Evaluation of different internal standardization approaches for the quantification of melatonin in cell culture samples by multiple heart-cutting two dimensional liquid chromatography tandem mass spectrometry.

We evaluate here different analytical strategies for the chromatographic separation and determination of N-acetyl-5-methoxytryptamine (MEL) and its oxidative metabolites N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), N1-acetyl-5-methoxykynuramine (AMK) and cyclic 3-hydroxymelatonin (c3OHM) in cell culture samples. Two dimensional liquid chromatography (2D-LC) in the multiple heart-cutting mode was compared with regular 1D chromatographic separations of MEL and its oxidative metabolites. Our results showed that the use of trifluoroacetic acid (TFA) as mobile phase modifier was required to obtain a satisfactory resolution and peak shapes particularly for c3OHM. As TFA is not compatible with ESI ionization the application of the MHC mode was mandatory for a proper chromatographic separation. We evaluate also different internal standardization approaches based on the combined use of a surrogate standard (5-methoxytryptophol) and an internal standard (6-methoxytryptamine) for MEL quantification in cell culture samples obtaining unsatisfactory results both by 1D- and 2D-LC-ESI-MS/MS (from 9 ± 2 to 186 ± 38%). We demonstrate that only the application of isotope dilution Mass Spectrometry through the use of an in house synthesized 13C isotopically labelled analogue provided quantitative MEL recoveries both by using 1D- and 2D-LC-ESI-MS/MS (99±1 and 98±1. Respectively) in androgen-insensitive human prostate carcinoma PC3 cells.

Determination of the Intracellular Complexation of Inorganic and Methylmercury in Cyanobacterium Synechocystis sp. PCC 6803.

Understanding of mercury (Hg) complexation with low molecular weight (LMW) bioligands will help elucidate its speciation. In natural waters, the rate of this complexation is governed by physicochemical, geochemical, and biochemical parameters. However, the role of bioligands involved in Hg intracellular handling by aquatic microorganisms is not well documented. Here, we combine the use of isotopically labeled Hg species (inorganic and monomethylmercury, iHg and MeHg) with gas or liquid chromatography coupling to elemental and molecular mass spectrometry to explore the role of intracellular biogenic ligands involved in iHg and MeHg speciation in cyanobacterium Synechocystis sp. PCC 6803, a representative phytoplankton species. This approach allowed to track resulting metabolic and newly found intracellular Hg biocomplexes (e.g., organic thiols) in Synechocystis sp. PCC 6803 finding different intracellular Hg species binding affinities with both high and low molecular weight (HMW and LMW) bioligands in the exponential and stationary phase. Furthermore, the parallel detection with both elemental and molecular ionization sources allowed the sensitive detection and molecular identification of glutathione (GSH) as the main low molecular weight binding ligand to iHg ((GS)2-Hg) and MeHg (GS-MeHg) in the cytosolic fraction. Such a novel experimental approach expands our knowledge on the role of biogenic ligands involved in iHg and MeHg intracellular handling in cyanobacteria.

Species-specific isotope tracking of mercury uptake and transformations by pico-nanoplankton in an eutrophic lake.

The present study aims to explore the bioaccumulation and biotic transformations of inorganic (iHg) and monomethyl mercury (MMHg) by natural pico-nanoplankton community from eutrophic lake Soppen, Switzerland. Pico-nanoplankton encompass mainly bacterioplankton, mycoplankton and phytoplankton groups with size between 0.2 and 20 µm. Species-specific enriched isotope mixture of 199iHg and 201MMHg was used to explore the accumulation, the subcellular distribution and transformations occurring in natural pico-nanoplankton sampled at 2 different depths (6.6 m and 8.3 m). Cyanobacteria, diatoms, cryptophyta, green algae and heterotrophic microorganisms were identified as the major groups of pico-nanoplankton with diatoms prevailing at deeper samples. Results showed that pico-nanoplankton accumulated both iHg and MMHg preferentially in the cell membrane/organelles, despite observed losses. The ratios between the iHg and MMHg concentrations measured in the membrane/organelles and cytosol were comparable for iHg and MMHg. Pico-nanoplankton demethylate added 201MMHg (~4 and 12% per day depending on cellular compartment), although the involved pathways are to further explore. Comparison of the concentrations of 201iHg formed from 201MMHg demethylation in whole system, medium and whole cells showed that 82% of the demethylation was biologically mediated by pico-nanoplankton. No significant methylation of iHg by pico-nanoplankton was observed. The accumulation of iHg and MMHg and the percentage of demethylated MMHg correlated positively with the relative abundance of diatoms and heterotrophic microorganisms in the pico-nanoplankton, the concentrations of TN, Mg2+, NO3-, NO2-, NH4+ and negatively with the concentrations of DOC, K+, Na+, Ca2+, SO42-. Taken together the results of the present field study confirm the role of pico-nanoplankton in Hg bioaccumulation and demethylation, however further research is needed to better understand the underlying mechanisms and interconnection between heterotrophic and autotrophic microorganisms.

Snow Albedo Seasonality and Trend from MODIS Sensor and Ground Data at Johnsons Glacier, Livingston Island, Maritime Antarctica.

The aim of this work is to investigate whether snow albedo seasonality and trend under all sky conditions at Johnsons Glacier (Livingston Island, Antarctica) can be tracked using the Moderate Resolution Imaging Spectroradiometer (MODIS) snow albedo daily product MOD10A1. The time span is from December 2006 to February 2015. As the MOD10A1 snow albedo product has never been used in Antarctica before, we also assess the performance for the MOD10A1 cloud mask. The motivation for this work is the need for a description of snow albedo under all sky conditions (including overcast days) using satellite data with mid-spatial resolution. In-situ albedo was filtered with a 5-day windowed moving average, while the MOD10A1 data were filtered using a maximum filter. Both in-situ and MOD10A1 data follow an exponential decay during the melting season, with a maximum decay of 0.049/0.094 day-1 (in-situ/MOD10A1) for the 2006-2007 season and a minimum of 0.016/0.016 day-1 for the 2009-2010 season. The duration of the decay varies from 85 days (2007-2008) to 167 days (2013-2014). Regarding the albedo trend, both data sets exhibit a slight increase of albedo, which may be explained by an increase of snowfall along with a decrease of snowmelt in the study area. Annual albedo increases of 0.2% and 0.7% are obtained for in-situ and MOD10A1 data, respectively, which amount to respective increases of 2% and 6% in the period 2006-2015. We conclude that MOD10A1 can be used to characterize snow albedo seasonality and trend on Livingston Island when filtered with a maximum filter.

Propuesta para el ajuste de las tablas estandarizadas del índice de masa corporal para las personas adultas mayores en México / Proposal for the adjustment of the standardized tables of body mass index for older people in Mexico

Objetivo. Describir la distribución normalizada de los valores del índice de masa corporal (IMC) en la población adulta mayor mexicana. Material y método. Se utilizó la fórmula original de Quetelet para determinar el IMC de los participantes en SABE. Este es un estudio de campo, descriptivo, transversal, simultaneo, de corte comparativo. Fue llevado a cabo en 12 entidades federativas mexicanas en personas adultas mayores de 60 y más años de edad, residentes habituales de su domicilio actual al momento de realizarse la encuesta. La muestra abarcó a 12 411 individuos con representatividad estadística. El estudio se basó en estadística descriptiva. En el manejo estadístico de la información se utilizó como prueba no parametrica la χ² con un grado de libertad, y un intervalo de confianza > 95%. Se consideraron como valores estadísticamente significativos aquellos con p≤0,005. Resultados. Se encontró que los conceptos de IMC "normal", "sobrepeso" y "obesidad I" en SABE fueron mayores que los aportados por las actuales tablas estandarizadas de la OMS, lo que coincide en lo relativo a la obesidad grados II y III.

Objective. To describe the standard distribution of the values of the of body mass index in the Mexican older population. Material and methods. BMI was determined by the original Quetelet's formula in the participants of SABE study. This is a descriptive, cross-sectional, simultaneous and comparative field study. It was carried out a survey in 12 Mexican States in 60 year-old and elder usual adult residents. The representative sample comprised 12 411 individuals. The study was based on descriptive statistics. For analysis, it was used the non-parametric χ² test with one degree of freedom and an interval confidence<95%. It was considered as statistically significant those values with p≤0,005. Results. We found that the concepts of "normal" BMI, "overweight" and "obesity I" in SABE study were greater than the provided by the current standardized tables, and there coincidence with obesity grades II and III.

Investigación clinicoepidemiológica en envejecimiento: metodología del proyecto encuesta salud, bienestar y envejecimiento (SABE) en México / Epidemiological clinical research in aging: methodology of the project survey health, wellbeing and ageing in Mexico

La población de personas adultas mayores crece de forma paulatina y sostenida en el mundo y por ende en nuestro país. Sin embargo, la información que se tiene sobre la forma de vida, salud y bienestar de este grupo poblacional es limitada debido a que la mayor parte de las investigaciones en adultos mayores es derivada del estudio de grupos pequeños con patología bien circunscrita y características especiales. Por otro lado, la realización de estudios, en la población abierta, que permitan establecer la demografía y epidemiología de las personas mayores de 60 años requieren de una gran infraestructura y recursos tanto humanos como económicos. El Proyecto-Encuesta Salud Bienestar y Envejecimiento (SABE), mediante la realización de un estudio tipo encuesta, tiene la finalidad de obtener dicha información contando con la participación del Sector Salud, instituciones de educación superior así como organizaciones no gubernamentales lo que constituye un logro interinstitucional. Para la realización del proyecto SABE se ha seguido con rigurosidad científica el protocolo y para su puesta en marcha hubo la necesidad de la integración intersectorial de las instituciones que brindan atención a los adultos mayores mexicanos, ya sea dentro del contexto de la seguridad o asistencia social. Los alcances de SABE permitirán la creación y difusión del conocimiento derivado del mismo. En este documento, se expone y analiza de forma breve y concreta la metodología operativa de SABE México, lo que significa dar el primer paso para que otros investigadores interesados en el tema, realicen este tipo de estudios. Dada la experiencia que se ha ido generando en la realización de SABE México, este tipo de documentos sirven como base para proponer e iniciar las acciones al respecto.

The elderly population grows so gradual and sustained in the world and therefore in our country. However, information that is on the way of life, health and well-being of this population group is limited since most of the research in older adults is derived from the study of small groups with well circumscribed pathology and special features. On the other hand, open population studies to establish the demography and epidemiology of people older than 60 years require a large infrastructure and resources both human and financial. Project- Survey Health, Wellbeing and Ageing (SABE, in Spanish)), through a study type survey, has the purpose of obtaining such information with the participation of the Health Sector, institutions of higher education as well as organizations NGO constituting an interinstitutional achievement. For the implementation of the project SABE the Protocol has been followed with scientific rigor and for it simplementation underway there was the need to cross-sectoral integration of institutions providing care to Mexican older adults, either within the context of the social security or welfare. The reaches of SABE will enable the creation and dissemination of the knowledge derived from it. In this document, it exposes and analyzes operational methodology of a brief and concrete way of SABE Mexico, which means the first step so that other researchers interested in the topic, take place this type of study. Given the experience that has been generated in the implementation of SABE Mexico, this type of documents serves as the basis to propose and initiate actions in this regard.

Spanish experience in liver transplantation for hilar and peripheral cholangiocarcinoma.

OBJECTIVE: To assess the real utility of orthotopic liver transplantation (OLT) in patients with cholangiocarcinoma, we need series with large numbers of cases and long follow-ups. The aim of this paper is to review the Spanish experience in OLT for hilar and peripheral cholangiocarcinoma and to try to identify the prognostic factors that could influence survival. SUMMARY BACKGROUND DATA: Palliative treatment of nondisseminated irresectable cholangiocarcinoma carries a zero 5-year survival rate. The role of OLT in these patients is controversial, due to the fact that the survival rate is lower than with other indications for transplantation and due to the lack of organs. METHODS: We retrospectively reviewed 59 patients undergoing OLT in Spain for cholangiocarcinoma (36 hilar and 23 peripheral) over a period of 13 years. We present the results and prognostic factors that influence survival. RESULTS: The actuarial survival rate for hilar cholangiocarcinoma at 1, 3, and 5 years was 82%, 53%, and 30%, and for peripheral cholangiocarcinoma 77%, 65%, and 42%. The main cause of death, with both types of cholangiocarcinoma, was tumor recurrence (present in 53% and 35% of patients, respectively). Poor prognosis factors were vascular invasion (P < 0.01) and IUAC classification stages III-IVA (P < 0.01) for hilar cholangiocarcinoma and perineural invasion (P < 0.05) and stages III-IVA (P < 0.05) for peripheral cholangiocarcinoma. CONCLUSIONS: OLT for nondisseminated irresectable cholangiocarcinoma has higher survival rates at 3 and 5 years than palliative treatments, especially with tumors in their initial stages, which means that more information is needed to help better select cholangiocarcinoma patients for transplantation.

Presence of methylated arginine derivatives in orthotopic human liver transplantation: relevance for liver function.

Orthotopic liver transplantation (OLT) is a frequent option in the treatment of liver diseases. During the cold ischemia period of the donor liver, there is an accumulation of metabolites that are potent inhibitors of the cytokine-inducible and endothelial nitric oxide synthase isoenzymes. We identified the presence of L-N-monomethylarginine and asymmetric dimethylarginine (ADMA) as the main inhibitors by means of analytic high-pressure liquid chromatography and mass spectrometry techniques. An average ADMA concentration of 450 micromol/L was measured in the preservation medium of donor livers with poor outcomes after OLT. A statistically significant relationship was observed between the concentration of methylated arginine derivatives in the graft and liver function after OLT. These data suggest that measurement of methylated arginine, released after liver protein catabolism, might provide an indication of functional status of the liver that can help the development of strategies intended to improve graft viability.