Thymidine is a commercially useful precursor for production of antiviral compounds such as stavudine and azidothymidine. Biosynthesis of thymidine by Escherichia coli BL21 (DE3) was studied using metabolic engineering methods. The deoA, tdk and udp of the salvage pathway were disrupted from E. coli BL21 to construct BS03 that produced 21.6 mg thymidine per liter. Additional deletion of pgi and pyrL increased the supply of thymidine precursors and the resulting strain BS05 produced 90.5 mg thymidine/L. At last, ushA, thyA, dut, ndk, nrdA and nrdB of thymidine biosynthetic pathway were overexpressed, and the resulting strain BS08 produced 272 mg thymidine/L. In fed-batch fermentation, BS08 accumulated 1248.8 mg thymidine/L. Metabolically engineered strain E. coli has potential applications for thymidine production.
Biosynthetic Pathways ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Industrial Microbiology ; Metabolic Engineering ; Thymidine ; biosynthesis

Objective To investigate the effects of Bifidobacterium infatn ison the expression of in -testinal corticotropin releasing factor ( CRF) receptors and how the peripheral CRF receptors activate mast cells in a murine model of irritable bowel syndrome (IBS).Methods Thirty BALB/c male mice were ran-domly divided into three groups including control group , model group and Bifidobacterium infantis group. The mouse model of IBS was established by using chronic restraint stress .Mice in Bifidobacterium infantis group received daily intragastrical administration of Bifidobacterium infantis for 14 days.Mice in control and model groups were treated with equal volume of saline .Then all mice were killed after the assessment of weight and abdominal withdrawal reflex ( AWR) .The levels of histamine , tryptase and tumor necrosis fac-tor-α( TNF-α) in serum samples were detected by ELISA .The expression of CRF in colonic mucosa was analyzed by immunohistochemistry .The expression of CRF-R1 and CRF-R2 in mast cells and the number of mast cells in colonic mucosa were detected by double immunofluorescence staining assay .The expression of CRF-R1 and CRF-R2 at mRNA level in colon were detected by reverse transcription polymerase chain reac-tion ( RT-PCR) .Results Compared with control group , the levels of histamine , tryptase and TNF-αin pe-ripheral blood samples , the expression of CRF-R1 and CRF-R2 at mRNA level , and the number of mast cells, CRF-R1+mast cells and CRF-R2+mast cells in colonic mucosa were increased significantly in model group (P<0.05), but were remarkably down-regulated with the treatment ofB ifidobacterium infantis (P<0.05).Conclusion Bifidobacterium infantis could reduce the activation of mast cells in a murine model of IBS by inhibiting the expression of CRF-R1 and CRF-R2 in intestinal mast cells .

Objective To explore what cause the screw loosening after the internal fixation with thoracic and lumbar pedicle screws in the elderly and to develop the preventive measures.Methods Retrospective analysis were used to collect the clinical data from patients ager 60 years and over who had undergone surgeries of thoracolumbar pedicle screw internal fixation in our hospital during May 2011 and May 2013.Totally 187 cases were included in this study.According to whether there was a loosening of the screws, patients were divided into fixtion-loose and-well groups.The operation time and blood loss volume in the two groups were recorded.Visual analogue scale (VAS), Oswestry disability index (ODI), the rate of screw loosening were compared at 6 months after operation and the last follow-up.The causes of screw loosening were analyzed.Results The main causes for the thoracic and lumbar pedicle screw internal fixation were thoracolumbar kyphoscoliosis, fractures,spondylolisthesis, cancer and degenerative diseases, etc.Patients were followed up for an average of (35.2±8.7) months.13 patients (7.0％) were found screw loosening, 5 males and 8 females, with the mean age of (78.4 ± 3.5) years.The screw loosening occurred 3 months to 1 year after the surgery, (7.6±3.7) months on average.Among the 13 patients with screw loosening, 1 patient suffered screw loosening in single segment, 3 patients in two segments, and 9 patients in three segments or above.Osteoporosis combined with screw loosening.appeared in 10 patients VAS and ODI scores in all subjects had statistically differences at 6 months after operation and the last follow up versus preoperation (P＜0.05 for all), but no statistical difference versus the last follow-up(P＞ 0.05).There were significant differences in gender and preoperative osteoporosis rate between the two groups (P＜0.05 for both).Conclusions Osteoporosis is one of the reasons for the screw loosening in elderly patients after pedicle screw internal fixation.The increased probability of the screw loosening in long segment may be related with the change of the older spine mechanics.Further randomized controlled trials are still required to confirm whether elderly osteoporosis patients need to receive bone cement augmentation treatment.

Objective:To study whether Noxa mediates cell death induced by etoposide in the human neuroblastoma(NB)cells.Methods:NB cells(TB3 and TB8) were treated with different concentrations of etoposide(0, 0.125, 0.25, 0.5 0.75, 1.0 mg/L), and the cell survival was detected by CCK8 assay.After treated with etoposide, NB cells were collected at different time points, then total RNAs were isolated and RT-qPCR was performed to detect the mRNA expression of Noxa.At the same time, the whole cell lysates were extracted and western blot was performed to detect the protein expression of Noxa.In order to evaluated the effect of Noxa on etoposide-induced cell survival, Noxa siRNA was transfected into NB cells, then CCK8 assay was performed.Results:After treatment with different concentrations of etoposide(0.125 mg/L、0.25 mg/L、0.5 mg/L、0.75 mg/L、1.0 mg/L ), the survival rates of TB3 cells were(73.13±8.45)%, (56.18±10.50)%, (33.90±4.17)%, (26.76±6.67)%, (13.49±0.58)%, respectively(compared with the control group, P<0.01); the survival rates of TB8 cells were(71.06±6.96)%, (37.45±0.68)%, (25.53±3.70)%, (20.28±2.75)%, (10.09±2.52)%, respectively(compared with the control group, P<0.01).The mRNA and protein expression of Noxa in NB cells were both increased in a time-dependent manner after treated with etoposide.The siRNA of Noxa could reduce the expression of Noxa in TB3 and TB8 cells after transfection.Treated with etoposide 0.5 mg/L, cell survival rates of TB3 cells tranfected with control siRNA, Noxa siRNA1, Noxa siRNA2 were(45.12±13.58)%, (72.70±21.34)%, (52.08±20.36)%, respectively; cell survival rates of TB8 were(35.52±0.38)%, (63.94±0.10)%, (50.27±1.62)%, respectively(compared with the control group, P<0.01); Treated with etoposide 1.0 mg/L, cell survival rates of TB3 cells tranfected with control siRNA, Noxa siRNA1, Noxa siRNA2 were(13.26±1.84)%, (51.08±2.41)%, (42.80±1.42)%, respectively(compared with the control group, P<0.05); cell survival rates of TB8 were(22.22±3.39)%, (58.00±11.37)%, (40.55±6.94)%, respectively(compared with the control group, P<0.05). Conclusion:Pro-apoptotic molecular Noxa mediated the Etoposide-induced cell death in NB cells(TB3 and TB8) in time and concentration-dependent manner.

Abstract Long noncoding RNA (lncRNA) is closely related to the pathogenesis of cancer,representing a burgeoning field in tumor research in recent years. MAGI2-AS3, a tumor-associated lncRNA, exerts pivotal roles in epigenetics, transcription and post-transcriptional regulation. Studies have suggested that MAGI2-AS3 may be involved in multiple stages of tumor development, and has potential applications for tumor diagnosis, therapy and prognosis. This review summarizes the expression, regulatory mechanism and clinical application value of MAGI2-AS3 in common malignant tumrs, providing the reference for tumor prevention and treatment.

There are still differences in the surgical treatment of children with pulmonary atresia(PA-VSD) with ventricular septal defect. The high rate of postoperative complications and reoperation intervention is still a problem that plagues surgeons. There are few reports on the understanding of the anatomy and physiological functions of MAPCAs. This article systematically reviews and analyzes domestic and foreign literature, and reviews the anatomical classification, surgical management strategies and related complications of PA-VSD patients.

Objective To investigate the utility of diffusion weighted imaging (DWI) and blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) in the assessment of renal hypoxia in an experimental model of mice with lupus nephritis (LN).Methods MRL/lpr mice (n=13) were studied and C57BL/6 mice (n=10) served as controls.Urinary albumin to creatinine ratio (ACR),serum creatinine (Scr),anti-ds-DNA antibody,and complement C3 levels were measured.The mice underwent coronal echo-planar DWI and BOLD MRI of the kidneys when they were 14-16 weeks old.Hypoxyprobe was administered intraperitoneally to the mice 1 hour before they were sacrificed.The distribution of HypoxyprobeTM-1,hypoxia-inducible factor 1 α (HIF-1 o) and heme oxygenase-1 (HO-1) in renal tissues was detected by immunohistochemical analysis and Western blotting.Results Urinary ACR,Scr and anti-ds-DNA antibody levels in MRL/lpr mice were significantly higher than that in C57BL/6 mice.It was found that HypoxyprobeTM-1,HIF-1o and HO-1 distributed widely in the renal tissue of MRL/lpr mice,and closely associated with the renal tubulointerstitial lesion.The mean apparent diffusion coefficient (ADC) value of kidneys in MRL/lpr mice was (1.52±0.27) × 10-3 mm2/s,and the mean R2* values of the renal cortex and medulla were (30.95 ±4.59)/s and (23.43± 3.06)/s respectively,all significantly lower than that in C57BL/6 mice (P=0.037,P=0.030 and P=0.043,respectively).The ADC of medulla was negatively correlated with urinary albumin to creatinine ratio (r=-0.364,P=0.032;r=-0.329,P=0.050),the ADC of cortex was negatively correlated with the level of serum creatinine (r=-0.814,P=0.014;r=-0.755,P=0.031) when b value was 500 s/mm2 and 800 s/mm2,and the mean R2* value was negatively correlated with the degree of tubulointerstitial lesions and the expression of hypoxia parameters (all P ＜ 0.05).Conclusions Renal hypoxia may play an important role in renal tubulointerstitial lesion.Functional MRI may be used to monitor renal function changes,pathological injuries and renal hypoxia in LN.

Objective To analyze the roles and mechanisms of lactitol and Bifidobacterium infantis in the treatment of rat constipation and to investigate their effects on aquaporin3 (AQP3) and interstitial cells of Cajal (ICC) in colon tissues.Methods Thirty SD male rats were recruited in this study,6 of which were randomly selected as the control and the rest were given 4 mg/kg.d of loperamide for 5 consecutive days to construct the rat model of constipation.The rats with constipation were randomly divided into four groups including model group,lactitol treatment group,Bifidobacterium infantis treatment group and lactitol in combination with Bifidobacterium infantis treatment group.General indexes including food intake,water intake,body weight,fecal water content and intestinal transit rate of each rat were measured after receiving corresponding treatments for 7 consecutive days.The levels of substance P (SP) and vasoactive intestinal peptide (VIP) in serums samples were detected by ELISA.The expression of protein kinase A (PKA) and neurokinin-1 receptor (NK-1) at mRNA level in colon tissues were detected by real-time polymerase chain reaction (real-time PCR).Western blot assay and real-time PCR analysis were used to detect the expression of AQP3 and c-kit at protein and mRNA levels,respectively.Results Compared with the rats in model group,the levels of fecal water content and intestinal transit rate,the concentrations of SP and VIP in serums samples,the expression of PKA and NK-1 at mRNA level and the expression of AQP3 and c-kit at mRNA and protein levels were significantly increased in rats from the three treatment groups (P＜0.05).The most effective treatment was lactitol in combination with Bifidobacterium infantis,followed by the lactitol treatment and then the Bifidobacterium infantis treatment.Conclusion The combination therapy with lactitol and Bifidobacterium infantis increased the serum levels of SP and VIP in rats with constipation.SP could enhance the contraction of gastrointestinal smooth muscles and improve the intestinal motility by binding to the NK-1 receptor on the membrane of ICC.VIP could promote the absorption of water in intestinal tracts,soften stools and alleviate constipation by upregulating the expression of AQP3 at both protein and mRNA levels via the cyclic adenosine monophosphate-PKA (cAMP-PKA) signaling pathway.

Objective To investigate the effects of two cholesterol-lowering probiotics, DM9054 (Lac-tobacillus Rhamnosus GG, LGG) in combination with 86066 (Lactobacillus plantarum WCFS1, LP), on the metabolism of bile acid via a rat model of non-alcoholic fatty liver disease (NAFLD) and the possible mecha-nism. Methods Twenty-one SD male rats were randomly divided into three groups including control group, NAFLD model group and probiotics intervention group. Rats in the control group received normal diet. The rat model of NAFLD was established by feeding rats with chronic high fat diet (45% of calories derived from fat di-et) for 20 weeks. Rats in the probiotics intervention group were given high fat diet together with cholesterol-low-ering probiotics through oral gavage. General indexes of each group including body weight and the levels of tri-glyceride, cholesterol and CK18-M30 in serums samples were detected. The expression of cholesterol 7-alpha hydroxy-lase (CYP7A1), fibroblast growth factor receptor 4 (FGFR4), farnesoid X receptor (FXR), fibroblast grwoth factor 15 (FGF15) and apical sodium-dependent bile acid transparter(ASBT) at mRNA level were de-tected by using real-time polymerase chain reaction (real-time PCR). Western blot assay was used to detect the protein expression of CYP7A1, FXR in liver tissues and ASBT in ileum tissues. The expression of FXR in liver and ileum tissues were analyzed by immunohistochemistry. Results Rats with NAFLD showed loss of body weight and decreased levels of the serological markers after treating with the probiotics (P<0. 05). Compared with the rats in model group, enhanced expression of CYP7A1 and inhibited expression of FXR in liver tissues, activated FXR-FGF15 pathway in ileum tissues as well as down-regulated expression of ASBT in ileum tissues were detected in rats receiving probiotics intervention (P<0. 05). No significant difference in the expression of FGFR4 at mRNA level was observed between NAFLD rats with or without probiotics intervention (P>0. 05). Conclusion Probiotics intervention might up-regulate the expression of CYP7A1 by suppressing the FXR path-way in liver tissues and inhibiting the expression of ASBT in ileum tissues. Treating NAFLD rats with cholester-ol-lowering probiotics could activate the FXR-FGF15 pathway in ileum tissues and enhance the metabolism of bile acid, which contributed to the alleviation of NAFLD.

Objective To explore the effect of narrative therapy on family environment and values in adolescents with emotional disorder.Methods 35 adolescents with emotional disorder and their parents from Affiliated Brain Hospital,Nanjing Medical University were enrolled and treated by narrative therapy.Family environment was assessed using Family Environment Scale-Chinese Version (FES-CV)and was compared between pre-and posttherapy.Results 28 adolescents with emotional disorder and their parents completed therapy.The cohesion,independence,intellectual orientation,active-recreation orientation and organization in FES-CV showed higher scores at post-therapy than at pre-therapy ((6.89 ± 2.56) vs.(4.21 ± 3.21) ; (5.54 ± 1.35) vs.(4.68 ± 1.51) ;(4.75±2.07)vs.(3.50±2.12);(4.07±2.65)vs.(2.50±2.32);(3.68±1.77)vs.(2.50±1.62)respectively).The contradict in FES-CV showed lower scores at post-therapy than at pre-therapy ((2.75 ± 2.44) vs (5.25 ± 2.50)).The values of adolescents with emotional disorder and their parents had a positive change after narrative therapy.Conclusion Narrative therapy is effective on the positive change of FES-CV and values of adolescents with emotional disorder and their parents.