Objective To elucidate the kinetic characteristics of viral replication and transcription,an in vitro model of viral replication and transcription was established.Utilizing single-molecule magnetic tweezers technology,the dynamic process of SARS-CoV-2 RNA-dependent RNA polymerase(RdRp)during in vitro replication and transcription was investigated.Methods The force field of the single-molecule magnetic tweezer system was corrected using DNA fragments,followed by the construction of RNA fragments to explore the kinetics of RdRp replication and transcription in vitro.Results The force field calibration results were consistent with the worm-like chain model(WLC).The ssRNA strand was found to be approximately 0.3 pm longer than the dsRNA strand and could be stably extended under a 30 pN force field.The average synthesis rate of RdRp extension was determined to be 3.27 nt/s,with an average processivity of 886 nt.Conclusions By implementing force calibration in single-molecule magnetic tweezers,the real-time tracking of RdRp kinetics during the full-cycle replication-transcription process(initiation,elongation,and termination)in vitro was achieved,thereby constructing a mechanistic model of RdRp-driven nucleic acid synthesis.This study provides a basis for further investigating the kinetics of viral RdRp in physiological processes including replication,transcription,and backtracking under varied in vitro environments using single-molecule magnetic tweezers,and establishes a single-molecule manipulation framework for evaluating the effects of therapeutic compounds on viral replication-transcription processes in vitro.

Objective To elucidate the kinetic characteristics of viral replication and transcription,an in vitro model of viral replication and transcription was established.Utilizing single-molecule magnetic tweezers technology,the dynamic process of SARS-CoV-2 RNA-dependent RNA polymerase(RdRp)during in vitro replication and transcription was investigated.Methods The force field of the single-molecule magnetic tweezer system was corrected using DNA fragments,followed by the construction of RNA fragments to explore the kinetics of RdRp replication and transcription in vitro.Results The force field calibration results were consistent with the worm-like chain model(WLC).The ssRNA strand was found to be approximately 0.3 pm longer than the dsRNA strand and could be stably extended under a 30 pN force field.The average synthesis rate of RdRp extension was determined to be 3.27 nt/s,with an average processivity of 886 nt.Conclusions By implementing force calibration in single-molecule magnetic tweezers,the real-time tracking of RdRp kinetics during the full-cycle replication-transcription process(initiation,elongation,and termination)in vitro was achieved,thereby constructing a mechanistic model of RdRp-driven nucleic acid synthesis.This study provides a basis for further investigating the kinetics of viral RdRp in physiological processes including replication,transcription,and backtracking under varied in vitro environments using single-molecule magnetic tweezers,and establishes a single-molecule manipulation framework for evaluating the effects of therapeutic compounds on viral replication-transcription processes in vitro.

Hemichorea associated with non-ketotic hyperglycemia(HC-NH)is a rare complication of diabetes mellitus. It is characterized by sudden and spontaneous non-repeating movements. Clinically, it presents as irregular dance-like movements in the distal parts of one limb, with unilateral involvement being more common and bilateral involvement being rare. Early diagnosis and treatment could improve the prognosis. We report a patient with hyperglycemia who developed bilateral involvement. It highlights the need to consider this condition in diabetic patients who present with secondary involuntary limb movements. Early treatment may lead to reversal of the symptoms.

Objective To investigate the expressions of transmembrane protein 8(Tspan8)and integrin α5(ITGA5)in breast cancer and their relationship with clinicopathological features and prognosis.Methods A total of 136 breast cancer patients admitted to the hospital from April 2018 to April 2020 were enrolled in the study.Breast cancer tissue samples and corresponding paracancerous tissue samples were collected.The ex-pressions of Tspan8 and ITGA5 in breast cancer tissues and corresponding adjacent tissues were detected by immunohistochemistry.The relationship between the expressions of Tspan8 and ITGA5 and the clinicopatho-logical characteristics of breast cancer patients was analyzed.The discharged breast cancer patients were fol-lowed up for 36 months,and the survival status of the patients was recorded.The 3-year survival rate of breast cancer patients with different clinicopathological characteristics was compared.Multivariate Cox regression was used to analyze the influencing factors of axillary lymph node metastasis in breast cancer patients.Results The positive expression rates of Tspan8 and ITGA5 in breast cancer tissues were higher than those in adjacent tissues(P＜0.05).The positive expression rates of Tspan8 and ITGA5 in breast cancer patients with poor differentiation,tumor maximum diameter ≥3 cm,TNM stage Ⅲ-Ⅳ,axillary lymph node metastasis and other molecular subtypes were higher than those in moderate/well differentiation,tumor maximum diam-eter＜3 cm,TNM stage Ⅰ-Ⅱ,no axillary lymph node metastasis and triple negative subtype(P＜0.05).The 3-year survival rate of patients with positive expression of Tspan8 and ITGA5 was significantly lower than that of patients with negative expression of Tspan8 and ITGA5(P＜0.05).The 3-year survival rate of patients with poor differentiation,TNM stage Ⅲ-Ⅳ,axillary lymph node metastasis,other molecular sub-types and positive expressions of Tspan8 and ITGA5 were lower than those of patients with moderate/high differentiation,TNM stage Ⅰ-Ⅱ,no axillary lymph node metastasis,triple negative subtype and negative ex-pressions of Tspan8 and ITGA5(P＜0.05).TNM stage Ⅲ-Ⅳ(HR=2.289,95％CI:1.519-3.447),other molecular subtypes(HR=2.622,95％CI:1.744-3.942),Tspan8 positive expression(HR=3.622,95％CI:2.159-6.077)and ITGA5 positive expression(HR=3.142,95％CI:2.022-4.884)were risk factors for ax-illary lymph node metastasis in breast cancer patients(P＜0.05).Conclusion Tspan8 and ITGA5 are highly expressed in breast cancer patients,which are related to the clinicopathological characteristics and prognosis of patients.

Atomic layer deposition has been employed for postsynthesis treatment of octadecyl bonded silica (ODS) as a typical reversed-phase stationary phase for high performance liquid chromatography (HPLC) ,in an effort to alleviate peak tailing for basic compounds. With hexamethyldisilazane( HMDS) as an endcapping agent,the ODS packing materials were heated to 250℃,and maintained at that temperature for 6 h,affording packing materials which are highly inert to basic compounds. Chromatographic performance in terms of retention factor and tailing factor of the resulting phases was evaluated using phenol/pyridine and naphthalene/ami-triptyline pairs as probes. The results were compared with those for the same packing treated by liquid phase method and for the commercial products including Zorbax SB-C_(18) and Kromasil C_(18). The separation characteristics of the ODS phase obtained by atomic layer deposition appear to be superior to that by liquid phase method and,comparable with or even better than the commercial products studied. Being solvent-free process amenable to mass production,the described method provides an economical and eco-friendly approach to manufacturing HPLC packing materials on industrial scale.