Structure of six-transmembrane cation channels revealed by single-particle analysis from electron microscopic images

Single-particle analysis is a computer-aided method for determining protein structure using projection images obtained by electron microscopy. Recently reconstructed 6-TM-type cation channels demonstrate the structural similarities and divergence of the family

Critical Nature of the Size Exponent of Polymers

On the basis of the thermodynamic theory of the excluded volume effects, we show that the size exponent varies abruptly, depending on the change of the segment concentration. For linear polymers, the exponent changes discontinuously from $\nu=3/5$ for the isolated system ($\bar{\phi}=0$) in good solvents to $\nu=1/2$ in the finite concentration ($0<\bar{\phi}\le1$), while for branched polymers having $\nu_{0}=1/4$, the corresponding exponent varies from $\nu=1/2$ ($\bar{\phi}=0$) to $\nu\cong 1/3$ ($0<\bar{\phi}\le1$).Comment: 10 pages, 10 figure

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Concurrent Connection of Embryonic Chick Heart Using a Microfluidic Device for Organ-Explant-Chip

AbstractWe propose a concurrent microvascular connection method called suction-induced vascular fixation (SVF) method for the achievement of Organ-Explant-Chip which is a biologically-designed simulator having biological materials such as cells, tissues, and organs. The advantages of proposed method with using a microfluidic device are as follows: (1) operation of flexible objects (blood vessels), (2) alignment the blood vessels concurrently, and (3) reduction of the DOFs of the blood vessels. From the experimental results, we confirmed that four cardiovascular of the explanted embryonic chick heart can be induced into the fabricated microfluidic device concurrently. We have also succeeded in construction of hybrid circulatory system between artifacts and embryonic chick heart, and monitoring the response of the heart of chick embryo by supplying the culture medium

Reconstruction of the P2X2 Receptor Reveals a Vase-Shaped Structure with Lateral Tunnels above the Membrane

SummaryIn response to the intercellular messenger ATP, P2X receptors transfer various sensory information, including pain. Here we have reconstructed the structure of the P2X2 receptor at 15 Å resolution from more than 90,000 particle images, taken with a cryo-electron microscope equipped with a helium-cooled stage. This three-dimensional depiction, presumably in a closed state, revealed an elongated vase-shaped structure 202 Å in height and 160 Å in major diameter. The extracellular and transmembrane domains present a two-layered structure, in which a sparse outer layer surrounds a pore-forming inner density. The decreased diameter of a putative ion-conducting pathway at the middle of the membrane was considered to be the narrowest part of the pore, which has been predicted from electrophysiological studies. The sparse, extended structure of the P2X2 receptor indicates a loose assembly of subunits, which could be a basis for the activation-dependent pore dilation of P2X receptors

How do we manage the gastrectomy for gastric cancer after coronary artery bypass grafting using the right gastroepiploic artery? Report of two cases and a review of the literature

<p>Abstract</p> <p>Background</p> <p>Recently, the right gastroepiploic artery (RGEA) has been used in coronary artery bypass grafting (CABG) as an alternative arterial graft. Unfortunately, an increased incidence of gastric cancers has been reported after CABG using the RGEA. Handling of the RGEA during gastrectomy in these patients may cause lethal complications, which sometimes reduces the feasibility of curative dissection of lymph nodes at the base of the graft.</p> <p>Case presentations</p> <p>We describe two cases of gastric cancer undergoing gastrectomy after CABG with the use of RGEA. To avoid the potentially fatal coronary event during gastrectomy, safe handling of the conduit including preparations for injuries and prevention of vessel spasm was performed in both cases, accompanied by an adequate monitoring of the systemic circulation. Intraoperative frozen section examination showed no lymph node metastasis around the graft in any of the cases; therefore, complete lymph node dissection at the base of the graft was not undertaken. No complications occurred during the operation. In addition to these two cases, twenty-four cases reported in the literatures were reviewed (a total of 26 cases). Ten early and 16 advanced gastric cancers were included. Among the 16 advanced gastric cancer cases, an alternative graft was employed in 8 due to the resection of an original graft to complete lymph node dissection. Mere handling of a graft often caused lethal complications suggesting that the operation should be completed by isolation of the graft. A pedicled graft harvesting via the ante-gastric route was popular. However, a skeletonized harvesting with resection of the pyloric branches of the RGEA would be better because this would interrupt the original lymph flow, which could eliminate the need for lymph node dissection and graft isolation. Among the 10 cases having early gastric cancers, 6 were found within 1.5 years after CABG. Early detection in these 6 cases was possible due to the use of gastric fiberscopic examination before and after CABG, which gave them opportunities to receive a less extensive operation such as endoscopic mucosal resection.</p> <p>Conclusion</p> <p>Adequate intraoperative care as well as an optimal lymph node dissection considering the graft harvesting method at the first CABG leads to successful gastrectomy after CABG using the RGEA graft. Therefore, this operation should be carried out with careful management by both gastrointestinal and cardiovascular surgeons.</p

Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System

Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields