Characterization of Limbus Biomechanical Properties Using Optical Coherence Elastography.

The elasticity of the limbus is crucial for ocular health, yet it remains inadequately explored. This study employs acoustic radiation force optical coherence elastography (ARF-OCE) to evaluate the biomechanical properties of the limbus under varying intraocular pressures. The method was validated using a heterogeneous phantom and subsequently applied to ex vivo porcine limbus samples. Elastic wave velocity at specific locations within the limbus was calculated, and the corresponding Young's modulus values were obtained. Spatial elasticity distribution maps were generated by correlating Young's modulus values with their respective locations in the two-dimensional structural images. The results indicate that ARF-OCE enhances the understanding of limbus biomechanical behavior and holds potential for diagnosing regional variations caused by ocular diseases.

Corneal biomechanical properties and potential influencing factors in varying degrees of myopia.

To compare the corneal biomechanical parameters measured by Corvis ST in subjects with varying degrees of myopia. And the factors that may affect corneal biomechanical properties were also investigated. Participants in this prospective cross-sectional study were classified into three groups according to spherical equivalent (SE) and axial length (AL): Non-myopia (NM, SE > - 0.50 D and AL < 26 mm), Mild-to-moderate myopia (MM, - 6.00 D < SE ≤ - 0.50 D and AL < 26 mm), high myopia (HM, SE ≤ - 6.00 D or AL ≥ 26 mm). Ten corneal biomechanical parameters were finally included. Linear mixed-effects model accounting for using both eyes in the same participant was carried out to evaluate how the corneal biomechanical parameter was influenced by varying degrees of myopia after adjusting for biomechanically corrected intraocular pressure (bIOP) and central corneal thickness (CCT). Further, multiple linear regression was performed to explore the correlation between corneal biomechanical parameter and SE, AL, bIOP or CCT. A total of 304 eyes from 224 healthy myopic subjects were recorded. There were 95 eyes with NM, 122 eyes with MM, and 87 eyes with HM. After adjusting for bIOP and CCT, eyes with high myopia showed shorter highest concavity time (HC-time, p = 0.025), greater peak distance (PD, p = 0.001), greater deflection amplitude (DA-Max, p = 0.002), smaller whole eye movement (WEM-Max, p < 0.001) and reduced stiffness parameter (SP-A1, p < 0.001). Multiple regression analysis showed that five parameters (HC-time, p < 0.001; PD, p < 0.001; DA-Max, p = 0.001; WEM-Max, p < 0.001; and SP-A1, p < 0.001) of Corvis ST were significantly correlated with AL, and one parameter (Corvis biomechanical index, p = 0.016) has significant relationship with SE. With the increase of myopia, significant changes in several corneal biomechanical parameters indicated a progressive decrease in corneal stiffness, independent of bIOP and CCT. Corneal biomechanical parameters may be predictors of scleral mechanical strength in high myopia, which has certain application value in clinical management of myopia.

Assessment of differences in mechanical properties and thickness of temporal and occipital bones and correlation with age in Japanese forensic samples.

The mechanical properties and thickness of adult temporal and occipital bones were examined in modern Japanese forensic samples. Cranial bones were obtained from 293 Japanese corpses (179 men and 114 women). During autopsy, left temporal (LT), right temporal (RT), and occipital (O) bone samples were extracted from each skull. Sample thickness (ST) was measured using multidetector computed tomographic imaging. The fracture load (FL) of each sample was measured by a bending test, in which the flexural strength (FS) was calculated. The FL and ST values for O were significantly greater compared with those of the LT and RT bones. The temporal bones were thinner compared with other parts of the skull and at greater risk for fracture. There is a need to take precautions to prevent temporal bone fractures. There were no significant differences in any of the values between LT and RT, indicating bilateral symmetry of the temporal bones. There were significant negative correlations between age and the FL and FS values for all sites in both sexes, except for O in the male samples, suggesting that older individuals are at increased risk for fractures. No significant correlations were observed between age and ST values in any of the samples. There were significantly positive correlations between FL and ST values at all sites regardless of sex.

A narrative review of the measurement methods for biomechanical properties of plantar soft tissue in patients with diabetic foot.

This article provides an overview of the development history and advantages and disadvantages of measurement methods for soft tissue properties of the plantar foot. The measurement of soft tissue properties is essential for understanding the biomechanical characteristics and function of the foot, as well as for designing and evaluating orthotic devices and footwear. Various methods have been developed to measure the properties of plantar soft tissues, including ultrasound imaging, indentation testing, magnetic resonance elastography, and shear wave elastography. Each method has its own strengths and limitations, and choosing the most appropriate method depends on the specific research or clinical objectives. This review aims to assist researchers and clinicians in selecting the most suitable measurement method for their specific needs.

From Biomechanical Properties to Morphological Variations: Exploring the Interplay between Aortic Valve Cuspidity and Ascending Aortic Aneurysm.

Background: This research explores the biomechanical and structural characteristics of ascending thoracic aortic aneurysms (ATAAs), focusing on the differences between bicuspid aortic valve aneurysms (BAV-As) and tricuspid aortic valve aneurysms (TAV-As) with non-dilated aortas to identify specific traits of ATAAs. Methods: Clinical characteristics, laboratory indices, and imaging data from 26 adult patients operated on for aneurysms (BAV-A: n = 12; TAV-A: n = 14) and 13 controls were analyzed. Biomechanical parameters (maximal aortic diameter, strain, and stress) and structural analyses (collagen fiber organization, density, fragmentation, adipocyte deposits, and immune cell infiltration) were assessed. Results: Significant differences in biomechanical parameters were observed. Median maximal strain was 40.0% (control), 63.4% (BAV-A), and 45.3% (TAV-A); median maximal stress was 0.59 MPa (control), 0.78 MPa (BAV-A), and 0.48 MPa (TAV-A). BAV-A showed higher tangential modulus and smaller diameter, with substantial collagen fragmentation (p < 0.001 vs. TAV and controls). TAV-A exhibited increased collagen density (p = 0.025), thickening between media and adventitia layers, and disorganized fibers (p = 0.036). BAV-A patients had elevated adipocyte deposits and immune cell infiltration. Conclusions: This study highlights distinct pathological profiles associated with different valve anatomies. BAV-A is characterized by smaller diameters, higher biomechanical stress, and significant collagen deterioration, underscoring the necessity for tailored clinical strategies for effective management of thoracic aortic aneurysm.

Biomechanical changes of the cornea after orbital decompression in thyroid-associated orbitopathy measured by corvis ST.

This study aims to investigate the changes in ocular biomechanical factors in patients with inactive thyroid eye disease (TED) who undergo orbital decompression surgery. This observational prospective study include 46 eyes of 31 patients with inactive TED undergoing orbital decompression at a tertiary university hospital from October 2021 to September 2023. All participants underwent a full ophthalmic examination, and a biomechanical examination was performed using corvis ST at baseline, 1 month, and 3 months postoperatively. The study participants had a mean age of 45 ± 11.6 years, and 58.1% of them were female. The second applanation time (A2T) increased from baseline to postoperative month 1 and continued to increase to postoperative month 3 (P < 0.001). The first applanation velocity (A1V), highest concavity (HC) peak distance, and pachymetry parameters also increased from postoperative month 1 to postoperative month 3 (P = 0.035, P = 0.005, and P = 0.031, respectively). The HC time increased from baseline to postoperative month 3 (P = 0.027). Other changes were statistically insignificant. The P-values were adjusted according to biomechanically corrected intraocular pressure (bIOP). Baseline Hertel significantly influenced A2 time (P < 0.001). Our findings suggest that ocular biomechanical parameters may change following decompression surgery in patients with inactive TED. Specifically, an increase in A2T, A1V, and HC peak distance suggests a decrease in corneal stiffness, although the increased HC time contradicts this. It is recommended to postpone keratorefractive or intraocular lens implantation surgeries until corneal biomechanics stabilize after decompression surgery for optimal results.

Biomechanical properties of the capsule and extracellular matrix play a major role during the Wolffian/epididymal duct development.

BACKGROUND: The epididymis is important for sperm maturation and without its proper development, male infertility will result. Biomechanical properties of tissues/organs play key roles during their morphogenesis, including the Wolffian duct. It is hypothesized that structural/bulk stiffness of the capsule and mesenchyme/extracellular matrix that surround the duct is a major biomechanical property that regulates Wolffian duct morphogenesis. These data will provide key information as to the mechanisms that regulate the development of this important organ. OBJECTIVES: To measure the structural/bulk stiffness in Pascals (force/area) of the capsule and the capsule and mesenchyme together that surrounds the Wolffian duct during the development. To examine the relative membrane tension of mesenchymal cells during the Wolffian duct development. Since Ptk7 was previously shown to regulate ECM integrity and Wolffian duct elongation and coiling, the hypothesis that Ptk7 regulates structural/bulk stiffness and mesenchymal cell membrane tension was tested. MATERIALS AND METHODS: Atomic force microscopy and a microsquisher compression apparatus were used to measure the structural stiffness. Biomechanical properties within the membranes of cells within the capsule and mesenchyme were examined using a membrane-tension fluorescent probe. RESULTS AND DISCUSSION: The structural stiffness (Pascals) of the capsule and underlying mesenchyme was relatively constant during development, with a significant increase in the capsule at the later stages. However, this increase may reflect the ECM and associated mesenchyme being close to the capsule because the coiling of the duct pushed or compressed them into that space. Keeping the capsule and mesenchyme/ECM at constant stiffness would ensure that the duct will continue to coil under similar biomechanical forces throughout the development. Cells within the capsule and mesenchyme at different Wolffian duct regions during the development had varying degrees of membrane lipid tension. It is hypothesized that the dynamic changes ensure the duct is kept at a constant stiffness regardless of any external forces. Loss of Ptk7 resulted in an increase in stiffness at E18.5, which was presumable due to the loss of integrity of the ECM within the mesenchyme. CONCLUSION: Biomechanical properties of the capsule and the mesenchyme/extracellular matrix that surround the Wolffian duct play an important role toward Wolffian duct morphogenesis, thereby allowing for the proper development of the epididymis and subsequent male fertility.

Numerical evaluation of spinal reconstruction using a 3D printed vertebral body replacement implant: effects of material anisotropy.

Background and objective: Artificial vertebral implants have been widely used for functional reconstruction of vertebral defects caused by tumors or trauma. However, the evaluation of their biomechanical properties often neglects the influence of material anisotropy derived from the host bone and implant's microstructures. Hence, this study aims to investigate the effect of material anisotropy on the safety and stability of vertebral reconstruction. Material and methods: Two finite element models were developed to reflect the difference of material properties between linear elastic isotropy and nonlinear anisotropy. Their biomechanical evaluation was carried out under different load conditions including flexion, extension, lateral bending and axial rotation. These performances of two models with respect to safety and stability were analyzed and compared quantitatively based on the predicted von Mises stress, displacement and effective strain. Results: The maximum von Mises stress of each component in both models was lower than the yield strength of respective material, while the predicted results of nonlinear anisotropic model were generally below to those of the linear elastic isotropic model. Furthermore, the maximum von Mises stress of natural vertebra and reconstructed system was decreased by 2-37 MPa and 20-61 MPa, respectively. The maximum reductions for the translation displacement of the artificial vertebral body implant and motion range of whole model were reached to 0.26 mm and 0.77°. The percentage of effective strain elements on the superior and inferior endplates adjacent to implant was diminished by up to 19.7% and 23.1%, respectively. Conclusion: After comprehensive comparison, these results indicated that the finite element model with the assumption of linear elastic isotropy may underestimate the safety of the reconstruction system, while misdiagnose higher stability by overestimating the range of motion and bone growth capability.

Effects of wearable low-intensity continuous ultrasound on muscle biomechanical properties during delayed onset muscle soreness.

BACKGROUND: Delayed onset muscle soreness (DOMS) is one of the most prevalent musculoskeletal symptoms in individuals engaged in strenuous exercise programs. OBJECTIVE: This study investigated the effects of wearable low-intensity continuous ultrasound on muscle biomechanical properties during DOMS. METHODS: Twenty volunteers were distributed into a wearable ultrasound stimulation group (WUG) (n= 10) and medical ultrasound stimulation group (MUG) (n= 10). All subjects performed wrist extensor muscle strength exercises to induce DOMS. At the site of pain, ultrasound of frequency 3 MHz was applied for 1 h or 5 min in each subject of the WUG or MUG, respectively. Before and after ultrasound stimulation, muscle biomechanical properties (tone, stiffness, elasticity, stress relaxation time, and creep) and body temperature were measured, and pain was evaluated. RESULTS: A significant decrease was found in the tone, stiffness, stress relaxation time, and creep in both groups after ultrasound stimulation (all p< 0.05). A significant decrease in the pain and increases in temperature were observed in both groups (all p< 0.05). No significant differences were observed between the groups in most evaluations. CONCLUSION: The stiffness and pain caused by DOMS were alleviated using a wearable ultrasound stimulator. Furthermore, the effects of the wearable ultrasound stimulator were like those of a medical ultrasound stimulator.

Effect of repeated steam sterilizations on insertional torque, torque to failure, and axial pullout strength of 3.5-mm and 2.0-mm cortical bone screws.

OBJECTIVE: The objective of this study was to determine the effects of repeated steam sterilization cycles on the biomechanical properties of surgical screws. METHODS: 42 3.5-mm and 42 2.0-mm self-tapping, cortical screws were divided into 3 groups per size and underwent autoclave sterilization for 1 (G1), 50 (G50), or 100 (G100) cycles and testing from August 2018 through June 2021. Sixty screws were then inserted into canine cadaver femurs, and biomechanical properties were measured, including peak insertional torque, torque to failure, and pullout strength, each normalized to cortical thickness. Scanning electron micrographs were taken from 24 screws, and images were blindly analyzed by 5 trained examiners. RESULTS: The mean normalized insertion torque for 3.5-mm screws was significantly different between G1 and both G50 and G100. The mean normalized torque to failure for 3.5-mm screws was significantly different between G1 and both G50 and G100. Axial pullout testing was found to be significantly different for 2.0-mm screws between G1 and G100. Scanning electron micrographs surface scoring identified a significant difference in 3.5-mm screws at the screw tip. CONCLUSIONS: The results indicate that biomechanical changes occur with repeated steam sterilizations. Specifically, peak insertional torque and torque to failure are decreased with increased sterilizations for 3.5-mm screws, whereas 2.0-mm screws were altered in pullout testing after 100 sterilizations. It is suspected that numerous sterilizations negatively alter the physical-mechanical properties of certain screw sizes. CLINICAL RELEVANCE: The biomechanical properties of the bone-implant interface could negatively be affected by multiple steam sterilizations during clinical setting.

Bleeding simulation with stepless adaptive particles for surgical simulation systems.

BACKGROUND AND OBJECTIVES: In virtual surgery, the resolution of bleeding surface has a significant impact on the realism. The computational complexity of internal particles reduces real-time performance, which has no obvious contribution to the visual effect of simulation. This paper focuses on the study of bleeding simulation in virtual surgery to improve the visual realism while meeting real-time performance and physical properties. An innovative adaptive-particle-based algorithm is proposed, which combines the repulsive force and the biomechanical properties, to achieve both realistic and computational efficiency in bleeding simulation. METHODS: This paper integrates three modules based on Lagrangian particle method to achieve high fidelity real-time bleeding simulation in virtual surgery. Stepless adaptive particle algorithm is proposed to change the mass (radius) based on the proportion of particle positions between the bleeding surface and the soft tissue, which improves the resolution of bleeding surface and reduces the computational complexity of internal particles. The particle repulsion is introduced to avoid volume distortion caused by permeation of adaptive particles during collision, meeting the requirement of mass conservation. The biomechanics of bleeding particles are explored through the improved smoothed particle hydrodynamics (SPH) algorithm solving the Navier-Stokes (N-S) equation to improve the realism of physical properties. RESULTS AND CONCLUSIONS: Compared to traditional simulation, the method proposed in this paper performs smoother bleeding surface, especially when topological changes occur during suction operation. Through particle tracking curves, it is possible to visually read the stepless variations of particle radius with position in different regions. Bleeding simulation is suitable for the bleeding effect of various types of wounds, which is well applied in virtual surgical scenes.

Brillouin spectroscopy of medically relevant samples of bovine jugular vein and pericardium.

There is the rapid growth in application of Brillouin scattering spectroscopy to biomedical objects in order to characterize their mechanoelastic properties in this way. However, the possibilities and limitations of the method when applied to tissues have not yet been clarified. Here, applicability of Brillouin spectroscopy for testing the elastic response of medically relevant tissues of bovine jugular vein and pericardium was considered. Parameters of the Brillouin peak were studied for samples untreated, diepoxide-fixed, and preserved after treatment in alcohol solutions. It was found that diepoxide cross-linking resulted to a slight tendency to increase the Brillouin position for hydrated tissues. The variations in the position and width of the Brillouin peaks, associated with local fluctuations in water concentration, were reduced after diepoxide treatment in the case of the pericardium, but not in the case of the vein wall. To obtain more information about the elastic response of the protein scaffold without the participation of water, dried samples were also studied. Brillouin spectra of the dried pericardium and vein wall revealed a significant increase in the Brillouin peak position (elastic modulus) after conservation in alcohol. In the case of the vein wall, this effect was found for both collagen and elastin-related peaks, which were identified in the Brillouin spectrum. This result corresponds to a denser packing of fibrous proteins after preservation in alcohol solutions. The ability of Brillouin spectroscopy to independently characterize the effect of treatment on the instantaneous elastic modulus of various tissue components is also attractive for its application in the development of new materials for bioimplants. A comparison of the Brillouin longitudinal and Young's elastic moduli determined for the hydrated samples of the vein and pericardium showed that there is no clear correspondence between these material parameters. The usefulness of using both experimental methods to obtain new information about the elastic response of the material is discussed.

Detecting emergence of ruptures in individual layers of the stretched intestinal wall using optical coherence elastography: A pilot study.

We report a new application of compression optical coherence elastography (C-OCE) to monitor the emergence of ruptures in individual layers of longitudinally stretched small-intestine walls using tissue samples (n = 36) from nine minipigs. Before stretching, C-OCE successfully estimated stiffness for each intestine-wall layer: longitudinal muscular layer with serosa, circumferential muscular layer, submucosa and mucosa. In stretched samples, C-OCE clearly visualized initial stiffening in both muscular layers. By 25% elongation, a sharp stiffness decrease for the longitudinal muscular layer, indicated emergence of tears in all samples. With further stretching, for most samples, ruptures emerged in the circumferential muscular layer and submucosa, while mucosa remained undamaged. Histology confirmed the OCE-revealed damaging and absence of tissue damage for ~15% elongation. Thus, C-OCE has demonstrated a high potential for determining the safety tissue-stretching threshold which afterward may be used intraoperatively to prevent rupture risk in intestinal tissues stretched during various diagnostic/therapeutic procedures.

Biomimetic and Nonbiomimetic Approaches in Dura Substitutes: The Influence of Mechanical Properties.

The dura mater, the furthest and strongest layer of the meninges, is crucial for protecting the brain and spinal cord. Its biomechanical behavior is vital, as any alterations can compromise biological functions. In recent decades, interest in the dura mater has increased due to the need for hermetic closure of dural defects prompting the development of several substitutes. Collagen-based dural substitutes are common commercial options, but they lack the complex biological and structural elements of the native dura mater, impacting regeneration and potentially causing complications like wound/postoperative infection and cerebrospinal fluid (CSF) leakage. To face this issue, recent tissue engineering approaches focus on creating biomimetic dura mater substitutes. The objective of this review is to discuss whether mimicking the mechanical properties of native tissue or ensuring high biocompatibility and bioactivity is more critical in developing effective dural substitutes, or if both aspects should be systematically linked. After a brief description of the properties and architecture of the native cranial dura, we describe the advantages and limitations of biomimetic dura mater substitutes to better understand their relevance. In particular, we consider biomechanical properties' impact on dura repair's effectiveness. Finally, the obstacles and perspectives for developing the ideal dural substitute are explored.

Femoral bone structure and mechanics at the edge and core of an expanding population of the invasive frog Xenopus laevis.

Understanding how living tissues respond to changes in their mechanical environment is a key question in evolutionary biology. Invasive species provide an ideal model for this as they are often transplanted between environments that differ drastically in their ecological and environmental context. Spatial sorting, the name given to the phenomenon driving differences between individuals at the core and edge of an expanding range, has been demonstrated to impact the morphology and physiology of Xenopus laevis from the invasive French population. Here, we combined a structural analysis using micro-CT scanning and a functional analysis by testing the mechanical properties of the femur to test whether the increased dispersal at the range edge drives differences in bone morphology and function. Our results show significant differences in the inner structure of the femur as well as bone material properties, with frogs from the centre of the range having more robust and resistant bones. This is suggestive of an energy allocation trade-off between locomotion and investment in bone formation, or alternatively, may point to selection for fast locomotion at the range edge. Overall, our results provide insights on the growth of the long bones and the formation of trabecular bone in frogs.

Biomechanical evaluation of fixation of the coracoclavicular stand-alone cow-hitch suture reconstruction in comparison to two established techniques for highly unstable distal clavicle fractures (Neer type V).

Background: Treatment of displaced distal clavicle fractures with bony avulsion of the coracoclavicular (CC) ligaments often warrants surgical fixation, yet a gold standard surgical technique is to be defined. The purpose of this study was to compare the biomechanical fixation strength of a new fixation technique, the CC stand-alone cow-hitch suture reconstruction, and to compare this technique with a clavicle hook plate and a lateral locking plate with CC suture reconstruction. Methods: Simulated Neer type V distal clavicle fractures of the clavicle were created in 18 cadaveric shoulders, which were matched by age and gender in 3 groups: (1) clavicle hook plate (group HP), (2) lateral locking plate fixation with CC suture reconstruction (group LPCC), and (3) CC stand-alone suture reconstruction using the cow-hitch technique (group CH). After preconditioning with 25 N for 10 cycles, the specimens were cycled in the coronal plane for 500 cycles from 10N to 70N. Displacement and ultimate load to failure were documented and analyzed with the data acquisition system. Results: There was a significant difference in the fracture displacement during cyclic loading between the LPCC group and the HP group (0.6 vs. 1.7 mm; P = .02) and between the CH and HP groups (0.5 vs. 1.7 mm; P = .004). Fracture displacement was not different between the LPCC and the CH groups (P = .544). The CH group and the LPCC group showed a significantly higher stiffness compared to the HP group (P < .001 and P = .003, respectively). The CH group showed a significantly higher ultimate load to failure compared with the HP group (429 vs. 172 N; P = .005) and showed a tendency toward higher ultimate load to failure when compared with the LPCC group (429 vs. 258 N; P = .071). Conclusion: The CC stand-alone cow-hitch suture reconstruction and the locking plate with CC reconstruction showed higher fixation strength compared with the hook plate for simulated Neer type V distal clavicle fractures. There was a tendency of higher ultimate load to failure with the cow-hitch technique compared with the lateral locking plate with CC suture reconstruction, and given the potential advantages of less soft tissue stripping, metal-free fixation, low costs, and simple surgical technique, clinical application of the all-suture CC reconstruction using the cow-hitch for Neer type V distal clavicle fractures appears warranted.

Acute alcohol consumption modulates corneal biomechanical properties as revealed by optical coherence elastography.

Acute alcohol ingestion has been found to impact visual functions, including eye movement, but its effects on corneal biomechanical properties remain unclear. This study aimed to investigate the influence of acute alcohol consumption on corneal biomechanical properties using optical coherence elastography (OCE). An air-coupled ultrasound transducer induced elastic waves in mice corneas in vivo, and a high-resolution phase-sensitive optical coherence tomography (OCT) system tracked the mechanical waves to quantify the elastic wave speed. In vivo measurements were performed on three groups of age- and gender-matched mice: control, placebo (administered saline), and alcohol (administered ethanol) groups. Longitudinal measurements were conducted over a one-hour period to assess acute temporal changes in wave speeds, which are associated with inherent biomechanical properties of the cornea. The results showed a significant decrease in wave speed for the alcohol group after 10 min of ingestion in comparison to pre-ingestion values (p = 0.0096), whereas the temporal wave speed changes for the placebo group were statistically insignificant (p = 0.076). In contrast, the control group showed no significant changes in elastic wave speed and corneal thickness. Furthermore, a significant difference was observed between the wave speeds of the placebo and alcohol groups at each measurement time point between 10 and 50 min (p < 0.05), though both groups exhibited a similar trend in corneal thickness change. The findings of this study have important implications for clinical assessments and research in corneal disorders, highlighting the potential of OCE as a valuable tool for evaluating such changes.

A randomized intraindividual comparative study evaluating the effects of two ultrasound-assisted liposuction devices on the abdomen.

BACKGROUND: Ultrasound-assisted liposuction (UAL) has become popular because of its favorable outcomes in fat emulsification, blood loss reduction, and skin tightening. This study aimed to compare the effects of two UAL devices on the abdomen by assessing postsurgery skin biomechanical properties. METHODS: This single-blind, prospective study (2020-2022) involved 13 liposuction procedures performed on patients without chronic diseases. Each patient's abdomen was divided vertically from the xiphoid to the perineum. Vibration amplification of sound energy at resonance (VASER)-assisted liposuction (Solta Medical, Inc., Hayward, CA) was performed on one half, while the other half underwent liposuction with high-frequency ultrasound energy (HEUS)-assisted technology. Skin biomechanical measurements, including distensibility, net elasticity, biological elasticity, hydration, erythema, melanin, and skin firmness, were taken at 12 and 24 months postsurgery, focusing on the anterior abdomen, 8 cm to the right and left of the umbilicus. RESULTS: Analysis of the above skin biomechanical measurements revealed no significant differences between the HEUS and VASER devices, except for skin firmness, which showed a notable increase following HEUS surgery. Patient-perceived clinical differences were assessed via nonvalidated questionnaires, revealing no distinctions between devices. CONCLUSION: Biomechanical skin results post-UAL surgery with these devices on the abdomen were not significantly different, although HEUS revealed increased skin firmness. This suggests that HEUS-assisted technology, akin to other devices, is a viable option for UAL procedures.

Effects of aging on the biomechanical properties of the lung extracellular matrix: dependence on tissular stretch.

Introduction: Aging induces functional and structural changes in the lung, characterized by a decline in elasticity and diminished pulmonary remodeling and regenerative capacity. Emerging evidence suggests that most biomechanical alterations in the lung result from changes in the composition of the lung extracellular matrix (ECM), potentially modulating the behavior of pulmonary cells and increasing the susceptibility to chronic lung diseases. Therefore, it is crucial to investigate the mechanical properties of the aged lung. This study aims to assess the mechanical alterations in the lung ECM due to aging at both residual (RV) and functional (FV) lung volumes and to evaluate their effects on the survival and proliferation of mesenchymal stromal cells (MSCs). Methods: The lungs from young (4-6-month-old) and aged (20-24-month-old) mice were inflated with optimal cutting temperature compound to reach FV or non-inflated (RV). ECM proteins laminin, collagen I and fibronectin were quantified by immunofluorescence and the mechanical properties of the decellularized lung sections were assessed using atomic force microscopy. To investigate whether changes in ECM composition by aging and/or mechanical properties at RV and FV volumes affects MSCs, their viability and proliferation were evaluated after 72 h. Results: Laminin presence was significantly reduced in aged mice compared to young mice, while fibronectin and collagen I were significantly increased in aged mice. In RV conditions, the acellular lungs from aged mice were significantly softer than from young mice. By contrast, in FV conditions, the aged lung ECM becomes stiffer than that of in young mice, revealing that strain hardening significantly depends on aging. Results after MSCs recellularization showed similar viability and proliferation rate in all conditions. Discussion: This data strongly suggests that biomechanical measurements, especially in aging models, should be carried out in physiomimetic conditions rather than following the conventional non-inflated lung (RV) approach. The use of decellularized lung scaffolds from aged and/or other lung disease murine/human models at physiomimetic conditions will help to better understand the potential role of mechanotransduction on the susceptibility and progression of chronic lung diseases, lung regeneration and cancer.

Changes in corneal biomechanics in patients with glaucoma: a systematic review and meta-analysis.

INTRODUCTION: Corneal biomechanics has been implicated in a variety of ocular diseases. The purpose of this study was to evaluate the relationship between the glaucoma and corneal biomechanical properties, and exploring the value of corneal biomechanics in the diagnosis and follow-up of glaucoma diseases. METHODS: We searched studies in PubMed, EMBASE, Web of Science and clinicaltrials.gov., as of October 8, 2022. Only English studies were included, without publication time limit. We also searched the reference lists of published reviews. This meta-analysis was conducted with random-effects models, we used mean difference(MD) to evaluate the outcome, and the heterogeneity was assessed with the I2 statistic. Subgroup analyses were performed under the appearance of high heterogeneity. We used 11 items to describe the characteristics of included studies, publication bias was performed through the Egger's test. The quality assessment were evaluated by Newcastle-Ottawa Scale(NOS) items. RESULTS: A total of 27 eligible studies were identified for data synthesis and assessment. The result of meta-analysis showed that in the comparison of included indicators, the corneal biomechanics values of glaucoma patients were statistically lower than those of normal subjects in a similar age range. The covered indicators included central corneal thickness(CCT) (MD = -8.34, 95% CI: [-11.74, -4.94]; P < 0.001), corneal hysteresis(CH)(MD = -1.54, 95% CI: [-1.88, -1.20]; P < 0.001), corneal resistance factor(CRF)( MD = -0.82, 95% CI: [-1.21, -0.44]; P < 0.001), and intraocular pressure(IOP)( corneal-compensated intraocular pressure (IOPcc): MD = 2.45, 95% CI: [1.51, 3.38]; P < 0.001); Goldmann-correlated intraocular pressure (IOPg): MD = 1.30, 95% CI: [0.41, 2.20]; P = 0.004), they all showed statistical difference. While the value of axial length(AL) did not show statistically different(MD = 0.13, 95% CI: [-0.24, 0.50]; P = 0.48). CONCLUSION: Corneal biomechanics are associated with glaucoma. The findings can be useful for the design of glaucoma screening, treatment and prognosis.