[Antimicrobial susceptibility and drug-resistance genes of Yersinia spp. of retailed poultry in 4 provinces of China].

Objective: To monitor the antimicrobial resistance and drug-resistance genes of Yersinia enterocolitis, Y. intermedia and Y. frederiksenii recovered from retailed fresh poultry of 4 provinces of China. Methods: The susceptibility of 25 isolated Yersinia spp. to 14 classes and 25 kinds of antibiotics was determined by broth microdilution method according to CLSI (Clinical and Laboratory Standards Institute). The antibiotic resistance genes were predicted with antibiotic resistance genes database (ARDB) using whole genome sequences of Yersinia spp. Results: In all 22 Y. enterocolitis tested, 63.7% (14 isolates), 22.8% (5 isolates), 4.6% and 4.6% of 1 isolates exhibited the resistance to cefoxitin, ampicillin-sulbactam, nitrofurantoin and trimethoprim-sulfamethoxazole, respectively. All the 25 isolates were multi-drug resistant to more than 3 antibiotics, while 64.0% of isolates were resistant to more than 4 antibiotics. A few Y. enterocolitis isolates of this study were intermediate to ceftriaxone and ciprofloxacin. Most Yersinia spp. isolates contained antibiotic resistance genes mdtG, ksgA, bacA, blaA, rosAB and acrB, and 5 isolates recovered from fresh chicken also contained dfrA1, catB2 and ant3ia. Conclusion: The multi-drug resistant Yersinia spp. isolated from retailed fresh poultry is very serious in the 4 provinces of China, and their contained many kinds of drug-resistance genes.

[Sleep problems and the association with the levels of 6-sulfatoxymelatonin in children with autism spectrum disorder].

Objective: To identify the prevalence of sleep problems in children with autism spectrum disorder (ASD) and to explore the association with the main melatonin metabolite, 6-sulfatoxymelatonin (6-SM). Method: This was a prospective case-control study. Children with ASD were recruited from Child Development and Behavioral Research Center (CDBRC) of the Harbin Medical University and Harbin Special Education School from October 2015 to April 2017 (ASD group) . Healthy controls were selected from five kindergartens and one primary school in Harbin by the stratified cluster random sampling (control group) . The Children's Sleep Habits Questionnaire (CSHQ) was used to investigate the sleep problems of the two groups. The patients were matched in a 1∶1 ratio for the age and sex, and the urine samples of case-control pairs were collected in the morning. The level of 6-SM was measured by the enzyme linked immunosorbent assay (ELISA). The student's t test was used for comparison between the ASD group and control group, and the Pearson correlation analysis was used to determine the correlation difference. Result: A total of 212 ASD children (mean (±SD) age was (6.0±2.7) years, and 181 patients (85.4%) were male), and a total of 334 healthy children(mean (±SD) age was (5.9±2.6) years, and 272 patients (81.4%) were male) were recruited. Among them, 101 matched case-control pairs completed the collection of urine samples. According to the statistical analysis, the scores of total CSHQ, bedtime resistance, sleep onset delay, sleep duration, night waking, parasomnia, sleep disordered breathing and daytime sleepiness in children with ASD were significantly higher than those in the control group (48.2±6.2 vs. 46.6±5.4, 11.4±2.5 vs. 10.7±2.8, 1.7±0.8 vs. 1.5±0.7, 4.1±1.4 vs. 3.7±1.1, 4.2±1.5 vs. 3.8±1.1, 8.5±1.5 vs. 8.3±1.4, 3.7±1.0 vs. 3.4±0.8, 11.7±2.5 vs. 12.4±2.7, t=3.16, 3.00, 3.23, 2.76, 3.19, 1.99, 3.45,-2.72, P=0.002, 0.003, 0.001, 0.006, 0.002, 0.048, 0.001, 0.007), the level of 6-SM was significantly lower in children with ASD than that of healthy controls ((1.24±0.50) vs. (1.68±0.63)µg/h, t=-5.50, P<0.01), and the total CSHQ score was negatively correlated with the level of 6-SM (r=-0.50, P<0.01). Conclusion: The children with ASD were at high risk for sleep problems, and the melatonin metabolite of ASD group was abnormal compared with that of the control group. Moreover, there was a negative correlation between the severity of sleep problems and the level of 6-SM in ASD children. The results of our study indicate that the abnormal melatonin metabolism may be one of the causes of sleep problems in children with ASD.

Spatiotemporal tuning in mouse primary visual cortex.

The neural correlates of visual motion perception have historically been studied in non-human primates. However, the mouse has recently gained popularity as a model for studying vision primarily driven by the hope that the genetic tools available in this species may contribute to our understanding of visual processing in the cortex. A recent calcium-imaging study on the spatiotemporal tuning of mouse striate and extrastriate cortex revealed that neurons in the primary visual cortex (V1) were almost never speed tuned, whereas previous electrophysiological studies in macaques noted around one quarter of V1 neurons appeared to be selective for a particular stimulus speed. We were interested in whether this discrepancy was due to methodological or species differences, so we measured the spatiotemporal tuning of mouse V1 neurons using standard electrophysiological techniques. Using comparable analyses to previous studies of speed tuning, our data showed that speed tuning is rare in mouse V1, which corroborates earlier studies in mouse and points to a species difference in motion processing in early cortex between macaques and other mammals.

Methods for reconstruction of 2-D sequences from Fourier transform magnitude.

The Gerchberg-Saxton (GS) algorithm and its generalizations have been the main tools for phase retrieval. Unfortunately, it has been observed that the reconstruction using these algorithms does not always converge to the correct result even if the desired solution satisfies the uniqueness condition. In this paper, we propose a new deautocorrelation algorithm and a few auxiliary techniques. We recommend that a combination of the iterative Fourier transform (IFT) algorithm with our new algorithm and techniques can improve the probability of success of phase retrieval. A pragmatic procedure is illustrated. Different reconstruction examples that are difficult to reconstructed using the single IFT algorithm are used to show the robustness and effectiveness of the new combination of algorithms. If the given Fourier modulus data contain no noise, it is sometimes possible to get a perfect reconstruction. Even when the signal-to-noise ratio (SNR) of the Fourier modulus data is only 10 dB, a meaningful result remains reachable for our examples. A concept concerning the intrinsic ambiguity of phase retrieval is suggested. We emphasize the necessity of verification of the solution, since the available phase retrieval algorithms are incompetent for distinguishing between an intrinsically ambiguous solution and the true solution.

On the computational model of a kind of deconvolution problem.

It is known that discretization of a continuous deconvolution problem can alleviate the ill-posedness of the problem. The currently used circulant matrix model, however, does not play such a role. Moreover, the approximation of deconvolution problems by circulant matrix model is rational only if the size of the kernel function is very small. We propose an aperiodic model of deconvolution. For discrete and finite deconvolution problems the new model is an exact one. In the general case, the new model can lead to a nonsingular system of equations that has a lower condition number than the circulant one, and the related computations in the deconvolution can be done efficiently by means of the DFT technique, as in the ease for circulant matrices. The rationality of the new model holds without regard to the size of the kernel and the image. The use of the aperiodic model is illustrated by gradient-based algorithms.