Plomo metálico en yacimientos de la I Edad del Hierro en la Provincia de Castellón: Explotación de recursos mineros y circulación del metal

Las investigaciones que estamos realizando en yacimientos de la I Edad del Hierro en la provincia de Castellón nos han permitido estudiar algunos de los primeros objetos de plomo caracterizando su composición mediante ED-XRFy ICP-MS. También se ha realizado un trabajo de localización de minas de plomo en la provincia, analizando las muestras recogidas en ellas para determinar su potencial uso para obtener plomo metálico o para extracción de plata. Finalmente tanto del material arqueológico como del geológico se han realizado análisis de isótopos de plomo con técnicas de alta precisión (TIMS o MC-ICP-MS) necesarias para conseguir una información comparable y minimizar los márgenes de error y de interpretación en la asignación a campos isotópicos de base geológica. Con estos análisis se pretende confirmar o rechazar el uso de los recursos provinciales de plomo durante este periodo histórico.HAR2010-21105-C02-02Peer reviewe

Corneal relaxation time estimation as a function of tear oxygen tension in human cornea during contact lens wear

[EN] The purpose is to estimate the oxygen diffusion coefficient and the relaxation time of the cornea with respect to the oxygen tension at the cornea-tears interface. Both findings are discussed. From the experimental data provided by Bonanno et al., the oxygen tension measurements in vivo for human cornea-tears-contact lens (CL), the relaxation time of the cornea, and their oxygen diffusion coefficient were obtained by numerical calculation using the Monod-kinetic model. Our results, considering the relaxation time of the cornea, observe a different behavior. At the time less than 8 s, the oxygen diffusivity process is upper-diffusive, and for the relaxation time greater than 8 s, the oxygen diffusivity process is lower-diffusive. Both cases depend on the partial pressure of oxygen at the entrance of the cornea. The oxygen tension distribution in the cornea-tears interface is separated into two different zones: one for conventional hydrogels, which is located between 6 and 75 mmHg, with a relaxation time included between 8 and 19 s, and the other zone for silicone hydrogel CLs, which is located at high oxygen tension, between 95 and 140 mmHg, with a relaxation time in the interval of 1.5-8 s. It is found that in each zone, the diffusion coefficient varies linearly with the oxygen concentration, presenting a discontinuity in the transition of 8 s. This could be interpreted as an aerobic-to-anaerobic transition. We attribute this behavior to the coupling formalism between oxygen diffusion and biochemical reactions to produce adenosine triphosphate.Contract grant sponsor: Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México; contract grant number: UNAM-DGAPA-PAPIIT projects IG 100618 and IN-114818 Contract grant sponsor: Secretaría de Estado de Investigación, Desarrollo e Innovación; contract grant number: ENE/2015-69203-RDel Castillo, LF.; Ramírez-Calderón, JG.; Del Castillo, RM.; Aguilella-Arzo, M.; Compañ Moreno, V. (2020). Corneal relaxation time estimation as a function of tear oxygen tension in human cornea during contact lens wear. Journal of Biomedical Materials Research Part B Applied Biomaterials. 108(1):14-21. https://doi.org/10.1002/jbm.b.34360S14211081Freeman, R. D. (1972). Oxygen consumption by the component layers of the cornea. The Journal of Physiology, 225(1), 15-32. doi:10.1113/jphysiol.1972.sp009927CHALMERS, R. L., McNALLY, J. J., SCHEIN, O. D., KATZ, J., TIELSCH, J. M., ALFONSO, E., … SHOVLIN, J. (2007). Risk Factors for Corneal Infiltrates with Continuous Wear of Contact Lenses. Optometry and Vision Science, 84(7), 573-579. doi:10.1097/opx.0b013e3180dc9a12Schein, O. D., McNally, J. J., Katz, J., Chalmers, R. L., Tielsch, J. M., Alfonso, E., … Shovlin, J. (2005). The Incidence of Microbial Keratitis among Wearers of a 30-Day Silicone Hydrogel Extended-Wear Contact Lens. Ophthalmology, 112(12), 2172-2179. doi:10.1016/j.ophtha.2005.09.014Sweeney, D. F. (2003). Clinical Signs of Hypoxia with High-Dk Soft Lens Extended Wear: Is the Cornea Convinced? Eye & Contact Lens: Science & Clinical Practice, S22-S25. doi:10.1097/00140068-200301001-00007HARVITT, D. M., & BONANNO, J. A. (1999). Re-Evaluation of the Oxygen Diffusion Model for Predicting Minimum Contact Lens Dk/t Values Needed to Avoid Corneal Anoxia. Optometry and Vision Science, 76(10), 712-719. doi:10.1097/00006324-199910000-00023Polse, K. A., & Mandell, R. B. (1970). Critical Oxygen Tension at the Corneal Surface. Archives of Ophthalmology, 84(4), 505-508. doi:10.1001/archopht.1970.00990040507021Giasson, C., & Bonanno, J. A. (1995). Acidification of rabbit corneal endothelium during contact lens wearin vitro. Current Eye Research, 14(4), 311-318. doi:10.3109/02713689509033531Riley, M. V. (1969). Glucose and oxygen utilization by the rabbit cornea. Experimental Eye Research, 8(2), 193-200. doi:10.1016/s0014-4835(69)80031-xFrahm, B., Lane, P., M�rkl, H., & P�rtner, R. (2003). Improvement of a mammalian cell culture process by adaptive, model-based dialysis fed-batch cultivation and suppression of apoptosis. Bioprocess and Biosystems Engineering, 26(1), 1-10. doi:10.1007/s00449-003-0335-zCompañ, V., Aguilella-Arzo, M., Del Castillo, L. F., Hernández, S. I., & Gonzalez-Meijome, J. M. (2016). Analysis of the application of the generalized monod kinetics model to describe the human corneal oxygen-consumption rate during soft contact lens wear. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 105(8), 2269-2281. doi:10.1002/jbm.b.33764Bonanno, J. A., Clark, C., Pruitt, J., & Alvord, L. (2009). Tear Oxygen Under Hydrogel and Silicone Hydrogel Contact Lenses in Humans. Optometry and Vision Science, 86(8), E936-E942. doi:10.1097/opx.0b013e3181b2f582Chhabra, M., Prausnitz, J. M., & Radke, C. J. (2008). Diffusion and Monod kinetics to determine in vivo human corneal oxygen-consumption rate during soft contact-lens wear. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 90B(1), 202-209. doi:10.1002/jbm.b.31274Chhabra, M., Prausnitz, J. M., & Radke, C. J. (2009). Modeling Corneal Metabolism and Oxygen Transport During Contact Lens Wear. Optometry and Vision Science, 86(5), 454-466. doi:10.1097/opx.0b013e31819f9e70Larrea, X., & Bu¨chler, P. (2009). A Transient Diffusion Model of the Cornea for the Assessment of Oxygen Diffusivity and Consumption. Investigative Opthalmology & Visual Science, 50(3), 1076. doi:10.1167/iovs.08-2479Alvord, L. A., Hall, W. J., Keyes, L. D., Morgan, C. F., & Winterton, L. C. (2007). Corneal Oxygen Distribution With Contact Lens Wear. Cornea, 26(6), 654-664. doi:10.1097/ico.0b013e31804f5a22Del Castillo, L. F., da Silva, A. R. F., Hernández, S. I., Aguilella, M., Andrio, A., Mollá, S., & Compañ, V. (2015). Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear. Journal of Optometry, 8(1), 12-18. doi:10.1016/j.optom.2014.06.002Chandel, N. S., Budinger, G. R. S., Choe, S. H., & Schumacker, P. T. (1997). Cellular Respiration during Hypoxia. Journal of Biological Chemistry, 272(30), 18808-18816. doi:10.1074/jbc.272.30.18808Leung, B. K., Bonanno, J. A., & Radke, C. J. (2011). Oxygen-deficient metabolism and corneal edema. Progress in Retinal and Eye Research, 30(6), 471-492. doi:10.1016/j.preteyeres.2011.07.001Chhabra, M., Prausnitz, J. M., & Radke, C. J. (2008). Polarographic Method for Measuring Oxygen Diffusivity and Solubility in Water-Saturated Polymer Films:  Application to Hypertransmissible Soft Contact Lenses. Industrial & Engineering Chemistry Research, 47(10), 3540-3550. doi:10.1021/ie071071aCompañ, V., Andrio, A., López-Alemany, A., Riande, E., & Refojo, M. F. (2002). Oxygen permeability of hydrogel contact lenses with organosilicon moieties. Biomaterials, 23(13), 2767-2772. doi:10.1016/s0142-9612(02)00012-1Gonzalez-Meijome, J. M., Compañ-Moreno, V., & Riande, E. (2008). Determination of Oxygen Permeability in Soft Contact Lenses Using a Polarographic Method:  Estimation of Relevant Physiological Parameters. Industrial & Engineering Chemistry Research, 47(10), 3619-3629. doi:10.1021/ie071403bCompa�, V., L�pez, M. L., Andrio, A., L�pez-Alemany, A., & Refojo, M. F. (1999). Determination of the oxygen transmissibility and permeability of hydrogel contact lenses. Journal of Applied Polymer Science, 72(3), 321-327. doi:10.1002/(sici)1097-4628(19990418)72:33.0.co;2-lGavara, R., & Compañ, V. (2016). Oxygen, water, and sodium chloride transport in soft contact lenses materials. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 105(8), 2218-2231. doi:10.1002/jbm.b.33762Compañ, V., Tiemblo, P., García, F., García, J. M., Guzmán, J., & Riande, E. (2005). A potentiostatic study of oxygen transport through poly(2-ethoxyethyl methacrylate-co-2,3-dihydroxypropylmethacrylate) hydrogel membranes. Biomaterials, 26(18), 3783-3791. doi:10.1016/j.biomaterials.2004.09.061Wang, J., Fonn, D., Simpson, T. L., & Jones, L. (2003). Precorneal and Pre- and Postlens Tear Film Thickness Measured Indirectly with Optical Coherence Tomography. Investigative Opthalmology & Visual Science, 44(6), 2524. doi:10.1167/iovs.02-0731Nichols, J. J., & King-Smith, P. E. (2003). Thickness of the Pre- and Post–Contact Lens Tear Film Measured In Vivo by Interferometry. Investigative Opthalmology & Visual Science, 44(1), 68. doi:10.1167/iovs.02-0377Compañ, V., Aguilella-Arzo, M., Edrington, T. B., & Weissman, B. A. (2016). Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear. Optometry and Vision Science, 93(11), 1339-1348. doi:10.1097/opx.0000000000000988Compañ, V., Aguilella-Arzo, M., & Weissman, B. A. (2017). Corneal Equilibrium Flux as a Function of Corneal Surface Oxygen Tension. Optometry and Vision Science, 94(6), 672-679. doi:10.1097/opx.0000000000001083Papas, E. B., & Sweeney, D. F. (2016). Interpreting the corneal response to oxygen: Is there a basis for re-evaluating data from gas-goggle studies? Experimental Eye Research, 151, 222-226. doi:10.1016/j.exer.2016.08.019Alentiev, A. Y., Shantarovich, V. P., Merkel, T. C., Bondar, V. I., Freeman, B. D., & Yampolskii, Y. P. (2002). Gas and Vapor Sorption, Permeation, and Diffusion in Glassy Amorphous Teflon AF1600. Macromolecules, 35(25), 9513-9522. doi:10.1021/ma020494fLin, H., & Freeman, B. D. (2005). Gas and Vapor Solubility in Cross-Linked Poly(ethylene Glycol Diacrylate). Macromolecules, 38(20), 8394-8407. doi:10.1021/ma051218eKoros, W. J., Paul, D. R., & Rocha, A. A. (1976). Carbon dioxide sorption and transport in polycarbonate. Journal of Polymer Science: Polymer Physics Edition, 14(4), 687-702. doi:10.1002/pol.1976.180140410Nicolson, P. C., & Vogt, J. (2001). Soft contact lens polymers: an evolution. Biomaterials, 22(24), 3273-3283. doi:10.1016/s0142-9612(01)00165-xCheng, X., & Pinsky, P. M. (2017). A numerical model for metabolism, metabolite transport and edema in the human cornea. Computer Methods in Applied Mechanics and Engineering, 314, 323-344. doi:10.1016/j.cma.2016.09.014Li, L., & Tighe, B. (2005). Numerical simulation of corneal transport processes. 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Comments to paper entitled "Predicting scleral GP lens entrapped tear layer oxygen tensions"

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Continuum electrostatic calculations of the pK

We have computed the pKa’s of the ionizable residues of a protein ion channel, the Staphylococcus aureus toxin $\alpha$ -hemolysin, by using two types of input structures, namely the crystal structure of the heptameric $\alpha$ -hemolysin and a set of over four hundred snapshots from a 4.38ns Molecular Dynamics simulation of the protein inserted in a phospholipid planar bilayer. The comparison of the dynamic picture provided by the Molecular Simulation with the static one based on the X-ray crystal structure of the protein embedded in a lipid membrane allows analyzing the influence of the fluctuations in the protein structure on its ionization properties. We find that the use of the dynamic structure provides interesting information about the sensitivity of the computed pKa of a given residue to small changes in the local structure. The calculated pKa are consistent with previous indirect estimations obtained from single-channel conductance and selectivity measurements

Selectivity of Protein Ion Channels and the Role of Buried Charges. Analytical Solutions, Numerical Calculations, and MD Simulations

The preference of large protein ion channels for cations or anions is mainly determined by the electrostatic interactions of mobile ions with charged residues of the protein. Here we discuss the widely spread paradigm that the charges determining the channel selectivity are only those that can be considered solvent-accessible because of their location near the permeation pathways of ions and water molecules. Theoretical predictions for the electric potential and average ion densities inside the pore are presented using several approaches of increasing resolution: from analytical and numerical solutions of electrostatic equations in a model channel up to all-atom molecular dynamics simulations and continuum electrostatic calculations performed in a particular biological channel, the bacterial porin OmpF. The results highlight the role of protein dieletric properties and the importance of the initial choice of the residue ionization states in the understanding of the molecular basis of large channel selectivity irrespective of the level of resolution of the computational approach used.We acknowledge support from the Spanish Ministry of Economy and Competitiveness (MINECO Project FIS2013- 40473-P), Generalitat Valenciana (Prometeo 2012/069), and Fundacio ́ Caixa Castello ́ -Bancaixa (Projects No. P1-1B2012-03 and P1-1B2012-16)

A refined model on flow and oxygen consumption in the human cornea depending on the oxygen tension at the interface cornea_post lens tear film during contact lens wear

[EN] The study of oxygen consumption rate under¿ in vivo¿ human cornea during contact lens wear has been technically a challenge and several attempts have been made in the last 20 years to model the physiology of the human cornea during contact lens wear. Unfortunately, some of these models, based on a constant corneal oxygen consumption rate, produce areas on the cornea where the oxygen tension is negative, which has no physical sense. In order to avoid such inconsistency, different researchers have developed alternative models of oxygen consumption, which predict the likely oxygen metrics available at the interface cornea/post lens tear film by determination of oxygen flux, oxygen consumption, and oxygen tension through the different layers (endothelium, stroma, and epithelium). Although oxygen deficiency produces corneal edema, corneal swelling, hypoxia, acidosis, and other abnormalities, the estimation of the oxygen distribution below the impact of a contact lens wear is interesting to know which lens transmissibility was adequate to maintain the cornea and avoid epithelial and stromal anoxia. The estimation of minimum transmissibility for a lens for extended wear applications will be very useful for both clinicians and manufacturers. The aim of this work is to present a complete discussion based on Monod kinetics model that permits give an estimation of oxygen partial pressure distribution, the profile distribution of corneal flux and oxygen consumption rate, and finally the estimation of the relaxation mechanism of the cornea depending on the oxygen tension at the interface cornea/post lens tear film. Relaxation time in this context can quantify the capability of the corneal tissue to adapt to increasing concentrations of oxygen. It is proposed this parameter as a biological meaningful indicator of the interaction between contact lens polymers and living tissues such as the corneal cellular layer.This work was supported by the Government of Spain (project no. PID2019-108434GB-100 AEI/FEDER,UE), and Universitat Jaume I (project no. UJI-B2018-53). This research was funded by DGTIC-UNAM, with access to the Miztli-UNAM supercomputer, with the project LANCADUNAM-DGTIC-055. This work was supported by UNAM-PAPIIT projects IG 100618, IG 114818, IN114318, IN120120.The authors want to thank Alberto López, Cain González, Alejandro Pompa, and Alan Ortega for technical help.Compañ Moreno, V.; Aguilella-Arzo, M.; Del Castillo, RM.; Espinos Gutierrez, FJ.; Del Castillo, LF. (2022). A refined model on flow and oxygen consumption in the human cornea depending on the oxygen tension at the interface cornea_post lens tear film during contact lens wear. Journal of Optometry. 15(2):160-174. https://doi.org/10.1016/j.optom.2020.12.002S16017415