Renormalization Group in 2+ϵ2+\epsilon Dimensions and ϵ→2\epsilon\to2: A simple model analysis

Using a simple solvable model, i.e., Higgs--Yukawa system with an infinite number of flavors, we explicitly demonstrate how a dimensional continuation of the $\beta$ function in two dimensional MS scheme {\it fails\/} to reproduce the correct behavior of the $\beta$ function in four dimensions. The mapping between coupling constants in two dimensional MS scheme and a conventional scheme in the cutoff regularization, in which the dimensional continuation of the $\beta$ function is smooth, becomes singular when the dimension of spacetime approaches to four. The existence of a non-trivial fixed point in $2+\epsilon$ dimensions continued to four dimensions $\epsilon\to2$ in the two dimensional MS scheme is spurious and the asymptotic safety cannot be imposed to this model in four dimensions.Comment: 15 pages, PHYZZX. English is improved, some references are adde

Spider silk self-assembly via modular liquid-liquid phase separation and nanofibrillation

クモ糸の階層構造を初めて再現 --シルクタンパク質の液液相分離による階層構造形成--. 京都大学プレスリリース. 2020-11-06.How does the spider spin its self-assembled silk?. 京都大学プレスリリース. 2020-12-01.Spider silk fiber rapidly assembles from spidroin protein in soluble state via an incompletely understood mechanism. Here, we present an integrated model for silk formation that incorporates the effects of multiple chemical and physical gradients on the different spidroin functional domains. Central to the process is liquid-liquid phase separation (LLPS) that occurs in response to multivalent anions such as phosphate, mediated by the carboxyl-terminal and repetitive domains. Acidification coupled with LLPS triggers the swift self-assembly of nanofibril networks, facilitated by dimerization of the amino-terminal domain, and leads to a liquid-to-solid phase transition. Mechanical stress applied to the fibril structures yields macroscopic fibers with hierarchical organization and enriched for β-sheet conformations. Studies using native silk gland material corroborate our findings on spidroin phase separation. Our results suggest an intriguing parallel between silk assembly and other LLPS-mediated mechanisms, such as found in intracellular membraneless organelles and protein aggregation disorders

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events

Pediatric cardiorespiratory failure successfully managed with venoarterial-venous extracorporeal membrane oxygenation: a case report

Background: Venoarterial-venous extracorporeal membrane oxygenation (VAV ECMO) configuration is a combined procedure of extracorporeal membrane oxygenation (ECMO). The proportion of cardiac and respiratory support can be controlled by adjusting arterial and venous return. Therefore, VAV ECMO can be applicable as a bridging therapy in the transition from venoarterial (VA) to venovenous (VV) ECMO. Case presentation: We present an 11-year-old girl with chemotherapy-induced myocarditis requiring extracorporeal cardiorespiratory support. She showed progressive hypotension, tachycardia, hyperlactemia, and tachypnea under support of catecholamines. Echocardiography showed severe left ventricular hypokinesis with an ejection fraction of 30 %. She was placed on VA ECMO with a drainage catheter from the right femoral vein (19.5 Fr) and a return catheter to the right femoral artery (16.5 Fr). Extracorporeal circulation was initiated at a blood flow of 2.0 L/min (59 mL/kg/min). On day 31, although cardiac function had improved, persistent pulmonary failure made weaning from VA ECMO difficult. We planned transition from VA ECMO to VAV ECMO to ensure gradual tapering of extracorporeal cardiac support while evaluating cardiopulmonary function. An additional return cannula (13.5 Fr) was inserted from the right internal jugular vein, which was connected to the circuit branch from the original returning cannula. We then gradually shifted the blood from the femoral artery to the right internal jugular vein over 24 h. She was successfully switched from VA to VV ECMO via VAV ECMO. Conclusions: VAV ECMO might be an option in ensuring oxygenation to the coronary circulation and allowing time to adequately evaluate cardiac function during transition from VA to VV ECMO. Further investigations using larger cohorts are necessary to validate the efficacy of VAV ECMO as a bridging therapy in the transition from VA to VV ECMO.This work was supported by a JSPS KAKENHI Grant (Number JP 16K09541)

Albumin gene targeting in human embryonic stem cells and induced pluripotent stem cells with helper-dependent adenoviral vector to monitor hepatic differentiation

AbstractAlthough progresses in developing differentiation procedures have been achieved, it remains challenging to generate hES/iPS cell-derived mature hepatocytes. We performed knock-in of a monomeric Kusabira orange (mKO1) cassette in the albumin (ALB) gene, in human embryonic stem (hES) cells and induced pluripotent stem (hiPS) cells, with the use of the helper-dependent adenovirus vector (HDAdV). Upon induction into the hepatic lineages, these knock-in hES/iPS cells differentiated into cells that displayed several known hepatic functions. The mKO1 knock-in (ALB/mKo1) hES/hiPS cells were used to visualize hepatic differentiation in vitro. mKO1 reporter expression recapitulated endogenous ALB transcriptional activity. ALB/mKo1 [Hi] population isolated by flow cytometry was confirmed to be enriched with ALB mRNA. Expression profile analyses revealed that characteristic hepatocyte genes and genes related to drug metabolism and many aspects of liver function were highly enriched in the ALB/mKo1 [Hi] population. Our data demonstrate that ALB/mKo1 knock-in hES/iPS cells are valuable resources for monitoring in vitro hepatic differentiation, isolation and analyses of hES and hiPS cells-derived hepatic cells that actively transcribing ALB. These knock-in hES/iPS cell lines could provide further insights into the mechanism of hepatic differentiation and molecular signatures of the hepatic cells derived from hES/iPS cells