Ubiquitination and regulation of Smad7 in the TGF-ß1/Smad signaling of aristolochic acid nephropathy.

Aristolochic acid I (AAI) affects TGF-ß1/Smad signaling, which causes AA nephropathy (AAN), but the mechanisms are not fully understood. We aimed to clarify whether Arkadia and UCH37 participate in TGF-ß1/Smad signaling via Smad7, and the regulatory mechanisms of Smad7. One side, mice and cultured mouse renal tubular epithelial cells (RTECs) were treated with various AAI doses and concentrations, respectively; on the other side, RTECs were transfected with small interfering RNA (siRNA) expression vectors against Arkadia and UCH37 and then treated with 10 µg/ml AAI. And then detect the mRNA and protein levels of Smad7, UCH37, Arkadia and any other relative factors by RT-PCR and Western blotting. In kidney tissues and RTECs, the mRNA and protein levels of Smad7 decreased with increasing AAI doses concentrations by real-time PCR and Western blotting, whereas those of Arkadia, UCH37, Smad2, Smad3 and TßRI increased. Cells transfected with the Arkadia siRNA expression vector showed reduced mRNA and protein levels of vimentin, α-SMA, Smad2, Smad3 and TßRI after AAI treatment, while those of CK18 and Smad7 increased compared with those of untransfected RTECs. Conversely, cells transfected with the UCH37 siRNA expression vector showed the opposite effect on analyzed signaling molecules after AAI treatment. Arkadia and UCH37 participate in TGF-ß1/Smad signaling-mediated renal fibrosis, and Smad7 blocks TGF-ß1 signaling by inhibiting Smad2/Smad3 phosphorylation and enhancing the degradation of TßRI.

Expression of histone deacetylase-1 and p300 in aristolochic acid nephropathy models.

Aristolochic acid nephropathy (AAN) is mainly caused by aristolochic acid I (AAI), but the actual mechanism is still uncertain. The current study explored the correlation among the expression of Smad7, p300, histone deacetylase-1 (HDAC1) and the development of AAN using transmission electron microscopy (TEM), RT-PCR, and western blotting in the AAN mouse model and in the AAN cell model. TEM revealed that the renal tubular epithelial cells from the AAI-treated mice presented organelle damages and nuclear deformation. We found that a certain dose of AAI caused renal fibrosis and induced renal tubular epithelial cells to differentiate into myofibroblasts. There was a gradual increase in the expression of HDAC1 mRNA and protein observed using RT-PCR and western blotting in the AAN cell model compared with the control group. Gradual decrease in the expression of Smad7 and p300 mRNA and protein was revealed in the AAN mouse and cell models compared with the control group. These results suggest that AAI dose dependently contributed to the development of AAN, and HDAC1 and p300 participate in the modulation of TGF-ß/Smad pathway-mediated renal interstitial fibrosis.

Characterization of multidrug-resistant Salmonella enterica serovars Indiana and Enteritidis from chickens in Eastern China.

A total of 310 Salmonella isolates were isolated from 6 broiler farms in Eastern China, serotyped according to the Kauffmann-White classification. All isolates were examined for susceptibility to 17 commonly used antimicrobial agents, representative isolates were examined for resistance genes and class I integrons using PCR technology. Clonality was determined by pulsed-field gel electrophoresis (PFGE). There were two serotypes detected in the 310 Salmonella strains, which included 133 Salmonella enterica serovar Indiana isolates and 177 Salmonella enterica serovar Enteritidis isolates. Antimicrobial sensitivity results showed that the isolates were generally resistant to sulfamethoxazole, ampicillin, tetracycline, doxycycline and trimethoprim, and 95% of the isolates sensitive to amikacin and polymyxin. Among all Salmonella enterica serovar Indiana isolates, 108 (81.2%) possessed the blaTEM, floR, tetA, strA and aac (6')-Ib-cr resistance genes. The detected carriage rate of class 1 integrons was 66.5% (206/310), with 6 strains carrying gene integron cassette dfr17-aadA5. The increasing frequency of multidrug resistance rate in Salmonella was associated with increasing prevalence of int1 genes (rs = 0.938, P = 0.00039). The int1, blaTEM, floR, tetA, strA and aac (6')-Ib-cr positive Salmonella enterica serovar Indiana isolates showed five major patterns as determined by PFGE. Most isolates exhibited the common PFGE patterns found from the chicken farms, suggesting that many multidrug-resistant isolates of Salmonella enterica serovar Indiana prevailed in these sources. Some isolates with similar antimicrobial resistance patterns represented a variety of Salmonella enterica serovar Indiana genotypes, and were derived from a different clone.

Simultaneous determination of cyromazine and dicyclanil in animal edible tissues using UPLC-MS/MS.

Cyromazine and dicyclanil are both used as insect growth regulators. This paper describes an easy and innovative simultaneous extraction method for residues of cyromazine and dicyclanil in food of animal origin, and a confirmation procedure using UHPLC-MS/MS. The sample was extracted, deproteinised by 1% trichloracetic acid in water-acetonitrile, followed by selective defatting using hexane based on the degree of matrix complexity; cleaned-up on an mixed-mode cation exchange (MCX) cartridge; and quantified by using matrix-matched calibration. The mean recoveries were all between 62.0% and 99.2%, and the RSDs were all below 9.94%. The present method was rapid, sensitive and reliable, which was applied to the quantitative analysis of these residues in animal tissues.

Prevalence of antimicrobial resistance among Salmonella isolates from chicken in China.

We evaluated the antimicrobial resistance of Salmonella isolated in 2008 from a chicken hatchery, chicken farms, and chicken slaughterhouses in China. A total of 311 Salmonella isolates were collected from the three sources, and two serogroups of Salmonella were detected, of which 133 (42.8%) consisted of Salmonella indiana and 178 (57.2%) of Salmonella enteritidis. The lowest percentage of S. indiana isolates was found in the chicken hatchery (4.2%), followed by the chicken farms (54.9%) and the slaughterhouses (71.4%). More than 80% of the S. indiana isolates were highly resistant to ampicillin (97.7%), amoxicillin/clavulanic acid (87.9%), cephalothin (87.9%), ceftiofur (85.7%), chloramphenicol (84.9%), florfenicol (90.9%), tetracycline (97.7%), doxycycline (98.5%), kanamycin (90.2%), and gentamicin (92.5%). About 60% of the S. indiana isolates were resistant to enrofloxacin (65.4%), norfloxacin (78.9%), and ciprofloxacin (59.4%). Of the S. indiana isolates, 4.5% were susceptible to amikacin and 5.3% to colistin. Of the S. enteritidis isolates, 73% were resistant to ampicillin, 33.1% to amoxicillin/clavulanic acid, 66.3% to tetracycline, and 65.3% to doxycycline, whereas all of these isolates were susceptible to the other drugs used in the study. The S. indiana isolates showed resistance to 16 antimicrobial agents. Strains of Salmonella (n = 108) carrying the resistance genes floR, aac(6')-Ib-cr, and bla(TEM) were most prevalent among the 133 isolates of S. indiana, at a frequency of 81.2%. The use of pulsed-field gel electrophoresis to analyze the S. indiana isolates that showed similar antimicrobial resistance patterns and carried resistance genes revealed six genotypes of these organisms. Most of these isolates had the common pulsed-field gel electrophoresis patterns found in the chicken hatchery, chicken farms, and slaughterhouses, suggesting that many multidrug-resistant isolates of S. indiana prevailed in the three sources. Some of these isolates were not derived from a specific clone, but represented a variety of genotypes of S. indiana.

Forsythoside a inhibits the avian infectious bronchitis virus in cell culture.

Forsythoside A is a polyphenolic constituent of the fruits of Forsythia suspensa Vahl. which is widely used as an antiinflammatory agent in traditional Chinese medicine. In the present study, the effects of forsythoside A on cell infection by avian infectious bronchitis virus were assessed. A real-time fluorescence quantitative PCR assay was used to determine mRNA content of IBV N gene. The pretreatment of cells with forsythoside A, adding forsythoside A post infection of cells, and treatment of virus with forsythoside A were analysed. The inhibitory effect of forsythoside A was confirmed by infecting primary chicken embryo kidney cells. Infected cells were inhibited by forsythoside A treatment. The data indicated that forsythoside A has the potential to prevent IBV infection in vitro. Copyright © 2010 John Wiley & Sons, Ltd.

Determination of para red, Sudan dyes, canthaxanthin, and astaxanthin in animal feeds using UPLC.

A simple high-performance liquid chromatography method was developed for quantitative determination of para red, Sudan I, Sudan II, Sudan III, Sudan IV, canthaxanthin, and astaxanthin in feedstuff. The sample was extracted using acetonitrile and cleaned up on a C(18) SPE column. The residues were analyzed using ultra-performance liquid chromatography coupled to a diode array detector at 500 nm. The mobile phase was acetonitrile-formic acid-water with a gradient elution condition. The external standard curves were calibrated. The mean recoveries of the seven colorants were 62.7-91.0% with relative standard deviation 2.6-10.4% (intra-day) and 4.0-13.2% (inter-day). The detection limits were in the range of 0.006-0.02 mg/kg.

TGF-beta 1/Smads signaling stimulates renal interstitial fibrosis in experimental AAN.

Aristolochic acid nephropathy (AAN) is regarded as a kind of rapidly progressive renal fibrosis caused by the ingestion of herbal remedies containing aristolochic acids (AA). A mouse model of AAN was used to assess the patterns of renal injury and TGF-beta1/Smads signaling pathway during the evolution of tubulointerstitial damage and to relate them to the development of fibrosis. A total of 28 mice were randomly assigned to four groups. Three groups were given aristolochic acid I (AAI) at different doses consecutively by gavage for 30 days, while the control group received only phosphate-buffered saline (PBS). Immunohistochemistry and semi-quantitative reverse transcriptase (RT-PCR) detection of the increased expression of fibroblast marker vimentin and de novo expression of alpha-smooth muscle actin (alpha-SMA) with the loss of epithelial maker cytokeratin 18 (CK18) can be utilized to assess AAI-induced tubular necrosis and extensive cortical interstitial fibrosis in a dose-dependent manner. Transforming growth factor-beta1 (TGF-beta1) has been widely recognized as a key fibrogenic cytokine. In our study, TGF-beta1 in the group at dose of 12 mg/kg/ day AAI increased 109.9% compared to control. Smad2 mRNA level in the group at dose of 4.2 mg/kg/day AAI increased 106.4%, and declined 12% in the group at dose of 12 mg/kg/day AAI; Smad4 expression was down-regulated in experimental groups, which declined 13% in the group at dose of 4.2 mg/kg/day AAI. Smad7 mRNA level was down-regulated by AAI in dose-dependence. Collectively, the involvement in interstitial fibrosis progression of active TGF-beta is highly suggested, via the Smads intracellular signaling pathway. These results may be attributed to the dosage of drug and the treatment of renal interstitial fibrosis.

TGF-beta1/Smad7 signaling stimulates renal tubulointerstitial fibrosis induced by AAI.

A progressive tubulointerstitial nephropathy is mainly induced by aristolochic acid I (AAI), but a comprehensive understanding of this process is still missing. By using mouse primary renal tubular epithelial cells (RTECs) cultured in vitro and combining with two AAI treatment types (dose-response studies and time-response studies), we sought to investigate the nephrotoxicity of AAI further. Following our molecular and pharmacological studies, we found that high doses of AAI could lead to the death of RTECs within a short time, but low doses in a long duration only induce the epithelial cells to transform into myofibroblasts (MFs). This was also immediately identified by the increased expression of vimentin and de novo expression of alpha-smooth muscle actin (alpha-SMA) with the loss of cytokeratin 18 (CK18) by semiquantitative reverse transcriptase-PCR (RT-PCR) and immunofluorescence staining. The transcriptional level of transforming growth factor-beta1 (TGF-beta1) in the group treated with AAI significantly increased twice as much as the control. Smad2 mRNA level in the group with 50 ng/mL AAI declined by 23.4% at 24 hr, then increased by 180.0% at 36 hr; it was also evidently increased (217.4%) after being treated with 30 ng/mL AAI for 24 hr. Meanwhile, Smad7 mRNA level was down-regulated by AAI in dose- and time-dependence. Furthermore, by cotransfecting in mouse primary RTECs, the transcriptional level of Smad7 promoter-luciferase reporter gene was significantly down-regulated by AAI (300 ng/mL), and the expression of myofibroblast-specific markers induced by AAI was also suppressed by the specific antagonist of TGF-beta1 receptors (SB-431542). Collectively, the present results suggest that AAI may induce cytotoxicity through its conductive epithelial to mesenchymal transition, and TGF-beta1/Smad7 signaling can stimulate renal tubulointerstitial fibrosis induced by AAI.