Cholesterol accumulation in ovarian follicles causes ovulation defects in Abca1a⁻/⁻ Japanese medaka (Oryzias latipes)

ATP-binding cassette A1 (ABCA1) is a membrane protein, which exports excess cellular cholesterol to generate HDL to reduce the risk of the onset of cardiovascular diseases (CVD). In addition, ABCA1 exerts pleiotropic effects on such as inflammation, tissue repair, and cell proliferation and migration. In this study, we explored the novel physiological roles of ABCA1 using Japanese medaka (Oryzias latipes), a small teleost fish. Three Abca1 genes were found in the medaka genome. ABCA1A and ABCA1C exported cholesterol to generate nascent HDL as human ABCA1 when expressed in HEK293 cells. To investigate their physiological roles, each Abca1-deficient fish was generated using the CRISPR-Cas9 system. Abca1a−/− female medaka was found to be infertile, while Abca1b−/− and Abca1c−/− female medaka were fertile. In vitro ovarian follicle culture suggested that Abca1a deficiency causes ovulation defects. In the ovary, ABCA1A was expressed in theca cells, an outermost layer of the ovarian follicle. Total cholesterol content of Abca1a−/− ovary was significantly higher than that of the wild-type, while estrogen and progestin contents were compatible with those of the wild-type. Furthermore, cholesterol loading to the wild-type follicles caused ovulation defects. These results suggest that ABCA1A in theca cells regulates cholesterol content in the ovarian follicles and its deficiency inhibits successful ovulation through cholesterol accumulation in the ovarian follicle

In vitro osteoclast formation and resorption of silicon-substituted hydroxyapatite ceramics.

Materials that participate in bone remodeling at the implant/tissue interface represent a modern tissue engineering approach with the aim of balancing implant resorption and nascent tissue formation. Silicon-substituted hydroxyapatite (SiHA) ceramics are capable of stimulating new bone formation, but little is known about their interaction with osteoclasts (OC). The effects of soluble silicate and SiHA on OCs were investigated in this study. Soluble silicate below 500 μM did not stimulate cell metabolism at 4 days or alter resorption area at 7 days on calcium phosphate discs. On sintered ceramics, OC numbers were similar on HA, Si0.3 HA (0.5 wt % Si) and Si0.5 HA (1.2 wt % Si) after 21 days in vitro, but actin ring sealing zone morphology on SiHA resembled that commonly found on bone or on carbonate-substituted hydroxyapatite (CHA). Smaller and thicker actin rings on SiHA as compared to HA were probably the result of altered surface chemistry and solubility differences. The more stable sealing zones and increased lattice solubility likely contributed to increased individual pit volumes observed on Si0.5 HA. The delayed formation of OCs on Si0.5 HA (lower numbers at day 14) excludes earlier differentiation as a possible mechanism of increased individual OC pit volumes at later times (day 21). Materials characterization of Si containing biomaterials remains paramount as the Si type and amounts can subsequently impact downstream OC behaviour in a complex manner.Funded by - National Science Foundation Graduate Research Fellowship (RJF). Grant Number: DGE-1042796 - Cambridge International Scholarship from the Cambridge Overseas Trusts (RJF) - National Institute for Health Research (RAB)This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/jbm.a.3547

Design of Titanium Alloys Insensitive to Thermal History for Additive Manufacturing

Powder bed fusion is the most common technology used for 3D printing, where thermal energy is used to selectively melt/sinter granular materials into solid shapes. The build platform is then lowered, more powder is added, and the process is repeated for the next layer to fully print the design. As a result, the built-up part is repeatedly heated. Therefore, materials that are not sensitive to thermal history are preferred for this process. The Ti–Zr system forms a continuous solid solution for both β- and α-phases. The presence of Fe in Ti alloys is inevitable; however, it provides some beneficial effects. The purpose of this work was to prepare Ti–Zr–Fe alloys and investigate their heat treatment behaviour. Ti-xmass%Zr-1mass%Fe alloys (x = 0, 5, 10) were prepared with arc melting. The formation of a solid solution of Zr in Ti was confirmed on the basis of X-ray diffraction peak shifts and hardening effects. A small amount of β-phase precipitation was suggested by the change in electrical resistivity after isothermal ageing at 673 and 773 K. However, no obvious phase or microstructural changes were observed. The laser scanning increased the volume of the precipitates and also coarsened them, but the effect was limited.Ueda M., Ting Hsuan C., Ikeda M., et al. Design of Titanium Alloys Insensitive to Thermal History for Additive Manufacturing. Crystals 13, 568 (2023); https://doi.org/10.3390/cryst13040568

Theory of spin-2 Bose-Einstein condensates: spin-correlations, magnetic response, and excitation spectra

The ground states of Bose-Einstein condensates of spin-2 bosons are classified into three distinct (ferromagnetic, ^^ ^^ antiferromagnetic", and cyclic) phases depending on the s-wave scattering lengths of binary collisions for total-spin 0, 2, and 4 channels. Many-body spin correlations and magnetic response of the condensate in each of these phases are studied in a mesoscopic regime, while low-lying excitation spectra are investigated in the hermodynamic regime. In the mesoscopic regime, where the system is so tightly confined that the spatial degrees of freedom are frozen, the exact, many-body ground state for each phase is found to be expressed in terms of the creation operators of pair or trio bosons having spin correlations. These pairwise and trio-wise units are shown to bring about some unique features of spin-2 BECs such as a huge jump in magnetization from minimum to maximum possible values and the robustness of the minimum-magnetization state against an applied agnetic field. In the thermodynamic regime, where the system is spatially uniform, low-lying excitation spectra in the presence of magnetic field are obtained analytically using the Bogoliubov approximation. In the ferromagnetic phase, the excitation spectrum consists of one Goldstone mode and four single-particle modes. In the antiferromagnetic phase, where spin-singlet ^^ ^^ pairs" undergo Bose-Einstein condensation, the spectrum consists of two Goldstone modes and three massive ones, all of which become massless when magnetic field vanishes. In the cyclic phase, where boson ^^ ^^ trios" condense into a spin-singlet state, the spectrum is characterized by two Goldstone modes, one single-particle mode having a magnetic-field-independent energy gap, and a gapless single-particle mode that becomes massless in the absence of magnetic field.Comment: 28 pages, 4 figure

Estimation of Postcardiac Arrest Interval Based on Atrial Cavity Density in Postmortem Computed Tomography

Background: Intracardiac hypostasis is frequently observed in postmortem computed tomography (PMCT) of acute deaths, and it becomes clearer as the postmortem interval increases. To determine the postcardiac arrest interval (PCAI), we evaluated densities of the right and left atria [anterior part of the right atrium (AR) and posterior part of the left atrium (PL)] using postmortem computed tomographic images. Methods: A total of 184 patients were included in the study. Patients with return of spontaneous circulation and those with final alive confirmation time over 1 hour were excluded. We evaluated the density of AR and PL at the level of the right inferior pulmonary vein entry to the left atrium. We defined the interval between the estimated cardiac arrest time and the postmortem CT time as the PCAI. Results: There was a negative correlation between AR and PCAI in 59 patients who died owing to cardiovascular disease. The regression equation (PCAI = −1.725 × AR + 132.95) was obtained based on this result. There was no correlation between PL and PCAI. Conclusion: The result suggests that the density of the anterior part of the right atrium decreases as postcardiac arrest interval increases in the case of cardiovascular disease. The regression equation may be used as an additional method to estimate postcardiac arrest interval

Exact Eigenstates and Magnetic Response of Spin-1 and Spin-2 Vectorial Bose-Einstein Condensates

The exact eigenspectra and eigenstates of spin-1 and spin-2 vectorial Bose-Einstein condensates (BECs) are found, and their response to a weak magnetic field is studied and compared with their mean-field counterparts. Whereas mean-field theory predicts the vanishing population of the zero magnetic-quantum-number component of a spin-1 antiferromagnetic BEC, the component is found to become populated as the magnetic field decreases. The spin-2 BEC exhibits an even richer magnetic response due to quantum correlation between 3 bosons.Comment: 5 pages, no figures. LaTeX20

Inhibition of Epidermal Growth Factor Receptor and PI3K/Akt Signaling Suppresses Cell Proliferation and Survival through Regulation of Stat3 Activation in Human Cutaneous Squamous Cell Carcinoma

Recent studies have emphasized the important role of Stat3 activation in a number of human tumors from the viewpoint of its oncogenic and antiapoptotic activity. In this study, we examined the role and related signaling molecules of Stat3 in the carcinogenesis of human cutaneous squamous cell carcinoma (SCC). In 35 human cutaneous SCC samples, 86% showed overexpression of phosphorylated (p)-Stat3, and most of those simultaneously overexpressed p-EGFR or p-Akt. Constitutive activation of EGFR and Stat3 was observed in three SCC cell lines and four of five SCC tissues. AG1478, an inhibitor of the EGFR, downregulated Stat3 activation in HSC-1 human SCC cells. AG1478 inhibited cell proliferation and induced apoptosis of HSC-1 cells but did not inhibit the growth of normal human epidermal keratinocytes that did not show Stat3 activation. Furthermore, a PI3K inhibitor also suppressed Stat3 activation in HSC-1 cells to some degree. Combined treatment with the PI3K inhibitor and AG1478 strongly suppressed Stat3 activity and dramatically induced apoptosis of HSC-1 cells. These data suggest that Stat3 activation through EGFR and/or PI3K/Akt activation plays a critical role in the proliferation and survival of human cutaneous SCC

Collective cell migration of Dictyostelium without cAMP oscillations at multicellular stages

In Dictyostelium discoideum, a model organism for the study of collective cell migration, extracellular cyclic adenosine 3’,5’-monophosphate (cAMP) acts as a diffusible chemical guidance cue for cell aggregation, which has been thought to be important in multicellular morphogenesis. Here we revealed that the dynamics of cAMP-mediated signaling showed a transition from propagating waves to steady state during cell development. Live-cell imaging of cytosolic cAMP levels revealed that their oscillation and propagation in cell populations were obvious for cell aggregation and mound formation stages, but they gradually disappeared when multicellular slugs started to migrate. A similar transition of signaling dynamics occurred with phosphatidylinositol 3,4,5-trisphosphate signaling, which is upstream of the cAMP signal pathway. This transition was programmed with concomitant developmental progression. We propose a new model in which cAMP oscillation and propagation between cells, which are important at the unicellular stage, are unessential for collective cell migration at the multicellular stage

Zinc transport via ZNT5-6 and ZNT7 is critical for cell surface glycosylphosphatidylinositol-anchored protein expression

Glycosylphosphatidylinositol (GPI)-anchored proteins play crucial roles in various enzyme activities, cell signaling and adhesion, and immune responses. While the molecular mechanism underlying GPI-anchored protein biosynthesis has been well studied, the role of zinc transport in this process has not yet been elucidated. Zn transporter (ZNT) proteins mobilize cytosolic zinc to the extracellular space and to intracellular compartments. Here, we report that the early secretory pathway ZNTs [ZNT5-ZNT6 heterodimers (ZNT5-6) and ZNT7-ZNT7 homodimers (ZNT7)], which supply zinc to the lumen of the early secretory pathway compartments are essential for GPI-anchored protein expression on the cell surface. We show, using overexpression and gene disruption/re-expression strategies in cultured human cells, that loss of ZNT5-6 and ZNT7 zinc transport functions results in significant reduction in GPI-anchored protein levels similar to that in mutant cells lacking phosphatidylinositol glycan anchor biosynthesis (PIG) genes. Furthermore, medaka fish with disrupted Znt5 and Znt7 genes show touch-insensitive phenotypes similar to zebrafish Pig mutants. These findings provide a previously unappreciated insight into the regulation of GPI-anchored protein expression and protein quality control in the early secretory pathway