Structural basis of membrane skeleton organization in red blood cells.

The spectrin-based membrane skeleton is a ubiquitous membrane-associated two-dimensional cytoskeleton underneath the lipid membrane of metazoan cells. Mutations of skeleton proteins impair the mechanical strength and functions of the membrane, leading to several different types of human diseases. Here, we report the cryo-EM structures of the native spectrin-actin junctional complex (from porcine erythrocytes), which is a specialized short F-actin acting as the central organizational unit of the membrane skeleton. While an α-/ß-adducin hetero-tetramer binds to the barbed end of F-actin as a flexible cap, tropomodulin and SH3BGRL2 together create an absolute cap at the pointed end. The junctional complex is strengthened by ring-like structures of dematin in the middle actin layers and by patterned periodic interactions with tropomyosin over its entire length. This work serves as a structural framework for understanding the assembly and dynamics of membrane skeleton and offers insights into mechanisms of various ubiquitous F-actin-binding factors in other F-actin systems.

Cryo-EM Structure and Assembly of an Extracellular Contractile Injection System.

Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC) represents one group of extracellular CISs that are present in both bacteria and archaea. Here, we report the cryo-EM structure of an intact PVC from P. asymbiotica. This over 10-MDa device resembles a simplified T4 phage tail, containing a hexagonal baseplate complex with six fibers and a capped 117-nanometer sheath-tube trunk. One distinct feature of the PVC is the presence of three variants for both tube and sheath proteins, indicating a functional specialization of them during evolution. The terminal hexameric cap docks onto the topmost layer of the inner tube and locks the outer sheath in pre-contraction state with six stretching arms. Our results on the PVC provide a framework for understanding the general mechanism of widespread CISs and pave the way for using them as delivery tools in biological or therapeutic applications.

Structure of a Pancreatic ATP-Sensitive Potassium Channel.

ATP-sensitive potassium channels (KATP) couple intracellular ATP levels with membrane excitability. These channels play crucial roles in many essential physiological processes and have been implicated extensively in a spectrum of metabolic diseases and disorders. To gain insight into the mechanism of KATP, we elucidated the structure of a hetero-octameric pancreatic KATP channel in complex with a non-competitive inhibitor glibenclamide by single-particle cryoelectron microscopy to 5.6-Å resolution. The structure shows that four SUR1 regulatory subunits locate peripherally and dock onto the central Kir6.2 channel tetramer through the SUR1 TMD0-L0 fragment. Glibenclamide-bound SUR1 uses TMD0-L0 fragment to stabilize Kir6.2 channel in a closed conformation. In another structural population, a putative co-purified phosphatidylinositol 4,5-bisphosphate (PIP2) molecule uncouples Kir6.2 from glibenclamide-bound SUR1. These structural observations suggest a molecular mechanism for KATP regulation by anti-diabetic sulfonylurea drugs, intracellular adenosine nucleotide concentrations, and PIP2 lipid.

Structural insights into the assembly and mechanism of mpox virus DNA polymerase complex F8-A22-E4-H5.

The DNA replication of mpox virus is performed by the viral polymerase F8 and also requires other viral factors, including processivity factor A22, uracil DNA glycosylase E4, and phosphoprotein H5. However, the molecular roles of these viral factors remain unclear. Here, we characterize the structures of F8-A22-E4 and F8-A22-E4-H5 complexes in the presence of different primer-template DNA substrates. E4 is located upstream of F8 on the template single-stranded DNA (ssDNA) and is catalytically active, highlighting a functional coupling between DNA base-excision repair and DNA synthesis. Moreover, H5, in the form of tetramer, binds to the double-stranded DNA (dsDNA) region downstream of F8 in a similar position as PCNA (proliferating cell nuclear antigen) does in eukaryotic polymerase complexes. Omission of H5 or disruption of its DNA interaction showed a reduced synthesis of full-length DNA products. These structures provide snapshots for the working cycle of the polymerase and generate insights into the mechanisms of these essential factors in viral DNA replication.

Parental histone transfer caught at the replication fork.

In eukaryotes, DNA compacts into chromatin through nucleosomes1,2. Replication of the eukaryotic genome must be coupled to the transmission of the epigenome encoded in the chromatin3,4. Here we report cryo-electron microscopy structures of yeast (Saccharomyces cerevisiae) replisomes associated with the FACT (facilitates chromatin transactions) complex (comprising Spt16 and Pob3) and an evicted histone hexamer. In these structures, FACT is positioned at the front end of the replisome by engaging with the parental DNA duplex to capture the histones through the middle domain and the acidic carboxyl-terminal domain of Spt16. The H2A-H2B dimer chaperoned by the carboxyl-terminal domain of Spt16 is stably tethered to the H3-H4 tetramer, while the vacant H2A-H2B site is occupied by the histone-binding domain of Mcm2. The Mcm2 histone-binding domain wraps around the DNA-binding surface of one H3-H4 dimer and extends across the tetramerization interface of the H3-H4 tetramer to the binding site of Spt16 middle domain before becoming disordered. This arrangement leaves the remaining DNA-binding surface of the other H3-H4 dimer exposed to additional interactions for further processing. The Mcm2 histone-binding domain and its downstream linker region are nested on top of Tof1, relocating the parental histones to the replisome front for transfer to the newly synthesized lagging-strand DNA. Our findings offer crucial structural insights into the mechanism of replication-coupled histone recycling for maintaining epigenetic inheritance.

Target RNA activates the protease activity of Craspase to confer antiviral defense.

In the type III-E CRISPR-Cas system, a Cas effector (gRAMP) is associated with a TPR-CHAT to form Craspase (CRISPR-guided caspase). However, both the structural features of gRAMP and the immunity mechanism remain unknown for this system. Here, we report structures of gRAMP-crRNA and gRAMP:cRNA:target RNA as well as structures of Craspase and Craspase complexed with cognate target RNA (CTR) or non-cognate target RNA (NTR). Importantly, the 3' anti-tag region of NTR and CTR binds at two distinct channels in Craspase, and CTR with a non-complementary 3' anti-tag induces a marked conformational change of the TPR-CHAT, which allosterically activates its protease activity to cleave an ancillary protein Csx30. This cleavage then triggers an abortive infection as the antiviral strategy of the type III-E system. Together, our study provides crucial insights into both the catalytic mechanism of the gRAMP and the immunity mechanism of the type III-E system.

Comprehensive structural characterization of the human AAA+ disaggregase CLPB in the apo- and substrate-bound states reveals a unique mode of action driven by oligomerization.

The human AAA+ ATPase CLPB (SKD3) is a protein disaggregase in the mitochondrial intermembrane space (IMS) and functions to promote the solubilization of various mitochondrial proteins. Loss-of-function CLPB mutations are associated with a few human diseases with neutropenia and neurological disorders. Unlike canonical AAA+ proteins, CLPB contains a unique ankyrin repeat domain (ANK) at its N-terminus. How CLPB functions as a disaggregase and the role of its ANK domain are currently unclear. Herein, we report a comprehensive structural characterization of human CLPB in both the apo- and substrate-bound states. CLPB assembles into homo-tetradecamers in apo-state and is remodeled into homo-dodecamers upon substrate binding. Conserved pore-loops (PLs) on the ATPase domains form a spiral staircase to grip and translocate the substrate in a step-size of 2 amino acid residues. The ANK domain is not only responsible for maintaining the higher-order assembly but also essential for the disaggregase activity. Interactome analysis suggests that the ANK domain may directly interact with a variety of mitochondrial substrates. These results reveal unique properties of CLPB as a general disaggregase in mitochondria and highlight its potential as a target for the treatment of various mitochondria-related diseases.

UBQLN2 and HSP70 participate in Parkin-mediated mitophagy by facilitating outer mitochondrial membrane rupture.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two aging-related neurodegenerative diseases that share common key features, including aggregation of pathogenic proteins, dysfunction of mitochondria, and impairment of autophagy. Mutations in ubiquilin 2 (UBQLN2), a shuttle protein in the ubiquitin-proteasome system (UPS), can cause ALS/FTD, but the mechanism underlying UBQLN2-mediated pathogenesis is still uncertain. Recent studies indicate that mitophagy, a selective form of autophagy which is crucial for mitochondrial quality control, is tightly associated with neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and ALS. In this study, we show that after Parkin-dependent ubiquitination of damaged mitochondria, UBQLN2 is recruited to poly-ubiquitinated mitochondria through the UBA domain. UBQLN2 cooperates with the chaperone HSP70 to promote UPS-driven degradation of outer mitochondrial membrane (OMM) proteins. The resulting rupture of the OMM triggers the autophagosomal recognition of the inner mitochondrial membrane receptor PHB2. UBQLN2 is required for Parkin-mediated mitophagy and neuronal survival upon mitochondrial damage, and the ALS/FTD pathogenic mutations in UBQLN2 impair mitophagy in primary cultured neurons. Taken together, our findings link dysfunctional mitophagy to UBQLN2-mediated neurodegeneration.

Structural basis of assembly of the human T cell receptor-CD3 complex.

The αß T cell receptor (TCR), in association with the CD3γε-CD3δε-CD3ζζ signalling hexamer, is the primary determinant of T cell development and activation, and of immune responses to foreign antigens. The mechanism of assembly of the TCR-CD3 complex remains unknown. Here we report a cryo-electron microscopy structure of human TCRαß in complex with the CD3 hexamer at 3.7 Å resolution. The structure contains the complete extracellular domains and all the transmembrane helices of TCR-CD3. The octameric TCR-CD3 complex is assembled with 1:1:1:1 stoichiometry of TCRαß:CD3γε:CD3δε:CD3ζζ. Assembly of the extracellular domains of TCR-CD3 is mediated by the constant domains and connecting peptides of TCRαß that pack against CD3γε-CD3δε, forming a trimer-like structure proximal to the plasma membrane. The transmembrane segment of the CD3 complex adopts a barrel-like structure formed by interaction of the two transmembrane helices of CD3ζζ with those of CD3γε and CD3δε. Insertion of the transmembrane helices of TCRαß into the barrel-like structure via both hydrophobic and ionic interactions results in transmembrane assembly of the TCR-CD3 complex. Together, our data reveal the structural basis for TCR-CD3 complex assembly, providing clues to TCR triggering and a foundation for rational design of immunotherapies that target the complex.

Unique Roles of the Non-identical MCM Subunits in DNA Replication Licensing.

A family of six homologous subunits, Mcm2, -3, -4, -5, -6, and -7, each with its own unique features, forms the catalytic core of the eukaryotic replicative helicase. The necessity of six similar but non-identical subunits has been a mystery since its initial discovery. Recent cryo-EM structures of the Mcm2-7 (MCM) double hexamer, its precursors, and the origin recognition complex (ORC)-Cdc6-Cdt1-Mcm2-7 (OCCM) intermediate showed that each of these subunits plays a distinct role in orchestrating the assembly of the pre-replication complex (pre-RC) by ORC-Cdc6 and Cdt1.

ApoE4 dysregulation incites depressive symptoms and mitochondrial impairments in mice.

Apolipoprotein E4 (ApoE4) is involved in the stress-response processes and is hypothesized to be a risk factor for depression by means of mitochondrial dysfunction. However, their exact roles and underlying mechanisms are largely unknown. ApoE4 transgenic mice (B6. Cg-ApoEtm1Unc Cdh18Tg( GFAP-APOE i4)1Hol /J) were subjected to stress (lipopolysaccharides, LPS) to elucidate the aetiology of ApoE4-induced depression. LPS treatment significantly aggravated depression-like behaviours, concurrent with neuroinflammation and impaired mitochondrial changes, and melatonin/Urolithin A (UA) + 5-aminoimidazole-4-carboxamide 1-ß-D-ribofuranoside (AICAR) reversed these effects in ApoE4 mice. Concurrently, ApoE4 mice exhibited mitophagy deficits, which could be further exacerbated by LPS stimulation, as demonstrated by reduced Atg5, Beclin-1 and Parkin levels, while PINK1 levels were increased. However, these changes were reversed by melatonin treatment. Additionally, proteomic profiling suggested mitochondria-related signalling and network changes in ApoE4 mice, which may underlie the exaggerated response to LPS. Furthermore, HEK 293T cells transfected with ApoE4 showed mitochondria-associated protein and mitophagy defects, including PGC-1α, TFAM, p-AMPKα, PINK1 and LC3B impairments. Additionally, it aggravates mitochondrial impairment (particularly mitophagy), which can be attenuated by triggering autophagy. Collectively, ApoE4 dysregulation enhanced depressive behaviour upon LPS stimulation.

Zymograph profiling reveals a divergent evolution of sirtuin that may originate from class III enzymes.

Sirtuins are a group of NAD+-dependent deacylases that conserved in three domains of life and comprehensively involved in the regulation of gene transcription, chromosome segregation, RNA splicing, apoptosis, and aging. Previous studies in mammalian cells have revealed that sirtuins not only exist as multiple copies, but also show distinct deacylase activities in addition to deacetylation. However, the understanding of sirtuin zymographs in other organisms with respect to molecular evolution remains at an early stage. Here, we systematically analyze the sirtuin activities in representative species from archaea, bacteria, and eukaryotes, using both the HPLC assay and a 7-amino-4-methylcoumarin-based fluorogenic method. Global profiling suggests that the deacylase activities of sirtuins could be divided into three categories and reveals undifferentiated zymographs of class III sirtuins, especially for those from bacteria and archaea. Nevertheless, initial differentiation of enzymatic activity was also observed for the class III sirtuins at both paralog and ortholog levels. Further phylogenetic analyses support a divergent evolution of sirtuin that may originate from class III sirtuins. Together, this work demonstrates a comprehensive panorama of sirtuin zymographs and provides new insights into the cellular specific regulation and molecular evolution of sirtuins.

Apigenin intervenes in liver fibrosis by regulating PKM2-HIF-1α mediated oxidative stress.

Apigenin (API) is a natural flavonoid compound with antioxidant, anti fibrotic, anti-inflammatory and other effects, but there is limited research on the effect of API on liver fibrosis. This study aims to explore the effect and potential mechanism of API on liver fibrosis induced by CCl4 in mice. The results indicate that API reduces oxidative stress levels, inhibits hepatic stellate cell (HSC) activation, and exerts anti liver fibrosis effects by regulating the PKM2-HIF-1α pathway. We observed that API alleviated liver tissue pathological damage and collagen deposition in CCl4 induced mouse liver fibrosis model, promoting the recovery of liver function in mice with liver fibrosis. In addition, the API inhibits the transition of Pyruvate kinase isozyme type M2 (PKM2) from dimer to tetramer formation by regulating the EGFR-MEK1/2-ERK1/2 pathway, thereby preventing dimer from entering the nucleus and blocking PKM2-HIF-1α access. This change leads to a decrease in malondialdehyde (MDA) and Catalase (CAT) levels and an increase in glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) levels, as well as total antioxidant capacity (T-AOC) in the liver of liver fibrosis mice. At the same time, API downregulated the expression of α-smooth muscle actin (α-SMA), Vimentin and Desmin in the liver tissue of mice with liver fibrosis, inhibited the activation of HSC, and reduced collagen deposition. These results indicate that API can inhibit HSC activation and alleviate CCl4 induced liver fibrosis by inhibiting the PKM2-HIF-1α pathway and reducing oxidative stress, laying an important foundation for the development and clinical application of API as a novel drug for treating liver fibrosis.

Aqueous humor proteomics analyzed by bioinformatics and machine learning in PDR cases versus controls.

BACKGROUND: To comprehend the complexities of pathophysiological mechanisms and molecular events that contribute to proliferative diabetic retinopathy (PDR) and evaluate the diagnostic value of aqueous humor (AH) in monitoring the onset of PDR. METHODS: A cohort containing 16 PDR and 10 cataract patients and another validation cohort containing 8 PDR and 4 cataract patients were studied. AH was collected and subjected to proteomics analyses. Bioinformatics analysis and a machine learning-based pipeline called inference of biomolecular combinations with minimal bias were used to explore the functional relevance, hub proteins, and biomarkers. RESULTS: Deep profiling of AH proteomes revealed several insights. First, the combination of SIAE, SEMA7A, GNS, and IGKV3D-15 and the combination of ATP6AP1, SPARCL1, and SERPINA7 could serve as surrogate protein biomarkers for monitoring PDR progression. Second, ALB, FN1, ACTB, SERPINA1, C3, and VTN acted as hub proteins in the profiling of AH proteomes. SERPINA1 was the protein with the highest correlation coefficient not only for BCVA but also for the duration of diabetes. Third, "Complement and coagulation cascades" was an important pathway for PDR development. CONCLUSIONS: AH proteomics provides stable and accurate biomarkers for early warning and diagnosis of PDR. This study provides a deep understanding of the molecular mechanisms of PDR and a rich resource for optimizing PDR management.

Esketamine induces apoptosis of nasopharyngeal carcinoma cells through the PERK/CHOP pathway.

Nasopharyngeal carcinoma, a malignant tumor prevalent in southeast Asia and north Africa, still lacks effective treatment. Esketamine, an N-methyl-D-aspartatic acid (NMDA) receptor (NMDAR) antagonist, is widely used in clinical anesthesia. Emerging evidence suggests that esketamine plays an important role in inhibiting tumor cell activity. However, the underlying mechanisms of esketamine on nasopharyngeal carcinoma remain unknown. In this study, we found that esketamine inhibited the proliferation and migration of nasopharyngeal carcinoma cells. Mechanically, transcriptome sequencing and subsequent verification experiments revealed that esketamine promoted the apoptosis of nasopharyngeal carcinoma cells through endoplasmic reticulum stress PERK/ATF4/CHOP signaling pathway mediated by NMDAR. Additionally, when combined with esketamine, the inhibitory effect of cisplatin on the proliferation of nasopharyngeal carcinoma cells was significantly enhanced. These findings provide new insights into future anti-nasopharyngeal carcinoma clinical strategies via targeting the NMDAR/PERK/CHOP axis alone or in combination with cisplatin.

Signature construction and molecular subtype identification based on liver-specific genes for prediction of prognosis, immune activity, and anti-cancer drug sensitivity in hepatocellular carcinoma.

BACKGROUND: Liver specific genes (LSGs) are crucial for hepatocyte differentiation and maintaining normal liver function. A deep understanding of LSGs and their heterogeneity in hepatocellular carcinoma (HCC) is necessary to provide clues for HCC diagnosis, prognosis, and treatment. METHODS: The bulk and single-cell RNA-seq data of HCC were downloaded from TCGA, ICGC, and GEO databases. Through unsupervised cluster analysis, LSGs-based HCC subtypes were identified in TCGA-HCC samples. The prognostic effects of the subtypes were investigated with survival analyses. With GSVA and Wilcoxon test, the LSGs score, stemness score, aging score, immune score and stromal score of the samples were estimated and compared. The HCC subtype-specific genes were identified. The subtypes and their differences were validated in ICGC-HCC samples. LASSO regression analysis was used for key gene selection and risk model construction for HCC overall survival. The model performance was estimated and validated. The key genes were validated for their heterogeneities in HCC cell lines with quantitative real-time PCR and at single-cell level. Their dysregulations were investigated at protein level. Their correlations with HCC response to anti-cancer drugs were estimated in HCC cell lines. RESULTS: We identified three LSGs-based HCC subtypes with different prognosis, tumor stemness, and aging level. The C1 subtype with low LSGs score and high immune score presented a poor survival, while the C2 subtype with high LSGs score and immune score indicated an enduring survival. Although no significant survival difference between C2 and C3 HCCs was shown, the C2 HCCs presented higher immune score and stroma score. The HCC subtypes and their differences were confirmed in ICGC-HCC dataset. A five-gene prognostic signature for HCC survival was constructed. Its good performance was shown in both the training and validation datasets. The five genes presented significant heterogeneities in different HCC cell lines and hepatocyte subclusters. Their dysregulations were confirmed at protein level. Furthermore, their significant associations with HCC sensitivities to anti-cancer drugs were shown. CONCLUSIONS: LSGs-based HCC subtype classification and the five-gene risk model might provide useful clues not only for HCC stratification and risk prediction, but also for the development of more personalized therapies for effective HCC treatment.

Calcitonin gene-related peptide: a possible biomarker in migraine patients with patent foramen ovale.

BACKGROUND: Serum CGRP has been found to increase during migraine attack. However, whether CGRP can identify MA with PFO subtypes in MA remains unknown. This study aimed to investigate the differential expression of calcitonin gene-related peptide (CGRP) between migraine (MA) patients with and without patent foramen ovale (PFO), and to evaluate the predictive value of CGRP for MA with PFO. METHODS: A total of 153 patients with MA, 51 patients with PFO and 102 patients without. Venous blood was drawn and HIT-6 score was calculated during the onset of MA, and blood routine, inflammatory indexes and serum CGRP were detected. The differences in serum markers and HIT-6 scores were compared between the two groups, and the risk factors of MA with PFO were determined by univariate and multivariate logistics regression. Furthermore, the correlation between CGRP level with right-to-left shunt (RLS) grades and headache impact test-6 (HIT-6) score in MA patients with PFO were assessed. Independent risk factors were screened out by multivariate Logistic regression analysis. We used the receiver operating characteristic (ROC) curve to analyze the diagnostic value of these risk factors in MA complicated with PFO. RESULTS: The serum CGRP level and HIT-6 scores in the MA with PFO group were significantly higher than those in the MA group (P < 0.001). Multivariate regression analysis showed that CGRP was an independent risk factor for MA with PFO (OR = 1.698, 95% CI = 1.325-2.179, P < 0.001). CGRP values ​​increased with the increase of RLS grade(Spearmen rho = 0.703, P < 0.001). Furthermore, a positive correlation between CGRP and HIT-6 scores was found (Spearmen rho = 0.227; P = 0.016). ROC curve showed that the optimal cut-off value for diagnosing MA with PFO was 79 pg/mL, the area under the curve (AUC) for predicting MA with PFO was 0.845, with 72.55% sensitivity and 78.43% specificity. CONCLUSIONS: MA patients with PFO have higher serum CGRP level. elevated CGRP concentration was associated with higher RLS grade and increased HIT-6 score. Higher serum CGRP level has certain clinical value in predicting PFO in MA patients. TRIAL REGISTRATION: This study was approved by the Ethics Committee of Zhuhai Hospital of Integrated Traditional Chinese and Western Medicine (Ethics batch number: 20,201,215,005).

Structure of the origin recognition complex bound to DNA replication origin.

The six-subunit origin recognition complex (ORC) binds to DNA to mark the site for the initiation of replication in eukaryotes. Here we report a 3 Å cryo-electron microscopy structure of the Saccharomyces cerevisiae ORC bound to a 72-base-pair origin DNA sequence that contains the ARS consensus sequence (ACS) and the B1 element. The ORC encircles DNA through extensive interactions with both phosphate backbone and bases, and bends DNA at the ACS and B1 sites. Specific recognition of thymine residues in the ACS is carried out by a conserved basic amino acid motif of Orc1 in the minor groove, and by a species-specific helical insertion motif of Orc4 in the major groove. Moreover, similar insertions into major and minor grooves are also embedded in the B1 site by basic patch motifs from Orc2 and Orc5, respectively, to contact bases and to bend DNA. This work pinpoints a conserved role of ORC in modulating DNA structure to facilitate origin selection and helicase loading in eukaryotes.

Differences in aqueous humor protein profiles in patients with proliferative diabetic retinopathy before and after aflibercept treatment.

PURPOSE: To investigate the changes in aqueous humor (AH) protein profiles before and after intravitreal aflibercept (IVA) treatment in patients with proliferative diabetic retinopathy (PDR). METHODS: 5 PDR patients provided 10 samples of AH before and after IVA treatment (pre-group vs. post-group). Proteins were identified using liquid chromatography-tandem mass spectrometry. Then, bioinformatics was employed to investigate the functional significance of differentially expressed proteins (DEPs) and hub proteins. RESULTS: A total of 16 DEPs were identified, consisting of 8 downregulated proteins and 8 upregulated proteins. Bioinformatics analysis indicated that the most significantly enriched biological process was "blood coagulation, intrinsic pathway." The most significantly enriched signaling pathway was "complement and coagulation cascades." HBB, HPX, VEGFA, and CA1 were identified as hub proteins for IVA treatment. CONCLUSIONS: Together with the downregulation of the intravitreal vascular endothelial growth factor level, IVA may also change the AH protein composition in PDR patients, with DEPs involved in the blood coagulation, intrinsic pathway, complement, and coagulation cascades. IVA treatment may protect against PDR by regulating HBB, HPX, VEGFA, and CA1 expression.

Comparison of three-dimensional heads-up system versus traditional microscopic system in medical education for vitreoretinal surgeries: a prospective study.

BACKGROUND: To compare the value and efficiency of the three-dimensional (3D) heads-up surgical system and traditional microscopic (TM) system in teaching and learning vitreoretinal surgeries. METHODS: Twenty ophthalmologists and scrub nurses were recruited as teachers, and 45 junior ophthalmology residents and trainee doctors, trainee nurses, and medical students were recruited as observers. Each teacher and observer were assigned to both a 3D-assisted and TM-assisted vitreoretinal surgery and then asked to complete satisfaction questionnaires for both surgical systems at the end of each surgery. RESULTS: The 3D heads-up surgical system was rated significantly higher in most of the subscales and overall satisfaction score by both teachers and observers (P < 0.05). However, ratings for instrument adjustment were significantly higher in the TM group compared to the 3D group for junior ophthalmology residents and trainee doctors (6.1 ± 1.7 vs. 8.8 ± 1.1, P < 0.001). CONCLUSIONS: The 3D heads-up surgical system has great didactical value in the medical education of vitreoretinal surgeries, but it is important to consider the specific needs of different learners when choosing between the two systems. TRIAL REGISTRATION: Not applicable.