Nisin is a cationic antimicrobial peptide produced by some lactic acid bacteria. However, expression of nisin resistance protein (NSR) could confer nisin resistance on some non-nisin-producing Lactococcus lactis. To deeply elucidate molecular mechanism underlying NSR-mediated nisin resistance, an NSR mutant with N-terminal 38 amino acid residues deleted (NSR?38) was overexpressed in Escherichia coli by fusion with GST. Purified NSR?38 was obtained through glutathione (GSH) affinity chromatography followed by cleavage of GST tag. Putative proteolytic activity of NSR?38 was determined in vitro against nisin. Antimicrobial activity analysis revealed that nisin lost its bactericidal activity after incubation with NSR?38. Further reversed-phase high performance liquid chromatography (RP-HPLC) analysis indicated that NSR?38 displayed proteolytic activity against nisin, thus inactivating the antimicrobial peptide. The current study paves the way for in-depth functional studies on NSR.

Objective To evaluate the growth inhibition and apoptosis of human monocytic leukemia THP-1 cell line by using 5,8-dimethyl-2-β-hydroxyisovalerylshikonin (SK36) and explore its preliminary mechanism. Methods CCK colorimetric assay and cell counting was used to examine the growth inhibition of shikonin on THP-1 cells. The apoptosis of THP-1 cells was detected by Annexin V/PI double labeling. The activation of Caspase-3 apoptosis pathway was determined by FCM. The apoptosis and the necrosis of THP-1 cells were detected by the laser scanning confocal microscopy. Results When the THP-1 cells were treated with SK36 at 1.02 μg/ml for 24 h and 48 h, the growth inhibition was dose-dependent. The cell apoptotic rate of THP-1 cells treated with 1.02 μg/ml evaluated by FCM with Annexin V/PI double labeling staining were (40.61 ±2.13) % and (67.40±9.15) % at 24 h and 48 h after treatment, respectively, which were significantly higher than that of the control group [(16.97±0.61) %] ([ = 18.444, t = 9.528, P <0.01). SK36 could induce THP-1 cells apoptosis involving the activation of Caspase-3 (F= 323.61, P<0.01). Conclusion SK36 can induce human THP-1 cells to undergo apoptosis, and its primary mechanism was to activate the Caspase-3.

Objective To study the molecular biology of rifampin-depending M. Tuberculosis. Methods The seguence (a 319-bp DNA fragment) of rpoB gene were analyzed by automated DNA sequencing machine. (2) The fingerprints of genomic DNA were obtained by random amplified polymorphic DNA (RAPD) fingerprinting. (3)The protein electrophoresis of bacterium by SDS-polyacrylamide gel (SDS-PAG).(4) The cases of pulmonary tuberculosis by rifampin-depending strains were retrospectively analyzed. Results (1) rpoB gene sequenced: The point mutationrate of rifampin-depending strainswas 96.7%(29/30) and that of rifampin-residtant strains 81.1%(30/37), P

Objective To analyze the level of cardiac troponin I (cTnI) in children with left-to-right shunt congenital heart disease (CHD). Methods In this study, 146 children with secundum atrial septal (ASD) defect, 132 children with ventricular septal defect (VSD) and 300 healthy children were recruited. The levels of cTnI and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured and their correlation with clinical data was analyzed. Results The serum cTnI and NT-proBNP levels in both ASD and VSD patients were signiifcantly higher than those in normal children (H=3.89 and 5.27, P<0.01). The serum cTnI and NT-proBNP levels in VSD patients were signiifcantly higher than those in ASD patients (P<0.05). The ratio of pulmonary to systemic arterial pressure (Pp/Ps), pulmonary vascular resistance index (PVRI) and standardized left ventricular end diastolic volume in VSD patients were signiifcantly higher than those in ASD patients (P<0.05). Multiple regression analysis showed that Pp/Ps was signiifcantly correlated with cTnI in VSD patients. (β=0.81, SE=0.03, P=0.000). Conclusions Signiifcant volume and pressure overload due to a left-to-right shunt induce myocardial injury and could lead to irreversible myocardial remodeling in children with CHD. The serum cTnI level is a sensitive biomarker for myocardial damage in VSD patients.

Objective To investigate the efficacy and clinical value of balloon-assisted clipping for the treatment of giant unruptured intracranial aneurysms of internal carotid artery. Methods Patients with giant unruptured intracranial aneurysm of intracranial segment of internal carotid artery treated with balloon-assisted clipping in the Department of Neurosurgery, Xiangya Hospital, Central South University from September 2017 to May 2018 were enrolled retrospectively. The proximal internal carotid artery or the aneurysm neck were temporarily blocked by balloon, and then the aneurysm was clipped in the hybrid operating room. Demographic data, preoperative symptoms, aneurysm characteristics, position of balloon placement, intraoperative angiography, complications, and follow-up results were collected. Results A total of 12 patients with giant (diameter >2 cm) unruptured intracranial aneurysm of intracranial segment of internal carotid artery were enrolled. They were all successfully clipped using balloon-assisted clipping in the hybrid operating room. Among them, 1 was located in the ophthalmic segment, 3 in the supraclinoid segment, 4 in the posterior communicating segment, 2 in the anterior choroidal artery segment, and 2 in the bifurcation of the internal carotid artery. The balloons were placed in the proximal end of internal carotid artery in 9 cases and in the neck of aneurysm in 3 cases. Intraoperative angiography showed that 12 aneurysms were completely occluded; 1 had severe stenosis of parent artery, and 1 had mild stenosis. Postoperative complications included cerebral infarction in 1 case, temporary diabetes insipidus in 1 case (returned to normal 1 week after operation), hemiplegia in 1 case, and epilepsy in 1 case. Glasgow Outcome Scale score at discharge showed 5 in 9 cases, 4 in 2 cases, and 3 in 1 case. The patients were followed up for 2.3 to 12 months after operation (median 7.5 months). Reexamination of CT angiography showed no recurrence of aneurysm. Glasgow Outcome Scale score was 5 in 11 cases and 4 in 1 case. Conclusions The use of balloon-assisted clipping technique in the hybrid operating room for the treatment of giant intracranial segmental aneurysms of the internal carotid artery is safe and effective, and has a good long-term outcome.

Objective To establish and evaluate a rat model of nonarteritic anterior ischemic optic neuropathy (NAION).Methods The rats were randomly divided into control group (n=13), sham laser group (n=11) and NAION group (n=23). The right eye was set as the experimental eye. NAION model was induced by directly illuminating the optic nerve (ON) of the right eye with 532 nm green laser, after intravenous infusion with the photosensitizing agent Rose Bengal. Sham laser treatment consisted of illuminating the ON region with 532 nm laser without Rose Bengal injection. Rats in control group underwent no intervention. The appearance of optic disc was observed with funduscope at 12 hours, 1, 3, 7, 28 days post-illumination. The histologic changes in the retina and ON of the NAION model were evaluated qualitatively with hematoxylin and eosin (HE) staining and transmission electron microscopy. The retrograde-labeled retinal ganglion cells (RGC) were counted on photographs taken from retinal flat mounts in a masked fashion.Results The optic disc in NAION eyes were swollen 3 days after photodynamic treatment. HE-stained longitudinal ON sections of NAION revealed vacuolar degeneration on day 3 after induction. Besides, ultrastructural study showed axonal edema and collapsed sheaths in the ischemic optic nerve at the same time point after modeling. ON edema resolved 7 days after induction. The final results revealed optic disc atrophy, extensive axonal loss, severe glial scar, and RGC death in large numbers 4 weeks after modeling. There were no aforementioned manifestations in control and sham laser group. The RGC density of the right eyes was statistically significantly lower in NAION group than that in control group and in sham laser group (t=?14.142, ?14.088;P=0.000, 0.000). The survival rate of RGC was statistically significantly lower in NAION group than in control group and in sham laser group (t=?17.048, ?16.667;P=0.000, 0.000). There was no difference of RGC density and survival rate of RGC between control and sham laser group (t=0.050, 0.348;P=0.961, 0.731).Conclusion A rat model of NAION was established successfully by photodynamic treatments with Rose Bengal, which induce optic nerve damage and RGC death.

Objective:To explore the value of 18F-FDG PET/CT radiomics in predicting the cervical lymph node metastasis in salivary gland cancer. Methods:Sixty-eight patients with salivary gland carcinoma treated in the Peking University School and Hospital of Stomatology were retrospectively studied. They were randomly divided into training group ( n=40), validation group ( n=14), and test group ( n=14). The primary tumor lesions were semi-automatically delineated on PET images as regions of interest (ROIs) and the radiomic features were extracted from ROIs. After feature selection and dimension reduction, an artificial neural network (ANN) prediction model was constructed. The prediction performance of the model was assessed using receiver operating characteristic (ROC) curves, the area under ROC curves (AUC), accuracy, sensitivity, and specificity. Moreover, the performance of various models was compared using the Delong test. Results:The radiomic model yielded an AUC of 0.88 (95% CI: 0.78-0.95), a sensitivity of 75%, specificity of 92.3%, and accuracy of 88.2%. By contrast, the combined model constructed based on the clinical node status (cN) reported by PET/CT and radiomic features yielded an AUC of 0.97 (95% CI: 0.89-0.99), a sensitivity of 87.5%, specificity of 100%, and accuracy of 97.1%. The Delong test showed that there was a statistically significant difference between the combined model and cN ( Z=2.27, P<0.05), but there was no statistically significant difference between the radiomic model and cN ( P>0.05). Conclusions:The ANN model based on 18F-FDG PET/CT radiomics combined with cN reported by PET/CT can more accurately predict cervical lymph node metastasis in patients with salivary gland carcinoma.

Objective:To summarize and evaluate the target and dose design of 125I seed brachytherapy treatment plan of pediatric borderline tumor in head neck region. Methods:Eleven patients underwent definitive 125I brachytherapy or combined with surgery in Peking University Hospital of Stomatology from January 2010 to December 2018 were retrospective analyzed. The target region was set by extending the tumor gross region by 0.5 to 1.0 cm. The prescription dose and activity ranged from 80 to 120 Gy and 18.5 MBq, respectively. The treatments were performed according to the plan under general anesthesia. Response and toxic reaction were recorded during follow-up. The preoperative and postoperative dosimetric results were compared; and the local control rate, objective response rate, complete response rate and acute toxic reaction rate were calculated. Results:There was no statistically significant difference between preoperative and postoperative dosimetric results ( P>0.05). The follow-up time ranged from 33 to 131 months, with a median of 48 months. The local control rate, objective response rate, complete response rate and acute toxic reaction rate were 100%, 100%, 71.4% and 81.8%, respectively. Conclusions:Under well-designed target and dose, 125I brachytherapy for treatment of pediatric borderline tumor in head neck region would bring ideal therapeutic and toxic outcomes, and could be regarded as a feasible therapy.