involving all layers of retinal tissues and blood vessels, leading to the occurrence of various retinal lesions. Hormone therapy may be effective and the prognosis is good in most cases. Roth spot can be seen in fundus hemorrhage of CRVO, lupus anticoagulant and increased vWF: Ag may be risk factors for CRVO after COVID-19.