Total Syntheses and Chemical Biology Studies of Hymeglusin and Fusarilactone A,Novel Circumventors of β-Lactam Drug Resistance in Methicillin-Resistant Staphylococcus aureus

Hymeglusin, a previously known eukaryotic hydroxymethylglutaryl-CoA (HMG−CoA) synthase inhibitor, was identified as circumventing the β-lactam drug resistance in methicillin-resistant Staphylococcus aureus (MRSA). We describe the concise total syntheses of a series of natural products, which enabled determination of the absolute configuration of fusarilactone A and provided structure-activity relationship information. Based on previous reports, we speculated that the target protein of this circumventing effect may be MRSA bacterial HMG−CoA synthase (mvaS). We found that this enzyme was dose-dependently inhibited by hymeglusin. Furthermore, overexpression of the MRSA mvaS gene and site-directed mutagenesis studies suggested its binding site and the mechanism of action.     

Cooperative control through objective achievement

Cooperative control is a key issue for multirobot systems in many practical applications. In this paper, we address the problem of coordinating a set of mobile robots in the RoboCup soccer middle-size league. We show how the coordination problem that we face can be cast as a specific coalition formation problem, and we propose a distributed algorithm to efficiently solve it. Our approach is based on the distributed computation of a measure of satisfaction (called Agent Satisfaction) that each agent computes for each task. We detail how each agent computes the Agent Satisfaction by acquiring sensor perceptions through an omnidirectional vision system, extracting aggregated information from the acquired perception, and integrating such information with that communicated by the teammates. We empirically validate our approach in a simulated scenario and within RoboCup competitions. The experiments in the simulated scenario allow us to analyse the behaviour of the algorithm in different situations, while the use of the algorithm in real competitions validates the applicability of our approach to robotic platforms involved in a dynamic and complex scenario.     

Surface and aqueous properties of anionic gemini surfactants having dialkyl amide,carboxyl, and carboxylate groups

A systematic study of the equilibrium surface properties (in water and in the presence of 10⁻² M NaCl) of a novel series of anionic gemini surfactants, (CH₂)₂[N(COC_nH_2n+1)CH(COOH)CH₂COOH]·2NaOH (GA), where (n+1)=8, 10, 12, 14, and 16, was investigated. The responses of humans to closed patch tests with (CH₂)₂[N(COC₁₁H₂₃)CH(COOH)−CH₂COOH]₂·2NaOH (GA-12) were also investigated. Premicellar self-aggregation (both in water and 10⁻² M NaCl) occurred when the N-acyl group contained more than 14 carbon atoms, since the critical micelle concentration (CMC) values decreased and the pC₂₀ values increased as (n+1) increased for (n+1) ≤14; the CMC values increased and the pC ₂₀ values decreased as (n+1) increased for (n+1)>14, both in water and in 10⁻² M NaCl. The absence of a break in the specific conductance-surfactant molar concentration plots for the GA homologs indicates protonation of the carboxylate group and strong Na⁺ release during micellization. This is a structural characteristic of the anionic geminis having N-dialkylamide and carboxylate groups in a molecule. The skin irritation potential of GA-12 is lower than that of the corresponding “monomer”, C₁₁H₂₃CON(CH₃)CH(COOH)CH₂(COOH)·NaOH, and the analog, C₁₁H₂₃CON(CH₃)CH₂COONa·H₂O.     

Two dimensional control of electron beam induced orientation selective epitaxial growth of (100) and (110)CeO2 regions on Si(100) substrates

Orientation selective epitaxy (OSE) of CeO₂(100) and CeO₂(110) layers on Si(100) substrates is studied using reactive magnetron sputtering. The former grows in an area simultaneously irradiated by electron beams during the growth process, whereas the latter grows in the area without electron irradiation. In order to control the electron beam irradiation area, we apply an absorbed electron imaging system. Analyses are made on the sample current profile along Si substrate surfaces and the current components of positive ions and secondary electrons. The spatially controlled OSE growth of the (100) and (110) oriented epitaxial regions is attained and crystallographic orientation distribution within the sample surface was analyzed.     

Sorption and diffusion of water vapor in poly(ethylene terephthalate) film

The sorption and diffusion of water vapor in poly(ethylene terephthalate) (PET) film were measured by applying a thermogravimetric analyzer (TG‐DTA), which customarily has been used to detect the weight loss of a sample with the increase of temperature under a given atmosphere. In this case, we detected the weight gain of PET film by sorption of water vapor under a given humidity at a constant temperature. Sorption‐rate curves were successfully obtained in spite of the low solubility of PET film and the presence of Fickian‐type curves. The solubility was better described according to the dual‐mode sorption model. The diffusion coefficients were determined in their initial slopes by the short‐time method. We found that the diffusion coefficient depended on vapor pressure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 67–74, 2000     

Characterization of monomeric and homodimeric forms of osteoclastogenesis inhibitory factor

PURPOSE: The purpose of this study was to characterize structural changes in the pulmonary vasculature in congenital diaphragmatic hernia (CDH) complicated by persistent pulmonary hypertension (PPH) with particular emphasis on adventitial thickness. METHODS: Victorian blue Van Gieson (VVG) staining and immunostaining with antialpha smooth muscle actin (ASMA) were performed on lung tissues obtained at autopsy from 23 patients with CDH complicated by PPH and 11 age-matched control tissues of sudden infant death syndrome patients (SIDS). The degree of medial and adventitial thickening was measured in pulmonary arteries with an external diameter (ED) of less than 75 microm, 75 to 100 microm, 100 to 150 microm, 150 to 250 microm, 250 to 500 microm, and greater than 500 microm by IPS-4.01 image analyzer and compared statistically. The degree of medial thickening and adventitial thickening was also measured in pulmonary veins with an ED of less than 100 microm, 100 to 200 microm, and greater than 200 microm. To determine whether the characteristic structural changes were size related, each was related to ED. The area of adventitia and media of the pulmonary arteries and veins was measured using image analyzer. RESULTS: There was a significant increase in medial and adventitial thickness in arteries of all sizes in CDH patients compared with controls (P < .01). The degree of adventitial area was significantly increased for arteries of all sizes (P < .01) and the degree of medial area was significantly increased only for arteries less than 100 microm size (P < .05) in CDH patients compared with controls. Calculation of the areas of the various components in the wall of each artery showed that for small arteries (<100 microm ED), the area of the lumen was smaller, and the areas of the media and adventitia were larger in CDH patients compared with controls (P < .01). There was a significant increase in adventitial thickness and area in veins of all sizes in CDH patients compared with controls (P < .01). The adventitial thickness of pulmonary veins were ED of less than 100 microm: CDH, 13.5 microm +/- 3.5; control, 9.21 microm +/- 2.0; ED 100 to 200 microm: CDH, 21.3 microm +/- 7.5; control, 13.0 microm +/- 4.8; ED greater than 200 microm: CDH, 34.4 microm +/- 12.5; control, 22.3 microm +/- 4.2. CONCLUSIONS: The present study provides the first quantitative demonstration of structural alterations in pulmonary veins in addition to pulmonary arteries in CDH complicated by PPH. The structural remodeling of the pulmonary vein is perhaps as a result of an increase in transvascular pressure in PPH.     

Use of a microcomputer with a gas permeation apparatus

Hardware and software for collecting and storing the data of gas permeation in polymer membranes from the vacuum detector and various sensors have been developed for the GP-IB microcomputer online system. The system uses BASIC language programs. In comparison to manual inputs and calculations, the programs allow reductions in the time required for data treatment and in the standard deviation for a determination and, moreover, an improvement in the reproducibility of the results.     

Irradiation performance of fast reactor MOX fuel pins with ferritic/martensitic cladding irradiated to high burnups

The ACO-3 irradiation test, which attained extremely high burnups of about 232 GWd/t and resisted a high neutron fluence (E > 0.1 MeV) of about 39 × 10²⁶ n/m² as one of the lead tests of the Core Demonstration Experiment in the Fast Flux Test Facility, demonstrated that the fuel pin cladding made of ferritic/martensitic HT-9 alloy had superior void swelling resistance. The measured diameter profiles of the irradiated ACO-3 fuel pins showed axially extensive incremental strain in the MOX fuel column region and localized incremental strain near the interfaces between the MOX fuel and upper blanket columns. These incremental strains were as low as 1.5% despite the extremely high level of the fast neutron fluence. Evaluation of the pin diametral strain indicated that the incremental strain in the MOX fuel column region was substantially due to cladding void swelling and irradiation creep caused by internal fission gas pressure, while the localized strain near the MOX fuel/upper blanket interface was likely the result of the pellet/cladding mechanical interaction (PCMI) caused by cesium/fuel reactions. The evaluation also suggested that the PCMI was effectively mitigated by a large gap size between the cladding and blanket column.