The telomere structure in the cell nucleus is crucial for maintaining the stability and functions of chromosomes.Telomerase is a ribonucleoprotein reverse transcriptase,which catalyzes the elongation of telomeres using its own RNA as a template,thereby counteracting the shortening of telomeres caused by chromosome replication and cell division.Due to its overexpression in over 85％of malignant tumor cells,telomerase has emerged as a highly promising biomarker and a novel target for cancer therapy.In recent years,given the importance of precise quantification of telomerase activity in guiding medical diagnosis and treatment strategies,researchers have developed various high-performance telomerase detection techniques.Among these,electrochemical biosensing technique has cause much attention due to its high sensitivity,operational convenience,rapid response,and ease of miniaturization.This paper focused on the latest advances in electrochemical sensing technique for detection of telomerase activity,aiming to provide inspiration for designing novel telomerase activity detection strategies by elucidating three unique properties of telomerase primer extension products.

Objective To explore the mechanism of myocardial toxicity caused by N-methyl-3,4-methyle-nedioxyamphetamine(MDMA),the changes of intracellular calcium oscillation mode and calcium han-dling proteins during acute exposure to different concentrations of MDMA were detected,and the in-volvement of nuclear factor κB(NF-κB)and its effect on calcium handling proteins were investigated.Methods Primary rat cardiomyocytes were cultured to establish MDMA acute exposure model,and a control group was set up.The MDMA poisoning model was divided into three concentration groups of 10,100 and 1 000 μmol/L.After 1 h of exposure,the morphological changes of cardiomyocytes were ob-served,the cytotoxicity and changes in calcium signals were measured,and the changes in calcium handling proteins RyR2,SERCA2a,PLN,NCX1 and Cav1.2 were detected.The changes of NF-κB activity and the expression of nucleoprotein p-p65(Ser311)and PKCζ after MDMA exposure,and the intervention of NF-κB inhibitors pyrrolidine dithiocarbamate ammonium(PDTC)and protein kinase C(PKC)inhibitor chelerythrine(CHE)were detected by electrophoretic mobility shift assay(EMSA)and Western blotting.The effects of PDTC intervention on calcium signals,and the expressions of RyR2,SERCA2a,PLN,NCX1 and Cav1.2 after acute MDMA exposure were also observed.Results No obvious changes were observed in the morphology of cardiomyocytes after acute exposure to MDMA,whereas the oscillation waveform of intracytoplasmic calcium ion showed irregular changes with increased oscillation amplitude,intense fluctuations,irregular frequency,and increased fluctuation range of relative optical density values.The expression of RyR2,SERCA2a and NCX1 increased,while the expression of Cav1.2 and PLN de-creased.Acute MDMA exposure could increase NF-κB activity,while PDTC and CHE intervention could inhibit NF-κB activity.In MDMA exposed group,the expression of PKCζ and nucleoprotein p-p65(Ser311)both increased and could be inhibited by CHE.After the intervention of PDTC to block NF-κB,the amplitude of calcium oscillation was lower than that of the MDMA exposed group,and the expres-sion of RyR2,SERCA2a and NCX1 decreased.There was no significant change in PLN,while the ex-pression of Cav1.2 increased.Conclusion MDMA can lead to an increase of calcium ion concentration in cardiomyocytes.Calcium ions are involved in myocardial toxicity of MDMA.The mechanism is re-lated to changes in calcium handling proteins,mainly associated with the increased expression of RyR2.MDMA can up-regulate the intracellular activity of NF-κB through the PKCζ-NF-κB pathway and affect calcium handling proteins,which aggravate intracellular calcium overload during acute MDMA exposure.

Aim To explore the influence of demethy-lase fat mass and obesity-related genes(FTO)on the abnormal contractile function of diabetic coronary smooth muscle.Methods Smooth muscle specific FTO knockout mice(FTOSMKO)were prepared by Cre-loxP recombinant technology.They were divided into four groups:control(WT)group,diabetes model group(DM),FTO knockout group(FTOSMKO),and FTOSMKO diabetic group(FTOSMKO-DM),with 15 mice in each group.Diabetic mice were prepared by intraperitoneal injection of streptozotocin(STZ);the remaining mice were injected with an equal amount of citric acid-sodi-um citrate buffer.The effects of 5-HTon the contractile response of coronary artery smooth muscle in the four groups of mice were observed by the technique of small-vessel ring tensiometry.Western blot and Dot blot were used to detect the changes of FTO protein and N6-methyladenine(m6A)methylation modification levels in mouse vascular tissues.Results Compared with the WT group,the DM group had significantly higher blood glucose(P＜0.01)and lower body weight(P＜0.05);the level of FTO protein in aorta of DM group increased(P＜0.01),and the level of m6A methylation modification decreased(P＜0.01).The 5-HT-induced contractile response significantly de-creased in the DM group compared with the WT group(P＜0.01),whereas the contractile response signifi-cantly increased in the FTOSMKO-DM group compared with the DM group(P＜0.01);the non-L-type calci-um channel-mediated vascular smooth muscle contrac-tile response was enhanced in the FTOSMKO-DM group,among which,the contractions induced by 1,4,5-triphosphate inositol receptor(IP3R)and caffeine-ac-tivated ranine receptor(RyR)mediated by sarcoplas-mic reticulum calcium release both significantly in-creased(P＜0.05).Conclusions Specific knock-down of smooth muscle FTO improves coronary artery responsiveness to the vasoconstrictor 5-HT in diabetic mice,which may be related to abnormalities in the FTO-mediated 5-HT receptor signaling pathway.

Aim To explore the influence of demethy-lase fat mass and obesity-related genes(FTO)on the abnormal contractile function of diabetic coronary smooth muscle.Methods Smooth muscle specific FTO knockout mice(FTOSMKO)were prepared by Cre-loxP recombinant technology.They were divided into four groups:control(WT)group,diabetes model group(DM),FTO knockout group(FTOSMKO),and FTOSMKO diabetic group(FTOSMKO-DM),with 15 mice in each group.Diabetic mice were prepared by intraperitoneal injection of streptozotocin(STZ);the remaining mice were injected with an equal amount of citric acid-sodi-um citrate buffer.The effects of 5-HTon the contractile response of coronary artery smooth muscle in the four groups of mice were observed by the technique of small-vessel ring tensiometry.Western blot and Dot blot were used to detect the changes of FTO protein and N6-methyladenine(m6A)methylation modification levels in mouse vascular tissues.Results Compared with the WT group,the DM group had significantly higher blood glucose(P＜0.01)and lower body weight(P＜0.05);the level of FTO protein in aorta of DM group increased(P＜0.01),and the level of m6A methylation modification decreased(P＜0.01).The 5-HT-induced contractile response significantly de-creased in the DM group compared with the WT group(P＜0.01),whereas the contractile response signifi-cantly increased in the FTOSMKO-DM group compared with the DM group(P＜0.01);the non-L-type calci-um channel-mediated vascular smooth muscle contrac-tile response was enhanced in the FTOSMKO-DM group,among which,the contractions induced by 1,4,5-triphosphate inositol receptor(IP3R)and caffeine-ac-tivated ranine receptor(RyR)mediated by sarcoplas-mic reticulum calcium release both significantly in-creased(P＜0.05).Conclusions Specific knock-down of smooth muscle FTO improves coronary artery responsiveness to the vasoconstrictor 5-HT in diabetic mice,which may be related to abnormalities in the FTO-mediated 5-HT receptor signaling pathway.

In industrial production,the expression level of drug proteins in Chinese hamster ovary cells(CHO)is influenced by many factors:the regulatory elements on transcription and translation,the ge-nomic integration sites,and the expression system.Transcription,as the first step of gene expression,largely affects protein expression,and the promoter plays a crucial role in the initiation of transcription.Most of the promoters were screened through transient transfection or random integration,but the presence of unclear copy number or random integration sites makes it difficult to accurately evaluate the promoter activity.To some extent,site-specific integration can reduce the impact of positional effects on exogenous genes and may potentially increase the expression level of exogenous genes.In the early stage of our re-search,multiple sites that can stably express exogenous proteins were identified and verified in the CHO cell genome.In this study,one of these sites(2c6)was selected for the evaluation of promoter activity.The CRISPR/Cas9 gene editing technique was used to site-specifically integrate the reporter gene(EG-FP)regulated by the simian virus early promoter(SV40),mouse elongation factor-1α(mEF-1α),chicken β-actin(cACTB)promoter,and human phosphoglycerate kinase promoter(hPGK)into the 2c6 site,respectively.The mean fluorescence intensity of the cells was analyzed by flow cytometry,and the mRNA level of EGFP was detected by qPCR to comprehensively evaluate the activity of the promoter.The results showed that the activities of the mEF-1α and mACTB promoters were better than those of SV40 and hPGK.The results of the secondary flow cytometry sorting showed that site-specific integration can more accurately evaluate the activity of the promoter in the CHO cell expression system.

Aim To express and purify rhα-Gal A with a 6 X His tag via using a serum-free expression system in high-density suspension culture of Chinese hamster ovary cells ( CHO-S) , and to verify the scavenging effect of rhα-Gal A on globular trisaccharide ceramide (Gb3 or GL3) . Methods The construction of recombinant protein expression vector, pcDNA4-GLA, was achieved by fusing the human α-galactosidase cDNA, gla, with 6 X His tag and artificial DNA synthesis. The expression plasmid was transfected into the suspended CHO-S to express rhα-Gal A and then purified. Following this procedure, we determined rhα-Gal A's expression, the enzymatic activity, and the glycosylation of the recombinant enzyme. Co-incubation with cultured cells was performed to examine whether rhα-Gal A could be taken up into the cells and effectively remove Gb3 substrates. Results rhα-Gal A was successfully expressed and purified after transiently transfecting pcDNA4-GLA into the suspended CHO-S, and the yield was up to (100 ±20. 6) mg • L

Aim To observe the effect of betulinic acid (BA) on the migration and invasion of human gastric cancer MKN-45 cells induced by transforming growth factor-pi (TGF-β1), and to explore the effect of BA on epithelial-mesenchymal transition (EMT) and the potential mechanism. Methods The MKN-45 cells were cultivated in vitro, and the effects of different concentrations of BA on the proliferation of MKN-45 cells at 24, 48 and 72 h were detected using CCK-8 method. The effects of BA (5, 10, 20 jjunol • L) and TGF-01 inhibitor LY2109761 (10 ^mol • L"

AIM: To evaluate the application of optical coherence tomography angiography(OCTA)in diabetic patients without retinopathy(NDR)by Meta-analysis.METHODS: CNKI, WanFang Data, VIP, CBM, PubMed, and Embase databases were searched for relevant studies. The retrieval time was from the establishment of the database to October 2021. Two investigators independently screened the literature, extracted data and evaluated the quality of the included studies using the NOS scale. Meta-analysis and publication bias evaluation was performed using RevMan 5.3 and STATA, and sensitivity analysis was performed for results with large heterogeneity to ensure the accuracy of the results.RESULTS: A total of 44 studies, including 2 053 patients(2 600 eyes)with NDR and 1 775 healthy control patients(2 117 eyes), were included. The Meta-analysis was performed on 17 indexes including the area and perimeters of the foveal avascular zone(FAZ), the vascular density(VD)of FAZ-300um(FD300), acircularity index(AI), VD of macular area, ganglion cell complex(GCC)thickness and retinal nerve fiber layer(RNFL)thickness. Meta-analysis results showed that the area and perimeter of FAZ in superficial capillary plexus(SCP)and deep capillary plexus(DCP)in the NDR group were higher than those of healthy control patients, and FD300, VD of macular area and RNFL thickness were all lower than those in the control group(all P<0.05); The AI values in the NDR group were slightly higher than those in the normal control group, and the GCC thickness and VD of peri-optic papillary were lower than those in the control group, but there was no differences between the groups(P>0.05).CONCLUSIONS: Compared to the healthy control group, NDR patients had increased FAZ area and perimetry, decreased VD of macular area and RNFL thickness and early retinal microvascular damage and neurodegenerative lesions. OCTA could be used as an auxiliary tool for early diagnosis of DR.

Mice ; Animals ; Alzheimer Disease/complications* ; Entorhinal Cortex/metabolism* ; Brain-Derived Neurotrophic Factor/metabolism* ; Memory Disorders/etiology* ; Thalamus/metabolism* ; Disease Models, Animal

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.
COVID-19 ; Cohort Studies ; Contact Tracing ; Humans ; Incidence ; Prospective Studies