In this study ,a wild type Salmonella typhimurium (S .typhimurium) strain was isolated and identified in Hong Kong (S129) ,then the asdA gene was knocked out and replaced with kanamycin resistant gene in a Salmonella typhi-murium strain S129 using the λ RED-mediated recombination method .The constructed mutant asdAΔS129 was validated by culturing in the presence or absence of 2 ,6-diaminopimelic acid (DAP) growth in vitro and evaluating its virulence in BALB/c mice challenge assay .Therefore ,this study has demonstrated that an asdA mutant Salmonella typhimurium has been success-fully constructed .

Objective To explore the correlations of diffusion-weighted imaging (DWI) types and the degree of neurologic impairment in acute ischemic stroke patients with atrial fibrillation.Methods DWI images and National Institutes of Health Stroke Scale(NIHSS) of 186 patients with acute ischemic stroke patients with atrial fibrillation were collected retrospectively.The correlation of DWI features and NIHSS was analyzed.Results On DWI,all acute ischemic stroke patients with atrial fibrillation presented high signal intensity.Single cortex-subcortical infarction mostly appeared in the anterior circulation(94,50.5%);Multi-infarction commonly occurred in the posterior circulation(18,13.0%);The neurological deficit scores of subcortical-cortex infarction in the left anterior circulation(16.75±7.10) were higher than that in the right side(13.50±5.70)(P<0.05).The neurological deficit scores of cortex-subcortical infarction in the posterior circulation (6.38±2.03) were significantly lower than that in the multi-infarction (16.77±8.90) (P<0.05).Conclusion DWI types are valuable for etiological diagnosis in ischemic stroke.Combination with NIHSS score could provide a basis for clinical individual treatment programs selection and prognostic evaluation.

Objective To investigate the changes of the gray matter in patients with rheumatoid arthritis (RA) based on the voxel based morphometry (VBM).Methods 35 patients with RA and 30 healthy volunteers with age,sex and education level matched performed a high-resolution 3D-T1-weighted whole brain structural scan by GE Signa HDxt 1.5T MRI scanner.The high resolution T1WI images were preprocessed by the VBM 12 implemented in the SPM 12 software to display the gray matter structures of the RA patients and the healthy volunteers.T test was used to compare the morphological changes of gray matter between the RA patients and the volunteers.Results The gray matter volume gray matter volume in the right lentiform nucleus,left frontal lobe and left cerebellum posterior lobe significantly decreased in RA patients,and their gray matter volume had no correlation with the clinical indications.The increase of gray matter volume was not found in the RA patients.Conclusion RA patients show decreased gray matter volume in several cerebral regions,which suggests that RA can lead to the brain structural abnormalities.VBM can provide an objective imaging evidence to evaluate the cerebral morphological abnormalities of RA.