Master regulators of the epithelial-mesenchymal transition such as Twist1 and Snail1 have been implicated in invasiveness and the generation of cancer stem cells, but their persistent activity ...inhibits stem-cell-like properties and the outgrowth of disseminated cancer cells into macroscopic metastases. Here, we show that Twist1 activation primes a subset of mammary epithelial cells for stem-cell-like properties, which only emerge and stably persist following Twist1 deactivation. Consequently, when cells undergo a mesenchymal-epithelial transition (MET), they do not return to their original epithelial cell state, evidenced by acquisition of invasive growth behavior and a distinct gene expression profile. These data provide an explanation for how transient Twist1 activation may promote all steps of the metastatic cascade; i.e., invasion, dissemination, and metastatic outgrowth at distant sites.
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•Transient Twist1 activation primes cells for stem-cell-like traits•Stable stem-cell-like traits arise after Twist1 deactivation•Transient, not continuous, Twist1 activity promotes invasive growth•Transient Twist1 elicits a stably altered plastic epithelial cell state
Schmidt et al. show that Twist1, a master regulator of the epithelial-mesenchymal transition, primes mammary epithelial cells for stem-cell-like properties. Following transient Twist1 activation, cells display an altered, epithelial cell state characterized by invasive growth, plasticity, and a unique gene expression profile.
We present an organoid regeneration assay in which freshly isolated human mammary epithelial cells are cultured in adherent or floating collagen gels, corresponding to a rigid or compliant matrix ...environment. In both conditions, luminal progenitors form spheres, whereas basal cells generate branched ductal structures. In compliant but not rigid collagen gels, branching ducts form alveoli at their tips, express basal and luminal markers at correct positions, and display contractility, which is required for alveologenesis. Thereby, branched structures generated in compliant collagen gels resemble terminal ductal-lobular units (TDLUs), the functional units of the mammary gland. Using the membrane metallo-endopeptidase CD10 as a surface marker enriches for TDLU formation and reveals the presence of stromal cells within the CD49f(hi)/EpCAM(-) population. In summary, we describe a defined in vitro assay system to quantify cells with regenerative potential and systematically investigate their interaction with the physical environment at distinct steps of morphogenesis.
Basic helix-loop-helix transcription factor Twist1 is a master regulator of Epithelial-Mesenchymal Transition (EMT), a cellular program implicated in different stages of development as well as ...metastatic dissemination of carcinomas. Here, we show that Twist1 requires TGF-beta type-I receptor (TGFBR1)-activation to bind an enhancer region of downstream effector ZEB1, thereby inducing ZEB1 transcription and EMT. When TGFBR1-phosphorylation is inhibited, Twist1 generates a distinct cell state characterized by collective invasion, simultaneous proliferation and expression of endothelial markers. By contrast, TGFBR1-activation directs Twist1 to induce stable mesenchymal transdifferentiation through EMT, thereby generating cells that display single-cell invasion, but lose their proliferative capacity. In conclusion, preventing Twist1-induced EMT by inhibiting TGFβ-signaling does not generally block acquisition of invasion, but switches mode from single-cell/non-proliferative to collective/proliferative. Together, these data reveal that transient Twist1-activation induces distinct cell states depending on signaling context and caution against the use of TGFβ-inhibitors as a therapeutic strategy to target invasiveness.
BioMAX is the first macromolecular crystallography beamline at the MAX IV Laboratory 3 GeV storage ring, which is the first operational multi‐bend achromat storage ring. Due to the low‐emittance ...storage ring, BioMAX has a parallel, high‐intensity X‐ray beam, even when focused down to 20 µm × 5 µm using the bendable focusing mirrors. The beam is tunable in the energy range 5–25 keV using the in‐vacuum undulator and the horizontally deflecting double‐crystal monochromator. BioMAX is equipped with an MD3 diffractometer, an ISARA high‐capacity sample changer and an EIGER 16M hybrid pixel detector. Data collection at BioMAX is controlled using the newly developed MXCuBE3 graphical user interface, and sample tracking is handled by ISPyB. The computing infrastructure includes data storage and processing both at MAX IV and the Lund University supercomputing center LUNARC. With state‐of‐the‐art instrumentation, a high degree of automation, a user‐friendly control system interface and remote operation, BioMAX provides an excellent facility for most macromolecular crystallography experiments. Serial crystallography using either a high‐viscosity extruder injector or the MD3 as a fixed‐target scanner is already implemented. The serial crystallography activities at MAX IV Laboratory will be further developed at the microfocus beamline MicroMAX, when it comes into operation in 2022. MicroMAX will have a 1 µm × 1 µm beam focus and a flux up to 1015 photons s−1 with main applications in serial crystallography, room‐temperature structure determinations and time‐resolved experiments.
BioMAX is the first macromolecular crystallography beamline at the first fourth‐generation storage ring, the 3 GeV storage ring at MAX IV Laboratory. It is a highly automated, user‐friendly, microfocus beamline that provides excellent performance for most macromolecular crystallography applications.
Redirected walking techniques allow people to walk in a larger virtual space than the physical extents of the laboratory. We describe two experiments conducted to investigate human sensitivity to ...walking on a curved path and to validate a new redirected walking technique. In a psychophysical experiment, we found that sensitivity to walking on a curved path was significantly lower for slower walking speeds (radius of 10 m versus 22 m). In an applied study, we investigated the influence of a velocity-dependent dynamic gain controller and an avatar controller on the average distance that participants were able to freely walk before needing to be reoriented. The mean walked distance was significantly greater in the dynamic gain controller condition, as compared to the static controller (22 m versus 15 m). Our results demonstrate that perceptually motivated dynamic redirected walking techniques, in combination with reorientation techniques, allow for unaided exploration of a large virtual city model.
Over the last decade, serial crystallography, a method to collect complete diffraction datasets from a large number of microcrystals delivered and exposed to an X‐ray beam in random orientations at ...room temperature, has been successfully implemented at X‐ray free‐electron lasers and synchrotron radiation facility beamlines. This development relies on a growing variety of sample presentation methods, including different fixed target supports, injection methods using gas‐dynamic virtual‐nozzle injectors and high‐viscosity extrusion injectors, and acoustic levitation of droplets, each with unique requirements. In comparison with X‐ray free‐electron lasers, increased beam time availability makes synchrotron facilities very attractive to perform serial synchrotron X‐ray crystallography (SSX) experiments. Within this work, the possibilities to perform SSX at BioMAX, the first macromolecular crystallography beamline at MAX IV Laboratory in Lund, Sweden, are described, together with case studies from the SSX user program: an implementation of a high‐viscosity extrusion injector to perform room temperature serial crystallography at BioMAX using two solid supports – silicon nitride membranes (Silson, UK) and XtalTool (Jena Bioscience, Germany). Future perspectives for the dedicated serial crystallography beamline MicroMAX at MAX IV Laboratory, which will provide parallel and intense micrometre‐sized X‐ray beams, are discussed.
The possibilities to perform serial synchrotron crystallography at BioMAX, the first macromolecular crystallography beamline at MAX IV Laboratory in Lund, Sweden, are described, together with case studies from the synchrotron X‐ray crystallography user program.
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► We investigate distance perception in three large screen immersive displays (LSIDs). ► Verbal reports of egocentric distances are nearly veridical in the real world. ► Verbal ...reports of egocentric distances are underestimated in all three LSIDs. ► We found an effect of distance in the real and virtual worlds. ► Stereoscopic projection impacts only near (2m) distance estimates.
Many scientists have demonstrated that compared to the real world egocentric distances in head-mounted display virtual environments are underestimated. However, distance perception in large screen immersive displays has received less attention. We investigate egocentric distance perception in a virtual office room projected using a semi-spherical, a Max Planck Institute CyberMotion Simulator cabin and a flat large screen immersive display. The goal of our research is to systematically investigate distance perception in large screen immersive displays with commonly used technical specifications. We specifically investigate the role of distance to the target, stereoscopic projection and motion parallax on distance perception. We use verbal reports and blind walking as response measures for the real world experiment. Due to the limited space in the three large screen immersive displays we use only verbal reports as the response measure for the experiments in the virtual environment. Our results show an overall underestimation of distance perception in the large screen immersive displays, while verbal estimates of distances are nearly veridical in the real world. We find that even when providing motion parallax and stereoscopic depth cues to the observer in the flat large screen immersive display, participants estimate the distances to be smaller than intended. Although stereo cues in the flat large screen immersive display do increase distance estimates for the nearest distance, the impact of the stereoscopic depth cues is not enough to result in veridical distance perception. Further, we demonstrate that the distance to the target significantly influences the percent error of verbal estimates in both the real and virtual world. The impact of the distance to the target on the distance judgments is the same in the real world and in two of the used large screen displays, namely, the MPI CyberMotion Simulator cabin and the flat displays. However, in the semi-spherical display we observe a significantly different influence of distance to the target on verbal estimates of egocentric distances. Finally, we discuss potential reasons for our results. Based on the findings from our research we give general suggestions that could serve as methods for improving the LSIDs in terms of the accuracy of depth perception and suggest methods to compensate for the underestimation of verbal distance estimates in large screen immersive displays.
Master regulators of the epithelial-mesenchymal transition such as Twist1 and Snail1 have been implicated in invasiveness and the generation of cancer stem cells, but their persistent activity ...inhibits stem-cell-like properties and the outgrowth of disseminated cancer cells into macroscopic metastases. Here, we show that Twist1 activation primes a subset of mammary epithelial cells for stem-cell-like properties, which only emerge and stably persist following Twist1 deactivation. Consequently, when cells undergo a mesenchymal-epithelial transition (MET), they do not return to their original epithelial cell state, evidenced by acquisition of invasive growth behavior and a distinct gene expression profile. These data provide an explanation for how transient Twist1 activation may promote all steps of the metastatic cascade;i.e.,invasion, dissemination, and metastatic outgrowth at distant sites.
Objectives: To evaluate the clinical long-term course in patients with chronic granulomatous disease (CGD) with respect to different CGD subtypes and currently used antimicrobial prophylactic ...measures. Study design: The records of 39 patients with CGD who were monitored during a period of 22 years were reviewed. All infections, infectious complications, and clinical outcomes were documented for a total observation period of 610 patient-years and were stratified with respect to different CGD subtypes. Results: Lymphadenitis, skin abscesses, and pneumonia occurred in 87%, 72%, and 59% of the patients, respectively. In 151 microbiologic isolates Staphylococcus aureus , Aspergillus species, Candida species, Pseudomonas species, and Salmonella species were the most frequently detected microorganisms. There were 167 severe infections requiring hospitalization and intravenous antimicrobial treatment, resulting in an incidence of 3.7 severe infections per 100 patient months (SI/100 PM). Long-term antibiotic prophylaxis significantly reduced the incidence of severe bacterial infections from 4.8 SI/100 PM to 1.6 SI/100 PM (P =.0035). In contrast, fungal infections increased under antibiotic prophylaxis from a mean incidence of 0.2 SI/100 PM to 1.9 SI/100 PM (P =.04). We found a 50% survival rate through the fourth decade of life, with a plateau after the third decade of life. Patients with a complete absence of cytochrome b558 showed an earlier manifestation of their disease and a higher incidence of infections and had significant lower survival than patients with only diminished cytochrome b558 or autosomal recessive CGD. Conclusions: Infections with Aspergillus species have become the major cause of infectious complications and death in patients with CGD. Prophylactic and therapeutic measures are needed to further increase life expectancy and quality for patients with CGD. (J Pediatr 2000;137:687-93)
The aim of Redirected Walking (RDW) is to redirect a person along their path of travel in a Virtual Environment (VE) in order to increase the virtual space that can be explored in a given tracked ...area. Among other techniques, the user is redirected on a curved real-world path while visually walking straight in the VE (curvature gain). In this paper, we describe two experiments we conducted to test and extend RDW techniques. In Experiment 1, we measured the effect of walking speed on the detection threshold for curvature of the walking path. In a head-mounted display (HMD) VE, we found a decreased sensitivity for curvature for the slowest walking speed. When participants walked at 0.75 m/s, their detection threshold was approximately 0.1m -1 (radius of approximately 10m). In contrast, for faster walking speeds (>;1.0m/s), we found a significantly lower detection threshold of approximately 0.036m -1 (radius of approximately 27m). In Experiment 2, we implemented many well known redirection techniques into one dynamic RDW application. We integrated a large virtual city model and investigated RDW for free exploration. Further, we implemented a dynamic RDW controller which made use of the results from Experiment 1 by dynamically adjusting the applied curvature gain depending on the actual walking velocity of the user. In addition, we investigated the possible role of avatars to slow the users down or make them rotate their heads while exploring. Both the dynamic curvature gain controller and the avatar controller were evaluated in Experiment 2. We measured the average distance that was walked before reaching the boundaries of the tracked area. The mean walked distance was significantly larger in the condition where the dynamic gain controller was applied. This distance increased from approximately 15m for static gains to approximately 22m for dynamic gains. This did not come at the cost of an increase in simulator sickness. Applying the avatar controller did reveal an effect on walking distance or simulator sickness.
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