ABSTRACT
BACKGROUND: Prophylactic cranial irradiation (PCI) is part of standard care in limited-stage small cell lung cancer (SCLC) at present. As evidence from retrospective studies increases, the benefits of PCI for limited-stage SCLC are being challenged. METHODS: A multicenter, prospective, randomized controlled study was designed. The key inclusion criteria were: histologically or cytologically confirmed small cell carcinoma, age ≥ 18 years, KPS ≥ 80, limited-stage is defined as tumor confined to one side of the chest including ipsilateral hilar, bilateral mediastinum and supraclavicular lymph nodes, patients have received definitive thoracic radiotherapy (regardless of the dose-fractionation of radiotherapy used) and chemotherapy, evaluated as complete remission (CR) of tumor 4-6 weeks after the completion of chemo-radiotherapy. Eligible patients will be randomly assigned to two arms: (1) PCI and brain MRI surveillance arm, receiving PCI (2.5 Gy qd to a total dose of 25 Gy in two weeks) followed by brain MRI surveillance once every three months for two years; (2) brain MRI surveillance alone arm, undergoing brain MRI surveillance once every three months for two years. The primary objective is to compare the 2-year brain metastasis-free survival (BMFS) rates between the two arms. Secondary objectives include 2-year overall survival (OS) rates, intra-cranial failure patterns, 2-year progression-free survival rates and neurotoxicity. In case of brain metastasis (BM) detect during follow-up, stereotactic radiosurgery (SRS) will be recommended if patients meet the eligibility criteria. DISCUSSION: Based on our post-hoc analysis of a prospective study, we hypothesize that in limited-stage SCLC patients with CR after definitive chemoradiotherapy, and ruling out of BM by MRI, it would be feasible to use brain MRI surveillance and omit PCI in these patients. If BM is detected during follow-up, treatment with SRS or whole brain radiotherapy does not appear to have a detrimental effect on OS. Additionally, this approach may reduce potential neurotoxicity associated with PCI.
Subject(s)
Brain Neoplasms , Lung Neoplasms , Small Cell Lung Carcinoma , Humans , Adolescent , Small Cell Lung Carcinoma/diagnostic imaging , Small Cell Lung Carcinoma/therapy , Lung Neoplasms/diagnostic imaging , Lung Neoplasms/therapy , Prospective Studies , Retrospective Studies , Magnetic Resonance Imaging , Brain Neoplasms/therapy , Brain Neoplasms/prevention & control , Chemoradiotherapy/adverse effects , Cranial Irradiation/adverse effects , Pathologic Complete Response , Brain/pathologyABSTRACT
Elemental analysis of aluminum alloy samples with calibration-free laser-induced breakdown spectroscopy (CF-LIBS) encounters two difficulties: the inconvenience of determining accurate temperature and electron density of the plasma and the influence of self-absorption of the observed aluminum lines. To solve this problem, target-enhanced orthogonal double-pulse laser-induced breakdown spectroscopy in the reheating regime combined with the one-point calibration method was proposed in this work. A mixture of copper powders and K H C O 3 grains was pressed to a pellet and used as the target. Accurate determination of plasma temperature and electron density can be obtained using a reference target. The plasma temperature could be determined with Saha-Boltzmann plot of copper, and the electron density of the plasma could be determined according to the Stark broadening of the H α line of hydrogen. Aluminum alloy samples were analyzed with a relative error of better than 0.02% for a major element. This approach provides a convenient way to determine the temperature and electron density of the plasma more accurately and is able to reduce the influence of self-absorption, which is helpful for realizing quantitative elemental analysis of different samples while using a calibration-free algorithm.
ABSTRACT
An open quantum system operated at the spectral singularities where dimensionality reduces, known as exceptional points (EPs), demonstrates distinguishing behavior from the Hermitian counterpart. Here, we present an analytical description of local density of states (LDOS) for microcavity featuring chiral EPs, and unveil the anomalous spontaneous emission dynamics from a quantum emitter (QE) due to the non-Lorentzian response of EPs. Specifically, we reveal that a squared Lorentzian term of LDOS contributed by chiral EPs can destructively interfere with the linear Lorentzian profile, resulting in the null Purcell enhancement to a QE with special transition frequency, which we call EP induced transparency. While for the case of constructive interference, the squared Lorentzian term can narrow the linewidth of Rabi splitting even below that of bare components, and thus significantly suppresses the decay of Rabi oscillation. Interestingly, we further find that an open microcavity with chiral EPs supports atom-photon bound states for population trapping and decay suppression in long-time dynamics. As applications, we demonstrate the advantages of microcavity operated at chiral EPs in achieving high-fidelity entanglement generation and high-efficiency single-photon generation. Our work unveils the exotic cavity quantum electrodynamics unique to chiral EPs, which opens the door for controlling light-matter interaction at the quantum level through non-Hermiticity, and holds great potential in building high-performance quantum-optics devices.
ABSTRACT
Biosensors have various potential applications in biomedical research and clinical diagnostic, especially in detection of biomolecules in highly diluted solutions. In this study, a high-performance Bloch surface wave biosensor was constructed for the detection of hemoglobin. The procedure consisted of designing a porous silicon-based Kretschmann configuration to ensure excitation of the Bloch surface wave. The performance of the resulting sensor was then optimized by adjusting the buffer layer parameters based on the impedance matching method. The results showed an increase in the quality factor and figure of merit of the biosensor as a function of the decrease in thickness and refractive index of the buffer layer. The combination of the two optimization methods resulted in the quality factor and figure of merit of the optimized biosensor reaching as high as Q = 6967.4 and FOM = 11050RIU-1, respectively. In sum, the designed biosensor with high performance looks promising for future detection of hemoglobin.
Subject(s)
Biosensing Techniques , Silicon , Silicon/chemistry , Porosity , Biosensing Techniques/methods , Refractometry , HemoglobinsABSTRACT
The Fano effect arising from the interference between two dissipation channels of the radiation continuum enables tuning of the photon statistics. Understanding the role of the Fano effect and exploiting it to achieve strong photon correlations are of both fundamental and applied significance. We present an analytical description of Fano-enhanced photon correlations based on cavity quantum electrodynamics to show that the Fano effect in atom-cavity systems can improve the degree of antibunching by over four orders of magnitude. The enhancement factors and the optimal conditions are explicitly given, and found to relate to the Fano parameter q. Remarkably, the Fano enhancement manifests robustness against the decoherence processes and can survive in the weak coupling regime. We expect our work to provide insight to tuning the photon statistics through the Fano effect, which offers a new, to the best of our knowledge, route to enhance the photon correlations, as well as the possibility of generating nonclassical light in a wider diversity of systems without the need of a strong light-matter interaction.
ABSTRACT
In this work, we report the application of a calibration-free (CF) method combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) to the analysis of a silver alloy. The sample was ablated by a fiber laser operated at a 30 kHz pulse repetition rate, and a spark discharge was applied to enhance plasma emission. Electron number density and plasma temperature were estimated using Stark broadening of spectral lines and the Saha-Boltzmann plot method, respectively. The fulfillment of the local thermodynamic equilibrium (LTE) approximation of the measurement was verified. Averaged electron density and plasma temperature were calculated as 1.11×1017cm-3 and 7355 K, respectively. The elemental composition of a silver alloy sample was determined, and the result was compared with that analyzed with inductively coupled plasma optical emission spectrometry (ICP-OES). The analytical error was within a 15% range. It was demonstrated that the CF HRR LA-SIBS technique could potentially provide elemental analysis for silver alloys without requiring a standard sample.
ABSTRACT
Fiber optic high repetition rate laser-ablation spark-induced breakdown spectroscopy was applied to realize elemental analysis of aluminum alloys. A compact fiber laser was used as source of laser-ablation and spark discharge was used to enhance the atomic emission of the laser-induced plasma. Plasma emission spectra were recorded with a compact fiber spectrometer in a nongated signal recording mode. Calibration curves of Cr, Cu, Mn, Mg, and Zn in aluminum alloys were built under appropriate experimental conditions and the detection limits of these elements were determined to be 4.4, 5.6, 4.9, 8.3, and 31.1 ppm, respectively. Compared to those obtained in fiber optic high repetition rate laser-induced breakdown spectroscopy using the same fiber laser, a 3-18 improvement factor in the detection limit has been demonstrated. This system is compact and cost effective, and the technique can be applied to rapid and convenient element analysis of different alloy samples.
ABSTRACT
OBJECTIVE: To analyze the incidence and mortality rates of thyroid cancer (TC) in China from 2008 to 2012. METHODS: Incident and death cases of TC were retrieved from the National Central Cancer Registry (NCCR) database collecting from 135 cancer registries in China during 2008-2012. The crude incidence and mortality rates of TC were calculated by area (urban/rural), region (eastern, middle, western), gender and age group (0, 1-4, 5-9, , 85+). China census in 2000 and world Segi's population were applied for age-standardized rates. Joinpoint (Version 4.6.0.0) model was used for time-trend analysis. RESULTS: The crude incidence rate of TC was 7.56/100,000 which ranked the seventh in overall cancers. The age-standardized incidence rates by China population (ASIRC) and by World population (ASIRW) were 6.25/100,000 and 5.52/100,000, respectively. The crude mortality of TC in China was 0.52/100,000. The age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 0.34/100,000 and 0.32/100,000, respectively. Incidence and mortality rates of TC were higher in females than in males and higher in urban areas than in rural areas. Eastern areas had the highest incidence followed by middle and western areas. TC incidence increased dramatically after age of 15 years, then peaked at 14.08/100,000 in the group of 50-54 years and finally decreased sharply after 55 years old. TC mortality increased with age in population, reaching the peak of 5.09/100,000 in sub-population aged 85 years or older. TC incidence increased by 4.73 times from 2.40/100,000 in 2003 to 13.75/100,000 in 2012 with an average annual increase of 20%, while TC mortality only increased slightly around 0.32/100,000 from 0.26/100,000 to 0.36/100,000. CONCLUSIONS: Appropriate targeted prevention, early detection and treatment programs can be carried out to curb the rapid growth trend of TC and control the disease burden.
ABSTRACT
A study on elemental analysis of alloy samples under low sample destruction with dual-pulse laser-ablation laser induced breakdown spectroscopy (LA-LIBS) based on one picosecond Nd : YAG laser is presented. In LA-LIBS, low pulse energy 532 nm laser was used for sample ablation and high pulse energy, timedelayed 1 064 nm laser was used for re-excitation of the ablated samples to enhance atomic emissions of the laser-induced plasma and signal detection sensitivity. The influence of pulse energies of the ablation laser and excitation laser to the signal intensities was studied experimentally. I was observed that Cu 324.75 nm line intensity in LA-LIBS was enhanced 86 times in comparison with that obtained in SP-LIBS under 10 µJ pulse energy of the ablation laser and 2.5 mJ pulse energy of the excitation laser. The diameter of the crater generated in LA-LIBS was less than 10 µm. It is demonstrated the possibility of using dual-pulse LA-LIBS to realize elemental analysis of solid sample under low sample destruction. This technique is valuable for elemental analysis of precious samples and 2D elements mapping under high spatial resolution.
ABSTRACT
BACKGROUND: Men who have sex with men (MSM) have become one of high-risk population for human immunodeficiency virus (HIV) infection, due to their multiple sex partners and unprotected anal intercourse. Promoting HIV testing is an effective strategy for the prevention and control of HIV infection. We assessed the factors associated with a prior HIV testing history, which could provide guidance for implementation of future HIV intervention programs. METHODS: A cross-sectional study was conducted in three cities of Zhejiang Province, namely, Hangzhou, Ningbo and Wenzhou, using respondent-driven sampling, between December 2013 and June 2014. A face-to-face questionnaire survey was employed to collect relevant information about HIV testing. Univariate and multivariate logistic regression analyses were used to identify the factors associated with a prior HIV testing history. RESULTS: The adjusted rate of prior HIV testing among MSM in Zhejiang Province was 55.9 %. The adjusted rates of HIV and syphilis infections among MSM in Zhejiang Province were 14.0 % and 11.4 %, respectively. A weighted multivariate analysis showed that MSM of older age were more likely to be tested, as were MSM with higher level of education, self-reported homosexuality and a higher frequency of receiving AIDS/sexually transmitted infections educational intervention in the past year. MSM with suicidal inclination and self-perceived lower possibility of HIV infection were less likely to report ever having undergone an HIV test. CONCLUSIONS: The prevalence of prior HIV testing among MSM in Zhejiang Province, China is low. Effective and more frequent interventional measures should be adopted to improve risk awareness and psychosocial support for younger, less educated MSM, and to encourage more MSM to undergo HIV testing.
Subject(s)
HIV Infections/diagnosis , HIV Infections/prevention & control , Health Care Surveys/statistics & numerical data , Homosexuality, Male/statistics & numerical data , Mass Screening/statistics & numerical data , Adolescent , Adult , Aged , China , Cross-Sectional Studies , Humans , Male , Middle Aged , Prevalence , Young AdultABSTRACT
The ability to invade host cells is a key to the survival and pathogenicity of Apicomplexan parasites. Toxoplasma gondii is an obligatory intracellular parasite. Its motility, invasion into, and egression from host cells are powered by a machinery called acto-myosin motor ï¼AMMï¼. The AMM is composed of myosin A, a myosin light chain ï¼MLC1ï¼, two essential light chains ï¼ELCï¼1, 2 and gliding-associated protein ï¼GAPï¼. The GAP family has been discovered to include GAP45, GAP50, GAP80, GAP70 and GAP40, which are the major components of glideosome that provides power for parasite motility. The glideosome of apicomplexan parasites is an actin- and myosin-based power machine located at the pellicle between the plasma membrane ï¼PMï¼ and inner membrane complex (IMC). This review outlines our current understanding of GAP function and architecture as well as the molecular basis for parasite motility. Meanwhile, the use of GAPs as the candidate toxoplasmosis vaccine is prospected.
Subject(s)
Toxoplasma , Actins , Animals , Cell Membrane , Cell Movement , Membrane Proteins , Protozoan ProteinsABSTRACT
Syndecan-1 (Sdc1) and its endo-beta-D-glucuronidase heparanase (HPSE) are implicated in maintenance of intestinal epithelial barrier (IEB), but their alterations and roles in high-glucose/hyperglycaemia (HG) conditions have not been fully investigated. This study aimed to determine the expression pattern, the possible regulation mechanism of Sdc1 and HPSE in HG conditions, and their potential effects on IEB. Therefore, diabetic mice/cell models were developed, and tissue/serum samples, cell lysate and culture supernatants were harvested. The expression of Sdc1 and HPSE in control, HG and designated interventions groups were detected. Phosphorylations of mitogen-activated protein kinase signalling pathway (MAPK), the expressions of Occludin and ZO-1, and the levels of transepithelial electrical resistance (TEER) were measured and monitored. The results showed that in HG conditions, intestinal tissue and cellular Sdc1 were significantly decreased, but the expression of HPSE, and soluble Sdc1 in serum and culture supernatants were remarkably increased. Such alterations of Sdc1 and HPSE were associated with solely p38 MAPK activation, and were correlated with the reductions of Occludin, ZO-1 and TEER. Heparin (Sdc1 analogue) and SB203580 (a p38 MAPK inhibitor), instead of insulin, alleviated Sdc1 destruction and HPSE overexpression, and effectively prevented against the reductions of tight junctions and the abnormality of intestinal permeability in HG conditions. In conclusion, we confirm the unique alterations of Sdc1 and HPSE in HG conditions, and found their interactions with p38 MAPK activation and IEB. These indicate that Sdc1/HPSE modulation can be viewed as an important complementary treatment for relieving HG-induced gastrointestinal damage.
Subject(s)
Epithelial Cells/drug effects , Glucose/pharmacology , Glucuronidase/genetics , Syndecan-1/genetics , Animals , Blotting, Western , Cell Line , Diabetes Mellitus, Experimental/genetics , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/physiopathology , Electric Impedance , Epithelial Cells/metabolism , Epithelial Cells/physiology , Female , Gene Expression/drug effects , Glucose/metabolism , Glucuronidase/metabolism , Hypoglycemic Agents/pharmacology , Insulin/pharmacology , Intestines/cytology , Mice , Microscopy, Fluorescence , Occludin/metabolism , Rats , Reverse Transcriptase Polymerase Chain Reaction , Syndecan-1/metabolism , Zonula Occludens-1 Protein/metabolism , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
BACKGROUND AND PURPOSE: Total homocysteine level (tHcy) is a risk factor of ischemic stroke (IS) and coronary heart disease. However, the results are conflicting and mainly focused on healthy individuals in developed countries. METHODS: A prospective, population-based cohort study was conducted among 5935 participants from 60 communities in the city of Shenzhen, China. A Cox regression analysis was applied to evaluate the contribution of tHcy to the risk of IS and coronary heart disease. The effect of folic acid supplementation on tHcy levels was also evaluated among 501 patients with essential hypertension, who received an average of 2.5 years of folic acid supplementation. RESULTS: After adjustment for confounding factors, the hazard ratios (95% confidence intervals) of IS caused by hyperhomocysteinemia were 2.18 (1.65-2.89), 2.40 (1.56-3.67), and 2.73 (1.83-4.08) in the total, male, and female participants, respectively. Compared with normal levels of tHcy (<15 µmol/L), the hazard ratios (95% confidence intervals) for IS in the highest tHcy category (≥30 µmol/L) were 4.96 (3.03-8.12), 6.11 (3.44-10.85), and 1.84 (0.52-6.46) in the total, males, and females participants, respectively. However, we did not observe a significant relationship between tHcy and the risk of coronary heart disease. The 2.5 years of folic acid supplementation reduced tHcy levels by 6.7 µmol/L (27.92%) in patients with essential hypertension. CONCLUSIONS: Hyperhomocysteinemia in Chinese hypertensive patients is significantly associated with IS risk but not coronary heart disease susceptibility, and folic acid supplementation can efficiently reduce tHcy levels.
Subject(s)
Brain Ischemia/blood , Coronary Disease/blood , Homocysteine/blood , Hypertension/blood , Population Surveillance , Stroke/blood , Adult , Aged , Brain Ischemia/diagnosis , Brain Ischemia/epidemiology , China/epidemiology , Cohort Studies , Coronary Disease/diagnosis , Coronary Disease/epidemiology , Female , Humans , Hypertension/diagnosis , Hypertension/epidemiology , Longitudinal Studies , Male , Middle Aged , Prospective Studies , Risk Factors , Stroke/diagnosis , Stroke/epidemiologyABSTRACT
BACKGROUND: To assess the association between total plasma homocysteine (tHcy) and ischemic stroke (IS) in hypertensive subjects in a matched case-control study. METHODS: This is a 1:2 matched and population-based case-control study, all of the participants were recruited from the 60 communities in Shenzhen, China. Demographic and socioeconomic characteristics, medical records, lifestyle risk factors and other clinical characteristics were obtained from all of the subjects. The association between tHcy and incidence of IS was analyzed by using conditional logistic regression models. RESULTS: The median values of plasma tHcy were significantly higher in IS subjects than in non-IS subjects, especially in women. After adjusted for the confounding factors in Model 2, compared with the lowest quartile of tHcy, the odds ratios (ORs) and 95% CIs of the highest quartile of tHcy for IS were 0.83 (0.36-1.90) in men, 4.51 (1.29-15.7) in women and 1.31 (0.70-2.47) in the total subjects; the ORs and 95% CIs for IS per 5 µmol/L increase in homocysteine were 1.11 (0.99-1.22), 1.25 (1.03-1.58) and 1.15 (1.01-1.28) in men, women and total subjects, respectively. We observed significant associations in crude model, Model 1 and Model 2 in women for the comparison of tHcy ≥ 15 µmol/L versus < 15 µmol/L. Interaction analysis showed that the association of tHcy with IS was significant in women (p-interaction = 0.04). CONCLUSION: This matched case-control study indicates that tHcy may increase the susceptibility to IS in essential hypertension subjects, especially in women. Further large prospective cohort studies are needed to confirm our findings.
Subject(s)
Brain Ischemia/blood , Homocysteine/blood , Hypertension , Stroke , Aged , Case-Control Studies , China/epidemiology , Essential Hypertension , Female , Humans , Hypertension/blood , Hypertension/complications , Hypertension/diagnosis , Hypertension/epidemiology , Incidence , Logistic Models , Male , Middle Aged , Odds Ratio , Prospective Studies , Risk Factors , Stroke/blood , Stroke/epidemiology , Stroke/etiologyABSTRACT
High spectral analysis sensitivity can be achieved with orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy under minimal sample ablation. Therefore, the contradiction between spatial resolution and analytical sensitivity existed in single-pulse laser-induced breakdown spectroscopy can be resolved fundamentally in this technique. In order to eliminate the influence of different experimental parameters to the signal intensities and final results of quantitative analysis, the correlation between copper atomic emission and silver atomic emission was studied experimentally in this technique for silver jewellery samples. It was demonstrated that the intensity of atomic emission of copper at 324.75 nm and that of silver at 328.07 nm was linearly correlated with high correlation coefficient. Therefore, it was possible to eliminate the influence of different experimental parameters, such as geometrical arrangement and pulse energy of the ablation laser to the signal of copper atomic emission by selecting 328.07 nm line of silver as internal standard. A quantitative analysis of copper impurity in silver jewellery can be realized by using orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy. A calibration curve of copper was successfully built based on internal standard method while selecting 328.07 nm line of silver as internal standard. The limit of detection of copper in silver matrix was determined to be 44 ppm in this technique when the crater's diameter was about 17 µm under current experimental condition.
ABSTRACT
Toxoplasma gondii rhoptry protein 2 family (ROP2 family), secreted by the rhoptry, plays an important role in T. gondii invasion of host cells and its virulence. The ROP2 family members include ROP2, ROP4, ROP5, ROP8, ROP13, ROP16, ROP17, and ROP18. Recent studies have found that these members are potential vaccine candidates against toxoplasmosis, and can induce the protective immunity of the host. This paper reviews the research advance on the ROP2 family members as DNA or protein vaccines against toxoplasmosis.
Subject(s)
Toxoplasma , Protozoan Proteins , Protozoan Vaccines , VirulenceABSTRACT
Orthogonal dual-wavelength dual-pulse laser-induced breakdown spectroscopy (ODWDP-LIBS) with 266+1064 nm wavelength combination was applied to realize silver jewelry microanalysis with enhanced sensitivity and minimal sample ablation. In this technique, the 266 nm laser with low pulse energy was selected as ablation laser and the time-delayed 1064 nm laser with moderate pulse energy was selected as reheating laser to enhance plasma emission. Significant signal enhancement was achieved under the excitation of the reheating laser without increasing mass ablation which was only determined by the ablation laser. Internal standard method was applied to realize quantitative analysis of copper impurity in silver jewelry samples. The calibration curve was built, and the limit of detection of copper in silver matrix was determined to be 37.4 ppm when the crater diameter was controlled at 6.5 µm. This technique is especially useful for microanalysis of precious samples due to the property of less sample ablation in comparison with single-pulse laser-induced breakdown spectroscopy (SP-LIBS) under the same analytical sensitivity.
ABSTRACT
Based on the Green function method, the nonlinear Schrödinger equation is directly solved in the time domain (without Fourier transform). Because the dispersion and nonlinear effects are calculated simultaneously, it does not bring any spurious effect such as the split-step method in which the step size has to be carefully controlled by an error estimation. By this time domain solution, the pulse fission is analyzed, and we obtain the relationship between the minimum T0 (the half-width at 1/e-intensity point of a pulse) and dispersion coefficients (ß2, ß3, and ß4). Thus the concrete dispersion values, which have an impact on ultrashort pulses (the quantity units is femtosecond or attosecond), are listed. It has been demonstrated that pulse fission occurs in the normal and anomalous dispersion regimes, even though fourth-order dispersion and the fifth-order nonlinear effects are not taken into account.
ABSTRACT
Uridine phosphorylase (UPP) is a key enzyme of pyrimidine salvage pathways, catalyzing the reversible phosphorolysis of ribosides of uracil to nucleobases and ribose 1-phosphate. UPP plays an important role in the regulation of uridine homeostasis. Although UPP from a variety of organisms have many similarities in their functions, there are differences in many other aspects, such as physical and chemical properties, structure characteristics, active sites, and substrate binding sites. Therefore, UPP has broad application prospects in the design and development of antibacterial, antiparasitic drugs. This article summarizes the physico-chemical property and research progress of UPP from a variety of organisms, in order to integrate information of UPP, provide theoretic basis for further study of Toxoplasma gondii UPP protein as a feasible target antigen for toxoplasmosis vaccination.
Subject(s)
Parasites , Vertebrates , Animals , Catalytic Domain , Ribosemonophosphates , Uracil , Uridine PhosphorylaseABSTRACT
OBJECTIVE: To predict the physicochemical properties and antigenic epitopes of Toxoplasma gondii uridine phosphorylase (TgUPase), clone, and express TgUPase gene, and analyze its immunoreactivity. METHODS: The physical and chemical characters and specific epitopes of TgUPase protein were predicted by bioinformatics software tools. Total RNA was extracted from RH strain T. gondii tachyzoites. A pair of specific primers was designed according to the open reading frame of TgUPase gene (GenBank Accession No. DQ385446.1). RT-PCR product was digested with restriction enzyme and ligated into a pET-30a(+) vector. The recombinant plasmid pET-30a(+)-TgUPase was transformed into E. coli DH5alpha and the positive clones were selected by colony PCR and confirmed by double restriction enzyme digestion and sequencing. The constructed pET-30a(+)-TgUPase was then transformed into E. coli BL21(DE3) and induced with IPTG for expression. The expression product was analyzed through SDS-PAGE followed by Coomassie blue staining. Western blotting assay with His primary antibody and human anti-T. gondii serum was used to confirm the expression of rTgU-Pase and detect its immunoreactivity. RESULTS: Bioinformatics prediction results showed that rTgUPase protein was 303 amino acids in length with a predicted molecular mass of M, 33 042.9, and this soluble protein had three potential T/B cell epitopes. The product of RT-PCR was 921 bp. Colony PCR, double restriction enzyme digestion and DNA sequencing confirmed that the recombinant plasmid pET-30a(+)-TgUPase was constructed. SDS-PAGE showed that bacteria containing recombinant plasmid pET-30a(+)-TgUPase expressed a soluble protein of His-TgUPase (about Mr 38,000) after being induced with IPTG. The recombinant protein reacted positively with His primary antibody and human anti-T. gondii serum by Western blotting analysis. CONCLUSION: The recombinant plasmid pET-30a (+)-TgUPase is constructed and the soluble rTgUPase shows immunoreactivity.