Finite Element Analysis on Biomechanical Properties of Traditional Trajectory and Modified Cortical Bone Trajectory / 医用生物力学

Objective To study mechanical properties of traditional trajectory (TT) and modified cortical bone trajectory (MCBT) on osteoporotic vertebrae through finite element analysis. Methods The three-dimensional model of L4 segment was established, and pedicle screw (PS) (diameter 6.0 mm, length 45 mm) and MCBT screw (diameter 4.5 mm, length 40 mm) were placed on both sides of the lumbar spine. The pull-out strength and the load-displacement ratio of screws in two different screw trajectories under up, down, left, right working conditions were analyzed, and the stability between the screw and vertebral body under osteoporotic conditions was evaluated. Results Compared with TT, the pull-out strength of MCBT screw was increased by 13.1%. Compared with PS, the load-displacement ratio of MCBT screw under up, down and left working conditions was increased by 57.2%, 32.4%, and 31.6%. Under right working condition, although the load-displacement ratio of MCBT screw was higher than that of PS, no statistical difference was found. The load-displacement ratio of vertebral body in MCBT group under lateral bending and axial rotation was significantly higher than that in TT group. The load-displacement ratio of vertebral body in MCBT group under flexion was lower than that in TT group. Although the load-displacement ratio of vertebral body in MCBT group under extension was higher that that in TT group, no statistical difference was found. Conclusions MCBT is superior to TT in pull-out strength, screw stability and vertebral body stability under lateral bending and axial rotation, but its vertebral body stability under flexion and extension was weaker than that of TT. The research findings demonstrate the superiority of MCBT under osteoporotic conditions and lay the foundation for clinical application of MCBT.

Gastrointestinal involvement of COVID-19 and potential faecal transmission of SARS-CoV-2 / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was found initially in Wuhan, China in early December 2019. The pandemic has spread to 216 countries and regions, infecting more than 23310 000 people and causing over 800 000 deaths globally by Aug. 24, 2020, according to World Health Organization (https://www.who.int/emergencies/diseases/ novel-coronavirus-2019). Fever, cough, and dyspnea are the three common symptoms of the condition, whereas the conventional transmission route for SARS-CoV-2 is through droplets entering the respiratory tract. To date, infection control measures for COVID-19 have been focusing on the involvement of the respiratory system. However, ignoring potential faecal transmission and the gastrointestinal involvement of SARS-CoV-2 may result in mistakes in attempts to control the pandemic.

Reliability and validity of Chinese version of sensory-motor function scale during awake craniotomy / 中华行为医学与脑科学杂志

Objective To translate English version of sensory-motor profile awake ( SMP-a) into Chinese version (the Chinese Version of SMP-a),and analyze the reliability and validity of the scale before and after craniotomy under awakening anesthesia. Methods Eighty-one patients whose tumors were located near or already in sensory-motor functional area were included in this study. Before and after awake cranioto-my,the Chinese version of SMP-a was used to accurately assess the sensory-motor function of each patient. Finally, the reliability and validity of the scale were analyzed by SPSS statistical software. Results Cronbach's α coefficient in the Chinese version of SMP-a was 0. 971,and Cronbach's α coefficient in the four subscales of face,hand,leg and sensation was 0. 965,0. 989,0. 981 and 0. 970,respectively. The test-retest reliability of the Chinese version of sensorimotor assessment scale was 0. 910,0. 904,0. 884,0. 898 and 0. 695 (total,face,hands,legs and sensory score respectively). The raters' consistency reliability was above 0. 949,0. 960,0. 934,0. 887 and 0. 660,respectively. The Pearson correlation coefficients of sensorimotor function score with SF-36 physiological function factors and KPS score were 0. 868 and 0. 790,respectively. Conclusion Before or after operation,the Chinese version of SMP-a has preferable reliability,internal con-sistency reliability and structural validity. It is feasible in awakening anesthesia craniotomy,and the degree of damage can be determined by repeated measurement of the sensorimotor sites that may be impaired by the patient.

The value of double contrast-enhanced ultrasound and three-dimensional contrast-enhanced ultrasound in differential diagnosis of benign and malignant gastric ulceration / 中华医学超声杂志（电子版）

Objective To investigate the value of double contrast-enhanced ultrasonography (DCEUS) in combination with three-dimension (3D) contrast-enhanced ultrasound in diagnosis of benign or malignant gastric ulceration. Methods A total of 47 patients with gastric lesions were enrolled in this study. All have the pathological results, 22 of them were benign ulceration and 25 were malignant. All patients underwent DCEUS and 3D contrast-enhanced ultrasound. On the basis of oral contrast-enhanced ultrasound agents, intravenous contrast-enhanced ultrasound agents were given at the same time. Images and data were recorded. The arrival time (AT), time to peak (TTP), infusion time (IT), baseline intensity (BI), peak intensity (PI) and enhanced intensity (EI) were calculated using the time-intensity curve (TIC). Results All benign ulcerations were imaged as small pits with slight thicken of gastric wall [(8.66±2.87) mm] using DCEUS,while malignant lesions were relatively large irregular-shape, unevenly-bottom pits with significant thicken of gastric wall [(13.98±3.63)~(20.83±3.69) mm]. 3D-DCEUS images were analyzed for gastric mucosal folds, ulceration lesions, as well as local vascularity. All ulceration lesions showed broken of gastric mucosal folds, and malignant lesion showed thickness of gastric wall as“crater”, with rich and irregular vascularity. There were no statistical differences between benign gastric ulcerations and adjacent normal gastric wall (P>0.05). Malignant gastric ulceration were compared with adjacent normal gastric wall tissue, TTP, IT and BI had no statistical differences (P>0.05), while AT, PI, and EI had statistical differences [(9.00±2.02) s vs (10.90±2.75) s, P=0.008], [(35.46±5.77) dB vs (29.73±8.72) dB, P=0.009] and [(30.76±5.76) dB vs (23.45±6.84) dB, P=0.000]. PI and EI in malignant tumors were higher than those in benign ones (P<0.05). Conclusion DCEUS could be a new method in differentiating benign and malignant gastric ulceration, which can get both the anatomy and perfusion information of gastric wall as well as lesions. 3D-DCEUS can improve the quality of the conventional ultrasound image.

Development of early myocardial perfusion in diabetic rats:the stress myocardial contrast echocardiography s tudy / 中华超声影像学杂志

Objective To investigate the development of early myocardial perfusion with myocardial contrast echocardiography (MCE) combined with dipyridamole stress echocardiography in diabetic rats . Methods The diabetes mellitus (DM) group comprised 40 male diabetic rats ,induced with streptozotocin . The control group comprised 40 normal male rats ,comparable body weights with the DM group .The DM group was divided into four subgroups (0 week ,2 weeks ,4 weeks and 8 weeks after diabetic model established) and the control group was also divided into four subgroups matched with the DM group .Each rat was performed with conventional echocardiography ,MCE at baseline and after dipyridamole stress .The reserve parameters were compared between the control group and the DM group .In addition ,the differences among four subgroups in the control group and the DM group were compared ,respectively .Results MCE demonstrated that the 4 weeks and 8 weeks DM subgroup had lower myocardial blood velocity reserve and myocardial blood flow reserve than the control subgroup .The myocardial blood volume reserve was reduced in the 8 weeks DM subgroup ,too .Conclusions The impairment of myocardial perfusion in the DM rats are detected earlier with the MCE combined with dipyridamole stress .

Mechanisms of gyrA,gyrB and efflux system jointly mediating quinolone resist-ance in clinical isolates of Pseudomonas aeruginosa / 中国感染与化疗杂志

Objective To investigate the mechanisms of both levofloxacin and ciprofloxacin resistance in clinical strains of Pseudomonas aeruginosa isolated from our hosptial.Methods Twenty P .aeruginosa isolates resistant to both levofloxacin and ciprofloxacin as tested by VITEK-2 Compact were collected.Agar dilution method was used to confirm their minimum inhibito-ry concentrations (MICs)of levofloxacin and ciprofloxacin.DNA gyrase (gyrA and gyrB )and topoisomerase IV (parC and parE)were analyzed by PCR amplification.The expression of efflux systems were analyzed by real-time RT-PCR.Results The MIC results were consistent between Agar dilution method and Vitek-2 Compact system.DNA gyrase (gyrA and gyrB )se-quencing analysis showed that the mutations were mainly frame-shifting mutation characteristic of base (C)insertion at position 941 in gyrA gene,deletion of base (A)at position 1588 in gyrB gene,and insertion of base (T)at position 1543 in gyrB gene.Insertion of base (C)at position 1895 in parE gene was identified in 3 strains.Overexpression of MexAB-OprM and MexCD-OprJ was detected by real-time RT-PCR.Conclusions The insertion and/or deletion of bases in DNA gyrase (gyrA and gyrB)genes and overproduction of MexAB-OprM and MexCD-OprJ efflux systems may contribute to the resistance to both ciprofloxacin and levofloxacin in clinical isolates of P .aeruginosa.

Application of velocity vector imaging and dobutamine stress echocardiography in evaluating the strain of left ventricular in the long axis views in diabetic patients with LVEF ＞50％ / 中华超声影像学杂志

Objective To assess the systolic strain of left ventricular(LV) in the long axis views in diabeties mellitus(DM) patients with LVEF value ＞ 50％ with velocity vector imaging (VVI) and dobutamine stress echocardiography (DSE).Methods Thirty DM patients,which were excluded from coronary artery disease,valvular heart diseases,congenital heart diseases,hypertension,and LVEF value ＞50％ by echocardiography,and 20 volunteers with age and sex matched were involved in the study.Two-dimensional VVI echocardiographic cine loops were stored at baseline and dobutamine stress in the apical four-chamber,two-chamber and long axis views of LV.The maximum long systolic velocity (Vs),strain (ε)and strain rate (SR) were obtained from sygno VVI software.Results The Vs,ε and SR decreased from basal to apical in the LV walls whether in the control group or in the DM group.At baseline,SR in 7 segments,ε in 4 segments and Vs in 3 segments in the DM group decreased significantly than those in the control group (P ＜0.05).After the maximum dobutamine stress,all parameters decreased significantly in the DM group than those in the control group (all P ＜0.05).In addition,67％ parameters in apical LV and 11％ parameters in middle LV in the DM group were lower than those in the control group.All parameters in basal LV were comparable between the two groups at baseline.Conclusions The Vs,ε and SR showed decreased tendency from basal to apical in the long axis of LV.The Vs,ε and SR impairment in the long axis of DM patients appeared first in apical tissue of LV.DSE could increase the sensitivity of VVI parameters in the earlier stage.

Evaluation of systolic function of left ventricular in the short axis views in diabetic patients with ejection fraction ＞50％ with velocity vector imaging and dobutamine stress echocardiography / 中华超声影像学杂志

Objective To evaluate the systolic function of left ventricle(LV) in the short axis views in diabetic patients with ejection fraction (EF) value ＞ 50％ with velocity vector imaging (VVI) and dobutamine stress echocardiography (DSE).Methods 30 diabetic patients,which were excluded from coronary artery disease,hypertension,valvular heart diseases,congenital heart diseases,and EF value ＞50 ％by echocardiography,and 20 volunteers with age and sex matched were involved in the study.Twodimensional VVI echocardiographic cine loops were stored at baseline and dobutamine stress (10,20,30 and 40 μg · kg-1 · min-1) in the basal,middle and apical short axis views of LV.The maximum systolic velocity (Vs),strain (ε) and strain rate (SR) were obtained from sygno VVI software.Results The Vs,ε and SR showed decrement tendency from basal to apical short axis view whether in the control group or in the DM group.At baseline,the SR in the apical view decreased significantly in the DM group than that in the control group (P ＜0.05),other parameters were comparable between the two groups.After 10 μg· kg-1 · min-1 dobutamine stress,the SR in the middle and apical views and Vs,ε in the apical view decreased significantly in the DM group than those in the control group (all P ＜ 0.05).After 20μg· kg-1 · min-1 dobutamine stress,the SR in the basal,middle and apical views and Vs,ε in the middle and apical views decreased significantly in the DM group than those in the control group (all P ＜0.05).After the maximum dobutamine stress,all parameters decreased significantly in the DM group than those in the control group (all P ＜0.05).Conclusions The systolic function impairment of DM patients appeared first in the apical tissue of LV,SR was more sensitive index than velocity arnd strain,DSE could increase the sensitivity of VVI parameters in detecting the myocardial systolic function impairment in the earlier stage.

Relationship between myocardial perfusion impairment and dysfunction in diabetic rats using myocardial contrast echocardiography and velocity vector imaging / 中华超声影像学杂志

Objective To investigate whether myocardial dysfunction and perfusion impairment had happened in diabetes mellitus(DM)rats,and to assess the relationship between them by using myocardial contrast echocardiography(MCE)and velocity vector imaging(VVI).Methods MCE and VVI were performed from the short-axis views of the mid-left ventricular level both at rest and after dipyridamole stress in control rats and DM rafs(12 weeks after induction with streptozotocin).MCE-derived myocardial blood flow(MBF)and myocardial flow reserve(MFR)and VVI-derived circumferential strain rate(SRc)and SRc reserve were obtained.Results SRc(absolute value)and MBF in the DM group were significantly lower than those in the control group at rest(P =0.03 for SRc and P =0.005 for MBF).SRc reserve and MFR in the DM group were significantly lower than those in the control group after dipyridamole stress (P =0.000 for SRc reserve and P =0.014 for MFR).There was no significant correlation between SRc and MBF at rest in the DM group(r =0.189,P =0.453).However,significant negative correlation existed between SRc reserve and MFR(r =-0.658,P =0.003).Conclusions Both myocardial systolic function and perfusion are impaired in DM rats.The decrease of MBF might not be the predominant determinant of myocardial systolic dysfunction at rest.However,the impairment of MFR could be an important contributor to the decrease of myocardial contractile reserve.

Value of velocity vector imaging and stress echocardiography in the assessment of systolic function of left ventricular in diabetic rats / 中华超声影像学杂志

Objective To investigate whether velocity vector imaging (VVI) combined with stress echocardiography could detect potential myocardial impairment of the left ventricle(LV) in diabetic rats.Methods DM rats ( n = 18,administered by STZ at 65 mg/kg) and control rats( n = 12) were performed with VVI and M-mode echocardiography both at rest and after dipyridamole stress 12 weeks later. Twodimensional echocardiographic cine loops and M-mode images of three consecutive beats were obtained from the short-axis views at the mid-LV level. The means of segmental peak systolic velocity(Vs), circumferential strain(εc) ,radial strain(εr), systolic circumferential and radial strain rate (SRc, SRr) and the percent wall thickening (WT% ,derived from M-mode) were obtained. After echocardiograms were performed,the hearts were excised and prepared for HE staining and ultrastructural observations under electron microscopy.Results At rest,only SRc in the DM group was significantly lower than that in the control group( P ＜0.05), the other parameters were statistically comparable between the two groups. After dipyridamole stress,all VVI values in the DM group were significantly lower than those in the control group ( P ＜0.05).However,there was no significant difference in WT% between the two groups either at rest or after dipyridamole stress ( P ＞0.05). Conclusions The VVI parameters combined with dipyridamole stress are more effective in evaluating potential myocardial impairment of the LV walls in diabetic rats. SRc might be more sensitive indices that can be used to detect myocardial impairment at rest.

Assessment of myocardial microcirculation in diabetic rats using myocardial contrast echocardiography / 中华超声影像学杂志

Objective To investigate whether myocardial contrast echocardiography(MCE)combined with stress echocardiography could detect myocardial microcirculation disturbance of left ventricular(LV)in diabetic rats.Methods MCE were performed at rest and after dipyridamole infusion from parasternal shortaxis views at the papillary muscle level in DM rats(n=18,12 weeks later after STZ administration)and control rats(n=12).Regions of interest(ROI)were positioned with the anterior, lateral, posterior and septum walls.Plateau intensity(PI), initial slope of the curve(β)and time to PI(TTP)were obtained from the curve and myocardial blood flow(MBF)and myocardial flow reserve(MFR)was estimated.After the performance of MCE, myocardium was prepared for γ Well counting with ~(99m)Tc-MIBI and CD31 immunohistochemistry staining.Results There was no significant difference in MBF between the ROI of anterior, lateral, septum walls beyond posterior wall in each group at rest and after stress.MCE values from anterior wall were selected as the indexes for comparisons between the two groups.The PI., MBF and MFR in the DM group were significantly lower than those in the control group at rest and after stress(all P< 0.05).The β in the DM group was significantly lower and TTP was significantly longer after dipyridamole stress(P<0.05).The nuclide intake of myocardial tissue in different walls was similar in the DM group, but theY were all lower than those in the control group(P<0.05).The capillary density decreased significantly in the DM group compared with the control group.Conclusions The PI,β,TTP,MBF and MFR derived from MCE were all sensitive parameters in detecting the microcirculation disturbances in the earlier period of DM.

Measurement and comparison of the spectral transmittance of cerinate porcelain and human enamel / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the spectral transmittance of Cerinate porcelain veneer and enamel in different color and different thickness.</p><p><b>METHODS</b>Samples of Cerinate porcelain veneers were prepared in different thickness (0.50 mm, 0.75 mm, 1.00 mm) and different Vita shade (A1, A2, A3). Enamel samples in shade A2 were made with three thickness (0.50 mm, 0.75 mm, 1.00 mm). A spectrophotometer with spectra range (380-800 nm) was employed to measure the spectral transmittance.</p><p><b>RESULTS</b>Spectral transmittance decreased with the increasing in the thickness of specimens and decreasing in the color darkness. The transmittance of Cerinate porcelain veneer material and enamel in the same color and same thickness hadn't significant difference.</p><p><b>CONCLUSION</b>The key factor to spectral transmittance of porcelain veneer materials is veneer's thickness, and the color of the materials has also some influence on it. Cerinate porcelain veneers can properly recover the transparency of teeth.</p>

Extraction of sleep structure information from heart rate variability based on spectrum analysis / 生物医学工程学杂志

In this study we made full use of the heart rate spectrum analysis to obtain the character parameters of heart rate variability related to EEG sleep phase information, and then we discarded the correlation between characteristics by employing Principal Component Analysis. Finally, by means of the decision tree based on Fisher rules, we established two full automatic models for identifying healthy people and sleep apnea hypopnea syndroma (SAHS) patients respectively. The result of experiments indicates that the model is accurate and robust.

Study of Sleep Quality in Patients with Psoriasis / 中华皮肤科杂志

Objective To explore the sleep quality in patients with psoriasis. Methods Twelve psoriatic patients and 19 normal controls were examined by means of polysomnography (PSG). Results Light sleep increased markedly, but medium and deep sleep decreased in psoriatic group. Hypopnea index, apneahypopnea index, lowest oxygen saturation in arterial blood,

A STUDY ON THE CHARACTERISTICS AND NORMAL VALUES OF VISUALLY EVOKED POTENTIALS IN FLYING CADETS / 解放军医学杂志

In order to apply the brain evoked potential (BEP) in neurological examinations and medical evaluations of flying crew (cadets), we recorded and analysed visually evoked potential (VEP) of 195 normal flying, cadets of 17-19 years of age. This report concerns mainly the basic wave form, its characteristics as well as latent period and peak-to-peak values.The results showed that chief wave group and latent period were more stable. There were no notable difference in latent periods and amplitudes between two hemispheres except P2-N2. When there was mental strain, latent period was markedly shortened. There was no notable difference in the amplitudes. While the fronto-occipital VEP phase showed difference. The mean values of latent period of P1,N1, P2, N2, P, were 90.66?23.14,125.25?28.06,184.59?32.01, 264.20?50.28,304.30?48.40 respectively, and those of peak-to-peak of N1-P2, P2-N2, N2-P3 were 10.28?4.60, 9.16?4.10, 3.05?2.26 respectively. The characteristics of VEP, the reliability of its normal values, and preliminary opinion on the applica tion of evoked potentials in aerospace medicine were discussed.