BACKGROUND:Lumbar degenerative disease is a disease of the musculoskeletal system that primarily affects the intervertebral structures,and the disease is treated with lumbar fusion and disc replacement.OBJECTIVE:To conduct comparative analysis of the differences between lumbar fusion,mechanical lumbar disc prosthesis replacement,and viscoelastic lumbar disc prosthesis replacement.METHODS:The computerized tomography images of a healthy adult were used to construct a finite element model of the L2-L5 normal lumbar spine with Mimic,Geomagic,and Ansys software.The equipment required for lumbar fusion and lumbar spine replacement was constructed using modeling software,and the L3-L4 segment of the lumbar spine was processed according to the surgical requirements for lumbar fusion and intervertebral disc replacement,creating the corresponding finite element model.Specific boundary conditions were applied to extract the mobility of each lumbar spine segment,the stresses on the neighboring intervertebral discs,and the stresses on the prosthesis lining.RESULTS AND CONCLUSION:(1)Compared with the preoperative period,the maximum stress in the upper neighboring discs increased by 64.09％and 39.79％in the forward flexion and lateral bending states if the original mobility was maintained after lumbar fusion surgery.The maximum stress in the lower neighboring discs increased by 24.39％and 20.98％in forward flexion and lateral bending.This suggested that the upper adjacent discs would suffer greater stress changes than the lower adjacent discs during heavy physical labor.(2)Disc replacement did not show significant changes in adjacent disc stress,with mechanical prosthesis replacement slightly reducing adjacent disc stress,while viscoelastic prosthesis replacement was more in line with the biological properties of the disc,with maximum adjacent disc stress similar to that of the preoperative period.(3)In terms of stability,the mechanical prosthesis replacement segment showed a 51.67％increase in range of motion in the lateral bending state and a 53.27％increase in range of motion in the posterior extension state,whereas the viscoelastic prosthesis was better able to maintain mobility in the replacement segment.(4)In addition,the stresses in the liner of the mechanical prosthesis were mainly concentrated in the edge region,and this stress distribution may lead to edge wear and thus affect the service life of the prosthesis.

BACKGROUND:Lumbar degenerative disease is a disease of the musculoskeletal system that primarily affects the intervertebral structures,and the disease is treated with lumbar fusion and disc replacement.OBJECTIVE:To conduct comparative analysis of the differences between lumbar fusion,mechanical lumbar disc prosthesis replacement,and viscoelastic lumbar disc prosthesis replacement.METHODS:The computerized tomography images of a healthy adult were used to construct a finite element model of the L2-L5 normal lumbar spine with Mimic,Geomagic,and Ansys software.The equipment required for lumbar fusion and lumbar spine replacement was constructed using modeling software,and the L3-L4 segment of the lumbar spine was processed according to the surgical requirements for lumbar fusion and intervertebral disc replacement,creating the corresponding finite element model.Specific boundary conditions were applied to extract the mobility of each lumbar spine segment,the stresses on the neighboring intervertebral discs,and the stresses on the prosthesis lining.RESULTS AND CONCLUSION:(1)Compared with the preoperative period,the maximum stress in the upper neighboring discs increased by 64.09％and 39.79％in the forward flexion and lateral bending states if the original mobility was maintained after lumbar fusion surgery.The maximum stress in the lower neighboring discs increased by 24.39％and 20.98％in forward flexion and lateral bending.This suggested that the upper adjacent discs would suffer greater stress changes than the lower adjacent discs during heavy physical labor.(2)Disc replacement did not show significant changes in adjacent disc stress,with mechanical prosthesis replacement slightly reducing adjacent disc stress,while viscoelastic prosthesis replacement was more in line with the biological properties of the disc,with maximum adjacent disc stress similar to that of the preoperative period.(3)In terms of stability,the mechanical prosthesis replacement segment showed a 51.67％increase in range of motion in the lateral bending state and a 53.27％increase in range of motion in the posterior extension state,whereas the viscoelastic prosthesis was better able to maintain mobility in the replacement segment.(4)In addition,the stresses in the liner of the mechanical prosthesis were mainly concentrated in the edge region,and this stress distribution may lead to edge wear and thus affect the service life of the prosthesis.

Objective To establish an efficient DNA extraction method for the batch identification of genotypes in model mice.Methods We extracted total DNA from transgenic mouse tails using four methods:alkaline simplified group,alkaline routine group,protease K cleavage group and DNA extraction kit group.The purity and concentration of DNA obtained by the four methods were measured,the effects of gel electrophoresis were evaluated,and the time and experimental costs of the four methods were compared.Results The protease K cleavage method produced the highest concentration of DNA,followed by the simplified alkaline boiling and routine alkaline boiling method.The reagent kit produced the highest DNA purity,followed by the simplified alkaline boiling method.The DNA templates obtained by the four method could be amplified by polymerase chain reaction and gel electrophoresis to obtain clear DNA target bands.In addition,the DNA template extracted by the simplified alkaline boiling method could be used for gene identification after storage at-20℃for 1 month,as well as requiring the least time and lowest costs.Conclusions The simplified alkaline boiling method is currently the simplest,fastest,and most economical DNA template-extraction method for batch identification of genotypes in model mice.

Objective:To investigate the effect of CT-derived fractional flow reserve (CT-FFR) measurement sites on the values and the diagnostic performance, and to determine the optimal measurement site for CT-FFR using invasive FFR as the reference standard.Methods:This study was part of the CT-FFR CHINA clinical trial. Patients with suspected coronary artery disease who were scheduled for invasive coronary angiography (ICA) were prospectively recruited from five clinical centers across the country from November 2018 to March 2020. Each enrolled patient underwent coronary CT angiography (CCTA), CT-FFR, ICA, and invasive pressure wire-based FFR assessments sequentially within one week. Four groups of CT-FFR values were obtained on each enrolled target vessels according to different CT-FFR measurement locations: 1, 2, 3 cm distal to the target lesion, and terminal vessel groups. Spearman and Bland-Altman analyses were used to explore the correlation and consistency of CT-FFR values and FFR values at different measurement sites. The measurement deviation of CT-FFR was also compared. Diagnostic accuracy and performance of CT-FFR, including sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC), in discriminating myocardial ischemia were analyzed across all measurement site groups on a per-vessel level, using FFR as the reference standard.Results:A total of 289 patients with 345 target lesion vessels were included. According to CCTA, there were 51 target vessels (14.8%) with<50% stenosis, 106 vessels (30.7%) with 50%-69% stenosis, and 188 vessels (54.5%) with stenosis≥70%. At per-vessel level, CT-FFR and FFR values at each measurement position group were highly positively correlated: 1 cm distal to target lesion group, r=0.734 ( P<0.001); 2 cm distal to target lesion group, r=0.732 ( P<0.001); 3 cm distal to target lesion group, r=0.737 ( P<0.001); terminal vessel group was 0.719 ( P<0.001). At per-vessel level, CT-FFR and FFR values of all measurement sites were in good agreement (Bland-Altman analysis results): 1 cm distal to target lesion group, 0.014 (95% LoA 0.002-0.026); 2 cm distal to target lesion group, 0.026 (95% LoA 0.015-0.038); 3 cm distal to target lesion group, 0.040 (95% LoA 0.039-0.051); terminal vessel group, 0.075 (95% LoA 0.064-0.087). And at per-vessel level, the accuracy of diagnosing myocardial ischemia with CT-FFR at 1 cm was highest [84.6% (95% CI 80.4%-88.3%)], and the lowest accuracy in the terminal vessel group [67.0% (95% CI 61.7%-72.0%)]. However, there was no significant difference in the diagnostic accuracy of CT-FFR at 1 cm, 2 cm [80.6% (95% CI 76.1%-84.6%)] and 3 cm [77.5% (95% CI 72.6%-81.7%)]. AUC of CT-FFR at 1 cm distal to the lesion were both highest for global level and moderately stenosis (50%-69%) lesions [0.85 (95% CI 0.81-0.89), 0.84 (95% CI 0.77-0.90)]. And the differences were statistically significant among the four measurement location groups (all P<0.05). Conclusions:The deviation of CT-FFR increases with measurement site distance distal to target lesions. One centimeter distal to the target lesion is the optimal measurement site, and the CT-FFR value here shows the highest diagnostic performance for myocardial ischemic lesions, especially for moderate stenosis.

Objective:Investigate the impact of calcification on the long-term outcomes of patients with coronary chronic total occlusion (CTO) after percutaneous coronary intervention (PCI).Methods:A retrospective cohort study was conducted. Patients who underwent PCI and had at least one CTO lesion at Fuwai Hospital between January 2010 and December 2013 were consecutively enrolled. Calcification was evaluated by coronary angiography, and patients were divided into two groups: moderate/severe calcification group and non/mild calcification group. Clinical follow-up was completed up to 5 years. Incidence of PCI-related complications and immediate procedural outcomes were compared between two groups, and the primary endpoint was the target lesion failure (TLF) at 5 years after PCI. Clinical follow-up endpoint events were analyzed using Kaplan-Meier survival analysis with log-rank test, and Cox multivariate regression model was used to evaluate the relationship between calcification and TLF.Results:The study included 2 659 CTO patients with an age of (57.2±10.5) years, of whom 442 (16.6%) were female, and among whom 13.5% (360/2 659) had moderate/severe calcification. Compared with the non/mild calcification group, the moderate/severe calcification group had a higher incidence of PCI-related complications (43.2% (156/361) vs. 32.5% (772/2 374), P<0.001) and procedural failure (34.3% (124/361) vs. 24.3% (577/2 374), P<0.001). Additionally, the moderate/severe calcification group showed a higher risk of the primary endpoint event (TLF) during the 5-year follow-up (19.8% vs. 15.3%, log-rank P=0.028). Higher incidence of cardiac death was observed in moderate/severe calcification group (5.7% vs. 2.7%, log-rank P=0.003). Cox multivariate regression analysis revealed that moderate/severe calcified plaques remained an independent risk factor for 5-year TLF after CTO-PCI ( HR=1.34, 95% CI: 1.01-1.79, P=0.043). Conclusion:Compared with CTO patients with non/mild calcification, those with moderate/severe calcification have higher procedural failure and complication rates, as well as poorer long-term prognosis, mainly due to an increase in cardiac death.

Objectives:Coronary slow flow(CSF)has long been regarded as a marker of coronary microvascular dysfunction(CMD).This study aims to evaluate the diagnostic value of CSF for CMD in patients with angina and nonobstructive coronary arteries(ANOCA).Methods:The study data were derived from the ANOCA-CMD prospective cohort study.All enrolled patients underwent coronary angiography and concurrent coronary physiological assessments in the left anterior descending artery using pressure-wire and thermodilution techniques to obtain coronary flow reserve(CFR)and the index of microcirculatory resistance(IMR).Based on the results,CMD was classified into four subtypes:CMD with elevated IMR(IMR≥25),CMD with reduced CFR(CFR<2.5),CMD with either reduced CFR or elevated IMR(CFR<2.5 or IMR≥25),and CMD with both reduced CFR and elevated IMR(CFR<2.5 and IMR≥25).The corrected thrombolysis in myocardial infarction(TIMI)frame count(CTFC)in the left anterior descending artery was calculated from coronary angiography images,with CSF defined as CTFC>27.This study evaluated the correlation between CTFC,CFR,and IMR,and investigated the diagnostic value of CSF for CMD in ANOCA patients.Results:A total of 103 ANOCA patients were enrolled in this study,with a mean age of(64.2±10.6)years,and 53.4％were female.Among them,57 patients(55.3％)were diagnosed with coronary slow flow.Patients with slow flow had higher IMR(P<0.001)and CFR(P=0.041).Similarly,the proportion of CMD with elevated IMR was higher in the slow flow group(P<0.001),while the proportion of CMD with reduced CFR was lower(P=0.044).There was no significant difference between the groups in the proportions of CMD with either reduced CFR or elevated IMR or CMD with both reduced CFR and elevated IMR(all P>0.05).CTFC was positively correlated with hyperemic mean transit time(r=0.424,P<0.001),IMR(r=0.430,P<0.001),and CFR(r=0.211,P=0.032).The area under the curve(AUC)of CTFC for diagnosing CMD with elevated IMR was 0.721(95％CI:0.623-0.819)with an accuracy of 67％(57％,76％),for diagnosing CMD with reduced CFR was 0.610(95％CI:0.499-0.720)with an accuracy of 60％(50％,70％),for diagnosing CMD with either reduced CFR or elevated IMR was 0.549(95％CI:0.425-0.673)with an accuracy of 47％(37％,57％),and for diagnosing CMD with both reduced CFR and elevated IMR was 0.582(95％CI:0.471-0.693)with an accuracy of 47％(37％,57％).Thus,CSF demonstrated limited diagnostic values across all subtypes of CMD.Conclusions:In ANOCA patients,CSF cannot serve as an effective diagnostic marker for CMD.Therefore,in clinical practice,the slow flow phenomenon should not be directly equated with the presence of coronary microvascular dysfunction in ANOCA patients.

Objective To establish an efficient DNA extraction method for the batch identification of genotypes in model mice.Methods We extracted total DNA from transgenic mouse tails using four methods:alkaline simplified group,alkaline routine group,protease K cleavage group and DNA extraction kit group.The purity and concentration of DNA obtained by the four methods were measured,the effects of gel electrophoresis were evaluated,and the time and experimental costs of the four methods were compared.Results The protease K cleavage method produced the highest concentration of DNA,followed by the simplified alkaline boiling and routine alkaline boiling method.The reagent kit produced the highest DNA purity,followed by the simplified alkaline boiling method.The DNA templates obtained by the four method could be amplified by polymerase chain reaction and gel electrophoresis to obtain clear DNA target bands.In addition,the DNA template extracted by the simplified alkaline boiling method could be used for gene identification after storage at-20℃for 1 month,as well as requiring the least time and lowest costs.Conclusions The simplified alkaline boiling method is currently the simplest,fastest,and most economical DNA template-extraction method for batch identification of genotypes in model mice.

Objectives:Coronary slow flow(CSF)has long been regarded as a marker of coronary microvascular dysfunction(CMD).This study aims to evaluate the diagnostic value of CSF for CMD in patients with angina and nonobstructive coronary arteries(ANOCA).Methods:The study data were derived from the ANOCA-CMD prospective cohort study.All enrolled patients underwent coronary angiography and concurrent coronary physiological assessments in the left anterior descending artery using pressure-wire and thermodilution techniques to obtain coronary flow reserve(CFR)and the index of microcirculatory resistance(IMR).Based on the results,CMD was classified into four subtypes:CMD with elevated IMR(IMR≥25),CMD with reduced CFR(CFR<2.5),CMD with either reduced CFR or elevated IMR(CFR<2.5 or IMR≥25),and CMD with both reduced CFR and elevated IMR(CFR<2.5 and IMR≥25).The corrected thrombolysis in myocardial infarction(TIMI)frame count(CTFC)in the left anterior descending artery was calculated from coronary angiography images,with CSF defined as CTFC>27.This study evaluated the correlation between CTFC,CFR,and IMR,and investigated the diagnostic value of CSF for CMD in ANOCA patients.Results:A total of 103 ANOCA patients were enrolled in this study,with a mean age of(64.2±10.6)years,and 53.4％were female.Among them,57 patients(55.3％)were diagnosed with coronary slow flow.Patients with slow flow had higher IMR(P<0.001)and CFR(P=0.041).Similarly,the proportion of CMD with elevated IMR was higher in the slow flow group(P<0.001),while the proportion of CMD with reduced CFR was lower(P=0.044).There was no significant difference between the groups in the proportions of CMD with either reduced CFR or elevated IMR or CMD with both reduced CFR and elevated IMR(all P>0.05).CTFC was positively correlated with hyperemic mean transit time(r=0.424,P<0.001),IMR(r=0.430,P<0.001),and CFR(r=0.211,P=0.032).The area under the curve(AUC)of CTFC for diagnosing CMD with elevated IMR was 0.721(95％CI:0.623-0.819)with an accuracy of 67％(57％,76％),for diagnosing CMD with reduced CFR was 0.610(95％CI:0.499-0.720)with an accuracy of 60％(50％,70％),for diagnosing CMD with either reduced CFR or elevated IMR was 0.549(95％CI:0.425-0.673)with an accuracy of 47％(37％,57％),and for diagnosing CMD with both reduced CFR and elevated IMR was 0.582(95％CI:0.471-0.693)with an accuracy of 47％(37％,57％).Thus,CSF demonstrated limited diagnostic values across all subtypes of CMD.Conclusions:In ANOCA patients,CSF cannot serve as an effective diagnostic marker for CMD.Therefore,in clinical practice,the slow flow phenomenon should not be directly equated with the presence of coronary microvascular dysfunction in ANOCA patients.

Objective:To investigate the effect of CT-derived fractional flow reserve (CT-FFR) measurement sites on the values and the diagnostic performance, and to determine the optimal measurement site for CT-FFR using invasive FFR as the reference standard.Methods:This study was part of the CT-FFR CHINA clinical trial. Patients with suspected coronary artery disease who were scheduled for invasive coronary angiography (ICA) were prospectively recruited from five clinical centers across the country from November 2018 to March 2020. Each enrolled patient underwent coronary CT angiography (CCTA), CT-FFR, ICA, and invasive pressure wire-based FFR assessments sequentially within one week. Four groups of CT-FFR values were obtained on each enrolled target vessels according to different CT-FFR measurement locations: 1, 2, 3 cm distal to the target lesion, and terminal vessel groups. Spearman and Bland-Altman analyses were used to explore the correlation and consistency of CT-FFR values and FFR values at different measurement sites. The measurement deviation of CT-FFR was also compared. Diagnostic accuracy and performance of CT-FFR, including sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC), in discriminating myocardial ischemia were analyzed across all measurement site groups on a per-vessel level, using FFR as the reference standard.Results:A total of 289 patients with 345 target lesion vessels were included. According to CCTA, there were 51 target vessels (14.8%) with<50% stenosis, 106 vessels (30.7%) with 50%-69% stenosis, and 188 vessels (54.5%) with stenosis≥70%. At per-vessel level, CT-FFR and FFR values at each measurement position group were highly positively correlated: 1 cm distal to target lesion group, r=0.734 ( P<0.001); 2 cm distal to target lesion group, r=0.732 ( P<0.001); 3 cm distal to target lesion group, r=0.737 ( P<0.001); terminal vessel group was 0.719 ( P<0.001). At per-vessel level, CT-FFR and FFR values of all measurement sites were in good agreement (Bland-Altman analysis results): 1 cm distal to target lesion group, 0.014 (95% LoA 0.002-0.026); 2 cm distal to target lesion group, 0.026 (95% LoA 0.015-0.038); 3 cm distal to target lesion group, 0.040 (95% LoA 0.039-0.051); terminal vessel group, 0.075 (95% LoA 0.064-0.087). And at per-vessel level, the accuracy of diagnosing myocardial ischemia with CT-FFR at 1 cm was highest [84.6% (95% CI 80.4%-88.3%)], and the lowest accuracy in the terminal vessel group [67.0% (95% CI 61.7%-72.0%)]. However, there was no significant difference in the diagnostic accuracy of CT-FFR at 1 cm, 2 cm [80.6% (95% CI 76.1%-84.6%)] and 3 cm [77.5% (95% CI 72.6%-81.7%)]. AUC of CT-FFR at 1 cm distal to the lesion were both highest for global level and moderately stenosis (50%-69%) lesions [0.85 (95% CI 0.81-0.89), 0.84 (95% CI 0.77-0.90)]. And the differences were statistically significant among the four measurement location groups (all P<0.05). Conclusions:The deviation of CT-FFR increases with measurement site distance distal to target lesions. One centimeter distal to the target lesion is the optimal measurement site, and the CT-FFR value here shows the highest diagnostic performance for myocardial ischemic lesions, especially for moderate stenosis.

Objective:Investigate the impact of calcification on the long-term outcomes of patients with coronary chronic total occlusion (CTO) after percutaneous coronary intervention (PCI).Methods:A retrospective cohort study was conducted. Patients who underwent PCI and had at least one CTO lesion at Fuwai Hospital between January 2010 and December 2013 were consecutively enrolled. Calcification was evaluated by coronary angiography, and patients were divided into two groups: moderate/severe calcification group and non/mild calcification group. Clinical follow-up was completed up to 5 years. Incidence of PCI-related complications and immediate procedural outcomes were compared between two groups, and the primary endpoint was the target lesion failure (TLF) at 5 years after PCI. Clinical follow-up endpoint events were analyzed using Kaplan-Meier survival analysis with log-rank test, and Cox multivariate regression model was used to evaluate the relationship between calcification and TLF.Results:The study included 2 659 CTO patients with an age of (57.2±10.5) years, of whom 442 (16.6%) were female, and among whom 13.5% (360/2 659) had moderate/severe calcification. Compared with the non/mild calcification group, the moderate/severe calcification group had a higher incidence of PCI-related complications (43.2% (156/361) vs. 32.5% (772/2 374), P<0.001) and procedural failure (34.3% (124/361) vs. 24.3% (577/2 374), P<0.001). Additionally, the moderate/severe calcification group showed a higher risk of the primary endpoint event (TLF) during the 5-year follow-up (19.8% vs. 15.3%, log-rank P=0.028). Higher incidence of cardiac death was observed in moderate/severe calcification group (5.7% vs. 2.7%, log-rank P=0.003). Cox multivariate regression analysis revealed that moderate/severe calcified plaques remained an independent risk factor for 5-year TLF after CTO-PCI ( HR=1.34, 95% CI: 1.01-1.79, P=0.043). Conclusion:Compared with CTO patients with non/mild calcification, those with moderate/severe calcification have higher procedural failure and complication rates, as well as poorer long-term prognosis, mainly due to an increase in cardiac death.