Lysostaphin (Lysn) is an antibacterial metalloendopeptidase that cleaves the pentaglycin bridges in the cell wall of Staphylococci. Although many studies have demonstrated its high activity in vitro, the medical application of Lysn has been hampered by its short half-life in vivo. In order to enhance its stability in vivo without significantly suppressing the enzymatic activity, we designed and tested eight single cysteine substitutions in Lysn for covalent attachment of polyethylene glycol chains (PEGylation). The purified mutants, fully reduced by Dithiothreitol (DTT), were treated with mPEG-MAL(20 kDa). The PEG modification efficiency was above 70% as determined by reverse-phase high-pressure liquid chromatography (HPLC) analysis. The PEG-Lysn proteins were further purified by cation exchange chromatography (MacroCap SP), reaching at least 95% purity. The activities of the PEG-Lysn proteins were determined by the turbidity and minimum inhibitory concentration (MIC) assays. We found that the PEGylated V240C and T244C mutants retained about 50% of the original antibacterial activity of Lysn. Overall, this study will help develop highly stable and active PEG-Lysn to treat systemic S. aureus infections.
Amino Acid Substitution ; Lysostaphin ; chemistry ; Polyethylene Glycols ; chemistry ; Protein Engineering ; Recombinant Proteins ; chemistry ; Staphylococcus aureus

After a description of the basic situation of medical literature retrieval course for foreign undergraduates studying in Sun Yat-sen University, the problems in their teaching contents and teaching methods were pointed out with measures proposed for improving the teaching of their medical literature retrieval course.

After a description of the new connotations of information literacy education in medical undergraduates in the era of omnimedica such as visual information literacy education, media information literacy education and mobile information literacy education, new strategies were proposed for the information literacy education in medical undergraduates in the era of omnimedia, including updating teaching model, adding education contents, and improving omnimedia presentation ability.

Objective To summarize the funding of scientific research projects on obstetrics and gynecology by National Natural Science Foundation of China (NSFC) from 2007 to 2016 and to display the hotspots of scientific research on obstetrics and gynecology. Methods A systemic search was performed for the information of projects supported by NSFC from 2007 to 2016. The indicators for analysis included the number of projects, total investment, project categories, research units and research field. The research direction of each project was decided based on title, summary and key words provided by the profile of each project. Results The total investment on obstetrics and gynecology by NSFC was 23.214 million with a total of 82 projects in 2007. It increased year by year and reached the peak in 2014 (359 projects 208.990 million). The investment and number of projects remained stable after 2014. General projects (1109 projects 608.000 million) formed the majority of projects. Youth science fund projects (1035 projects 214.976 million) increased steadily and the number was nearly equal to general projects. There were only a small amount of key projects (20 projects 54.720 million) and major projects (7 projects 38.400 million). The investment varied in different research units. The greatest 10 units (less than 6% of total), including 7 comprehensive universities, 2 medical universities and 1 institute of medicine, got 1113 projects invested (43.84% of total,1113/2539). The hot areas like gynecological tumor (920 projects 350.615 million),hypertensive disorders complicating pregnancy (91 projects 37.470 million) and polycystic ovarian syndrome (77 projects 29.540 million) were more likely to receive investment, while some interdisciplinary science like maternal and child health (28 projects 12.050 million), imaging and biomedicine (37 projects 14.770 million) began to achieve attention in recent years. Conclusions The number of researches invested will be increased for the scientific research in obstetrics and gynecology especially the areas of research focus, although the amount allocated for each will be decreased relatively. Besides, multidisciplinary work will be performed so as to develop obstetrics and gynecology of China to a high level.

Objective To analyze regional left ventricular systolic function before and after percutaneous translumial coronary angioplasty(PTCA),quantitative tissue velocity imaging(QTVI)was used tO detect wall motion of left ventricule.Methods 20 patients with isolated left anterior descending coronary artery(LAD)stenosis(≥70%)and 16 normal control subjects were included in this study.QTVI was performed one day before PTCA+stent,a week and a month after successful PTCA+stent.Peak systolic myocardial velocity(Vs)were measured with QTVI at different wall segments(basal and medial segments).Results Before PTCA+stent,Vs of all segments assigned by LAD were significantly lower than those of corresponding segments in normal subjects(P＜0.01).After PTCA+stent,the above segments showed a significant improvement of Vs in a week and a month(P＜0.01).Conclusion QTVI can quantitively detect changes of myocardiac motion and real-time quantify regional left ventricular systolic function before and after PTCA.

BACKGROUND: It has been reported that the ischemia preconditioning (IPC) had credible protective efficiency on ischemic injury of the spinal cord during aorta operation, but the mechanism of the protective efficiency of IPC had not been clarified.OBJECTIVE: To study the protective effects of repetitive IPC on ischemic injury of spinal cord and its mechanism in rabbits.DESIGN: A completely randomized controlled study based on the experimental animals.SETTING: Department of anesthesiology in a university hospital.MATERIALS: The experiment was completed in the Department of Anesthesiology, Renmin Hospital, Wuhan University during September and December 2002. Twenty-four Japanese rabbits were randomly and double-blindly divided into sham-operation group, ischemia-reperfusion group and IPC group with 8 rabbits in each group.INTERVENTIONS: In sham-operation group, abdominal aorta was not clamped. Spinal cord ischemia was induced by infra-renal aortic cross-clamp for 45 minutes in ischemia-reperfusion group. Before the 45 minutes ischemia, the rabbits in the IPC group underwent four cycles of ischemia preconditioning, i.e. clamping abdominal aorta for 5 minutes then reperfusion for 5 minutes.MAIN OUTCOME MEASURES: The concentrations of calcium, magnesium, copper and zincum in spinal cord were measured in the 7th day after operation. Postoperative neurological function, EMG of rear limb, and spinal cord histopathological changes were assessed in all groups after operation.RESULTS: The concentrations of calcium and copper in spinal cord in ischemia-reperfusion group were significantly higher than those in sham-operation group( P ＜ 0. 05 or 0. 01 ), but magnesium and zincum significantly lower( P ＜ 0. 05). Compared with IPC group, calcium in ischemia-reperfusion group was significantly higher( P ＜ 0.01 ), but zincum significantly lower( P ＜ 0.01 ) . The neurological function and histopatholohical changes in ischemia-reperfusion group were much lower than those in sham-operation group and IPC group ( P ＜ 0.05 or P ＜ 0.01) . And there was significantly worse change of EMG in ischemia-repeffusion group than that in IPC group(P ＜ 0.01).CONCLUSION: Repetitive ischemic preconditioning can protect rabbit spinal cord from ischemia reperfusion injury quickly, and one possible reason for its protective effect is to maintain the balance of calcium, magnesium,copper and zincum in ischemic region.

After a description of the application of education game in literature retrieval teaching and the practical activities of information literacy education game in our library, suggestions were put forward for the problems that need to be concerned in performing information literacy education game, namely pursuing the benefits and avoi-ding the hazards, making entertainment a medium of education, rational application of small game in classroom teaching, taking immediate action, and leaving it undone as it is small.

Objective To explore the influencing factors and possible mechanism of osteonecrosis of the femoral head(ONFH)in patients with leukemia after allogeneic hematopoietic stem cell transplantation (Allo-HSCT).Methods One hundred and two patients with leukemia who received Allo-HSCT between January 2003 and October 2007 were evaluated for ONFH and graft-versus-host disease(GvHD)within 2years after transplantation,and the dosage of methylprednisolone(MP)in every patient from the first diagnosis of leukemia to 2 years after Allo-HSCT was calculated.For patients who suffered acute GvHD(aGvHD) and chronic GvHD(cGvHD),the serum leveh of soluble ligand of receptor activator of nuclear factor kappa B (sRANKL)which was index for differentiation of osteoclast(OC),tartrate-resistant acid phosphatase-5b(TRAP-5b)and C-terminal telopeptide of collagen Ⅰ(CTP-Ⅰ)which both were indexes for metabolism of OC were detected by enzyme-linked immunosorbent assay in different stages of MP dosage.According to these results.possible factors for ONFH after Allo-HSCT were analyzed.Results Seven in 102 patients after Allo-HSCT had experienced ONFH within 2 years,the incidence was 6.9%(7/102),which was not related to age,gender,types of leukemia and donor.ONFH mainly developed in patients with aGvHD and cGvHD,and the incidence could be achieved to 21.9%(7/32)which Was much higher than that in patients with no GvHD,merely aGvHD or merely cGvHD(P<0.05).In patients with aGvHD and cGvHD,the average dosage of MP in ONFH(+)was(232.7±28.6)mg/kg which was extremely higher than that in ONFH(-)(115.1±16.9)mg/kg(P<0.05).The serum levels of sRANKL,TRAP-5b and CTP-Ⅰ were also higher when ONFH happened than ahead of pretreatment and 28 days after transplantation(-)(P<0.05),and they were closely related to the dosage of MP(correlation coefficient was 0.597,0.664 and 0.682 respectively,P<0.05).Conclusions After Allo-HSCT,ONFH is related to the dosage of MP in treatment of GvHD.MP may be responsible for enhancement of OC differentiation and metabolism in leukemia patients,and ultimately induced the onset of ONFH.

Objective To evaluate the application of MSCT perfusion imaging (PI)in diagnosing solitary pulmonary nodule (SPN).Methods 60 patients with SPN diagnosed by pathology were divided into two groups.Study group (SG)included 32 patients with lung cancer,and control group (CG)included 28 patients with benign nodules.The patients of two groups underwent 64-slice spiral CT PI and routine contrast-enhanced scan (ES).PI parameters were compared between SG and CG.The diagnosis value of PI was compared with that of ES.Results Compared with CG,SG had markedly higher BV,BF,PS and lower MTT (all P <0.01).Compared with ES, PI was more sensitive in detecting lung cancer and had a higher accuracy in diagnosing SPN (P <0.01).Conclusion MSCT PI plays an important role in diagnosing SPN.

Lysostaphin is highly effective on eliminating methicillin resistant Staphylococcus aureus (MRSA). In order to achieve controlled release of lysostaphin, a biocompatible drug carrier is needed. Hydroxyapatite/chitosan (HA/CS) composites were chosen to carry lysostaphin and sample composites with different weight ratios of HA to CS, including 80/20, 70/30, 60/40, and 40/60, were prepared. Multiple analyses were performed to determine the structural and physicochemical properties of the composites, including scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. We immersed HA/CS composites loaded with 1 wt% lysostaphin to test in vitro release activity and cultured MC3T3-E1 cells to carry out biocompatibility test. The result of the release behavior of the composites revealed that the controlled release of lysostaphin from 60/40 HA/CS composites was the highest release rate of (87.4 ± 2.8)%, which lasted for 120 hours. In biocompatibility testing, MC3T3-E1 cells were able to proliferate on the surface of these composites, and the extract liquid from the composites could increase the growth of the cells. These results demonstrate the controlled release of lysostaphin from HA/CS composites and their biocompatibility, suggesting the potential application of these composites to bone injury and infection applications.