Fluorescence immunosensor based on a specific monoclonal antibody for highly sensitive and rapid detection of gizzerosine in feed.

Gizzerosine is a biogenic amine produced in fish meal drying process and posted higher mortality due to gizzard erosion in poultry than histamine. However, it is difficult to obtain gizzerosine and achieve sensitive practical detection due to its simple structure. Herein, a monoclonal antibody (mAb) specific to gizzerosine was generated based on the new structural design and a fluorescence immunosensor for sensitive and on-site detection of gizzerosine in feed was first established. Molecular modeling of the three-dimensional (3D) structure and surface electrostatic potential of gizzerosine indicated that the carbonyl group of gizzerosine hapten might affect the important sites of antigen-antibody interactions. The proposed structure was used to obtain the sensitive and specific mAb with IC50 of 3.88 ng/mL in indirect competitive ELISA which was approximately 100-fold lower than that of direct competitive ELISA. Considering the practical application scenarios, a fluorescence immunosensor based on microporous dry method integrated with independent quality control line was established to improve detection stability. Under the optimum conditions, the proposed immunosensor showed a good linear relationship from 1.10 to 19.78 ng/mL and provided a low detection limit of 50 ng/g which was approximately 80-fold lower than the maximum recommended amount (0.4 mg/kg) of gizzerosine in feed. The recoveries of 6 kinds of feed ranged from 83.1 % to 114.3 %, which was in good consistence with that of UHPLC-MS/MS. Overall, this work provides a fast, cost-effective and reliable on-site tool for rapid screening of gizzerosine residues in feed samples.

[Relationship between viral burden in urine and hearing loss in neonates with cytomegalovirus infection].

OBJECTIVE: To determine the relationship between viral burden in urine and hearing loss in neonates with cytomegalovirus (CMV) infection. METHODS: Twenty-two neonates with CMV infection between April 2006 and January 2010 were enrolled. Their viral burden in urine and hearing loss information were studied. The receiver operating characteristic curve (ROC) was constructed and the cutoff was determined based on their medical information. The hearing levels were evaluated by brain stem auditory evoked potential (BAEP) during the age of 3 to 6 months in 20 patients. RESULTS: The viral burden in urine in neonates with abnormal BAEP was higher than that in neonates with normal BAEP (5.06 ± 1.50 vs 3.73 ± 0.86, P<0.05). Hearing loss was predicted with a sensitivity of 0.545 and a specificity of 1.0 by using ROC at the cutoff point of 5.1 which were defined after logarithmic conversion at 1.27×10(5) copies/mL of CMV burden in urine. The incidence of hearing loss during the age of 3 to 6 months was strikingly higher in high viral burden group than that in low viral load group (P<0.05). CONCLUSIONS: The viral burden in urine can predict the possibility of hearing loss in neonates with CMV infection. Hearing loss is likely to be developed when viral burden in urine ≥1.27×10(5) copies/mL in neonates with CMV infection.

[Retinoic acid protects neonatal rats from hyperoxia-induced lung injury through down-regulating connective tissue growth factor].

OBJECTIVE: To explore the mechanism of retinoic acid (RA)　protection　against hyperoxia-induced lung injury. METHODS: Ninety Sprague-Dawley rats were randomly assigned into three groups (n=30 each): air control group (exposed to air) and hyperoxia groups (exposed to 85% oxygen) with and without RA treatment. The RA-treated hyperoxia group received an intraperitoneal injection of RA (500 µg/kg) daily. Lungs were removed by tnoracotomy 4, 7 and 14 days after exposure. Radical alveolar counts (RAC) were observed by hematoxylin and eosin staining under a light microscope. The mRNA level of CTGF in lungs was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of CTGF protein in lungs was detected by immunohistochemistry. RESULTS: With the prolonged hyperoxia exposure, the lungs developed inflammatory cell infiltration, alveolar structure disorders, a decrease in the number of alveoli, and alveolar interstitial thickening in the hyperoxia groups with and without RA treatment. Pathological changes in the RA-treated hyperoxia group were less severe than the untreated hyperoxia group. The CTGF mRNA and protein expression were up-regulated in the hyperoxia groups with and without RA treatment 7 and 14 days after exposure compared with the air control group. Significantly decreased CTGF mRNA and protein expression were noted in the RA-treated hyperoxia group compared with the untreated hyperoxia group 14 days after exposure. CONCLUSIONS: The expression of CTGF mRNA and protein increases in neonatal rats with hyperoxia-induced lung injury. RA may provide protections against the lung injury possibly through down-regulating CTGF expression.