Activation of the planar cell polarity formin DAAM1 leads to inhibition of endothelial cell proliferation,migration, and angiogenesis

The Wnt/planar cell polarity (PCP) pathway regulates directed cell movement during development and was recently found to play a critical role in endothelial cell proliferation and angiogenesis [Zhang Y, et al. (2006) Chem Biol 13:1001–1009; Masckauchan TN, et al. (2006) Mol Biol Cell 17:5163–5172]. However, the mechanisms by which PCP signaling components regulate angiogenesis remain unknown. We report that expression of a constitutively active C-terminal domain of Dishevelled-associated activator of morphogenesis 1 (DAAM1) selectively inhibited endothelial cell proliferation. Moreover, this activated construct suppressed endothelial cell migration and the ability to form coordinated networks in vivo and in vitro. Although constitutively active DAAM1 (CDAAM1) induced both actin polymerization and microtubule (MT) stabilization, the stabilization of MTs alone was sufficient to inhibit endothelial cell growth selectively. Inhibition of actin polymerization alone by jasplakinolide treatment failed to reproduce the inhibitory effects of CDAAM1. These results indicate that DAAM1 regulates endothelial cell growth through MT stabilization in a cell type-selective manner and suggest that PCP signaling plays a pivotal role in angiogenesis by regulating MT stabilization.     

Update on paroxysmal nocturnal haemoglobinuria: on the long way to understand the principles of the disease

The understanding of the clinical manifestations in paroxysmal nocturnal haemoglobinuria (PNH) has made great progress. The main symptoms of this disease such as abdominal pain, renal failure or pulmonary hypertension and even the basis of the dramatic thrombophilia can be related to intravascular haemolysis and liberation of free haemoglobin resulting in NO depletion. In addition, there has been a recent great progress in elucidating the pathophysiology of clonal expansion within PNH bone marrow. In the majority of patients with haemolytic PNH, there are additional mutations within genes beyond PIG‐A and rather affecting growth and differentiation of clonal bone marrow cells. In contrast to the formerly proposed single mechanism hypotheses such as immune selection or intrinsic gain of clonal dominance, this appears to follow a pattern of a complex clonal hierarchy putatively integrating both earlier anticipated mechanisms. Treatment of PNH is mainly supportive. The only curative approach as allogeneic stem cell transplantation should only be applied to patients with complications such as secondary bone marrow aplasia or transformation into MDS or AML. Symptomatic haemolytic PNH will be treated with eculizumab, an inhibitor of the terminal complement cascade. Treatment with eculizumab can significantly prevent PNH‐related symptoms including the abnormal thrombophilia. Recently, it was demonstrated that in contrast to untreated historic PNH patients, meanwhile a normal life expectancy is observed in eculizumab‐treated patients. The recently approved vaccine against meningococci type B by the European Medical Agency (EMA) could probably further help to prevent meningococcal sepsis due to the induced complement deficiency by eculizumab.     

Effects of conditioned reward and nonreward cues on the heart rate response to alcohol intoxication in male social drinkers

BACKGROUND: An exaggerated heart rate (HR) increase following alcohol intoxication has been suggested to reflect sensitivity to alcohol-induced reward. The goal of this study is to verify whether pairing alcohol ingestion with conditioned reward and nonreward cues can influence HR responses to alcohol in previously identified individuals with a low and a high HR response. METHODS: Fifty-six male social drinkers participated in a 2-day study. On day 1, participants consumed 0.75 g/kg of body weight of pure ethanol. A median split of the alcohol-induced HR responses identified groups of low and high HR responders. On day 2, both groups participated while sober in a computer task where distinct auditory and visual cues were paired either with monetary reward or no monetary reward. Subsequently, participants were randomly assigned to an alcohol challenge, which occurred while they were exposed to either the conditioned cues of reward or to the nonreward cues. RESULTS: The physiological response to alcohol intoxication on day 2 was compared with alcohol-induced HR responses on day 1 (neutral alcohol challenge) for both low and high HR responders. Paired t-tests showed that high HR responders had significantly decreased alcohol-induced HR responses on day 2 in the nonreward condition when compared with day 1. No other relationships between cardiac responses to alcohol and cue conditions were obtained. CONCLUSIONS: The rewarding nature of alcohol can be altered by the context in which it is consumed in a subset of individuals who are sensitive to alcohol's stimulating properties.     

Congress presidential address to the 30th meeting of the JSHBPS: the second opening of Japan on the way to a bright future

The 30th meeting of the JSHBPS is the first domestic meeting of our society to have been organized completely in English. In that sense, we have established the theme of the 30th meeting of the JSHBPS as “The Second Opening of Japan on the Way to a Bright Future”. Last 30 years, several strategies have been undertaken to battle hepatobiliary (HPB) malignancies, such as aggressive operative procedures, operative planning using state‐of‐the‐art technologies, neoadjuvant therapy, conversion surgery for initially unresectable diseases, and immunomodulation. According to the rapid development of precision medicine, HBP surgeons should have a literacy for individualized therapy. Here, I review recent improvements in regard to HBP surgery. In addition, education for the next generations should be our highest priority. Collaboration with foreign researchers is the most effective tool to promote personal growth.     

The Numerical Analysis of the In-Plane Constraint Influence on the Behavior of the Crack Subjected to Cyclic Loading

The paper presents the influence of in-plane constraints defined by T-stress on the behavior of a crack subjected to cyclic loading. In the analysis, a modified boundary layer model approach was used in which the cohesive model was introduced. In the simulations, the constant maximum value of the stress intensity factor and four levels of T-stress were defined. The model was subjected to ten repeated stress cycles. Based on the results obtained, an analysis of the effect of the in-plane constraint on selected aspects of crack behavior was made. The strong influence of in-plane constraint applied in the model on the crack closure and the fatigue crack growth rate was proven. Since the in-plane constraint described the influence of geometry on the stress field surrounding the fatigue crack tip in real geometry, the results suggested that it is possible to create precise formulae connecting the level of the in-plane constraint with the effective stress intensity factor range and to incorporate the T-stress or Q-stress level in the Paris law.     

Impact of parvovirus H‐1 infection on the expression of genes related to the MAPK signaling pathway in gastric cancer cells

OBJECTIVE: To investigate the cell cytotoxicity induced by the antineoplastic parvovirus H‐1 in gastric carcinoma cells. METHODS: The cytotoxicity of the H‐1 virus in the gastric cancer cell strain HGC27 was measured by MTT test and FACS analysis. The mRNA expressions of genes related to the mitogen‐activated protein kinase (MAPK) signaling transduction pathway were measured by RT‐PCR in HGC27 cells infected by the H‐1 virus. RESULTS: HGC27 cells were sensitive to the cytotoxicity of the H‐1 virus, although the cell cycle distribution was not significantly changed. The RT‐PCR results showed that 48 h after H‐1 virus infection of HGC27 cells the expression of creb was increased and that of erk1, stat2, p38‐γ, mek2, B‐raf and mtk1 was remarkably decreased. However, the expression of each of jnk2, ets and erk2 was unchanged. CONCLUSIONS: The mechanism of the cytotoxic effect of parvovirus H‐1 in HGC27 cells might be interference with specific cellular signaling trans­duction pathways, which would induce cell death. A modified and reconstructed parvovirus H‐1 could be a very useful tool for antitumor biochemical therapy.     

Development of a New Sr-O Parameterization to Describe the Influence of SrO on Iron-Phosphate Glass Structural Properties Using Molecular Dynamics Simulations

Iron-phosphate glasses, due to their properties, have many potential applications. One of the most promising seems to be nuclear waste immobilization. Radioactive ⁹⁰Sr isotope is the main short-lived product of fission and, due to its high solubility, it can enter groundwater and pose a threat to the environment. On the other hand, Sr is an important element in hard tissue metabolic processes, and phosphate glasses containing Sr are considered bioactive. This study investigated the effect of SrO addition on a glass structure of nominal 30Fe₂O₃-70P₂O₅ chemical composition using classical molecular dynamics simulations. To describe the interaction between Sr-O ion pairs, new interatomic potential parameters of the Buckingham-type were developed and tested for crystalline compounds. The short-range structure of the simulated glasses is presented and is in agreement with previous experimental and theoretical studies. The simulations showed that an increase in SrO content in the glass led to phosphate network depolymerization. Analysis demonstrated that the non-network oxygen did not take part in the phosphate network depolymerization. Furthermore, strontium aggregation in the glass structure was observed to lead to the non-homogeneity of the glass network. It was demonstrated that Sr ions prefer to locate near to Fe(II), which may induce crystallization of strontium phosphates with divalent iron.     

Impact of an alpha helix and a cysteine–cysteine disulfide bond on the resistance of bacterial adhesion pili to stress

Escherichia coli express adhesion pili that mediate attachment to host cell surfaces and are exposed to body fluids in the urinary and gastrointestinal tracts. Pilin subunits are organized into helical polymers, with a tip adhesin for specific host binding. Pili can elastically unwind when exposed to fluid flow forces, reducing the adhesin load, thereby facilitating sustained attachment. Here we investigate biophysical and structural differences of pili commonly expressed on bacteria that inhabit the urinary and intestinal tracts. Optical tweezers measurements reveal that class 1a pili of uropathogenic E. coli (UPEC), as well as class 1b of enterotoxigenic E. coli (ETEC), undergo an additional conformational change beyond pilus unwinding, providing significantly more elasticity to their structure than ETEC class 5 pili. Examining structural and steered molecular dynamics simulation data, we find that this difference in class 1 pili subunit behavior originates from an α-helical motif that can unfold when exposed to force. A disulfide bond cross-linking β-strands in class 1 pili stabilizes subunits, allowing them to tolerate higher forces than class 5 pili that lack this covalent bond. We suggest that these extra contributions to pilus resiliency are relevant for the UPEC niche, since resident bacteria are exposed to stronger, more transient drag forces compared to those experienced by ETEC bacteria in the mucosa of the intestinal tract. Interestingly, class 1b ETEC pili include the same structural features seen in UPEC pili, while requiring lower unwinding forces that are more similar to those of class 5 ETEC pili.

Escherichia coli have a remarkable ability to adapt to the environment, allowing these bacteria to colonize varying niches in humans and animals either as commensals or pathogens (1). The urinary and gastrointestinal tracts are examples of environments where pathogenic E. coli are common causes of acute urinary tract infections and severe diarrhea, respectively. In these niches, fluid flow is a natural defense mechanism, limiting attachment of pathogenic bacteria to epithelial cell surfaces (2, 3). To facilitate attachment under fluid flow that applies drag forces to a bacterium, E. coli use attachment organelles called adhesion pili or fimbriae (4) that are micrometer-long helical rod structures (Fig. 1A). The helical rod structure can unwind (5), and significantly extend its original length under tensile force. This unwinding allows cell-associated bacteria to withstand drag forces from fluid flow, by decreasing the load on the receptor-bound adhesin (6, 7) that binds to host receptors (8). The unwinding of pili is dependent on critical mechanical features of the fibers. If the pili are compromised, the bacteria’s ability to attach and stay attached under drag force is reduced significantly (9, 10), and enterotoxigenic E. coli (ETEC) with no pili are unable to cause disease (11). Uropathogenic E. coli (UPEC) and ETEC pili mechanics and structure have been investigated for decades, yet we still lack a complete picture of their mechanical differences and how these differences relate to their genetics, structure, and environmental niche.Open in a separate windowFig. 1.(A) Scanning electron microscopy image of E. coli bacteria expressing adhesion pili. (B) Cartoon of a pilus showing subunits assembled into a helix-like rod stabilized by layer-to-layer interactions between subunits n and n ± 3, and a region of unwinding. (C) High-resolution structure of a P pilus with each pilin subunit colored individually. (D) A trimer (3mer) of pilin subunits during unwinding. (PapA PDB ID: 5FLU.)Pili that are assembled via the “chaperone–usher pathway” are all genetically similar. These pili are “class 1 adhesion pili,” and pili from this class are expressed on both UPEC and ETEC bacteria, comprising class 1a and class 1b, respectively (12). Conversely, ETEC adhesion pili from the ‘alternate chaperone–usher pathway’ do not share this genetic similarity, comprising class 5 pilins (13). Structurally, both pilus types are composed of immunoglobulin (Ig)-like pilin subunits attached via a β-strand complementation head to tail, forming helical fibers of approximately 1,000 pilins with similar quaternary structure (14, 15). The stability of the quaternary helical rod structure is achieved via layer-to-layer bonds formed between subunits, primarily between subunits n and n + 3 (Fig. 1B). High-resolution three-dimensional helical reconstruction models exist for UPEC class 1 type 1 and P pili (Fig. 1 C and D), whereas the only class 5 ETEC pilus that has been reconstructed at a resolution sufficient for atomic model building is CFA/I pili (10, 16, 17). These reconstructions show that P pili and type 1 pili have a larger buried surface area between subunits n and n + 3 than CFA/I pili (1,616 Ų and 1,453 Ų, respectively, vs. 1,087 Ų). The magnitude of the buried surface area correlates well with the force needed to unwind the fibers. That is, larger buried surface area requires a higher tensile force: The force needed to unwind type 1 and P pili is more than fourfold that of CFA/I pili, ≈30 and 28 pN vs. 7 pN (17, 18). Overall, the unwinding capabilities of pili are well understood, and good biophysical models explain the measured force–extension curves (19–22). However, current force–extension data indicate that there is a puzzling difference in the mechanics of pili that these models cannot explain, that could be related to pilin sequence differences. Class 1 pili show an additional conformational change that takes place at almost twice the pilus unwinding force (≈60 pN), which makes them more elastic and allows significantly longer extensions than those of previously studied class 5 pili (18, 23–25). Since the conformational change in class 1 pili takes place after unwinding of the quaternary structure, it must occur when a pilus is already in its linearized form (subunits in a head-to-tail order). That is, after unwinding the helical rod, there are changes in secondary or tertiary structures of individual pilin subunits. However, these changes have not been explored.It is well established that class 1 pilin subunits are proteins with high mechanical stability. Pilin stability originates from the Ig-like structure that is assembled of six β-strands forming a β-sandwich, and includes a conserved disulfide bond that works as a mechanical lock (26, 27). These physical attributes yield pilins that are characterized by very high thermodynamic and kinetic stability, free energies of over 70 kJ/mol, and a half-life of 10⁸ y at 25 °C (26, 28), as well as being robust under tensile force (27). In contrast, little is known regarding the physical attributes of class 5 pilin stability, except that there are striking similarities with class 1 pilins regarding their IgG protein fold and size (25). Thus, we raise the following question: What provides the mechanical differences observed between class 1 and class 5 adhesion pili, and are differences related to environmental niche?To solve the aforementioned research question, we compared the mechanical differences and structural properties of UPEC- and ETEC-associated pili. We measured their mechanical properties using optical tweezers (OT) force spectroscopy, and we interpreted the experimental force–extension results in the final region of pilus extension using structural models and steered molecular dynamics (sMD) simulations. We also looked closely at class 1 ETEC pili that have more genetic homology to UPEC pili as compared to class 5 ETEC, to examine the relation between genetics, pilus mechanics, and environmental niche.     

Evaluation of Bacterial Adhesion to the ZrO2 Atomic Layer Deposited on the Surface of Cobalt-Chromium Dental Alloy Produced by DMLS Method

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO₂) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface.     

环境膳食与生物地球化学疾病的流行及预防

微量元素在水土中的不均匀分布通过膳食习惯和特定生活方式,使得某些生物地球化学疾病在我国广大农村中出现。硒缺乏结合其他因素可能使克山病、大骨节病和某些类型的碘缺乏病在相同或不同地区流行,他们长期以来严重危害广大农村居民的生命和健康。改革开放以来,人民生活水平提高,随之而来的是硒和有关营养素摄入量的增加和环境的改善,不少地方病的发病率大幅度下降。根据人体硒需要量及安全摄入量范围研究结果,作者提出了有效预防此类地方病的原则;同时还强调了在低硒区继续采取统一补硒措施的必要性。     

Effect of Layer and Film Thickness and Temperature on the Mechanical Property of Micro- and Nano-Layered PC/PMMA Films Subjected to Thermal Aging

Multilayered polymer films with biomimicking, layered structures have unique microstructures and many potential applications. However, a major limitation of polymer films is the deterioration of mechanical properties in working environments. To facilitate the design and development of multilayered polymer films, the impact of thermal aging on the mechanical behavior of micro- and nano-layered polymer films has been investigated experimentally. The composition of the polymer films that have been studied is 50 vol% polycarbonate (PC) and 50 vol% poly(methyl methacrylate) (PMMA). The current study focuses on the effect of film and layer thickness and temperature on the mechanical properties of the materials subjected to thermal aging. To study the effect of film and layer thickness, films with the same thickness, but various layer thicknesses, and films with the same layer thickness, but various film thicknesses, were thermally aged at 100 °C in a constant temperature oven for up to six weeks. The results show that as the layer thickness decreases to 31 nm, the film has a higher stiffness and strength, and the trend of the mechanical properties is relatively stable over aging. The ductility of all of the films decreases with aging time. To study the effect of temperature, the films with 4,096 layers (31 nm thick for each layer) were aged at 100 °C, 115 °C and 125 °C for up to four weeks. While the 100 °C aging results in a slight increase of the stiffness and strength of the films, the higher aging temperature caused a decrease of the stiffness and strength of the films. The ductility decreases with the aging time for all of the temperatures. The films become more brittle for higher aging temperatures.     

传承开拓，任重道远：中华医学会糖尿病学分会成立20周年回顾

本文对中华医学会糖尿病学分会的筹备、组建、成立、发展、壮大进行了系统回顾。