Sirolimus-eluting iron bioresorbable scaffold versus cobalt-chromium everolimus-eluting stents in patients with coronary artery disease: Rationale and design of the IRONMAN-II trial.

BACKGROUND: The previous first-in-human study established the preliminary safety and effectiveness of the novel thin-strut iron bioresorbable scaffold (IBS). The current study aims to directly compare the imaging and physiological efficacy, and clinical outcomes of IBS with contemporary metallic drug-eluting stents (DES). METHODS: A total of 518 patients were randomly allocated to treatment with IBS (257 patients) or metallic DES (261 patients) from 36 centers in China. The study is powered to test noninferiority of the IBS compared with the metallic everolimus-eluting stent in terms of the primary endpoint of in-segment late lumen loss at 2 years, and major secondary endpoints including 2-year quantitative flow ratio and cross-sectional mean flow area measured by optical coherence tomography (OCT) (limited to the OCT subgroup, 25 patients in each group). CONCLUSION: This will be the first powered randomized trial investigating the safety and efficacy of the novel thin-strut IBS compared to a contemporary metallic DES. The findings will provide valuable evidence for future research of this kind and the application of metallic bioresorbable scaffolds.

Protective effects of sinomenine against dextran sulfate sodium-induced ulcerative colitis in rats via alteration of HO-1/Nrf2 and inflammatory pathway.

BACKGROUND: Dextran Sulfate Sodium (DSS) induces ulcerative colitis (UC), a type of inflammatory bowel disease (IBD) that leads to inflammation, swelling, and ulcers in the large intestine. The aim of this experimental study is to examine how sinomenine, a plant-derived alkaloid, can prevent or reduce the damage caused by DSS in the colon and rectum of rats. MATERIAL AND METHODS: Induction of ulcerative colitis (UC) in rats was achieved by orally administering a 2% Dextran Sulfate Sodium (DSS) solution, while the rats concurrently received oral administrations of sinomenine and sulfasalazine. The food, water intake was estimated. The body weight, disease activity index (DAI), colon length and spleen index estimated. Antioxidant, cytokines, inflammatory parameters and mRNA expression were estimated. The composition of gut microbiota was analyzed at both the phylum and genus levels in the fecal samples obtained from all groups of rats. RESULTS: Sinomenine treatment enhanced the body weight, colon length and reduced the DAI, spleen index. Sinomenine treatment remarkably suppressed the level of NO, MPO, ICAM-1, and VCAM-1 along with alteration of antioxidant parameters such as SOD, CAT, GPx, GR and MDA. Sinomenine treatment also decreased the cytokines like TNF-α, IL-1, IL-1ß, IL-6, IL-10, IL-17, IL-18 in the serum and colon tissue; inflammatory parameters viz., PAF, COX-2, PGE2, iNOS, NF-κB; matrix metalloproteinases level such as MMP-1 and MMP-2. Sinomenine significantly (P < 0.001) enhanced the level of HO-1 and Nrf2. Sinomenine altered the mRNA expression of RIP1, RIP3, DRP3, NLRP3, IL-1ß, caspase-1 and IL-18. Sinomenine remarkably altered the relative abundance of gut microbiota like firmicutes, Bacteroidetes, F/B ratio, Verrucomicrobia, and Actinobacteria. CONCLUSION: The results clearly indicate that sinomenine demonstrated a protective effect against DSS-induced inflammation, potentially through the modulation of inflammatory pathways and gut microbiota.

Coupling Quantum Random Walks with Long- and Short-Term Memory for High Pixel Image Encryption Schemes.

This paper proposes an encryption scheme for high pixel density images. Based on the application of the quantum random walk algorithm, the long short-term memory (LSTM) can effectively solve the problem of low efficiency of the quantum random walk algorithm in generating large-scale pseudorandom matrices, and further improve the statistical properties of the pseudorandom matrices required for encryption. The LSTM is then divided into columns and fed into the LSTM in order for training. Due to the randomness of the input matrix, the LSTM cannot be trained effectively, so the output matrix is predicted to be highly random. The LSTM prediction matrix of the same size as the key matrix is generated based on the pixel density of the image to be encrypted, which can effectively complete the encryption of the image. In the statistical performance test, the proposed encryption scheme achieves an average information entropy of 7.9992, an average number of pixels changed rate (NPCR) of 99.6231%, an average uniform average change intensity (UACI) of 33.6029%, and an average correlation of 0.0032. Finally, various noise simulation tests are also conducted to verify its robustness in real-world applications where common noise and attack interference are encountered.

Spontaneous Resolution of Racemic Cage-Catenanes via Diastereomeric Enrichment at the Molecular Level and Subsequent Narcissistic Self-Sorting at the Supramolecular Level.

The spontaneous resolution of racemates, from natural compounds to artificial structures, has long been pursued to shed light on the origin of homochirality in life. Even though diverse synthetic systems have been elegantly devised to elaborate the underlying principles of spontaneous symmetry breaking, their complexity is still unparalleled to the natural masterpieces including DNA helix and proteins, which convey remarkable coalescence at both molecular and supramolecular levels. Here, we report on the spontaneous resolution of a pair of homochiral entities from a racemic mixture of a triply interlocked cage-catenane comprising 720 possible stereoisomers. This cage-catenane comprises six methyldithiane ring-containing linkers (denoted rac-2). As each methyldithiane ring has two chiral centers, it exhibits four possible diastereomers. These otherwise equimolar diastereomers are preferentially differentiated with the equatorial conformers over their axial analogues, leading to the dominant formation of (S, R)-2 and (R, S)-2, i.e., diastereomeric enrichment at the molecular level. This diastereomeric enrichment is unbiasedly transferred from precursor rac-2 to cage-catenane rac-4, from which a pair of homochirals (S, R)6-4 and (R, S)6-4 is narcissistically self-sorted upon crystallization. This powerful symmetry breaking is attributed to a supramolecular synergy of directional π-π stacking with the multivalency of erstwhile weak S···S contacts (with an unusual distance of 3.09 Å) that are cooperatively arranged in a helical fashion. This work highlights the attainability of complex homochiral entities by resorting to coalesced covalent and noncovalent contributions and therefore provides additional clues to the symmetry breaking of sophisticated yet well-defined architectures.

Association of symptom status, myocardial viability, and clinical/anatomic risk on long-term outcomes after chronic total occlusion percutaneous coronary intervention.

OBJECTIVES: This study aimed to examine the association of less-certain indication of chronic total occlusion percutaneous coronary intervention (CTO-PCI) with subsequent clinical outcomes. BACKGROUND: The impact of patient symptoms, myocardial viability, and clinical and anatomic risk on long-term outcomes is underdetermined. METHODS: Consecutive patients undergoing CTO-PCI at a large-volume single center between 2010 and 2013 were included. Central adjudication was used to assess the appropriateness of three prespecified indications. The primary outcome was the 5-year composite endpoint of death or myocardial infarction (MI). RESULTS: Of 2,659 patients with 2,735 CTO lesions, the 348 (13.1%) asymptomatic patients, 164 (6.2%) patients without viable myocardium in the CTO territory, and 306 (11.5%) patients in whom the Synergy between PCI with Taxus and Cardiac Surgery Score II favored coronary artery bypass grafting (CABG) had higher 5-year death or MI compared with the rest patients in each category (12.0% vs. 8.6%, p = .04; 16.3% vs. 8.5%, p < .0001; 12.2% vs. 8.6%, p = .03), respectively. Multivariable regression analysis demonstrated that without symptom (hazard ratio: 1.51; 95% confidence interval: 1.06-2.15; p = .02), non-viable myocardium in CTO territory (hazard ratio: 1.77; 95% confidence interval: 1.16-2.72; p = .009), and deemed more favorable for CABG (hazard ratio:1.54; 95% confidence interval: 1.04-2.28; p = .03), but not the technical success (hazard ratio:0.85; 95% confidence interval: 0.62-1.18; p = .34), were independent predictors for the primary endpoint. CONCLUSIONS: In this large cohort of CTO-PCI, those who were asymptomatic, non-viable myocardium in the CTO territory, or deemed more favorable for CABG were associated with higher risk of long-term mortality or MI.

Controlled Hierarchical Self-Assembly of Catenated Cages.

Constructing hierarchical superstructures to achieve comparable complexity and functions to proteins with four-level hierarchy is challenging, which relies on the elaboration of novel building blocks with complex structures. We present a series of catenated cages with unique structural complexity and tailorability. The rational design was realized as such: A catenane of two symmetric cages (CSC), CSC-1, with all rigid imine panels was converted to a catenane of two dissymmetric cages (CDC), CDC-1, with two exterior flexible amine panels, and CDC-5 was tailored from CDC-1 by introducing an additional methyl group on each blade to increase lateral hindrance. CDC-1s with the most irregular and flexible configuration formed supramolecular dimers, which self-organized into 3D continuous wavelike plank with a three-level hierarchy, previously undiscovered by conventional building blocks. A drastically different 3D triclinic crystalline phase with a four-level hierarchy and trigonal phase with a three-level hierarchy were constructed of distorted CSC-1s and the most symmetric CDC-5s, respectively. The wavelike plank exhibited the lowest order, and the triclinic phase had a lower order than the trigonal phase which had the highest order. It correlates with the configuration of the primary structures, namely, the most disordered shape of CDC-1, the low-order configuration of CSC-1, and the most ordered geometry of CDC-5. The catenated cages with subtle structural differences therefore provide a promising platform for the search of emerging hierarchical superstructures that might be applied to proton conductivity, ferroelectricity, and catalysis.

Quantitative flow ratio-guided strategy versus angiography-guided strategy for percutaneous coronary intervention: Rationale and design of the FAVOR III China trial.

BACKGROUND: Quantitative flow ratio (QFR) is a novel angiography-based approach enabling fast computation of fractional flow reserve without use of pressure wire or adenosine. The objective of this investigator-initiated, multicenter, patient- and clinical assessor-blinded randomized trial is to evaluate the efficacy and cost-effectiveness of a QFR-augmented angiography-guided (QFR-guided) strategy versus an angiography-only guided (angiography-guided) strategy for percutaneous coronary intervention (PCI) in patients with coronary artery disease. METHODS: Approximately 3,830 patients will be randomized in a 1:1 ratio to a QFR-guided or an angiography-guided strategy. Included subjects scheduled for coronary angiography have at least 1 lesion eligible for PCI with 50%-90% stenosis in an artery with ≥2.5 mm reference diameter. Subjects assigned to the QFR-guided strategy will have QFR measured in each interrogated vessel and undergo PCI when QFR ≤0.80, with deferral for lesions with QFR >0.80. Those assigned to the angiography-guided strategy will undergo PCI based on angiography. Optimal medical therapy will be administered to all treated and deferred patients. The primary end point is the 1-year rate of major adverse cardiac events (MACE), a composite of all-cause mortality, any myocardial infarction, or any ischemia-driven revascularization. The major secondary end point is 1-year MACE excluding periprocedural myocardial infarction. Other secondary end points include the individual components of MACE and cost-effectiveness end points. The sample size affords 85% power to demonstrate superiority of QFR guidance compared with angiography guidance. CONCLUSIONS: The FAVOR III China study will be the first randomized trial to examine the effectiveness and cost-effectiveness of a QFR-guided versus an angiography-guided PCI strategy in coronary artery disease patients.

First-in-man study of a thinner-strut sirolimus-eluting bioresorbable scaffold (FUTURE-I): Three-year clinical and imaging outcomes.

OBJECTIVES: The FUTURE-I study aimed to assess preliminary safety and effectiveness with the long-term clinical and imaging follow-up for the Firesorb (MicroPort, Shanghai, China), a thinner-strut sirolimus-eluting bioresorbable scaffold (BRS). BACKGROUND: First-generation BRS has been associated with unexpected device-related adverse outcomes at long-term follow-up. METHODS: In this prospective, open-label, first-in-man study, patients with single de novo lesions in native coronary arteries were randomized 2:1 into two cohorts after successful Firesorb implantation: cohort 1 (n = 30) underwent multimodality imaging assessment at 6 and 24 months; and cohort 2 (n = 15) at 12 and 36 months. All patients underwent clinical follow-up at 1, 6, and 12 months and annually up to 5 years. RESULTS: Between January and March 2016, 45 patients were enrolled. At 3-year follow-up, one patient had experienced target lesion failure and none scaffold thrombosis. In-scaffold minimal lumen diameter decreased significantly from 6-month to 2-year (2.53 ± 0.24 mm vs. 2.27 ± 0.37 mm, p = .0003), and only numerically from 1-year to 3-year follow-up (2.48 ± 0.28 mm vs. 2.22 ± 0.13 mm, p = .08). By optical coherence tomography, neointimal strut coverage at 3-year follow-up was 99.8%, and very low rate of late scaffold discontinuity was observed, only in one patient on two cross sections with three malapposed struts. CONCLUSIONS: At 3-year follow-up of the FUTURE-I study, implantation of the thinner-strut Firesorb BRS appeared preliminary feasible and effective in the treatment of patients with noncomplex coronary lesions.

Surgical removal of part of an occluder to treat iatrogenic coarctation of the aorta: a case report.

BACKGROUND: Iatrogenic aortic stenosis is a serious complication and potentially fatal due to erosion of the aortic wall. Timely management is necessary to prevent complications. CASE PRESENTATION: A 2-year-old boy underwent surgery to remove part of an Amplatzer occluder after patent ductus arteriosus (PDA) device embolization in the thoracic aorta. He exhibited moderate to severe obstruction with erosion of the intimal layer of the aorta caused by the device, part of which was retrieved surgically with restructuring of the thoracic aorta segment and occluder remnant. The patient's postoperative course was uneventful. CONCLUSIONS: When possible, retrieving only part of an embolized device can be advocated because it reduces the risk of aortic and pulmonary artery damage.

Localization Based on MAP and PSO for Drifting-Restricted Underwater Acoustic Sensor Networks.

Localization is a critical issue for Underwater Acoustic Sensor Networks (UASNs). Existing localization algorithms mainly focus on localizing unknown nodes (location-unaware) by measuring their distances to beacon nodes (location-aware), whereas ignoring additional challenges posed by harsh underwater environments. Especially, underwater nodes move constantly with ocean currents and measurement noises vary with distances. In this paper, we consider a special drifting-restricted UASN and propose a novel beacon-free algorithm, called MAP-PSO. It consists of two steps: MAP estimation and PSO localization. In MAP estimation, we analyze nodes' mobility patterns, which provide the priori knowledge for localization, and characterize distance measurements under the assumption of additive and multiplicative noises, which serve as the likelihood information for localization. Then the priori and likelihood information are fused to derive the localization objective function. In PSO localization, a swarm of particles are used to search the best location solution from local and global views simultaneously. Moreover, we eliminate the localization ambiguity using a novel reference selection mechanism and improve the convergence speed using a bound constraint mechanism. In the simulations, we evaluate the performance of the proposed algorithm under different settings and determine the optimal values for tunable parameters. The results show that our algorithm outperforms the benchmark method with high localization accuracy and low energy consumption.

STVF: Spatial-Temporal Variational Filtering for Localization in Underwater Acoustic Sensor Networks.

Localization is one of the critical services in Underwater Acoustic Sensor Networks (UASNs). Due to harsh underwater environments, the nodes often move with currents continuously. Consequently, the acoustic signals usually propagate with varying speeds in non-straight lines and the noise levels change frequently with the motion of the nodes. These limitations pose huge challenges for localization in UASNs. In this paper, we propose a novel localization method based on a variational filtering technique, in which the spatial correlation and temporal dependency information are utilized to improve localization performance. In the method, a state evolution model is employed to characterize the mobility pattern of the nodes and capture the uncertainty of the location transition. Then, a measurement model is used to reflect the relation between the measurements and the locations considering the dynamics of the acoustic speed and range noise. After that, a variational filtering scheme is adopted to determine the nodes’ locations, which consists of two phases: variational prediction and update. In the former phase, the coarse estimation of each node’ location is computed based on its previous location; in the latter phase, the coarse location is optimized by incorporating the measurements from the reference nodes as precisely as possible. At last, an iterative localization scheme is applied, in which a node labels itself as a reference node if the confidence of its location estimation is higher than the predefined threshold. We conducted extensive simulations under different parameter settings, and the results indicate that the proposed method has better localization accuracy compared to a typical SLMP algorithm while maintaining relatively high localization coverage. Moreover, spatial⁻temporal variational filtering (STVF) is more robust to the change of the parameter settings compared to SLMP.

Cold Priming Induced Tolerance to Subsequent Low Temperature Stress is Enhanced by Melatonin Application during Recovery in Wheat.

Cold priming can alleviate the effects of subsequent cold stress on wheat plant growth. Melatonin plays a key role in cold stress response in plants. In this study, the effects of foliar melatonin application during recovery on the cold tolerance of cold primed wheat plants were investigated. It was found that both melatonin and cold priming increased the photosynthetic rate and stomatal conductance, enhanced the activities of antioxidant enzymes, and altered the related gene expressions in wheat under cold stress. Melatonin application is helpful for the photosynthetic carbon assimilation and membrane stability of the cold primed plants under cold stress. These results suggested that foliar melatonin application during recovery enhanced the cold priming induced tolerance to subsequent low temperature stress in wheat.

Comparison of two biodegradable-polymer-based sirolimus-eluting stents with varying elution and absorption kinetics in patients with acute myocardial infarction: A subgroup analysis of the PANDA III trial.

BACKGROUND: Implantation of early-generation metallic drug-eluting stents (DES) in patients with acute myocardial infarction (AMI) is associated with poor vessel wall healing. Use of biodegradable polymer (BP) DES might improve safety outcomes; however, the impact of varying drug elution and polymer absorption kinetics of BP-DES on clinical outcomes in the AMI population is unknown. METHODS: This subgroup analysis of the randomized PANDA III trial included 732 patients (366 in each group) presenting with recent (<1 month) AMI. Primary endpoint was 1-year target lesion failure (TLF), a composite of cardiac death, target vessel myocardial infarction (MI), or ischemia-driven target lesion revascularization. Secondary endpoints included a patient-oriented composite endpoint (PoCE) of all-cause death, all MI, or any revascularization; individual TLF and PoCE components; and definite/probable stent thrombosis (ST). RESULTS: There were no significant differences between-groups in baseline clinical, angiographic, or procedural characteristics other than the proportion of post-dilatation, which was performed more frequently with the BuMA stent (53.9% vs. 44.5%; P = 0.004). After 1 year, compared to Excel SES implantation in patients with AMI, BuMA was associated with similar incidences of TLF and PoCE (5.5% vs. 8.3%, P = 0.14; 8.8% vs. 9.9%, P = 0.61, respectively) but lower incidences of MI (2.5% vs. 6.1%, P = 0.02), target vessel MI (2.2% vs. 5.8%, P = 0.01), and definite/probable ST (0.3% vs. 2.2%, P = 0.04). CONCLUSIONS: BuMA SES, with faster drug elution rate and polymer absorption kinetics, might improve safety outcomes compared to Excel SES in the high-risk AMI population. © 2017 Wiley Periodicals, Inc.

An Indoor Positioning Method for Smartphones Using Landmarks and PDR.

Recently location based services (LBS) have become increasingly popular in indoor environments. Among these indoor positioning techniques providing LBS, a fusion approach combining WiFi-based and pedestrian dead reckoning (PDR) techniques is drawing more and more attention of researchers. Although this fusion method performs well in some cases, it still has some limitations, such as heavy computation and inconvenience for real-time use. In this work, we study map information of a given indoor environment, analyze variations of WiFi received signal strength (RSS), define several kinds of indoor landmarks, and then utilize these landmarks to correct accumulated errors derived from PDR. This fusion scheme, called Landmark-aided PDR (LaP), is proved to be light-weight and suitable for real-time implementation by running an Android application designed for the experiment. We compared LaP with other PDR-based fusion approaches. Experimental results show that the proposed scheme can achieve a significant improvement with an average accuracy of 2.17 m.

First-in-man study evaluating the safety and efficacy of a second generation biodegradable polymer sirolimus-eluting stent in the treatment of patients with de novo coronary lesions: clinical, Angiographic, and OCT outcomes of CREDIT-1.

OBJECTIVE: To evaluate the preliminary safety and efficacy of the EXCEL II stent system. BACKGROUND: Although the first biodegradable polymer drug-eluting stent (BP-DES), EXCEL, was launched nearly a decade ago, in-stent restenosis and stent thrombosis remain pertinent clinical problems in practice. A new cobalt-chromium BP-DES EXCEL II has been developed with the aim of improving stent safety and efficacy. METHODS: Forty-five patients with single de novo native coronary lesions were enrolled and randomized to two groups in a 2:1 ratio, the 4-month follow-up group (n = 30) and the 12-month follow-up group (n = 15). All patients underwent percutaneous coronary intervention (PCI) with the EXCEL II stent system. Quantitative coronary angiography (QCA) and optical coherence tomography (OCT) were used to assess coronary vasculature at the designated 4- or 12-month follow-up. The primary outcome was major adverse cardiac events (MACE) at 30 days post-PCI. RESULTS: No MACE, thrombotic events, or target lesion failure was found in the 45 patients during the 12-month follow-up. There was no significant difference (P > 0.05) between the two groups in terms of in-stent and in-segment late lumen loss (LLL). No in-stent and in-segment restenosis was found in either group. At follow-up, the ratio of >10% uncovered struts per lesion was 26.67% in the 4-month group and 0% in the 12-month group (P < 0.05). Neointimal coverage in the 12-month group was significantly better than in the 4-month group (98.58% vs. 93.51%, P < 0.01). CONCLUSIONS: This first-in-man study demonstrates promising feasibility, safety, and efficacy of EXCEL II stents. These stents were found to have rapid endothelialization and low LLL rates at 4 and 12 months after implantation.

Transradial versus transfemoral method of two-stent implantation for true bifurcation lesions: comparison of immediate and long-term outcomes.

BACKGROUND: The feasibility, safety, and efficacy of two-stent implantation for true bifurcation disease through transradial (TR) versus transfemoral (TF) approaches have not been thoroughly investigated. METHODS AND RESULTS: We compared procedural and long-term outcomes of a two-stent strategy percutaneous revascularization in 805 consecutive patients with true bifurcation lesions requiring two-stent implantation via either a TR (n = 508) or TF (n = 297) approach from 2004 to 2009. Clinical and angiographic characteristics, procedural outcomes, and in-hospital and long-term clinical events were compared according to vascular access strategy. Using logistic regression to derive a propensity score model, 249 matched patient pairs were compared. The demographic, angiographic, and procedural characteristics were similar between groups, with the exception of less prior percutaneous intervention and left main bifurcation or multivessel disease in the TR group (all P < 0.05). Angiographic success and fluoroscopy time were similar between cohorts. The duration of hospitalization and in-hospital occurrence of Bleeding Academic Research Consortium defined bleeding (3.9% vs. 9.1%, P < 0.01) were significantly lower in the TR group. During a mean follow-up period of 55 ± 22 months, in a multivariate regression analysis, the TR method was not predictive of major adverse cardiac events (adjusted hazards ratio [HR]: 1.33, 95% confidence interval [CI]: 0.83-2.14), cardiac death, myocardial infarction, target vessel revascularization (HR: 0.93, 95% CI: 0.45-1.93), or stent thrombosis. CONCLUSION: In comparison to TF vascular access, two-stent implantation via TR approach for true bifurcation lesions is associated with similar in-hospital outcomes, shorter hospitalization, reduced bleeding, and comparable long-term clinical safety and efficacy.

Biomechanics of annulus fibrosus: Elastic fiber simplification and degenerative impact on damage initiation and propagation.

This study addresses three primary objectives related to lumbar intervertebral disc (IVD) biomechanics under ramping quasi-static loading conditions. First, we explore the conditions justifying the simplification of axisymmetric elastic fiber families into single fiber bundles through discretized strain energy functions. Simulations reveal that a concentration factor exceeding 10 allows for a consistent deviation below 10% between simplified and non-simplified responses. Second, we investigate the impact of elastic fibers on the physiological stiffness in IVDs, revealing minimal influence on biological motions but significant effects on degeneration. Lastly, we examine the initiation and progression of annulus fibrosus (AF) damage. Our findings confirm the validity of simplifying elastic fiber families and underscore the necessity of considering elastic fiber damage in biomechanical studies of AF tissues. Elastic fibers contribute to increased biaxial stretch stiffness, and their damage significantly affects the loading capacity of the inner AF. Additionally, degeneration significantly alters the susceptibility to damage in the AF, with specific regions exhibiting higher vulnerability. Damage tends to extend circumferentially and radially, emphasizing the regional variations in collagen and elastic fiber properties. This study offers useful insights for refining biomechanical models, paving the way for a more comprehensive understanding of IVD responses and potential clinical implications.

Comprehensive modeling of annulus fibrosus: From biphasic refined characterization to damage accumulation under viscous loading.

The annulus fibrosus (AF), a permeable, hydrated, and fiber-reinforced soft tissue, exhibits complex responses influenced by fluid pressure, osmotic pressure, and structural mechanics. Existing models struggle to comprehensively represent these intricate interactions and the heterogeneous solid responses within the AF. Additionally, the mechanisms driving differential damage accumulation between non-degenerative and degenerative intervertebral discs remain poorly understood. In this study, we introduce a biphasic-swelling damage model for the AF. We conceptually develop and rigorously validate this model through tissue-level tests employing various loading modes, consistently aligning model predictions with experimental data. Leveraging parametric geometric algorithms and custom Python scripts, we construct models simulating both non-degenerative and degenerative discs. Following calibration, we subject these models to viscous loading protocols. Our findings reveal the posterior AF's susceptibility to damage, contingent upon loading rate and water content. We elucidate the underlying mechanisms by examining the temporal evolution of fluid pressure, osmotic pressure, and the regionally dependent fiber network. This research presents a highly accurate model of the AF, providing valuable insights into disc damage. Future research endeavors should expand this model to incorporate ionic transport and diffusion, enabling a more profound exploration of intervertebral disc mechanobiology. This comprehensive model contributes to a better understanding of AF behavior and may inform therapeutic strategies for disc-related pathologies. STATEMENT OF SIGNIFICANCE: This research presents a comprehensive model of the annulus fibrosus (AF), a crucial component of the intervertebral disc that provides structural support and resists deformation. The study introduces a biphasic-swelling damage model for the AF and validates it through tissue-level tests. The model accounts for fluid pressure, osmotic pressure, and matrix mechanics, providing a more accurate representation of the AF's behavior. The study also investigates the differential damage accumulation between non-degenerative and degenerative discs, shedding light on the mechanisms driving disc degeneration. The findings have significant implications for medical treatments and interventions, as they highlight the posterior AF's susceptibility to damage. This research is of great interest to readers interested in biomechanics, tissue engineering, and medical treatments for disc degeneration.

Multi-parameter design of triply periodic minimal surface scaffolds: from geometry optimization to biomechanical simulation.

This study introduces a multi-parameter design methodology to create triply periodic minimal surface (TPMS) scaffolds with predefined geometric characteristics. The level-set constant and unit cell lengths are systematically correlated with targeted porosity and minimum pore sizes. Network and sheet scaffolds featuring diamond, gyroid, and primitive level-set structures are generated. Three radially graded schemes are applied to each of the six scaffold type, accommodating radial variations in porosity and pore sizes. Computer simulations are conducted to assess the biomechanical performance of 18 scaffold models. Results disclose that diamond and gyroid scaffolds exhibit more expansive design ranges than primitive counterparts. While primitive scaffolds display the highest Young's modulus and permeability, their lower yield strength and mesenchymal stem cell (MSC) adhesion render them unsuitable for bone scaffolds. Gyroid scaffolds demonstrate superior mechanical and permeability performances, albeit with slightly lower MSC adhesion than diamond scaffolds. Sheet scaffolds, characterized by more uniform material distribution, exhibit superior mechanical performance in various directions, despite slightly lower permeability. The higher specific surface area of sheet scaffolds contributes to elevated MSC adhesion. The stimulus factor analysis also revealed the superior differentiation potential of sheet scaffolds over network ones. The diamond sheet type demonstrated the optimal differentiation. Introducing radial gradations enhances axial mechanical performance at the expense of radial mechanical performance. Radially decreasing porosity displays the highest permeability, MSC adhesion, and differentiation capability, aligning with the structural characteristics of human bones. This study underscores the crucial need to balance diverse biomechanical properties of TPMS scaffolds for bone tissue engineering.

Comparing the osteogenesis outcomes of different lumbar interbody fusions (A/O/X/T/PLIF) by evaluating their mechano-driven fusion processes.

BACKGROUND: In lumbar interbody fusion (LIF), achieving proper fusion status requires osteogenesis to occur in the disc space. Current LIF techniques, including anterior, oblique, lateral, transforaminal, and posterior LIF (A/O/X/T/PLIF), may result in varying osteogenesis outcomes due to differences in biomechanical characteristics. METHODS: A mechano-regulation algorithm was developed to predict the fusion processes of A/O/X/T/PLIF based on finite element modeling and iterative evaluations of the mechanobiological activities of mesenchymal stem cells (MSCs) and their differentiated cells (osteoblasts, chondrocytes, and fibroblasts). Fusion occurred in the grafting region, and each differentiated cell type generated the corresponding tissue proportional to its concentration. The corresponding osteogenesis volume was calculated by multiplying the osteoblast concentration by the grafting volume. RESULTS: TLIF and ALIF achieved markedly greater osteogenesis volumes than did PLIF and O/XLIF (5.46, 5.12, 4.26, and 3.15 cm3, respectively). Grafting volume and cage size were the main factors influencing the osteogenesis outcome in patients treated with LIF. A large grafting volume allowed more osteoblasts (bone tissues) to be accommodated in the disc space. A small cage size reduced the cage/endplate ratio and therefore decreased the stiffness of the LIF. This led to a larger osteogenesis region to promote osteoblastic differentiation of MSCs and osteoblast proliferation (bone regeneration), which subsequently increased the bone fraction in the grafting space. CONCLUSION: TLIF and ALIF produced more favorable biomechanical environments for osteogenesis than did PLIF and O/XLIF. A small cage and a large grafting volume improve osteogenesis by facilitating osteogenesis-related cell activities driven by mechanical forces.