Synthesis and performance of ZnO quantum dots water-based fluorescent ink for anti-counterfeiting applications.

In this study, the ZnO quantum dots (QDs) water-based fluorescent anti-counterfeiting ink was prepared with the polyvinylpyrrolidone (PVP) content of 0.15-0.17 g/mL, the ZnO QDs concentration of 4% and water as the solvent, which has good fluorescence, printability and resistance. According to the halftone technology, fluorescence quenching of the ZnO QDs by acid, and acid resistance of the organic fluorescent ink, a high-quality anti-counterfeiting method of fluorescent discoloration was proposed. The QDs ink has broad application prospects in the field of anti-counterfeiting green packaging.

Effect of circulating tumor cells combined with negative enrichment and CD45-FISH identification in diagnosis, therapy monitoring and prognosis of primary lung cancer.

Circulating tumor cells (CTCs) are valuable for diagnosis, monitoring therapy and prognosis in primary lung cancer. Herein, we evaluated the clinical significance of lung cancer CTCs in this study. Detection of CTCs was performed using epithelial cell adhesion molecule-independent enrichment and CD45 fluorescence in situ hybridization detection. CTCs ≥ 2/3.2 mL were considered as positive. The positive rates in primary lung cancer, benign lung disease and healthy control groups were 84, 0 and 4.2 %. CTCs count was significantly higher in lung cancer patients than healthy controls and benign lung disease, with an area under ROC curve of 0.917 (95 % confidence interval 0.855-0.979; p = 0.000) between lung cancer and nonmalignant diseases. CTCs count significantly increased with an increase in pathological stage with mean count of 2.3 ± 2.6 (stage I-II), 3.5 ± 3.3 (stage III) and 4.5 ± 4.3 (stage IV), respectively. The positive detection rate of CTCs for primary lung cancer diagnosis was higher than serum tumor markers. In total, 25 metastasis lung cancer patients participated in the follow-up. Changes in CTCs count after two cycles of chemotherapy were consistent with radiographic appearance. Moreover, CTCs count was better than serum tumor markers for monitoring chemotherapy response. Median progression-free survival (PFS) was 2.05, 3.25 and 8.348 months (p < 0.05) in group in which post-treatment CTCs count was increased, unchanged and decreased, respectively. Furthermore, PFS in patients whose post-treatment CTCs count increased or were unchanged accompanied by a baseline CTCs count ≥3 was significantly shorter than those whose post-treatment CTCs count decreased or was unchanged accompanied with baseline value C < 3 (1.85 vs. 8.22 months, p = 0.000) [Corrected]. Therefore, CTCs are a reproducible indicator of disease status that may be superior to imaging.

[Curative effect of a comprehensive interventional treatment modality on hepatocellular carcinoma complicated with main branch portal vein tumor thrombosis].

OBJECTIVE: To explore the therapeutic efficacy of a combined treatment modality using transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) to treat hepatocellular carcinoma (HCC) complicated with main branch intraportal vein tumor thrombosis (PVTT). METHODS: Clinical data was collected retrospectively for patients diagnosed with and treated for HCC plus main branch PVTT at our hospital between January 2007 and January 2010. The total study population (n = 51) consisted of 38 males and 13 females, with an average of 50.1 years (range: 24-73). Among these patients, 26 had been treated with TACE + PEI (group A) and 25 had been treated with TACE alone (group B). Short-term changes in PVTT (i.e. disappearance, shrinkage, and/or stability) and tumor (i.e. complete response, partial response, and/or stable disease) were assessed by using the t-test (continuous variables) or the Chi-squared or Fisher's exact tests (categorical variables). Between-group differences in survival time were assessed by the Kaplan-Meier analysis and log-rank test. RESULTS: The follow-up time ranged from 3-24 months after treatment, and no serious treatment-related complications were recorded for any of the patients (0/51). The time of TACE treatment was significantly longer for the patients receiving the combination therapy (group A: 3.21.4 vs. group B: 2.40.9, t = 2.22, P = 0.032). The patients in group A received between 2-8 PEI treatments. The TACE + PEI combined treatment showed significantly better therapeutic efficacy for PVTT (group A: 19/26 vs. group B: 10/25, X2 = 5.685, P = 0.019). The tumor response was significantly better in patients treated with TACE + PEI at post-treatment month 3 (group A: 20/26 vs. group B: 18/25, X2 = 0.163, P = 0.705) and month 6 (group A: 17/20 vs. 10/19, X2 = 2.58, P = 0.027). Finally, the average survival time was significantly better in patients treated with TACE + PEI (group A: 12.856.02 months (range: 5-23) vs. group B: 8.653.39 months (range: 4-16), t = 3.051, P = 0.004). CONCLUSION: TACE + PEI combination therapy for main branch PVTT in HCC patients is more efficacious than TACE alone, and is associated with a longer survival time.

[Early prediction of acute kidney injury in infants and young children after cardiopulmonary bypass surgery].

OBJECTIVE: To understand the incidence of acute kidney injury (AKI) in infants and toddlers and evaluate the possibility of predicting AKI with urine neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), N-acetyl-beta-D-glucosaminidase (NAG), microalbumin (MA) and α1-microglobulin (α1-MG) after surgeries for congenital heart diseases with cardiopulmonary bypass (CPB). METHOD: Fifty-eight children (ages ≤ 3 years) who had undergone surgery for congenital heart diseases with CPB were enrolled. Urinary samples were collected before and 4 h, 6 h, 12 h, 24 h post CPB to detect the concentration of NGAL, IL-18, NAG, MA and α1-MG. RESULT: The AKI group had 29 cases, none AKI group also had 29 cases. Urinary concentration of NGAL 4, 6, and 12 h post CPB were significantly higher in AKI group (2820 µg/g, 905.7 µg/g, 76.1 µg/g separately) than in none AKI group (27.6 µg/g, 19.5 µg/g, 16.0 µg/g separately, P < 0.01). Urinary concentration of IL-18 4, 6, 12 and 24 h post CPB were significantly higher in AKI group than in none AKI group (P < 0.05). Urinary concentration of NAG 4 h and 6 h post CPB were significantly higher in AKI group than in none AKI group (P < 0.01). Urinary concentration of MA/UCr post CPB 4 h, 6 h and 12 h were significantly higher in AKI group than in none AKI group (P < 0.05). Urinary concentration of α1-MG/UCr post CPB 4 h, 6 h and 12 h were significantly higher in AKI group than in none AKI group (P < 0.01). All the five biomarkers had predictive abilities at 4-hour after surgery. CONCLUSION: Urine biomarkers NGAL, IL-18, NAG, MA and α1-MG were valuable early predictors of AKI after CPB surgery.

Elevated serum cystatin C is an independent predictor of cardiovascular events in people with relatively normal renal function.

BACKGROUND: Serum level of cystatin C could predict morbidity and mortality for cardiovascular disease in patients with coronary heart disease. However, the predictive value of cystatin C for cardiovascular events in subjects with relatively normal renal function, especially in Asian populations, has rarely been investigated. The current study investigated the relationship between cystatin C and cardiovascular events in a community-based population in Beijing. METHODS: Residents (n=724) with relatively normal renal function (estimated glomerular filtration rate [eGFR] =60 ml/min per 1.73 m2), who attended a community hospital in an urban district of Beijing, were recruited in the study. Risk factors for cardiovascular events were analyzed. RESULTS: Compared with subjects without cardiovascular events, those with cardiovascular events were older (p<0.000001) and had a higher proportion of males (p<0.01), those with diabetes (p<0.05) and smokers (p<0.05). Subjects with cardiovascular events had lower levels of serum high-density lipoprotein cholesterol (HDL-C) and eGFR than those without (p<0.05, p<0.01, respectively). The serum level of cystatin C was significantly higher in subjects with cardiovascular events than in subjects without cardiovascular events (p<0.01). Multivariable logistic regression analysis showed that the independent predictors of cardiovascular events were age, hypertension and serum level of cystatin C (higher than 0.88 mg/L). CONCLUSIONS: Besides the traditional risk factors, a higher level of serum cystatin C might be another independent risk factor for cardiovascular events, even in those with relatively normal renal function.

Trueness investigation of routine creatinine assays on nine homogeneous systems in Beijing demonstrates an encouraging outcome that meets clinical requirements.

BACKGROUND: Serum creatinine (Scr) measurement plays a key role in glomerular filtration rate estimation (eGFR), chronic kidney disease (CKD) diagnosis as well as CKD treatment. However, the test results of Scr from different laboratories vary significantly. In order to get comparable results, the European in vitro diagnostic (IVD) directive requires traceability to reference methods and materials. The purpose of this study was to verify the effect of traceability implementation by investigating the trueness of creatinine measurement on nine homogenous systems in Beijing. METHODS: Commutable frozen human serum reference material, National Institute of Standards & Technology (NIST) Standard Reference Material (SRM) 967, was used to verify the trueness of Scr measurement results from nine homogeneous analytical systems of seven companies which are the most widely used systems in Beijing's third-grade hospitals. The methods referred to the Jaffe's and Enzymatic methods. RESULTS: from nine routine measurement systems were assessed using two criteria: biological variability and Clinical Laboratory Improvement Amendments' 88 (CLIA' 88). We simulated a series of broken lines representing the limits of SD and bias that would produce a relative increase (or decrease) of 10% and 20% in the measurement error when estimating GFR (MEeGFR) using the isotope dilution mass spectrometry (IDMS)-traceable Modification of Diet in Renal Disease (MDRD) Study equation. RESULTS: of the College of American Pathologists (CAP) 2008-B LN24 Survey were compared with our investigation results. RESULTS: Compared with the total error criteria of biological variability, Ortho (traceable to IDMS) met the minimum acceptable criteria; Roche (Jaffe), Roche (Enzymatic), Shino and Daiichi met the desirable criteria at level I. At level II, Ortho (traceable to gas chromatography/isotope dilution mass spectrometry, GC/IDMS), Dade Behring and Beckman (traceable to rate Jaffe) met the minimum acceptable criteria; Roche (Enzymatic) met the optimum criteria. The other five systems met the desirable criteria. Compared with the second criterion, all the results met the requirement of CLIA' 88. Trueness evaluation showed: the MEeGFR of Dade Behring exceeded 10% while the MEeGFRs of Beckman (traceable to rate Jaffe), Beckman (traceable to IDMS) and Ortho (traceable to Jaffe/High Performance Liquid Chromatography) exceeded 20% at level I. At level II the MEeGFRs of Dade Behring, Ortho (traceable to GC/IDMS) and Beckman (traceable to rate Jaffe) exceeded 10%. None of the nine systems got a MEeGFR higher than 20%. The conclusions of NIST SRM 967 agreed with those of LN 24 except for the Beckman measurement system. CONCLUSIONS: Trueness investigation of routine creatinine assays on nine homogeneous systems demonstrates an encouraging outcome that meets clinical requirements. Among the nine homogeneous routine systems, Roche and Daiichi produce the most accurate results. The implementation of traceability is effective.

Diagnostic accuracy of various glomerular filtration rates estimating equations in patients with chronic kidney disease and diabetes.

BACKGROUND: The equations for estimating glomerular filtration rate (GFR) based on creatinine have been found to have limitations and have not been generalizable across all populations. Equations based on cystatin C provide an alternative method to estimate GFR. Whether the equation based on cystatin C alone or combined creatinine would improve GFR estimates has not been validated among Chinese patients with chronic kidney disease (CKD) and diabetes. The aim of this study was to compare the performance of the modification of diet in renal disease (MDRD) equation based on creatinine with the five cystatin C-based formulae for estimation of GFR in patients with CKD and diabetes. METHODS: A total of 166 patients with CKD and 91 patients with type 2 diabetes were enrolled in this study. Cystatin C was measured by using the particle-enhanced immunonephelometric method and estimated formulae proposed by five different investigator teams (Stevens, Ma, Rule, Macisaac and Perkins). The plasma clearance of (99m)Tc-DTPA was determined as measured GFR (mGFR). RESULTS: For CKD patients, the bias and accuracy for the Ma and Macisaac equations were superior compared with the MDRD, and the mean results for the Ma formula were closer to mGFR than the other equations in CKD stages 2 - 5. The differences between Macisaac and mGFR in CKD stages 2 - 4 were significantly less than those in CKD stage 1 or 5. Stevens and Rule's formulae revealed a similar bias and accuracy compared with the MDRD equation. The MDRD formula had a higher accuracy in CKD stages 3 - 5 as compared with the results in other stages. For diabetic patients, the mean results between Macisaac and mGFR were closer than those of other equations in mGFR >or= 90 mlxmin(-1)x1.73 m(-2) stage. In GFR 60 - 89 mlxmin(-1)x1.73 m(-2) stage, the MDRD formula showed the smallest difference compared with other equations. All equations overestimated GFR in the cases with GFR < 60 mlxmin(-1)x1.73 m(-2) stages. The MDRD formula had a greater accuracy within 50% of mGFR than the equations based on cystatin C in diabetic patients. Perkins formula showed a large positive bias and low accuracy, therefore it may not be suitable for assessing GFR in patients with CKD and diabetes. CONCLUSIONS: The formulae for estimating GFR based on cystatin C or creatinine have different trends and accuracies in patients with CKD and diabetes, especially in patients with various GFR levels. The equations based on cystatin C provide less accurate results than MDRD formulae, at least in the diabetic patients. Therefore, whether the formulae based on cystatin C are superior to MDRD formula requires further investigation in large diverse populations.

4-[4-(Piperidin-1-yl)piperidin-1-yl]benzonitrile.

In the title compound, C(17)H(23)N(3), both piperidine rings adopt chair conformations. In the crystal packing, intermolecular C-H⋯N hydrogen bonds and C-H⋯π interactions are present.

Modified glomerular filtration rate estimating equation for Chinese patients with chronic kidney disease.

The Modification of Diet in Renal Disease (MDRD) equations provide a rapid method of assessing GFR in patients with chronic kidney disease (CKD). However, previous research indicated that modification of these equations is necessary for application in Chinese patients with CKD. The objective of this study was to modify MDRD equations on the basis of the data from the Chinese CKD population and compare the diagnostic performance of the modified MDRD equations with that of the original MDRD equations across CKD stages in a multicenter, cross-sectional study of GFR estimation from plasma creatinine, demographic data, and clinical characteristics. A total of 684 adult patients with CKD, from nine geographic regions of China were selected. A random sample of 454 of these patients were included in the training sample set, and the remaining 230 patients were included in the testing sample set. With the use of the dual plasma sampling (99m)Tc-DTPA plasma clearance method as a reference for GFR measurement, the original MDRD equations were modified by two methods: First, by adding a racial factor for Chinese in the original MDRD equations, and, second, by applying multiple linear regression to the training sample and modifying the coefficient that is associated with each variable in the original MDRD equations and then validating in the testing sample and comparing it with the original MDRD equations. All modified MDRD equations showed significant performance improvement in bias, precision, and accuracy compared with the original MDRD equations, and the percentage of estimated GFR that did not deviate >30% from the reference GFR was >75%. The modified MDRD equations that were based on the Chinese patients with CKD offered significant advantages in different CKD stages and could be applied in clinical practice, at least in Chinese patients with CKD.

[Significance of serum carnitine in patients with liver diseases].

OBJECTIVE: To determine serum carnitine levels in patients with liver diseases and to investigate their significance. METHODS: 25 patients with acute viral hepatitis, 34 with chronic viral hepatitis, 22 with post hepatitis cirrhosis with normal renal function, 9 with post hepatitis cirrhosis but with renal disfunction, and 40 healthy subjects (serving as controls) were enrolled in this study. An enzymatic cycling method was used to determine the serum free carnitine levels. RESULTS: The serum free carnitine level was (48.3+/-10.2)micromol/L in the healthy control group. It was (35.2+/-13.2)micromol/L in the acute viral hepatitis group, (36.5+/-9.9)micromol/L in the chronic viral hepatitis group, (45.0+/-11.0)micromol/L in the post hepatitis cirrhosis with normal renal function group, and (83.6+/-50.4)micromol/L in the post hepatitis cirrhosis with renal dysfunction group. Serum free carnitine levels in the acute viral hepatitis and chronic viral hepatitis groups were significantly lower than those in the healthy controls. There were no significant differences in serum free carnitine levels of the post hepatitis cirrhosis group and the normal control group. CONCLUSIONS: Patients with liver diseases can have carnitine metabolism errors. One of the secondary carnitine lack causes is liver disease.

[The application of glomerular filtration rate estimation equations in different stages of chronic kidney disease].

OBJECTIVE: To understand the applicability of MDRD equation in Chinese patients with chronic kidney disease (CKD). Glomerular filtration rate (GFR) estimated with MDRD equation, abbreviated MDRD equation and Cockcroft-Gault equation was compared with (99m)Tc-DTPA plasma clearance by dual plasma sampling method in different stages of CKD. METHODS: CKD were diagnosed according to K/DOQI guideline.298 patients with CKD were selected. Patients'sex, age, height and body weight were recorded and plasma creatinine, urea nitrogen and albumin were measured in a single clinical laboratory. (99m)Tc-DTPA plasma clearance was calculated and standardized by body surface area (sGFR). GFRs estimated with MDRD equation 7, abbreviated MDRD equation and Cockcroft-Gault equation (7GFR, aGFR and cGFR) were compared with sGFR in different stages of CKD. RESULTS: There were 165 male and 133 female in the selected 298 patients with CKD;the average age was (52.5 +/- 15.5) years. There was significant difference between the GFRs of the 3 equations with sGFR in different stages of CKD (P < 0.001). 7GFR, aGFR and cGFR were significantly higher than sGFR in CKD stages 5-4; the lower the sGFR, the more the differences. 7GFR, aGFR and cGFR were significantly lower than sGFR in CKD stage 2-1; the higher the sGFR, the more the differences. CONCLUSION: Our results showed that in Chinese population with CKD, MDRD equation 7, abbreviated MDRD equation and Cockcroft-Gault equation overestimate actual GFR in CKD stages 4-5 and underestimate GFR in CKD stages 1-2. These results indicate that MDRD equation and its modifications for estimation of GFR should be amended when applying to Chinese patients with CKD in clinical practice.

[Isolation and identification of Comamonas testosteroni: cloning and overexpression of 3alpha-hydroxysteroid dehydrogenase in E.coli].

OBJECTIVE: To isolate and identify 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) producing Comamonas testosteroni from soil, and to clone and overexpress 3alpha-HSD in E.coli. METHODS: Samples of pond mud were inoculated into cultural medium with androsterone as sole carbon source. The primary identification was performed according to the morphological observation, biochemical reaction and cultural characterization. To further identify the bacteria, a couple of primers were designed according to the 3alpha-HSD gene of Comamonas testosteroni. An 800 bp fragment containing 3alpha-HSD gene was obtained by PCR amplification. Then the PCR products were inserted into plasmids pET-15b to construct recombinant plasmids pET-15b. Afterwards the host bacteria containing recombinant plasmids pET-15b with proper orientation grew with isopropyl-beta-D-thioglactopyranoside (IPTG) induction. RESULTS: The isolated bacteria which could use androsterone as the sole carbon source had 85% consistency with Comamonas testosteroni. After 5 hours of IPTG induction, a recombinant protein about 29 x10(3) with enzyme activity was overexpressed in the host bacteria E.coli. BL21(DE3) pLysS. This protein could catalyze the dehydrogenization reaction of androsterone (3alpha-hydroxysteroid). CONCLUSION: A strain of Gramjnegative 3alpha-HSD producing Comamonas testosteroni was isolated from pond mud, and recombinant 3alpha-HSD with enzyme activity was overexpressed in E.coli. This work laid good foundation for the purification of recombinant 3alpha-HSD by metal chelate chromatography, and also for the construction of an enzymatic cycling method to measure serum total bile acids with recombinant 3alpha-HSD as the tool enzyme.

Application of GFR-estimating equations in Chinese patients with chronic kidney disease.

BACKGROUND: To evaluate whether the Modification of Diet in Renal Disease (MDRD) equations could be applied accurately to Chinese patients with chronic kidney disease (CKD), glomerular filtration rates (GFRs) estimated by using MDRD equation 7 (7GFR), the abbreviated MDRD equation (aGFR), and the Cockcroft-Gault equation (cGFR) were compared in patients with different stages of CKD. METHODS: The study enrolled patients with CKD diagnosed according to the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines. All patients were older than 18 years and without acute renal function deterioration, edema, skeletal muscle atrophy, or amputation. Sex, age, body height, and body weight were recorded, and plasma creatinine levels were measured by means of Jaffe's kinetic method using a Hitachi 7600 analyzer (Hitachi, Tokyo, Japan; reagents from Roche Diagnostics, Mannheim, Germany). Creatinine, urea, and albumin were measured in a single clinical laboratory. Dual plasma sampling of technetium Tc 99m-labeled diethylene triamine pentaacetic acid plasma clearance was used as the reference standard GFR (sGFR) for comparison of 7GFRs, aGFRs, and cGFRs at different stages of CKD. RESULTS: The study enrolled 261 patients, including 146 men and 115 women. Causes of CKD included primary or secondary glomerular disease, obstructive kidney disease, chronic tubulointerstitial disease, and others. Values for 7GFR, aGFR, and cGFR were significantly greater than for sGFR in patients with CKD stages 4 to 5 (the lower the sGFR, the greater the difference); whereas 7GFR, aGFR, and cGFR were significantly lower than sGFR in patients with CKD stage 1. CONCLUSION: Our results show that in a Chinese population with CKD, MDRD equation 7 and the abbreviated MDRD equation overestimated GFR in patients with CKD stages 4 to 5 and underestimated GFR in those with CKD stage 1. These results indicate that careful modification of these equations may be necessary in Chinese populations with CKD.

Protein-to-creatinine ratio in spot urine samples as a predictor of quantitation of proteinuria.

BACKGROUND: Normal individuals usually excrete very small amounts of protein in the urine. Persistently increased protein excretion is usually a marker of kidney damage. Quantifying protein in urine is commonly used in the diagnosis of kidney diseases, detection of treatment effects and evaluation of prognosis. We evaluated the use of the total protein-to-creatinine ratio (P/C) in spot urine specimens as a predictor of urine protein excretion in 24-h collections. METHODS: The correlation between P/C in first morning and random urine specimens and urinary protein excretion in 24-h collections were analyzed. The cutoff value of P/C in first morning urine specimens for screening urinary protein excretion of 1 and 3 g in 24-h collections was determined by receiver operating characteristics (ROC) curve. RESULTS: For patients with Ccr 10 ml/min, the correlation was highly significant. Similar results were obtained for random urine specimens. By ROC curve analysis, the P/C of 0.94 and 2.84 g/gcr in first morning urine specimens represent the best threshold to detect urine protein excretion of 1 and 3 g in 24-h collections, respectively. There is a good correlation between P/C in first morning urine specimens and random urine specimens from inpatients and outpatients. But the P/C in random specimens is significantly higher than that in first morning specimens in outpatients. CONCLUSION: The P/C in spot urine samples could be used as an alternative to urine protein excretion in 24-h collections in patients with Ccr>10 ml/min. The P/C in first morning urine samples is better than that in random specimens, especially for outpatients.

Detection of antibodies against SARS-CoV in serum from SARS-infected donors with ELISA and Western blot.

Recombinant fragments of S proteins from the Severe Acute Respiratory Syndrome (SARS) coronavirus (SARA-CoV) were generated and used in a Western blot (WB) assay that was compared to a commercial SARS ELISA method. In 85% of confirmed SARS cases (n = 20), the S2 recombinant fragment based WB was positive and this was comparable to the commercial ELISA using heat killed SARS-CoV. WB using the other four recombinant fragments in confirmed SARS cases generated lower rates of detection (S1--75%, S1-N--25%, S1-C--55%). Evaluation of sera from healthy controls (n = 60) resulted in two weakly positive ELISA results with the remainder being negative while the S2 protein WB demonstrated three positive results from the 20 controls with a history of SARS contact and no positive results in 40 noncontact controls. A discrepancy between the ELISA and S2 WB arose when evaluating per-2003 sera from individuals (n = 10) with SARS-like symptoms (ELISA--100% positive, S2 WB--30% positive). These data suggest that the S2 WB assay may be particularly useful in ELISA-negative SARS cases and in some ELISA-positive non-SARS cases.

[The cloning, expression, purification and identification of SARS virus S2 gene and study on its immunological characteristics].

AIM: To express S2 protein of SARS virus fused with Trx and then detect its reactivity to the sera from convalescent SARS patients. METHODS: The Trx-S2 fusion protein was expressed in E.coli. After purification, the Trx-S2 fusion protein was detected by Western blot with 6 serum samples of convalescent SARS patients and 6 serum samples of healthy donors. RESULTS: According to the SDS-PAGE analysis, the relative molecular mass (M(r)) of the Trx-S2 fusion protein is about 76 x 10(3). The fusion protein could react with all the sera from convalescent SARS patients but not with the sera from healthy donors. CONCLUSION: The Trx-S2 fusion protein provides a basis for the research on its role in the course of SARS virus infection of host cells and preparation of recombinant vaccine against SARS virus.

[Expression and purification of recombinant N-terminal protein of SARS S1 subunit expressed in E. Coli].

OBJECTIVE: To express and purify the recombinant N-terminal protein of SARS virus S1 subunit and to study its role in SARS immune response. METHODS: The gene encoding N-terminal 334 amino acid residuals of SARS virus S1 subunit was cloned and expressed in E. Coli. After purification, the recombinant protein was identified by anti-SARS positive sera from recovered SARS patients. The sera from health donors, which were collected before the out-break of SARS, were used as negative control in the study. RESULTS: Sequencing analysis confirmed that the desired DNA sequence in recombinant plasmid was correct and had the same sequence of natural N-terminal of SARS virus S1 subunit. The molecular weight of recombinant fusion protein is about 64 000. The recombinant S1 protein could react with three antibody positive samples from recovered SARS patients, which showed specific bands at 64 000, but not with the control samples according to results of western blot. CONCLUSION: The recombinant N-terminal protein of SARS virus S1 subunit displays specific reaction with SARS antibody and may provide a good tool for further research of immune response to SARS virus.

[Inhibitory effect on proliferation of KG1a cell line by methyltransferase inhibitors].

To explore the possibility of a new therapeutic strategy for leukemia by intervening in the DNA methylation to re-express p15 suppressor gene, methylation inhibitors, 5-Aza-2'-deoxycytidine (5-Aza-CdR) and cell differentiation agent (CDAII) were used to treat myelogenous leukemia cell line KG1a in which p15 gene expression was suppressed due to DNA hypermethylation. The biological characteristics of KG1a cells untreated or treated with the agents were investigated and analyzed using morphology, methylation specific-PCR (MSP), (3)H-labeled microassay technique, restriction endonuclease reaction, flow cytometry and immunofluorescence methods. The results indicated that both agents showed concentration-dependent and time-dependent inhibition of cell proliferation. 5-Aza-CdR and CDAII induced apoptosis and cell differentiation with G(2) and G(0)/G(1) arrest respectively. Furthermore, DNA methyltransferase activity and level of methylation in genomic DNA were decreased and p15 protein was re-expressed partially. It is concluded that it is possible to treat leukemia by intervening in the DNA methylation using methyltransferase inhibitors and it is worth to make a thorough study on mechanism of the new strategy.