The development of a fluorescence polarization immunoassay for aflatoxin detection.

A fluorescence polarization immunoassay (FPIA) was developed for the analysis ofaflatoxins (AFs) using an anti-aflatoxin B1 (AFB1) monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed an IC50 value of 23.33 ng/mL with a limit of detection of 13.12 ng/mL for AFB1. The cross-reactivities of AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 with the antibody were 100%, 65.7%, 143%, 23.5%, 111.4%, and 2%, respectively. The group-specificity of anti-AFB1mAb indicated that the FPIA could potentially be used in a screening method for the detection of total AFs, albeit not AFG2 and AFM2. The total time required for analyzing 96 samples in one microplate was less than 5 min. This study demonstrates the potential usefulness of the FPIA as a rapid and simple technique for monitoring AFs.

Electroencephalogram analysis: an early diagnostic method for assessing cognitive impairment after cerebral hemorrhage.

Cerebral hemorrhage may cause cognitive dysfunction. Electroencephalogram (EEG) is a noninvasive diagnostic tool for assessment of cerebral function. A total of 174 patients (including cognitively impaired and cognitively normal) with cerebral hemorrhage, and 120 healthy persons (CN), were recruited between August 2008 and July 2012 at the Department of Neurology. EEG was used to analyze cerebral function of patients and normal persons. Correlation, clustering and concordance analyses were performed to analyze the relationship between EEG power and Montreal Cognitive Assessment (MoCA) scores. Cognitively impaired patients had a significantly decreased EEG beta power (0.793 ± 0.176 µV(2)) compared with cognitively normal patients (1.589 ± 0.205 µV(2), P < .01) or healthy persons (1.651 ± 0.185 µV(2), P < .01). Significantly negative correlations between beta power and hemorrhage region, size, amount, and patients' age were apparent (r = -0.91888, -0.78569, -0.84961, and -0.80365, respectively, all Ps < .001). There was good concordance between the K-means clustering algorithm calculating beta power and MoCA scoring (κ = .904, P < .001). In conclusion, the analysis method of EEG (beta power) abnormalities holds considerable promise to assess cognitive impairment after cerebral hemorrhage. Cognitive impairment was negatively correlated to hemorrhage region, size, amount, and age.

Development of a rapid multi-residue assay for detecting ß-lactams using penicillin binding protein 2x*.

OBJECTIVE: To develop a rapid multi-residue assay for detecting 16 demanded by the European Union (EU). METHODS: A recombinant penicillin-binding protein (PBP) 2x* from Streptococcus pneumoniae R6 was expressed in vitro and six ß-lactams were conjugated to HRP by four methods. A rapid multi-residue assay for ß-lactams was established with PBP2x* and HRP-conjugate. RESULTS: PBP2x* was expressed and purified successfully and the ideal HRP-conjugate was identified. The multi-residue assay was developed. After optimization, penicillin G, ampicillin, amoxicillin, cloxacillin, dicloxacillin, oxacillin, nafcillin, cephalexin, ceftiofur, cefalonium, cefquinome, cefazolin, cefoperazone, cephacetrile, and cephapirin can be detected at levels below MRL in milk with simple pretreatment. CONCLUSION: This assay developed can detect all 16 ß-lactams demanded by the European Union (EU). The whole procedure takes only 45 min and can detect 42 samples and the standards with duplicate analysis.

[Effects of 1, 25 (OH)2D3 on bleomycin-induced pulmonary fibrosis in mice].

OBJECTIVE: To observe the effects of 1, 25(OH)2D3 on bleomycin-induced pulmonary fibrosis in mice and to explore its mechanisms. METHODS: Ninety male C57BL/6 mice, 6 to 8 weeks old, were randomly divided into 3 groups according to the table of random numbers: a control group, a model group and a treatment group(n = 30 each). Bleomycin was injected to the mice in the latter 2 groups by single intratracheal injection to duplicate the pulmonary fibrosis model, while the control group was injected with saline. From the next day, the mice in the treatment group received 1, 25 (OH) 2D3 (0.5 µg·kg(-1)·d(-1)) diluted in olive oil by gavage daily, while the other groups were treated with equivalent olive oil. Ten mice in each group were killed randomly on day 14, 21 and 28 after surgery respectively. Pulmonary alveolitis and fibrosis were evaluated by using hematoxylin-eosin and Masson stain method. The content of hydroxyproline was measured by acid hydrolysis method. The mRNA levels of collagen1α1, α-SMA, Wnt3a, Wnt4, and Wnt7a in the lung tissues were measured by real-time RT-PCR, while the protein expression of α-SMA and ß-catenin were assessed by immunohistochemistry. RESULTS: Pulmonary alveolitis at day 14, 21 and fibrosis at day14, 21, 28 in the treatment group were remarkably reduced compared to the model group (all P < 0.05). Compared with the model group, the treatment group showed decreased content of hydroxyproline, decreased mRNA levels of collagen1α1, α-SMA, Wnt3a, Wnt4 and decreased protein expression of α-SMA and ß-catenin at the 3 time points (all P < 0.05). The content of hydroxyproline and the mRNA levels of collagen1α1, α-SMA, Wnt3a, Wnt4, Wnt7a in the treatment group at 28 d were 0.67 ± 0.14, 1.66 ± 0.34, 1.37 ± 0.41, 1.43 ± 0.27, 1.29 ± 0.19, 1.18 ± 0.20, respectively, all of which were significantly lower than those in the model group (1.10 ± 0.16, 3.50 ± 0.74, 2.68 ± 0.61, 2.60 ± 0.58, 2.23 ± 0.45, 1.93 ± 0.36, respectively). Protein expression of α-SMA and ß-catenin in the treatment group were 0.44 ± 0.13 and 0.25 ± 0.05, respectively, which were also significantly lower than those of the model group(0.98 ± 0.20, 0.58 ± 0.06, respectively). CONCLUSION: 1, 25 (OH) 2D3 was shown to reduce pulmonary fibrosis induced by bleomycin in mice, and its mechanisms might be associated with Wnt signaling suppression.

[Genotoxicity of drinking water during chlorine and chloramine disinfection and the influence of disinfection conditions using the umu-test].

In this study, the effects of disinfectant dosage, reaction time and the ratio of Cl2 to N of disinfectant on genotoxicity of effluent of ozone-biological activated carbon (O3-BAC) during chlorine or chloramine disinfection were investigated using umu-test. It was found that, the genotoxicity of effluent of O3-BAC before disinfection ranged from 20-70 ng/L, and it increased after disinfection by chlorine or chloramines. With the same reaction time(24 h), genotoxicity after chlorination (40-95 ng/L) was higher than that after chloramination (20-40 ng/L) under same initial dosage. For chlorination, with initial dosage increasing from 0 mg/L to 10 mg/L, genotoxicity increased firstly, and got the maximum value at about 0.5-1 mg/L dosage, then decreased and got the minimum value at about 3-5 mg/L dosage, and finally increased again. For chloramination, genotoxicity didn't change that much. With the dosage of 3 mg/L and reaction time increasing from 0 h to 72 h, no matter for chlorine or chloramines disinfection, genotoxicity of effluent of O3-BAC both increased firstly, and got the maximum value at about 2 h, then decreased and got the minimum value at about 18 h, and finally increased again, and genotoxicity after chlorine disinfection (83-120 ng/L) was higher than that after chloramines disinfection (20-62 ng/L) under same reaction time. Further more, effects of the different ratios of Cl2 to N of disinfectant on genotoxicity of effluent of O3-BAC were also studied. Results of this study demonstrate that under test conditions, chloramine disinfection is safer than chlorine disinfection in the aspect of genotoxicity for drinking water, and the changes of genotoxicity are different from those of total HAAs.

[Impacts of the hydraulic characteristics of pilot clearwell on chlorine disinfection efficiency].

A pilot clearwell was used to simulate the chlorine disinfection process with the Bacillus subtilis spores as the target microbe. The effluent of the activated carbon filter tank was radiated by low pressure UV lamp and then used as the influent the pilot clearwell. The impacts of hydraulic characteristics of pilot clearwell on disinfection efficiency of Bacillus subtilis spores was studied under different hydraulic characteristics which was changed by the number of the baffles. Under the conditions of this experiment, the inactivation coefficients of Bacillus subtilis spores with NaC10 as disinfectant which were calculated by Ct10 value were almost same under different hydraulic characteristics, but the inactivation coefficients which were calculated by CT value were very different under different hydraulic characteristics. This verified that it was more reasonable to evaluate the disinfection efficiency by Ct10 value than CT value. When Ct10 value was in the range of 100 - 300 mg x min/L, the inactivation coefficient of Bacillus subtilis spores with NaClO as disinfectant was 0.001 6 L(mg x min), which highly coincided with others' results. When CT value was in the range of 100 - 700 mg x min/L, under the same CT value, the disinfection efficiency of target microbe would be notably enhanced by increasing the number of baffles which would improve the hydraulic characteristics. So the results verified that the disinfection efficiency could be enhanced by improving the hydraulic characteristics of the clearwell.

[Case study of red water phenomenon in drinking water distribution systems caused by water source switch].

Red water phenomenon occurred in some communities of a city in China after water source switch in recent days. The origin of this red water problem and mechanism of iron release were investigated in the study. Water quality of local and new water sources was tested and tap water quality in suffered area had been monitored for 3 months since red water occurred. Interior corrosion scales on the pipe which was obtained from the suffered area were analyzed by XRD, SEM, and EDS. Corrosion rates of cast iron under the conditions of two source water were obtained by Annular Reactor. The influence of different source water on iron release was studied by pipe section reactor to simulate the distribution systems. The results indicated that large increase of sulfate concentration by water source shift was regarded as the cause of red water problem. The Larson ratio increased from about 0.4 to 1.7-1.9 and the red water problem happened in the taps of some urban communities just several days after the new water source was applied. The mechanism of iron release was concluded that the stable shell of scales in the pipes had been corrupted by this kind of high-sulfate-concentration source water and it was hard to recover soon spontaneously. The effect of sulfate on iron release of the old cast iron was more significant than its effect on enhancing iron corrosion. The rate of iron release increased with increasing Larson ratio, and the correlation of them was nonlinear on the old cast-iron. The problem remained quite a long time even if the water source re-shifted into the blended one with only small ratio of the new source and the Larson ratio reduced to about 0.6.

[Development of a fluorescence polarization immunoassay for sulfamerazine].

A fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody for the determination of sulfamera (SMR) was developed. The fluorescein-labeled SMR and sulfamethazine (SMZ) were synthesized and purified by thin layer chromatography (TLC). The optimized SMR FPIA had a dynamic range from 5.4 to 218.8 ng x mL(-1) with IC50 value of 23.4 ng x mL(-1) and a detection limit of 2.3 ng x mL(-1). The specificity of the FPIA for SMR was investigated using other 16 sulfonamides and the cross-reactivity for SMR, SMZ and sulfadiazine (SDZ) was 100%, 25% and 8.6%, respectively.

[Development of fluorescence polarization immunoassay for determination of pesticides and veterinary drugs].

Fluorescence polarization immunoassay (FPIA) is a fast screening technique based on immune competition and fluorescence polarization principle and is most used in the determination of small molecular substance (antigen). FPIA is based on the increase in polarization of the fluorescence of small fluorescent-labeled antigen when bound by specific antibody. FPIA is a homogeneous technique and not affected by solution color and the sensitivity of instrument. No separation step is required for FPIA. Simplifying the assay and minimizing the analysis time are the most notable advantages of FPIA over other immunoassays and FPIA is suitable to screening a large number of samples. The technique has been applied to the determination of pesticides and veterinary drugs in environment and food samples, while no studies have been reported in the correlative field in China. The present paper presents the principle and history of FPIA and its application in the screening determination of pesticides and veterinary drugs.