Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK:a case series

●AIM:To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty(SLAK)with corneal crosslinking(CXL)on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo.The lenticules were collected from patients undertaking small incision lenticule extraction(SMILE)for the correction of myopia.Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength.●RESULTS:All surgeries were conducted successfully with no significant complications.Their best corrected visual acuity(BCVA)ranged from 0.05 to 0.8-2 before surgery.The pre-operational total corneal thickness ranged from 345-404μm and maximum keratometry(Kmax)ranged from 50.8 to 86.3.After the combination surgery,both the corneal keratometry(range 55.9 to 92.8)and total corneal thickness(range 413-482μm)significantly increased.Four out of 5 patients had improvement of corneal biomechanical parameters(reflected by stiffness parameter A1 in Corvis ST).However,3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze.Despite the onset of corneal edema right after SLAK,the corneal topography and thickness generally stabilized after 3mo.●CONCLUSION:SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia.Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

A 3-month comparison study of subjective and objective visual quality of small incision lenticule extraction and transepithelial photorefractive keratectomy in patients with low and moderate myopia

AIM:To compare the subjective and objective visual quality between small incision lenticule extraction(SMILE)and transepithelial photorefractive keratectomy(t PRK)in patients with low and moderate myopia.METHODS:Patients undertaking SMILE or t PRK for the correction of low and moderate myopia were consecutively recruited in this prospective cohort study with a 3-month follow-up period.Objective evaluation[visual acuity test,manifest refraction,wavefront aberrations,the total cut-off value of the total modulation transfer function(MTFcut-off),and Strehl ratio(SR)]and subjective evaluation of visual quality(quality-of-life questionnaire)were conducted before surgery and at days 1,7,30,and 90 after surgery.RESULTS:A total of 47 patients(94 eyes)with SMILE and 22 patients(22 eyes)with t PRK were enrolled.The uncorrected visual acuity(UCVA)was better in SMILE patients on day 7 after surgery(1.13±0.13 vs 0.99±0.17,t=4.85,P<0.001)but was comparable at days 30 and 90.At day 90,the SMILE group had a lower spherical equivalent(SE)than the t PRK group(0.04±0.31 vs 0.19±0.43,t=2.08,P=0.042).Total higher order aberrations(HOAs)were induced in both surgical types,which were more evident in the t PRK group with 3-mm pupil diameter(0.16±0.07 vs0.11±0.05,t=4.27,P<0.001)and 5-mm pupil diameter(0.39±0.17 vs 0.36±0.11,t=2.33,P=0.022).The MTFcut-offand SR showed a trend of improvement in both SMILE and t PRK patients but were statistically better in the SMILE group with both pupil diameters.There was a significant improvement of contrast sensitivity(CS)over baseline levels at the spatial frequency of 18 cycles/degree(c/d)in the SMILE group(F=2.72,P=0.033)and at 3 c/d(F=3.03,P=0.031),12 c/d(F=3.72,P=0.013),and 18 c/d(F=4.62,P=0.004)in the t PRK group.The subjective quality of life questionnaire showed a steady improvement in the SMILE group(F=8.31,P<0.001)but not the t PRK group.CONCLUSION:SMILE and t PRK are both safe and effective ways to correct low and moderate myopia.A generally better and quicker recovery of visual quality favors the application of SMILE in qualified patients.

Collagen scaffold combined with human umbilical cord-mesenchymal stem cells transplantation for acute complete spinal cord injury

Currently, there is no effective strategy to promote functional recovery after a spinal cord injury. Collagen scaffolds can not only provide support and guidance for axonal regeneration, but can also serve as a bridge for nerve regeneration at the injury site. They can additionally be used as carriers to retain mesenchymal stem cells at the injury site to enhance their effectiveness. Hence, we hypothesized that transplanting human umbilical cord-mesenchymal stem cells on collagen scaffolds would enhance healing following acute complete spinal cord injury. Here, we test this hypothesis through animal studies and a phase I clinical trial.(1) Animal experiments: Models of completely transected spinal cord injury were established in rats and canines by microsurgery. Mesenchymal stem cells derived from neonatal umbilical cord tissue were adsorbed onto collagen scaffolds and surgically implanted at the injury site in rats and canines;the animals were observed after 1 week–6 months. The transplantation resulted in increased motor scores, enhanced amplitude and shortened latency of the motor evoked potential, and reduced injury area as measured by magnetic resonance imaging.(2) Phase I clinical trial: Forty patients with acute complete cervical injuries were enrolled at the Characteristic Medical Center of Chinese People's Armed Police Force and divided into two groups. The treatment group(n = 20) received collagen scaffolds loaded with mesenchymal stem cells derived from neonatal umbilical cordtissues;the control group(n = 20) did not receive the stem-cell loaded collagen implant. All patients were followed for 12 months. In the treatment group, the American Spinal Injury Association scores and activities of daily life scores were increased, bowel and urinary functions were recovered, and residual urine volume was reduced compared with the pre-treatment baseline. Furthermore, magnetic resonance imaging showed that new nerve fiber connections were formed, and diffusion tensor imaging showed that electrophysiological activity was recovered after the treatment. No serious complication was observed during follow-up. In contrast, the neurological functions of the patients in the control group were not improved over the follow-up period. The above data preliminarily demonstrate that the transplantation of human umbilical cord-mesenchymal stem cells on a collagen scaffold can promote the recovery of neurological function after acute spinal cord injury. In the future, these results need to be confirmed in a multicenter, randomized controlled clinical trial with a larger sample size. The clinical trial was approved by the Ethics Committee of the Characteristic Medical Center of Chinese People's Armed Police Force on February 3, 2016(approval No. PJHEC-2016-A8). All animal experiments were approved by the Ethics Committee of the Characteristic Medical Center of Chinese People's Armed Police Force on May 20, 2015(approval No. PJHEC-2015-D5).

Meta-analysis of cognitive function in Chinese first-episode schizophrenia: MATRICS Consensus Cognitive Battery (MCCB) profile of impairment

Background Compromised neurocognition is a core feature of schizophrenia. With increasing studies researching cognitive function of Chinese patients with first-episode schizophrenia (FES) using MATRICS Consensus Cognitive Battery (MCCB), it is not clear about the level and pattern of cognitive impairment among this population. Aim To provide a meta-analysis systematically analysing studies of neurocognitive function using MCCB in Chinese patients with FES. Methods An independent literature search of both Chinese and English databases up to 13 March 2019 was conducted by two reviewers. Standardised mean difference (SMD) was calculated using the random effects model to evaluate the effect size. Results 56 studies (FES=3167, healthy controls (HC)=3017) were included and analysed. No study was rated as 'high quality' according to Strengthening the Reporting of Observational Studies in Epidemiology. Compared with HCs, Chinese patients with FES showed impairment with large effect size in overall cognition (SMD=-1.60,95% Cl -1.82 to -1.38,厂=67%) and all seven cognitive domains, with the SMD ranging from -0.87 to -1.41. In nine MCCB subtests, patients with FES showed significant difference in Symbol Coding (SMD=-1.90), Trail Making Test (TMT)(SMD=-1.36), Continuous Performance Test-Identical Pairs (SMD=-1.33), Hopkins Verbal Learning Test (SMD=-1.24), Brief Visuospatial Memory Test (SMD=-1.18), Mazes (SMD=-1.16), Category Fluency (SMD=-1.01), Spatial Span (SMD=-0.69) and Mayer-Salovey-Caruso Emotional Intelligence Test (SMD=-0.38). Conclusions Our meta-analysis demonstrates that Chinese patients with FES show neurocognitive deficits across all seven MCCB cognitive domains and all nine subtests, particularly in two neurocognitive domains: speed of processing and attention/vigilance, with the least impairment shown in social cognition. Symbol Coding and TMT may be the most sensitive tests to detect cognitive deficit in Chinese patients with FES.

Collagen/heparan sulfate porous scaffolds loaded with neural stem cells improve neurological function in a rat model of traumatic brain injury

One reason for the poor therapeutic effects of stem cell transplantation in traumatic brain injury is that exogenous neural stem cells cannot effectively migrate to the local injury site,resulting in poor adhesion and proliferation of neural stem cells at the injured area.To enhance the targeted delivery of exogenous stem cells to the injury site,cell therapy combined with neural tissue engineering technology is expected to become a new strategy for treating traumatic brain injury.Collagen/heparan sulfate porous scaffolds,prepared using a freeze-drying method,have stable physical and chemical properties.These scaffolds also have good cell biocompatibility because of their high porosity,which is suitable for the proliferation and migration of neural stem cells.In the present study,collagen/heparan sulfate porous scaffolds loaded with neural stem cells were used to treat a rat model of traumatic brain injury,which was established using the controlled cortical impact method.At 2 months after the implantation of collagen/heparan sulfate porous scaffolds loaded with neural stem cells,there was significantly improved regeneration of neurons,nerve fibers,synapses,and myelin sheaths in the injured brain tissue.Furthermore,brain edema and cell apoptosis were significantly reduced,and rat motor and cognitive functions were markedly recovered.These findings suggest that the novel collagen/heparan sulfate porous scaffold loaded with neural stem cells can improve neurological function in a rat model of traumatic brain injury.This study was approved by the Institutional Ethics Committee of Characteristic Medical Center of Chinese People’s Armed Police Force,China(approval No.2017-0007.2)on February 10,2019.

Expert consensus of the Chinese Association for the Study of Pain on pain treatment with the transdermal patch

Chronic pain lasting more than 3 mo,or even several years can lead to disability.Treating chronic pain safely and effectively is a critical challenge faced by clinicians.Because administration of analgesics through oral,intravenous or intramuscular routes is not satisfactory,research toward percutaneous delivery has gained interest.The transdermal patch is one such percutaneous delivery system that can deliver drugs through the skin and capillaries at a certain rate to achieve a systemic or local therapeutic effect in the affected area.It has many advantages including ease of administration and hepatic first pass metabolism avoidance as well as controlling drug delivery,which reduces the dose frequency and side effects.If not required,then the patch can be removed from the skin immediately.The scopolamine patch was the first transdermal patch to be approved for the treatment of motion sickness by the Food and Drug Administration in 1979.From then on,the transdermal patch has been widely used to treat many diseases.To date,no guidelines or consensus are available on the use of analgesic drugs through transdermal delivery.The pain branch of the Chinese Medical Association,after meeting and discussing with experts and based on clinical evidence,developed a consensus for promoting and regulating standard use of transdermal patches containing analgesic drugs.

Neurological functional evaluation based on accurate motions in big animals with traumatic brain injury

An accurate and effective neurological evaluation is indispensable in the treatment and rehabilitation of traumatic brain injury. However,most of the existing evaluation methods in basic research and clinical practice are not objective or intuitive for assessing the neurological function of big animals, and are also difficult to use to qualify the extent of damage and recovery. In the present study, we established a big animal model of traumatic brain injury by impacting the cortical motor region of beagles. At 2 weeks after successful modeling, we detected neurological deficiencies in the animal model using a series of techniques, including three-dimensional motion capture, electromyogram and ground reaction force. These novel technologies may play an increasingly important role in the field of traumatic brain injury diagnosis and rehabilitation in the future. The experimental protocol was approved by the Animal Care and Use Committee of Logistics University of People's Armed Police Force(approval No. 2017-0006.2).

Penetration Estimation of GMA Backing Welding Based on Weld Pool Geometry Parameters

Penetration estimation is a prerequisite of the automation of backing welding based on vision sensing technology. However, the arc interference in welding process leads to the difficulties of extracting the weld pool characteristic information, which brings great challenges to the penetration estimation. At present, most researches focus on the extraction of weld pool geometry parameters, and the visual sensing systems are complex in structure and complicated in the image processing algorithms. The research of penetration estimation based on weld pool geometry parameters is still in the exploratory stage. The purpose of this paper is to research the relationship between the weld pool geometry parameters and the penetration during backing welding and to estimate penetration using the weld pool geometry parameters. A passive vision sensing test system for gas metal arc (GMA) backing welding was established. An image processing algorithm was developed to extract the weld pool geometry parameters, namely, the area, maximum width and length, half-length, length-width ratio and advancing contact angle (simplified as AWP, MWWP, MLWP, HLWP, LWR and ACA, respectively). The corresponding relationships between the weld pool geometry parameters and the penetration state were explored by analysing their changes with the welding current and speed. The distribution of the weld pool geometry parameters corresponding to penetration was determined. When the AWP of the weld pool is within a certain range and the values of LWR and ACA are close to their maximum and minimum respectively, the penetration is in good condition. A mathematical model with the weld pool geometry parameters as independent variables and the back-bead width (the indicator of the penetration state) as a dependent variable was established based on multivariable linear regression analysis, and relevant statistical tests were carried out. Multivariable linear regression equations for the weld pool geometry parameters and the back-bead width were deduced according to the variations in the current and speed, and the equations can be used to estimate the penetration of backing welding. The study provides a solution to penetration estimation of GMA backing welding based on automatic vision sensing.

Specific Targeting MRI of Chitosan Oligosaccharide Modified Fe_(3)O_(4) Nanoprobe on Macrophage and the Inhibition of Macrophage Foam­ing Induced by ox-LDL

Atherosclerosis(AS)is a primary cause of morbidity and mortality all over the world.Molecular imaging techniques can enable early localization and diagnosis of atherosclerosis plaques.Recent newly developed chitooligosaccharides(CSO)is considered to be capable of target mannose receptors on the surface of macrophages and to inhibit foam cell formation.Here we present a targeting magnetic resonance imaging(MRI)nanoprobe,which was successfully constructed with polyacrylic acid(PAA)modified nanometer iron oxide(Fe_(3)O_(4))as the core,and coating with CSO molecules,possessing the abilities of targeted MRI and specifically inhibition of the formation of foamy macrophages in the atherosclerotic process.The experimental results showed that the distributions of PAA-Fe_(3)O_(4) and CSO-PAA-Fe_(3)O_(4) were uniform and the corresponding sizes were about 5.93 nm and 8.15 nm,respectively.The Fourier transform infrared spectra(FTIR)testified the CSO was coupled with PAA-Fe_(3)O_(4) successfully.After coupled with CSO,the r1 of PAA-Fe_(3)O_(4) was increased from 5.317 mM s-1 to 6.147 mM s-1,indicating their potential as MRI contrast agent.Oil Red O staining and total cholesterols(TC)determination showed that CSO-PAA-Fe_(3)O_(4) could significantly inhibit the foaming process of RAW264.7 cells induced by oxidatively modified low density lipoprotein(ox-LDL).In vitro cellular MRI displayed that,compared with PAA-Fe_(3)O_(4),CSO-PAA-Fe_(3)O_(4) could lower the T1 relaxation time of RAW264.7 cells better.In summary,construction of CSO-PAA-Fe_(3)O_(4) nanoprobe in this study could realize the targeted MRI of macrophages and inhibition of ox-LDL induced macrophage foaming process.This will provide a new avenue in the diagnosis and treatment of AS.

An association study of HFEgene mutation with idiopathic male infertility in the Chinese Han population

Mutations in the haemochromatosis gene （HFE） influence iron status in the general population of Northern Europe, and excess iron is associated with the impairment of spermatogenesis. The aim of this study is to investigate the association between three mutations （C282Y, H63D and S65C） in the HFEgene with idiopathic male infertility in the Chinese Han population. Two groups of Chinese men were recruited： 444 infertile men （including 169 with idiopathic azoospermia） and 423 controls with proven fertility. The HFEgene was detected using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） technique. The experimental results demonstrated that no C282Y or $65C mutations were detected. Idiopathic male infertility was not significantly associated with heterozygous H63D mutation （odds ratio=O.801, 95% confidence interval=0.452-1.421, X2=0.577, P=0.448）. The H63D mutation frequency did not correlate significantly with the serum luteinizing hormone （LH）, follicle-stimulating hormone （FSH） and testosterone （T） levels in infertile men （P=0.896, P=0.404 and P=O.05, respectively）. Our data suggest that the HFEH63D mutation is not associated with idiopathic male reproductive dysfunction.

Immunocytochemical examination of PTEN and Ki-67 for endometrial carcinoma using thin-layer endometrial preparations

The current study is designed to evaluate certain immunocytochemical(ICC)biomarkers to gain a better cytodiagnosis.For this purpose,85 patients from March 2016 to March 2019 who planned to get a hysteroscopy assay were recruited.Cytological sampling was conducted by scratching the uterus cavity using SAP-1,and the samples were processed as liquid-based smears,using SurePath technology.36 patients diagnosed with EC or atypical endometrial hyperplasia were recruited in this study.33 cases were diagnosed with EC,and 3 cases were diagnosed with atypical endometrial hyperplasia,allocated with EC or precancerous lesions group.26 cases were diagnosed with benign lesions group.Among these cases,9 cases were diagnosed with endometrial simple hyperplasia,2 cases were diagnosed with complicated hyperplasia,5 cases were diagnosed with an irregular proliferation of endometrium and 10 cases were diagnosed with endometrial polyps.There were 23 cases in the healthy group.Staining in thin-layer endometrial preparations by ICC and using H-score or counting the percentage of stained cells.The presentation of PTEN in normal endometrium,benign lesions,and EC/precancerous lesions were different(p<0.01).Taking the cut-off value of 50(Youden’s index:0.698)PTEN expression for the diagnosis of EC/precancerous lesion,the sensitivity and specificity were 83.7%and 86.1%.The presentation of Ki-67 in normal endometrium,benign lesions,and EC/precancerous lesions were different(p<0.01).Taking the cut-off value of 15%(Youden’s index:0.76)Ki-67 expression for the diagnosis of EC/precancerous lesion,the sensitivity and specificity were 94.4%and 81.6%.In this study,the use of different cut-off values for Ki-67 and PTEN helped differentiate endometrial lesions.Immunocytochemistry in the ECT detection of PTEN and Ki-67 can improve the diagnostic capabilities of endometrial cancer and precancerous lesions.

Expert consensus of Chinese Association for the Study of Pain on the non-opioid analgesics for chronic musculoskeletal pain

Chronic musculoskeletal pain(CMP)is a common occurrence in clinical practice and there are a variety of options for the treatment of it.However,the pharmacological therapy is still considered to be a primary treatment.The recent years have witnessed the emergence of opioid crisis,yet there are no relevant guidelines on how to treat CMP with non-opioid analgesics properly.The Chinese Medical Association for the Study of Pain convened a panel meeting to develop clinical practice consensus for the treatment of CMP with non-opioid analgesics.The purpose of this consensus is to present the application of nonsteroidal antiinflammatory drugs,serotonin norepinephrine reuptake inhibitors,serotonin and norepinephrine reuptake inhibitors,muscle relaxants,ion channel drugs and topical drugs in CMP.

The choice of the immunosuppressant for the patients of the malignant tumors after kidney transplantation

Objective: To evaluate the efficacy and safety of the immunosuppressant treatment among 10 post-renal transplantation recipients with malignant tumors. Methods: Conversion to sirolimus (SRL) treatment was performed for 10 cases which had found malignant tumors after kidney transplantation. During the follow-up period, the recurrence and diffusion of the tumor, the renal function and rejection were monitored. Results: All these cases despite the death had been followed up for at least 1 year. 9 cases had no recurrence and diffusion. 1 case died due to the tumor diffusion 7 months after the drug conversion. 1 case suffered once acute rejection 2 months after the drug conversion. This acute rejection had been inhibited by flushing dose MP. Conclusion: As a new immunosuppressant, SRL not only can prevent the generation of AR, but inhibit proliferation and development of malignant tumors in kidney transplantation recipients as well.

Deep-sea rock mechanics and mining technology:State of the art and perspectives

The review covers the development and the state of the art in deep-sea mining rock mechanics,equipment and challenges.It begins by introducing the significance of deep-sea mining,the types and geographical distribution of deep-sea resources.Section 2 reviews the mechanical properties and fracture mechanism of seabed and related continental rocks,which contributes to the advancement of relevant technologies and theories.Deep-sea mining systems developed by coastal countries are presented in Section 3.Seabed mineral collection systems are critically assessed in Section 4.Subsea mining vehicle is reviewed by walking mechanism and controlling system in Section 5.In Section 6,the development of subsea lifting system is detailed by dividing it into hydraulic and pneumatic lifting modes,and some technical problems in the lifting system are described.An in-depth description of surface support systems is presented in Section 7,which includes the deep-sea mining ship,dynamic positioning system,heave compensation system,launch and retrieval system,mineral disposing system as well as the storage and transferring systems.Section 8 discusses the challenges in the deep-sea mining,in terms of natural occurrence conditions,international legal framework and cooperative mining,environmental protection and economic benefits,etc.Finally,a brief summary and some aspects of prospective research are presented in Section 9.

3D printed fiber-optic nanomechanical bioprobe

Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.

Clinical Analysis of Embryonic Posterior Cerebral Artery

Objective:To understand the clinical characteristics of patients with embryonic posterior cerebral artery and its correlation with abnormal vascular development.Methods:The clinical data of 396 patients with embryonic posterior cerebral artery confirmed by magnetic resonance angiography(MRA)and computed tomography angiography(CTA)were analyzed.Results:Two-hundred patients had clinical manifestations of posterior circulation ischemia,including recurrent dizziness,vertigo,and tinnitus;45 had headaches,97 had limb weakness,and 16 patients had syncope or impaired consciousness.Seventy-six patients with circulatory infarction were admitted to the hospital.There were 251 patients with history of hypertension,74 with diabetes,113 with hyperlipidemia,13 with dominant vertebral artery,10 with intracranial aneurysm,and 19 with absence of A1 segment of the anterior cerebral artery(considering developmental variation).Conclusion:Embryonic posterior cerebral artery develops abnormally during the embryonic period,often accompanied by abnormal vascular access.Due to abnormal hemodynamics,the incidence of posterior circulation ischemia,aneurysm,and infarction increases in such patients.

工训大赛牵引下的虚拟仿真教学模式探索

教育部高等教育司主办的全国大学生工程训练综合能力竞赛,是面向全国在校学生开展科技创新工程实践活动的全国性大赛。通过深入分析大赛工程场景数字化赛项与创新实践能力培养的关系,文章提出“虚实结合,以赛促教,以赛促改”的创新实践能力培养模式。针对此培养模式,研究者构建以工程基础认知、虚拟仿真实训、生产现场操作三个训练层次为核心的虚拟仿真教学体系,并详细阐述体系中各类课程与工训大赛深度融合而进行的改革与建设。以基于虚拟现实技术的大型电动机轴承更换游戏的开发为实例,文章验证工训大赛牵引下的虚拟仿真教学模式的具体实施及效果。研究结果表明,大赛牵引下的虚拟仿真教学模式对提升学生的创新实践能力,以及促进工程训练中心的建设,都有积极作用。

离心式风机机架振动分析及减振试验

机架作为离心式风机的主体承载连接部件,其振动特性的优劣将直接影响风机的稳定性和可靠性。以某型号离心式风机机架为研究对象,进行有限元模态分析得出其固有频率和振型,通过开展模态试验得出机架共振频率,验证有限元分析结果的正确性。然后对机架进行谐响应分析和加速度响应试验并获得振动最大位置,在振动最大位置添加固接横梁,通过对机架进行改进前后的加速度响应测试并对试验结果进行比较,进而验证改进的有效性。研究结果为风机的后续设计及改进提供了有效参考基础。

Acute kidney injury in acute-on-chronic liver failure is different from in decompensated cirrhosis

AIM To evaluate the differences in acute kidney injury(AKI) between acute-on-chronic liver failure(ACLF) and decompensated cirrhosis(DC) patients. METHODS During the period from December 2015 to July 2017, 280 patients with hepatitis B virus(HBV)-related ACLF(HBV-ACLF) and 132 patients with HBV-related DC(HBV-DC) who were admitted to our center were recruited consecutively into an observational study. Urine specimens were collected from all subjects and the levels of five urinary tubular injury biomarkers were detected,including neutrophil gelatinase-associated lipocalin(NGAL), interleukin-18(IL-18), liver-type fatty acid binding protein(L-FABP), cystatin C(CysC), and kidney injury molecule-1(KIM-1). Simultaneously, the patient demographics, occurrence and progression of AKI, and response to terlipressin therapy were recorded. All patients were followed up for 3 mo or until death after enrollment. RESULTS AKI occurred in 71 and 28 of HBV-ACLF and HBV-DC patients, respectively(25.4% vs 21.2%, P = 0.358). Among all patients, the levels of four urinary biomarkers(NGAL, CysC, L-FABP, IL-18) were significantly elevated in patients with HBV-ACLF and AKI(ACLF-AKI), compared with that in patients with HBV-DC and AKI(DC-AKI) or those without AKI. There was a higher proportion of patients with AKI progression in ACLF-AKI patients than in DC-AKI patients(49.3% vs 17.9%, P = 0.013). Fortythree patients with ACLF-AKI and 19 patients with DC-AKI were treated with terlipressin. The response rate of ACLFAKI patients was significantly lower than that of patients with DC-AKI(32.6% vs 57.9%, P = 0.018). Furthermore, patients with ACLF-AKI had the lowest 90 d survival rates among all groups(P < 0.001).CONCLUSION AKI in ACLF patients is more likely associated with structural kidney injury, and is more progressive, with a poorer response to terlipressin treatment and a worse prognosis than that in DC patients.

Three-dimensional bioprinting collagen/silk fibroin scaffold combined with neural stem cells promotes nerve regeneration after spinal cord injury

Many studies have shown that bio-scaffolds have important value for promoting axonal regeneration of injured spinal cord.Indeed,cell transplantation and bio-scaffold implantation are considered to be effective methods for neural regeneration.This study was designed to fabricate a type of three-dimensional collagen/silk fibroin scaffold (3D-CF) with cavities that simulate the anatomy of normal spinal cord.This scaffold allows cell growth in vitro and in vivo.To observe the effects of combined transplantation of neural stem cells (NSCs) and 3D-CF on the repair of spinal cord injury.Forty Sprague-Dawley rats were divided into four groups: sham (only laminectomy was performed),spinal cord injury (transection injury of T10 spinal cord without any transplantation),3D-CF (3D scaffold was transplanted into the local injured cavity),and 3D-CF + NSCs (3D scaffold co-cultured with NSCs was transplanted into the local injured cavity.Neuroelectrophysiology,imaging,hematoxylin-eosin staining,argentaffin staining,immunofluorescence staining,and western blot assay were performed.Apart from the sham group,neurological scores were significantly higher in the 3D-CF + NSCs group compared with other groups.Moreover,latency of the 3D-CF + NSCs group was significantly reduced,while the amplitude was significantly increased in motor evoked potential tests.The results of magnetic resonance imaging and diffusion tensor imaging showed that both spinal cord continuity and the filling of injury cavity were the best in the 3D-CF + NSCs group.Moreover,regenerative axons were abundant and glial scarring was reduced in the 3D-CF + NSCs group compared with other groups.These results confirm that implantation of 3D-CF combined with NSCs can promote the repair of injured spinal cord.This study was approved by the Institutional Animal Care and Use Committee of People’s Armed Police Force Medical Center in 2017 (approval No.2017-0007.2).