319 research outputs found
Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale
We present a study of the HII regions in the galaxy NGC 6754 from a two
pointing mosaic comprising 197,637 individual spectra, using Integral Field
Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science
Verification program. The data cover the entire galaxy out to ~2 effective
radii (re ), sampling its morphological structures with unprecedented spatial
resolution for a wide-field IFU. A complete census of the H ii regions limited
by the atmospheric seeing conditions was derived, comprising 396 individual
ionized sources. This is one of the largest and most complete catalogue of H ii
regions with spectroscopic information in a single galaxy. We use this
catalogue to derive the radial abundance gradient in this SBb galaxy, finding a
negative gradient with a slope consistent with the characteristic value for
disk galaxies recently reported. The large number of H ii regions allow us to
estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong
constraints on the proposed mechanisms for metal mixing in disk galaxies, like
radial movements associated with bars and spiral arms, when comparing with
simulations. We found evidence for an azimuthal variation of the oxygen
abundance, that may be related with the radial migration. These results
illustrate the unique capabilities of MUSE for the study of the enrichment
mechanisms in Local Universe galaxies.Comment: 13 pages, 7 Figurs, accepted for publishing in A&
An integrated overview on the regulation of sperm metabolism (glycolysis-Krebs cycle-oxidative phosphorylation)
An overview of the sperm metabolism is presented; using the stallion as a model we review glycolysis, Krebs Cycle and oxidative phosphorylation, paying special attention to the interactions among them. In addition, metabolism implies a series of coordinated oxidation-reduction reactions and in the course of these reactions reactive oxygen species (ROS) and reactive oxoaldehydes are produced ; the electron transport chain (ETC) in the mitochondria is the main source of the anion superoxide and hydrogen peroxide, while glycolysis produces 2-oxoaldehydes such as methylglyoxal as byproducts; due to the adjacent carbonyl groups are strong electrophiles (steal electrons oxidizing other compounds). Sophisticated mechanisms exist to maintain redox homeostasis, because ROS under controlled production also have important regulatory functions in the spermatozoa. The interactions between metabolism and production of reactive oxygen species are essential for proper sperm function, and deregulation of these processes rapidly leads to sperm malfunction and finally death. Lastly, we briefly describe two techniques that will expand our knowledge on sperm metabolism in the coming decades, metabolic flow cytometry and the use of the âomicsâ technologies, proteomics and metabolomics, specifically the micro and nano proteomics/metabolomics. A better understanding of the metabolism of the spermatozoa will lead to big improvements in sperm technologies and the diagnosis and treatment of male factor infertility
Low glucose and high pyruvate reduce the production of 2-oxoaldehydes, improving mitochondrial efficiency, redox regulation, and stallion sperm function
Energy metabolism in spermatozoa is complex and involves the metabolism of carbohydrate fatty acids and amino acids. The ATP produced in the electron transport chain in the mitochondria appears to be crucial for both sperm motility and maintaining viability, whereas glycolytic enzymes in the flagella may contribute to ATP production to sustain motility and velocity. Stallion spermatozoa seemingly use diverse metabolic strategies, and in this regard, a study of the metabolic proteome showed that Gene Ontology terms and Reactome pathways related to pyruvate metabolism and the Krebs cycle were predominant. Following this, the hypothesis that low glucose concentrations can provide sufficient support for motility and velocity, and thus glucose concentration can be significantly reduced in the medium, was tested. Aliquots of stallion semen in four different media were stored for 48 h at 18°C; a commercial extender containing 67 mM glucose was used as a control. Stallion spermatozoa stored in media with low glucose (1 mM) and high pyruvate (10 mM) (LG-HP) sustained better motility and velocities than those stored in the commercial extender formulated with very high glucose (61.7 ± 1.2% in INRA 96 vs 76.2 ± 1.0% in LG-HP media after 48 h of incubation at 18°C; P < 0.0001). Moreover, mitochondrial activity was superior in LG-HP extenders (24.1 ± 1.8% in INRA 96 vs 51.1 ± 0.7% in LG-HP of spermatozoa with active mitochondria after 48 h of storage at 18°C; P < 0.0001). Low glucose concentrations may permit more efficient sperm metabolism and redox regulation when substrates for an efficient tricarboxylic acid cycle are provided. The improvement seen using low glucose extenders is due to reductions in the levels of glyoxal and methylglyoxal, 2-oxoaldehydes formed during glycolysis; these compounds are potent electrophiles able to react with proteins, lipids, and DNA, causing sperm damage
Nosocomial transmission of multidrug-resistant Mycobacterium tuberculosis in Spain.
Before 1990, outbreaks of multidrug-resistanttuberculosis (MDRTB) were uncommon (1); sincethen, more than 10 outbreaks have been reported,all in hospitals and prisons in the eastern UnitedStates (2-7). Persons traditionally considered atrisk for MDRTB (foreign-born TB patients andthose inadequately treated for TB) have not beenassociated with these outbreaks. Instead, the pres-ence of patients with active TB near immunocom-promised patients in HIV-dedicated wards has ledto MDRTB-infected HIV patients whose TB casesoften go unrecognized. The patients receive inade-quate treatment in facilities without effective pro-cedures for isolating acid-fast bacilli; thesecircumstances favor nosocomial transmission.Health officials in other geographic areas whereHIV and TB are major public health threats havebeen alerted to this emerging problem, and sur-veillance systems have been designed (8).Drs. Herrera, PeirĂł, Castell, and Godoy have received ascholarship from the Fondo de InvestigaciĂłn Sanitaria delInstituto de Salud Carlos III during their 2-year epidemiologictraining period in the Field Epidemiology Training Program(Programa de EpidemiologĂa Aplicada de Campo)
Role of Endocrine-Disrupting Chemicals in the Pathogenesis of Non-Alcoholic Fatty Liver Disease: A Comprehensive Review
Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required
Obtaining cloud top height from WRF model vertical profiles: application to the EUSO program
The objective of the Extreme Universe Space Observatory (EUSO) program is detection and measurement of high-energy particles that reach earth?s atmosphere from space. Clouds at mid and upper levels of the troposphere can interfere with such detection. Therefore, determining cloud top height with high accuracy is crucial to estimating the effect of clouds on these measurements.With this aim, we developed a method to extract that height using cloud temperature via vertical profiles predicted by the WRF model
Evaluation of testicular echotexture with Ecotext as a diagnostic method of testicular dysfunction in stallions
This study aimed to assess if Ecotext, a new software for evaluation of testicular echotexture, is a good method for diagnosis of stallions with testicular dysfunction (TD). Relationships between Ecotext parameters and sperm motility and production, testicular volume, and testicular blood flow were also studied. Ecotext provides a total of six echotexture parameters: Ecotext 1 (black pixels), 2 (white pixels) and 3 (grey pixels), and another 3 parameters related to hypoechogenic areas: Ecotext tubular density (ETD), Ecotext tubular diameter (ETd), and Ecotext tubular area (ETA). Stallions (n = 33) were assessed using proven diagnostic techniques (spermiogram, B-mode and Pulse Doppler ultrasound), and subsequent analysis with Ecotext. Animals were classified as âcontrol stallionsâ (n:21, acceptable semen quality), and âstallions with TDâ (n:12, poor semen quality (TM < 60%, PM < 45% and total nÂș of sperm with PM < 2000 Ă 106 spz), that were subdivided into âinduced TD groupâ (immunized, anti-GnRH vaccine) and âacquired TD groupâ. The acquired TD group showed differences in all Ecotext parameters in relation to controls (Ecotext 1:0.11 ± 0.17 vs 2.82 ± 2.52, Ecotext 2:1584.0 ± 575.8 vs 388 ± 368.2, Ecotext 3:134.2 ± 9.26; ETA: 2.14 ± 0.59 vs 5.40 ± 1.90; ETd: 65.66 ± 6.27 vs 86.93 ± 10.65 and ETD: 92.35 ± 11.24 vs 132.10 ± 16.35, p †0.001). Results suggest acquired TD stallions were suffering testicular degeneration with loss of architecture and function as all Ecotext parameters were altered in relation to controls. Induced TD horses only showed a reduction in ETD (116.2 ± 8.59 vs 132.10 ± 16.35, p †0.001), despite all sperm parameters being worse. These findings suggested immunized stallions probably only experience an acute loss of testicular functionality and parenchyma architecture is likely not affected since differences in Ecotext parameters with control stallions were not detected. ETD was the best parameter to identify animals with TD (AUC: 0.84, optimal cut-off value of 124.3 seminiferous tubules/cm2). Correlations were found between ETD and Doppler indices (PI: 0.60; RI: 0.47 p †0.001), total testicular volume (r: 0.48; p †0.05) and sperm motility (TM:0.51; and PM:0.54; p †0.001) and production (r:0.51; p †0.001). In summary, Ecotext could identify changes in testicular echotexture of stallions with TD. Results open the possibility for new research focused on establishing the relationship between Ecotext parameters and histomorphometry features in stallion testes
Physical and Antimicrobial Properties of Compression-Molded Cassava Starch-Chitosan Films for Meat Preservation
[EN] Cassava starch-chitosan films were obtained by melt bending and compression molding, using glycerol and polyethylene glycol as plasticizers. Both the starch/chitosan and the polymer/plasticizer ratios were varied in order to analyze their effect on the physical properties of the films. Additionally, the antimicrobial activity of 70:30 polymer:plasticizer films was tested in cold-stored pork meat slices as affected by chitosan content. All film components were thermally stable up to 200 A degrees C, which guaranteed their thermostability during film processing. Starch and chitosan had limited miscibility by melt blending, which resulted in heterogeneous film microstructure. Polyethylene glycol partially crystallized in the films, to a greater extent as the chitosan ratio increased, which limited its plasticizing effect. The films with the highest plasticizer ratio were more permeable to water vapor, less rigid, and less resistant to break. The variation in the chitosan content did not have a significant effect on water vapor permeability. As the chitosan proportion increased, the films became less stretchable, more rigid, and more resistant to break, with a more saturated yellowish color. The incorporation of the highest amount of chitosan in the films led to the reduction in coliforms and total aerobic counts of cold-stored pork meat slices, thus extending their shelf-life.The authors acknowledge the financial support provided by the Spanish Ministerio de Economia y Competividad (Projects AGL2013-42989-R and AGL2016-76699-R). Author Cristina Valencia-Sullca thanks the Peruvian Grant National Program (PRONABEC Grant).Valencia-Sullca, CE.; AtarĂ©s Huerta, LM.; Vargas, M.; Chiralt, A. (2018). Physical and Antimicrobial Properties of Compression-Molded Cassava Starch-Chitosan Films for Meat Preservation. Food and Bioprocess Technology. 11(7):1339-1349. https://doi.org/10.1007/s11947-018-2094-5S13391349117Alves, V. D., Mali, S., Beleia, A., & Grossmann, M. V. (2007). Effect of glycerol and amylose enrichment on cassava starch film properties. Journal of Food Engineering, 78(3), 941â946.ASTM (1995). Standard test methods for water vapour transmission of materials. In: Standards designations: E96-95. Annual book of ASTM standards (pp. 406-413). Philadelphia, PA: American Society for Testing and Materials.ASTM (1999). Standard test method for specular gloss. In: Designation (D523). Annual book of ASTM standards, Vol. 06.01. Philadelphia, PA: American Society for Testing and Materials.ASTM (2001). Standard test method for tensile properties of thin plastic sheeting. In: Standard D882 annual book of American standard testing methods. Philadelphia, PA: American Society for Testing and Materials.AtarĂ©s, L., Bonilla, J., & Chiralt, A. (2010). Characterization of sodium caseinate-based edible films incorporated with cinnamon or ginger essential oils. Journal of Food Engineering, 100(4), 678â687.Bonilla, J., AtarĂ©s, L., Vargas, M., & Chiralt, A. (2013). Properties of wheat starch film-forming dispersions and films as affected by chitosan addition. Journal of Food Engineering, 114(3), 303â312.Bonilla, J., Fortunati, E., AtarĂ©s, L., Chiralt, A., & Kenny, J. (2014). Physical, structural and antimicrobial properties of poly vinyl alcohol-chitosan biodegradable films. Food Hydrocolloids, 35, 463â470.Bourtoom, T., & Chinnan, M. S. (2008). Preparation and properties of rice starchâchitosan blend biodegradable film. LWT-Food Science and Technology, 41(9), 1633â1641.Cano, A., JimĂ©nez, A., ChĂĄfer, M., GonzĂĄlez-MartĂnez, C., & Chiralt, A. (2014). Effect of amylose: amylopectin ratio and rice bran addition on starch films properties. Carbohydrate Polymers, 111(0), 543â555.Carvalho, A. J. F. (2008). Starch: Major sources, properties and applications as thermoplastic materials. In M. N. Belgacem & A. Gandini (Eds.), Monomers, polymers and composites from renewable resources. Amsterdam: Elsevier.Chillo, S., Flores, S., Mastromatteo, M., Conte, A., Gerschenson, L., & Del Nobile, M. A. (2008). Influence of glycerol and chitosan on tapioca starch-based edible film properties. Journal of Food Engineering, 88(2), 159â168.Commission Regulation, 2005 (EC) No 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs. In Official Journal of the European Union pp 338/1â338/26.Da RĂłz, A., Carvalho, A., Gandini, A., & Curvelo, A. (2006). The effect of plasticizers on thermoplastic starch compositions obtained by melt processing. Carbohydrate Polymers, 63(3), 417â424.Dang, K., & Yoksan, R. (2015). Development of thermoplastic starch blown film by incorporating plasticized chitosan. Carbohydrate Polymers, 115, 575â581.Dou, B., Dupont, V., Williams, P. T., Chen, H., & Ding, Y. (2009). Thermogravimetric kinetics of crude glycerol. Bioresource Technology, 100(9), 2613â2620.Fang, J., Fawler, P., Eserig, C., GonzĂĄlez, R., Costa, J., & Chamudis, L. (2005). Development of biodegradable laminate films derived from naturally occurring carbohydrate polymers. Carbohydrate Polymers, 60(1), 39â42.Hutchings, J. B. (1999). Food color and appearance (2nd ed.). Gaithersburg, Maryland, USA: Aspen Publishers, Inc..JimĂ©nez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2012a). Edible and biodegradable starch films: A review. Food Bioprocessing Technology, 5(6), 2058â2076.JimĂ©nez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2012b). Effect of re-crystallization on tensile, optical and water vapour barrier properties of corn starch films containing fatty acids. Food Hydrocolloids, 26(1), 302â310.LĂłpez, O., Garcia, A., Villar, M., Gentili, A., Rodriguez, M., & Albertengo, L. (2014). Thermo-compression of biodegradable thermoplastic corn starch films containing chitin and chitosan. LWT-Food Science and Technology, 57(106), 106â1515.Mali, S., Grossmann, M. V. E., GarcĂa, M. A., Martino, M. N., & Zaritsky, N. E. (2006). Effects of controlled storage on thermal, mechanical and barrier properties of plasticized films from different starch sources. Journal of Food Engineering, 75(4), 453â460.Mendes, J. F., Paschoalin, R. T., Carmona, V. B., Sena Neto, A. R. A., Marques, C. P., Marconcini, J. M., Mattoso, L. H. C., Medeiros, E. S., & Oliveira, J. E. (2016). Biodegradable polymer blends based on corn starch and thermoplastic chitosan processed by extrusion. Carbohydrate Polymers, 137, 452â458.Ortega-Toro, R., JimĂ©nez, A., Talens, P., & Chiralt, A. (2014). Properties of starchâhydroxypropyl methylcellulose based films obtained by compression molding. Carbohydrate Polymers, 109, 155â165.Ortega-Toro, R., Morey, I., Talens, P., & Chiralt, A. (2015). Active bilayer films of thermoplastic starch and polycaprolactone obtained by compression molding. Carbohydrate Polymers, 127, 282â290.Pelissari, F., Grossmann, M., Yamashita, F., & Pineda, E. (2009). Antimicrobial, mechanical and barrier properties of cassava starch-chitosan films incorporated with oregano essential oil. Journal of Agricultural and Food Chemistry, 57(16), 7499â7504.Pelissari, F. M., Yamashita, F., GarcĂa, M. A., Martino, M. N., Zaritzky, N. E., & Grossmann, M. V. E. (2012). Constrained mixture design applied to the development of cassava starch-chitosan blown films. Journal of Food Engineering, 108(2), 262â267.Song, R., Xue, R., He, L. H., Liu, Y., & Xiao, Q. L. (2008). The structure and properties of chitosan/polyethylene glycol/silica ternary hybrid organic-inorganic films. Chinese Journal of Polymer Science, 26(05), 621â630.v.Su, J. F., Huang, Z., Yuan, X. Y., Wang, X. Y., & Lim, M. (2010). Structure and properties of carboxymethyl cellulose/soy protein isolate blend edible films crosslinked by Maillard reactions. Carbohydrate Polymers, 79(1), 145â153.Thunwall, M., Boldizar, A., & Rigdahl, M. (2006). Compression molding and tensile properties of thermoplastic potato starch materials. Biomacromolecules, 7(3), 981â986.TomĂ©, L., Fernandes, S., Sadocco, P., Causio, J., Silvertre, A., Neto, P., & Freire, C. (2012). Antibacterial thermoplastic starch- chitosan based materials prepared by melt-mixing. BioResources, 7(3), 3398â3409.Villalobos, R., Chanona, J., HernĂĄndez, P., GutiĂ©rrez, G., & Chiralt, A. (2005). Gloss and transparency of hydroxypropyl methylcellulose films containing surfactants as affected by their microstructure. Food Hydrocolloids, 19(1), 53â61.Xu, Y. X., Kim, K. M., Hanna, M. A., & Nag, D. (2005). Chitosanâstarch composite film: Preparation and characterization. Industrial Crops and Products, 21(2), 185â192.Yang, L., & Paulson, A. T. (2000). Mechanical and water vapour barrier properties of edible gellan. Food Research International, 33(7), 563â570
- âŠ