Diffusion model predicts the geometry of actin cytoskeleton from cell morphology.

Cells exhibit various morphological characteristics due to their physiological activities, and changes in cell morphology are inherently accompanied by the assembly and disassembly of the actin cytoskeleton. Stress fibers are a prominent component of the actin-based intracellular structure and are highly involved in numerous physiological processes, e.g., mechanotransduction and maintenance of cell morphology. Although it is widely accepted that variations in cell morphology interact with the distribution and localization of stress fibers, it remains unclear if there are underlying geometric principles between the cell morphology and actin cytoskeleton. Here, we present a machine learning system that uses the diffusion model to convert the cell shape to the distribution and alignment of stress fibers. By training with corresponding cell shape and stress fibers datasets, our system learns the conversion to generate the stress fiber images from its corresponding cell shape. The predicted stress fiber distribution agrees well with the experimental data. With this conversion relation, our system allows for performing virtual experiments that provide a visual map showing the probability of stress fiber distribution from the virtual cell shape. Our system potentially provides a powerful approach to seek further hidden geometric principles regarding how the configuration of subcellular structures is determined by the boundary of the cell structure; for example, we found that the stress fibers of cells with small aspect ratios tend to localize at the cell edge while cells with large aspect ratios have homogenous distributions.

Image based cellular contractile force evaluation with small-world network inspired CNN: SW-UNet.

We propose an image based cellular contractile force evaluation method using a machine learning technique. We use a special substrate that exhibits wrinkles when cells grab the substrate and contract, and the wrinkles can be used to visualize the force magnitude and direction. In order to extract wrinkles from the microscope images, we develop a new CNN (convolutional neural network) architecture SW-UNet (small-world U-Net), which is a CNN that reflects the concept of the small-world network. The SW-UNet shows better performance in wrinkle segmentation task compared to other methods: the error (Euclidean distance) of SW-UNet is 4.9 times smaller than the 2D-FFT (fast Fourier transform) based segmentation approach, and is 2.9 times smaller than U-Net. As a demonstration, here we compare the contractile force of U2OS (human osteosarcoma) cells and show that cells with a mutation in the KRAS oncogene show larger force compared to wild-type cells. Our new machine learning based algorithm provides us an efficient, automated and accurate method to evaluate the cell contractile force.

Green Tea Polyphenols Promote Functional Recovery from Peripheral Nerve Injury in Rats.

BACKGROUND Peripheral nerve injury (PNI) is a common and progressive disorder with sensory and motor deficits in the peripheral nervous system (PNS). Treatment is difficult, with unfavorable prognosis. Green tea polyphenols (GTPs) exert neuroprotective effects on regeneration of the central nervous system (CNS). However, the effects of GTPs on functional recovery of the PNS have not been fully characterized. Consequently, the present study investigated the effects of GTPs on nerve regeneration of rats with PNI. MATERIAL AND METHODS The model of PNI was established in rats by sciatic nerve injury (SNI). Adult male Wistar rats with SNI were randomly divided into a vehicle group and a GTPs group. The compound muscle action potential (CMAP) of rat sciatic nerves (SN) was measured using the CM6240 physiological signal acquisition and processing system. The wet weight of the triceps muscle was determined using an analytical balance. The number of myelinated nerve fibers was counted under an optical microscope. Ultrastructure of the regenerated nerves in SN was observed by transmission electron microscopy. The mRNA and protein expression of nerve growth factor (NGF), growth-associated protein-43 (GAP-43), neurofilament 200 (NF200), and myelin-associated glycoprotein (MAG) in SN stumps were measured by real-time quantification PCR (RT-qPCR) and Western blot, respectively. RESULTS In rats with SNI, GTPs relieved the adhesion between nerve anastomosis and surrounding tissues, and significantly increased nerve conduction velocity, wet weight of the triceps muscle, and development and axonal regeneration of myelinated nerve fibers. Moreover, GTPs promoted the mRNA and protein expressions of NGF, GAP-43, NF200, and MAG in SN stumps. CONCLUSIONS GTPs promotes nerve regeneration in rats with SNI.

Longitudinal relations between bullying victimization and aggression: The multiple mediation effects of anger rumination and hostile automatic thoughts.

Bullying victimization is widely accepted to be associated with aggression. However, the mechanisms underlying this relationship remain unknown. To examine the long-term impact of bullying victimization on aggression, the present study tested the potential mediating effects of both anger rumination and hostile automatic thoughts. A total of 809 undergraduates from four universities across China (74.80% female; Mage = 19.63 years, SD = 0.82 years) completed the survey on three occasions, with a 6-month delay between Time 1 and Time 2 and a 1-year interval between Time 2 and Time 3. A cross-lagged model of anger rumination and hostile automatic thoughts was developed to test whether they predicted one another, and two structural models were constructed to test their mediating roles in bullying victimization and aggression. Findings indicated that anger rumination and hostile automatic thoughts are mutually predictable; the correlation between bullying victimization and aggression is mediated independently by anger rumination and hostile automatic thoughts, and the chain mediation of bullying victimization predicting aggression first through anger rumination and then through hostile automatic thinking was established. In addition, an alternative mediation model is also significant, with hostile automatic thoughts as the primary mediator and anger rumination as the secondary mediator. These results highlight the significance of anger rumination and hostile automatic thoughts in the long-term effects of bullying victimization on aggression. Interventions designed to reduce undergraduate students' anger rumination and hostile automatic thoughts may help reduce their aggression.

Evaluation of video-based rPPG in challenging environments: Artifact mitigation and network resilience.

Video-based remote photoplethysmography (rPPG) has emerged as a promising technology for non-contact vital sign monitoring, especially under controlled conditions. However, the accurate measurement of vital signs in real-world scenarios faces several challenges, including artifacts induced by videocodecs, low-light noise, degradation, low dynamic range, occlusions, and hardware and network constraints. In this article, a systematic and comprehensive investigation of these issues is conducted, measuring their detrimental effects on the quality of rPPG measurements. Additionally, practical strategies are proposed for mitigating these challenges to improve the dependability and resilience of video-based rPPG systems. Methods for effective biosignal recovery in the presence of network limitations are detailed, along with denoising and inpainting techniques aimed at preserving video frame integrity. Compared to previous studies, this paper addresses a broader range of variables and demonstrates improved accuracy across various rPPG methods, emphasizing generalizability for practical applications in diverse scenarios with varying data quality. Extensive evaluations and direct comparisons demonstrate the effectiveness of these approaches in enhancing rPPG measurements under challenging environments, contributing to the development of more reliable and effective remote vital sign monitoring technologies.

[Application of reverse traction device in preoperative treatment of high-energy tibial plateau fracture].

Objective: To investigate the effectiveness of the reverse traction device in the preoperative treatment of high-energy tibial plateau fractures. Methods: A retrospective study was conducted to analyze the clinical data of 33 patients with high-energy tibial plateau fractures who met the selection criteria between December 2020 and December 2023. All patients were treated by open reduction and internal fixation. According to the preoperative traction method, they were divided into the observation group (16 cases, treated with a reverse traction device on the day of admission) and the control group (17 cases, treated with heel traction on the day of admission). There was no significant difference in baseline data such as gender, age, body mass index, affected side, cause of injury, fracture Schatzker classification between the two groups ( P>0.05). Preoperative waiting time, preoperative related complications (nail channel loosening, nail channel oozing, nail channel infection, soft tissue necrosis, soft tissue infection, deep vein thrombosis of the lower extremity, etc.), operation time, and total hospitalization time were recorded and compared between the two groups. On the 4th day after traction, visual analogue scale (VAS) score was used to evaluate the pain relief of the patients, the swelling value of the affected limb was measured, and the Immobilization Comfort Questionnaire (ICQ) score was used to evaluate the perioperative hospital comfort of the patients. Results: Both groups of patients completed the operation successfully, and the operation time, total hospitalization time, and preoperative waiting time of the observation group were significantly less than those of the control group ( P<0.05). There was no preoperative related complications in the observation group; in the control group, 3 patients had nail channel loosening and oozing, and 2 cases had the deep vein thrombosis of the lower extremity; the difference in the incidence of complication between the two groups was significant ( P<0.05). On the 4th day after traction, the ICQ score, VAS score, and limb swelling value of the observation group were significantly better than those of the control group ( P<0.05). X-ray films showed that the tibial plateau fracture separation and lower limb alignment recovered after calcaneal traction in the control group, but not as obvious as in the observation group. The fracture gap in the observation group significantly reduced, the tibial plateau alignment was good, and the lateral angulation deformity was corrected. Conclusion: The use of reverse traction treatment in patients with high-energy tibial plateau fractures on admission can accelerate the swelling around the soft tissues to subside, reduce patients' pain, shorten the preoperative waiting time, improve the patients' preoperative quality of life, and contribute to the shortening of the operation time, with a good effectiveness.

[Lateral decubitus position assisted plate internal fixation through a lateral incision to assist reduction combined with intramedullary nail in treatment of complicated subtrochanteric femoral fracture].

Objective: To investigate the effectiveness of lateral decubitus position assisted plate internal fixation through a lateral incision to assist reduction combined with intramedullary nail in the treatment of complicated subtrochanteric femoral fracture. Methods: The clinical data of 16 patients with complicated subtrochanteric femoral fractures (Seinsheimer type Ⅲ-Ⅴ) treated with lateral decubitus position assisted plate internal fixation through a lateral incision to assist reduction combined with intramedullary nail between September 2017 and August 2020 were retrospectively analyzed. There were 13 males and 3 females with an average age of 47 years (range, 26-85 years). There were 12 cases of high-energy injury and 4 cases of low-energy injury. According to Seinsheimer classification, there were 3 cases of type ⅢA, 2 cases of type ⅢB, 7 cases of type Ⅳ, and 4 cases of type Ⅴ. The time from injury to operation ranged from 2 to 6 days, with an average of 4.7 days. The operation time, intraoperative blood loss, postoperative drainage volume, hospitalization stay, surgical complications, fracture healing time, and collodiaphyseal angle of the affected and healthy sides before and after operation were recorded. Hip fracture Harris score was used to evaluate hip function. Results: The operation time was 90-180 minutes (mean, 135.9 minutes), the intraoperative blood loss was 200-400 mL (mean, 288.8 mL), the postoperative drainage volume was 120-220 mL (mean, 140.0 mL), and the hospitalization stay was 12-22 days (mean, 15.8 days). All the 16 patients were followed up 9-12 months (mean, 9.9 months). There was 1 case of incision superficial infection after operation, which healed after anti-infection treatment; no complication such as deep venous thrombosis of lower limbs, coxa vara deformity, re-fracture, or broken nails occurred. All the fractures healed successfully, the healing time ranged from 12 to 20 weeks, with an average of 17.5 weeks. At 6 months after operation, the Harris score was 87-96, with an average of 91.5; the results were excellent in 11 cases and good in 5 cases, with the excellent and good rate of 100%. The collodiaphyseal angle of the affected side was (124.0±5.7)°, while that of the healthy side was (132.0±2.1)°, showing significant difference between the two sides ( t=-7.376, P=0.001). At last follow-up, the collodiaphyseal angle of the affected side was (129.0±3.2)°, which significantly improved when compared with that before operation ( t=-6.175, P=0.002), and there was no significant difference between the affected side and the healthy side ( t=-2.648, P=0.181). Conclusion: Lateral decubitus position assisted plate internal fixation through a lateral incision to assist reduction combined with intramedullary nail is a reliable internal fixation method for the treatment of complicated subtrochanteric femoral fractures. The use of plate reduction is conducive to maintaining the force line of the femoral trochanter. The enlargement of the incision is conducive to the accurate implantation of intramedullary nails without affecting fracture healing.

Wrinkle force microscopy: a machine learning based approach to predict cell mechanics from images.

Combining experiments with artificial intelligence algorithms, we propose a machine learning based approach called wrinkle force microscopy (WFM) to extract the cellular force distributions from the microscope images. The full process can be divided into three steps. First, we culture the cells on a special substrate allowing to measure both the cellular traction force on the substrate and the corresponding substrate wrinkles simultaneously. The cellular forces are obtained using the traction force microscopy (TFM), at the same time that cell-generated contractile forces wrinkle their underlying substrate. Second, the wrinkle positions are extracted from the microscope images. Third, we train the machine learning system with GAN (generative adversarial network) by using sets of corresponding two images, the traction field and the input images (raw microscope images or extracted wrinkle images), as the training data. The network understands the way to convert the input images of the substrate wrinkles to the traction distribution from the training. After sufficient training, the network is utilized to predict the cellular forces just from the input images. Our system provides a powerful tool to evaluate the cellular forces efficiently because the forces can be predicted just by observing the cells under the microscope, which is much simpler method compared to the TFM experiment. Additionally, the machine learning based approach presented here has the profound potential for being applied to diverse cellular assays for studying mechanobiology of cells.

[Comparison of early effectiveness of arthroscopic suture bridge technique and conventional double tunnel suture technique in treatment of avulsion fracture of posterior cruciate ligament insertion].

OBJECTIVE: To compare the early effectiveness of arthroscopic suture bridge technique and conventional double tunnel suture technique in the treatment of avulsion fracture of posterior cruciate ligament (PCL) insertion. METHODS: Between June 2013 and December 2018, 62 patients with tibial avulsion fracture of PCL insertion that met the criteria were selected and randomly divided into trial group (using arthroscopic suture bridge technique) and control group (using conventional double tunnel suture technique), 31 cases in each group. There was no significant difference in gender, age, injured side, cause of injury, time from injury to operation, Meyers & McKeever classification, Kellgren-Lawrence classification, and preoperative knee range of motion, difference of posterior relaxation of bilateral knee joints, International Knee Documentation Committee (IKDC) score, and Lysholm score between the two groups ( P>0.05). The operation time and IKDC score, Lysholm score, knee range of motion, the difference of posterior relaxation of bilateral knee joints (measured by KT-2000 under knee flexion of 90° and 30 lbs) were recorded and compared between the two groups before operation and at 3 and 12 months after operation. RESULTS: Both groups successfully completed the operation, and the operation time of the trial group and the control group were (61.81±6.83) minutes and (80.42±4.22) minutes respectively, showing significant difference between the two groups ( t=12.911, P=0.000). All the incisions healed by first intention, and there was no wound infection and other early postoperative related complications. All patients were followed up 13-18 months (mean, 14.6 months). The fractures in both groups healed at 3 months after operation. No knee pain, limited movement, or other complications occurred. At 3 and 12 months after operation, the IKDC score, Lysholm score, knee range of motion, and the difference of posterior relaxation of bilateral knee joints in both groups were significantly improved when compared with preoperative ones, and further improved at 12 months after operation when compared with at 3 months after operation ( P<0.05). At each time point after operation, the above indexes and the grade of the difference of posterior relaxation of bilateral knee joints in the trial group were significantly better than those in the control group ( P<0.05). CONCLUSION: Arthroscopic suture bridge technique in the treatment avulsion fracture of PCL insertion is simple and reliable, which can significantly improve the function and stability of the knee joint and obtain satisfactory early effectiveness.

[Clinical study on reconstruction of posterior cruciate ligament with platelet rich plasma combined with 3-strand peroneus longus tendons].

OBJECTIVE: To investigate the effectiveness of the reconstruction of posterior cruciate ligament (PCL) with platelet rich plasma (PRP) and 3-strand peroneal longus tendons under arthroscope. METHODS: Between June 2014 and December 2017, 58 patients with PCL rupture were randomly divided into two groups: the trial group (PRP assisted reconstruction of 3-strand peroneal longus tendons) and the control group (4-strand hamstring tendon reconstruction alone), 29 cases in each group. There was no significant difference in gender, age, injury side, Kellgren-Lawrence grade, time from injury to operation, and preoperative American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, International Knee Documentation Committee (IKDC) score, Lysholm score between the two groups ( P>0.05). Before operation, at 3 months and 12 months after operation, the IKDC score and Lysholm score of the two groups were recorded to evaluate the knee joint function, AOFAS ankle-hindfoot score was used to evaluate ankle function; KT-2000 examination (knee flexion of 90°, 30 lbs) was used to evaluate the difference of bilateral knee joint posterior relaxation at 12 months after operation, and MRI was used to evaluate ligament reconstruction; CT was used to evaluate the bone tunnel expansion of femur and tibia at 3 months and 12 months after operation. RESULTS: The operation was completed successfully in both groups, there was no complication in the donor tendon area. All the incisions healed by first intention. All the patients were followed up for more than 1 year. The follow-up time of the trial group was 13-17 months, with an average of 15.0 months; that of the control group was 15-20 months, with an average of 15.4 months. At 3 and 12 months after operation, there was no significant difference in AOFAS ankle-hindfoot score when compared with preoperative score and between the two groups ( P>0.05). At 3 and 12 months after operation, the IKDC score and Lysholm score of the two groups were significantly improved, and further improvement was found at 12 months when compared with at 3 months ( P<0.05); the scores in the trial group were significantly better than those of the control group ( P<0.05). At 12 months after operation, the difference of the posterior relaxation of the bilateral knees in the trial group was less than 5 mm in 27 cases, 6-10 mm in 2 cases; in the control group was less than 5 mm in 20 cases, 6-10 mm in 6 cases, and >10 mm in 3 cases; the difference between the two groups was not significant ( Z=0.606, P=0.544). At 12 months after operation, MRI of knee joint showed that all patients had good PCL graft. The MRI score of the trial group was better than that of the control group ( t=2.425, P=0.019). CT examination at 3 and 12 months after operation showed that the bone tunnel expansion of femur and tibia in the trial group were significantly better than those in the control group ( P<0.05). CONCLUSION: PRP combined with 3-stand peroneal longus tendons can significantly improve the function and stability of knee joint, effectively promote graft remodeling, and promote tendon bone healing, reduce the expansion of bone tunnel. The effectiveness is satisfactory.

[Arthroscopy-assisted treatment of severe comminuted distal radial fracture using external fixators].

OBJECTIVE: To evaluate the outcomes of arthroscopy-assisted treatment of severe comminuted distal radial fracture with external fixators and kirschner wire fixation. METHODS: Twenty-seven cases of severe comminuted distal radial fracture treated between March, 2010 and January, 2012 were reviewed. During the operation, the carpal joint space was expanded with the external fixator, and the fracture was fixed by Kirschner wire after open reduction. The carpal joint was observed intraoperatively with arthroscopy to ensure full reduction, and the distal posterior interosseous nerve was then severed. The results of postoperative X-ray and wrist functional status of the carpal joints were recorded. Another 27 cases of severe comminuted distal radial fracture treated by conventional surgical approach served as the control group. RESULTS: The patients were followed up for a mean of 13.2 (5-27) months. Compared with the conventional surgical approach, arthroscopy-assisted treatment resulted in a significantly shorter operative time with better appearance of the articular surface and also better wrist function assessed using the Krimmer system (P<0.05). CONCLUSION: Arthroscopy-assisted external fixator treatment is effective for management of severe comminuted distal radial fracture and avoids the stair-like appearance of the articular surface to achieve the maximal functional recovery of the carpal joints and reduce traumatic arthritis.