Kinetic model analysis is a useful tool for understanding the regulation and control of cellular metabolism and thus offering a guideline for rational design of high efficiency cell factory. Based on previously published models and experimental measurement of enzyme kinetics data, we developed a kinetic model for the threonine biosynthesis pathway in Escherichia coli. This model integrates the central pathways that produce precursors, ATP and reducing power with the threonine biosynthesis pathway from aspartate. In contrast to the previous models, we considered the energy and reducing power balance rather than artificially set their concentrations. Metabolic control analysis of the model showed that enzymes PTS, G6PDH, HDH etc. have great flux control coefficients on the threonine biosynthesis flux. This indicates higher threonine synthesis flux could be achieved by overexpressing these enzymes.
Escherichia coli ; metabolism ; Industrial Microbiology ; Kinetics ; Metabolic Networks and Pathways ; Models, Biological ; Threonine ; biosynthesis

Objectives To analyze the incidence of cranial nerve injury in patients after receiving carotid endarterectomy ( CEA) in a single-center and to investigate its correlation with surgical experiences. Methods The clinical data of patients underwent CEA at Beijing Xuanwu Hospital, Capital Medical University from January. 2001 to December 2013 were analyzed retrospectively. Cranial nerve injury was assessed at day 7 after procedure according to the clinical symptoms,and they were followed up at 1,3,6, and 12 months. The incidence of permanent cranial nerve injury was evaluated. The incidences of permanent cranial nerve injury were further analyzed at two time periods ( from January 2001 to September 2011 and from October 2011 to December 2013 ) . Results ( 1 ) A total of 598 consecutive patients treated with CEA were enrolled,and 15 (2. 5%) of them had cranial nerve injury,including 2 (0. 3%) facial nerve injury,7 (1. 2%) hypoglossal nerve injury,and 6 (1. 0%) vagus nerve injury. Only 1 case (0. 2%) did not recover completely at 6 months after procedure. ( 2 ) The patients with cranial nerve injury were 10 (3. 2%,10/308) and 5 (1. 7%,5/290) respectively from January 2001 to September 2011 and from October 2011 to December 2013). There was no significant difference (P < 0. 05). Conclusion The incidence of cranial nerve injury was low after CEA,and most patients could recover completely. The increased surgical experiences did not show the reduction of cranial nerve injury rate evidently after CEA.

Objective To evaluate the terminal segment of the intracranial vertebral artery (tICVA) fine and atherosclerotic lesions using high-resolution MRI (HRMRI) in order to guide endovascular interventional therapy.Methods From October 2015 to October 2016,4 patients with bilateral tICVA diagnosed with digital subtraction angiography (DSA) and admitted to Xuanwu Hospital,Capital Medical University were analyzed retrospectively.At the same time,time of flight (TOF) and black blood imaging were used.The bilateral tICVA imaging features in 4 patients were analyzed.Congenital dysplasia of vertebral artery and atherosclerotic lesions were identified.Results DSA revealed that bilateral tICVA fine or occlusion.HRMRI evaluation of the vascular wall structure showed that vascular dysplasia in 4 cases were all located on the right sides,showing no obvious thickening of the wall thickness,and the diameter was less than 1/2 of the contralateral side.One patient had atherosclerotic stenosis on the left and 3 had occlusion,showing local wall thickening,plaque formation,and resulting in the narrowing of the corresponding lumen and even occlusion.Three of the patients were treated with endovascular intervention.Conclusion HRMRI is helpful to differentiate hypoplasia in terminal intracranial vertebral artery and atherosclerotic stenosis or occlusion,identifying the dominant side of the vertebral artery and providing image basis for endovascular treatment of vertebral artery.

Objective: To investigate the apoptosis-inducing effect of arsenic trioxide (As2O3) on gastric carcinoma cell line AGS in vitro and to assess the influence of As2O3 on the expression of signal transducers and activators of transcription 3 (STAT3) and vascular endothelial growth factor (VEGF). Methods: AGS cells were treated with different concentrations of As2O3 (1, 5, and 10 ?mol/L) for 24,48, and 72 h. The cell proliferation was detected by MTT assay, cell apoptosis and cell cycle distribution were measured by flow cytometry and TUNEL, and the expression of STAT3 and VEGF was investigated by ELISA, immunohistochemistry and real-time PCR. Results: (1) As2O3 inhibited AGS cell proliferation in a time- and dose-dependent manner; (2) FCM results showed a typical sub-diploid peak before G0/ G1 phase and cell cycle analysis showed G2/M phase arrest; (3) TUNEL analysis revealed the DNA fragmentation; (4) During the As2O3-induced apoptosis of AGS cells, the expression of STAT3 and VEGF was down-regulated, especially when As2O3 was at 10 mol/L. Conclusion: As2O3 can inhibit the proliferation of AGS cells and induce AGS cell apoptosis, which might be related with cell cycle block and down-regulation of STAT3 and VEGF expression.

Objective To evaluate the imaging changes of the arterial wall and lumen at the site of intracranial large artery lesions with high-resolution magnetic resonance imaging (HR-MRI) before and after Wingspan stent implantation.Methods From December 2013 to December 2014,9 patients with symptomatic intracranial arterial stenosis (stenosis rate:70%-99%) admitted to the Department of Interventional Neuroradiology,Xuanwu Hospital,Capital Medical University were enrolled retrospectively.The sites of the lesions included middle cerebral arteries,basilar artery,and intracranial segment of vertebral artery.Head 3D HR-MRI technique was used to analyze and compare the changes of the tube-wall enhancement areas in the lesion sites through image registration and matching.The consistency of stenosis rates measured by HR-MRI and DSA was compared through Pearson correlation analysis and Bland-Altman Plot.Results The success rate of technique was 100% without related complications.(1) After Wingspan stent implantation,the gadolinium enhancement in the vascular walls of the stenosis sites was decreased significantly compared with that before procedure.The area of enhancement decreased was 87±16% after stent implantation compared with before implantation,and the difference was statistically significant (t=2.325,P=0.049).(2) Before stent implantation,the mean stenosis rates of the HR-MRI and DSA measurements were 82±6% and 82±8% respectively,and the difference was not statistically significant (t=0.051,P=0.961);after procedure,the mean stenosis rates of HR-MRI and DSA measurements were 16±12% and 21±12% respectively,and the difference was not statistically significant (t=1.345,P=0.216).(3) The Pearson correlation coefficients of HR-MRI and DSA for stenosis rate measurement before and after stent implantation were 0.347 (P=0.361) and 0.545 (P=0.129) respectively.Bland-Altman statistical images showed that most of the data points were within the consistency limit (x-±1.96 s).Conclusions As an in vivo noninvasive imaging means,HR-MRI can be used to assess the changes of vascular walls of the lesion sites,the vascular lumen,and the original plaques after the intracranial stent release.It can also be used to evaluate the reconstruction of intracranial arterial walls.

Objective To investigate the feasibility and safety of endovascular recanalization of chronic occlusion of large intracranial artery.Methods From January 2009 to January 2017,the clinical and imaging data of 15 patients with chronic occlusion of large intracranial artery admitted to the Department of Interventional Neuroradiology,Xuanwu Hospital,Capital Medical University for endovascular recanalization were analyzed retrospectively.Twelve patients were V4 segment occlusion of vertebral artery and 3 were internal carotid artery occlusion.Preoperative whole brain digital subtraction angiography (DSA) was used to assess the occlusion length and location.High-resolution magnetic resonance imaging (MRI) was used to evaluate the nature of occlusion and the feasibility of recanalization.The intraoperative bilateral femoral artery sheath placement was conducted in 13 cases,one side was used for recanalization and stenting,and the other side was compensated by filling the distal occlusion of the artery through collateral circulation as the reference path map,and increased the feasibility of recanalization.According to the thrombolysis in cerebral infarction (TICI) grades after procedure,the forward flow after recanalization was systematically evaluated,and grade ≥2b was defined as the success of recanalization.Results The median time between the first onset of symptoms and recanalization was 50 (range,18-365) days.The occluded recanalization sites included intracranial segment of vertebral artery in 12 cases and intracranial segment of internal carotid artery in 3 cases.Recanalization was successful in 13 cases and recanalization failure of the intracranial segment of vertebral artery was in 2 cases.Recanalization was successful in 13 cases,and intracranial vertebral artery recanalization failed in 2 cases.Of the 13 patients of successful recanalization,the forward flow of angiography returned to grade TICI 3 in 12 cases after recanalization,and returned to TICI 2b in 1 case;the symptoms of 7 cases were improved,the symptoms of 4 cases did not have any change,and the symptoms of 2 patients aggravated after procedure and developed transient ischemic attack or stroke.After 11 patients were followed up for a median of 39 (3-89) months,the median mRS score was 1 (0-2).Conclusion For recanalization of chronic large intracranial artery occlusion,using preoperative high-resolution magnetic resonance imaging evaluation and intraoperative bilateral sheath placement technique may increase the patency rate and reduce the perioperative complications.

Objective: To explore the false-negative possibility in genetic test of congenital long QT syndrome (LQTS) by next-generation sequencing (NGS). Methods: A total of 28 genomic DNA samples were collected from 4 laboratories including 2 commercial medical laboratories using HiSeq2000 platform as Lab1,n=6 and Lab2,n=8; 1 commercial research service laboratory using Ion-torrent platform as Lab3,n=8 and 1 academic laboratory using HiSeq2000 platform as Lab 4,n=6. Sequencing coverage in the exons of protein-coding region in 3 main LQTS pathogenic genes as KCNQ1, KCNH2, SCN5A and possible pathogenic variants were quantitatively analyzed. Results: In Lab1, Lab 2 and Lab 4 with HiSeq2000 platform, above 98% protein coding regions in 3 pathogenic genes were covered with>10-fold reads and 90%-95% were covered with>30-fold reads. In 2 commercial medical laboratories, 3.63% and 9.84% protein coding regions of KCNQ1 gene in 14 samples were covered with<10-fold reads and with<30-fold reads; lower than 10-fold covering region was focused in the 1st exon including about 2% known or likely pathogenic variants. In 2 commercial medical laboratories, 2.64% and 15.76% protein coding regions of KCNH2 gene in 14 samples were covered with<10-fold reads and with<30-fold reads; low covering region was located in multiple exons. For the data from Lab 1, as high as 28.56% protein coding regions of KCNH2 gene were covered with<30-fold reads including 113 (19.79%) known or likely pathogenic variants. SCN5A gene had the best coverage of protein coding region, with no<10-fold reads in all 4 Labs and no<30-fold reads in 2 commercial medical laboratories. Conclusion: Currently, NGS has low coverage region in both KCNQ1 and KCNH2 genes, pathogenic variants could be missed and false-negative possibility should be highly alert.

Aim To observe the physical coupling between transient receptor potential channel vanilloid type 4 (TRPV4 ) and cPLA2 in endothelial cells. Methods We investigated the physical association of TRPV4-cPLA2 coupling by immunofluorescence reso-nance energy transfer (immuno-FRET)to assess the spatial proximity between TRPV4 and cPLA2 in human microvascular endothelial cells (HMEC),primary cul-tured endothelial cells and in thoracic aortas rings from high salt-induced hypertension mice.Results At the cellular level,with high salt treatment,the physical in-teraction of TRPV4 and cPLA2 was significantly en-hanced in primary vascular endothelial cells and HMEC.Furthermore, in thoracic aortas rings from high salt-induced hypertension mice,we found an in-creases interaction between TRPV4 and cPLA2 in en-dothelial cells from arterial segments .Conclusion High-salt treatment increases the endothelial TRPV4-cPLA2 coupling,indicating that this coupling may pro-vide a new target for vascular endothelial dysfunction.

Objective:To investigate the association between age and cardiac tamponade after radiofrequency ablation of atrial fibrillation(RAAF).Methods:Clinical data of patients undergone de novo AF ablation procedures at Beijing Anzhen Hospital from January 2013 to December 2016 were retrospectively collected.Patients were divided into an elderly group(age ≥60 years)and a non-elderly group(age <60 years). Logistic regression analyses were used to evaluate the association between old age and the risk of cardiac tamponade complicating RAAF.Results:A total of 5 313 patients were involved in this study, including 41 patients(0.77%)with cardiac tamponade.The proportion of cardiac tamponade was higher in the elderly group than in the non-elderly group(1.1% or 32/2 950 vs.0.4% or 9/2 363, χ2=8.489, P=0.004). One patient with cardiac tamponade in the elderly group required immediate surgical repair whereas none in the non-elderly group did.No patient died in hospital.Multivariate Logistic regression analysis showed that the risk of cardiac tamponade increased in the elderly group, compared with the non-elderly group( OR=2.570, 95% CI: 1.190-5.570, P=0.017). Stratified analysis revealed that among females and patients with oral anticoagulants, left atrium dimension < 40 mm or procedure duration≥ 120 min in the elderly group carried a higher risk of cardiac tamponade than those in the non-elderly group( OR=1.011, 2.914, 3.922 and 3.244, P<0.05). Conclusions:Old age(age ≥60 years)is an independent risk factor for cardiac tamponade complicating RAAF.