ObjectiveThis study leverages structural data from antigen-antibody complexes of the influenza A virus neuraminidase (NA) protein to investigate the spatial recognition relationship between the antigenic epitopes and antibody paratopes. MethodsStructural data on NA protein antigen-antibody complexes were comprehensively collected from the SAbDab database, and processed to obtain the amino acid sequences and spatial distribution information on antigenic epitopes and corresponding antibody paratopes. Statistical analysis was conducted on the antibody sequences, frequency of use of genes, amino acid preferences, and the lengths of complementarity determining regions (CDR). Epitope hotspots for antibody binding were analyzed, and the spatial structural similarity of antibody paratopes was calculated and subjected to clustering, which allowed for a comprehensively exploration of the spatial recognition relationship between antigenic epitopes and antibodies. The specificity of antibodies targeting different antigenic epitope clusters was further validated through bio-layer interferometry (BLI) experiments. ResultsThe collected data revealed that the antigen-antibody complex structure data of influenza A virus NA protein in SAbDab database were mainly from H3N2, H7N9 and H1N1 subtypes. The hotspot regions of antigen epitopes were primarily located around the catalytic active site. The antibodies used for structural analysis were primarily derived from human and murine sources. Among murine antibodies, the most frequently used V-J gene combination was IGHV1-12*01/IGHJ2*01, while for human antibodies, the most common combination was IGHV1-69*01/IGHJ6*01. There were significant differences in the lengths and usage preferences of heavy chain CDR amino acids between antibodies that bind within the catalytic active site and those that bind to regions outside the catalytic active site. The results revealed that structurally similar antibodies could recognize the same epitopes, indicating a specific spatial recognition between antibody and antigen epitopes. Structural overlap in the binding regions was observed for antibodies with similar paratope structures, and the competitive binding of these antibodies to the epitope was confirmed through BLI experiments. ConclusionThe antigen epitopes of NA protein mainly ditributed around the catalytic active site and its surrounding loops. Spatial complementarity and electrostatic interactions play crucial roles in the recognition and binding of antibodies to antigenic epitopes in the catalytic region. There existed a spatial recognition relationship between antigens and antibodies that was independent of the uniqueness of antibody sequences, which means that antibodies with different sequences could potentially form similar local spatial structures and recognize the same epitopes.

Aim To investigate the effect of homocys-teine(Hcy)on the permeability of pulmonary micro-vascular endothelial cells(PMVECs)and the role and mechanism of RASAL1.Methods CBS+/-mice were fed a high methionine diet(HMD)for 16 weeks to replicate an animal model of hyperhomocysteinemia(HHcy).HE staining was used to observe the changes in lung tissue structure.qRT-PCR was used to detect the levels of RASAL1 and DNMT1 mRNA in lung tis-sue.Western blot was used to detect the expression of RASAL1,DNMT1,ZO-1,and VE cadherin proteins.Methylation specific PCR was used to detect methyla-tion in the RASAL1 promoter region.PMVECs were transfected with Ad-RASAL1 to detect the expression of ZO-1 and VE cadherin.The si-DNMT1 interference fragment was transfected into PMVECs,and the ex-pression of the RASAL1 was detected by qRT-PCR and Western blot.Results Serum Hcy level of HMD mice was significantly raised,and HE staining showed severe structural disorder in lung tissue.The expres-sion of RASAL1,ZO-1,and VE cadherin was de-creased,while the expression of DNMT1 was in-creased.The degree of methylation in the RASAL1 promoter region was raised.The expression of ZO-1 and VE cadherin increased after PMVECs were trans-fected with Ad-RASAL1.After knocking down DN-MT1,RASAL1 expression was increased.Conclusion Hcy can increase the permeability of PMVECs,and its mechanism is related to the upregulation of RASAL1 methylation level.

Objective:To investigate which indicator is more advantageous when using arterial oxygen saturation(SaO2)and fingertip pulse oxygen saturation(SpO2)for blood oxygen detection in patients with hyperleukocytic acute leukemia(HAL).Methods:In this prospective research,the difference between SaO2 and SpO2 of 18 HAL patients(observation group)and 14 patients(control group),as well as the relationship between the difference and white blood cell(WBC)counts were analyzed.Results:SaO2 was lower than SpO2 in the observation group(P＜0.05),and SpO2-SaO2 difference was positively correlated with WBC counts(r=0.47).However,there was no statistical difference between SaO2 and SpO2 in the control group.SaO2 and PO2 showed a downward trend with the prolongation of detection time after arterial blood was collected in the observation group,but there was no statistical difference.There was no downward trend of SaO2 and PO2 in the control group.Conclusion:HAL patients have a phenomenon where SaO2 is lower than SpO2,that is pseudohypoxemia,and this phenomenon may be caused by excessive consumption of oxygen by the leukemia cells in vitro.SpO2 can be monitored bedside in real time and is non-invasive,it is a better way to detect the blood oxygen status of HAL patients.

Objective:To investigate the effect of feeder layer cells expressing interleukin(IL)-21 on the amplification of NK cells in vitro.Methods:The K562 cell line with IL-21 expression on its membrane was constructed by electroporation,and co-cultured with NK cells after inactivation.The proliferation of NK cells was observed.The killing function of the amplified NK cells in vitro was evaluated by the lactate dehydrogenase(LDH)and interferon-γ(IFN-y)release assay.A colorectal cancer xenograft model in NOD/SCID mice was established,and a blank control group,a NK cell group and an amplified NK cell group were set up to detect the tumor killing effect of amplified NK cells in vivo.Results:K562 cells expressing IL-21 on the membrane were successfully constructed by electroporation.After co-culturing with K562 cells expressing IL-21 on the membrane for 17 days,the NK cells increased to 700 times,which showed an enhanced amplification ability compared with control group(P＜0.001).In the tumor cell killing experiment in vitro,there was no significant difference in the killing activity on tumor cells between NK cells and amplified NK cells,and there was also no significant difference in mice in vivo.Conclusion:K562 cells expressing IL-21 on the membrane can significantly increase the amplification ability of NK cells in vitro,but do not affect the killing function of NK cells in vitro and in vivo.It can be used for the subsequent large-scale production of NK cells in vitro.

Objective:To assess the deformation of the bladder-neck opening and the impact of the bladder-neck angle(BNA)on urination in male patients by fluid-structure interaction(FSI)analysis.Methods:We established geometric models of the blad-der,prostate and urethra were established,incorporating both normal and enlarged BNAs,and assessed the effects of BNA alteration on urinary flow by FSI simulation of the flow rate and pressure of the urine within the bladder,bladder neck and urethra,and that of pros-tate displacement as well.We retrospectively analyzed the clinical data on 145 male patients from the Second Hospital of Hebei Medical University between June 2020 and June 2023,39 with acute urine retention(the AUR group)and 106 without(the non-AUR group),and evaluate the impact of BNA on urination based on the urinary flow rate and prostate volume.Results:Comparative simulation a-nalysis showed significant differences in the total urethral pressure and flow rate between the normal and enlarged BNA models(P＜0.05).The maximum prostate displacement was found at the bladder neck,with moderate displacement and unchanged urethral diame-ter in the normal BNA model,but significant displacement and a reduced urethral opening diameter in the enlarged BNA model.FSI analysis confirmed an evident impact of enlarged BNA on urination,more significant in the AUR than in the non-AUR patients(P＜0.05).The BNAs in the patients with the maximum urinary flow rate(Qmax)of＜10,10-15 or＞15 ml/s were 83.7°±2.5°,67.5°±1.8° and 65.1°±4.8° respectively,with statistically significant difference between the former one and the latter two groups(P＜0.05).The BNAs in the patients with normal prostate volume or BPH of grade Ⅰ,Ⅱ,Ⅲ or Ⅳ were 65.0°±3.7°,67.2°±3.1°,71.5°±2.0°,82.8°±3.5° and 105.8°±6.0°,respectively(P＜0.05),with statistically significant difference between BPH grades Ⅲ and Ⅳ(P＜0.05)as well as between these two and the other three groups(P＜0.05),but not among the normal prostate volume,BPH grade Ⅰ and BPH grade Ⅱ groups(P＞0.05).Spearman correlation analysis indicated that BNA was strongly correlated with total prostate volume(TPV),transition zone volume(TZV),intravesical prostatic protrusion(IPP),prostatic urethral angle(PUA),IPSS,and Qmax(P＜0.05).Conclusion:Changes in BNA affect urination and are closely associated with the se-verity of prostate hyperplasia.The BNA may be an important anatomical factor for assessing the severity of lower urinary tract symptoms in BPH patients.

Objective To design a novel oxygenator to solve the existing problems of extracorporeal membrane oxygenation(ECMO)machine in high transmembrane pressure difference,low efficiency of blood oxygen exchange and susceptibility to thrombosis.Methods The main body of the oxygenator vascular access flow field was gifted with a flat cylindrical shape.The topology of the vascular access was modeled in three dimensions,and the whole flow field was cut into a blood inlet section,an inlet buffer,a heat exchange zone,a blood oxygen exchange zone,an outlet buffer and a blood outlet section.The oxygenator was compared with Quadrox oxygenator by means of ANSYS FLUENT-based simulation and prototype experiments.Results Simulation calculations showed the oxygenator designed was comparable to the clinically used ones in general,and gained advantages in transmembrane pressure difference,blood oxygen exchange and flow uniformity.Experimental results indicated that the oxygenator behaved better than Quadrox oxygenator in transmembrane pressure difference and blood oxygen exchange.Conclusion The oxygenator has advantages in transmem-brane pressure difference,temperature change,blood oxygen ex-change and low probability of thrombosis.[Chinese Medical Equipment Journal,2024,45(3):23-28]

The risks related to the essential performance were analyzed with considerations on the concept of the essential performance in GB 9706.1-2020 Medical electrical equipment-Part 1:General requirements for basic safety and essential performance,and the determination process for the essential performance of medical electrical equipment was summarized.The essential performance of the example equipment was clarified with the semi-quantitative risk analysis,and the influences of the arrangement of the electromagnetic compatibility test on the determination of the essential performance were explored with the conducted immunity test and conventional test.References were provided for standard users to understand and determine the essential performance effectively.[Chinese Medical Equipment Journal,2024,45(11):72-76]

Objective To systematically evaluate the efficacy and safety of rituximab rapid desensitization therapy.Methods PubMed,Embase,Cochrane,Web of Science,Scopus,CNKI,Wanfang,and VIP databases were searched,and the search time frame was from the establishment of the database to February 2023.Two evaluators independently screened the literature,extracted data,and evaluated the quality of the included literature,and the resulting data were analyzed descriptively or statistically.The systematic review protocol was registered on PROSPERO(CRD:42022306557).Results Twenty-five studies(11 case reports and 14 case series)were included,with 138 patients desensitized,of whom 129 were successfully desensitized(i.e.,completed at least one target dose administration).The pretreatment regimen prior to desensitization was a combination of 2 or more of several classes of drugs,including H1 and H2 receptor antagonists,glucocorticoids,sedatives,NSAIDs,and acetaminophen,and 88%of the pretreatment regimens included H1 receptor antagonists or glucocorticoids.Sixteen studies(64.0%)reported on skin testing prior to desensitization,with positive rates of 12.50%for skin prick tests(n=16)and 49.15%for intradermal tests(n=59).Seventeen studies(68.0%)used the 3 bags-12 steps rapid desensitization protocol,the rest were for multiple desensitization methods such as 4 bags-16 steps or 2 bags-8 steps.The initial administration concentration of rituximab(i.e.,the concentration of the first desensitizing solution)was 1/10 X-1/10,000 X in most of the included studies,the first step infusion rate was 1.5-5 mL·min-1,and the total duration of single desensitization was approximately 4-10.5 h.Twenty-three studies(92%)reported the occurrence of anaphylactic reactions during patient desensitization,of which five studies had no anaphylactic reactions at the time of desensitization,and the majority of patients in the other 18 studies were able to continue to complete desensitization after being given symptomatic treatment or a modified desensitization regimen.Conclusions Current evidence suggests that rituximab rapid desensitization therapy has certain effectiveness and safety.However,there is still a lack of high-quality evidence or execution standards with strong operability and more large-sample,multicenter studies are needed to further explore the aspects of skin testing before desensitization,pretreatment,individualized desensitization steps,and management of allergic reactions during desensitization.

Objective To investigate the risk factors for bronchopulmonary dysplasia(BPD)in twin preterm infants with a gestational age of<34 weeks,and to provide a basis for early identification of BPD in twin preterm infants in clinical practice.Methods A retrospective analysis was performed for the twin preterm infants with a gestational age of<34 weeks who were admitted to 22 hospitals nationwide from January 2018 to December 2020.According to their conditions,they were divided into group A(both twins had BPD),group B(only one twin had BPD),and group C(neither twin had BPD).The risk factors for BPD in twin preterm infants were analyzed.Further analysis was conducted on group B to investigate the postnatal risk factors for BPD within twins.Results A total of 904 pairs of twins with a gestational age of<34 weeks were included in this study.The multivariate logistic regression analysis showed that compared with group C,birth weight discordance of>25%between the twins was an independent risk factor for BPD in one of the twins(OR=3.370,95%CI:1.500-7.568,P<0.05),and high gestational age at birth was a protective factor against BPD(P<0.05).The conditional logistic regression analysis of group B showed that small-for-gestational-age(SGA)birth was an independent risk factor for BPD in individual twins(OR=5.017,95%CI:1.040-24.190,P<0.05).Conclusions The development of BPD in twin preterm infants is associated with gestational age,birth weight discordance between the twins,and SGA birth.

Humans ; PPAR gamma/metabolism* ; Multiple Sclerosis ; Transcription Factors/metabolism* ; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha