Objective To investigate the toxic effect of the carboxyl-terminal peptide of β-amyloid precursor protein (APPC31) on Neuro2a cells as well as its role in the toxic process in Neuro2a cells induced by Aβ42 in vitro.Methods The plasmid vector and the APPC31 construct were transiently transfected into Neuro2a cells respectively by lipofectamine 2000.The viability of the cells was measured by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at 48 h after transfection,and their morphocytology was observed by 4', 6-diamidino-2-phenylindole (DAPI) nucleus staining.Afterword different constructs including vector, WTAPP695, APP( D664A), the amino-terminal peptide of β-amyloid precursor protein (APP△C31) and APPC31 were transiently transfected into Neuro2a cells respectively via the same method.At 24 h after transfection Aβ42 was added into the culture medium of Neuro2a cells with the desired concentration for another 24 h for cell studies.The viabihty and morphocytology of the cells were measured by using the MTT assay and DAPI nucleus staining, respectively.Results When incubated in the absence of Aβ42, the viability of cells transfected with vector and APPC31construct were 0.81 ±0.10 and 0.88 ±0.12 respectively, and accordingly there was no significant difference between the these two groups (t = - 0.78, P = 0.48 ); meanwhile no obvious cell nuclear morphological changes of apoptosis or death occurred.However when incubated in the presence of Aβ42, the viability of cells transfected with vector, WTAPP695, APP( D664A), APP△C31 and APPC31 constructs were 0.82 ±0.01, 0.78 ±0.03, 0.55 ±0.04, 0.81 ±0.04, 0.78 ±0.02 and 0.54 ±0.02 respectively.The viability of cells transfected with WTAPP construct and APPC31 construct decreased significantly ( F = 47.53, P ＜0.05) compared with the control group, meanwhile cells displayed condensed nuclear and even nuclear fragmentation.Conclusions In vitro, over-expression of a certain level of APPC31 in Neuro2a cells fails in causing cell death, but this short peptide enhances cytotoxicity induced by Aβ42 in Neuro2a cells.Thus,these results provide the experimental basis for the further explication of the pathogenesis of Alzheimer's disease.

Objective To investigate the causes of an outbreak of healthcare-associated infection with methicillin-resist-ant Staphylococcus aureus (MRSA)in a neurosurgical intensive care unit(NSICU).Methods Epidemiological investigation on 8 patients with lower respiratory tract infection (LRTI)in a NSICU between June 15 and June 28,2104 were performed by combination methods of prospective and retrospective survey.Results The attack rate of MRSA LRTI in NSICU patients was 22.86%,a total of 16 MRSA isolates were detected from patients’clinical specimens,nasal vestibule,as well as hospital surroundings during the period,pulsed-field gel electrophoresis (PFGE)result revealed that infection outbreak was caused by two subtypes of MRSA;risk factors analysis showed that long length of stay in ICU and aspiration of spu-tum through bronchoscopy were risk factors for MRSA LRTI.Conclusion Contamination of bronchoscope was the key factor for this epidemic spread of healthcare-associated MRSA infection.

Objective To understand the effect of improving compliance rate to multidrug-resistant organism (MDRO)prevention and control measures on reducing MDRO transmission in the intensive care unit (ICU ). Methods All patients in 5 ICUs of a hospital in March-June 2014 were chosen,March 1-April 30,2014 was base-line survey stage,May 1-June 30,2014 was intervention stage (comprehensive intervention measures were taken), the implementation of patients contact isolation measures,as well as awareness of MDRO-related knowledge among health care workers(HCWs)in 5 ICUs before and after intervention were compared respectively. Results HCWs' awareness rates of MDRO transmission modes,contact isolation measures,and informing of department transfer after intervention were all higher than before intervention(100.00% vs 67.22% ,98.89% vs 61.11% ,93.33% vs 45 .56% ,respectively);except single-room isolation,compliance rates to other prevention and control measures (including doctor's advice on isolation,bedside isolation,wearing isolation gowns,adding isolation logo)were all higher than before intervention(>70% vs <50% ,all P<0.01). Detection rate of MDROs after intervention was lower than before intervention (7.16% [90/1257]vs 9.65% [117/1212],χ2= 5.00,P= 0.03). Conclusion Com-prehensive intervention measures can improve HCWs'compliance to prevention and control measures on MDROs, and reduce the transmission of MDROs.

BackgroundPrevention and intervention of procrastination in college students are of great practical significance， and studies have illustrated a pairwise correlation among mindfulness， self-control， insecure attachment and procrastination， whereas the mechanism by which insecure attachment leads to procrastination remains unclear， and the related mediation path is quite understudied. ObjectiveTo investigate the effect of insecure attachment on procrastination among college students and the pathway of mindfulness and self-control， so as to inform the design of interventions for procrastination among college students. MethodsRandom and cluster sampling method were utilized to enroll 514 college students from 4 colleges in Guangdong Province From February to April 2023. Subjects were assessed using Irrational Procrastination Scale （IPS）， Adult Attachment Scale （AAS）， Mindful Attention Awareness Scale （MAAS） and Brief Self-Control Scale （BSCS）. Pearson correlation analysis were adopted to identify the correlation among above scales， and the mediation effect was examined via Bootstrap procedure. ResultsAAS score was positively correlated with IPS score （r=0.382， P<0.01）， and negatively correlated with MAAS and BSCS scores （r=-0.242， -0.353， P<0.01）. IPS score was negatively correlated with MAAS and BSCS scores （r=-0.314， -0.682， P<0.01）. MAAS score was positively correlated with BSCS score （r=0.439， P<0.01）. Insecure attachment positively predicted procrastination （β=0.377， P<0.01）， and the prediction of procrastination by insecure attachment was mediated by self-control， with an indirect effect value of 0.163 （95% CI： 0.105~0.223）， accounting for 43.24% of the total effect value. The mindfulness and self-control exerted a chained mediation effect on the relationship between insecure attachment and procrastination， and the indirect effect value was 0.056 （95% CI： 0.028~0.089）， accounting for 14.85% of the total effect value. ConclusionInsecure attachment can influence procrastination among college students both directly and indirectly through the single mediation of self-control or the chained mediation of mindfulness and self-control. ［Funded by 2023 National College Student Innovation and Entrepreneurship Training Program （number， 202310570023）］