Search

Abstract Background Femoral neck fractures are a common traumatic injury. The removal of the internal fixation remains controversial, especially in terms of mechanical stability. Moreover, collapsed necrosis of the femoral head continues to occur after fracture healing. We believe that sclerotic cancellous bone (SCB) formation around the screw is associated with femoral head necrosis. We aimed to compare mechanical features before and after implant removal and determine the effect of SCB formation on stress distribution. Methods Cylindrical cancellous bone sections were collected from a relatively normal region and an SCB region of a necrotic femoral head, and their elastic moduli were measured. Four femoral finite element models were developed: a) femoral neck fracture healing with implants, b) fracture healing without implants, c) sclerosis around the screw with implants, and d) sclerosis around the screw without implants. Results The maximum von Mises peak stresses of models a and b were 66.643 MPa and 63.76 MPa, respectively, and were concentrated in the upper lateral femur. The main stress was scattered at the lowest screw tail, femoral calcar region, and lateral femur shaft. Moreover, coronal plane strain throughout the screw paths near the femoral head in models a and b was mostly in the range of 1000–3000 με. The maximum stress concentrations in models c and d were located at the lower femoral head and reached 91.199 MPa and 78.019 MPa, respectively. Conclusions The stresses in the sclerotic model around the cannulated screws are more concentrated on the femoral head than in the healing model without sclerotic bone. The overall stresses in the healing femoral neck fracture model were essentially unchanged before and after removal of the internal fixation.

To investigate the dynamic tensile properties and energy dissipation characteristics of marble in three different conditions: dry, water-saturated, and oil-saturated, a Brazilian disk splitting test was conducted using a 50 mm diameter Hopkinson pressure bar (SHPB) device. The findings indicate that the peak strain and dynamic tensile strength of the three conditions increase with strain rate, exhibiting a clear strain rate effect. Additionally, lubricating effects of water and oil weaken internal shear sliding friction, thus promoting crack expansion. Furthermore, immersion of fluid in marble weakens the cementation of internal mineral particles, leading to lower tensile strength of marble saturated with water and oil compared to dry marble under dynamic impact. When analyzing the energy dissipation of marble, both the absorption energy and dissipation energy density increase with oil strain rate, indicating a positive correlation. Moreover, numerical results obtained from ANSYS/LS-DYNA correspond well with experimental data, thus verifying and interpreting the experimental outcomes.

The Huashi Baidu Formula (HSBDF), a key Chinese medical drug, has a remarkable clinical efficacy in treating acute lung injury (ALI), and it has been officially approved by the National Medical Products Administration of China for drug clinical trials. Nevertheless, the regulated mechanisms of HSBDF and its active compounds in plasma against ALI were rarely studied. Based on these considerations, the key anti-inflammatory compounds of HSBDF were screened by molecular docking and binding free energy. The key compounds were further identified in plasma by LC/MS. Network pharmacology was employed to identify the potential regulatory mechanism of the key compounds in plasma. Next, the network pharmacological prediction was validated by a series of experimental assays, including CCK-8, EdU staining, test of TNF-α, IL-6, MDA, and T-SOD, and flow cytometry, to identify active compounds. Molecular dynamic simulation and binding interaction patterns were used to evaluate the stability and affinity between active compounds and target. Finally, the active compounds were subjected to predict pharmacokinetic properties. Molecular docking revealed that HSBDF had potential effects of inhibiting inflammation by acting on IL-6R and TNF-α. Piceatannol, emodin, aloe-emodin, rhein, physcion, luteolin, and quercetin were key compounds that may ameliorate ALI, and among which, there were five compounds (emodin, aloe-emodin, rhein, luteolin, and quercetin) in plasma. Network pharmacology results suggested that five key compounds in plasma likely inhibited ALI by regulating inflammation and oxidative damage. Test performed in vitro suggested that HSBDF (0.03125 mg/ml), quercetin (1.5625 μM), emodin (3.125 μM), and rhein (1.5625 μM) have anti-inflammatory function against oxidative damage and decrease apoptosis in an inflammatory environment by LPS-stimulation. In addition, active compounds (quercetin, emodin, and rhein) had good development prospects, fine affinity, and stable conformations with the target protein. In summary, this study suggested that HSBDF and its key active components in plasma (quercetin, emodin, and rhein) can decrease levels of pro-inflammatory factors (IL-6 and TNF-α), decrease expression of MDA, increase expression of T-SOD, and decrease cell apoptosis in an inflammatory environment. These data suggest that HSBDF has significant effect on anti-inflammation and anti-oxidative stress and also can decrease cell apoptosis in treating ALI. These findings provided an important strategy for developing new agents and facilitated clinical use of HSBDF against ALI.

Somatic embryogenesis (SE) is an ideal model for plant cell totipotency. Transition from somatic cells to embryogenic cells is the key to SE. The poor frequency of embryogenic callus (EC) induction has limited the application of SE in many plants, such as Agapanthus praecox. We performed large-scale, quantitative proteomic and metabolomic analyses with different callus differentiation directions (SE and organogenesis) and stages (initial SE and repetitive SE) to better understand the morphological, physiological, and molecular characteristics of the acquisition of embryogenic ability in A. praecox. Integrated proteomic and metabolomic analyses suggested that callus differentiation direction was potentially regulated by pathways related to carbohydrate and energy metabolism (fatty acid metabolism, pyruvate metabolism, glycolysis/gluconeogenesis, pentose and glucuronate interconversions, starch and sucrose metabolism, galactose metabolism, carbon fixation pathways in prokaryotes, carbohydrate digestion and absorption, and fructose and mannose metabolism), chromatin accessibility and DNA methylation, reactive oxygen species responses and resistance (ascorbate and aldarate metabolism), and plant hormonal signaling. As a validation, we found that carbon source combination and plant hormone regulation in the culture medium significantly affected the acquisition of embryogenic ability, thereby inducing EC. Interestingly, plant hormonal signaling-related genes showed different expression patterns significantly when callus cultured with different carbon sources. Thus, our results suggested that energy supply and hormone signal transduction seemed to cooperatively contribute to the activation of embryogenic ability. Altogether, this study revealed valuable information regarding the molecular and biochemical changes that occurred during EC induction and provided valuable foundation for comprehensive understanding of the mechanisms associated with SE and organogenesis in A. praecox.

Abstract Background Bone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions. The stress and strain distribution and fluid flow in bone play an important role in the realization of mechanotransduction and bone remodeling. Methods To investigate the mechanotransduction and fluid behaviors in loaded bone, a multiscale method was developed. Based on poroelastic theory, we established the theoretical and FE model of a segment bone to provide basis for researching more complex bone model. The COMSOL Multiphysics software was used to establish different scales of bone models, and the properties of mechanical and fluid behaviors in each scale were investigated. Results FE results correlated very well with analytical in macroscopic scale, and the results for the mesoscopic models were about less than 2% different compared to that in the macro–mesoscale models, verifying the correctness of the modeling. In macro–mesoscale, results demonstrated that variations in fluid pressure (FP), fluid velocity (FV), von Mises stress (VMS), and maximum principal strain (MPS) in the position of endosteum, periosteum, osteon, and interstitial bone and these variations can be considerable (up to 10, 8, 4 and 3.5 times difference in maximum FP, FV, VMS, and MPS between the highest and the lowest regions, respectively). With the changing of Young’s modulus (E) in each osteon lamella, the strain and stress concentration occurred in different positions and given rise to microscale spatial variations in the fluid pressure field. The heterogeneous distribution of lacunar–canalicular permeability (k lcp) in each osteon lamella had various influence on the FP and FV, but had little effect on VMS and MPS. Conclusion Based on the idealized model presented in this article, the presence of endosteum and periosteum has an important influence on the fluid flow in bone. With the hypothetical parameter values in osteon lamellae, the bone material parameters have effect on the propagation of stress and fluid flow in bone. The model can also incorporate alternative material parameters obtained from different individuals. The suggested method is expected to provide dependable biological information for better understanding the bone mechanotransduction and signal transduction.

Transgression and regression deposits from the shallow continental margin provide information on orbital-scale variations in sea level, climate change, and local tectonics. In this study, we conduct a high-resolution chronological and sedimentological analysis of a 125-m core (NHH01) drilled in the southern Yellow Sea. We developed a high-resolution age model at the orbital timescale over the last ∼1 Myr by the astronomical tuning of the sediment grain size. Sedimentological analysis and environmental proxies reveal that the study area is characterized by cyclic alternations of neritic and littoral/fluvial deposits controlled by glacial–interglacial sea-level changes. These results confirm the earlier assumption that sea-level fluctuations play a dominant role in the sedimentary architecture of the southern Yellow Sea. Moreover, only low-frequency sea-level fluctuations (∼100 kyr) were preserved in the NHH01 sequence; however, additional high-frequency (∼40 kyr) sea-level variations were also present in the sediments of the shallower Bohai Sea. Despite the large spatial difference, this finding implies that the sedimentary environment in the eastern marginal seas of China had been influenced by the sea level as a whole over the last 1 Myr. The comparison of the sedimentary environment with other cores from the Bohai Sea, Yellow Sea, and coastal region, as well as records from Indonesia and Japan, reveals that a consistent initiation of large-scale marine transgression occurred at ∼0.8–1 Ma. This phenomenon was likely caused by the long duration of glacio-eustatic high sea-level stands following the Middle Pleistocene transition, which is characterized by a shift in glacial cycles from 40 to 100 kyr.

Coastal vegetation both mitigates the damage inflicted by marine disasters on coastal areas and plays an important role in the global carbon cycle (i.e., blue carbon). Nevertheless, detailed records of changes in coastal vegetation composition and diversity in the Holocene, coupled with climate change and river evolution, remain unclear. To explore vegetation dynamics and their influencing factors on the coastal area of the Bohai Sea (BS) during the Holocene, we present high-resolution pollen and sediment grain size data obtained from a sediment core of the BS. The results reveal that two rapid and abrupt changes in salt marsh vegetation are linked with the river system changes. Within each event, a recurring pattern – starting with a decline in Cyperaceae, followed by an increase in Artemisia and Chenopodiaceae – suggests a successional process that is determined by the close relationship between Yellow River (YR) channel shifts and the wetland community dynamics. The phreatophyte Cyperaceae at the base of each sequence indicate lower saline conditions. Unchannelized river flow characterized the onset of the YR channel shift, caused a huge river-derived sediment accumulation in the floodplain and destroyed the sedges in the coastal depression. Along with the formation of a new channel, lateral migration of the lower channel stopped, and a new intertidal mudflat was formed. Pioneer species (Chenopodiaceae, Artemisia) were the first to colonize the bare zones of the lower and middle marsh areas. In addition, the pollen results revealed that the vegetation of the BS land area was dominated by broadleaved forests during the Early Holocene (8500–6500 BP) and by conifer and broadleaved forests in the Middle Holocene (6500–3500 BP), which was followed by an expansion of broadleaved trees (after 3500 BP). The pollen record indicated that a warmer Early and Late Holocene and colder Middle Holocene were consistent with previously reported temperature records for East Asia. The main driving factors of temperature variation in this region are insolation, the El Niño–Southern Oscillation and greenhouse gases forcing. [ABSTRACT FROM AUTHOR]