Self-sustaining oscillation of two axonemal microtubules based on a stochastic bonding model between microtubules and dynein

The motility of cilia and flagella plays important physiological roles, and there has been a great deal of research on the mechanisms underlying the motility of molecular motors. Although recent molecular structural analyses have revealed the components of the ciliary axoneme, the mechanisms involved in the regulation of dynein activity are still unknown, and how multiple dyneins coordinate their movements remains unclear. In particular, the mode of binding for axonemal dynein has not been elucidated. In this study, we constructed a thermodynamic stochastic model of microtubule-dynein coupling and reproduced the experiments of Aoyama and Kamiya on the minimal component of axonemal microtubule-dynein. We then identified the binding mode of axonemal dynein and clarified the relationship between dynein activity distribution and axonemal movement. Based on our numerical results, the slip-bond mechanism agrees quantitatively with the experimental results in terms of amplitude, frequency, and propagation velocity, implying that axial microtubule-dynein coupling may follow a slip-bond mechanism. Moreover, the frequency and propagation velocity decayed in proportion to the fourth power of microtubule length, and the critical load of the trigger for the oscillation agreed well with Euler's critical load.

Multicenter prospective trial of total gastrectomy versus proximal gastrectomy for upper third cT1 gastric cancer

BACKGROUND

The appropriate surgical procedure for patients with upper third early gastric cancer is controversial. We compared total gastrectomy (TG) with proximal gastrectomy (PG) in this patient population.

METHODS

A multicenter, non-randomized trial was conducted, with patients treated with PG or TG. We compared short- and long-term outcomes between these procedures.

RESULTS

Between 2009 and 2014, we enrolled 254 patients from 22 institutions; data from 252 were included in the analysis. These 252 patients were assigned to either the PG (n = 159) or TG (n = 93) group. Percentage of body weight loss (%BWL) at 1 year after surgery, i.e., the primary endpoint, in the PG group was significantly less than that of the TG group (- 12.8% versus - 16.9%; p = 0.0001). For short-term outcomes, operation time was significantly shorter for PG than TG (252 min versus 303 min; p < 0.0001), but there were no group-dependent differences in blood loss and postoperative complications. For long-term outcomes, incidence of reflux esophagitis in the PG group was significantly higher than that of the TG group (14.5% versus 5.4%; p = 0.02), while there were no differences in the incidence of anastomotic stenosis between the two (5.7% versus 5.4%; p = 0.92). Overall patient survival rates were similar between the two groups (3-year survival rates: 96% versus 92% in the PG and TG groups, respectively; p = 0.49).

CONCLUSIONS

Patients who underwent PG were better able to control weight loss without worsening the prognosis, relative to those in the TG group. Optimization of a reconstruction method to reduce reflux in PG patients will be important.

Intracellular Localization of Mycoplasma bovis in the Bronchiolar Epithelium of Experimentally Infected Calves

Lung tissues from calves infected experimentally with Mycoplasma bovis were examined by immunohistochemistry and electron microscopy. All inoculated calves had dark red areas of consolidation affecting both left and right lungs, which were characterized microscopically by subacute purulent bronchiolitis with hyperplasia of the surrounding lymphoid tissue. Immunohistochemically, M. bovis antigen was detected on the surface and inside the cytoplasm of bronchiolar epithelial cells in the pneumonic foci. The antigen was also found in the cytoplasm of phagocytes at the margin of bronchiolar exudates. Electron microscopically, numerous organisms were demonstrated in the immunohistochemically-positive sites. These findings suggest that M. bovis organisms adhere to the bronchiolar epithelium and at least some of them invade the epithelium.

Understanding the asymmetry between advancing and receding microscopic contact angles

By means of molecular dynamics simulation, the advancing and receding microscopic contact angles were analyzed for a shear flow of two mono-atomic fluids confined between parallel non-polar solid walls. We defined the microscopic dynamic contact angle based on the coarse-grained microscopic density distribution of the fluids (the instantaneous interface method [Willard and Chandler, J. Phys. Chem. B, 2010, 114, 1954-1958]) near the moving contact line. We have found that the asymmetric change of fluid density near the wall with respect to the moving contact line results in a different dependence between the advancing and receding contact angles on the contact line velocity in a system where the two fluids across the interface have unequal wettability to the solid wall. This difference between the advancing and receding contact angles leads to different flow resistance caused by the advancing and receding contact lines, which should have impact on the industrial applications of the fine fluid transportation with contact lines.

Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers

Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

[A Three-Year Survival Case of Extrahepatic Cholangiocarcinoma Treated with Palliative Bile Duct Resection and S-1 Monotherapy]

We report a 3-year survival case of cholangiocarcinoma treated with S-1 monotherapy despite positive margins after palliative bile duct resection. A 66 year-old man visited our hospital for jaundice. Because a smooth round defect was observed in the middle bile duct on ERCP, an impacted stone was suspected. Bile duct incision was performed, but the suspected stone was a tumor that was pathologically diagnosed as cholangiocarcinoma. Although pancreaticoduodenectomy was recommended, the patient decided to undergo palliative bile duct resection. Postoperative pathological examination showed moderately tubular adenocarcinoma with lymph node metastasis. The surgical margins of the hepatic side, duodenal side, and exfoliated surface were all positive. Subsequently, the patient chose to undergo S-1 monotherapy for maintaining his lifestyle. S-1 was orally administered at 100mg/day for 4 weeks, followed by 2 weeks of rest. He has continued S-1 monotherapy and survived for 3 years without evidence of recurrence.

Demonstration of the stabilization technique for nonplanar optical resonant cavities utilizing polarization

Based on our previously developed scheme to stabilize nonplanar optical resonant cavities utilizing polarization caused by a geometric phase in electromagnetic waves traveling along a twisted path, we report an application of the technique for a cavity installed in the Accelerator Test Facility, a 1.3-GeV electron beam accelerator at KEK, in which photons are generated by laser-Compton scattering. We successfully achieved a power enhancement of 1200 with 1.4% fluctuation, which means that the optical path length of the cavity has been controlled with a precision of 14 pm under an accelerator environment. In addition, polarization switching utilizing a geometric phase of the nonplanar cavity was demonstrated.

Characterization and genetic analyses of a carbazole-degrading gram-positive marine isolate, Janibacter sp. strain OC11

Strain OC11 was isolated from seawater sampled at the coast of Chiba, Japan, in artificial seawater medium with carbazole (CAR) as the sole carbon source. Its 16S ribosomal RNA gene sequence suggested that strain OC11 belongs to the genus Janibacter. The CAR-degradation genes (car genes) of strain OC11 were PCR amplified, using degenerate primers designed based on the car gene sequences of other CAR-degrading bacteria. Complete nucleotide sequences encoding six complete open reading frames were determined, and the first known ferredoxin reductase gene (carAd) was found from a CAR-degrading bacterium isolated from the marine environment. An experiment using a mutant strain suggested that the car genes of strain OC11 are functional in CAR degradation. Southern hybridization indicated that strain OC11 had one car gene cluster in vivo. RT-PCR revealed that transcription of carOC11 constitutes an operon.

Genes Involved in Aniline Degradation byDelftia acidovoransStrain 7N and Its Distribution in the Natural Environment

Aniline-degraders were isolated from activated sludge and environmental samples and classified into eight phylogenetic groups. Seven groups were classified into Gram-negative bacteria, such as Acidovorax sp., Acinetobacter sp., Delftia sp., Comamonas sp., and Pseudomonas sp., suggesting the possible dominance of Gram-negative aniline-degraders in the environment. Aniline degradative genes were cloned from D. acidovorans strain 7N, and the nucleotide sequence of the 8,039-bp fragment containing eight open reading frames was determined. Their deduced amino acid sequences showed homologies to glutamine synthetase (GS)-like protein, glutamine amidotransferase (GA)-like protein, large and small subunits of aniline dioxygenase, reductase, LysR-type regulator, small ferredoxin-like protein, and catechol 2,3-dioxygenase, suggesting a high similarity of this gene cluster to those in P. putida strain UCC22 and Acinetobacter sp. strain YAA. Polymerase chain reaction (PCR) and sequencing analyses of GS-like protein gene segments of other Gram-negative bacteria suggested that Gram-negative bacteria have aniline degradative gene that can be divided into two distinctive groups.

A Series of Crystal Structures of ameta-Cleavage Product Hydrolase fromPseudomonas fluorescensIP01 (CumD) Complexed with Various Cleavage Products

Meta-cleavage product hydrolase (MCP-hydrolase) is one of the key enzymes in the microbial degradation of aromatic compounds. MCP-hydrolase produces 2-hydroxypenta-2,4-dienoate and various organic acids, according to the C6 substituent of the substrate. Comprehensive analysis of the substrate specificity of the MCP-hydrolase from Pseudomonas fluorescens IP01 (CumD) was carried out by determining the kinetic parameters for nine substrates and crystal structures complexed with eight cleavage products. CumD preferred substrates with long non-branched C6 substituents, but did not effectively hydrolyze a substrate with a phenyl group. Superimposition of the complex structures indicated that benzoate was bound in a significantly different direction than other aliphatic cleavage products. The directions of the bound organic acids appeared to be related with the k(cat) values of the corresponding substrates. The Ile139 and Trp143 residues on helix alpha4 appeared to cause steric hindrance with the aromatic ring of the substrate, which hampers base-catalyzed attack by water.

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.

Clinical significance of plasma fibrinogen level as a predictive marker for postoperative recurrence of esophageal squamous cell carcinoma in patients receiving neoadjuvant treatment

Among multidisciplinary therapies developed for advanced esophageal cancer, neoadjuvant chemotherapy and chemoradiotherapy have been established as standard treatments. To deliver cautious follow up and intense treatment for high-risk patients, a simple and instructive biomarker for the postoperative recurrence needs to be identified. Fibrinogen, a common component of hemostasis, has been suggested to not only play an important role in cancer metastasis, but also correlate with tumor recurrence. We aim to clarify the validity of plasma fibrinogen as a marker for predicting the postoperative recurrence of esophageal squamous cell carcinoma patients who received neoadjuvant treatment. We reviewed 72 consecutive patients with esophageal squamous cell carcinoma who received neoadjuvant chemotherapy or chemoradiotherapy, followed by esophagectomy at the Keio University Hospital from 2001 to 2010. Of them, we retrospectively examined 68 patients who underwent plasma fibrinogen examination before and after neoadjuvant treatment and underwent transthoracic radical esophagectomy. We investigated patient characteristics, clinicopathological factors, neoadjuvant treatment effects, postoperative course, and plasma fibrinogen levels. We investigated pretreatment and preoperative (postneoadjuvant treatment) plasma fibrinogen levels, as well as changes in fibrinogen levels before and after neoadjuvant treatment. Patients with preoperative hyperfibrinogenemia (>350 mg/dL) and patients with increased plasma fibrinogen levels during neoadjuvant treatment showed significantly shorter postoperative disease-free survival (DFS) (P = 0.002 and P = 0.037, respectively). Moreover, we classified these patients into three classes on the basis of their preoperative fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment. Patients who had both high preoperative plasma fibrinogen and increased fibrinogen levels showed significantly shorter DFS than others. In contrast, patients who had normal preoperative plasma fibrinogen and decreased fibrinogen levels showed significantly longer DFS. Based on this fibrinogen classification, we could differentiate between significantly favorable and poor prognosis patients group. Overall, this classification (hazard ratio = 1.812, P = 0.013) and the response to neoadjuvant treatment (hazard ratio = 0.350, P = 0.007) were found to be significant determining factors for postoperative DFS. With the validity of preoperative plasma fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment, the plasma fibrinogen level was found to be a possible biomarker for postoperative recurrence in advanced esophageal cancer patients who received neoadjuvant treatment. Moreover, plasma fibrinogen classification could be a simple and valuable predictive marker for postoperative follow up.

Clinical utility of preoperative evaluation of bronchial arteries by three-dimensional computed tomographic angiography for esophageal cancer surgery

An identification of bronchial arteries (BAs) is critical in esophageal cancer surgery to avoid tracheobronchial ischemia and unexpected massive bleeding during surgical procedure particularly in thoracoscopic video-assisted esophagectomy. We describe the efficacy of three-dimensional computed tomographic angiography (3D-CTA) of BAs for preoperative evaluation in esophageal cancer surgery. Sixty-four patients with esophageal cancer who preoperatively underwent multidetector computed tomography examination were included in this study. We evaluated the number, origin, and intraoperative preservation rate of BAs, and we compared the number of thoracic paratracheal lymph nodes harvested between two groups comprising patients who either underwent preoperative 3D-CTA of BAs (3D-CTA group) or did not (non-3D-CTA group). The right and left BAs were preoperatively identified in 62 patients (97%) and 55 patients (86%), respectively, using 3D-CTA. In 34 patients (53%), the right BA originated as a common trunk with the right intercostal artery. In 48 patients (75%), the left BA originated from the descending aorta as a single or double branch. Some anomalies such as the right BA originated from the left subclavian artery were observed. In all patients, either the right or the left BA was preserved. The number of harvested lymph nodes in left side of paratrachea was significantly increased in 3D-CTA group, than those in non-3D-CTA group. 3D-CTA clearly revealed BA anatomy, contributing to BA preservation and safe and precise lymphadenectomy in esophageal cancer surgery. 3D-CTA of BAs is useful for preoperative evaluation in esophageal cancer surgery.

Tension of red blood cell membrane in simple shear flow

When a red blood cell (RBC) is subjected to an external flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a simple shear flow and the resulting elastic tensions on the membrane. The large deformation of the red blood cell is modelled by coupling a finite element method to solve the membrane mechanics and a boundary element method to solve the flows of the internal and external liquids. Depending on the capillary number Ca, ratio of the viscous to elastic forces, we observe three kinds of RBC motion: tumbling at low Ca, swinging at larger Ca, and breathing at the transitions. In the swinging regime, the region of the high principal tensions periodically oscillates, whereas that of the high isotropic tensions is almost unchanged. Due to the strain-hardening property of the membrane, the deformation is limited but the membrane tension increases monotonically with the capillary number. We have quantitatively compared our numerical results with former experimental results. It indicates that a membrane isotropic tension O(10{-6} N/m) is high enough for molecular release from RBCs and that the typical maximum membrane principal tension for haemolysis would be O(10{-4} N/m). These findings are useful to clarify not only the membrane rupture but also the mechanotransduction of RBCs.