Single cell trajectory modeling identifies a primitive trophoblast state defined by BCAM enrichment

The establishment and function of the human placenta is dependent on specialized cells called trophoblasts. Progenitor cytotrophoblasts (CTBs) differentiate along one of two cellular trajectories: the villous or extravillous pathways. CTBs committed to the villous pathway fuse with neighboring CTBs forming the outer multinucleated syncytiotrophoblast layer (SCT), while CTBs committed to the extravillous pathway develop into multi-layered cell columns that anchor the placenta to uterine tissue. At distal column sites, column CTBs differentiate into invasive extravillous trophoblasts (EVT) that facilitate uterine remodeling of spiral arteries and modulate the maternal immune response to fetal antigen. Unfortunately, little is known about the cellular and molecular processes controlling human trophoblast stem cell maintenance and differentiation into these critical trophoblast sub-lineages. To address this, our laboratory established a single cell RNA sequencing (scRNA-seq) dataset from first trimester placentas to identify molecular programs and cell states important in trophoblast progenitor establishment, renewal, and differentiation. Using this dataset, eight distinct trophoblast states were identified, representing progenitor cytotrophoblasts, intermediate column CTBs, syncytiotrophoblast progenitors, and terminally differentiated EVT. Lineage trajectory analysis identified a CTB origin that was reproduced in human trophoblast stem cell organoids. Heightened expression of basal cell adhesion molecule (BCAM) defined this primitive state, where CTBs selected for high levels of surface BCAM expression generated larger clonally-derived organoids than did CTB counterparts expressing lower levels of BCAM. Together, this work resolves complex gene networks within human trophoblast progenitor cells, and identifies BCAM as marker that defines an up-stream progenitor origin.

Morphological characteristics of different types of distal radius die-punch fractures based on three-column theory

Objective The aim of this study is to investigate the morphological characteristics of distal radius die-punch fracture (DRDPF) with different types, based on the three-column theory. Methods The imaging data of 560 patients diagnosed with DRDPF were reviewed and divided into single-column, double-column, or three-column DRDPF according to the three-column theory, and the types, case distribution of DRDPF, and inter- and intra-agreement of classification were further analyzed. Results There were 65 cases of single-column DRDPF, 406 cases of double-column DRDPF, and 89 cases of three-column DRDPF. Among the single-column DRDPF, there were three cases of volar, 13 cases of dorsal, 14 cases of split, and 35 cases of collapse type fractures. Among the radius column fracture, there were 130 cases of metaphseal,155 cases of articular surface, and 210 cases of combined type. The inter-observer Kappa coefficient was 0.877–0.937, and the intra-observer kappa was 0.916–0.959, showing high agreement. At the 12th month’s follow-up, according to the Gartland–Werley score system for the functionary recovery of the wrist and hand, 519 cases (92.68%) of the patients ranked excellent or good, and 41 cases (7.32%) ranked fair. All the cases were fair results, and the intermediate column of the distal radius was collapse type fractures, showing significant difference between the collapse type and other types (χ2 = 23.460, P = 0.000). The excellent and good rate in the single-, double-, and three-column DRDPFs were 93.85%, 92.16%, and 91.01%, respectively (χ2 = 0.018, P = 0.991). Conclusion Due to the difference of the nature and energy of the forces, the position of wrist, and the bone quality of the patients at the moment of the injury, the loading forces transmitted to the intermediate column of the distal radius could result in different types of DRDPF. The classification method in this study included all types of DRDPF, indicating the mechanism, affected sites, and the morphological characteristics of DRDPF with high consistency, which hopefully could provide insight into the treatment and prognosis of DRDPF patients.

Hybrid Simulation of Soil Station System Response to Two-Dimensional Earthquake Excitation

Soil station system seismic issues have been highly valued in recent years. In order to investigate the dynamic seismic behaviors of the intermediate column in soil station systems, a hybrid test of a soil station system was conducted. The soil station model was performed with OpenSees. Virtual hybrid simulation was fulfilled with adapter elements. A hybrid model, composed of the steel column specimen and the remainder numerical model, was assembled using the OpenFresco framework. An intermediate column was treated as the physical substructure, while the rest of the soil station system was treated as the numerical substructure in a hybrid simulation. The hybrid test results are compared with the analytical results. The data obtained from such tests show that the system can accurately reflect the mechanical properties of intermediate columns in soil station systems. A hybrid simulation would be a proper way to assess the seismic performance of a soil station system.

SPRING PLATES IN DISTAL RADIO FRACTURES: “IN VITRO” MECHANICAL PROPERTIES

ABSTRACT Background: Distal radius fractures are one of the most common orthopedic injuries and appear in various patterns. Volar plate fixation is not always considered the gold standard treatment. Objective: To measure the resistance of a fragment-specific fixation assembly model obtained by plate fixation associated with different K-wire sizes. Method: In this original experimental study, novel II, axial compression of bone materials was tested. Results: In both groups, the maximum force supported by the fixation method in our study was ten times greater than the physiological load to which the wrist was subjected under physiological conditions. Discussion: In this study, we obtained encouraging results when compared to results reported in the literature. Our study showed that our bone fixating system was mechanically adequate for articular fractures of the intermediate column of the radius (Melone classification). The results were similar or superior to the results of pressure resistance and stiffness when data from the literature was used as reference. Conclusion: The proposed fixation method demonstrated adequate resistance for fixation of the intermediate column of the distal radius. Increasing K wire size caused augmented resistance of the fixation. Level of Evidence II, Prospective comparative study.

Moment-Rotation Response of Beam-Column Connections in Precast Concrete Structures

This paper provides an experimental investigation on the moment-rotation response of typical moment resisting beam-column connections, employing continuous negative bars consolidated with cast in place concrete over the precast beam and passing through grouted corrugated sleeves into an intermediate column. According to [1], the relative beam-column rotation is highly dependent on the elongation mechanism of the negative bars related to both the embedment length into the grouted sleeves and the development length over the beam end, being also inversely dependent on the vertical distance between the position of the top bars and the centre of rotation at end beam section. The flexural secant stiffness of the moment-rotation response is caused by a sum of the joint opening mechanisms at the beam-column interface and crack propagation within the connection zone, wherein the bond-slip at crack positions occurs prior to the first yielding of the negative bars. Therefore, the semi-rigid behaviour of the beam-column connections is associated with deformation mechanisms that occur at the SLS, but which also affects the global behaviour and stability analysis of precast frames at the ULS.Cruciform tests of full scale beam-column connections were carried out at the Precast Research Centre of the Federal University of Sao Carlos (Brazil), where 6 prototypes were studied varying the detailing of the positive connectors over the concrete corbel. The first pair of connectors employed elastomeric bearing pads with 2 vertical dowel bars, the second pair of connectors employed horizontal joints filled with grout with 2 vertical dowel bars and the last pair of connectors employed positive welded plates. The comparison between the experimental results showed that the smallest secant stiffness, which was obtained from the connector with elastomeric bearing pad, was corresponded to 89% and to 82% of the highest secant stiffness obtained for the connectors with welded plates and grouted joint, respectively. Therefore, the experimental results indicate that the major deformation mechanism within the beam-column connections is mostly dependent on the elongation of the top bars. Finally, a simplified analytical equation has been calibrated against the experimental results of the studied beam-column connections.