Understanding a Core Pilin of the Type IVa Pili of Acidithiobacillus thiooxidans, PilV

( Araceli Hernández-sánchez ),( Edgar D. Páez-pérez ),( Elvia Alfaro-saldaña ),( Vanesa Olivares-illana ),( J. Viridiana García-meza ) 한국미생물생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.3

Pilins are protein subunits of pili. The pilins of type IV pili (T4P) in pathogenic bacteria are well characterized, but anything is known about the T4P proteins in acidophilic chemolithoautotrophic microorganisms such as the genus Acidithiobacillus. The interest in T4P of A. thiooxidans is because of their possible role in cell recruitment and bacterial aggregation on the surface of minerals during biooxidation of sulfide minerals. In this study we present a successful ad hoc methodology for the heterologous expression and purification of extracellular proteins such as the minor pilin PilV of the T4P of A. thiooxidans, a pilin exposed to extreme conditions of acidity and high oxidation-reduction potentials, and that interact with metal sulfides in an environment rich in dissolved minerals. Once obtained, the model structure of A. thiooxidans PilV revealed the core basic architecture of T4P pilins. Because of the acidophilic condition, we carried out in silico characterization of the protonation status of acidic and basic residues of PilV in order to calculate the ionization state at specific pH values and evaluated their pH stability. Further biophysical characterization was done using UV-visible and fluorescence spectroscopy and the results showed that PilV remains soluble and stable even after exposure to significant changes of pH. PilV has a unique amino acid composition that exhibits acid stability, with significant biotechnology implications such as biooxidation of sulfide minerals. The biophysics profiles of PilV open new paradigms about resilient proteins and stimulate the study of other pilins from extremophiles.

International comparison CCQM-K82: methane in air at ambient level (1800 to 2200) nmol/mol

Flores, Edgar,Viallon, Joë,le,Choteau, Tiphaine,Moussay, Philippe,I Wielgosz, Robert,Kang, Namgoo,Moon Kim, Byung,Zalewska, Ewelina,(A M H) van der Veen, Adriaan,Konopelko, Leonid,Wu, Hai,Han, Qia IOP 2015 Metrologia Vol.52 No.-

<P>The CCQM-K82 comparison was designed to evaluate the degrees of equivalence of NMI capabilities for methane in air primary reference mixtures in the range (1800 to 2200) nmol/mol. The balance gas for the standards was either scrubbed dry real air or synthetic air.</P> <P> CH<SUB>4</SUB> in air standards have been produced by a number of laboratories for many years, with more recent developments focused on standards at atmospheric measurement concentrations and aimed at obtaining agreement between independently produced standards. A comparison of the differences in primary gas standards for methane in air was previously performed in 2003 (CCQM-P41 Greenhouse gases. 1 and 2) with a standard deviation of results around the reference value of 30 nmol/mol and 10 nmol/mol for a more limited set of standards. This can be contrasted with the level of agreement required from field laboratories routinely measuring atmospheric methane levels, set by Data Quality Objectives (DQO) established by the World Meteorological Organization (WMO) to reflect the scientifically desirable level of compatibility for CH<SUB>4</SUB> measurements at the global scale, currently set at 2 nmol/mol (1 sigma).</P> <P> The measurements of this key comparison took place from May 2012 to June 2012.</P> <P> Eight laboratories took part in this comparison coordinated by the BIPM and NIST. Key comparison reference values were calculated based on Cavity Ring Down Spectroscopy Measurements performed at the BIPM, combined with participant's gravimetric values to identify a consistent set of standards. Regression analysis allowed predicted values for each standard to be calculated which acted as the KCRVs. In this comparison reported standard uncertainties by participants ranged from 0.50 nmol/mol to 2.4 nmol/mol and the uncertainties of individual KCRVs ranged from 0.68 nmol/mol to 0.71 nmol/mol.</P> <P> The standard deviation of the ensemble of standards about the KCRV value was 1.70 nmol/mol. This represents a greater than tenfold improvement in the level of compatibility of methane in air standards compared to that demonstrated in 2003. Further improvements in the compatibility of standards will require improved methods and uncertainties for the measurement of trace level methane in balance gases. </P> <P><B>Main text.</B> To reach the main text of this paper, click on <A HREF='http://www.bipm.org/utils/common/pdf/final_reports/QM/K82/CCQM-K82.pdf'>Final Report</A>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <A HREF='http://kcdb.bipm.org/'>kcdb.bipm.org/</A>.</P> <P>The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

CCQM-K120 (Carbon dioxide at background and urban level)

Flores, Edgar,Viallon, Joë,le,Choteau, Tiphaine,Moussay, Philippe,Idrees, Faraz,Wielgosz, Robert I,Lee, Jeongsoon,Zalewska, Ewelina,Nieuwenkamp, Gerard,Veen, Adriaan van der,Konopelko, L A,Kustiko BUREAU INTERNATIONAL DES POIDS ET MESURES 2019 METROLOGIA -BERLIN- Vol.56 No.-

<P></P> <P>CCQM-K120.a comparison involves preparing standards of carbon dioxide in air which are fit for purpose for the atmospheric monitoring community, with stringent requirements on matrix composition and measurement uncertainty of the CO<SUB>2</SUB> mole fraction. This represents an analytical challenge and is therefore considered as a Track C comparison. The comparison will underpin CMC claims for CO<SUB>2</SUB> in air for standards and calibrations services for the atmospheric monitoring community, matrix matched to real air, over the mole fraction range of 250 μmol/mol to 520 μmol/mol.</P> <P>CCQM-K120.b comparison tests core skills and competencies required in gravimetric preparation, analytical certification and purity analysis. It is considered as a Track A comparison. It will underpin CO<SUB>2</SUB> in air and nitrogen claims in a mole fraction range starting at the smallest participant's reported expanded uncertainty and ending at 500 mmol/mol. Participants successful in this comparison may use their result in the flexible scheme and underpin claims for all core mixtures</P> <P>This study has involved a comparison at the BIPM of a suite of 44 gas standards prepared by each of the participating laboratories. Fourteen laboratories took part in both comparisons (CCQM-K120.a, CCQM-K120.b) and just one solely in the CCQM-K120.b comparison.</P> <P>The standards were sent to the BIPM where the comparison measurements were performed. Two measurement methods were used to compare the standards, to ensure no measurement method dependant bias: GC-FID and FTIR spectroscopic analysis corrected for isotopic variation in the CO<SUB>2</SUB> gases, measured at the BIPM using absorption laser spectroscopy. Following the advice of the CCQM Gas Analysis Working Group, results from the FTIR method were used to calculate the key comparison reference values.</P> <P>KEY WORDS FOR SEARCH</P> <P>FTIR, CO2, GC-FID, Carbon dioxide at background level, Carbon dioxide at urban level, Delta Ray, CO2 gas standards</P> <P></P> <H2>Main text</H2> <P> To reach the main text of this paper, click on <A HREF='https://www.bipm.org/utils/common/pdf/final_reports/QM/K120/CCQM-K120.pdf'>Final Report</A>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <A HREF='http://kcdb.bipm.org/'>kcdb.bipm.org/</A>.</P> <P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Internal maxillary artery (IMax) – middle cerebral artery bypass in a patient with bilateral atherosclerotic carotid occlusion: A technical case report

Javier Degollado-García,Martin R. Casas-Martínez,Bill Roy Ferrufino Mejia,Juan C. Balcázar-Padrón,Héctor A. Rodríguez-Rubio,Edgar Nathal 대한뇌혈관외과학회 2024 Journal of Cerebrovascular and Endovascular Neuros Vol.26 No.1

Since the first description of the possible utilization of the internal maxillary artery for bypass surgery, there are some reports of its use in aneurysm cases; however, there is no information about the possible advantages of this type of bypass for cerebral ischemic disease.We present a 77-year-old man with a history of diabetes, hypertension, systemic atherosclerosis, and two acute myocardial infarctions with left hemiparesis. Imaging studies reported total occlusion of the right internal carotid artery and 75% occlusion on the left side, with an old opercular infarction and repeated transient ischemic attacks in the right middle cerebral artery territory despite medical treatment. After a consensus, we decided to perform a bypass from the internal maxillary artery to the M2 segment of the middle cerebral artery using a radial artery graft. After performing the proximal anastomosis, the calculated graft’s free flow was 216 ml/min. Subsequently, after completing the bypass, the patency was confirmed with fluorescein videoangiography and intraoperative Doppler. Postoperatively, imaging studies showed improvement in the perfusion values and the hemiparesis from 3/5 to 4+/5. The patient was discharged one week after the operation, with a modified Rankin scale of 1, without added deficits.The use of revascularization techniques in steno-occlusive disease indicates a select group of patients that may benefit from this procedure. In addition, internal maxillary artery bypass has provided a safe option for large areas of ischemia that cannot be supplied with a superficial temporal artery - middle cerebral artery bypass.

Growth performance, carcass traits, muscle fiber characteristics and skeletal muscle mRNA abundance in hair lambs supplemented with ferulic acid

( Edgar Fernando Peña-torres ),( Candelario Castillo-salas ),( Ismael Jiménez-estrada ),( Adriana Muhlia-almazán ),( Etna Aida Peña-ramos ),( Araceli Pinelli-saavedra ),( Leonel Avendaño-reyes ),( Cin 한국축산학회 2022 한국축산학회지 Vol.64 No.1

Ferulic acid (FA) is a phytochemical with various bioactive properties. It has recently been proposed that due to its phytogenic action it can be used as an alternative growth promoter additive to synthetic compounds. The objective of the present study was to evaluate the growth performance, carcass traits, fiber characterization and skeletal muscle gene expression on hair-lambs supplemented with two doses of FA. Thirty-two male lambs (n = 8 per treatment) were individually housed during a 32 d feeding trial to evaluate the effect of FA (300 and 600 mg d^-1) or zilpaterol hydrochloride (ZH; 6 mg d^-1) on growth performance, and then slaughtered to evaluate the effects on carcass traits, and muscle fibers morphometry from Longissimus thoracis (LT) and mRNA abundance of β2-adrenergic receptor (β₂-AR), MHC-I, MHC-IIX and IGF-I genes. FA increased final weight and average daily gain with respect to non-supplemented animals (p < 0.05). The ZH supplementation increased LT muscle area, with respect to FA doses and control (p < 0.05). Cross-sectional area (CSA) of oxidative fibers was larger with FA doses and ZH (p < 0.05). Feeding ZH increased mRNA abundance for β₂-AR compared to FA and control (p < 0.05), and expression of MHC-I was affected by FA doses and ZH (p < 0.05). Overall, FA supplementation of male hair lambs enhanced productive variables due to skeletal muscle hypertrophy caused by MHC-I up-regulation. Results suggest that FA has the potential like a growth promoter in lambs.

Optical scattering in glass ceramics

A. Edgar,G.V.M. Williams,J. Hamelin 한국물리학회 2006 Current Applied Physics Vol.6 No.3

We analyse measurements of the optical extinction coefficient for fluorozirconate glasses containing a volume fraction of 0.2 of barium chloride nano-particles. We find that the glass ceramics are about a factor of six more transparent than predicted by Rayleigh scattering theory, based on estimates of particle sizes from X-ray diffraction and electron microscopy measurements. A numerical simulation of scattering using the discrete-dipole approximation has been made in order to investigate whether this particular discrepancy, and the ‘‘ultra-transparency’’ observed in other glass ceramics in general, can be explained by particle proximity and interaction effects as has been proposed in the literature. The simulated scattering system behaves essentially as a collection of independent scatterers up to a volume fraction of at least 25%, and so these effects are not responsible for the high transparency in this system.

A Simple Metabolic Flux Balance Analysis of Biomass and Bioethanol Production in Saccharomyces cerevisiae Fed-batch Cultures

Iliana Barrera-Martinez,R. Axayácatl González-García,Edgar Salgado-Manjarrez,Juan S. Aranda-Barradas 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1

Production of Saccharomyces cerevisiae yeast for applications in the food industry or in bioethanol production still presents important techno-economic challenges as an industrial bioprocess. Mathematical modeling of cellular metabolism in biological production usually improves process yields, though for industrial applications,the model should be as simple as possible in order to sustain model usefulness and technical feasibility. A comparative analysis between a black box description and a simple metabolic network accounting for the main metabolic events involved in yeast growth and bioethanol production is proposed here. In both cases, a thorough analysis of reaction rates allowed for the ethanol concentrations produced in fed-batch yeast cultures, although our results showed more accurate estimations with the metabolic flux balance methodology. Moreover, an interpretation of the yeast physiological state in fed-batch cultures at different glucose feed concentrations was accomplished by means of a stoichiometric analysis linked to the simplified metabolic network. The results confirmed that increasing glucose uptake rates, controlled mainly by the glucose concentration in the input flow, produced an up-regulation in reductive catabolism, resulting in higher ethanol excretion. The biomass production relied mostly on oxidative catabolism,which is controlled by the glucose and oxygen uptake rates. Thus, ethanol or biomass production is strongly dependent on the physiological state of yeast in the culture, which can be inferred from a suitable metabolic flux balance approach.

Lithium borate glass ceramics as thermal neutron imaging plates

G.A. Appleby,C.M. Bartle,G.V.M. Williams,A. Edgar 한국물리학회 2006 Current Applied Physics Vol.6 No.3

A new glass ceramic composed of a lithium borate glass matrix containing Eu-doped BaCl2 crystals has been developed for thermalneutron radiography, and has been tested for sensitivity toc-radiation. It is shown to exhibit photostimulated luminescence (PSL) uponX- and c-irradiation. The PSL arises from orthorhombic BaCl2 nanocrystallites in the glass ceramics, which also contain a PSL-inactivephase of cubic BaCl2. The relative PSL eciency of the glass ceramics has a strong dependence on gamma energy, which correlates withrelative half-thickness. The eect of uoride doping in the glass ceramics has been found to substantially increase the PSL, which rangesfrom. 0.6% without uoride doping to. 8% with 0.2 F:Cl concentration, all relative to Fujilm’s commercial neutron imaging plateBAS-ND.

Spatial resolution of a glass-ceramic X-ray storage phosphor

A. Edgar,G.V.M. Williams,S. Schweizer,J.-M. Spaeth 한국물리학회 2006 Current Applied Physics Vol.6 No.3

The spatial resolution of a glass-ceramic X-ray storage phosphor imaging plate has been measured using a scanned and focussed laserbeam. The glass ceramic comprises orthorhombic phase barium chloride crystals containing europium ions embedded in a uorozirco-nate glass matrix. The modulation transfer function extends to signicantly higher frequencies than for a commercial imaging plate basedmercial plate. The modulation transfer function has a bimodal character which we ascribe to component responses from the focussedlaser beam volume and from the surrounding scattering halo. A limitation on performance of this particular glass ceramic is the occur-rence of bubbles and other defects which scatter the read-out light beam and reduce the uniformity of the response.

Calculation of All Possible Stoichiometric Coefficients and Theoretical Yields of Microbial Global Reactions

Rafael Eduardo Hernández-Guisao,Aranda-Barradas Juan Silvestre,Badillo-Corona Agustín,García-Peña Elvia Inés,Salgado-Manjarrez Edgar 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.5

Stoichiometric analysis is a crucial step in biochemical processes because it allows us to find the proportions in which the substrates and products react. A system of algebraic equation is obtained from an elemental balance of the participating substances and determined, overdetermined or underdetermined systems can result depending on the number of substances and elements. Underdetermined systems are the most common ones as there are, generally, more substances than elemental balances. However, such systems have been poorly studied and a straightforward way to establish the solution space has not yet been reported. In this work a novel approach for finding all the possible solutions to such underdetermined systems is reported for the first time. The solutions space is expressed as a set of vectors which are here referred as extreme stoichiometries. To illustrate the general applicability and some uses of the proposed approach, three different fermentation systems are analyzed: growth of Chlamydomonas reinhardtii, a mixed culture for hydrogen production, and the growth of Saccharomyces cerevisiae. It is shown how the full stoichiometric spaces can be calculated for heterotrophy, autotrophy, mixotrophy, growth of mixed cultures in mixed substrates and how the experimental results should be contained in such spaces, what permits a consistency analysis. With the proposed method, it is now possible to estimate the maximum yields for any given microbial growth reaction and to assess the congruence of experimental data, even when the system is underdetermined.